diff --git a/documentation/content/en/articles/building-products/_index.adoc b/documentation/content/en/articles/building-products/_index.adoc
index cf50b55302..c88a93e0fb 100644
--- a/documentation/content/en/articles/building-products/_index.adoc
+++ b/documentation/content/en/articles/building-products/_index.adoc
@@ -1,382 +1,382 @@
 ---
 title: Building Products with FreeBSD
 authors:
   - author: Joseph Koshy
     email: jkoshy@FreeBSD.org
 organizations:
   - organization: The FreeBSD Project
 description: How FreeBSD can help you build a better product
 trademarks: ["freebsd", "general"]
 tags: ["FreeBSD", "FreeBSD as base for your product"]
 ---
 
 = Building Products with FreeBSD
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 
 ifeval::["{backend}" == "html5"]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/urls.adoc[]
 :imagesdir: ../../../images/articles/building-products/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 include::../../../../shared/releases.adoc[]
 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 :imagesdir: ../../../../static/images/articles/building-products/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 include::../../../../shared/releases.adoc[]
 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 :imagesdir: ../../../../static/images/articles/building-products/
 endif::[]
 
 [.abstract-title]
 Abstract
 
 The FreeBSD project is a worldwide, volunteer based, and collaborative project, which develops a portable and high-quality operating system.
 The FreeBSD project distributes the source code for its product under a liberal license, with the intention of encouraging the use of its code.
 Collaborating with the FreeBSD project can help organizations reduce their time to market, reduce engineering costs and improve their product quality.
 
 This article examines the issues in using FreeBSD code in appliances and software products.
 It highlights the characteristics of FreeBSD that make it an excellent substrate for product development.
 The article concludes by suggesting a few "best practices" for organizations collaborating with the FreeBSD project.
 
 '''
 
 toc::[]
 
 [[introduction]]
 == Introduction
 
 FreeBSD today is well-known as a high-performance server operating system.
 It is deployed on millions of web servers and internet-facing hosts worldwide.
 FreeBSD code also forms an integral part of many products, ranging from appliances such as network routers, firewalls, and storage devices, to personal computers.
 Portions of FreeBSD have also been used in commercial shrink-wrapped software (see <<freebsd-intro>>).
 
 In this article we look at the link:https://www.FreeBSD.org/[FreeBSD project] as a software engineering resource-as a collection of building blocks and processes which you can use to build products.
 
 While FreeBSD's source is distributed freely to the public, to fully enjoy the benefits of the project's work, organizations need to _collaborate_ with the project.
 In subsequent sections of this article we discuss effective means of collaboration with the project and the pitfalls that need to be avoided while doing so.
 
 *Caveat Reader.* The author believes that the characteristics of the FreeBSD Project listed in this article were substantially true at the time the article was conceived and written (2005).
 However, the reader should keep in mind that the practices and processes used by open-source communities can change over time, and that the information in this article should therefore be taken as indicative rather than normative.
 
 === Target Audience
 
 This document would be of interest to the following broad groups of people:
 
 * Decision makers in product companies looking at ways to improve their product quality, reduce their time to market and lower engineering costs in the long term.
 * Technology consultants looking for best-practices in leveraging "open-source".
 * Industry observers interested in understanding the dynamics of open-source projects.
 * Software developers seeking to use FreeBSD and looking for ways to contribute back.
 
 === Article Goals
 
 After reading this article you should have:
 
 * An understanding of the goals of the FreeBSD Project and its organizational structure.
 * An understanding of its development model and release engineering processes.
 * An understanding of how conventional corporate software development processes differ from that used in the FreeBSD project.
 * Awareness of the communication channels used by the project and the level of transparency you can expect.
 * Awareness of optimal ways of working with the project-how best to reduce engineering costs, improve time to market, manage security vulnerabilities, and preserve future compatibility with your product as the FreeBSD project evolves.
 
 === Article Structure
 
 The rest of the article is structured as follows:
 
 * <<freebsd-intro>> introduces the FreeBSD project, explores its organizational structure, key technologies and release engineering processes.
 * <<freebsd-collaboration>> describes ways to collaborate with the FreeBSD project. It examines common pitfalls encountered by corporates working with voluntary projects like FreeBSD.
 * <<conclusion>> concludes.
 
 [[freebsd-intro]]
 == FreeBSD as a set of building blocks
 
 FreeBSD makes an excellent foundation on which to build products:
 
 * FreeBSD source code is distributed under a liberal BSD license facilitating its adoption in commercial products <<Mon2005>> with minimum hassle.
 * The FreeBSD project has excellent engineering practices that can be leveraged.
 * The project offers exceptional transparency into its workings, allowing organizations using its code to plan effectively for the future.
 * The culture of the FreeBSD project, carried over from the Computer Science Research Group at The University of California, Berkeley <<McKu1999-1>>, fosters high-quality work. Some features in FreeBSD define the state of the art.
 
 <<GoldGab2005>> examines the business reasons for using open-source in greater detail.
 For organizations, the benefits of using FreeBSD components in their products include a shorter time to market, lower development costs and lower development risks. 
 
 === Building with FreeBSD
 
 Here are a few ways organizations have used FreeBSD:
 
 * As an upstream source for tested code for libraries and utilities.
-+ 
++
 By being "downstream" of the project, organizations leverage the new features, bug fixes and testing that the upstream code receives.
 * As an embedded OS (for example, for an OEM router and firewall device). In this model, organizations use a customized FreeBSD kernel and application program set along with a proprietary management layer for their device. OEMs benefit from new hardware support being added by the FreeBSD project upstream, and from the testing that the base system receives.
-+ 
++
 FreeBSD ships with a self-hosting development environment that allows easy creation of such configurations.
 * As a Unix compatible environment for the management functions of high-end storage and networking devices, running on a separate processor "blade".
-+ 
++
 FreeBSD provides the tools for creating dedicated OS and application program images.
 Its implementation of a BSD unix API is mature and tested.
 FreeBSD can also provide a stable cross-development environment for the other components of the high-end device.
 * As a vehicle to get widespread testing and support from a worldwide team of developers for non-critical "intellectual property".
-+ 
++
 In this model, organizations contribute useful infrastructural frameworks to the FreeBSD project (for example, see man:netgraph[3]).
 The widespread exposure that the code gets helps to quickly identify performance issues and bugs.
 The involvement of top-notch developers also leads to useful extensions to the infrastructure that the contributing organization also benefits from.
 * As a development environment supporting cross-development for embedded OSes like http://www.rtems.com/[RTEMS] and http://ecos.sourceware.org/[eCOS].
-+ 
++
 There are many full-fledged development environments in the {numports}-strong collection of applications ported and packaged with FreeBSD.
 * As a way to support a Unix-like API in an otherwise proprietary OS, increasing its palatability for application developers.
-+ 
++
 Here parts of FreeBSD's kernel and application programs are "ported" to run alongside other tasks in the proprietary OS.
 The availability of a stable and well tested Unix(TM) API implementation can reduce the effort needed to port popular applications to the proprietary OS.
 As FreeBSD ships with high-quality documentation for its internals and has effective vulnerability management and release engineering processes, the costs of keeping up-to-date are kept low.
 
 [[freebsd-technologies]]
 === Technologies
 
 There are a large number of technologies supported by the FreeBSD project.
 A selection of these are listed below:
 
 * A complete system that can cross-host itself for link:https://www.FreeBSD.org/platforms/[many architectures:]
 * A modular symmetric multiprocessing capable kernel, with loadable kernel modules and a flexible and easy to use configuration system.
 * Support for emulation of Linux(TM) and SVR4 binaries at near machine speeds. Support for binary Windows(TM) (NDIS) network drivers.
 * Libraries for many programming tasks: archivers, FTP and HTTP support, thread support, in addition to a full POSIX(TM) like programming environment.
 * Security features: Mandatory Access Control (man:mac[9]), jails (man:jail[2]), ACLs, and in-kernel cryptographic device support.
 * Networking features: firewall-ing, QoS management, high-performance TCP/IP networking with support for many extensions.
-+ 
++
 FreeBSD's in-kernel Netgraph (man:netgraph[4]) framework allows kernel networking modules to be connected together in flexible ways.
 * Support for storage technologies: Fibre Channel, SCSI, software and hardware RAID, ATA and SATA.
-+ 
++
 FreeBSD supports a number of filesystems, and its native UFS2 filesystem supports soft updates, snapshots and very large filesystem sizes (16TB per filesystem) <<McKu1999>>.
-+ 
++
 FreeBSD's in-kernel GEOM (man:geom[4]) framework allows kernel storage modules to be composed in flexible ways.
 * Over {numports} ported applications, both commercial and open-source, managed via the FreeBSD ports collection.
 
 === Organizational Structure
 
 FreeBSD's organizational structure is non-hierarchical.
 
 There are essentially two kinds of contributors to FreeBSD, general users of FreeBSD, and developers with write access (known as _committers_ in the jargon) to the source base.
 
 There are many thousands of contributors in the first group; the vast majority of contributions to FreeBSD come from individuals in this group.
 Commit rights (write access) to the repository are granted to individuals who contribute consistently to the project.
 Commit rights come with additional responsibilities, and new committers are assigned mentors to help them learn the ropes.
 
 .FreeBSD Organization
 image::freebsd-organization.png[]
 
 Conflict resolution is performed by a nine member "Core Team" that is elected from the group of committers.
 
 FreeBSD does not have "corporate" committers.
 Individual committers are required to take responsibility for the changes they introduce to the code.
 The link:{committers-guide}[FreeBSD Committer's guide] <<ComGuide>> documents the rules and responsibilities for committers.
 
 FreeBSD's project model is examined in detail in <<Nik2005>>.
 
 === FreeBSD Release Engineering Processes
 
 FreeBSD's release engineering processes play a major role in ensuring that its released versions are of a high quality.
 At any point of time, FreeBSD's volunteers support multiple code lines (<<fig-freebsd-branches, FreeBSD Release Branches>>):
 
 * New features and disruptive code enters on the development branch, also known as the _-CURRENT_ branch.
 * _-STABLE_ branches are code lines that are branched from HEAD at regular intervals. Only tested code is allowed onto a -STABLE branch. New features are allowed once they have been tested and stabilized in the -CURRENT branch.
 * _-RELEASE_ branches are maintained by the FreeBSD security team. Only bug fixes for critical issues are permitted onto -RELEASE branches.
 
 [[fig-freebsd-branches]]
 .FreeBSD Release Branches
 image::freebsd-branches.png[]
 
 Code lines are kept alive for as long as there is user and developer interest in them.
 
 Machine architectures are grouped into "tiers"; _Tier 1_ architectures are fully supported by the project's release engineering and security teams, _Tier 2_ architectures are supported on a best effort basis, and experimental architectures comprise _Tier 3_.
 The list of link:{committers-guide}#archs[supported architectures] is part of the FreeBSD documentation collection.
 
 The release engineering team publishes a link:https://www.FreeBSD.org/releng/[road map] for future releases of FreeBSD on the project's web site.
 The dates laid down in the road map are not deadlines; FreeBSD is released when its code and documentation are ready.
 
 FreeBSD's release engineering processes are described in <<RelEngDoc>>.
 
 [[freebsd-collaboration]]
 == Collaborating with FreeBSD
 
 Open-source projects like FreeBSD offer finished code of a very high quality.
 
 While access to quality source code can reduce the cost of initial development, in the long-term the costs of managing change begin to dominate.
 As computing environments change over the years and new security vulnerabilities are discovered, your product too needs to change and adapt.
 Using open-source code is best viewed not as a one-off activity, but as an __ongoing process__.
 The best projects to collaborate with are the ones that are __live__; i.e., with an active community, clear goals and a transparent working style.
 
 * FreeBSD has an active developer community around it. At the time of writing there are many thousands of contributors from every populated continent in the world and over 300 individuals with write access to the project's source repositories.
 * The goals of the FreeBSD project are <<Hub1994>>:
 
 ** To develop a high-quality operating system for popular computer hardware, and,
 ** To make our work available to all under a liberal license.
 
 * FreeBSD enjoys an open and transparent working culture. Nearly all discussion in the project happens by email, on https://lists.freebsd.org/mailman/listinfo[public mailing lists] that are also archived for posterity. The project's policies are link:https://www.FreeBSD.org/internal/policies/[documented] and maintained under revision control. Participation in the project is open to all.
 
 [[freebsd-org]]
 === Understanding FreeBSD culture
 
 To be able to work effectively with the FreeBSD project, you need to understand the project's culture.
 
 Volunteer driven projects operate under different rules than for-profit corporates.
 A common mistake that companies make when venturing into the open-source world is that of underplaying these differences.
 
 *Motivation.* Most contributions to FreeBSD are done voluntarily without monetary rewards entering the picture. The factors that motivate individuals are complex, ranging from altruism, to an interest in solving the kinds of problems that FreeBSD attempts to solve. In this environment, "elegance is never optional"<<Nor1993>>.
 
 *The Long Term View.* FreeBSD traces its roots back nearly twenty years to the work of the Computer Science Research Group at the University of California Berkeley.footnote:[FreeBSD's source repository contains a history of the project since its inception, and there are CDROMs available that contain earlier code from the CSRG.] A number of the original CSRG developers remain associated with the project.
 
 The project values long-term perspectives <<Nor2001>>. A frequent acronym encountered in the project is DTRT, which stands for "Do The Right Thing".
 
 *Development Processes.* Computer programs are tools for communication: at one level programmers communicate their intentions using a precise notation to a tool (a compiler) that translates their instructions to executable code.
 At another level, the same notation is used for communication of intent between two programmers.
 
 Formal specifications and design documents are seldom used in the project.
 Clear and well-written code and well-written change logs (<<fig-change-log, A sample change log entry>>) are used in their place.
 FreeBSD development happens by "rough consensus and running code"<<Carp1996>>.
 
 [.programlisting]
 ....
 r151864 | bde | 2005-10-29 09:34:50 -0700 (Sat, 29 Oct 2005) | 13 lines
 Changed paths:
    M /head/lib/msun/src/e_rem_pio2f.c
 
 Use double precision to simplify and optimize arg reduction for small
 and medium size args too: instead of conditionally subtracting a float
 17+24, 17+17+24 or 17+17+17+24 bit approximation to pi/2, always
 subtract a double 33+53 bit one.  The float version is now closer to
 the double version than to old versions of itself -- it uses the same
 33+53 bit approximation as the simplest cases in the double version,
 and where the float version had to switch to the slow general case at
 |x| == 2^7*pi/2, it now switches at |x| == 2^19*pi/2 the same as the
 double version.
 
 This speeds up arg reduction by a factor of 2 for |x| between 3*pi/4 and
 2^7*pi/4, and by a factor of 7 for |x| between 2^7*pi/4 and 2^19*pi/4.
 ....
 .A sample change log entry [[fig-change-log]]
 
 Communication between programmers is enhanced by the use of a common coding standard man:style[9].
 
 *Communication Channels.* FreeBSD's contributors are spread across the world.
 Email (and to a lesser extent, IRC) is the preferred means of communication in the project.
 
 === Best Practices for collaborating with the FreeBSD project
 
 We now look at a few best practices for making the best use of FreeBSD in product development.
 
 Plan for the long term::
 Setup processes that help in tracking the development of FreeBSD.
 For example:
 +
 *Track FreeBSD source code.* The project makes it easy to mirror its SVN repository using link:{committers-guide}#svn-advanced-use-setting-up-svnsync[svnsync]. Having the complete history of the source is useful when debugging complex problems and offers valuable insight into the intentions of the original developers. Use a capable source control system that allows you to easily merge changes between the upstream FreeBSD code base and your own in-house code.
 +
 <<fig-svn-blame, An annotated source listing generated using `svn blame`>> shows a portion of an annotated listing of the file referenced by the change log in <<fig-change-log, A sample change log entry>>.
 The ancestry of each line of the source is clearly visible.
 Annotated listings showing the history of every file that is part of FreeBSD are https://svnweb.freebsd.org/[available on the web].
 +
 [.programlisting]
 ....
 #REV         #WHO #DATE                                        #TEXT
 
 176410        bde 2008-02-19 07:42:46 -0800 (Tue, 19 Feb 2008) #include <sys/cdefs.h>
 176410        bde 2008-02-19 07:42:46 -0800 (Tue, 19 Feb 2008) __FBSDID("$FreeBSD$");
   2116        jkh 1994-08-19 02:40:01 -0700 (Fri, 19 Aug 1994) 
   2116        jkh 1994-08-19 02:40:01 -0700 (Fri, 19 Aug 1994) /* __ieee754_rem_pio2f(x,y)
   8870    rgrimes 1995-05-29 22:51:47 -0700 (Mon, 29 May 1995)  *
 176552        bde 2008-02-25 05:33:20 -0800 (Mon, 25 Feb 2008)  * return the remainder of x rem pi/2 in *y
 176552        bde 2008-02-25 05:33:20 -0800 (Mon, 25 Feb 2008)  * use double precision for everything except passing x
 152535        bde 2005-11-16 18:20:04 -0800 (Wed, 16 Nov 2005)  * use __kernel_rem_pio2() for large x
   2116        jkh 1994-08-19 02:40:01 -0700 (Fri, 19 Aug 1994)  */
   2116        jkh 1994-08-19 02:40:01 -0700 (Fri, 19 Aug 1994) 
 176465        bde 2008-02-22 07:55:14 -0800 (Fri, 22 Feb 2008) #include <float.h>
 176465        bde 2008-02-22 07:55:14 -0800 (Fri, 22 Feb 2008) 
   2116        jkh 1994-08-19 02:40:01 -0700 (Fri, 19 Aug 1994) #include "math.h"
 ....
 .An annotated source listing generated using `svn blame` [[fig-svn-blame]]
 +
 *Use a gatekeeper.* Appoint a _gatekeeper_ to monitor FreeBSD development, to keep an eye out for changes that could potentially impact your products.
 +
 *Report bugs upstream.* If you notice bug in the FreeBSD code that you are using, file a https://www.FreeBSD.org/support/bugreports/[bug report].
 This step helps ensure that you do not have to fix the bug the next time you take a code drop from upstream.
 Leverage FreeBSD's release engineering efforts::
 Use code from a -STABLE development branch of FreeBSD.
 These development branches are formally supported by FreeBSD's release engineering and security teams and comprise of tested code. 
 
 Donate code to reduce costs::
 A major proportion of the costs associated with developing products is that of doing maintenance.
 By donating non-critical code to the project, you benefit by having your code see much wider exposure than it would otherwise get.
 This in turn leads to more bugs and security vulnerabilities being flushed out and performance anomalies being identified and fixed. 
 
 Get support effectively::
 For products with tight deadlines, it is recommended that you hire or enter into a consulting agreement with a developer or firm with FreeBSD experience. 
 The {freebsd-jobs} is a useful communication channel to find talent.
 The FreeBSD project maintains a link:https://www.FreeBSD.org/commercial/consult_bycat/[gallery of consultants and consulting firms] undertaking FreeBSD work.
 The http://www.bsdcertification.org/[BSD Certification Group] offers certification for all the major BSD derived OSes.
 +
 For less critical needs, you can ask for help on the http://lists.FreeBSD.org/mailman/listinfo[project mailing lists].
 A useful guide to follow when asking for help is given in <<Ray2004>>. 
 Publicize your involvement::
 You are not required to publicize your use of FreeBSD, but doing so helps both your effort as well as that of the project.
 +
 Letting the FreeBSD community know that your company uses FreeBSD helps improve your chances of attracting high quality talent.
 A large roster of support for FreeBSD also means more mind share for it among developers.
 This in turn yields a healthier foundation for your future.
 Support FreeBSD developers::
 Sometimes the most direct way to get a desired feature into FreeBSD is to support a developer who is already looking at a related problem.
 Help can range from hardware donations to direct financial assistance.
 In some countries, donations to the FreeBSD project enjoy tax benefits.
 The project has a dedicated link:https://www.FreeBSD.org/donations/[donations liaison] to assist donors.
 The project also maintains a web page where developers link:https://www.FreeBSD.org/donations/wantlist/[list their needs]. 
 +
 As a policy the FreeBSD project link:{contributors}[acknowledges] all contributions received on its web site.
 
 [[conclusion]]
 == Conclusion
 
 The FreeBSD project's goals are to create and give away the source code for a high-quality operating system.
 By working with the FreeBSD project you can reduce development costs and improve your time to market in a number of product development scenarios.
 
 We examined the characteristics of the FreeBSD project that make it an excellent choice for being part of an organization's product strategy.
 We then looked at the prevailing culture of the project and examined effective ways of interacting with its developers.
 The article concluded with a list of best-practices that could help organizations collaborating with the project.
 
 :sectnums!:
 
 [bibliography]
 == Bibliography
 
 [[Carp1996]] [Carp1996] http://www.ietf.org/rfc/rfc1958.txt[The Architectural Principles of the Internet] B. Carpenter. The Internet Architecture Board.The Internet Architecture Board. Copyright(R) 1996.
 
 [[ComGuide]] [ComGuide] link:{committers-guide}[Committer's Guide] The FreeBSD Project. Copyright(R) 2005.
 
 [[GoldGab2005]] [GoldGab2005] http://dreamsongs.com/IHE/IHE.html[Innovation Happens Elsewhere: Open Source as Business Strategy] Ron Goldman. Richard Gabriel. Copyright(R) 2005. Morgan-Kaufmann.
 
 [[Hub1994]] [Hub1994] link:{contributing}[Contributing to the FreeBSD Project] Jordan Hubbard. Copyright(R) 1994-2005. The FreeBSD Project.
 
 [[McKu1999]] [McKu1999] http://www.usenix.org/publications/library/proceedings/usenix99/mckusick.html[Soft Updates: A Technique for Eliminating Most Synchronous Writes in the Fast Filesystem] Kirk McKusick. Gregory Ganger. Copyright(R) 1999.
 
 [[McKu1999-1]] [McKu1999-1] http://www.oreilly.com/catalog/opensources/book/kirkmck.html[Twenty Years of Berkeley Unix: From AT&T-Owned to Freely Redistributable] Marshall Kirk McKusick. http://www.oreilly.com/catalog/opensources/book/toc.html[Open Sources: Voices from the Open Source Revolution] O'Reilly Inc.. Copyright(R) 1993.
 
 [[Mon2005]] [Mon2005] link:{bsdl-gpl}[Why you should use a BSD style license for your Open Source Project] Bruce Montague. The FreeBSD Project. Copyright(R) 2005.
 
 [[Nik2005]] [Nik2005] link:{dev-model}[A project model for the FreeBSD Project] Niklas Saers. Copyright(R) 2005. The FreeBSD Project.
 
 [[Nor1993]] [Nor1993] http://www.norvig.com/luv-slides.ps[Tutorial on Good Lisp Programming Style] Peter Norvig. Kent Pitman. Copyright(R) 1993.
 
 [[Nor2001]] [Nor2001] http://www.norvig.com/21-days.html[Teach Yourself Programming in Ten Years] Peter Norvig. Copyright(R) 2001.
 
 [[Ray2004]] [Ray2004] http://www.catb.org/~esr/faqs/smart-questions.html[How to ask questions the smart way] Eric Steven Raymond. Copyright(R) 2004.
 
 [[RelEngDoc]] [RelEngDoc] link:{releng}[FreeBSD Release Engineering] Murray Stokely. Copyright(R) 2001. The FreeBSD Project.
diff --git a/documentation/content/en/articles/committers-guide/_index.adoc b/documentation/content/en/articles/committers-guide/_index.adoc
index 1767095908..4d434552fd 100644
--- a/documentation/content/en/articles/committers-guide/_index.adoc
+++ b/documentation/content/en/articles/committers-guide/_index.adoc
@@ -1,3853 +1,3853 @@
 ---
 title: Committer's Guide
 authors:
   - author: The FreeBSD Documentation Project
 copyright: 1999-2021 The FreeBSD Documentation Project
 description: Introductory information for FreeBSD committers
 trademarks: ["freebsd", "coverity", "ibm", "intel", "general"]
 weight: 25
 tags: ["FreeBSD Committer's Guide", "Guide", "Community"]
 ---
 
 = Committer's Guide
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 ifeval::["{backend}" == "html5"]
 include::shared/authors.adoc[]
 include::shared/en/teams.adoc[lines=16..-1]
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 endif::[]
 
 ifeval::["{backend}" == "pdf"]
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 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 include::../../../../shared/authors.adoc[]
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 endif::[]
 
 [.abstract-title]
 Abstract
 
 This document provides information for the FreeBSD committer community.
 All new committers should read this document before they start, and existing committers are strongly encouraged to review it from time to time.
 
 Almost all FreeBSD developers have commit rights to one or more repositories.
 However, a few developers do not, and some of the information here applies to them as well.
 (For instance, some people only have rights to work with the Problem Report database).
 Please see <<non-committers>> for more information.
 
 This document may also be of interest to members of the FreeBSD community who want to learn more about how the project works.
 
 '''
 
 toc::[]
 
 [[admin]]
 == Administrative Details
 
 [.informaltable]
 [cols="1,1", frame="none"]
 |===
 
 |_Login Methods_
 |man:ssh[1], protocol 2 only
 
 |_Main Shell Host_
 |`freefall.FreeBSD.org`
 
 |_Reference Machines_
 |`ref*.FreeBSD.org`, `universe*.freeBSD.org` (see also link:https://www.FreeBSD.org/internal/machines/[FreeBSD Project Hosts])
 
 |_SMTP Host_
 |`smtp.FreeBSD.org:587` (see also <<smtp-setup>>).
 
 |`_src/_` Git Repository
 |`ssh://git@gitrepo.FreeBSD.org/src.git` (see also <<git-getting-started-base-layout>>).
 
 |`_doc/_` Git Repository
 |`ssh://git@gitrepo.FreeBSD.org/doc.git` (see also <<git-getting-started-doc-layout>>).
 
 |`_ports/_` Git Repository
 |`ssh://git@gitrepo.FreeBSD.org/ports.git` (see also <<git-getting-started-ports-layout>>).
 
 |_Internal Mailing Lists_
 |developers (technically called all-developers), doc-developers, doc-committers, ports-developers, ports-committers, src-developers, src-committers. (Each project repository has its own -developers and -committers mailing lists. Archives for these lists can be found in the files [.filename]#/local/mail/repository-name-developers-archive# and [.filename]#/local/mail/repository-name-committers-archive# on the `FreeBSD.org` cluster.)
 
 |_Core Team monthly reports_
 |[.filename]#/home/core/public/monthly-reports# on the `FreeBSD.org` cluster.
 
 |_Ports Management Team monthly reports_
 |[.filename]#/home/portmgr/public/monthly-reports# on the `FreeBSD.org` cluster.
 
 |_Noteworthy `src/` Git Branches:_
 |`stable/n` (`n`-STABLE), `main` (-CURRENT)
 |===
 
 man:ssh[1] is required to connect to the project hosts. For more information, see <<ssh.guide>>.
 
 Useful links:
 
 * link:https://www.FreeBSD.org/internal/[FreeBSD Project Internal Pages]
 * link:https://www.FreeBSD.org/internal/machines/[FreeBSD Project Hosts]
 * link:https://www.FreeBSD.org/administration/[FreeBSD Project Administrative Groups]
 
 [[pgpkeys]]
 == OpenPGP Keys for FreeBSD
 
 Cryptographic keys conforming to the OpenPGP (__Pretty Good Privacy__) standard are used by the FreeBSD project to authenticate committers.
 Messages carrying important information like public SSH keys can be signed with the OpenPGP key to prove that they are really from the committer.
 See http://www.nostarch.com/pgp_ml.htm[PGP & GPG: Email for the Practical Paranoid by Michael Lucas] and http://en.wikipedia.org/wiki/Pretty_Good_Privacy[] for more information.
 
 [[pgpkeys-creating]]
 === Creating a Key
 
 Existing keys can be used, but should be checked with [.filename]#documentation/tools/checkkey.sh# first.
 In this case, make sure the key has a FreeBSD user ID.
 
 For those who do not yet have an OpenPGP key, or need a new key to meet FreeBSD security requirements, here we show how to generate one.
 
 [[pgpkeys-create-steps]]
 [.procedure]
 ====
 . Install [.filename]#security/gnupg#. Enter these lines in [.filename]#~/.gnupg/gpg.conf# to set minimum acceptable defaults:
 +
 [.programlisting]
 ....
 fixed-list-mode
 keyid-format 0xlong
 personal-digest-preferences SHA512 SHA384 SHA256 SHA224
 default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 BZIP2 ZLIB ZIP Uncompressed
 use-agent
 verify-options show-uid-validity
 list-options show-uid-validity
 sig-notation issuer-fpr@notations.openpgp.fifthhorseman.net=%g
 cert-digest-algo SHA512
 ....
 . Generate a key:
 +
 [source,shell]
 ....
 % gpg --full-gen-key
 gpg (GnuPG) 2.1.8; Copyright (C) 2015 Free Software Foundation, Inc.
 This is free software: you are free to change and redistribute it.
 There is NO WARRANTY, to the extent permitted by law.
 
 Warning: using insecure memory!
 Please select what kind of key you want:
    (1) RSA and RSA (default)
    (2) DSA and Elgamal
    (3) DSA (sign only)
    (4) RSA (sign only)
 Your selection? 1
 RSA keys may be between 1024 and 4096 bits long.
 What keysize do you want? (2048) 2048 <.>
 Requested keysize is 2048 bits
 Please specify how long the key should be valid.
 	 0 = key does not expire
       <n>  = key expires in n days
       <n>w = key expires in n weeks
       <n>m = key expires in n months
       <n>y = key expires in n years
 Key is valid for? (0) 3y <.>
 Key expires at Wed Nov  4 17:20:20 2015 MST
 Is this correct? (y/N) y
 GnuPG needs to construct a user ID to identify your key.
 
 Real name: Chucky Daemon <.>
 Email address: notreal@example.com
 Comment:
 You selected this USER-ID:
 "Chucky Daemon <notreal@example.com>"
 
 Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
 You need a Passphrase to protect your secret key.
 ....
 
 <.> 2048-bit keys with a three-year expiration provide adequate protection at present (2013-12). http://danielpocock.com/rsa-key-sizes-2048-or-4096-bits[] describes the situation in more detail.
 
 <.> A three year key lifespan is short enough to obsolete keys weakened by advancing computer power, but long enough to reduce key management problems.
 
 <.> Use your real name here, preferably matching that shown on government-issued ID to make it easier for others to verify your identity. Text that may help others identify you can be entered in the `Comment` section.
-+ 
++
 After the email address is entered, a passphrase is requested.
 Methods of creating a secure passphrase are contentious.
 Rather than suggest a single way, here are some links to sites that describe various methods: http://world.std.com/~reinhold/diceware.html[], http://www.iusmentis.com/security/passphrasefaq/[], http://xkcd.com/936/[], http://en.wikipedia.org/wiki/Passphrase[].
 ====
 
 Protect the private key and passphrase.
 If either the private key or passphrase may have been compromised or disclosed, immediately notify mailto:accounts@FreeBSD.org[accounts@FreeBSD.org] and revoke the key.
 
 Committing the new key is shown in <<commit-steps, Steps for New Committers>>.
 
 [[kerberos-ldap]]
 == Kerberos and LDAP web Password for FreeBSD Cluster
 
 The FreeBSD cluster requires a Kerberos password to access certain services.
 The Kerberos password also serves as the LDAP web password, since LDAP is proxying to Kerberos in the cluster.
 Some of the services which require this include:
 
 * https://bugs.freebsd.org/bugzilla[Bugzilla]
 * https://ci.freebsd.org[Jenkins]
 
 To create a new Kerberos account in the FreeBSD cluster, or to reset a Kerberos password for an existing account using a random password generator:
 
 [source,shell]
 ....
 % ssh kpasswd.freebsd.org
 ....
 
 [NOTE]
 ====
 This must be done from a machine outside of the FreeBSD.org cluster.
 ====
 
 A Kerberos password can also be set manually by logging into `freefall.FreeBSD.org` and running:
 
 [source,shell]
 ....
 % kpasswd
 ....
 
 [NOTE]
 ====
 Unless the Kerberos-authenticated services of the FreeBSD.org cluster have been used previously, `Client unknown` will be shown.
 This error means that the `ssh kpasswd.freebsd.org` method shown above must be used first to initialize the Kerberos account.
 ====
 
 [[committer.types]]
 == Commit Bit Types
 
 The FreeBSD repository has a number of components which, when combined, support the basic operating system source, documentation, third party application ports infrastructure, and various maintained utilities.
 When FreeBSD commit bits are allocated, the areas of the tree where the bit may be used are specified.
 Generally, the areas associated with a bit reflect who authorized the allocation of the commit bit.
 Additional areas of authority may be added at a later date: when this occurs, the committer should follow normal commit bit allocation procedures for that area of the tree, seeking approval from the appropriate entity and possibly getting a mentor for that area for some period of time.
 
 [.informaltable]
 [cols="1,1,1", frame="none"]
 |===
 
 |__Committer Type__
 |__Responsible__
 |__Tree Components__
 
 |src
 |core@
 |src/
 
 |doc
 |doceng@
 |doc/, ports/, src/ documentation
 
 |ports
 |portmgr@
 |ports/
 |===
 
 Commit bits allocated prior to the development of the notion of areas of authority may be appropriate for use in many parts of the tree.
 However, common sense dictates that a committer who has not previously worked in an area of the tree seek review prior to committing, seek approval from the appropriate responsible party, and/or work with a mentor.
 Since the rules regarding code maintenance differ by area of the tree, this is as much for the benefit of the committer working in an area of less familiarity as it is for others working on the tree.
 
 Committers are encouraged to seek review for their work as part of the normal development process, regardless of the area of the tree where the work is occurring.
 
 === Policy for Committer Activity in Other Trees
 
 * All committers may modify [.filename]#src/share/misc/committers-*.dot#, [.filename]#src/usr.bin/calendar/calendars/calendar.freebsd#, and [.filename]#ports/astro/xearth/files#.
 * doc committers may commit documentation changes to [.filename]#src# files, such as man pages, READMEs, fortune databases, calendar files, and comment fixes without approval from a src committer, subject to the normal care and tending of commits.
 * Any committer may make changes to any other tree with an "Approved by" from a non-mentored committer with the appropriate bit.
 Mentored committers can provide a "Reviewed by" but not an "Approved by".
 * Committers can acquire an additional bit by the usual process of finding a mentor who will propose them to core, doceng, or portmgr, as appropriate. When approved, they will be added to 'access' and the normal mentoring period will ensue, which will involve a continuing of "Approved by" for some period.
 
 [[git-primer]]
 == Git Primer
 
 [NOTE]
 ====
 this section is a work in progress...
 ====
 
 [[git-basics]]
 === Git basics
 
 There are many primers on how to use Git on the web.
 There's a lot of them (search for "Git primer").
 https://danielmiessler.com/study/git/ and https://gist.github.com/williewillus/068e9a8543de3a7ef80adb2938657b6b are good overviews.
 The Git book is also complete, but much longer https://git-scm.com/book/en/v2.
 There is also this website https://ohshitgit.com/ for common traps and pitfalls of Git, in case you need guidance to fix things up.
 
 This document will assume that you've read through it and will try not to belabor the basics (though it will cover them briefly).
 
 [[git-mini-primer]]
 === Git Mini Primer
 
 This primer is less ambitiously scoped than the old Subversion Primer, but should cover the basics.
 
 ==== Scope
 
 If you want to download FreeBSD, compile it from sources, and generally keep up to date that way, this primer is for you.
 It covers getting the sources, updating the sources, bisecting and touches briefly on how to cope with a few local changes.
 It covers the basics, and tries to give good pointers to more in-depth treatment for when the reader finds the basics insufficient.
 Other sections of this guide cover more advanced topics related to contributing to the project. 
 
 The goal of this section is to highlight those bits of Git needed to track sources.
 They assume a basic understanding of Git.
 There are many primers for Git on the web, but the https://git-scm.com/book/en/v2[Git Book] provides one of the better treatments.
 
 ==== Keeping Current With The FreeBSD src Tree
 [[keeping_current]]
 First step: cloning a tree.
 This downloads the entire tree.
 There are two ways to download.
 Most people will want to do a deep clone of the repository.
 However, there are times when you may wish to do a shallow clone.
 
 ===== Branch names
 The branch names in the new Git repository are similar to the old names.
 For the stable branches, they are stable/X where X is the major release (like 11 or 12).
 The main branch in the new repository is 'main'.
 The main branch in the old GitHub mirror was 'master', but is now 'main'.
 Both reflect the defaults of Git at the time they were created.
 The 'main' branch is the default branch if you omit the '-b branch' or '--branch branch' options below.
 
 ===== Repositories
 Please see the <<admin,Administrative Details>> for the latest information on where to get FreeBSD sources.
 $URL below can be obtained from that page.
 
 Note: The project doesn't use submodules as they are a poor fit for our workflows and development model.
 How we track changes in third-party applications is discussed elsewhere and generally of little concern to the casual user.
 
 ===== Deep Clone
 A deep clone pulls in the entire tree, as well as all the history and branches.
 It is the easiest to do.
 It also allows you to use Git's worktree feature to have all your active branches checked out into separate directories but with only one copy of the repository.
 [source,shell]
 ....
 % git clone -o freebsd $URL -b branch [dir]
 ....
 is how you make a deep clone.
 'branch' should be one of the branches listed in the previous section.
 It is optional if it is the main branch.
 'dir' is an optional directory to place it in (the default will be the name of the repo you are cloning (src, doc, etc)).
 
 You will want a deep clone if you are interested in the history, plan on making local changes, or plan on working on more than one branch.
 It is the easiest to keep up to date as well.
 If you are interested in the history, but are working with only one branch and are short on space, you can also use --single-branch to only download the one branch
 (though some merge commits will not reference the merged-from branch which may be important for some users who are interested in detailed versions of history).
 
 ===== Shallow Clone
 
 A shallow clone copies just the most current code, but none or little of the history.
 This can be useful when you need to build a specific revision of FreeBSD, or when you are just starting out and plan to track the tree more fully.
 You can also use it to limit history to only so many revisions.
 However, see below for a significant limitation of this approach.
 
 [source,shell]
 ....
 % git clone -o freebsd -b branch --depth 1 $URL [dir]
 ....
 
 This clones the repository, but only has the most recent version in the repository.
 The rest of the history is not downloaded.
 Should you change your mind later, you can do 'git fetch --unshallow' to get the old history.
 
 [WARNING]
 ====
 When you make a shallow clone, you will lose the commit count in your uname output.
 This can make it more difficult to determine if your system needs to be updated when a security advisory is issued.
 ====
 
 ===== Building
 
 Once you've downloaded, building is done as described in the handbook,
 eg:
 [source,shell]
 ....
 % cd src
 % make buildworld
 % make buildkernel
 % make installkernel
 % make installworld
 ....
 so that won't be covered in depth here.
 
 If you want to build a custom kernel, link:{handbook}#kernelconfig[the kernel config section] of the FreeBSD Handbook recommends creating a file MYKERNEL under sys/${ARCH}/conf with your changes against GENERIC.
 To have MYKERNEL disregarded by Git, it can be added to .git/info/exclude.
 
 ===== Updating
 
 To update both types of trees uses the same commands.
 This pulls in all the revisions since your last update.
 [source,shell]
 ....
 % git pull --ff-only
 ....
 will update the tree.
 In Git, a 'fast forward' merge is one that only needs to set a new branch pointer and doesn't need to re-create the commits.
 By always doing a 'fast forward' merge/pull, you'll ensure that you have an exact copy of the FreeBSD tree.
 This will be important if you want to maintain local patches.
 
 See below for how to manage local changes.
 The simplest is to use --autostash on the 'git pull' command, but more sophisticated options are available.
 
 ==== Selecting a Specific Version
 
 In Git, the 'git checkout' checks out both branches and specific versions.
 Git's versions are the long hashes rather than a sequential number.
 
 When you checkout a specific version, just specify the hash you want on the command line (the git log command can help you decide which hash you might want):
 [source,shell]
 ....
 % git checkout 08b8197a74
 ....
 and you have that checked out.
 You will be greeted with a message similar to the following:
 [source,shell]
 ....
 Note: checking out '08b8197a742a96964d2924391bf9fdfeb788865d'.
 
 You are in a 'detached HEAD' state. You can look around, make experimental
 changes and commit them, and you can discard any commits you make in this
 state without impacting any branches by performing another checkout.
 
 If you want to create a new branch to retain commits you create, you may
 do so (now or later) by using -b with the checkout command again. Example:
 
   git checkout -b <new-branch-name>
 
 HEAD is now at 08b8197a742a hook gpiokeys.4 to the build
 ....
 where the last line is generated from the hash you are checking out and the first line of the commit message from that revision.
 The hash can be abbreviated to the shortest unique length.
 Git itself is inconsistent about how many digits it displays.
 
 ==== Bisecting
 Sometimes, things go wrong.
 The last version worked, but the one you just updated to does not.
 A developer may ask you to bisect the problem to track down which commit caused the regression.
 
 Git makes bisecting changes easy with a powerful 'git bisect' command.
 Here's a brief outline of how to use it.
 For more information, you can view https://www.metaltoad.com/blog/beginners-guide-git-bisect-process-elimination or https://git-scm.com/docs/git-bisect for more details.
 The man git-bisect page is good at describing what can go wrong, what to do when versions won't build, when you want to use terms other than 'good' and 'bad', etc, none of which will be covered here.
 
 `git bisect start` will start the bisection process.
 Next, you need to tell a range to go through.
 'git bisect good XXXXXX' will tell it the working version and 'git bisect bad XXXXX' will tell it the bad version.
 The bad version will almost always be HEAD (a special tag for what you have checked out).
 The good version will be the last one you checked out.
 
 [TIP]
 ====
 If you want to know the last version you checked out, you should use 'git reflog':
 [source,shell]
 ....
 5ef0bd68b515 (HEAD -> main, freebsd/main, freebsd/HEAD) HEAD@{0}: pull --ff-only: Fast-forward
 a8163e165c5b (upstream/main) HEAD@{1}: checkout: moving from b6fb97efb682994f59b21fe4efb3fcfc0e5b9eeb to main
 ...
 ....
 shows me moving the working tree to the main branch (a816...) and then updating from upstream (to 5ef0...).
 In this case, bad would be HEAD (or 5rf0bd68) and good would be a8163e165.
 As you can see from the output, HEAD@{1} also often works, but isn't foolproof if you have done other things to your Git tree after updating, but before you discover the need to bisect.
 ====
 
 Set the 'good' version first, then set the bad (though the order doesn't matter).
 When you set the bad version, it will give you some statistics on the process:
 [source,shell]
 ....
 % git bisect start
 % git bisect good a8163e165c5b
 % git bisect bad HEAD
 Bisecting: 1722 revisions left to test after this (roughly 11 steps)
 [c427b3158fd8225f6afc09e7e6f62326f9e4de7e] Fixup r361997 by balancing parens.  Duh.
 ....
 
 You would then build/install that version.
 If it's good you'd type 'git bisect good' otherwise 'git bisect bad'.
 If the version doesn't compile, type 'git bisect skip'.
 You will get a similar message to the above after each step.
 When you are done, report the bad version to the developer (or fix the bug yourself and send a patch).
 'git bisect reset' will end the process and return you back to where you started (usually tip of main).
 Again, the git-bisect manual (linked above) is a good resource for when things go wrong or for unusual cases.
 
 [[git-gpg-signing]]
 ==== Signing the commits, tags, and pushes, with GnuPG
 
 Git knows how to sign commits, tags, and pushes.
 When you sign a Git commit or a tag, you can prove that the code you submitted came from you and wasn't altered while you were transferring it.
 You also can prove that you submitted the code and not someone else.
 
 A more in-depth documentation on signing commits and tags can be found in the https://git-scm.com/book/en/v2/Git-Tools-Signing-Your-Work[Git Tools - Signing Your Work] chapter of the Git's book.
 
 The rationale behind signing pushes can be found in the https://github.com/git/git/commit/a85b377d0419a9dfaca8af2320cc33b051cbed04[commit that introduced the feature].
 
 The best way is to simply tell Git you always want to sign commits, tags, and pushes.
 You can do this by setting a few configuration variables:
 
 [source,shell]
 ....
 % git config --add user.signingKey=LONG-KEY-ID
 % git config --add commit.gpgSign=true
 % git config --add tag.gpgSign=true
 % git config --add push.gpgSign=if-asked
 ....
 
 // push.gpgSign should probably be set to `yes` once we enable it, or be set with --global, so that it is enabled for all repositories.
 
 [NOTE]
 ======
 To avoid possible collisions, make sure you give a long key id to Git.
 You can get the long id with: `gpg --list-secret-keys --keyid-format LONG`.
 ======
 
 [TIP]
 ======
 To use specific subkeys, and not have GnuPG to resolve the subkey to a primary key, attach `!` to the key.
 For example, to encrypt for the subkey `DEADBEEF`, use `DEADBEEF!`.
 ======
 
 ===== Verifying signatures
 
 Commit signatures can be verified by running either `git verify-commit <commit hash>`, or `git log --show-signature`.
 
 Tag signatures can be verifed with `git verity-tag <tag name>`, or `git tag -v <tag name>`.
 
 ////
 Commented out for now until we decide what to do.
 
 Git pushes are a bit different, they live in a special ref in the repository.
 TODO: write how to verify them
 
 ////
 
 ==== Ports Considerations
 The ports tree operates the same way.
 The branch names are different and the repositories are in different locations.
 
 The cgit repository web interface for use with web browsers is at https://cgit.FreeBSD.org/ports/ .
 The production Git repository is at https://git.FreeBSD.org/ports.git and at ssh://anongit@git.FreeBSD.org/ports.git (or anongit@git.FreeBSD.org:ports.git).
 
 There is also a mirror on GitHub, see link:{handbook}mirrors/#mirrors[External mirrors] for an overview.
 The 'current' branch is 'main' .
 The quarterly branches are named 'yyyyQn' for year 'yyyy' and quarter 'n'.
 
 ===== Commit message formats
 
 A hook is available in the ports repository to help you write up your commit messages in https://cgit.freebsd.org/ports/tree/.hooks/prepare-commit-msg[.hooks/prepare-commit-message].
 It can be enabled by running ``git config --add core.hooksPath .hooks``.
 
 The main point being that a commit message should be formatted in the following way:
 
 ....
 category/port: Summary.
 
 Description of why the changes where made.
 
 PR:	    12345
 ....
 
 [IMPORTANT]
 ====
 The first line is the subject of the commit, it contains what port was changed, and a summary of the commit.
 It should contain 50 characters or less.
 
 A blank line should separate it from the rest of the commit message.
 
 The rest of the commit message should be wrapped at the 72 characters boundary.
 
 Another blank line should be added if there are any metadata fields, so that they are easily distinguishable from the commit message.
 ====
 
 ==== Managing Local Changes
 This section addresses tracking local changes.
 If you have no local changes, you can stop reading now (it is the last section and OK to skip).
 
 One item that is important for all of them: all changes are local until pushed.
 Unlike Subversion, Git uses a distributed model.
 For users, for most things, there is very little difference.
 However, if you have local changes, you can use the same tool to manage them as you use to pull in changes from FreeBSD.
 All changes that you have not pushed are local and can easily be modified (git rebase, discussed below does this).
 
 ===== Keeping local changes
 The simplest way to keep local changes (especially trivial ones) is to use 'git stash'.
 In its simplest form, you use 'git stash' to record the changes (which pushes them onto the stash stack).
 Most people use this to save changes before updating the tree as described above.
 They then use 'git stash apply' to re-apply them to the tree.
 The stash is a stack of changes that can be examined with 'git stash list'.
 The git-stash man page (https://git-scm.com/docs/git-stash) has all the details.
 
 This method is suitable when you have tiny tweaks to the tree.
 When you have anything non trivial, you'll likely be better off keeping a local branch and rebasing.
 Stashing is also integrated with the 'git pull' command: just add '--autostash' to the command line.
 
 ===== Keeping a local branch
 [[keeping_a_local_branch]]
 It is much easier to keep a local branch with Git than Subversion.
 In Subversion you need to merge the commit, and resolve the conflicts.
 This is manageable, but can lead to a convoluted history that's hard to upstream should that ever be necessary, or hard to replicate if you need to do so.
 Git also allows one to merge, along with the same problems.
 That's one way to manage the branch, but it's the least flexible.
 
 In addition to merging, Git supports the concept of 'rebasing' which avoids these issues.
 The 'git rebase' command replays all the commits of a branch at a newer location on the parent branch.
 We will cover the most common scenarios that arise using it.
 
 ====== Create a branch
 
 Let's say you want to make a change to FreeBSD's ls command to never, ever do color.
 There are many reasons to do this, but this example will use that as a baseline.
 The FreeBSD ls command changes from time to time, and you'll need to cope with those changes.
 Fortunately, with Git rebase it usually is automatic.
 [source,shell]
 ....
 % cd src
 % git checkout main
 % git checkout -b no-color-ls
 % cd bin/ls
 % vi ls.c     # hack the changes in
 % git diff    # check the changes
 diff --git a/bin/ls/ls.c b/bin/ls/ls.c
 index 7378268867ef..cfc3f4342531 100644
 --- a/bin/ls/ls.c
 +++ b/bin/ls/ls.c
 @@ -66,6 +66,7 @@ __FBSDID("$FreeBSD$");
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
 +#undef COLORLS
  #ifdef COLORLS
  #include <termcap.h>
  #include <signal.h>
 % # these look good, make the commit...
 % git commit ls.c
 ....
 
 The commit will pop you into an editor to describe what you've done.
 Once you enter that, you have your own **local** branch in the Git repo.
 Build and install it like you normally would, following the directions in the handbook.
 Git differs from other version control systems in that you have to tell it explicitly which files to commit.
 I have opted to do it on the commit command line, but you can also do it with 'git add' which many of the more in depth tutorials cover.
 
 ====== Time to update
 When it is time to bring in a new version, it is almost the same as w/o the branches.
 You would update like you would above, but there is one extra command before you update, and one after.
 The following assumes you are starting with an unmodified tree.
 It is important to start rebasing operations with a clean tree (Git usually requires this).
 
 [source,shell]
 ....
 % git checkout main
 % git pull --no-ff
 % git rebase -i main no-color-ls
 ....
 
 This will bring up an editor that lists all the commits in it.
 For this example, do not change it at all.
 This is typically what you are doing while updating the baseline (though you also use the Git rebase command to curate the commits you have in the branch).
 
 Once you are done with the above, you have to move the commits to ls.c forward from the old version of FreeBSD to the newer one.
 
 Sometimes there are merge conflicts.
 That is OK.
 Do not panic.
 Instead, handle them the same as any other merge conflicts.
 To keep it simple, I will just describe a common issue that may arise.
 A pointer to a more complete treatment can be found at the end of this section.
 
 Let's say the includes changes upstream in a radical shift to terminfo as well as a name change for the option.
 When you updated, you might see something like this:
 [source,shell]
 ....
 Auto-merging bin/ls/ls.c
 CONFLICT (content): Merge conflict in bin/ls/ls.c
 error: could not apply 646e0f9cda11... no color ls
 Resolve all conflicts manually, mark them as resolved with
 "git add/rm <conflicted_files>", then run "git rebase --continue".
 You can instead skip this commit: run "git rebase --skip".
 To abort and get back to the state before "git rebase", run "git rebase --abort".
 Could not apply 646e0f9cda11... no color ls
 ....
 which looks scary.
 If you bring up an editor, you will see it is a typical 3-way merge conflict resolution that you may be familiar with from other source code systems (the rest of ls.c has been omitted):
 [source,shell]
 ....
 <<<<<<< HEAD
 #ifdef COLORLS_NEW
 #include <terminfo.h>
 =======
 #undef COLORLS
 #ifdef COLORLS
 #include <termcap.h>
 >>>>>>> 646e0f9cda11... no color ls
 ....
 The new code is first, and your code is second.
 The right fix here is to just add a #undef COLORLS_NEW before #ifdef and then delete the old changes:
 [source,shell]
 ....
 #undef COLORLS_NEW
 #ifdef COLORLS_NEW
 #include <terminfo.h>
 ....
 save the file.
 The rebase was interrupted, so you have to complete it:
 [source,shell]
 ....
 % git add ls.c
 % git rebase --continue
 ....
 
 which tells Git that ls.c has been fixed and to continue the rebase operation.
 Since there was a conflict, you will get kicked into the editor to update the commit message if necessary.
 If the commit message is still accurate, just exit the editor.
 
 If you get stuck during the rebase, do not panic.
 git rebase --abort will take you back to a clean slate.
 It is important, though, to start with an unmodified tree.
 An aside: The above mentioned 'git reflog' comes in handy here, as it will have a list of all the (intermediate) commits that you can view or inspect or cherry-pick.
 
 For more on this topic, https://www.freecodecamp.org/news/the-ultimate-guide-to-git-merge-and-git-rebase/ provides a rather extensive treatment.
 It is a good resource for issues that arise occasionally but are too obscure for this guide.
 
 ===== Switching to a Different FreeBSD Branch
 If you wish to shift from stable/12 to the current branch.
 If you have a deep clone, the following will suffice:
 [source,shell]
 ....
 % git checkout main
 % # build and install here...
 ....
 If you have a local branch, though, there are one or two caveats.
 First, rebase will rewrite history, so you will likely want to do something to save it.
 Second, jumping branches tends to cause more conflicts.
 If we pretend the example above was relative to stable/12, then to move to main, I'd suggest the following:
 [source,shell]
 ....
 % git checkout no-color-ls
 % git checkout -b no-color-ls-stable-12   # create another name for this branch
 % git rebase -i stable/12 no-color-ls --onto main
 ....
 
 What the above does is checkout no-color-ls.
 Then create a new name for it (no-color-ls-stable-12) in case you need to get back to it.
 Then you rebase onto the main branch.
 This will find all the commits to the current no-color-ls branch (back to where it meets up with the stable/12 branch) and then it will
 replay them onto the main branch creating a new no-color-ls branch there (which is why I had you create a place holder name).
 
 ===== Migrating from an existing Git clone
 If you have work based on a previous Git conversion or a locally running git-svn conversion, migrating to new repository can encounter problems because Git has no knowledge about the connection between the two.
 
 When you have only a few local changes, the easiest way would be to cherry-pick those changes to the new base:
 [source,shell]
 ....
 % git checkout main
 % git cherry-pick old_branch..your_branch
 ....
 Or alternatively, do the same thing with rebase:
 [source,shell]
 ....
 % git rebase --onto main master your_branch
 ....
 
 If you do have a lot of changes, you would probably want to perform a merge instead.
 The idea is to create a merge point that consolidates the history of the old_branch, and the new FreeBSD repository (main).
 
 You can find out by looking up the same commit that are found on both parents:
 [source,shell]
 ....
 % git show old_branch
 ....
 You will see a commit message, now search for that in the new branch:
 [source,shell]
 ....
 % git log --grep="commit message on old_branch" freebsd/main
 ....
 You would help locate the commit hash on the new main branch, create a helper branch (in the example we call it 'stage') from that hash:
 [source,shell]
 ....
 % git checkout -b stage _hash_found_from_git_log_
 ....
 Then perform a merge of the old branch:
 [source,shell]
 ....
 % git merge -s ours -m "Mark old branch as merged" old_branch
 ....
 With that, it's possible to merge your work branch or the main branch in any order without problem.
 Eventually, when you are ready to commit your work back to main, you can perform a rebase to main, or do a squash commit by combining everything into one commit.
 
 [[mfc-with-git]]
 === MFC (Merge From Current) Procedures
 ==== Summary
 
 MFC workflow can be summarized as `git cherry-pick -x` plus `git commit --amend` to adjust the commit message.
 For multiple commits, use `git rebase -i` to squash them together and edit the commit message.
 
 ==== Single commit MFC
 
 [source,shell]
 ....
 % git checkout stable/X
 % git cherry-pick -x $HASH --edit
 ....
 
 For MFC commits, for example a vendor import, you would need to specify one parent for cherry-pick purposes.
 Normally, that would be the "first parent" of the branch you are cherry-picking from, so:
 
 [source,shell]
 ....
 % git checkout stable/X
 % git cherry-pick -x $HASH -m 1 --edit
 ....
 
 If things go wrong, you'll either need to abort the cherry-pick with `git cherry-pick --abort` or fix it up and do a `git cherry-pick --continue`.
 
 Once the cherry-pick is finished, push with `git push`.
 If you get an error due to losing the commit race, use `git pull --rebase` and try to push again.
 
 ==== MFC to RELENG branch
 
 MFCs to branches that require approval require a bit more care.
 The process is the same for either a typical merge or an exceptional direct commit.
 
 * Merge or direct commit to the appropriate `stable/X` branch first before merging to the `releng/X.Y` branch.
 * Use the hash that's in the `stable/X` branch for the MFC to `releng/X.Y` branch.
 * Leave both "cherry picked from" lines in the commit message.
 * Be sure to add the `Approved by:` line when you are in the editor.
 
 [source,shell]
 ....
 % git checkout releng/13.0
 % git cherry-pick -x $HASH --edit
 ....
 
 If you forget to to add the `Approved by:` line, you can do a `git commit --amend` to edit the commit message before you push the change.
 
 ==== Multiple commit MFC
 
 [source,shell]
 ....
 % git checkout -b tmp-branch stable/X
 % for h in $HASH_LIST; do git cherry-pick -x $h; done
 % git rebase -i stable/X
 # mark each of the commits after the first as 'squash'
 # Update the commit message to reflect all elements of commit, if necessary.
 # Be sure to retain the "cherry picked from" lines.
 % git push freebsd HEAD:stable/X
 ....
 
 If the push fails due to losing the commit race, rebase and try again:
 
 [source,shell]
 ....
 % git checkout stable/X
 % git pull
 % git checkout tmp-branch
 % git rebase stable/X
 % git push freebsd HEAD:stable/X
 ....
 
 Once the MFC is complete, you can delete the temporary branch:
 
 [source,shell]
 ....
 % git checkout stable/X
 % git branch -d tmp-branch
 ....
 
 ==== MFC a vendor import
 
 Vendor imports are the only thing in the tree that creates a merge commit in the main line.
 Cherry picking merge commits into stable/XX presents an additional difficulty because there are two parents for a merge commit.
 Generally, you'll want the first parent's diff since that's the diff to mainline (though there may be some exceptions).
 
 [source,shell]
 ....
 % git cherry-pick -x -m 1 $HASH
 ....
 is typically what you want.
 This will tell cherry-pick to apply the correct diff.
 
 There are some, hopefully, rare cases where it's possible that the mainline was merged backwards by the conversion script.
 Should that be the case (and we've not found any yet), you'd change the above to '-m 2' to pickup the proper parent.
 Just do
 [source,shell]
 ....
 % git cherry-pick --abort
 % git cherry-pick -x -m 2 $HASH
 ....
 to do that. The `--aboort` will cleanup the failed first attempt.
 
 ==== Redoing a MFC
 
 If you do a MFC, and it goes horribly wrong and you want to start over,
 then the easiest way is to use `git reset --hard` like so:
 [source,shell]
 ....
 % git reset --hard freebsd/stable/12
 ....
 though if you have some revs you want to keep, and others you don't,
 using 'git rebase -i' is better.
 
 ==== Considerations when MFCing
 
 When committing source commits to stable and releng branches, we have the following goals:
 
 * Clearly mark direct commits distinct from commits that land a change from another branch.
 * Avoid introducing known breakage into stable and releng branches.
 * Allow developers to determine which changes have or have not been landed from one branch to another.
 
 With Subversion, we used the following practices to achieve these goals:
 
 * Using 'MFC' and 'MFS' tags to mark commits that merged changes from another branch.
 * Squashing fixup commits into the main commit when merging a change.
 * Recording mergeinfo so that `svn mergeinfo --show-revs` worked.
 
 With Git, we will need to use different strategies to achieve the same goals.
 This document aims to define best practices when merging source commits using Git that achieve these goals.
 In general, we aim to use Git's native support to achieve these goals rather than enforcing practices built on Subversion's model.
 
 One general note: due to technical differences with Git, we will not be using Git "merge commits" (created via `git merge`) in stable or releng branches.
 Instead, when this document refers to "merge commits", it means a commit originally made to `main` that is replicated or "landed" to a stable branch, or a commit from a stable branch that is replicated to a releng branch with some variation of `git cherry-pick`.
 
 ==== Finding Eligible Hashes to MFC
 
 Git provides some built-in support for this via the `git cherry` and `git log --cherry` commands.
 These commands compare the raw diffs of commits (but not other metadata such as log messages) to determine if two commits are identical.
 This works well when each commit from head is landed as a single commit to a stable branch, but it falls over if multiple commits from main are squashed together as a single commit to a stable branch.
 
 There are a few options for resolving this:
 
 1. We could ban squashing of commits and instead require that committers stage all of the fixup / follow-up commits to stable into a single push.
 This would still achieve the goal of stability in stable and releng branches since pushes are atomic and users doing a simple pull will never end up with a tree that has the main commit without the fixup(s).
 `git bisect` is also able to cope with this model via `git bisect skip`.
 
 2. We could adopt a consistent style for describing MFCs and write our own tooling to wrap around `git cherry` to determine the list of eligible commits.
 A simple approach here might be to use the syntax from `git cherry-pick -x`, but require that a squashed commit list all of the hashes (one line per hash) at the end of the commit message.
 Developers could do this by using `git cherry-pick -x` of each individual commit into a branch and then use `git rebase` to squash the commits down into a single commit, but collecting the `-x` annotations at the end of the landed commit log.
 
 ==== Commit message standards
 ===== Marking MFCs
 
 The project has adopted the following practice for marking MFCs:
 
 * Use the `-x` flag with `git cherry-pick`.  This adds a line to the commit message that includes the hash of the original commit when merging. Since it is added by Git directly, committers do not have to manually edit the commit log when merging.
 
 When merging multiple commits, keep all the "cherry picked from" lines.
 
 ===== Trim Metadata?
 
 One area that was not clearly documented with Subversion (or even CVS) is how to format metadata in log messages for MFC commits.
 Should it include the metadata from the original commit unchanged, or should it be altered to reflect information about the MFC commit itself?
 
 Historical practice has varied, though some of the variance is by field.
 For example, MFCs that are relevant to a PR generally include the PR field in the MFC so that MFC commits are included in the bug tracker's audit trail.
 Other fields are less clear.
 For example, Phabricator shows the diff of the last commit tagged to a review, so including Phabricator URLs replaces the `main` commit with the landed commits.
 The list of reviewers is also not clear.
 If a reviewer has approved a change to `main`, does that mean they have approved the MFC commit?  Is that true if it's identical code only, or with merely trivial reworkes? It's clearly not true for more extensive reworks.
 Even for identical code what if the commit doesn't conflict but introduces an ABI change?  A reviewer may have ok'd a commit for `main` due to the ABI breakage but may not approve of merging the same commit as-is.
 One will have to use one's best judgement until clear guidelines can be agreed upon.
 
 For MFCs regulated by re@, new metadata fields are added, such as the Approved by tag for approved commits.
 This new metadata will have to be added via `git commit --amend` or similar after the original commit has been reviewed and approved.
 We may also want to reserve some metadata fields in MFC commits such as Phabricator URLs for use by re@ in the future.
 
 Preserving existing metadata provides a very simple workflow.
 Developers can just use `git cherry-pick -x` without having to edit the log message.
 
 If instead we choose to adjust metadata in MFCs, developers will have to edit log messages explicitly via the use of `git cherry-pick --edit` or `git commit --amend`.
 However, as compared to svn, at least the existing commit message can be pre-populated and metadata fields can be added or removed without having to re-enter the entire commit message.
 
 The bottom line is that developers will likely need to curate their commit message for MFCs that are non-trivial.
 
 ==== Examples
 
 ===== Merging a Single Subversion Commit
 
 This walks through the process of merging a commit to stable/12 that was originally committed to head in Subversion.
 In this case, the original commit is r368685.
 
 The first step is to map the Subversion commit to a Git hash.
 Once you have fetched refs/notes/commits, you can pass the revision number to `git log --grep`:
 
 [source,shell]
 ....
 % git log main --grep 368685
 commit ce8395ecfda2c8e332a2adf9a9432c2e7f35ea81
 Author: John Baldwin <jhb@FreeBSD.org>
 Date:   Wed Dec 16 00:11:30 2020 +0000
 
     Use the 't' modifier to print a ptrdiff_t.
 
     Reviewed by:    imp
     Obtained from:  CheriBSD
     Sponsored by:   DARPA
     Differential Revision:  https://reviews.freebsd.org/D27576
 
 Notes:
     svn path=/head/; revision=368685
 ....
 
 Next, MFC the commit to a `stable/12` checkout:
 
 [source,shell]
 ....
 git checkout stable/12
 git cherry-pick -x ce8395ecfda2c8e332a2adf9a9432c2e7f35ea81 --edit
 ....
 
 Git will invoke the editor.
 Use this to remove the metadata that only applied to the original commit (Phabricator URL and Reviewed by).
 After the editor saves the updated log message, Git completes the commit:
 
 [source,shell]
 ....
 [stable/12 3e3a548c4874] Use the 't' modifier to print a ptrdiff_t.
  Date: Wed Dec 16 00:11:30 2020 +0000
  1 file changed, 1 insertion(+), 1 deletion(-)
 ....
 
 The contents of the MFCd commit can be examined via `git show`:
 
 [source,shell]
 ....
 % git show
 commit 3e3a548c487450825679e4bd63d8d1a67fd8bd2d (HEAD -> stable/12)
 Author: John Baldwin <jhb@FreeBSD.org>
 Date:   Wed Dec 16 00:11:30 2020 +0000
 
     Use the 't' modifier to print a ptrdiff_t.
 
     Obtained from:  CheriBSD
     Sponsored by:   DARPA
 
     (cherry picked from commit ce8395ecfda2c8e332a2adf9a9432c2e7f35ea81)
 
 diff --git a/sys/compat/linuxkpi/common/include/linux/printk.h b/sys/compat/linuxkpi/common/include/linux/printk.h
 index 31802bdd2c99..e6510e9e9834 100644
 --- a/sys/compat/linuxkpi/common/include/linux/printk.h
 +++ b/sys/compat/linuxkpi/common/include/linux/printk.h
 @@ -68,7 +68,7 @@ print_hex_dump(const char *level, const char *prefix_str,
                         printf("[%p] ", buf);
                         break;
                 case DUMP_PREFIX_OFFSET:
 -                       printf("[%p] ", (const char *)((const char *)buf -
 +                       printf("[%#tx] ", ((const char *)buf -
                             (const char *)buf_old));
                         break;
                 default:
 ....
 
 The MFC commit can now be published via `git push`
 
 [source,shell]
 ....
 % git push freebsd
 Enumerating objects: 17, done.
 Counting objects: 100% (17/17), done.
 Delta compression using up to 4 threads
 Compressing objects: 100% (7/7), done.
 Writing objects: 100% (9/9), 817 bytes | 204.00 KiB/s, done.
 Total 9 (delta 5), reused 1 (delta 1), pack-reused 0
 To gitrepo-dev.FreeBSD.org:src.git
    525bd9c9dda7..3e3a548c4874  stable/12 -> stable/12
 ....
 
 ===== Merging a Single Subversion Commit with a Conflict
 
 This example is similar to the previous example except that the commit in question encounters a merge conflict.
 In this case, the original commit is r368314.
 
 As above, the first step is to map the Subversion commit to a Git hash:
 
 [source,shell]
 ....
 % git log main --grep 368314
 commit 99963f5343a017e934e4d8ea2371a86789a46ff9
 Author: John Baldwin <jhb@FreeBSD.org>
 Date:   Thu Dec 3 22:01:13 2020 +0000
 
     Don't transmit mbufs that aren't yet ready on TOE sockets.
 
     This includes mbufs waiting for data from sendfile() I/O requests, or
     mbufs awaiting encryption for KTLS.
 
     Reviewed by:    np
     MFC after:      2 weeks
     Sponsored by:   Chelsio Communications
     Differential Revision:  https://reviews.freebsd.org/D27469
 
 Notes:
     svn path=/head/; revision=368314
 ....
 
 Next, MFC the commit to a `stable/12` checkout:
 
 [source,shell]
 ....
 % git checkout stable/12
 % git cherry-pick -x 99963f5343a017e934e4d8ea2371a86789a46ff9 --edit
 Auto-merging sys/dev/cxgbe/tom/t4_cpl_io.c
 CONFLICT (content): Merge conflict in sys/dev/cxgbe/tom/t4_cpl_io.c
 warning: inexact rename detection was skipped due to too many files.
 warning: you may want to set your merge.renamelimit variable to at least 7123 and retry the command.
 error: could not apply 99963f5343a0... Don't transmit mbufs that aren't yet ready on TOE sockets.
 hint: after resolving the conflicts, mark the corrected paths
 hint: with 'git add <paths>' or 'git rm <paths>'
 hint: and commit the result with 'git commit'
 ....
 
 In this case, the commit encountered a merge conflict in sys/dev/cxge/tom/t4_cpl_io.c as kernel TLS is not present in stable/12.
 Note that Git does not invoke an editor to adjust the commit message due to the conflict.
 `git status` confirms that this file has merge conflicts:
 
 [source,shell]
 ....
 % git status
 On branch stable/12
 Your branch is up to date with 'upstream/stable/12'.
 
 You are currently cherry-picking commit 99963f5343a0.
   (fix conflicts and run "git cherry-pick --continue")
   (use "git cherry-pick --skip" to skip this patch)
   (use "git cherry-pick --abort" to cancel the cherry-pick operation)
 
 Unmerged paths:
   (use "git add <file>..." to mark resolution)
         both modified:   sys/dev/cxgbe/tom/t4_cpl_io.c
 
 no changes added to commit (use "git add" and/or "git commit -a")
 ....
 
 After editing the file to resolve the conflict, `git status` shows the conflict as resolved:
 
 [source,shell]
 ....
 % git status
 On branch stable/12
 Your branch is up to date with 'upstream/stable/12'.
 
 You are currently cherry-picking commit 99963f5343a0.
   (all conflicts fixed: run "git cherry-pick --continue")
   (use "git cherry-pick --skip" to skip this patch)
   (use "git cherry-pick --abort" to cancel the cherry-pick operation)
 
 Changes to be committed:
         modified:   sys/dev/cxgbe/tom/t4_cpl_io.c
 ....
 
 The cherry-pick can now be completed:
 
 [source,shell]
 ....
 % git cherry-pick --continue
 ....
 
 Since there was a merge conflict, Git invokes the editor to adjust the commit message.
 Trim the metadata fields from the commit log from the original commit to head and save the updated log message.
 
 The contents of the MFC commit can be examined via `git show`:
 
 [source,shell]
 ....
 % git show
 commit 525bd9c9dda7e7c7efad2d4570c7fd8e1a8ffabc (HEAD -> stable/12)
 Author: John Baldwin <jhb@FreeBSD.org>
 Date:   Thu Dec 3 22:01:13 2020 +0000
 
     Don't transmit mbufs that aren't yet ready on TOE sockets.
     
     This includes mbufs waiting for data from sendfile() I/O requests, or
     mbufs awaiting encryption for KTLS.
 
     Sponsored by:   Chelsio Communications
 
     (cherry picked from commit 99963f5343a017e934e4d8ea2371a86789a46ff9)
 
 diff --git a/sys/dev/cxgbe/tom/t4_cpl_io.c b/sys/dev/cxgbe/tom/t4_cpl_io.c
 index 8e8c2b8639e6..43861f10b689 100644
 --- a/sys/dev/cxgbe/tom/t4_cpl_io.c
 +++ b/sys/dev/cxgbe/tom/t4_cpl_io.c
 @@ -746,6 +746,8 @@ t4_push_frames(struct adapter *sc, struct toepcb *toep, int drop)
                 for (m = sndptr; m != NULL; m = m->m_next) {
                         int n;
  
 +                       if ((m->m_flags & M_NOTAVAIL) != 0)
 +                               break;
                         if (IS_AIOTX_MBUF(m))
                                 n = sglist_count_vmpages(aiotx_mbuf_pages(m),
                                     aiotx_mbuf_pgoff(m), m->m_len);
 @@ -821,8 +823,9 @@ t4_push_frames(struct adapter *sc, struct toepcb *toep, int drop)
  
                 /* nothing to send */
                 if (plen == 0) {
 -                       KASSERT(m == NULL,
 -                           ("%s: nothing to send, but m != NULL", __func__));
 +                       KASSERT(m == NULL || (m->m_flags & M_NOTAVAIL) != 0,
 +                           ("%s: nothing to send, but m != NULL is ready",
 +                           __func__));
                         break;
                 }
  
 @@ -910,7 +913,7 @@ t4_push_frames(struct adapter *sc, struct toepcb *toep, int drop)
                 toep->txsd_avail--;
  
                 t4_l2t_send(sc, wr, toep->l2te);
 -       } while (m != NULL);
 +       } while (m != NULL && (m->m_flags & M_NOTAVAIL) == 0);
  
         /* Send a FIN if requested, but only if there's no more data to send */
         if (m == NULL && toep->flags & TPF_SEND_FIN)
 ....
 
 The MFC commit can now be published via `git push`
 
 [source,shell]
 ....
 git push freebsd
 Enumerating objects: 13, done.
 Counting objects: 100% (13/13), done.
 Delta compression using up to 4 threads
 Compressing objects: 100% (7/7), done.
 Writing objects: 100% (7/7), 819 bytes | 117.00 KiB/s, done.
 Total 7 (delta 6), reused 0 (delta 0), pack-reused 0
 To gitrepo.FreeBSD.org:src.git
    f4d0bc6aa6b9..525bd9c9dda7  stable/12 -> stable/12
 ....
 
 [[vendor-import-git]]
 === Vendor Imports with Git
 
 This section describes the vendor import procedure with Git in detail.
 
 ==== Branch naming convention
 
 All vendor branches and tags start with `vendor/`. These branches and tags are visible by default.
 
 [NOTE]
 ====
 This chapter follows the convention that the `freebsd` origin is the origin name for the official FreeBSD Git repository.
 If you use a different convention, replace `freebsd` with the name you use instead in the examples below.
 ====
 
 We will explore an example for updating NetBSD's mtree that is in our tree.
 The vendor branch for this is `vendor/NetBSD/mtree`.
 
 ==== Updating an old vendor import
 
 The vendor trees usually have only the subset of the third-party software that is appropriate to FreeBSD.
 These trees are usually tiny in comparison to the FreeBSD tree.
 Git worktrees are thus quite small and fast and the preferred method to use.
 Make sure that whatever directory you choose below (the `../mtree`) does not currently exist.
 
 [source,shell]
 ....
 % git worktree add ../mtree vendor/NetBSD/mtree
 ....
 
 ==== Update the Sources in the Vendor Branch
 
 Prepare a full, clean tree of the vendor sources. Import everything but merge only what is needed.
 
 This example assumes the NetBSD checked out from their GitHub mirror in `~/git/NetBSD`.
 Note that "upstream" might have added or removed files, so we want to make sure deletions are propagated as well.
 rsync(1) is commonly installed, so I'll use that.
 
 [source,shell]
 ....
 % cd ../mtree
 % rsync -va --del --exclude=".git" ~/git/NetBSD/usr.sbin/mtree/ .
 % git add -A
 % git status
 ...
 % git diff --staged
 ...
 % git commit -m"Vendor import of NetBSD's mtree at 2020-12-11"
 [vendor/NetBSD/mtree 8e7aa25fcf1] Vendor import of NetBSD's mtree at 2020-12-11
  7 files changed, 114 insertions(+), 82 deletions(-)
 % git tag -a vendor/NetBSD/mtree/20201211
 ....
 
 Note: I run the `git diff` and `git status` commands to make sure nothing weird was present.
 Also I used `-m` to illustrate, but you should compose a proper message in an editor (using a commit message template).
 
 It is also important to create an annotated tag, otherwise the push will be rejected.
 Only annotated tags are allowed to be pushed.
 The annotated tag gives you a chance to enter a commit message.
 Enter the version you are importing, along with any salient new features or fixes in that version.
 
 ==== Updating the FreeBSD Copy
 
 At this point you can push the import to vendor into our repo.
 
 [source,shell]
 ....
 % git push --follow-tags freebsd vendor/NetBSD/mtree
 ....
 
 `--follow-tags` tells `git push` to also push tags associated with the locally committed revision.
 
 ==== Updating the FreeBSD source tree
 
 Now you need to update the mtree in FreeBSD.
 The sources live in `contrib/mtree` since it is upstream software.
 
 [source,shell]
 ....
 % cd ../src
 % git subtree merge -P contrib/mtree vendor/NetBSD/mtree
 ....
 
 This would generate a subtree merge commit of `contrib/mtree` against the local `vendor/NetBSD/mtree` branch.
 If there were conflicts, you would need to fix them before committing.
 Include details about the changes being merged in the merge commit message.
 
 ==== Rebasing your change against latest FreeBSD source tree
 
 Because the current policy recommends against using merges, if the upstream FreeBSD `main` moved forward before you get a chance to push, you would have to redo the merge.
 
 Regular `git rebase` or `git pull --rebase` doesn't know how to rebase a merge commit **as a merge commit**,
 so instead of that you would have to recreate the commit.
 
 The easiest way to do this would be to create a side branch with the **contents** of the merged tree:
 
 [source,shell]
 ....
 % cd ../src
 % git fetch freebsd
 % git checkout -b merge_result
 % git merge freebsd/main
 ....
 
 Typically, there would be no merge conflicts here (because developers tend to work on different components).
 In the worst case scenario, you would still have to resolve merge conflicts, if there was any, but this  should be really rare.
 
 Now, checkout `freebsd/main` again as `new_merge`, and redo the merge:
 
 [source,shell]
 ....
 % git checkout -b new_merge freebsd/main
 % git subtree merge -P contrib/mtree vendor/NetBSD/mtree
 ....
 
 Instead of resolving the conflicts, perform this instead:
 
 [source,shell]
 ....
 % git checkout merge_result .
 ....
 
 Which will overwrite the files with conflicts with the version found in `merge_result`.
 
 Examine the tree against `merge_result` to make sure that you haven't missed deleted files:
 
 [source,shell]
 ....
 % git diff merge_result
 ....
 
 ==== Pushing the changes
 
 Once you are sure that you have a set of deltas you think is good, you can push it to a fork off GitHub or GitLab for others to review.
 One nice thing about Git is that it allows you to publish rough drafts of your work for others to review.
 While phabricator is good for content review, publishing the updated vendor branch and merge commits lets others check the details as they will eventually appear in the repository.
 
 After review, when you are sure it is a good change, you can push it to the FreeBSD repo:
 
 [source,shell]
 ....
 % git push freebsd main
 ....
 
 === Creating a new vendor branch
 
 There are a number of ways to create a new vendor branch.
 The recommended way is to create a new repository and then merge that with FreeBSD.
 If one is importing `glorbnitz` into the FreeBSD tree, release 3.1415.
 For the sake of simplicity, we will not trim this release.
 It is a simple user command that puts the nitz device into different magical glorb states and is small enough trimming will not save much.
 
 ==== Create the repo
 
 [source,shell]
 ....
 % cd /some/where
 % mkdir glorbnitz
 % cd glorbnitz
 % git init
 % git checkout -b vendor/glorbnitz
 ....
 
 At this point, you have a new repo, where all new commits will go on the `vendor/glorbnitz` branch.
 
 Git experts can also do this right in their FreeBSD clone, using `git checkout --orphan vendor/glorbnitz` if they are more comfortable with that.
 
 ==== Copy the sources in
 
 Since this is a new import, you can just cp the sources in, or use tar or even rsync as shown above.
 And we will add everything, assuming no dot files.
 
 [source,shell]
 ....
 % cp -r ~/glorbnitz/* .
 % git add *
 ....
 
 At this point, you should have a pristine copy of glorbnitz ready to commit.
 
 [source,shell]
 ....
 % git commit -m"Import GlorbNitz frobnosticator revision 3.1415"
 ....
 
 As above, I used `-m` for simplicity, but you should likely create a commit message that explains what a Glorb is and why you'd use a Nitz to get it.
 Not everybody will know.
 But for your actual commit, you should follow the <<commit-log-message,commit log message>> section instead of emulating the brief style used here.
 
 ==== Now import it into our repository
 
 Now you need to import the branch into our repository.
 
 [source,shell]
 ....
 % cd /path/to/freebsd/repo/src
 % git remote add glorbnitz /some/where/glorbnitz
 % git fetch glorbnitz vendor/glorbnitz
 ....
 
 Note the vendor/glorbnitz branch is in the repo. At this point the `/some/where/glorbnitz` can be deleted, if you like.
 It was only a means to an end.
 
 ==== Tag and push
 
 Steps from here on out are much the same as they are in the case of updating a vendor branch, though without the updating the vendor branch step.
 
 [source,shell]
 ....
 % git worktree add ../glorbnitz vendor/glorbnitz
 % cd ../glorbnitz
 % git tag --annotate vendor/glorbnitz/3.1415
 # Make sure the commit is good with "git show"
 % git push --follow-tags freebsd vendor/glorbnitz
 ....
 
 By 'good' we mean:
 
 . All the right files are present
 . None of the wrong files are present
 . The vendor branch points at something sensible
 . The tag looks good, and is annotated
 . The commit message for the tag has a quick summary of what's new since the last tag
 
 ==== Time to finally merge it into the base tree
 
 [source,shell]
 ....
 % cd ../src
 % git subtree add -P contrib/glorbnitz vendor/glorbnitz
 # Make sure the commit is good with "git show"
 % git commit --amend   # one last sanity check on commit message
 % git push freebsd
 ....
 
 Here 'good' means:
 
 . All the right files, and none of the wrong ones, were merged into contrib/glorbnitz.
 . No other changes are in the tree.
 . The commit messages look <<commit-log-message,good>>. It should contain a summary of what's changed since the last merge to the FreeBSD main line and any caveats.
 . UPDATING should be updated if there is anything of note, such as user visible changes, important upgrade concerns, etc.
 
 [NOTE]
 ====
 This hasn't connected `glorbnitz` to the build yet.
 How so do that is specific to the software being imported and is beyond the scope of this tutorial.
 ====
 
 === FreeBSD Src Committer Transition Guide
 
 This section is designed to walk people through the conversion process from Subversion to Git, written from the source committer's point of view.
 
 ==== Migrating from a Subversion tree
 
 This section will cover a couple of common scenarios for migrating from using the FreeBSD Subversion repo to the FreeBSD source Git repo.
 The FreeBSD Git conversion is still in beta status, so some minor things may change between this and going into production.
 
 The first thing to do is install Git. Any version of Git will do, though the latest one in ports / packages generally will be good.
 Either build it from ports, or install it using pkg (though some folks might use `su` or `doas` instead of `sudo`):
 
 [source,shell]
 ....
 % sudo pkg install git
 ....
 
 ===== No staged changes migration
 
 If you have no changes pending, the migration is straightforward.
 In this, you abandon the Subversion tree and clone the Git repository.
 It's likely best to retain your Subversion tree, in case there's something you've forgotten about there.
 First, let's clone the repository:
 
 [source,shell]
 ....
 % git clone -o freebsd --config remote.freebsd.fetch='+refs/notes/*:refs/notes/*' https://git.freebsd.org/src.git freebsd-src
 ....
 
 will create a clone of the FreeBSD src repository into a subdirectory called `freebsd-src` and include the 'notes' about the revisions.
 We are currently mirroring the source repository to https://github.com/freebsd/freebsd-src.git as well.
 https://github.com/freebsd/freebsd-legacy.git has the old GitHub mirror with the old hashes should you need that for your migration.
 The GitHub `master` branch has been frozen.
 As the default in Git has changed, we've shifted from `master` to `main`; the new repository uses `main`.
 We also mirror the repository to GitLab at https://gitlab.com/FreeBSD/src.git .
 
 It's useful to have the old Subversion revisions available.
 This data is stored using Git notes, but Git doesn't fetch those by default.
 The --config and the argument above changed the default to fetch the notes.
 If you've cloned the repository without this, or wish to add notes to a previously cloned repository, use the following commands:
 
 [source,shell]
 ....
 % git config --add remote.freebsd.fetch "+refs/notes/*:refs/notes/*"
 % git fetch
 ....
 
 At this point you have the src checked out into a Git tree, ready to do other things.
 
 ===== But I have changes that I've not committed
 
 If you are migrating from a tree that has changes you've not yet committed to FreeBSD, you'll need to follow the steps from the previous section first, and then follow these.
 
 [source,shell]
 ....
 % cd path-to-svn-checkout-tree
 % svn diff > /tmp/src.diff
 % cd _mumble_/freebsd-src
 % git checkout -b working
 ....
 
 This will create a diff of your current changes.
 The last command creates a branch called `working` though you can call it whatever you want.
 
 [source,shell]
 ....
 % git apply /tmp/src.diff
 ....
 
 this will apply all your pending changes to the working tree.
 This doesn't commit the change, so you'll need to make this permanent:
 
 [source,shell]
 ....
 % git add _files_
 % git commit
 ....
 
 The last command will commit these changes to the branch.
 The editor will prompt you for a commit message.
 Enter one as if you were committing to FreeBSD.
 
 At this point, your work is preserved, and in the Git repository.
 
 ===== Keeping current
 
 So, time passes.
 It's time now to update the tree for the latest changes upstream.
 When you checkout `main` make sure that you have no diffs.
 It's a lot easier to commit those to a branch (or use `git stash`) before doing the following.
 
 If you are used to `git pull`, we strongly recommend using the `--ff-only` option, and further setting it as the default option.
 Alternatively, `git pull --rebase` is useful if you have changes staged in the main branch.
 
 [source,shell]
 ....
 % git config --global pull.ff only
 ....
 
 You may need to omit the --global if you want this setting to apply to only this repository.
 
 [source,shell]
 ....
 % cd freebsd-src
 % git checkout main
 % git pull (--ff-only|--rebase)
 ....
 
 There is a common trap, that the combination command `git pull` will try to perform a merge, which would sometimes creates a merge commit that didn't exist before.
 This can be harder to recover from.
 
 The longer form is also recommended.
 
 [source,shell]
 ....
 % cd freebsd-src
 % git checkout main
 % git fetch freebsd
 % git merge --ff-only freebsd/main
 ....
 
 These commands reset your tree to the main branch, and then update it from where you pulled the tree from originally.
 It's important to switch to `main` before doing this so it moves forward.
 Now, it's time to move the changes forward:
 
 [source,shell]
 ....
 % git rebase -i main working
 ....
 
 This will bring up an interactive screen to change the defaults.
 For now, just exit the editor.
 Everything should just apply.
 If not, then you'll need to resolve the diffs.
 https://docs.github.com/en/free-pro-team@latest/github/using-git/resolving-merge-conflicts-after-a-git-rebase[This github document] can help you navigate this process.
 
 ===== Time to push changes upstream
 
 First, ensure that the push URL is properly configured for the upstream repository.
 
 [source,shell]
 ....
 % git remote set-url --push freebsd ssh://git@gitrepo.freebsd.org/src.git
 ....
 
 Then, verify that user name and email are configured right.
 We require that they exactly match the passwd entry in FreeBSD cluster.
 
 Use
 
 [source,shell]
 ....
 freefall% gen-gitconfig.sh
 ....
 
 on freefall.freebsd.org to get a recipe that you can use directly, assuming /usr/local/bin is in the PATH.
 
 The below command merges the 'working' branch into the upstream main line.
 It's important that you curate your changes to be just like you want them in the FreeBSD source repo before doing this.
 
 [source,shell]
 ....
 % git push freebsd working:main
 ....
 
 If your push is rejected due to losing a commit race, rebase your branch before trying again:
 
 [source,shell]
 ....
 % git checkout working
 % git fetch freebsd
 % git rebase freebsd/main
 % git push freebsd working:main
 ....
 
 ===== Finding the Subversion Revision
 
 You'll need to make sure that you've fetched the notes (see the `No staged changes migration` section above for details.
 Once you have these, notes will show up in the git log command like so:
 
 [source,shell]
 ....
 % git log
 ....
 
 If you have a specific version in mind, you can use this construct:
 
 [source,shell]
 ....
 % git log --grep revision=XXXX
 ....
 
 to find the specific revision.
 The hex number after 'commit' is the hash you can use to refer to this commit.
 
 ==== Migrating from GitHub fork
 
 Note: as of this writing, https://github.com/freebsd/freebsd-src is mirroring all official branches, along with a `master` branch which is the legacy svn2git result.
 The `master` branch will not be updated anymore, and the link:https://github.com/freebsd/freebsd-src/commit/de1aa3dab23c06fec962a14da3e7b4755c5880cf[last commit] contains the instructions for migrating to the new `main` branch.
 We'll retain the `master` branch for a certain time, but in the future it will only be kept in the link:https://github.com/freebsd/freebsd-legacy[freebsd-legacy] repository.
 
 When migrating branches from a GitHub fork from the old GitHub mirror to the official repo, the process is straight forward.
 This assumes that you have a `freebsd` upstream pointing to GitHub, adjust if necessary.
 This also assumes a clean tree before starting...
 
 ===== Add the new `freebsd` upstream repository:
 
 [source,shell]
 ....
 % git remote add freebsd https://git.freebsd.org/src.git
 % git fetch freebsd
 % git checkout --track freebsd/main
 ....
 
 ===== Rebase all your WIP branches.
 
 For each branch FOO, do the following after fetching the `freebsd` sources and creating a local `main` branch with the above checkout:
 
 [source,shell]
 ....
 % git rebase -i freebsd/master FOO --onto main
 ....
 
 And you'll now be tracking the official repository.
 You can then follow the `Keeping Current` section above to stay up to date.
 
 If you need to then commit work to FreeBSD, you can do so following the `Time to push changes upstream` instructions.
 You'll need to do the following once to update the push URL if you are a FreeBSD committer:
 
 [source,shell]
 ....
 % git remote set-url --push freebsd ssh://git@gitrepo.freebsd.org/src.git
 ....
 
 (note that gitrepo.freebsd.org will be change to repo.freebsd.org in the future.)
 
 You will also need to add `freebsd` as the location to push to.
 The author recommends that your upstream GitHub repository remain the default push location so that you only push things into FreeBSD you intend to by making it explicit.
 
 [[git-faq]]
 === Git FAQ
 
 This section  provides a number of targeted answers to questions that are likely to come up often for users and developers.
 
 [NOTE]
 ====
 We use the common convention of having the origin for the FreeBSD repository being 'freebsd' rather than the default 'origin' to allow
 people to use that for their own development and to minimize "whoopse" pushes to the wrong repository.
 ====
 
 ==== Users
 
 ===== How do I track -current and -stable with only one copy of the repository?
 
 **Q:** Although disk space is not a huge issue, it's more efficient to use only one copy of the repository.
 With SVN mirroring, I could checkout multiple trees from the same repository.
 How do I do this with Git?
 
 **A:** You can use Git worktrees.
 There's a number of ways to do this, but the simplest way is to use a clone to track -current, and a worktree to track stable releases.
 While using a 'bare repository' has been put forward as a way to cope, it's more complicated and will not be documented here.
 
 First, you need to clone the FreeBSD repository, shown here cloning into `freebsd-current` to reduce confusion.
 $URL is whatever mirror works best for you:
 
 [source,shell]
 ....
 % git clone -o freebsd --config remote.freebsd.fetch='+refs/notes/*:refs/notes/*' $URL freebsd-current
 ....
 
 then once that's cloned, you can simply create a worktree from it:
 
 [source,shell]
 ....
 % cd freebsd-current
 % git worktree add ../freebsd-stable-12 stable/12
 ....
 
 this will checkout `stable/12` into a directory named `freebsd-stable-12` that's a peer to the `freebsd-current` directory.
 Once created, it's updated very similarly to how you might expect:
 
 [source,shell]
 ....
 % cd freebsd-current
 % git checkout main
 % git pull --ff-only
 # changes from upstream now local and current tree updated
 % cd ../freebsd-stable-12
 % git merge --ff-only freebsd/stable/12
 # now your stable/12 is up to date too
 ....
 
 I recommend using `--ff-only` because it's safer and you avoid accidentally getting into a 'merge nightmare' where you have an extra change in your tree, forcing a complicated merge rather than a simple one.
 
 Here's https://adventurist.me/posts/00296[a good writeup] that goes into more detail.
 
 ==== Developers
 
 ===== Ooops! I committed to `main` instead of a branch.
 
 **Q:** From time to time, I goof up and commit to main instead of to a branch. What do I do?
 
 **A:** First, don't panic.
 
 Second, don't push.
 In fact, you can fix almost anything if you haven't pushed.
 All the answers in this section assume no push has happened.
 
 The following answer assumes you committed to `main` and want to create a branch called `issue`:
 
 [source,shell]
 ....
 % git branch issue                # Create the 'issue' branch
 % git reset --hard freebsd/main   # Reset 'main' back to the official tip
 % git checkout issue              # Back to where you were
 ....
 
 ===== Ooops! I committed something to the wrong branch!
 
 **Q:** I was working on feature on the `wilma` branch, but accidentally committed a change relevant to the `fred` branch in 'wilma'.
 What do I do?
 
 **A:** The answer is similar to the previous one, but with cherry picking.
 This assumes there's only one commit on wilma, but will generalize to more complicated situations.
 It also assumes that it's the last commit on wilma (hence using wilma in the `git cherry-pick` command), but that too can be generalized.
 
 [source,shell]
 ....
 # We're on branch wilma
 % git checkout fred		# move to fred branch
 % git cherry-pick wilma		# copy the misplaced commit
 % git checkout wilma		# go back to wilma branch
 % git reset --hard HEAD^	# move what wilma refers to back 1 commit
 ....
 
 Git experts would first rewind the wilma branch by 1 commit, switch over to fred and then use `git reflog` to see what that 1 deleted commit was and
 cherry-pick it over.
 
 **Q:** But what if I want to commit a few changes to `main`, but keep the rest in `wilma` for some reason?
 
 **A:** The same technique above also works if you are wanting to 'land' parts of the branch you are working on into `main` before the rest of the branch is ready (say you noticed an unrelated typo, or fixed an incidental bug).
 You can cherry pick those changes into main, then push to the parent repository.
 Once you've done that, cleanup couldn't be simpler: just `git rebase -i`.
 Git will notice you've done this and skip the common changes automatically (even if you had to change the commit message or tweak the commit slightly).
 There's no need to switch back to wilma to adjust it: just rebase!
 
 **Q:** I want to split off some changes from branch `wilma` into branch `fred`
 
 **A:** The more general answer would be the same as the previous.
 You'd checkout/create the `fred` branch, cherry pick the changes you want from `wilma` one at a time, then rebase `wilma` to remove those changes you cherry picked.
 `git rebase -i main wilma` will toss you into an editor, and remove the `pick` lines that correspond to the commits you copied to `fred`.
 If all goes well, and there are no conflicts, you're done.
 If not, you'll need to resolve the conflicts as you go.
 
 The other way to do this would be to checkout `wilma` and then create the branch `fred` to point to the same point in the tree.
 You can then `git rebase -i` both these branches, selecting the changes you want in `fred` or `wilma` by retaining the pick likes, and deleting the rest from the editor.
 Some people would create a tag/branch called `pre-split` before starting in case something goes wrong in the split.
 You can undo it with the following sequence:
 
 [source,shell]
 ....
 % git checkout pre-split	# Go back
 % git branch -D fred		# delete the fred branch
 % git checkout -B wilma		# reset the wilma branch
 % git branch -d pre-split	# Pretend it didn't happen
 ....
 
 The last step is optional.
 If you are going to try again to split, you'd omit it.
 
 **Q:** But I did things as I read along and didn't see your advice at the end to create a branch, and now `fred` and `wilma` are all screwed up.
 How do I find what `wilma` was before I started.
 I don't know how many times I moved things around.
 
 **A:** All is not lost. You can figure out it, so long as it hasn't been too long, or too many commits (hundreds).
 
 So I created a wilma branch and committed a couple of things to it, then decided I wanted to split it into fred and wilma.
 Nothing weird happened when I did that, but let's say it did.
 The way to look at what you've done is with the `git reflog`:
 
 [source,shell]
 ....
 % git reflog
 6ff9c25 (HEAD -> wilma) HEAD@{0}: rebase -i (finish): returning to refs/heads/wilma
 6ff9c25 (HEAD -> wilma) HEAD@{1}: rebase -i (start): checkout main
 869cbd3 HEAD@{2}: rebase -i (start): checkout wilma
 a6a5094 (fred) HEAD@{3}: rebase -i (finish): returning to refs/heads/fred
 a6a5094 (fred) HEAD@{4}: rebase -i (pick): Encourage contributions
 1ccd109 (freebsd/main, main) HEAD@{5}: rebase -i (start): checkout main
 869cbd3 HEAD@{6}: rebase -i (start): checkout fred
 869cbd3 HEAD@{7}: checkout: moving from wilma to fred
 869cbd3 HEAD@{8}: commit: Encourage contributions
 ...
 %
 ....
 
 Here we see the changes I've made.
 You can use it to figure out where things went wrong.
 I'll just point out a few things here.
 The first one is that HEAD@{X} is a 'commitish' thing, so you can use that as an argument to a command.
 Although if that command commits anything to the repository, the X numbers change.
 You can also use the hash (first column).
 
 Next, 'Encourage contributions' was the last commit I made to `wilma` before I decided to split things up.
 You can also see the same hash is there when I created the `fred` branch to do that.
 I started by rebasing `fred` and you see the 'start', each step, and the 'finish' for that process.
 While we don't need it here, you can figure out exactly what happened.
 Fortunately, to fix this, you can follow the prior answer's steps, but with the hash `869cbd3` instead of `pre-split`.
 While that seems a bit verbose, it's easy to remember since you're doing one thing at a time.
 You can also stack:
 
 [source,shell]
 ....
 % git checkout -B wilma 869cbd3
 % git branch -D fred
 ....
 
 and you are ready to try again.
 The 'checkout -B' with the hash combines checking out and creating a branch for it.
 The -B instead of -b forces the movement of a pre-existing branch.
 Either way works, which is what's great (and awful) about Git.
 One reason I tend to use `git checkout -B xxxx hash` instead of checking out the hash, and then creating / moving the branch is purely to avoid the slightly distressing message about detached heads:
 
 [source,shell]
 ....
 % git checkout 869cbd3
 M	faq.md
 Note: checking out '869cbd3'.
 
 You are in 'detached HEAD' state. You can look around, make experimental
 changes and commit them, and you can discard any commits you make in this
 state without impacting any branches by performing another checkout.
 
 If you want to create a new branch to retain commits you create, you may
 do so (now or later) by using -b with the checkout command again. Example:
 
   git checkout -b <new-branch-name>
 
 HEAD is now at 869cbd3 Encourage contributions
 % git checkout -B wilma
 ....
 
 this produces the same effect, but I have to read a lot more and severed heads aren't an image I like to contemplate.
 
 ===== Ooops! I did a `git pull` and it created a merge commit, what do I do?
 
 **Q:** I was on autopilot and did a `git pull` for my development tree and that created a merge commit on the mainline.
 How do I recover?
 
 **A:** This can happen when you invoke the pull with your development branch checked out.
 
 Right after the pull, you will have the new merge commit checked out.
 Git supports a `HEAD^#` syntax to examine the parents of a merge commit:
 
 [source,shell]
 ....
 git log --oneline HEAD^1   # Look at the first parent's commits
 git log --oneline HEAD^2   # Look at the second parent's commits
 ....
 
 From those logs, you can easily identify which commit is your development work.
 Then you simply reset your branch to the corresponding `HEAD^#`:
 
 [source,shell]
 ....
 git reset --hard HEAD^2
 ....
 
 **Q:** But I also need to fix my `main` branch. How do I do that?
 
 **A:** Git keeps track of the remote repository branches in a `freebsd/` namespace.
 To fix your `main` branch, just make it point to the remote's `main`:
 
 [source,shell]
 ....
 git branch -f main freebsd/main
 ....
 
 There's nothing magical about branches in Git: they are just labels on a graph that are automatically moved forward by making commits.
 So the above works because you're just moving a label.
 There's no metadata about the branch that needs to be preserved due to this.
 
 ===== Mixing and matching branches
 
 **Q:** So I have two branches `worker` and `async` that I'd like to combine into one branch called `feature`
 while maintaining the commits in both.
 
 **A:** This is a job for cherry pick.
 
 [source,shell]
 ....
 % git checkout worker
 % git checkout -b feature	# create a new branch
 % git cherry-pick main..async	# bring in the changes
 ....
 
 You now have a new branch called `feature`.
 This branch combines commits from both branches.
 You can further curate it with `git rebase`.
 
 **Q:** I have a branch called `driver` and I'd like to break it up into `kernel` and `userland` so I can evolve them separately and commit each branch as it becomes ready.
 
 **A:** This takes a little bit of prep work, but `git rebase` will do the heavy
 lifting here.
 
 [source,shell]
 ....
 % git checkout driver		# Checkout the driver
 % git checkout -b kernel	# Create kernel branch
 % git checkout -b userland	# Create userland branch
 ....
 
 Now you have two identical branches.
 So, it's time to separate out the commits.
 We'll assume first that all the commits in `driver` go into either the `kernel` or the `userland` branch, but not both.
 
 [source,shell]
 ....
 % git rebase -i main kernel
 ....
 
 and just include the changes you want (with a 'p' or 'pick' line) and just delete the commits you don't (this sounds scary, but if worse comes to worse, you can throw this all away and start over with the `driver` branch since you've not yet moved it).
 
 [source,shell]
 ....
 % git rebase -i main userland
 ....
 
 and do the same thing you did with the `kernel` branch.
 
 **Q:** Oh great! I followed the above and forgot a commit in the `kernel` branch.
 How do I recover?
 
 **A:** You can use the `driver` branch to find the hash of the commit is missing and
 cherry pick it.
 
 [source,shell]
 ....
 % git checkout kernel
 % git log driver
 % git cherry-pick $HASH
 ....
 
 **Q:** OK. I have the same situation as the above, but my commits are all mixed up.
 I need parts of one commit to go to one branch and the rest to go to the other.
 In fact, I have several.
 Your rebase method to select sounds tricky.
 
 **A:** In this situation, you'd be better off to curate the original branch to separate
 out the commits, and then use the above method to split the branch.
 
 So let's assume that there's just one commit with a clean tree.
 You can either use `git rebase` with an `edit` line, or you can use this with the commit on the tip.
 The steps are the same either way.
 The first thing we need to do is to back up one commit while leaving the changes uncommitted in the tree:
 
 [source,shell]
 ....
 % git reset HEAD^
 ....
 
 Note: Do not, repeat do not, add `--hard` here since that also removes the changes from your tree.
 
 Now, if you are lucky, the change needing to be split up falls entirely along file lines.
 In that case you can just do the usual `git add` for the files in each group than do a `git commit`.
 Note: when you do this, you'll lose the commit message when you do the reset, so if you need it for some reason, you should save a copy (though `git log $HASH` can recover it).
 
 If you are not lucky, you'll need to split apart files.
 There's another tool to do that which you can apply one file at a time.
 
 [source,shell]
 ....
 git add -i foo/bar.c
 ....
 
 will step through the diffs, prompting you, one at time, whether to include or exclude the hunk.
 Once you're done, `git commit` and you'll have the remainder in your tree.
 You can run it multiple times as well, and even over multiple files (though I find it easier to do one file at a time
 and use the `git rebase -i` to fold the related commits together).
 
 ==== Cloning and Mirroring
 
 **Q:** I'd like to mirror the entire Git repository, how do I do that?
 
 **A:** If all you want to do is mirror, then
 
 [source,shell]
 ....
 % git clone --mirror $URL
 ....
 
 will do the trick.
 However, there are two disadvantages to this if you want to use it for anything other than a mirror you'll reclone.
 
 First, this is a 'bare repository' which has the repository database, but no checked out worktree.
 This is great for mirroring, but terrible for day to day work.
 There's a number of ways around this with 'git worktree':
 
 [source,shell]
 ....
 % git clone --mirror https://git.freebsd.org/ports.git ports.git
 % cd ports.git
 % git worktree add ../ports main
 % git worktree add ../quarterly branches/2020Q4
 % cd ../ports
 ....
 
 But if you aren't using your mirror for further local clones, then it's a poor match.
 
 The second disadvantage is that Git normally rewrites the refs (branch name, tags, etc) from upstream so that your local refs can evolve independently of upstream.
 This means that you'll lose changes if you are committing to this repository on anything other than private project branches.
 
 **Q:** So what can I do instead?
 
 **A:** Well, you can stuff all of the upstream repository's refs into a private namespace in your local repository.
 Git clones everything via a 'refspec' and the default refspec is:
 
 [source,shell]
 ....
         fetch = +refs/heads/*:refs/remotes/freebsd/*
 ....
 
 which says just fetch the branch refs.
 
 However, the FreeBSD repository has a number of other things in it.
 To see those, you can add explicit refspecs for each ref namespace, or you can fetch everything.
 To setup your repository to do that:
 
 [source,shell]
 ....
 git config --add remote.freebsd.fetch '+refs/*:refs/freebsd/*'
 ....
 
 which will put everything in the upstream repository into your local repository's 'refs/freebsd/' namespace.
 Please note, that this also grabs all the unconverted vendor branches and the number of refs associated with them is quite large.
 
 You'll need to refer to these 'refs' with their full name because they aren't in and of Git's regular namespaces.
 
 [source,shell]
 ....
 git log refs/freebsd/vendor/zlib/1.2.10
 ....
 
 would look at the log for the vendor branch for zlib starting at 1.2.10.
 
 === Collaborating with others
 
 One of the keys to good software development on a project as large as FreeBSD is the ability to collaborate with others before you push your changes to the tree.
 The FreeBSD project's Git repositories do not, yet, allow user-created branches to be pushed to the repository, and therefore if you wish to share your changes with others you must use another mechanism, such as a hosted GitLab or GitHub, in order to share changes in a user-generated branch.
 
 The following instructions show how to set up a user-generated branch, based on the FreeBSD main branch, and push it to GitHub.
 
 Before you begin, make sure that your local Git repo is up to date and has the correct origins set <<keeping_current,as shown above.>>
 
 [source,shell]
 ````
 % git remote -v
 freebsd https://git.freebsd.org/src.git (fetch)
 freebsd ssh://git@gitrepo.freebsd.org/src.git (push)
 ````
 
 The first step is to create a fork of https://github.com/freebsd/freebsd-src[FreeBSD] on GitHub following these https://docs.github.com/en/github/getting-started-with-github/fork-a-repo[guidelines].
 The destination of the fork should be your own, personal, GitHub account (gvnn3 in my case).
 
 Now add a remote on your local system that points to your fork:
 [source,shell]
 ....
 % git remote add github git@github.com:gvnn3/freebsd-src.git
 % git remote -v
 github	git@github.com:gvnn3/freebsd-src.git (fetch)
 github	git@github.com:gvnn3/freebsd-src.git (push)
 freebsd	https://git.freebsd.org/src.git (fetch)
 freebsd	ssh://git@gitrepo.freebsd.org/src.git (push)
 ....
 With this in place you can create a branch <<keeping_a_local_branch,as shown above.>>
 
 [source,shell]
 ....
 % git checkout -b gnn-pr2001-fix
 ....
 
 Make whatever modifications you wish in your branch.  Build, test, and once you're ready to collaborate with others it's time to push your changes into your hosted branch.
 Before you can push you'll have to set the appropriate upstream, as Git will tell you the first time you try to push to your +github+ remote:
 
 [source,shell]
 ....
 % git push github
 fatal: The current branch gnn-pr2001-fix has no upstream branch.
 To push the current branch and set the remote as upstream, use
 
     git push --set-upstream github gnn-pr2001-fix
 ....
 
 Setting the push as +git+ advises allows it to succeed:
 
 [source,shell]
 ....
 % git push --set-upstream github gnn-feature
 Enumerating objects: 20486, done.
 Counting objects: 100% (20486/20486), done.
 Delta compression using up to 8 threads
 Compressing objects: 100% (12202/12202), done.
 Writing objects: 100% (20180/20180), 56.25 MiB | 13.15 MiB/s, done.
 Total 20180 (delta 11316), reused 12972 (delta 7770), pack-reused 0
 remote: Resolving deltas: 100% (11316/11316), completed with 247 local objects.
 remote:
 remote: Create a pull request for 'gnn-feature' on GitHub by visiting:
 remote:      https://github.com/gvnn3/freebsd-src/pull/new/gnn-feature
 remote:
 To github.com:gvnn3/freebsd-src.git
  * [new branch]                gnn-feature -> gnn-feature
 Branch 'gnn-feature' set up to track remote branch 'gnn-feature' from 'github'.
 ....
 
 Subsequent changes to the same branch will push correctly by default:
 
 [source,shell]
 ....
 % git push
 Enumerating objects: 4, done.
 Counting objects: 100% (4/4), done.
 Delta compression using up to 8 threads
 Compressing objects: 100% (2/2), done.
 Writing objects: 100% (3/3), 314 bytes | 1024 bytes/s, done.
 Total 3 (delta 1), reused 1 (delta 0), pack-reused 0
 remote: Resolving deltas: 100% (1/1), completed with 1 local object.
 To github.com:gvnn3/freebsd-src.git
    9e5243d7b659..cf6aeb8d7dda  gnn-feature -> gnn-feature
 ....
 
 At this point your work is now in your branch on +GitHub+ and you can
 share the link with other collaborators.
 
 === Landing a github pull request
 This section documents how to land a GitHub pull request that's submitted against the FreeBSD Git mirrors at GitHub.
 While this is not an official way to submit patches at this time, sometimes good fixes come in this way and it is easiest just to bring them into a committer's tree and have them pushed into the FreeBSD's tree from there.
 Similar steps can be used to pull branches from other repositories and land those.
 When committing pull requests from others, one should take extra care to examine all the changes to ensure they are exactly as represented.
 
 Before beginning, make sure that the local Git repo is up to date and has the correct origins set <<keeping_current,as shown above.>>
 In addition, make sure to have the following origins:
 [source,shell]
 ....
 % git remote -v
 freebsd https://git.freebsd.org/src.git (fetch)
 freebsd ssh://git@gitrepo.freebsd.org/src.git (push)
 github https://github.com/freebsd/freebsd-src (fetch)
 github https://github.com/freebsd/freebsd-src (fetch)
 ....
 Often pull requests are simple: requests that contain only a single commit.
 In this case, a streamlined approach may be used, though the approach in the prior section will also work.
 Here, a branch is created, the change is cherry picked, the commit message adjusted, and sanity-checked before being pushed.
 The branch `staging` is used in this example but it can be any name.
 This technique works for any number of commits in the pull request, especailly when the changes apply cleanly to the FreeBSD tree.
 However, when there's multiple commits, especially when minor adjustments are needed, `git rebase -i` works better than `git cherry-pick`.
 Briefly, these commands create a branch; cherry-picks the changes from the pull request; tests it; adjusts the commit messages; and fast forward merges it back to `main`.
 The PR number is `$PR` below.
 When adjusting the message, add `Pull Request: https://github.com/freebsd-src/pull/$PR`.
 [source,shell]
 ....
 % git fetch github pull/$PR/head:staging
 % git rebase -i main staging	# to move the staging branch forward, adjust commit message here
 <do testing here, as needed>
 % git checkout main
 % git pull --ff-only		# to get the latest if time has passed
 % git checkout main
 % git merge --ff-only staging
 <test again if needed>
 % git push freebsd --push-option=confirm-author
 ....
 
 [.procedure]
 ====
 For complicated pull requests that have multiple commits with conflicts, follow the following outline.
 
 . checkout the pull request `git checkout github/pull/XXX`
 . create a branch to rebase `git checkout -b staging`
 . rebase the `staging` branch to the latest `main` with `git rebase -i main staging`
 . resolve conflicts and do whatever testing is needed
 . fast forward the `staging` branch into `main` as above
 . final sanity check of changes to make sure all is well
 . push to FreeBSD's Git repository.
 
 This will also work when bringing branches developed elsewhere into the local tree for committing.
 ====
 Once finished with the pull request, close it using GitHub's web interface.
 It is worth noting that if your `github` origin uses `https://`, the only step you'll need a GitHub account for is closing the pull request.
 
 [[vcs-history]]
 == Version Control History
 
 The project has moved to <<git-primer,git>>.
 
 The FreeBSD source repository switched from CVS to Subversion on May 31st, 2008.
 The first real SVN commit is __r179447__.
 The source repository switched from Subversion to Git on December 23rd, 2020.
 The last real svn commit is __r368820__.
 The first real git commit hash is __5ef5f51d2bef80b0ede9b10ad5b0e9440b60518c__
 
 The FreeBSD `doc/www` repository switched from CVS to Subversion on May 19th, 2012.
 The first real SVN commit is __r38821__.
 The documentation repository switched from Subversion to Git on December 8th, 2020.
 The last SVN commit is __r54737__.
 The first real git commit hash is __3be01a475855e7511ad755b2defd2e0da5d58bbe__.
 
 The FreeBSD `ports` repository switched from CVS to Subversion on July 14th, 2012.
 The first real SVN commit is __r300894__.
 The ports repository switched from Subversion to Git on April 6, 2021.
 The last SVN commit is __r569609__
 The first real git commit hash is __ed8d3eda309dd863fb66e04bccaa513eee255cbf__.
 
 [[conventions]]
 == Setup, Conventions, and Traditions
 
 There are a number of things to do as a new developer.
 The first set of steps is specific to committers only.
 These steps must be done by a mentor for those who are not committers.
 
 [[conventions-committers]]
 === For New Committers
 
 Those who have been given commit rights to the FreeBSD repositories must follow these steps.
 
 * Get mentor approval before committing each of these changes!
 * All [.filename]#src# commits go to FreeBSD-CURRENT first before being merged to FreeBSD-STABLE. The FreeBSD-STABLE branch must maintain ABI and API compatibility with earlier versions of that branch. Do not merge changes that break this compatibility.
 
 [[commit-steps]]
 [.procedure]
 ====
 *Procedure 1. Steps for New Committers*
 
 . Add an Author Entity
-+ 
++
 [.filename]#doc/shared/authors.adoc# - Add an author entity. Later steps depend on this entity, and missing this step will cause the [.filename]#doc/# build to fail. This is a relatively easy task, but remains a good first test of version control skills.
 . Update the List of Developers and Contributors
-+ 
++
 [.filename]#doc/documentation/content/en/articles/contributors/contrib-committers.adoc# - Add an entry, which will then appear in the "Developers" section of the link:{contributors}#staff-committers[Contributors List]. Entries are sorted by last name.
-+ 
++
 [.filename]#doc/documentation/content/en/articles/contributors/contrib-additional.adoc# - _Remove_ the entry. Entries are sorted by first name.
 . Add a News Item
-+ 
++
 [.filename]#doc/website/data/en/news/news.toml# - Add an entry. Look for the other entries that announce new committers and follow the format. Use the date from the commit bit approval email from mailto:core@FreeBSD.org[core@FreeBSD.org].
 . Add a PGP Key
-+ 
++
 `{des}` has written a shell script ([.filename]#doc/documentation/tools/addkey.sh#) to make this easier. See the https://cgit.freebsd.org/doc/plain/documentation/static/pgpkeys/README[README] file for more information.
-+ 
++
 Use [.filename]#doc/documentation/tools/checkkey.sh# to verify that keys meet minimal best-practices standards.
-+ 
++
 After adding and checking a key, add both updated files to source control and then commit them. Entries in this file are sorted by last name.
 +
 [NOTE]
 ======
 It is very important to have a current PGP/GnuPG key in the repository. The key may be required for positive identification of a committer. For example, the `{admins}` might need it for account recovery. A complete keyring of `FreeBSD.org` users is available for download from link:https://www.FreeBSD.org/doc/pgpkeyring.txt[https://www.FreeBSD.org/doc/pgpkeyring.txt].
 ======
 . Update Mentor and Mentee Information
-+ 
++
 [.filename]#src/share/misc/committers-<repository>.dot# - Add an entry to the current committers section, where _repository_ is `doc`, `ports`, or `src`, depending on the commit privileges granted.
-+ 
++
 Add an entry for each additional mentor/mentee relationship in the bottom section.
 . Generate a Kerberos Password
-+ 
++
 See <<kerberos-ldap>> to generate or set a Kerberos for use with other FreeBSD services like the bug tracking database.
 . Optional: Enable Wiki Account
-+ 
++
 https://wiki.freebsd.org[FreeBSD Wiki] Account - A wiki account allows sharing projects and ideas. Those who do not yet have an account can follow instructions on the https://wiki.freebsd.org/AboutWiki[AboutWiki Page] to obtain one. Contact mailto:wiki-admin@FreeBSD.org[wiki-admin@FreeBSD.org] if you need help with your Wiki account.
 . Optional: Update Wiki Information
-+ 
++
 Wiki Information - After gaining access to the wiki, some people add entries to the https://wiki.freebsd.org/HowWeGotHere[How We Got Here], https://wiki.freebsd.org/IRC/Nicknames[IRC Nicks], and https://wiki.freebsd.org/Community/Dogs[Dogs of FreeBSD] pages.
 . Optional: Update Ports with Personal Information
-+ 
++
 [.filename]#ports/astro/xearth/files/freebsd.committers.markers# and [.filename]#src/usr.bin/calendar/calendars/calendar.freebsd# - Some people add entries for themselves to these files to show where they are located or the date of their birthday.
 . Optional: Prevent Duplicate Mailings
-+ 
++
 Subscribers to {dev-commits-doc-all}, {dev-commits-ports-all} or {dev-commits-src-all} might wish to unsubscribe to avoid receiving duplicate copies of commit messages and followups.
 ====
 
 [[conventions-everyone]]
 === For Everyone
 
 [[conventions-everyone-steps]]
 [.procedure]
 ====
 . Introduce yourself to the other developers, otherwise no one will have any idea who you are or what you are working on. The introduction need not be a comprehensive biography, just write a paragraph or two about who you are, what you plan to be working on as a developer in FreeBSD, and who will be your mentor. Email this to the {developers-name} and you will be on your way!
 . Log into `freefall.FreeBSD.org` and create a [.filename]#/var/forward/user# (where _user_ is your username) file containing the e-mail address where you want mail addressed to _yourusername_@FreeBSD.org to be forwarded. This includes all of the commit messages as well as any other mail addressed to the {committers-name} and the {developers-name}. Really large mailboxes which have taken up permanent residence on `freefall` may get truncated without warning if space needs to be freed, so forward it or save it elsewhere.
 +
 [NOTE]
 ======
 If your e-mail system uses SPF with strict rules, you should whitelist `mx2.FreeBSD.org` from SPF checks.
 ======
-+ 
++
 Due to the severe load dealing with SPAM places on the central mail servers that do the mailing list processing, the front-end server does do some basic checks and will drop some messages based on these checks. At the moment proper DNS information for the connecting host is the only check in place but that may change. Some people blame these checks for bouncing valid email. To have these checks turned off for your email, create a file named [.filename]#~/.spam_lover# on `freefall.FreeBSD.org`.
 +
 [NOTE]
 ======
 Those who are developers but not committers will not be subscribed to the committers or developers mailing lists. The subscriptions are derived from the access rights.
 ======
 ====
 
 [[smtp-setup]]
 ==== SMTP Access Setup
 
 For those willing to send e-mail messages through the FreeBSD.org infrastructure, follow the instructions below:
 
 [.procedure]
 ====
 . Point your mail client at `smtp.FreeBSD.org:587`.
 . Enable STARTTLS.
 . Ensure your `From:` address is set to `_yourusername_@FreeBSD.org`.
 . For authentication, you can use your FreeBSD Kerberos username and password (see <<kerberos-ldap>>). The `_yourusername_/mail` principal is preferred, as it is only valid for authenticating to mail resources.
 +
 [NOTE]
 ======
 Do not include `@FreeBSD.org` when entering in your username.
 ======
 +
 .Additional Notes
 [NOTE]
 ======
 * Will only accept mail from `_yourusername_@FreeBSD.org`. If you are authenticated as one user, you are not permitted to send mail from another.
 * A header will be appended with the SASL username: (`Authenticated sender: _username_`).
 * Host has various rate limits in place to cut down on brute force attempts.
 ======
 ====
 
 [[smtp-setup-local-mta]]
 ===== Using a Local MTA to Forward Emails to the FreeBSD.org SMTP Service
 
 It is also possible to use a local MTA to forward locally sent emails to the FreeBSD.org SMTP servers.
 
 [[smtp-setup-local-postfix]]
 .Using Postfix
 [example]
 ====
 
 To tell a local Postfix instance that anything from `_yourusername_@FreeBSD.org` should be forwarded to the FreeBSD.org servers, add this to your [.filename]#main.cf#:
 
 [.programlisting]
 ....
 sender_dependent_relayhost_maps = hash:/usr/local/etc/postfix/relayhost_maps
 smtp_sasl_auth_enable = yes
 smtp_sasl_security_options = noanonymous
 smtp_sasl_password_maps = hash:/usr/local/etc/postfix/sasl_passwd
 smtp_use_tls = yes
 ....
 
 Create [.filename]#/usr/local/etc/postfix/relayhost_maps# with the following content:
 
 [.programlisting]
 ....
 yourusername@FreeBSD.org  [smtp.freebsd.org]:587
 ....
 
 Create [.filename]#/usr/local/etc/postfix/sasl_passwd# with the following content:
 
 [.programlisting]
 ....
 [smtp.freebsd.org]:587          yourusername:yourpassword
 ....
 
 If the email server is used by other people, you may want to prevent them from sending e-mails from your address. To achieve this, add this to your [.filename]#main.cf#:
 
 [.programlisting]
 ....
 smtpd_sender_login_maps = hash:/usr/local/etc/postfix/sender_login_maps
 smtpd_sender_restrictions = reject_known_sender_login_mismatch
 ....
 
 Create [.filename]#/usr/local/etc/postfix/sender_login_maps# with the following content:
 
 [.programlisting]
 ....
 yourusername@FreeBSD.org yourlocalusername
 ....
 
 Where _yourlocalusername_ is the SASL username used to connect to the local instance of Postfix.
 ====
 
 [[smtp-setup-local-opensmtpd]]
 .Using OpenSMTPD
 [example]
 ====
 
 To tell a local OpenSMTPD instance that anything from `_yourusername_@FreeBSD.org` should be forwarded to the FreeBSD.org servers, add this to your [.filename]#smtpd.conf#:
 
 [.programlisting]
 ....
 action "freebsd" relay host smtp+tls://freebsd@smtp.freebsd.org:587 auth <secrets>
 match from any auth yourlocalusername mail-from "_yourusername_@freebsd.org" for any action "freebsd"
 ....
 
 Where _yourlocalusername_ is the SASL username used to connect to the local instance of OpenSMTPD.
 
 Create [.filename]#/usr/local/etc/mail/secrets# with the following content:
 
 [.programlisting]
 ....
 freebsd	yourusername:yourpassword
 ....
 
 ====
 
 [[mentors]]
 === Mentors
 
 All new developers have a mentor assigned to them for the first few months.
 A mentor is responsible for teaching the mentee the rules and conventions of the project and guiding their first steps in the developer community.
 The mentor is also personally responsible for the mentee's actions during this initial period.
 
 For committers: do not commit anything without first getting mentor approval.
 Document that approval with an `Approved by:` line in the commit message.
 
 When the mentor decides that a mentee has learned the ropes and is ready to commit on their own, the mentor announces it with a commit to [.filename]#mentors#.
 This file is in the [.filename]#admin# orphan branch of each repository.
 Detailed information on how to access these branches can be found in link:{handbook}mirror/#admin-branch["admin" branch].
 
 [[pre-commit-review]]
 == Pre-Commit Review
 
 Code review is one way to increase the quality of software.
 The following guidelines apply to commits to the `head` (-CURRENT) branch of the `src` repository.
 Other branches and the `ports` and `docs` trees have their own review policies, but these guidelines generally apply to commits requiring review:
 
 * All non-trivial changes should be reviewed before they are committed to the repository.
 * Reviews may be conducted by email, in Bugzilla, in Phabricator, or by another mechanism. Where possible, reviews should be public.
 * The developer responsible for a code change is also responsible for making all necessary review-related changes.
 * Code review can be an iterative process, which continues until the patch is ready to be committed. Specifically, once a patch is sent out for review, it should receive an explicit "looks good" before it is committed. So long as it is explicit, this can take whatever form makes sense for the review method.
 * Timeouts are not a substitute for review.
 
 Sometimes code reviews will take longer than you would hope for, especially for larger features. Accepted ways to speed up review times for your patches are:
 
 * Review other people's patches. If you help out, everybody will be more willing to do the same for you; goodwill is our currency.
 * Ping the patch. If it is urgent, provide reasons why it is important to you to get this patch landed and ping it every couple of days. If it is not urgent, the common courtesy ping rate is one week. Remember that you are asking for valuable time from other professional developers.
 * Ask for help on mailing lists, IRC, etc. Others may be able to either help you directly, or suggest a reviewer.
 * Split your patch into multiple smaller patches that build on each other. The smaller your patch, the higher the probability that somebody will take a quick look at it.
-+ 
++
 When making large changes, it is helpful to keep this in mind from the beginning of the effort as breaking large changes into smaller ones is often difficult after the fact.
 
 Developers should participate in code reviews as both reviewers and reviewees.
 If someone is kind enough to review your code, you should return the favor for someone else.
 Note that while anyone is welcome to review and give feedback on a patch, only an appropriate subject-matter expert can approve a change.
 This will usually be a committer who works with the code in question on a regular basis.
 
 In some cases, no subject-matter expert may be available.
 In those cases, a review by an experienced developer is sufficient when coupled with appropriate testing.
 
 [[commit-log-message]]
 == Commit Log Messages
 
 This section contains some suggestions and traditions for how commit logs are formatted.
 
 === Why are commit messages important?
 
 When you commit a change in Git, Subversion, or another version control system (VCS), you're prompted to write some text describing the commit -- a commit message.
 How important is this commit message? Should you spend some significant effort writing it? Does it really matter if you write simply fixed a bug?
 
 Most projects have more than one developer and last for some length of time.
 Commit messages are a very important method of communicating with other developers, in the present and for the future.
 
 FreeBSD has hundreds of active developers and hundreds of thousands of commits spanning decades of history.
 Over that time the developer community has learned how valuable good commit messages are; sometimes these are hard-learned lessons.
 
 Commit messages serve at least three purposes:
 
 * Communicating with other developers
 +
 FreeBSD commits generate email to various mailing lists.
 These include the commit message along with a copy of the patch itself.
 Commit messages are also viewed through commands like git log.
 These serve to make other developers aware of changes that are ongoing; that other developer may want to test the change, may have an interest in the topic and will want to review in more detail, or may have their own projects underway that would benefit from interaction.
 
 * Making Changes Discoverable
 +
 In a large project with a long history it may be difficult to find changes of interest when investigating an issue or change in behaviour.
 Verbose, detailed commit messages allow searches for changes that might be relevant.
 For example, `git log --since 1year --grep 'USB timeout'`.
 
 * Providing historical documentation
 +
 Commit messages serve to document changes for future developers, perhaps years or decades later.
 This future developer may even be you, the original author.
 A change that seems obvious today may be decidedly not so much later on.
 
 The `git blame` command annotates each line of a source file with the change (hash and subject line) that brought it in.
 
 Having established the importance, here are elements of a good FreeBSD commit message:
 
 === Start with a subject line
 
 Commit messages should start with a single-line subject that briefly summarizes the change.
 The subject should, by itself, allow the reader to quickly determine if the change is of interest or not.
 
 === Keep subject lines short
 
 The subject line should be as short as possible while still retaining the required information.
 This is to make browsing Git log more efficient, and so that git log --oneline can display the short hash and subject on a single 80-column line.
 A good rule of thumb is to stay below 63 characters, and aim for about 50 or fewer if possible.
 
 === Prefix the subject line with a component, if applicable
 
 If the change relates to a specific component the subject line may be prefixed with that component name and a colon (:).
 
 ✓ `foo: Add -k option to keep temporary data`
 
 Include the prefix in the 63-character limit suggested above, so that `git log --oneline` avoids wrapping.
 
 === Capitalize the first letter of the subject
 
 Capitalize the first letter of the subject itself.
 The prefix, if any, is not capitalized unless necessary (e.g., `USB:` is capitalized).
 
 === Do not end the subject line with punctuation
 
 Do not end with a period or other punctuation.
 In this regard the subject line is like a newspaper headline.
 
 === Separate the subject and body with a blank line
 
 Separate the body from the subject with a blank line.
 
 Some trivial commits do not require a body, and will have only a subject.
 
 ✓ `ls: Fix typo in usage text`
 
 === Limit messages to 72 columns
 
 `git log` and `git format-patch` indent the commit message by four spaces.
 Wrapping at 72 columns provides a matching margin on the right edge.
 Limiting messages to 72 characters also keeps the commit message in formatted patches below RFC 2822's suggested email line length limit of 78 characters.
 This limit works well with a variety of tools that may render commit messages; line wrapping might be inconsistent with longer line length.
 
 === Use the present tense, imperative mood
 
 This facilitates short subject lines and provides consistency, including with automatically generated commit messages (e.g., as generated by git revert).
 This is important when reading a list of commit subjects.
 Think of the subject as finishing the sentence "when applied, this change will ...".
 
 ✓ `foo: Implement the -k (keep) option` +
 ✗ `foo: Implemented the -k option` +
 ✗ `This change implements the -k option in foo` +
 ✗ `-k option added`
 
 === Focus on what and why, not how
 
 Explain what the change accomplishes and why it is being done, rather than how.
 
 Do not assume that the reader is familiar with the issue.
 Explain the background and motivation for the change.
 Include benchmark data if you have it.
 
 If there are limitations or incomplete aspects of the change, describe them in the commit message.
 
 === Consider whether parts of the commit message could be code comments instead
 
 Sometimes while writing a commit message you may find yourself writing a sentence or two explaining some tricky or confusing aspect of the change. When this happens consider whether it would be valuable to have that explanation as a comment in the code itself.
 
 === Write commit messages for your future self
 
 While writing the commit message for a change you have all of the context in mind - what prompted the change, alternate approaches that were considered and rejected, limitations of the change, and so on.
 Imagine yourself revisiting the change a year or two in the future, and write the commit message in a way that would provide that necessary context.
 
 === Commit messages should stand alone
 
 You may include references to mailing list postings, benchmark result web sites, or code review links.
 However, the commit message should contain all of the relevant information in case these references are no longer available in the future.
 
 Similarly, a commit may refer to a previous commit, for example in the case of a bug fix or revert.
 In addition to the commit identifier (revision or hash), include the subject line from the referenced commit (or another suitable brief reference).
 With each VCS migration (from CVS to Subversion to Git) revision identifiers from previous systems may become difficult to follow.
 
 === Include appropriate metadata in a footer
 
 As well as including an informative message with each commit, some additional information may be needed.
 
 This information consists of one or more lines containing the key word or phrase, a colon, tabs for formatting, and then the additional information.
 
 The key words or phrases are:
 
 [.informaltable]
 [cols="20%,80%", frame="none"]
 |===
 
 |`PR:`
 |The problem report (if any) which is affected (typically, by being closed) by this commit. Multiple PRs may be specified on one line, separated by commas or spaces.
 
 |`Reported by:`
 |The name and e-mail address of the person that reported the issue; for developers, just the username on the FreeBSD cluster.
 Typically used when there is no PR, for example if the issue was reported on
 a mailing list.
 
 |`Submitted by:`
 |The name and e-mail address of the person that submitted the fix; for developers, just the username on the FreeBSD cluster.
 
 Typically not used with Git; submitted patches should
 have the author set by using `git commit --author`.
 
 If the submitter is the maintainer of the port being committed, include "(maintainer)" after the email address.
 
 Avoid obfuscating the email address of the submitter as this adds additional work when searching logs.
 
 |`Reviewed by:`
 |The name and e-mail address of the person or people that reviewed the change; for developers, just the username on the FreeBSD cluster. If a patch was submitted to a mailing list for review, and the review was favorable, then just include the list name.
 
 |`Tested by:`
 |The name and e-mail address of the person or people that tested the change; for developers, just the username on the FreeBSD cluster.
 
 |`Approved by:`
 a|
 
 The name and e-mail address of the person or people that approved the change; for developers, just the username on the FreeBSD cluster.
 
 There are several cases where approval is customary:
 
 * while a new committer is under mentorship
 * commits to an area of the tree to which you do not usually commit
 * during a release cycle
 * committing to a repo where you do not hold a commit bit (e.g. src committer committing to docs)
 
 While under mentorship, get mentor approval before the commit. Enter the mentor's username in this field, and note that they are a mentor:
 
 [source,shell]
 ....
 Approved by: username-of-mentor (mentor)
 ....
 
 If a team approved these commits then include the team name followed by the username of the approver in parentheses. For example:
 
 [source,shell]
 ....
 Approved by: re (username)
 ....
 
 |`Obtained from:`
 |The name of the project (if any) from which the code was obtained. Do not use this line for the name of an individual person.
 
 |`Fixes:`
 |The Git short hash and the title line of a commit that is fixed by this change as returned by `git log -n 1 --oneline GIT-COMMIT-HASH`.
 
 |`MFC after:`
 |To receive an e-mail reminder to MFC at a later date, specify the number of days, weeks, or months after which an MFC is planned.
 
 |`MFC to:`
 |If the commit should be merged to a subset of stable branches, specify the branch names.
 
 |`MFC with:`
 |If the commit should be merged together with a previous one in a single MFC commit (for example, where this commit corrects a bug in the previous change), specify the corresponding Git hash.
 
 |`MFH:`
 |If the commit is to be merged into a ports quarterly branch name, specify the quarterly branch. For example `2021Q2`.
 
 |`Relnotes:`
 |If the change is a candidate for inclusion in the release notes for the next release from the branch, set to `yes`.
 
 |`Security:`
 |If the change is related to a security vulnerability or security exposure, include one or more references or a description of the issue. If possible, include a VuXML URL or a CVE ID.
 
 |`Event:`
 |The description for the event where this commit was made. If this is a recurring event, add the year or even the month to it. For example, this could be `FooBSDcon 2019`. The idea behind this line is to put recognition to conferences, gatherings, and other types of meetups and to show that these are useful to have. Please do not use the `Sponsored by:` line for this as that is meant for organizations sponsoring certain features or developers working on them.
 
 |`Sponsored by:`
 |Sponsoring organizations for this change, if any. Separate multiple organizations with commas. If only a portion of the work was sponsored, or different amounts of sponsorship were provided to different authors, please give appropriate credit in parentheses after each sponsor name. For example, `Example.com (alice, code refactoring), Wormulon (bob), Momcorp (cindy)` shows that Alice was sponsored by Example.com to do code refactoring, while Wormulon sponsored Bob's work and Momcorp sponsored Cindy's work. Other authors were either not sponsored or chose not to list sponsorship.
 
 |`Differential Revision:`
 |The full URL of the Phabricator review. This line __must be the last line__. For example: `https://reviews.freebsd.org/D1708`.
 
 |`Signed-off-by:`
 |ID certifies compliance with https://developercertificate.org/
 
 |===
 
 .Commit Log for a Commit Based on a PR
 [example]
 ====
 
 The commit is based on a patch from a PR submitted by John Smith.
 The commit message "PR" field is filled.
 
 [.programlisting]
 ....
 ...
 
 PR:		12345
 ....
 
 The committer sets the author of the patch with `git commit --author "John Smith <John.Smith@example.com>"`.
 
 ====
 
 .Commit Log for a Commit Needing Review
 [example]
 ====
 
 The virtual memory system is being changed.
 After posting patches to the appropriate mailing list (in this case, `freebsd-arch`) and the changes have been approved.
 
 [.programlisting]
 ....
 ...
 
 Reviewed by:	-arch
 ....
 
 ====
 
 .Commit Log for a Commit Needing Approval
 [example]
 ====
 
 Commit a port, after working with the listed MAINTAINER, who said to go ahead and commit.
 
 [.programlisting]
 ....
 ...
 
 Approved by:	abc (maintainer)
 ....
 
 Where _abc_ is the account name of the person who approved.
 ====
 
 .Commit Log for a Commit Bringing in Code from OpenBSD
 [example]
 ====
 
 Committing some code based on work done in the OpenBSD project.
 
 [.programlisting]
 ....
 ...
 
 Obtained from:	OpenBSD
 ....
 
 ====
 
 .Commit Log for a Change to FreeBSD-CURRENT with a Planned Commit to FreeBSD-STABLE to Follow at a Later Date.
 [example]
 ====
 
 Committing some code which will be merged from FreeBSD-CURRENT into the FreeBSD-STABLE branch after two weeks.
 
 [.programlisting]
 ....
 ...
 
 MFC after:	2 weeks
 ....
 
 Where _2_ is the number of days, weeks, or months after which an MFC is planned. The _weeks_ option may be `day`, `days`, `week`, `weeks`, `month`, `months`.
 ====
 
 It is often necessary to combine these.
 
 Consider the situation where a user has submitted a PR containing code from the NetBSD project.
 Looking at the PR, the developer sees it is not an area of the tree they normally work in, so they have the change reviewed by the `arch` mailing list.
 Since the change is complex, the developer opts to MFC after one month to allow adequate testing.
 
 The extra information to include in the commit would look something like
 
 .Example Combined Commit Log
 [example]
 ====
 
 [.programlisting]
 ....
 PR:		54321
 Reviewed by:	-arch
 Obtained from:	NetBSD
 MFC after:	1 month
 Relnotes:	yes
 ....
 
 ====
 
 [[pref-license]]
 == Preferred License for New Files
 
 The FreeBSD Project's full license policy can be found at link:https://www.FreeBSD.org/internal/software-license/[https://www.FreeBSD.org/internal/software-license].
 The rest of this section is intended to help you get started.
 As a rule, when in doubt, ask.
 It is much easier to give advice than to fix the source tree.
 
 The FreeBSD Project suggests and uses this text as the preferred license scheme:
 
 [.programlisting]
 ....
 /*-
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) [year] [your name]
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  * [id for your version control system, if any]
  */
 ....
 
 The FreeBSD project strongly discourages the so-called "advertising clause" in new code.
 Due to the large number of contributors to the FreeBSD project, complying with this clause for many commercial vendors has become difficult.
 If you have code in the tree with the advertising clause, please consider removing it.
 In fact, please consider using the above license for your code.
 
 The FreeBSD project discourages completely new licenses and variations on the standard licenses.
 New licenses require the approval of the {core-email} to reside in the main repository.
 The more different licenses that are used in the tree, the more problems that this causes to those wishing to utilize this code, typically from unintended consequences from a poorly worded license.
 
 Project policy dictates that code under some non-BSD licenses must be placed only in specific sections of the repository, and in some cases, compilation must be conditional or even disabled by default.
 For example, the GENERIC kernel must be compiled under only licenses identical to or substantially similar to the BSD license.
 GPL, APSL, CDDL, etc, licensed software must not be compiled into GENERIC.
 
 Developers are reminded that in open source, getting "open" right is just as important as getting "source" right, as improper handling of intellectual property has serious consequences.
 Any questions or concerns should immediately be brought to the attention of the core team.
 
 [[tracking.license.grants]]
 == Keeping Track of Licenses Granted to the FreeBSD Project
 
 Various software or data exist in the repositories where the FreeBSD project has been granted a special licence to be able to use them.
 A case in point are the Terminus fonts for use with man:vt[4].
 Here the author Dimitar Zhekov has allowed us to use the "Terminus BSD Console" font under a 2-clause BSD license rather than the regular Open Font License he normally uses.
 
 It is clearly sensible to keep a record of any such license grants.
 To that end, the {core-email} has decided to keep an archive of them.
 Whenever the FreeBSD project is granted a special license we require the {core-email} to be notified.
 Any developers involved in arranging such a license grant, please send details to the {core-email} including:
 
 * Contact details for people or organizations granting the special license.
 * What files, directories etc. in the repositories are covered by the license grant including the revision numbers where any specially licensed material was committed.
 * The date the license comes into effect from. Unless otherwise agreed, this will be the date the license was issued by the authors of the software in question.
 * The license text.
 * A note of any restrictions, limitations or exceptions that apply specifically to FreeBSD's usage of the licensed material.
 * Any other relevant information.
 
 Once the {core-email} is satisfied that all the necessary details have been gathered and are correct, the secretary will send a PGP-signed acknowledgement of receipt including the license details.
 This receipt will be persistently archived and serve as our permanent record of the license grant.
 
 The license archive should contain only details of license grants; this is not the place for any discussions around licensing or other subjects.
 Access to data within the license archive will be available on request to the {core-email}.
 
 [[spdx.tags]]
 == SPDX Tags in the tree
 
 The project uses https://spdx.dev[SPDX] tags in our source base.
 At present, these tags are indented to help automated tools reconstruct license requirements mechanically.
 All _SPDX-License-Identifier_ tags in the tree should be considered to be informative.
 All files in the FreeBSD source tree with these tags also have a copy of the license which governs use of that file.
 In the event of a discrepency, the verbatim license is controlling.
 The project tries to follow the https://spdx.github.io/spdx-spec/[SPDX Specification, Version 2.2].
 How to mark source files and valid algebraic expressions are found in https://spdx.github.io/spdx-spec/appendix-IV-SPDX-license-expressions/[Appendix IV] and https://spdx.github.io/spdx-spec/appendix-V-using-SPDX-short-identifiers-in-source-files/[Appendix V].
 The project draws identifiers from SPDX's list of valid https://spdx.org/licenses/[short license identifiers].
 The project uses only the _SPDX-License-Identifier_ tag.
 
 As of March 2021, approximately 25,000 out of 90,000 files in the tree have been marked.
 [[developer.relations]]
 == Developer Relations
 
 When working directly on your own code or on code which is already well established as your responsibility, then there is probably little need to check with other committers before jumping in with a commit.
 Working on a bug in an area of the system which is clearly orphaned (and there are a few such areas, to our shame), the same applies.
 When modifying parts of the system which are maintained, formally, or informally, consider asking for review just as a developer would have before becoming a committer.
 For ports, contact the listed `MAINTAINER` in the [.filename]#Makefile#.
 
 To determine if an area of the tree is maintained, check the MAINTAINERS file at the root of the tree.
 If nobody is listed, scan the revision history to see who has committed changes in the past.
 An example script that lists each person who has committed to a given file along with the number of commits each person has made can be found at on `freefall` at [.filename]#~eadler/bin/whodid#.
 If queries go unanswered or the committer otherwise indicates a lack of interest in the area affected, go ahead and commit it.
 
 [IMPORTANT]
 ====
 Avoid sending private emails to maintainers.
 Other people might be interested in the conversation, not just the final output.
 ====
 
 If there is any doubt about a commit for any reason at all, have it reviewed before committing.
 Better to have it flamed then and there rather than when it is part of the repository.
 If a commit does results in controversy erupting, it may be advisable to consider backing the change out again until the matter is settled.
 Remember, with a version control system we can always change it back.
 
 Do not impugn the intentions of others.
 If they see a different solution to a problem, or even a different problem, it is probably not because they are stupid, because they have questionable parentage, or because they are trying to destroy hard work, personal image, or FreeBSD, but basically because they have a different outlook on the world. 
 Different is good.
 
 Disagree honestly.
 Argue your position from its merits, be honest about any shortcomings it may have, and be open to seeing their solution, or even their vision of the problem, with an open mind.
 
 Accept correction.
 We are all fallible.
 When you have made a mistake, apologize and get on with life.
 Do not beat up yourself, and certainly do not beat up others for your mistake.
 Do not waste time on embarrassment or recrimination, just fix the problem and move on.
 
 Ask for help.
 Seek out (and give) peer reviews.
 One of the ways open source software is supposed to excel is in the number of eyeballs applied to it; this does not apply if nobody will review code.
 
 [[if-in-doubt]]
 == If in Doubt...
 
 When unsure about something, whether it be a technical issue or a project convention be sure to ask.
 If you stay silent you will never make progress.
 
 If it relates to a technical issue ask on the public mailing lists.
 Avoid the temptation to email the individual person that knows the answer.
 This way everyone will be able to learn from the question and the answer.
 
 For project specific or administrative questions ask, in order:
 
 * Your mentor or former mentor.
 * An experienced committer on IRC, email, etc.
 * Any team with a "hat", as they can give you a definitive answer.
 * If still not sure, ask on {developers-name}.
 
 Once your question is answered, if no one pointed you to documentation that spelled out the answer to your question, document it, as others will have the same question.
 
 [[bugzilla]]
 == Bugzilla
 
 The FreeBSD Project utilizes Bugzilla for tracking bugs and change requests.
 Be sure that if you commit a fix or suggestion found in the PR database to close it.
 It is also considered nice if you take time to close any PRs associated with your commits, if appropriate.
 
 Committers with non-``FreeBSD.org`` Bugzilla accounts can have the old account merged with the `FreeBSD.org` account by following these steps:
 
 [.procedure]
 ====
 . Log in using your old account.
 . Open new bug. Choose `Services` as the Product, and `Bug Tracker` as the Component. In bug description list accounts you wish to be merged.
 . Log in using `FreeBSD.org` account and post comment to newly opened bug to confirm ownership. See <<kerberos-ldap>> for more details on how to generate or set a password for your `FreeBSD.org` account.
 . If there are more than two accounts to merge, post comments from each of them.
 ====
 
 You can find out more about Bugzilla at:
 
 * link:{pr-guidelines}[FreeBSD Problem Report Handling Guidelines]
 * link:https://www.FreeBSD.org/support/[https://www.FreeBSD.org/support]
 
 [[phabricator]]
 == Phabricator
 
 The FreeBSD Project utilizes https://reviews.freebsd.org[Phabricator] for code review requests.
 See the https://wiki.freebsd.org/CodeReview[CodeReview] wiki page for details.
 
 Committers with non-``FreeBSD.org`` Phabricator accounts can have the old account renamed to the ``FreeBSD.org`` account by following these steps:
 
 [.procedure]
 ====
 . Change your Phabricator account email to your `FreeBSD.org` email.
 . Open new bug on our bug tracker using your `FreeBSD.org` account, see <<bugzilla>> for more information. Choose `Services` as the Product, and `Code Review` as the Component. In bug description request that your Phabricator account be renamed, and provide a link to your Phabricator user. For example, `https://reviews.freebsd.org/p/bob_example.com/`
 ====
 
 [IMPORTANT]
 ====
 Phabricator accounts cannot be merged, please do not open a new account.
 ====
 
 [[people]]
 == Who's Who
 
 Besides the repository meisters, there are other FreeBSD project members and teams whom you will probably get to know in your role as a committer. Briefly, and by no means all-inclusively, these are:
 
 `{doceng}`::
 doceng is the group responsible for the documentation build infrastructure, approving new documentation committers, and ensuring that the FreeBSD website and documentation on the FTP site is up to date with respect to the Subversion tree.
 It is not a conflict resolution body.
 The vast majority of documentation related discussion takes place on the {freebsd-doc}.
 More details regarding the doceng team can be found in its https://www.FreeBSD.org/internal/doceng/[charter].
 Committers interested in contributing to the documentation should familiarize themselves with the link:{fdp-primer}[Documentation Project Primer].
 
 `{re-members}`::
 These are the members of the `{re}`.
 This team is responsible for setting release deadlines and controlling the release process.
 During code freezes, the release engineers have final authority on all changes to the system for whichever branch is pending release status.
 If there is something you want merged from FreeBSD-CURRENT to FreeBSD-STABLE (whatever values those may have at any given time), these are the people to talk to about it.
 
 `{so}`::
 `{so-name}` is the link:https://www.FreeBSD.org/security/[FreeBSD Security Officer] and oversees the `{security-officer}`.
 
 `{wollman}`::
 If you need advice on obscure network internals or are not sure of some potential change to the networking subsystem you have in mind, Garrett is someone to talk to.
 Garrett is also very knowledgeable on the various standards applicable to FreeBSD.
 
 {committers-name}::
 {svn-src-all}, {svn-ports-all} and {svn-doc-all} are the mailing lists that the version control system uses to send commit messages to.
 _Never_ send email directly to these lists.
 Only send replies to this list when they are short and are directly related to a commit.
 
 {developers-name}::
 All committers are subscribed to -developers.
 This list was created to be a forum for the committers "community" issues.
 Examples are Core voting, announcements, etc.
 +
 The {developers-name} is for the exclusive use of FreeBSD committers.
 To develop FreeBSD, committers must have the ability to openly discuss matters that will be resolved before they are publicly announced.
 Frank discussions of work in progress are not suitable for open publication and may harm FreeBSD.
 +
 All FreeBSD committers are expected not to not publish or forward messages from the {developers-name} outside the list membership without permission of all of the authors.
 Violators will be removed from the {developers-name}, resulting in a suspension of commit privileges.
 Repeated or flagrant violations may result in permanent revocation of commit privileges.
 +
 This list is _not_ intended as a place for code reviews or for any technical discussion.
 In fact using it as such hurts the FreeBSD Project as it gives a sense of a closed list where general decisions affecting all of the FreeBSD using community are made without being "open".
 Last, but not least __never, never ever, email the {developers-name} and CC:/BCC: another FreeBSD list__.
 Never, ever email another FreeBSD email list and CC:/BCC: the {developers-name}.
 Doing so can greatly diminish the benefits of this list.
 [[ssh.guide]]
 == SSH Quick-Start Guide
 
 [.procedure]
 ====
 . If you do not wish to type your password in every time you use man:ssh[1], and you use keys to authenticate, man:ssh-agent[1] is there for your convenience. If you want to use man:ssh-agent[1], make sure that you run it before running other applications. X users, for example, usually do this from their [.filename]#.xsession# or [.filename]#.xinitrc#. See man:ssh-agent[1] for details.
 . Generate a key pair using man:ssh-keygen[1]. The key pair will wind up in your [.filename]#$HOME/.ssh/# directory.
 +
 [IMPORTANT]
 ======
 Only ECDSA, Ed25519 or RSA keys are supported.
 ======
 . Send your public key ([.filename]#$HOME/.ssh/id_ecdsa.pub#, [.filename]#$HOME/.ssh/id_ed25519.pub#, or [.filename]#$HOME/.ssh/id_rsa.pub#) to the person setting you up as a committer so it can be put into [.filename]#yourlogin# in [.filename]#/etc/ssh-keys/# on `freefall`.
 ====
 
 Now man:ssh-add[1] can be used for authentication once per session.
 It prompts for the private key's pass phrase, and then stores it in the authentication agent (man:ssh-agent[1]).
 Use `ssh-add -d` to remove keys stored in the agent.
 
 Test with a simple remote command: `ssh freefall.FreeBSD.org ls /usr`.
 
 For more information, see package:security/openssh-portable[], man:ssh[1], man:ssh-add[1], man:ssh-agent[1], man:ssh-keygen[1], and man:scp[1].
 
 For information on adding, changing, or removing man:ssh[1] keys, see https://wiki.freebsd.org/clusteradm/ssh-keys[this article].
 
 [[coverity]]
 == Coverity(R) Availability for FreeBSD Committers
 
 All FreeBSD developers can obtain access to Coverity analysis results of all FreeBSD Project software.
 All who are interested in obtaining access to the analysis results of the automated Coverity runs, can sign up at http://scan.coverity.com/[Coverity Scan].
 
 The FreeBSD wiki includes a mini-guide for developers who are interested in working with the Coverity(R) analysis reports: https://wiki.freebsd.org/CoverityPrevent[https://wiki.freebsd.org/CoverityPrevent].
 Please note that this mini-guide is only readable by FreeBSD developers, so if you cannot access this page, you will have to ask someone to add you to the appropriate Wiki access list.
 
 Finally, all FreeBSD developers who are going to use Coverity(R) are always encouraged to ask for more details and usage information, by posting any questions to the mailing list of the FreeBSD developers.
 
 [[rules]]
 == The FreeBSD Committers' Big List of Rules
 
 Everyone involved with the FreeBSD project is expected to abide by the _Code of Conduct_ available from link:https://www.FreeBSD.org/internal/code-of-conduct/[https://www.FreeBSD.org/internal/code-of-conduct].
 As committers, you form the public face of the project, and how you behave has a vital impact on the public perception of it.
 This guide expands on the parts of the _Code of Conduct_ specific to committers.
 
 . Respect other committers.
 . Respect other contributors.
 . Discuss any significant change _before_ committing.
 . Respect existing maintainers (if listed in the `MAINTAINER` field in [.filename]#Makefile# or in [.filename]#MAINTAINER# in the top-level directory).
 . Any disputed change must be backed out pending resolution of the dispute if requested by a maintainer. Security related changes may override a maintainer's wishes at the Security Officer's discretion.
 . Changes go to FreeBSD-CURRENT before FreeBSD-STABLE unless specifically permitted by the release engineer or unless they are not applicable to FreeBSD-CURRENT. Any non-trivial or non-urgent change which is applicable should also be allowed to sit in FreeBSD-CURRENT for at least 3 days before merging so that it can be given sufficient testing. The release engineer has the same authority over the FreeBSD-STABLE branch as outlined for the maintainer in rule #5.
 . Do not fight in public with other committers; it looks bad.
 . Respect all code freezes and read the `committers` and `developers` mailing lists in a timely manner so you know when a code freeze is in effect.
 . When in doubt on any procedure, ask first!
 . Test your changes before committing them.
 . Do not commit to contributed software without _explicit_ approval from the respective maintainers.
 
 As noted, breaking some of these rules can be grounds for suspension or, upon repeated offense, permanent removal of commit privileges.
 Individual members of core have the power to temporarily suspend commit privileges until core as a whole has the chance to review the issue.
 In case of an "emergency" (a committer doing damage to the repository), a temporary suspension may also be done by the repository meisters.
 Only a 2/3 majority of core has the authority to suspend commit privileges for longer than a week or to remove them permanently.
 This rule does not exist to set core up as a bunch of cruel dictators who can dispose of committers as casually as empty soda cans, but to give the project a kind of safety fuse.
 If someone is out of control, it is important to be able to deal with this immediately rather than be paralyzed by debate.
 In all cases, a committer whose privileges are suspended or revoked is entitled to a "hearing" by core, the total duration of the suspension being determined at that time.
 A committer whose privileges are suspended may also request a review of the decision after 30 days and every 30 days thereafter (unless the total suspension period is less than 30 days).
 A committer whose privileges have been revoked entirely may request a review after a period of 6 months has elapsed.
 This review policy is _strictly informal_ and, in all cases, core reserves the right to either act on or disregard requests for review if they feel their original decision to be the right one.
 
 In all other aspects of project operation, core is a subset of committers and is bound by the __same rules__.
 Just because someone is in core this does not mean that they have special dispensation to step outside any of the lines painted here; core's "special powers" only kick in when it acts as a group, not on an individual basis.
 As individuals, the core team members are all committers first and core second.
 
 === Details
 
 [[respect]]
 . Respect other committers.
-+ 
++
 This means that you need to treat other committers as the peer-group developers that they are.
 Despite our occasional attempts to prove the contrary, one does not get to be a committer by being stupid and nothing rankles more than being treated that way by one of your peers.
 Whether we always feel respect for one another or not (and everyone has off days), we still have to _treat_ other committers with respect at all times, on public forums and in private email.
-+ 
++
 Being able to work together long term is this project's greatest asset, one far more important than any set of changes to the code, and turning arguments about code into issues that affect our long-term ability to work harmoniously together is just not worth the trade-off by any conceivable stretch of the imagination.
-+ 
++
 To comply with this rule, do not send email when you are angry or otherwise behave in a manner which is likely to strike others as needlessly confrontational.
 First calm down, then think about how to communicate in the most effective fashion for convincing the other persons that your side of the argument is correct, do not just blow off some steam so you can feel better in the short term at the cost of a long-term flame war.
 Not only is this very bad "energy economics", but repeated displays of public aggression which impair our ability to work well together will be dealt with severely by the project leadership and may result in suspension or termination of your commit privileges.
 The project leadership will take into account both public and private communications brought before it.
 It will not seek the disclosure of private communications, but it will take it into account if it is volunteered by the committers involved in the complaint.
-+ 
++
 All of this is never an option which the project's leadership enjoys in the slightest, but unity comes first.
 No amount of code or good advice is worth trading that away.
 . Respect other contributors.
-+ 
++
 You were not always a committer.
 At one time you were a contributor.
 Remember that at all times.
 Remember what it was like trying to get help and attention.
 Do not forget that your work as a contributor was very important to you.
 Remember what it was like. Do not discourage, belittle, or demean contributors.
 Treat them with respect. They are our committers in waiting.
 They are every bit as important to the project as committers.
 Their contributions are as valid and as important as your own.
 After all, you made many contributions before you became a committer.
 Always remember that.
-+ 
++
 Consider the points raised under <<respect,Respect other committers>> and apply them also to contributors.
 . Discuss any significant change _before_ committing.
-+ 
++
 The repository is not where changes are initially submitted for correctness or argued over, that happens first in the mailing lists or by use of the Phabricator service.
 The commit will only happen once something resembling consensus has been reached.
 This does not mean that permission is required before correcting every obvious syntax error or manual page misspelling, just that it is good to develop a feel for when a proposed change is not quite such a no-brainer and requires some feedback first.
 People really do not mind sweeping changes if the result is something clearly better than what they had before, they just do not like being _surprised_ by those changes.
 The very best way of making sure that things are on the right track is to have code reviewed by one or more other committers.
-+ 
++
 When in doubt, ask for review!
 . Respect existing maintainers if listed.
-+ 
++
 Many parts of FreeBSD are not "owned" in the sense that any specific individual will jump up and yell if you commit a change to "their" area, but it still pays to check first.
 One convention we use is to put a maintainer line in the [.filename]#Makefile# for any package or subtree which is being actively maintained by one or more people; see link:{developers-handbook}#policies[Source Tree Guidelines and Policies] for documentation on this.
 Where sections of code have several maintainers, commits to affected areas by one maintainer need to be reviewed by at least one other maintainer.
 In cases where the "maintainer-ship" of something is not clear, look at the repository logs for the files in question and see if someone has been working recently or predominantly in that area.
 . Any disputed change must be backed out pending resolution of the dispute if requested by a maintainer. Security related changes may override a maintainer's wishes at the Security Officer's discretion.
-+ 
++
 This may be hard to swallow in times of conflict (when each side is convinced that they are in the right, of course) but a version control system makes it unnecessary to have an ongoing dispute raging when it is far easier to simply reverse the disputed change, get everyone calmed down again and then try to figure out what is the best way to proceed.
 If the change turns out to be the best thing after all, it can be easily brought back.
 If it turns out not to be, then the users did not have to live with the bogus change in the tree while everyone was busily debating its merits.
 People _very_ rarely call for back-outs in the repository since discussion generally exposes bad or controversial changes before the commit even happens, but on such rare occasions the back-out should be done without argument so that we can get immediately on to the topic of figuring out whether it was bogus or not.
 . Changes go to FreeBSD-CURRENT before FreeBSD-STABLE unless specifically permitted by the release engineer or unless they are not applicable to FreeBSD-CURRENT. Any non-trivial or non-urgent change which is applicable should also be allowed to sit in FreeBSD-CURRENT for at least 3 days before merging so that it can be given sufficient testing. The release engineer has the same authority over the FreeBSD-STABLE branch as outlined in rule #5.
-+ 
++
 This is another "do not argue about it" issue since it is the release engineer who is ultimately responsible (and gets beaten up) if a change turns out to be bad.
 Please respect this and give the release engineer your full cooperation when it comes to the FreeBSD-STABLE branch.
 The management of FreeBSD-STABLE may frequently seem to be overly conservative to the casual observer, but also bear in mind the fact that conservatism is supposed to be the hallmark of FreeBSD-STABLE and different rules apply there than in FreeBSD-CURRENT.
 There is also really no point in having FreeBSD-CURRENT be a testing ground if changes are merged over to FreeBSD-STABLE immediately.
 Changes need a chance to be tested by the FreeBSD-CURRENT developers, so allow some time to elapse before merging unless the FreeBSD-STABLE fix is critical, time sensitive or so obvious as to make further testing unnecessary (spelling fixes to manual pages, obvious bug/typo fixes, etc.) In other words, apply common sense.
-+ 
++
 Changes to the security branches (for example, `releng/9.3`) must be approved by a member of the `{security-officer}`, or in some cases, by a member of the `{re}`.
 . Do not fight in public with other committers; it looks bad.
-+ 
++
 This project has a public image to uphold and that image is very important to all of us, especially if we are to continue to attract new members.
 There will be occasions when, despite everyone's very best attempts at self-control, tempers are lost and angry words are exchanged.
 The best thing that can be done in such cases is to minimize the effects of this until everyone has cooled back down.
 Do not air angry words in public and do not forward private correspondence or other private communications to public mailing lists, mail aliases, instant messaging channels or social media sites.
 What people say one-to-one is often much less sugar-coated than what they would say in public, and such communications therefore have no place there - they only serve to inflame an already bad situation.
 If the person sending a flame-o-gram at least had the grace to send it privately, then have the grace to keep it private yourself.
 If you feel you are being unfairly treated by another developer, and it is causing you anguish, bring the matter up with core rather than taking it public. Core will do its best to play peace makers and get things back to sanity.
 In cases where the dispute involves a change to the codebase and the participants do not appear to be reaching an amicable agreement, core may appoint a mutually-agreeable third party to resolve the dispute.
 All parties involved must then agree to be bound by the decision reached by this third party.
 . Respect all code freezes and read the `committers` and `developers` mailing list on a timely basis so you know when a code freeze is in effect.
-+ 
++
 Committing unapproved changes during a code freeze is a really big mistake and committers are expected to keep up-to-date on what is going on before jumping in after a long absence and committing 10 megabytes worth of accumulated stuff.
 People who abuse this on a regular basis will have their commit privileges suspended until they get back from the FreeBSD Happy Reeducation Camp we run in Greenland.
 . When in doubt on any procedure, ask first!
-+ 
++
 Many mistakes are made because someone is in a hurry and just assumes they know the right way of doing something.
 If you have not done it before, chances are good that you do not actually know the way we do things and really need to ask first or you are going to completely embarrass yourself in public.
 There is no shame in asking "how in the heck do I do this?" We already know you are an intelligent person; otherwise, you would not be a committer.
 . Test your changes before committing them.
-+ 
++
 This may sound obvious, but if it really were so obvious then we probably would not see so many cases of people clearly not doing this.
 If your changes are to the kernel, make sure you can still compile both GENERIC and LINT.
 If your changes are anywhere else, make sure you can still make world.
 If your changes are to a branch, make sure your testing occurs with a machine which is running that code.
 If you have a change which also may break another architecture, be sure and test on all supported architectures.
 Please refer to the https://www.FreeBSD.org/internal/[FreeBSD Internal Page] for a list of available resources.
 As other architectures are added to the FreeBSD supported platforms list, the appropriate shared testing resources will be made available.
 . Do not commit to contributed software without _explicit_ approval from the respective maintainers.
-+ 
++
 Contributed software is anything under the [.filename]#src/contrib#, [.filename]#src/crypto#, or [.filename]#src/sys/contrib# trees.
-+ 
++
 The trees mentioned above are for contributed software usually imported onto a vendor branch.
 Committing something there may cause unnecessary headaches when importing newer versions of the software.
 As a general consider sending patches upstream to the vendor.
 Patches may be committed to FreeBSD first with permission of the maintainer.
-+ 
++
 Reasons for modifying upstream software range from wanting strict control over a tightly coupled dependency to lack of portability in the canonical repository's distribution of their code.
 Regardless of the reason, effort to minimize the maintenance burden of fork is helpful to fellow maintainers.
 Avoid committing trivial or cosmetic changes to files since it makes every merge thereafter more difficult: such patches need to be manually re-verified every import.
-+ 
++
 If a particular piece of software lacks a maintainer, you are encouraged to take up ownership.
 If you are unsure of the current maintainership email {freebsd-arch} and ask.
 
 === Policy on Multiple Architectures
 
 FreeBSD has added several new architecture ports during recent release cycles and is truly no longer an i386(TM) centric operating system.
 In an effort to make it easier to keep FreeBSD portable across the platforms we support, core has developed this mandate:
 
 [.blockquote]
 Our 32-bit reference platform is i386, and our 64-bit reference platform is amd64.
 Major design work (including major API and ABI changes) must prove itself on at least one 32-bit and at least one 64-bit platform, preferably the primary reference platforms, before it may be committed to the source tree.
 
 The i386 and amd64 platforms were chosen due to being more readily available to developers and as representatives of more diverse processor and system designs - big versus little endian, register file versus register stack, different DMA and cache implementations, hardware page tables versus software TLB management etc.
 
 We will continue to re-evaluate this policy as cost and availability of the 64-bit platforms change.
 
 Developers should also be aware of our Tier Policy for the long term support of hardware architectures.
 The rules here are intended to provide guidance during the development process, and are distinct from the requirements for features and architectures listed in that section.
 The Tier rules for feature support on architectures at release-time are more strict than the rules for changes during the development process.
 
 === Other Suggestions
 
 When committing documentation changes, use a spell checker before committing.
 For all XML docs, verify that the formatting directives are correct by running `make lint` and package:textproc/igor[].
 
 For manual pages, run package:sysutils/manck[] and package:textproc/igor[] over the manual page to verify all of the cross references and file references are correct and that the man page has all of the appropriate `MLINKS` installed.
 
 Do not mix style fixes with new functionality.
 A style fix is any change which does not modify the functionality of the code.
 Mixing the changes obfuscates the functionality change when asking for differences between revisions, which can hide any new bugs.
 Do not include whitespace changes with content changes in commits to [.filename]#doc/#.
 The extra clutter in the diffs makes the translators' job much more difficult.
 Instead, make any style or whitespace changes in separate commits that are clearly labeled as such in the commit message.
 
 === Deprecating Features
 
 When it is necessary to remove functionality from software in the base system, follow these guidelines whenever possible:
 
 . Mention is made in the manual page and possibly the release notes that the option, utility, or interface is deprecated. Use of the deprecated feature generates a warning.
 . The option, utility, or interface is preserved until the next major (point zero) release.
 . The option, utility, or interface is removed and no longer documented. It is now obsolete. It is also generally a good idea to note its removal in the release notes.
 
 === Privacy and Confidentiality
 
 . Most FreeBSD business is done in public.
-+ 
++
 FreeBSD is an _open_ project.
 Which means that not only can anyone use the source code, but that most of the development process is open to public scrutiny.
 . Certain sensitive matters must remain private or held under embargo.
-+ 
++
 There unfortunately cannot be complete transparency.
 As a FreeBSD developer you will have a certain degree of privileged access to information.
 Consequently you are expected to respect certain requirements for confidentiality.
 Sometimes the need for confidentiality comes from external collaborators or has a specific time limit.
 Mostly though, it is a matter of not releasing private communications.
 . The Security Officer has sole control over the release of security advisories.
-+ 
++
 Where there are security problems that affect many different operating systems, FreeBSD frequently depends on early access to be able to prepare advisories for coordinated release.
 Unless FreeBSD developers can be trusted to maintain security, such early access will not be made available.
 The Security Officer is responsible for controlling pre-release access to information about vulnerabilities, and for timing the release of all advisories.
 He may request help under condition of confidentiality from any developer with relevant knowledge to prepare security fixes.
 . Communications with Core are kept confidential for as long as necessary.
-+ 
++
 Communications to core will initially be treated as confidential.
 Eventually however, most of Core's business will be summarized into the monthly or quarterly core reports.
 Care will be taken to avoid publicising any sensitive details.
 Records of some particularly sensitive subjects may not be reported on at all and will be retained only in Core's private archives.
 . Non-disclosure Agreements may be required for access to certain commercially sensitive data.
-+ 
++
 Access to certain commercially sensitive data may only be available under a Non-Disclosure Agreement.
 The FreeBSD Foundation legal staff must be consulted before any binding agreements are entered into.
 . Private communications must not be made public without permission.
-+ 
++
 Beyond the specific requirements above there is a general expectation not to publish private communications between developers without the consent of all parties involved.
 Ask permission before forwarding a message onto a public mailing list, or posting it to a forum or website that can be accessed by other than the original correspondents.
 . Communications on project-only or restricted access channels must be kept private.
-+ 
++
 Similarly to personal communications, certain internal communications channels, including FreeBSD Committer only mailing lists and restricted access IRC channels are considered private communications.
 Permission is required to publish material from these sources.
 . Core may approve publication.
-+ 
++
 Where it is impractical to obtain permission due to the number of correspondents or where permission to publish is unreasonably withheld, Core may approve release of such private matters that merit more general publication.
 
 [[archs]]
 == Support for Multiple Architectures
 
 FreeBSD is a highly portable operating system intended to function on many different types of hardware architectures.
 Maintaining clean separation of Machine Dependent (MD) and Machine Independent (MI) code, as well as minimizing MD code, is an important part of our strategy to remain agile with regards to current hardware trends.
 Each new hardware architecture supported by FreeBSD adds substantially to the cost of code maintenance, toolchain support, and release engineering.
 It also dramatically increases the cost of effective testing of kernel changes.
 As such, there is strong motivation to differentiate between classes of support for various architectures while remaining strong in a few key architectures that are seen as the FreeBSD "target audience".
 
 === Statement of General Intent
 
 The FreeBSD Project targets "production quality commercial off-the-shelf (COTS) workstation, server, and high-end embedded systems".
 By retaining a focus on a narrow set of architectures of interest in these environments, the FreeBSD Project is able to maintain high levels of quality, stability, and performance, as well as minimize the load on various support teams on the project, such as the ports team, documentation team, security officer, and release engineering teams.
 Diversity in hardware support broadens the options for FreeBSD consumers by offering new features and usage opportunities, but these benefits must always be carefully considered in terms of the real-world maintenance cost associated with additional platform support.
 
 The FreeBSD Project differentiates platform targets into four tiers.
 Each tier includes a list of guarantees consumers may rely on as well as obligations by the Project and developers to fulfill those guarantees.
 These lists define the minimum guarantees for each tier.
 The Project and developers may provide additional levels of support beyond the minimum guarantees for a given tier, but such additional support is not guaranteed.
 Each platform target is assigned to a specific tier for each stable branch.
 As a result, a platform target might be assigned to different tiers on concurrent stable branches.
 
 === Platform Targets
 
 Support for a hardware platform consists of two components: kernel support and userland Application Binary Interfaces (ABIs).
 Kernel platform support includes things needed to run a FreeBSD kernel on a hardware platform such as machine-dependent virtual memory management and device drivers.
 A userland ABI specifies an interface for user processes to interact with a FreeBSD kernel and base system libraries.
 A userland ABI includes system call interfaces, the layout and semantics of public data structures, and the layout and semantics of arguments passed to subroutines.
 Some components of an ABI may be defined by specifications such as the layout of C++ exception objects or calling conventions for C functions.
 
 A FreeBSD kernel also uses an ABI (sometimes referred to as the Kernel Binary Interface (KBI)) which includes the semantics and layouts of public data structures and the layout and semantics of arguments to public functions within the kernel itself.
 
 A FreeBSD kernel may support multiple userland ABIs.
 For example, FreeBSD's amd64 kernel supports FreeBSD amd64 and i386 userland ABIs as well as Linux x86_64 and i386 userland ABIs.
 A FreeBSD kernel should support a "native" ABI as the default ABI.
 The native "ABI" generally shares certain properties with the kernel ABI such as the C calling convention, sizes of basic types, etc.
 
 Tiers are defined for both kernels and userland ABIs. In the common case, a platform's kernel and FreeBSD ABIs are assigned to the same tier.
 
 === Tier 1: Fully-Supported Architectures
 
 Tier 1 platforms are the most mature FreeBSD platforms.
 They are supported by the security officer, release engineering, and port management teams.
 Tier 1 architectures are expected to be Production Quality with respect to all aspects of the FreeBSD operating system, including installation and development environments.
 
 The FreeBSD Project provides the following guarantees to consumers of Tier 1 platforms:
 
 * Official FreeBSD release images will be provided by the release engineering team.
 * Binary updates and source patches for Security Advisories and Errata Notices will be provided for supported releases.
 * Source patches for Security Advisories will be provided for supported branches.
 * Binary updates and source patches for cross-platform Security Advisories will typically be provided at the time of the announcement.
 * Changes to userland ABIs will generally include compatibility shims to ensure correct operation of binaries compiled against any stable branch where the platform is Tier 1. These shims might not be enabled in the default install. If compatibility shims are not provided for an ABI change, the lack of shims will be clearly documented in the release notes.
 * Changes to certain portions of the kernel ABI will include compatibility shims to ensure correct operation of kernel modules compiled against the oldest supported release on the branch. Note that not all parts of the kernel ABI are protected.
 * Official binary packages for third party software will be provided by the ports team. For embedded architectures, these packages may be cross-built from a different architecture.
 * Most relevant ports should either build or have the appropriate filters to prevent inappropriate ones from building.
 * New features which are not inherently platform-specific will be fully functional on all Tier 1 architectures.
 * Features and compatibility shims used by binaries compiled against older stable branches may be removed in newer major versions. Such removals will be clearly documented in the release notes.
 * Tier 1 platforms should be fully documented. Basic operations will be documented in the FreeBSD Handbook.
 * Tier 1 platforms will be included in the source tree.
 * Tier 1 platforms should be self-hosting either via the in-tree toolchain or an external toolchain. If an external toolchain is required, official binary packages for an external toolchain will be provided.
 
 To maintain maturity of Tier 1 platforms, the FreeBSD Project will maintain the following resources to support development:
 
 * Build and test automation support either in the FreeBSD.org cluster or some other location easily available for all developers. Embedded platforms may substitute an emulator available in the FreeBSD.org cluster for actual hardware.
 * Inclusion in the `make universe` and `make tinderbox` targets.
 * Dedicated hardware in one of the FreeBSD clusters for package building (either natively or via qemu-user).
 
 Collectively, developers are required to provide the following to maintain the Tier 1 status of a platform:
 
 * Changes to the source tree should not knowingly break the build of a Tier 1 platform.
 * Tier 1 architectures must have a mature, healthy ecosystem of users and active developers.
 * Developers should be able to build packages on commonly available, non-embedded Tier 1 systems. This can mean either native builds if non-embedded systems are commonly available for the platform in question, or it can mean cross-builds hosted on some other Tier 1 architecture.
 * Changes cannot break the userland ABI. If an ABI change is required, ABI compatibility for existing binaries should be provided via use of symbol versioning or shared library version bumps.
 * Changes merged to stable branches cannot break the protected portions of the kernel ABI. If a kernel ABI change is required, the change should be modified to preserve functionality of existing kernel modules.
 
 === Tier 2: Developmental and Niche Architectures
 
 Tier 2 platforms are functional, but less mature FreeBSD platforms.
 They are not supported by the security officer, release engineering, and port management teams.
 
 Tier 2 platforms may be Tier 1 platform candidates that are still under active development.
 Architectures reaching end of life may also be moved from Tier 1 status to Tier 2 status as the availability of resources to continue to maintain the system in a Production Quality state diminishes.
 Well-supported niche architectures may also be Tier 2.
 
 The FreeBSD Project provides the following guarantees to consumers of Tier 2 platforms:
 
 * The ports infrastructure should include basic support for Tier 2 architectures sufficient to support building ports and packages. This includes support for basic packages such as ports-mgmt/pkg, but there is no guarantee that arbitrary ports will be buildable or functional.
 * New features which are not inherently platform-specific should be feasible on all Tier 2 architectures if not implemented.
 * Tier 2 platforms will be included in the source tree.
 * Tier 2 platforms should be self-hosting either via the in-tree toolchain or an external toolchain. If an external toolchain is required, official binary packages for an external toolchain will be provided.
 * Tier 2 platforms should provide functional kernels and userlands even if an official release distribution is not provided.
 
 To maintain maturity of Tier 2 platforms, the FreeBSD Project will maintain the following resources to support development:
 
 * Inclusion in the `make universe` and `make tinderbox` targets.
 
 Collectively, developers are required to provide the following to maintain the Tier 2 status of a platform:
 
 * Changes to the source tree should not knowingly break the build of a Tier 2 platform.
 * Tier 2 architectures must have an active ecosystem of users and developers.
 * While changes are permitted to break the userland ABI, the ABI should not be broken gratuitously. Significant userland ABI changes should be restricted to major versions.
 * New features that are not yet implemented on Tier 2 architectures should provide a means of disabling them on those architectures.
 
 === Tier 3: Experimental Architectures
 
 Tier 3 platforms have at least partial FreeBSD support.
 They are _not_ supported by the security officer, release engineering, and port management teams.
 
 Tier 3 platforms are architectures in the early stages of development, for non-mainstream hardware platforms, or which are considered legacy systems unlikely to see broad future use.
 Initial support for Tier 3 platforms may exist in a separate repository rather than the main source repository.
 
 The FreeBSD Project provides no guarantees to consumers of Tier 3 platforms and is not committed to maintaining resources to support development.
 Tier 3 platforms may not always be buildable, nor are any kernel or userland ABIs considered stable.
 
 === Tier 4: Unsupported Architectures
 
 Tier 4 platforms are not supported in any form by the project.
 
 All systems not otherwise classified are Tier 4 systems.
 When a platform transitions to Tier 4, all support for the platform is removed from the source and ports trees.
 Note that ports support should remain as long as the platform is supported in a branch supported by ports.
 
 === Policy on Changing the Tier of an Architecture
 
 Systems may only be moved from one tier to another by approval of the FreeBSD Core Team, which shall make that decision in collaboration with the Security Officer, Release Engineering, and ports management teams.
 For a platform to be promoted to a higher tier, any missing support guarantees must be satisfied before the promotion is completed.
 
 [[ports]]
 == Ports Specific FAQ
 
 [[ports-qa-adding]]
 === Adding a New Port
 
 [[ports-qa-add-new]]
 ==== How do I add a new port?
 
 First, please read the section about repository copies.
 
 The easiest way to add a new port is the `addport` script located in the [.filename]#ports/Tools/scripts# directory.
 It adds a port from the directory specified, determining the category automatically from the port [.filename]#Makefile#.
 It also adds an entry to the port's category [.filename]#Makefile#.
 It was written by `{mharo}`, `{will}`, and `{garga}`.
 When sending questions about this script to the {freebsd-ports}, please also CC `{crees}`, the current maintainer.
 
 [[ports-qa-add-new-extra]]
 ==== Any other things I need to know when I add a new port?
 
 Check the port, preferably to make sure it compiles and packages correctly.
 
 The link:{porters-handbook}testing[Porters Handbook's Testing Chapter] contains more detailed instructions.
 See the link:{porters-handbook}testing#testing-portclippy[Portclippy / Portfmt] and the link:{porters-handbook}testing#testing-poudriere[Poudriere] sections.
 
 You do not necessarily have to eliminate all warnings but make sure you have fixed the simple ones.
 
 If the port came from a submitter who has not contributed to the Project before, add that person's name to the link:{contributors}#contrib-additional[Additional Contributors] section of the FreeBSD Contributors List.
 
 Close the PR if the port came in as a PR.
 To close a PR, change the state to `Issue Resolved` and the resolution as `Fixed`.
 
 [NOTE]
 ====
 If for some reason using link:{porters-handbook}testing#testing-poudriere[Poudriere] to test the new port is not possible, the bare minimum of testing includes this sequence:
 
 [source,shell]
 ....
 # make install
 # make package
 # make deinstall
 # pkg add package you built above
 # make deinstall
 # make reinstall
 # make package
 ....
 
 Note that poudriere is the reference for package building, it the port does not build in poudriere, it will be removed.
 ====
 
 [[ports-qa-removing]]
 === Removing an Existing Port
 
 [[ports-qa-remove-one]]
 ==== How do I remove an existing port?
 
 First, please read the section about repository copies. Before you remove the port, you have to verify there are no other ports depending on it.
 
 * Make sure there is no dependency on the port in the ports collection:
 ** The port's PKGNAME appears in exactly one line in a recent INDEX file.
 ** No other ports contains any reference to the port's directory or PKGNAME in their Makefiles
 +
 [TIP]
 ====
 When using Git, consider using man:git-grep[1], it is much faster than `grep -r`.
 ====
 +
 * Then, remove the port:
 +
 [.procedure]
 ====
 * Remove the port's files and directory with `git rm`.
 * Remove the `SUBDIR` listing of the port in the parent directory [.filename]#Makefile#.
 * Add an entry to [.filename]#ports/MOVED#.
 * Search for entries in [.filename]#ports/security/vuxml/vuln.xml# and adjust them accordingly. In particular, check for previous packages with the new name which version could include the new port.
 * Remove the port from [.filename]#ports/LEGAL# if it is there.
 ====
 
 Alternatively, you can use the rmport script, from [.filename]#ports/Tools/scripts#.
 This script was written by {vd}.
 When sending questions about this script to the {freebsd-ports}, please also CC {crees}, the current maintainer.
 
 [[ports-qa-move-port]]
 === How do I move a port to a new location?
 
 [.procedure]
 ====
 . Perform a thorough check of the ports collection for any dependencies on the old port location/name, and update them. Running `grep` on [.filename]#INDEX# is not enough because some ports have dependencies enabled by compile-time options. A full man:git-grep[1] of the ports collection is recommended.
 . Remove the `SUBDIR` entry from the old category Makefile and add a `SUBDIR` entry to the new category Makefile.
 . Add an entry to [.filename]#ports/MOVED#.
 . Move the port with `git mv`.
 . Commit the changes.
 ====
 
 [[ports-qa-copy-port]]
 === How do I copy a port to a new location?
 
 [.procedure]
 ====
 . Copy port with `cp -R old-cat/old-port new-cat/new-port`.
 . Add the new port to the [.filename]#new-cat/Makefile#.
 . Change stuff in [.filename]#new-cat/new-port#.
 . Commit the changes.
 ====
 
 [[ports-qa-freeze]]
 === Ports Freeze
 
 [[ports-qa-freeze-what]]
 ==== What is a “ports freeze”?
 
 A “ports freeze” was a restricted state the ports tree was put in before a release.
 It was used to ensure a higher quality for the packages shipped with a release.
 It usually lasted a couple of weeks.
 During that time, build problems were fixed, and the release packages were built.
 This practice is no longer used, as the packages for the releases are built from the current stable, quarterly branch.
 
 For more information on how to merge commits to the quarterly branch, see <<ports-qa-misc-request-mfh>>.
 
 [[ports-qa-quarterly]]
 === Quarterly Branches
 
 [[ports-qa-misc-request-mfh]]
 ==== What is the procedure to request authorization for merging a commit to the quarterly branch?
 
 As of November 30, 2020, there is no need to seek explicit approval to commit to the quarterly branch.
 
 [[ports-qa-misc-commit-mfh]]
 ==== What is the procedure for merging commits to the quarterly branch?
 
 Merging commits to the quarterly branch is very similar to MFC'ing a commit in the src repository, so basically:
 [source,shell]
 ....
 % git checkout 2021Q2
 % git cherry-pick -x $HASH
 (verify everything is OK, for example by doing a build test)
 % git push
 ....
 
 where '$HASH' is the hash of the commit you want to copy over to the quarterly branch.
 The -x parameter ensures the hash '$HASH' of the main branch is included in the new commit message of the quarterly branch.
 
 [[ports-qa-new-category]]
 === Creating a New Category
 
 [[ports-qa-new-category-how]]
 ==== What is the procedure for creating a new category?
 
 Please see link:{porters-handbook}#proposing-categories[Proposing a New Category] in the Porter's Handbook.
 Once that procedure has been followed and the PR has been assigned to the {portmgr}, it is their decision whether or not to approve it.
 If they do, it is their responsibility to:
 
 [.procedure]
 ====
 . Perform any needed moves. (This only applies to physical categories.)
 . Update the `VALID_CATEGORIES` definition in [.filename]#ports/Mk/bsd.port.mk#.
 . Assign the PR back to you.
 ====
 
 [[ports-qa-new-category-physical]]
 ==== What do I need to do to implement a new physical category?
 
 [.procedure]
 ====
 . Upgrade each moved port's [.filename]#Makefile#. Do not connect the new category to the build yet.
 +
 To do this, you will need to:
 +
 [.procedure]
 ======
 . Change the port's `CATEGORIES` (this was the point of the exercise, remember?) The new category is listed first. This will help to ensure that the PKGORIGIN is correct.
 . Run a `make describe`. Since the top-level `make index` that you will be running in a few steps is an iteration of `make describe` over the entire ports hierarchy, catching any errors here will save you having to re-run that step later on.
 . If you want to be really thorough, now might be a good time to run man:portlint[1].
 ======
 +
 . Check that the ``PKGORIGIN``s are correct. The ports system uses each port's `CATEGORIES` entry to create its `PKGORIGIN`, which is used to connect installed packages to the port directory they were built from. If this entry is wrong, common port tools like man:pkg_version[1] and man:portupgrade[1] fail.
 +
 To do this, use the [.filename]#chkorigin.sh# tool: `env PORTSDIR=/path/to/ports sh -e /path/to/ports/Tools/scripts/chkorigin.sh`. This will check every port in the ports tree, even those not connected to the build, so you can run it directly after the move operation. Hint: do not forget to look at the ``PKGORIGIN``s of any slave ports of the ports you just moved!
 . On your own local system, test the proposed changes: first, comment out the SUBDIR entries in the old ports' categories' [.filename]##Makefile##s; then enable building the new category in [.filename]#ports/Makefile#. Run make checksubdirs in the affected category directories to check the SUBDIR entries. Next, in the [.filename]#ports/# directory, run make index. This can take over 40 minutes on even modern systems; however, it is a necessary step to prevent problems for other people.
 . Once this is done, you can commit the updated [.filename]#ports/Makefile# to connect the new category to the build and also commit the [.filename]#Makefile# changes for the old category or categories.
 . Add appropriate entries to [.filename]#ports/MOVED#.
 . Update the documentation by modifying:
 ** the link:{porters-handbook}#PORTING-CATEGORIES[list of categories] in the Porter's Handbook
 +
 . Only once all the above have been done, and no one is any longer reporting problems with the new ports, should the old ports be deleted from their previous locations in the repository.
 ====
 
 ==== What do I need to do to implement a new virtual category?
 
 This is much simpler than a physical category. Only a few modifications are needed:
 
 * the link:{porters-handbook}#PORTING-CATEGORIES[list of categories] in the Porter's Handbook
 
 [[ports-qa-misc-questions]]
 === Miscellaneous Questions
 
 [[ports-qa-misc-blanket-approval]]
 ==== Are there changes that can be committed without asking the maintainer for approval?
 
 Blanket approval for most ports applies to these types of fixes:
 
 * Most infrastructure changes to a port (that is, modernizing, but not changing the functionality). For example, the blanket covers converting to new `USES` macros, enabling verbose builds, and switching to new ports system syntaxes.
 * Trivial and _tested_ build and runtime fixes.
 * Documentations or metadata changes to ports, like [.filename]#pkg-descr# or `COMMENT`.
 
 [IMPORTANT]
 ====
 Exceptions to this are anything maintained by the {portmgr}, or the {security-officer}.
 No unauthorized commits may ever be made to ports maintained by those groups.
 ====
 
 [[ports-qa-misc-correctly-building]]
 ==== How do I know if my port is building correctly or not?
 
 The packages are built multiple times each week.
 If a port fails, the maintainer will receive an email from `pkg-fallout@FreeBSD.org`.
 
 Reports for all the package builds (official, experimental, and non-regression) are aggregated at link:pkg-status.FreeBSD.org[pkg-status.FreeBSD.org].
 
 [[ports-qa-misc-INDEX]]
 ==== I added a new port. Do I need to add it to the [.filename]#INDEX#?
 
 No. The file can either be generated by running `make index`, or a pre-generated version can be downloaded with `make fetchindex`.
 
 [[ports-qa-misc-no-touch]]
 ==== Are there any other files I am not allowed to touch?
 
 Any file directly under [.filename]#ports/#, or any file under a subdirectory that starts with an uppercase letter ([.filename]#Mk/#, [.filename]#Tools/#, etc.).
 In particular, the {portmgr} is very protective of [.filename]#ports/Mk/bsd.port*.mk# so do not commit changes to those files unless you want to face their wrath.
 
 [[ports-qa-misc-updated-distfile]]
 ==== What is the proper procedure for updating the checksum for a port distfile when the file changes without a version change?
 
 When the checksum for a distribution file is updated due to the author updating the file without changing the port revision, the commit message includes a summary of the relevant diffs between the original and new distfile to ensure that the distfile has not been corrupted or maliciously altered.
 If the current version of the port has been in the ports tree for a while, a copy of the old distfile will usually be available on the ftp servers; otherwise the author or maintainer should be contacted to find out why the distfile has changed.
 
 [[ports-exp-run]]
 ==== How can an experimental test build of the ports tree (exp-run) be requested?
 
 An exp-run must be completed before patches with a significant ports impact are committed.
 The patch can be against the ports tree or the base system.
 
 Full package builds will be done with the patches provided by the submitter, and the submitter is required to fix detected problems _(fallout)_ before commit.
 
 [.procedure]
 ====
 . Go to the link:https://bugs.freebsd.org/submit[Bugzilla new PR page].
 . Select the product your patch is about.
 . Fill in the bug report as normal. Remember to attach the patch.
 . If at the top it says “Show Advanced Fields” click on it. It will now say “Hide Advanced Fields”. Many new fields will be available. If it already says “Hide Advanced Fields”, no need to do anything.
 . In the “Flags” section, set the “exp-run” one to `?`. As for all other fields, hovering the mouse over any field shows more details.
 . Submit. Wait for the build to run.
 . {portmgr} will reply with a possible fallout.
 . Depending on the fallout:
 ** If there is no fallout, the procedure stops here, and the change can be committed, pending any other approval required.
 ... If there is fallout, it _must_ be fixed, either by fixing the ports directly in the ports tree, or adding to the submitted patch.
 ... When this is done, go back to step 6 saying the fallout was fixed and wait for the exp-run to be run again. Repeat as long as there are broken ports.
 ====
 
 [[non-committers]]
 == Issues Specific to Developers Who Are Not Committers
 
 A few people who have access to the FreeBSD machines do not have commit bits.
 Almost all of this document will apply to these developers as well (except things specific to commits and the mailing list memberships that go with them). 
 In particular, we recommend that you read:
 
 * <<admin>>
 * <<conventions-everyone>>
 +
 [NOTE]
 ====
 Get your mentor to add you to the "Additional Contributors" ([.filename]#~/documentation/content/en/articles/contributors/contrib-additional.adoc#), if you are not already listed there.
 ====
 * <<developer.relations>>
 * <<ssh.guide>>
 * <<rules>>
 
 [[google-analytics]]
 == Information About Google Analytics
 
 As of December 12, 2012, Google Analytics was enabled on the FreeBSD Project website to collect anonymized usage statistics regarding usage of the site. 
 The information collected is valuable to the FreeBSD Documentation Project, to identify various problems on the FreeBSD website.
 
 [[google-analytics-policy]]
 === Google Analytics General Policy
 
 The FreeBSD Project takes visitor privacy very seriously.
 As such, the FreeBSD Project website honors the "Do Not Track" header _before_ fetching the tracking code from Google.
 For more information, please see the https://www.FreeBSD.org/privacy/[FreeBSD Privacy Policy].
 
 Google Analytics access is _not_ arbitrarily allowed - access must be requested, voted on by the `{doceng}`, and explicitly granted.
 
 Requests for Google Analytics data must include a specific purpose.
 For example, a valid reason for requesting access would be "to see the most frequently used web browsers when viewing FreeBSD web pages to ensure page rendering speeds are acceptable."
 
 Conversely, "to see what web browsers are most frequently used" (without stating __why__) would be rejected.
 
 All requests must include the timeframe for which the data would be required.
 For example, it must be explicitly stated if the requested data would be needed for a timeframe covering a span of 3 weeks, or if the request would be one-time only.
 
 Any request for Google Analytics data without a clear, reasonable reason beneficial to the FreeBSD Project will be rejected.
 
 [[google-analytics-data]]
 === Data Available Through Google Analytics
 
 A few examples of the types of Google Analytics data available include:
 
 * Commonly used web browsers
 * Page load times
 * Site access by language
 
 [[misc]]
 == Miscellaneous Questions
 
 === Are there changes that can be committed without asking the maintainer for approval?
 
 Blanket approval for most ports applies to these types of fixes:
 
 * Most infrastructure changes to a port (that is, modernizing, but not changing the functionality). For example, the blanket covers converting to new `USES` macros, enabling verbose builds, and switching to new ports system syntaxes.
 * Trivial and _tested_ build and runtime fixes.
 * Documentations or metadata changes to ports, like [.filename]#pkg-descr# or `COMMENT`.
 
 === How do I access people.FreeBSD.org to put up personal or project information?
 
 `people.FreeBSD.org` is the same as `freefall.FreeBSD.org`.
 Just create a [.filename]#public_html# directory. Anything you place in that directory will automatically be visible under https://people.FreeBSD.org/[https://people.FreeBSD.org/].
 
 === Where are the mailing list archives stored?
 
 The mailing lists are archived under [.filename]#/local/mail# on `freefall.FreeBSD.org`.
 
 === I would like to mentor a new committer. What process do I need to follow?
 
 See the https://www.freebsd.org/internal/new-account/[New Account Creation Procedure] document on the internal pages.
 
 [[benefits]]
 == Benefits and Perks for FreeBSD Committers
 
 [[benefits-recognition]]
 === Recognition
 
 Recognition as a competent software engineer is the longest lasting value.
 In addition, getting a chance to work with some of the best people that every engineer would dream of meeting is a great perk!
 
 [[benefits-freebsdmall]]
 === FreeBSD Mall
 
 FreeBSD committers can get a free 4-CD or DVD set at conferences from http://www.freebsdmall.com[FreeBSD Mall, Inc.].
 
 [[benefits-irc]]
 === IRC
 
 In addition, developers may request a cloaked hostmask for their account on the Freenode IRC network in the form of `freebsd/developer/<freefall username>` or `freebsd/developer/<FreeNode account>`.
 To request a cloak, send an email to `{irc-email}` with your requested hostmask and NickServ account name.
 See the https://wiki.freebsd.org/IRC/Cloaks[IRC Cloaks] wiki page for more details.
 
 [[benefits-gandi]]
 === `Gandi.net`
 
 https://gandi.net[Gandi] provides website hosting, cloud computing, domain registration, and X.509 certificate services.
 
 Gandi offers an E-rate discount to all FreeBSD developers.
 In order to streamline the process of getting the discount first set up a Gandi account, fill in the billing information and select the currency.
 Then send an mail to mailto:non-profit@gandi.net[non-profit@gandi.net] using your `@freebsd.org` mail address, and indicate your Gandi handle.
 
 [[benefits-rsync]]
 === `rsync.net`
 
 https://rsync.net[rsync.net] provides cloud storage for offsite backup that is optimized for UNIX users. Their service runs entirely on FreeBSD and ZFS.
 
 rsync.net offers a free-forever 500 GB account to FreeBSD developers. Simply sign up at https://www.rsync.net/freebsd.html[https://www.rsync.net/freebsd.html] using your `@freebsd.org` address to receive this free account.
diff --git a/documentation/content/en/articles/contributing/_index.adoc b/documentation/content/en/articles/contributing/_index.adoc
index 2f4c6e20a5..4692420631 100644
--- a/documentation/content/en/articles/contributing/_index.adoc
+++ b/documentation/content/en/articles/contributing/_index.adoc
@@ -1,587 +1,587 @@
 ---
 title: Contributing to FreeBSD
 authors:
   - author: Jordan Hubbard
   - author: Sam Lawrance
   - author: Mark Linimon
 description: How to contribute to the FreeBSD Project
 trademarks: ["freebsd", "ieee", "general"]
 weight: 15
 tags: ["Contributing", "FreeBSD", "Non-Programmer Tasks", "Programmer Tasks"]
 ---
 
 = Contributing to FreeBSD
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 [.abstract-title]
 Abstract
 
 This article describes the different ways in which an individual or organization may contribute to the FreeBSD Project.
 
 '''
 
 toc::[]
 
 So you want to contribute to FreeBSD? That is great! FreeBSD _relies_ on the contributions of its user base to survive.
 Your contributions are not only appreciated, they are vital to FreeBSD's continued growth.
 
 A large and growing number of international contributors, of greatly varying ages and areas of technical expertise, develop FreeBSD.
 There is always more work to be done than there are people available to do it, and more help is always appreciated.
 
 As a volunteer, what you do is limited only by what you want to do.
 However, we do ask that you are aware of what other members of the FreeBSD community will expect of you.
 You may want to take this into account before deciding to volunteer.
 
 The FreeBSD project is responsible for an entire operating system environment, rather than just a kernel or a few scattered utilities.
 As such, our [.filename]#TODO# lists span a very wide range of tasks: from documentation, beta testing and presentation, to the system installer and highly specialized types of kernel development.
 People of any skill level, in almost any area, can almost certainly help the project.
 
 Commercial entities engaged in FreeBSD-related enterprises are also encouraged to contact us.
 Do you need a special extension to make your product work? You will find us receptive to your requests, given that they are not too outlandish.
 Are you working on a value-added product? Please let us know! We may be able to work cooperatively on some aspect of it.
 The free software world is challenging many existing assumptions about how software is developed, sold, and maintained, and we urge you to at least give it a second look.
 
 [[contrib-what]]
 == What Is Needed
 
 The following list of tasks and sub-projects represents something of an amalgam of various [.filename]#TODO# lists and user requests.
 
 [[non-programmer-tasks]]
 === Ongoing Non-Programmer Tasks
 
 Many people who are involved in FreeBSD are not programmers.
 The Project includes documentation writers, Web designers, and support people.
 All that these people need to contribute is an investment of time and a willingness to learn.
 
 . Read through the FAQ and Handbook periodically. If anything is poorly explained, ambiguous, out of date or incorrect, let us know. Even better, send us a fix (Docbook is not difficult to learn, but there is no objection to ASCII submissions).
 . Help translate FreeBSD documentation into your native language. If documentation already exists for your language, you can help translate additional documents or verify that the translations are up-to-date and correct. First take a look at the link:{fdp-primer}#translations[Translations FAQ] in the FreeBSD Documentation Project Primer. You are not committing yourself to translating every single FreeBSD document by doing this - as a volunteer, you can do as much or as little translation as you desire. Once someone begins translating, others almost always join the effort. If you only have the time or energy to translate one part of the documentation, please translate the installation instructions.
 . Read the {freebsd-questions} occasionally (or even regularly). It can be very satisfying to share your expertise and help people solve their problems; sometimes you may even learn something new yourself! These forums can also be a source of ideas for things to improve upon. 
 
 [[ongoing-programmer-tasks]]
 === Ongoing Programmer Tasks
 
 Most of the tasks listed here may require a considerable investment of time, an in-depth knowledge of the FreeBSD kernel, or both.
 However, there are also many useful tasks which are suitable for "weekend hackers".
 
 . If you run FreeBSD-CURRENT and have a good Internet connection, there is a machine `current.FreeBSD.org` which builds a full release once a day-every now and again, try to install the latest release from it and report any failures in the process.
 . Read the {freebsd-bugs}. There may be a problem you can comment constructively on or with patches you can test. Or you could even try to fix one of the problems yourself.
 . If you know of any bug fixes which have been successfully applied to -CURRENT but have not been merged into -STABLE after a decent interval (normally a couple of weeks), send the committer a polite reminder.
 . Move contributed software to [.filename]#src/contrib# in the source tree.
 . Make sure code in [.filename]#src/contrib# is up to date.
 . Build the source tree (or just part of it) with extra warnings enabled and clean up the warnings. A list of build warnings can also be found from our https://ci.freebsd.org[CI] by selecting a build and checking "LLVM/Clang Warnings".
 . Fix warnings for ports which do deprecated things like using `gets()` or including [.filename]#malloc.h#.
 . If you have contributed any ports and you had to make FreeBSD-specific changes, send your patches back to the original authors (this will make your life easier when they bring out the next version).
 . Get copies of formal standards like POSIX(R). Compare FreeBSD's behavior to that required by the standard. If the behavior differs, particularly in subtle or obscure corners of the specification, send in a PR about it. If you are able, figure out how to fix it and include a patch in the PR. If you think the standard is wrong, ask the standards body to consider the question.
 . Suggest further tasks for this list!
 
 === Work through the PR Database
 
 The https://bugs.FreeBSD.org/search/[FreeBSD PR list] shows all the current active problem reports and requests for enhancement that have been submitted by FreeBSD users.
 The PR database includes both programmer and non-programmer tasks.
 Look through the open PRs, and see if anything there takes your interest.
 Some of these might be very simple tasks that just need an extra pair of eyes to look over them and confirm that the fix in the PR is a good one.
 Others might be much more complex, or might not even have a fix included at all.
 
 Start with the PRs that have not been assigned to anyone else.
 If a PR is assigned to someone else, but it looks like something you can handle, email the person it is assigned to and ask if you can work on it-they might already have a patch ready to be tested, or further ideas that you can discuss with them.
 
 === Ongoing Ports Tasks
 
 The Ports Collection is a perpetual work in progress.
 We want to provide our users with an easy to use, up to date, high quality repository of third party software.
 We need people to donate some of their time and effort to help us achieve this goal.
 
 Anyone can get involved, and there are lots of different ways to do so.
 Contributing to ports is an excellent way to help "give back" something to the project.
 Whether you are looking for an ongoing role, or a fun challenge for a rainy day, we would love to have your help!
 
 There are a number of easy ways you can contribute to keeping the ports tree up to date and in good working order:
 
 * Find some cool or useful software and link:{porters-handbook}[create a port] for it.
 * There are a large number of ports that have no maintainer. Become a maintainer and <<adopt-port>>.
 * If you have created or adopted a port, be aware of <<maintain-port>>.
 * When you are looking for a quick challenge you could <<fix-broken>>.
 
 === Pick one of the items from the Ideas page
 
 The https://wiki.freebsd.org/IdeasPage[FreeBSD list of projects and ideas for volunteers] is also available for people willing to contribute to the FreeBSD project.
 The list is being regularly updated and contains items for both programmers and non-programmers with information about each project.
 
 [[contrib-how]]
 == How to Contribute
 
 Contributions to the system generally fall into one or more of the following 5 categories:
 
 [[contrib-general]]
 === Bug Reports and General Commentary
 
 An idea or suggestion of _general_ technical interest should be mailed to the {freebsd-hackers}.
 Likewise, people with an interest in such things (and a tolerance for a _high_ volume of mail!) may subscribe to the {freebsd-hackers}.
 See link:{handbook}#eresources-mail[The FreeBSD Handbook] for more information about this and other mailing lists.
 
 If you find a bug or are submitting a specific change, please report it using the https://bugs.FreeBSD.org/submit/[bug submission form].
 Try to fill-in each field of the bug report.
 Unless they exceed 65KB, include any patches directly in the report.
 If the patch is suitable to be applied to the source tree put `[PATCH]` in the synopsis of the report.
 When including patches, _do not_ use cut-and-paste because cut-and-paste turns tabs into spaces and makes them unusable.
 When patches are a lot larger than 20KB, consider compressing them (eg. with man:gzip[1] or man:bzip2[1]) prior to uploading them.
 
 After filing a report, you should receive confirmation along with a tracking number.
 Keep this tracking number so that you can update us with details about the problem.
 
 See also link:{problem-reports}[this article] on how to write good problem reports.
 
 === Changes to the Documentation
 
 Changes to the documentation are overseen by the {freebsd-doc}.
 Please look at the link:{fdp-primer}[FreeBSD Documentation Project Primer] for complete instructions.
 Send submissions and changes (even small ones are welcome!) using the same method as any other bug report.
 
 === Changes to Existing Source Code
 
 An addition or change to the existing source code is a somewhat trickier affair and depends a lot on how far out of date you are with the current state of FreeBSD development.
 There is a special on-going release of FreeBSD known as "FreeBSD-CURRENT" which is made available in a variety of ways for the convenience of developers working actively on the system.
 See link:{handbook}#current-stable[The FreeBSD Handbook] for more information about getting and using FreeBSD-CURRENT.
 
 Working from older sources unfortunately means that your changes may sometimes be too obsolete or too divergent for easy re-integration into FreeBSD.
 Chances of this can be minimized somewhat by subscribing to the {freebsd-announce} and the {freebsd-current} lists, where discussions on the current state of the system take place.
 
 Assuming that you can manage to secure fairly up-to-date sources to base your changes on, the next step is to produce a set of diffs to send to the FreeBSD maintainers.
 This is done with the man:diff[1] command.
 
 The preferred man:diff[1] format for submitting patches is the unified output format generated by `diff -u`.
 
 [source,shell]
 ....
 % diff -u oldfile newfile
 ....
 
 or
 
 [source,shell]
 ....
 % diff -u -r -N olddir newdir
 ....
 
 would generate a set of unified diffs for the given source file or directory hierarchy.
 
 See man:diff[1] for more information.
 
 Once you have a set of diffs (which you may test with the man:patch[1] command), you should submit them for inclusion with FreeBSD as a bug report.
 _Do not_ just send the diffs to the {freebsd-hackers} or they will get lost! We greatly appreciate your submission (this is a volunteer project!); because we are busy, we may not be able to address it immediately, but it will remain in the PR database until we do.
 Indicate your submission by including `[PATCH]` in the synopsis of the report.
 
 If you feel it appropriate (e.g. you have added, deleted, or renamed files), bundle your changes into a `tar` file.
 Archives created with man:shar[1] are also welcome.
 
 If your change is of a potentially sensitive nature, such as if you are unsure of copyright issues governing its further distribution then you should send it to {core-email} directly rather than submitting as a bug report.
 The {core-email} reaches a much smaller group of people who do much of the day-to-day work on FreeBSD.
 Note that this group is also _very busy_ and so you should only send mail to them where it is truly necessary.
 
 Please refer to man:intro[9] and man:style[9] for some information on coding style.
 We would appreciate it if you were at least aware of this information before submitting code.
 
 === New Code or Major Value-Added Packages
 
 In the case of a significant contribution of a large body work, or the addition of an important new feature to FreeBSD, it becomes almost always necessary to either send changes as tar files or upload them to a web or FTP site for other people to access.
 If you do not have access to a web or FTP site, ask on an appropriate FreeBSD mailing list for someone to host the changes for you.
 
 When working with large amounts of code, the touchy subject of copyrights also invariably comes up.
 FreeBSD prefers free software licenses such as BSD or ISC.
 Copyleft licenses such as GPLv2 are sometimes permitted.
 The complete listing can be found on the link:https://www.FreeBSD.org/internal/software-license/[core team licensing policy] page.
 
 === Money or Hardware
 
 We are always very happy to accept donations to further the cause of the FreeBSD Project and, in a volunteer effort like ours, a little can go a long way! Donations of hardware are also very important to expanding our list of supported peripherals since we generally lack the funds to buy such items ourselves.
 
 [[donations]]
 ==== Donating Funds
 
 The https://www.freebsdfoundation.org[FreeBSD Foundation] is a non-profit, tax-exempt foundation established to further the goals of the FreeBSD Project. 
 As a 501(c)3 entity, the Foundation is generally exempt from US federal income tax as well as Colorado State income tax.
 Donations to a tax-exempt entity are often deductible from taxable federal income.
 
 Donations may be sent in check form to:
 
 [.address]
 ****
 The FreeBSD Foundation +
 P.O. Box 20247, +
 Boulder, +
 CO 80308 +
 USA
 ****
 
 The FreeBSD Foundation is also able to accept https://www.freebsdfoundation.org/donate/[online donations] through various payment options.
 
 More information about the FreeBSD Foundation can be found in https://people.FreeBSD.org/~jdp/foundation/announcement.html[The FreeBSD Foundation -- an Introduction].
 To contact the Foundation by email, write to mailto:info@FreeBSDFoundation.org[info@FreeBSDFoundation.org].
 
 ==== Donating Hardware
 
 The FreeBSD Project happily accepts donations of hardware that it can find good use for.
 If you are interested in donating hardware, please contact the link:https://www.FreeBSD.org/donations/[Donations Liaison Office].
 
 [[ports-contributing]]
 == Contributing to ports
 
 [[adopt-port]]
 === Adopting an unmaintained port
 
 ==== Choosing an unmaintained port
 
 Taking over maintainership of ports that are unmaintained is a great way to get involved.
 Unmaintained ports are only updated and fixed when somebody volunteers to work on them.
 There are a large number of unmaintained ports.
 It is a good idea to start with adopting a port that you use regularly.
 
 Unmaintained ports have their `MAINTAINER` set to `ports@FreeBSD.org`.
 A list of unmaintained ports and their current errors and problem reports can be seen at the http://portsmon.FreeBSD.org/portsconcordanceformaintainer.py?maintainer=ports%40FreeBSD.org[FreeBSD Ports Monitoring System].
 
 On https://portsfallout.com/fallout?port=&maintainer=ports%40FreeBSD.org[PortsFallout] can be seen a list of unmaintained ports with errors.
 
 Many unmaintained ports can have pending updates, this can be seen at the https://portscout.freebsd.org/ports@freebsd.org.html[FreeBSD Ports distfile scanner].
 
 Some ports affect a large number of others due to dependencies and slave port relationships.
 Generally, we want people to have some experience before they maintain such ports.
 
 You can find out whether or not a port has dependencies or slave ports by looking at a master index of ports called [.filename]#INDEX#.
 (The name of the file varies by release of FreeBSD; for instance, [.filename]#INDEX-8#.) Some ports have conditional dependencies that are not included in a default [.filename]#INDEX# build.
 We expect you to be able to recognize such ports by looking through other ports' [.filename]#Makefile#'s.
 
 [NOTE]
 ======
 The FreeBSD Ports Monitoring System (portsmon) is currently not working due to latest Python updates.
 ======
 
 ==== How to adopt the port
 
 First make sure you understand your <<maintain-port>>.
 Also read the link:{porters-handbook}[Porter's Handbook].
 _Please do not commit yourself to more than you feel you can comfortably handle._
 
 You may request maintainership of any unmaintained port as soon as you wish.
 Simply set `MAINTAINER` to your own email address and send a PR (Problem Report) with the change.
 If the port has build errors or needs updating, you may wish to include any other changes in the same PR.
 This will help because many committers are less willing to assign maintainership to someone who does not have a known track record with FreeBSD.
 Submitting PRs that fix build errors or update ports are the best ways to establish one.
 
 File your PR with category `ports` and class `change-request`.
 A committer will examine your PR, commit the changes, and finally close the PR.
 Sometimes this process can take a little while (committers are volunteers, too :).
 
 [[maintain-port]]
 === The challenge for port maintainers
 
 This section will give you an idea of why ports need to be maintained and outline the responsibilities of a port maintainer.
 
 [[why-maintenance]]
 ==== Why ports require maintenance
 
 Creating a port is a once-off task.
 Ensuring that a port is up to date and continues to build and run requires an ongoing maintenance effort.
 Maintainers are the people who dedicate some of their time to meeting these goals.
 
 The foremost reason ports need maintenance is to bring the latest and greatest in third party software to the FreeBSD community.
 An additional challenge is to keep individual ports working within the Ports Collection framework as it evolves.
 
 As a maintainer, you will need to manage the following challenges:
 
 * *New software versions and updates.* New versions and updates of existing ported software become available all the time, and these need to be incorporated into the Ports Collection in order to provide up-to-date software.
 
 * *Changes to dependencies.* If significant changes are made to the dependencies of your port, it may need to be updated so that it will continue to work correctly.
 
 * *Changes affecting dependent ports.* If other ports depend on a port that you maintain, changes to your port may require coordination with other maintainers.
 
 * *Interaction with other users, maintainers and developers.* Part of being a maintainer is taking on a support role. You are not expected to provide general support (but we welcome it if you choose to do so). What you should provide is a point of coordination for FreeBSD-specific issues regarding your ports.
 
 * *Bug hunting.* A port may be affected by bugs which are specific to FreeBSD. You will need to investigate, find, and fix these bugs when they are reported. Thoroughly testing a port to identify problems before they make their way into the Ports Collection is even better.
 
 * *Changes to ports infrastructure and policy.* Occasionally the systems that are used to build ports and packages are updated or a new recommendation affecting the infrastructure is made. You should be aware of these changes in case your ports are affected and require updating.
 
 * *Changes to the base system.* FreeBSD is under constant development. Changes to software, libraries, the kernel or even policy changes can cause flow-on change requirements to ports.
 
 ==== Maintainer responsibilities
 
 ===== Keep your ports up to date
 
 This section outlines the process to follow to keep your ports up to date.
 
 This is an overview.
 More information about upgrading a port is available in the link:{porters-handbook}[Porter's Handbook].
 
 [.procedure]
 ====
 . Watch for updates
-+ 
++
 Monitor the upstream vendor for new versions, updates and security fixes for the software.
 Announcement mailing lists or news web pages are useful for doing this.
 Sometimes users will contact you and ask when your port will be updated.
 If you are busy with other things or for any reason just cannot update it at the moment, ask if they will help you by submitting an update.
-+ 
++
 You may also receive automated email from the `FreeBSD Ports Version Check` informing you that a newer version of your port's distfile is available.
 More information about that system (including how to stop future emails) will be provided in the message.
 . Incorporate changes
-+ 
++
 When they become available, incorporate the changes into the port.
 You need to be able to generate a patch between the original port and your updated port.
 . Review and test
-+ 
++
 Thoroughly review and test your changes:
 
 ** Build, install and test your port on as many platforms and architectures as you can. It is common for a port to work on one branch or platform and fail on another.
 ** Make sure your port's dependencies are complete. The recommended way of doing this is by installing your own ports tinderbox. See <<resources>> for more information.
 ** Check that the packing list is up to date. This involves adding in any new files and directories and removing unused entries.
 ** Verify your port using man:portlint[1] as a guide. See <<resources>> for important information about using portlint.
 ** Consider whether changes to your port might cause any other ports to break. If this is the case, coordinate the changes with the maintainers of those ports. This is especially important if your update changes the shared library version; in this case, at the very least, the dependent ports will need to get a `PORTREVISION` bump so that they will automatically be upgraded by automated tools such as portmaster or man:portupgrade[1].
 
 . Submit changes
-+ 
++
 Send your update by submitting a PR with an explanation of the changes and a patch containing the differences between the original port and the updated one.
 Please refer to link:{problem-reports}[Writing FreeBSD Problem Reports] for information on how to write a really good PR.
 +
 [NOTE]
 ======
 Please do not submit a man:shar[1] archive of the entire port; instead, use man:diff[1] `-ruN`.
 In this way, committers can much more easily see exactly what changes are being made.
 The Porter's Handbook section on link:{porters-handbook}#port-upgrading[Upgrading] has more information.
 ======
 . Wait
-+ 
++
 At some stage a committer will deal with your PR.
 It may take minutes, or it may take weeks - so please be patient.
 . Give feedback
-+ 
++
 If a committer finds a problem with your changes, they will most likely refer it back to you.
 A prompt response will help get your PR committed faster, and is better for maintaining a thread of conversation when trying to resolve any problems.
 . And Finally
-+ 
++
 Your changes will be committed and your port will have been updated.
 The PR will then be closed by the committer. That's it!
 ====
 
 ===== Ensure your ports continue to build correctly
 
 This section is about discovering and fixing problems that stop your ports from building correctly.
 
 FreeBSD only guarantees that the Ports Collection works on the `-STABLE` branches.
 In theory, you should be able to get by with running the latest release of each stable branch (since the ABIs are not supposed to change) but if you can run the branch, that is even better.
 
 Since the majority of FreeBSD installations run on PC-compatible machines (what is termed the `i386` architecture), we expect you to keep the port working on that architecture.
 We prefer that ports also work on the `amd64` architecture running native.
 It is completely fair to ask for help if you do not have one of these machines.
 
 [NOTE]
 ====
 The usual failure modes for non-`x86` machines are that the original programmers assumed that, for instance, pointers are `int`-s, or that a relatively lax older gcc compiler was being used.
 More and more, application authors are reworking their code to remove these assumptions - but if the author is not actively maintaining their code, you may need to do this yourself.
 ====
 
 These are the tasks you need to perform to ensure your port is able to be built:
 
 [.procedure]
 ====
 . Watch for build failures
-+ 
++
 Check your mail for mail from `pkg-fallout@FreeBSD.org` and the http://portscout.FreeBSD.org[distfiles scanner] to see if any of the port which are failing to build are out of date.
 . Collect information
-+ 
++
 Once you are aware of a problem, collect information to help you fix it.
 Build errors reported by `pkg-fallout` are accompanied by logs which will show you where the build failed.
 If the failure was reported to you by a user, ask them to send you information which may help in diagnosing the problem, such as:
 
 ** Build logs
 ** The commands and options used to build the port (including options set in [.filename]#/etc/make.conf#)
 ** A list of packages installed on their system as shown by man:pkg-info[8]
 ** The version of FreeBSD they are running as shown by man:uname[1] `-a`
 ** When their ports collection was last updated
 ** When their ports tree and [.filename]#INDEX# was last updated
 
 . Investigate and find a solution
-+ 
++
 Unfortunately there is no straightforward process to follow to do this.
 Remember, though: if you are stuck, ask for help! The {freebsd-ports} is a good place to start, and the upstream developers are often very helpful.
 . Submit changes
-+ 
++
 Just as with updating a port, you should now incorporate changes, review and test, submit your changes in a PR, and provide feedback if required.
 . Send patches to upstream authors
-+ 
++
 In some cases, you will have to make patches to the port to make it run on FreeBSD.
 Some (but not all) upstream authors will accept such patches back into their code for the next release.
 If so, this may even help their users on other BSD-based systems as well and perhaps save duplicated effort.
 Please consider sending any applicable patches to the authors as a courtesy.
 ====
 
 ===== Investigate bug reports and PRs related to your port
 
 This section is about discovering and fixing bugs.
 
 FreeBSD-specific bugs are generally caused by assumptions about the build and runtime environments that do not apply to FreeBSD.
 You are less likely to encounter a problem of this type, but it can be more subtle and difficult to diagnose.
 
 These are the tasks you need to perform to ensure your port continues to work as intended:
 
 [.procedure]
 ====
 . Respond to bug reports
-+ 
++
 Bugs may be reported to you through email via the https://bugs.FreeBSD.org/search/[Problem Report database].
 Bugs may also be reported directly to you by users.
-+ 
++
 You should respond to PRs and other reports within 14 days, but please try not to take that long.
 Try to respond as soon as possible, even if it is just to say you need some more time before you can work on the PR.
-+ 
++
 If you have not responded after 14 days, any committer may commit from a PR that you have not responded to via a `maintainer-timeout`.
 . Collect information
-+ 
++
 If the person reporting the bug has not also provided a fix, you need to collect the information that will allow you to generate one.
-+ 
++
 If the bug is reproducible, you can collect most of the required information yourself.
 If not, ask the person who reported the bug to collect the information for you, such as:
 
 ** A detailed description of their actions, expected program behavior and actual behavior
 ** Copies of input data used to trigger the bug
 ** Information about their build and execution environment - for example, a list of installed packages and the output of man:env[1]
 ** Core dumps
 ** Stack traces
 
 . Eliminate incorrect reports
-+ 
++
 Some bug reports may be incorrect.
 For example, the user may have simply misused the program; or their installed packages may be out of date and require updating.
 Sometimes a reported bug is not specific to FreeBSD.
 In this case report the bug to the upstream developers.
 If the bug is within your capabilities to fix, you can also patch the port so that the fix is applied before the next upstream release.
 . Find a solution
-+ 
++
 As with build errors, you will need to sort out a fix to the problem.
 Again, remember to ask if you are stuck!
 . Submit or approve changes
-+ 
++
 Just as with updating a port, you should now incorporate changes, review and test, and submit your changes in a PR (or send a follow-up if a PR already exists for the problem).
 If another user has submitted changes in the PR, you can also send a follow-up saying whether or not you approve the changes.
 ====
 
 ===== Providing support
 
 Part of being a maintainer is providing support - not for the software in general - but for the port and any FreeBSD-specific quirks and problems.
 Users may contact you with questions, suggestions, problems and patches.
 Most of the time their correspondence will be specific to FreeBSD.
 
 Occasionally you may have to invoke your skills in diplomacy, and kindly point users seeking general support to the appropriate resources.
 Less frequently you will encounter a person asking why the `RPMS` are not up to date or how can they get the software to run under Foo Linux.
 Take the opportunity to tell them that your port is up to date (if it is, of course!), and suggest that they try FreeBSD.
 
 Sometimes users and developers will decide that you are a busy person whose time is valuable and do some of the work for you.
 For example, they might:
 
 * submit a PR or send you patches to update your port,
 * investigate and perhaps provide a fix to a PR, or
 * otherwise submit changes to your port.
 
 In these cases your main obligation is to respond in a timely manner.
 Again, the timeout for non-responsive maintainers is 14 days.
 After this period changes may be committed unapproved.
 They have taken the trouble to do this for you; so please try to at least respond promptly.
 Then review, approve, modify or discuss their changes with them as soon as possible.
 
 If you can make them feel that their contribution is appreciated (and it should be) you will have a better chance persuading them to do more things for you in the future :-).
 
 [[fix-broken]]
 === Finding and fixing a broken port
 
 There are some really good places to find a port that needs some attention.
 
 You can use the https://bugs.freebsd.org/search[web interface] to the Problem Report database to search through and view unresolved PRs.
 The majority of ports PRs are updates, but with a little searching and skimming over synopses you should be able to find something interesting to work on (the `sw-bug` class is a good place to start).
 
 The other place is the http://portsmon.FreeBSD.org/[FreeBSD Ports Monitoring System].
 In particular look for unmaintained ports with build errors and ports that are marked `BROKEN`.
 
 https://portsfallout.com/[PortsFallout] shows port issues gathered from the FreeBSD package building.
 
 It is OK to send changes for a maintained port as well, but remember to ask the maintainer in case they are already working on the problem.
 
 Once you have found a bug or problem, collect information, investigate and fix! If there is an existing PR, follow up to that.
 Otherwise create a new PR.
 Your changes will be reviewed and, if everything checks out, committed.
 
 [NOTE]
 ======
 The FreeBSD Ports Monitoring System (portsmon) is currently not working due to latest Python updates.
 ======
 
 [[mortal-coil]]
 === When to call it quits
 
 As your interests and commitments change, you may find that you no longer have time to continue some (or all) of your ports contributions.
 That is fine! Please let us know if you are no longer using a port or have otherwise lost time or interest in being a maintainer.
 In this way we can go ahead and allow other people to try to work on existing problems with the port without waiting for your response.
 Remember, FreeBSD is a volunteer project, so if maintaining a port is no fun any more, it is probably time to let someone else do it!
 
 In any case, the Ports Management Team (`portmgr`) reserves the right to reset your maintainership if you have not actively maintained your port in some time.
 (Currently, this is set to 3 months.)
 By this, we mean that there are unresolved problems or pending updates that have not been worked on during that time.
 
 [[resources]]
 === Resources for ports maintainers and contributors
 
 The link:{porters-handbook}[Porter's Handbook] is your hitchhiker's guide to the ports system. Keep it handy!
 
 link:{problem-reports}[Writing FreeBSD Problem Reports] describes how to best formulate and submit a PR.
 In 2005 more than eleven thousand ports PRs were submitted! Following this article will greatly assist us in reducing the time needed to handle your PRs.
 
 The https://bugs.freebsd.org/bugzilla/query.cgi[Problem Report database].
 
 The http://portsmon.FreeBSD.org/[FreeBSD Ports Monitoring System (portsmon)] can show you cross-referenced information about ports such as build errors and problem reports.
 If you are a maintainer you can use it to check on the build status of your ports.
 As a contributor you can use it to find broken and unmaintained ports that need to be fixed.
 
 The http://portscout.FreeBSD.org[FreeBSD Ports distfile scanner (portscout)] can show you ports for which the distfiles are not fetchable.
 You can check on your own ports or use it to find ports that need their `MASTER_SITES` updated.
 
 package:ports-mgmt/poudriere[] is the most thorough way to test a port through the entire cycle of installation, packaging, and deinstallation.
 Documentation is located at the https://github.com/freebsd/poudriere[poudriere github repository]
 
 man:portlint[1] is an application which can be used to verify that your port conforms to many important stylistic and functional guidelines.
 portlint is a simple heuristic application, so you should use it __only as a guide__.
 If portlint suggests changes which seem unreasonable, consult the link:{porters-handbook}[Porter's Handbook] or ask for advice.
 
 The {freebsd-ports} is for general ports-related discussion.
 It is a good place to ask for help.
 You can https://lists.freebsd.org/mailman/listinfo[subscribe, or read and search the list archives].
 Reading the archives of the {freebsd-ports-bugs} and the {svn-ports-head} may also be of interest.
 
 https://portsfallout.com/[PortsFallout] is a place to help in searching for the https://lists.freebsd.org/pipermail/freebsd-pkg-fallout/[FreeBSD package-fallout archive].
 
 [[ideas-contributing]]
 == Getting Started in Other Areas
 
 Looking for something interesting to get started that is not mentioned elsewhere in this article? The FreeBSD Project has several Wiki pages containing areas within which new contributors can get ideas on how to get started.
 
 The https://wiki.freebsd.org/JuniorJobs[Junior Jobs] page has a list of projects that might be of interest to people just getting started in FreeBSD, and want to work on interesting things to get their feet wet.
 
 The https://wiki.freebsd.org/IdeasPage[Ideas Page] contains various "nice to have" or "interesting" things to work on in the Project.
diff --git a/documentation/content/en/articles/contributors/_index.adoc b/documentation/content/en/articles/contributors/_index.adoc
index 5309b2b062..12ddc082bd 100644
--- a/documentation/content/en/articles/contributors/_index.adoc
+++ b/documentation/content/en/articles/contributors/_index.adoc
@@ -1,182 +1,182 @@
 ---
 title: Contributors to FreeBSD
 description: A list of organizations and individuals who have contributed to FreeBSD
 trademarks: ["freebsd", "sun", "general"]
 tags: ["Contributors", "FreeBSD", "individuals", "organizations"]
 ---
 
 = Contributors to FreeBSD
 :doctype: article
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 [.abstract-title]
 Abstract
 
 This article lists individuals and organizations who have made a contribution to FreeBSD.
 
 '''
 
 toc::[]
 
 [[donors]]
 == Donors Gallery
 
 [NOTE]
 ====
 As of 2010, the following section is several years out-of-date. Donations from the past several years appear https://www.FreeBSD.org/donations/donors/[here].
 ====
 
 The FreeBSD Project is indebted to the following donors and would like to publicly thank them here!
 
 * _Contributors to the central server project:_
 The following individuals and businesses made it possible for the FreeBSD Project to build a new central server machine, which has replaced `freefall.FreeBSD.org` at one point, by donating the following items:
 
 ** {mbarkah} and his employer, http://www.hemi.com/[ Hemisphere Online], donated a _Pentium Pro (P6) 200MHz CPU_
 ** http://www.asacomputers.com/[ASA Computers] donated a _Tyan 1662 motherboard_.
 ** Joe McGuckin mailto:joe@via.net[joe@via.net] of http://www.via.net/[ViaNet Communications] donated a _Kingston ethernet controller._
 ** Jack O'Neill mailto:jack@diamond.xtalwind.net[jack@diamond.xtalwind.net] donated an _NCR 53C875 SCSI controller card_.
 ** Ulf Zimmermann mailto:ulf@Alameda.net[ulf@Alameda.net] of http://www.Alameda.net/[Alameda Networks] donated _128MB of memory_, a _4 Gb disk drive and the case._
 
 * _Direct funding:_
-+ 
++
 The following individuals and businesses have generously contributed direct funding to the project:
 
 ** Annelise Anderson mailto:ANDRSN@HOOVER.STANFORD.EDU[ANDRSN@HOOVER.STANFORD.EDU]
 ** {dillon}
 ** http://www.bluemountain.com/[Blue Mountain Arts]
 ** http://www.epilogue.com/[Epilogue Technology Corporation]
 ** {sef}
 ** http://www.gta.com/[Global Technology Associates, Inc]
 ** Don Scott Wilde
 ** Gianmarco Giovannelli mailto:gmarco@masternet.it[gmarco@masternet.it]
 ** Josef C. Grosch mailto:joeg@truenorth.org[joeg@truenorth.org]
 ** Robert T. Morris
 ** {chuckr}
 ** Kenneth P. Stox mailto:ken@stox.sa.enteract.com[ken@stox.sa.enteract.com] of http://www.imagescape.com/[Imaginary Landscape, LLC.]
 ** Dmitry S. Kohmanyuk mailto:dk@dog.farm.org[dk@dog.farm.org]
 ** http://www.cdrom.co.jp/[Laser5] of Japan (a portion of the profits from sales of their various FreeBSD CDROMs).
 ** http://www.mmjp.or.jp/fuki/[Fuki Shuppan Publishing Co.] donated a portion of their profits from _Hajimete no FreeBSD_ (FreeBSD, Getting started) to the FreeBSD and XFree86 projects.
 ** http://www.ascii.co.jp/[ASCII Corp.] donated a portion of their profits from several FreeBSD-related books to the FreeBSD project.
 ** http://www.yokogawa.co.jp/[Yokogawa Electric Corp] has generously donated significant funding to the FreeBSD project.
 ** http://www.buffnet.net/[BuffNET]
 ** http://www.pacificsolutions.com/[Pacific Solutions]
 ** http://www.siemens.de/[Siemens AG] via Andre Albsmeier mailto:andre.albsmeier@mchp.siemens.de[andre.albsmeier@mchp.siemens.de]
 ** Chris Silva mailto:ras@interaccess.com[ras@interaccess.com]
 
 * _Hardware contributors:_
-+ 
++
 The following individuals and businesses have generously contributed hardware for testing and device driver development/support:
 
 ** BSDi for providing the Pentium P5-90 and 486/DX2-66 EISA/VL systems that are being used for our development work, to say nothing of the network access and other donations of hardware resources.
 ** http://www.compaq.com[Compaq] has donated a variety of Alpha systems to the FreeBSD Project. Among the many generous donations are 4 AlphaStation DS10s, an AlphaServer DS20, AlphaServer 2100s, an AlphaServer 4100, 8 500Mhz Personal Workstations, 4 433Mhz Personal Workstations, and more! These machines are used for release engineering, package building, SMP development, and general development on the Alpha architecture.
 ** TRW Financial Systems, Inc. provided 130 PCs, three 68 GB file servers, twelve Ethernets, two routers and an ATM switch for debugging the diskless code.
 ** Dermot McDonnell donated the Toshiba XM3401B CDROM drive currently used in freefall.
 ** Chuck Robey mailto:chuckr@glue.umd.edu[chuckr@glue.umd.edu] contributed his floppy tape streamer for experimental work.
 ** Larry Altneu mailto:larry@ALR.COM[larry@ALR.COM], and {wilko}, provided Wangtek and Archive QIC-02 tape drives in order to improve the [.filename]#wt# driver.
 ** Ernst Winter (http://berklix.org/ewinter/[Deceased]) contributed a 2.88 MB floppy drive to the project. This will hopefully increase the pressure for rewriting the floppy disk driver.
 ** http://www.tekram.com/[Tekram Technologies] sent one each of their DC-390, DC-390U and DC-390F FAST and ULTRA SCSI host adapter cards for regression testing of the NCR and AMD drivers with their cards. They are also to be applauded for making driver sources for free operating systems available from their FTP server link:ftp://ftp.tekram.com/scsi/FreeBSD/[ftp://ftp.tekram.com/scsi/FreeBSD/].
 ** Larry M. Augustin contributed not only a Symbios Sym8751S SCSI card, but also a set of data books, including one about the forthcoming Sym53c895 chip with Ultra-2 and LVD support, and the latest programming manual with information on how to safely use the advanced features of the latest Symbios SCSI chips. Thanks a lot!
 ** {kuku} donated an FX120 12 speed Mitsumi CDROM drive for IDE CDROM driver development.
 ** Mike Tancsa mailto:mike@sentex.ca[mike@sentex.ca] donated four various ATM PCI cards in order to help increase support of these cards as well as help support the development effort of the netatm ATM stack.
 
 * _Special contributors:_
 
 ** http://www.osd.bsdi.com/[BSDi] (formerly Walnut Creek CDROM) has donated almost more than we can say (see the 'About the FreeBSD Project' section of the link:{handbook}[FreeBSD Handbook] for more details). In particular, we would like to thank them for the original hardware used for `freefall.FreeBSD.org`, our primary development machine, and for `thud.FreeBSD.org`, a testing and build box. We are also indebted to them for funding various contributors over the years and providing us with unrestricted use of their T1 connection to the Internet.
 ** The http://www.interface-business.de/[interface business GmbH, Dresden] has been patiently supporting {joerg} who has often preferred FreeBSD work over paid work, and used to fall back to their (quite expensive) EUnet Internet connection whenever his private connection became too slow or flaky to work with it...
 ** http://www.bsdi.com/[Berkeley Software Design, Inc.] has contributed their DOS emulator code to the remaining BSD world, which is used in the _doscmd_ command.
 
 [[staff-committers]]
 == The FreeBSD Developers
 
 These are the people who have commit privileges and do the engineering work on the FreeBSD source tree.
 All core team members are also developers.
 
 (in alphabetical order by last name):
 
 include::{include-path}contrib-committers.adoc[]
 
 [[contrib-corealumni]]
 == Core Team Alumni
 
 The following people were members of the FreeBSD core team during the periods indicated.
 We thank them for their past efforts in the service of the FreeBSD project.
 
 _In rough reverse chronological order:_
 
 include::{include-path}contrib-corealumni.adoc[]
 
 [[contrib-develalumni]]
 == Development Team Alumni
 
 The following people were members of the FreeBSD development team during the periods indicated.
 We thank them for their past efforts in the service of the FreeBSD project.
 
 _In rough reverse chronological order:_
 
 include::{include-path}contrib-develalumni.adoc[]
 
 [[contrib-portmgralumni]]
 == Ports Management Team Alumni
 
 The following people were members of the FreeBSD portmgr team during the periods indicated.
 We thank them for their past efforts in the service of the FreeBSD project.
 
 _In rough reverse chronological order:_
 
 include::{include-path}contrib-portmgralumni.adoc[]
 
 [[contrib-develinmemoriam]]
 == Development Team: In Memoriam
 
 During the many years that the FreeBSD Project has been in existence, sadly, some of our developers have passed away.
 Here are some remembrances.
 
 _In rough reverse chronological order of their passing:_
 
 include::{include-path}contrib-develinmemoriam.adoc[]
 
 [[contrib-derived]]
 == Derived Software Contributors
 
 This software was originally derived from William F. Jolitz's 386BSD release 0.1, though almost none of the original 386BSD specific code remains.
 This software has been essentially re-implemented from the 4.4BSD-Lite release provided by the Computer Science Research Group (CSRG) at the University of California, Berkeley and associated academic contributors.
 
 There are also portions of NetBSD and OpenBSD that have been integrated into FreeBSD as well, and we would therefore like to thank all the contributors to NetBSD and OpenBSD for their work.
 
 [[contrib-additional]]
 == Additional FreeBSD Contributors
 
 (in alphabetical order by first name):
 
 include::{include-path}contrib-additional.adoc[]
 
 [[contrib-386bsd]]
 == 386BSD Patch Kit Patch Contributors
 
 (in alphabetical order by first name):
 
 include::{include-path}contrib-386bsd.adoc[]
diff --git a/documentation/content/en/articles/contributors/contrib-develinmemoriam.adoc b/documentation/content/en/articles/contributors/contrib-develinmemoriam.adoc
index 943213810b..84c5e2af05 100644
--- a/documentation/content/en/articles/contributors/contrib-develinmemoriam.adoc
+++ b/documentation/content/en/articles/contributors/contrib-develinmemoriam.adoc
@@ -1,60 +1,60 @@
 
 * Bruce D. Evans (1991 - 2019; RIP 2019)
-+ 
++
 Bruce was a programming giant who made FreeBSD his home.
-+ 
++
 Back before FreeBSD and Linux there was Minix, a toy "unix" written by Andy Tannenbaum, released in 1987, sold with complete sources on three floppy disks, for $99.
-+ 
++
 Bruce ported Minix to the i386 around 1989.
-+ 
++
 Linus Torvalds used Minix/386 to develop his own kernel, and Bruce was the first person he thanked in the release-announcement.
-+ 
++
 When Bill Jolitz released 386BSD 0.1 in 1992, Bruce was listed as a contributor.
-+ 
++
 Bruce co-founded the FreeBSD project, and served on core.0, but he was never partisan, and over the years many other projects have benefitted from his patches, advice and wisdom.
-+ 
++
 Code reviews from Bruce came in three flavours, "mild", "brucified" and "brucifiction", but they were never personal: It was always only about the code, the mistakes, the sloppy thinking, the missing historical context, the ambiguous standards - and the style(9) transgressions.
-+ 
++
 As Bruce gave more code reviews than anybody else in the history of the FreeBSD project, the commit logs hide the true scale of his impact until you pay attention to "Submitted by", "Reviewed by" and "Pointed out by".
-+ 
++
 Being hard of hearing, Bruce did not attend conferences.
-+ 
++
 The notable exception was the 1999 BSDcon in California, where his core team colleagues greeted him with "We're not worthy!" in Wayne's World fashion.
-+ 
++
 Twenty years later we're still not.
 * Kurt Lidl (2015 - 2019; RIP 2019)
-+ 
++
 Kurt first got involved with BSD while it was still a project at the University of California at Berkeley. Shortly after personalized license plates became available in Maryland, he got "BSDWZRD".
-+ 
++
 He began contributing to FreeBSD shortly after the conception of the project. He became a FreeBSD source committer in October 2015.
-+ 
++
 Kurt's most well known FreeBSD project was man:blacklistd[8] which blocks and releases ports on demand to avoid DoS abuse. He has also made many other bug fixes and enhancements to DTrace, boot loaders, and other bits and pieces of the FreeBSD infrastructure.
-+ 
++
 Earlier work included the game XTank, an author on RFC 2516 https://tools.ietf.org/html/rfc2516["A Method for Transmitting PPP Over Ethernet (PPPoE)"], and the USENIX paper https://www.usenix.org/conference/usenix-winter-1994-technical-conference/drinking-firehose-multicast-usenet-news["Drinking from the Firehose: Multicast USENET News"].
 * Frank Durda IV (1995 - 2003; RIP 2018)
-+ 
++
 Frank had been around the project since the very early days, contributing code to the 1.x line before becoming a committer.
 * Andrey A. Chernov (1993 - 2017; RIP 2017)
-+ 
++
 Andrey contributions to FreeBSD can not be overstated. Having been involved for a long there is hardly an area which he did not touch.
 * Jürgen Lock (2006 - 2015; RIP 2015)
-+ 
++
 Jürgen made a number of contributions to FreeBSD, including work on libvirt, the graphics stack, and QEMU. Jürgen's contributions and helpfulness were appreciated by people around the world. That work continues to improve the lives of thousands every day.
 * {alexbl} (2006 - 2011; RIP 2012)
-+ 
++
 http://www.legacy.com/obituaries/sfgate/obituary.aspx?pid=159801494[Alexander] was best known as a major contributor to FreeBSD's Python ports and a founding member of {python} as well as his work on XMMS2.
 * {jb} (1997 - 2009; RIP 2009)
-+ 
++
 http://hub.opensolaris.org/bin/view/Community+Group+ogb/In+Memoriam[John] made major contributions to FreeBSD, the best known of which is the import of the man:dtrace[1] code. John's unique sense of humor and plain-spokenness either ruffled feathers or made him quick friends. At the end of his life, he had moved to a rural area and was attempting to live with as minimal impact to the planet as possible, while at the same time still working in the high-tech area.
 * {jmz} (1994 - 2009; RIP 2009)
-+ 
++
 http://www.obs-besancon.fr/article.php3?id_article=323[Jean-Marc] was an astrophysicist who made important contributions to the modeling of the atmospheres of both planets and comets at http://www.obs-besancon.fr/[l'Observatoire de Besançon] in Besançon, France. While there, he participated in the conception and construction of the Vega tricanal spectrometer that studied Halley's Comet. He had also been a long-time contributor to FreeBSD.
 * {itojun} (1997 - 2001; RIP 2008)
-+ 
++
 Known to everyone as http://astralblue.livejournal.com/350702.html[itojun], Jun-ichiro Hagino was a core researcher at the http://www.kame.net/[KAME Project], which aimed to provide IPv6 and IPsec technology in freely redistributable form. Much of this code was incorporated into FreeBSD. Without his efforts, the state of IPv6 on the Internet would be much different.
 * {cg} (1999 - 2005; RIP 2005)
-+ 
++
 http://www.dbsi.org/cam/[Cameron] was a unique individual who contributed to the project despite serious physical disabilities. He was responsible for a complete rewrite of our sound system during the late 1990s. Many of those who corresponded with him had no idea of his limited mobility, due to his cheerful spirit and willingness to help others.
 * {alane} (2002 - 2003; RIP 2003)
-+ 
++
 http://freebsd.kde.org/memoriam/alane.php[Alan] was a major contributor to the KDE on FreeBSD group. In addition, he maintained many other difficult and time-consuming ports such as autoconf, CUPS, and python. Alan's path was not an easy one but his passion for FreeBSD, and dedication to programming excellence, won him many friends.
diff --git a/documentation/content/en/articles/explaining-bsd/_index.adoc b/documentation/content/en/articles/explaining-bsd/_index.adoc
index ed3c4cd7a7..a8f6359fb7 100644
--- a/documentation/content/en/articles/explaining-bsd/_index.adoc
+++ b/documentation/content/en/articles/explaining-bsd/_index.adoc
@@ -1,212 +1,212 @@
 ---
 title: Explaining BSD
 authors:
   - author: Greg Lehey
     email: grog@FreeBSD.org
 description: Brief explanation about BSD
 trademarks: ["freebsd", "amd", "apple", "intel", "linux", "opengroup", "sun", "unix", "general"]
 tags: ["Explaining BSD", "BSD", "FreeBSD", "operating system"]
 ---
 
 = Explaining BSD
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :source-highlighter: rouge
 :experimental:
 :sectnumlevels: 6
 
 [.abstract-title]
 Abstract
 
 In the open source world, the word "Linux" is almost synonymous with "Operating System", but it is not the only open source UNIX(R) operating system.
 
 So what is the secret? Why is BSD not better known? This white paper addresses these and other questions.
 
 Throughout this paper, differences between BSD and Linux will be noted __like this__.
 
 '''
 
 toc::[]
 
 [[what-is-bsd]]
 == What is BSD?
 
 BSD stands for "Berkeley Software Distribution".
 It is the name of distributions of source code from the University of California, Berkeley, which were originally extensions to AT&T's Research UNIX(R) operating system.
 Several open source operating system projects are based on a release of this source code known as 4.4BSD-Lite.
 In addition, they comprise a number of packages from other Open Source projects, including notably the GNU project.
 The overall operating system comprises:
 
 * The BSD kernel, which handles process scheduling, memory management, symmetric multi-processing (SMP), device drivers, etc.
 * The C library, the base API for the system.
-+ 
++
 __The BSD C library is based on code from Berkeley, not the GNU project.__
 * Utilities such as shells, file utilities, compilers and linkers.
-+ 
++
 __Some of the utilities are derived from the GNU project, others are not.__
 * The X Window system, which handles graphical display.
-+ 
++
 The X Window system used in most versions of BSD is maintained by the http://www.X.org/[X.Org project].
 FreeBSD allows the user to choose from a variety of desktop environments, such as Gnome, KDE, or Xfce; and lightweight window managers like Openbox, Fluxbox, or Awesome.
 * Many other programs and utilities.
 
 [[what-a-real-unix]]
 == What, a real UNIX(R)?
 
 The BSD operating systems are not clones, but open source derivatives of AT&T's Research UNIX(R) operating system, which is also the ancestor of the modern UNIX(R) System V.
 This may surprise you.
 How could that happen when AT&T has never released its code as open source?
 
 It is true that AT&T UNIX(R) is not open source, and in a copyright sense BSD is very definitely _not_ UNIX(R), but on the other hand, AT&T has imported sources from other projects, noticeably the Computer Sciences Research Group (CSRG) of the University of California in Berkeley, CA. Starting in 1976, the CSRG started releasing tapes of their software, calling them _Berkeley Software Distribution_ or __BSD__.
 
 Initial BSD releases consisted mainly of user programs, but that changed dramatically when the CSRG landed a contract with the Defense Advanced Research Projects Agency (DARPA) to upgrade the communications protocols on their network, ARPANET.
 The new protocols were known as the __Internet Protocols__, later _TCP/IP_ after the most important protocols.
 The first widely distributed implementation was part of 4.2BSD, in 1982.
 
 In the course of the 1980s, a number of new workstation companies sprang up.
 Many preferred to license UNIX(R) rather than developing operating systems for themselves.
 In particular, Sun Microsystems licensed UNIX(R) and implemented a version of 4.2BSD, which they called SunOS(TM).
 When AT&T themselves were allowed to sell UNIX(R) commercially, they started with a somewhat bare-bones implementation called System III, to be quickly followed by System V.
 The System V code base did not include networking, so all implementations included additional software from the BSD, including the TCP/IP software, but also utilities such as the _csh_ shell and the _vi_ editor.
 Collectively, these enhancements were known as the __Berkeley Extensions__.
 
 The BSD tapes contained AT&T source code and thus required a UNIX(R) source license.
 By 1990, the CSRG's funding was running out, and it faced closure.
 Some members of the group decided to release the BSD code, which was Open Source, without the AT&T proprietary code.
 This finally happened with the __Networking Tape 2__, usually known as __Net/2__.
 Net/2 was not a complete operating system: about 20% of the kernel code was missing.
 One of the CSRG members, William F. Jolitz, wrote the remaining code and released it in early 1992 as __386BSD__.
 At the same time, another group of ex-CSRG members formed a commercial company called http://www.bsdi.com/[Berkeley Software Design Inc.] and released a beta version of an operating system called http://www.bsdi.com/[BSD/386], which was based on the same sources.
 The name of the operating system was later changed to BSD/OS.
 
 386BSD never became a stable operating system.
 Instead, two other projects split off from it in 1993: http://www.NetBSD.org/[NetBSD] and link:https://www.FreeBSD.org/[FreeBSD].
 The two projects originally diverged due to differences in patience waiting for improvements to 386BSD: the NetBSD people started early in the year, and the first version of FreeBSD was not ready until the end of the year.
 In the meantime, the code base had diverged sufficiently to make it difficult to merge.
 In addition, the projects had different aims, as we will see below. In 1996, http://www.OpenBSD.org/[OpenBSD] split off from NetBSD, and in 2003, http://www.dragonflybsd.org/[DragonFlyBSD] split off from FreeBSD.
 
 [[why-is-bsd-not-better-known]]
 == Why is BSD not better known?
 
 For a number of reasons, BSD is relatively unknown:
 
 . The BSD developers are often more interested in polishing their code than marketing it.
 . Much of Linux's popularity is due to factors external to the Linux projects, such as the press, and to companies formed to provide Linux services. Until recently, the open source BSDs had no such proponents.
 . In 1992, AT&T sued http://www.bsdi.com/[BSDI], the vendor of BSD/386, alleging that the product contained AT&T-copyrighted code. The case was settled out of court in 1994, but the spectre of the litigation continues to haunt people. In March 2000 an article published on the web claimed that the court case had been "recently settled".
-+ 
++
 One detail that the lawsuit did clarify is the naming: in the 1980s, BSD was known as "BSD UNIX(R)".
 With the elimination of the last vestige of AT&T code from BSD, it also lost the right to the name UNIX(R).
 Thus you will see references in book titles to "the 4.3BSD UNIX(R) operating system" and "the 4.4BSD operating system".
 
 [[comparing-bsd-and-linux]]
 == Comparing BSD and Linux
 
 So what is really the difference between, say, Debian Linux and FreeBSD? For the average user, the difference is surprisingly small: Both are UNIX(R) like operating systems.
 Both are developed by non-commercial projects (this does not apply to many other Linux distributions, of course).
 In the following section, we will look at BSD and compare it to Linux.
 The description applies most closely to FreeBSD, which accounts for an estimated 80% of the BSD installations, but the differences from NetBSD, OpenBSD and DragonFlyBSD are small.
 
 === Who owns BSD?
 
 No one person or corporation owns BSD.
 It is created and distributed by a community of highly technical and committed contributors all over the world.
 Some of the components of BSD are Open Source projects in their own right and managed by different project maintainers.
 
 === How is BSD developed and updated?
 
 The BSD kernels are developed and updated following the Open Source development model.
 Each project maintains a publicly accessible _source tree_ which contains all source files for the project, including documentation and other incidental files. 
 Users can obtain a complete copy of any version.
 
 A large number of developers worldwide contribute to improvements to BSD.
 They are divided into three kinds:
 
 * _Contributors_ write code or documentation. They are not permitted to commit (add code) directly to the source tree. In order for their code to be included in the system, it must be reviewed and checked in by a registered developer, known as a __committer__.
 * _Committers_ are developers with write access to the source tree. In order to become a committer, an individual must show ability in the area in which they are active.
-+ 
++
 It is at the individual committer's discretion whether they should obtain authority before committing changes to the source tree.
 In general, an experienced committer may make changes which are obviously correct without obtaining consensus.
 For example, a documentation project committer may correct typographical or grammatical errors without review.
 On the other hand, developers making far-reaching or complicated changes are expected to submit their changes for review before committing them
 In extreme cases, a core team member with a function such as Principal Architect may order that changes be removed from the tree, a process known as _backing out_.
 All committers receive mail describing each individual commit, so it is not possible to commit secretly.
 * The _Core team_. FreeBSD and NetBSD each have a core team which manages the project. The core teams developed in the course of the projects, and their role is not always well-defined. It is not necessary to be a developer in order to be a core team member, though it is normal. The rules for the core team vary from one project to the other, but in general they have more say in the direction of the project than non-core team members have.
 
 This arrangement differs from Linux in a number of ways:
 
 . No one person controls the content of the system. In practice, this difference is overrated, since the Principal Architect can require that code be backed out, and even in the Linux project several people are permitted to make changes.
 . On the other hand, there _is_ a central repository, a single place where you can find the entire operating system sources, including all older versions.
 . BSD projects maintain the entire "Operating System", not only the kernel. This distinction is only marginally useful: neither BSD nor Linux is useful without applications. The applications used under BSD are frequently the same as the applications used under Linux.
 . As a result of the formalized maintenance of a single SVN source tree, BSD development is clear, and it is possible to access any version of the system by release number or by date. SVN also allows incremental updates to the system: for example, the FreeBSD repository is updated about 100 times a day. Most of these changes are small.
 
 === BSD releases
 
 FreeBSD, NetBSD and OpenBSD provide the system in three different "releases".
 As with Linux, releases are assigned a number such as 1.4.1 or 3.5.
 In addition, the version number has a suffix indicating its purpose:
 
 . The development version of the system is called _CURRENT_. FreeBSD assigns a number to CURRENT, for example FreeBSD 5.0-CURRENT. NetBSD uses a slightly different naming scheme and appends a single-letter suffix which indicates changes in the internal interfaces, for example NetBSD 1.4.3G. OpenBSD does not assign a number ("OpenBSD-current"). All new development on the system goes into this branch.
 . At regular intervals, between two and four times a year, the projects bring out a _RELEASE_ version of the system, which is available on CD-ROM and for free download from FTP sites, for example OpenBSD 2.6-RELEASE or NetBSD 1.4-RELEASE. The RELEASE version is intended for end users and is the normal version of the system. NetBSD also provides _patch releases_ with a third digit, for example NetBSD 1.4.2.
 . As bugs are found in a RELEASE version, they are fixed, and the fixes are added to the SVN tree. In FreeBSD, the resultant version is called the _STABLE_ version, while in NetBSD and OpenBSD it continues to be called the RELEASE version. Smaller new features can also be added to this branch after a period of test in the CURRENT branch. Security and other important bug fixes are also applied to all supported RELEASE versions.
 
 _By contrast, Linux maintains two separate code trees: the stable version and the development version.
 Stable versions have an even minor version number, such as 2.0, 2.2 or 2.4.
 Development versions have an odd minor version number, such as 2.1, 2.3 or 2.5.
 In each case, the number is followed by a further number designating the exact release.
 In addition, each vendor adds their own userland programs and utilities, so the name of the distribution is also important.
 Each distribution vendor also assigns version numbers to the distribution, so a complete description might be something like "TurboLinux 6.0 with kernel 2.2.14"_
 
 === What versions of BSD are available?
 
 In contrast to the numerous Linux distributions, there are only four major open source BSDs. Each BSD project maintains its own source tree and its own kernel. In practice, though, there appear to be fewer divergences between the userland code of the projects than there is in Linux.
 
 It is difficult to categorize the goals of each project: the differences are very subjective. Basically,
 
 * FreeBSD aims for high performance and ease of use by end users, and is a favourite of web content providers. It runs on a link:https://www.FreeBSD.org/platforms/[number of platforms] and has significantly more users than the other projects.
 * NetBSD aims for maximum portability: "of course it runs NetBSD". It runs on machines from palmtops to large servers, and has even been used on NASA space missions. It is a particularly good choice for running on old non-Intel(R) hardware.
 * OpenBSD aims for security and code purity: it uses a combination of the open source concept and rigorous code reviews to create a system which is demonstrably correct, making it the choice of security-conscious organizations such as banks, stock exchanges and US Government departments. Like NetBSD, it runs on a number of platforms.
 * DragonFlyBSD aims for high performance and scalability under everything from a single-node UP system to a massively clustered system. DragonFlyBSD has several long-range technical goals, but focus lies on providing a SMP-capable infrastructure that is easy to understand, maintain and develop for.
 
 There are also two additional BSD UNIX(R) operating systems which are not open source, BSD/OS and Apple's Mac OS(R) X:
 
 * BSD/OS was the oldest of the 4.4BSD derivatives. It was not open source, though source code licenses were available at relatively low cost. It resembled FreeBSD in many ways. Two years after the acquisition of BSDi by Wind River Systems, BSD/OS failed to survive as an independent product. Support and source code may still be available from Wind River, but all new development is focused on the VxWorks embedded operating system.
 * http://www.apple.com/macosx/server/[Mac OS(R) X] is the latest version of the operating system for Apple(R)'s Mac(R) line. The BSD core of this operating system, http://developer.apple.com/darwin/[Darwin], is available as a fully functional open source operating system for x86 and PPC computers. The Aqua/Quartz graphics system and many other proprietary aspects of Mac OS(R) X remain closed-source, however. Several Darwin developers are also FreeBSD committers, and vice-versa.
 
 === How does the BSD license differ from the GNU Public license?
 
 Linux is available under the http://www.fsf.org/copyleft/gpl.html[GNU General Public License] (GPL), which is designed to eliminate closed source software.
 In particular, any derivative work of a product released under the GPL must also be supplied with source code if requested.
 By contrast, the http://www.opensource.org/licenses/bsd-license.html[BSD license] is less restrictive: binary-only distributions are allowed.
 This is particularly attractive for embedded applications.
 
 === What else should I know?
 
 Since fewer applications are available for BSD than Linux, the BSD developers created a Linux compatibility package, which allows Linux programs to run under BSD.
 The package includes both kernel modifications, in order to correctly perform Linux system calls, and Linux compatibility files such as the C library.
 There is no noticeable difference in execution speed between a Linux application running on a Linux machine and a Linux application running on a BSD machine of the same speed.
 
 The "all from one supplier" nature of BSD means that upgrades are much easier to handle than is frequently the case with Linux.
 BSD handles library version upgrades by providing compatibility modules for earlier library versions, so it is possible to run binaries which are several years old with no problems.
 
 === Which should I use, BSD or Linux?
 
 What does this all mean in practice? Who should use BSD, who should use Linux?
 
 This is a very difficult question to answer.
 Here are some guidelines:
 
 * "If it ain't broke, don't fix it": If you already use an open source operating system, and you are happy with it, there is probably no good reason to change.
 * BSD systems, in particular FreeBSD, can have notably higher performance than Linux. But this is not across the board. In many cases, there is little or no difference in performance. In some cases, Linux may perform better than FreeBSD.
 * In general, BSD systems have a better reputation for reliability, mainly as a result of the more mature code base.
 * BSD projects have a better reputation for the quality and completeness of their documentation. The various documentation projects aim to provide actively updated documentation, in many languages, and covering all aspects of the system.
 * The BSD license may be more attractive than the GPL.
 * BSD can execute most Linux binaries, while Linux can not execute BSD binaries. Many BSD implementations can also execute binaries from other UNIX(R) like systems. As a result, BSD may present an easier migration route from other systems than Linux would.
 
 === Who provides support, service, and training for BSD?
 
 BSDi / http://www.freebsdmall.com[FreeBSD Mall, Inc.] have been providing support contracts for FreeBSD for nearly a decade.
 
 In addition, each of the projects has a list of consultants for hire: link:https://www.FreeBSD.org/commercial/consult_bycat/[FreeBSD], http://www.netbsd.org/gallery/consultants.html[NetBSD], and http://www.openbsd.org/support.html[OpenBSD].
diff --git a/documentation/content/en/articles/fonts/_index.adoc b/documentation/content/en/articles/fonts/_index.adoc
index 10a72252b0..8ff9e387a9 100644
--- a/documentation/content/en/articles/fonts/_index.adoc
+++ b/documentation/content/en/articles/fonts/_index.adoc
@@ -1,582 +1,582 @@
 ---
 title: Fonts and FreeBSD
 subtitle: A Tutorial
 authors:
   - author: Dave Bodenstab
     email: imdave@synet.net
 description: A description of the various font technologies in FreeBSD, and how to use them with different programs
 trademarks: ["freebsd", "adobe", "apple", "linux", "microsoft", "opengroup", "general"]
 tags: ["Fonts", "syscons", "X11", "Ghostscript", "Groff", "guide", "tutorial", "FreeBSD"]
 ---
 
 = Fonts and FreeBSD
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :source-highlighter: rouge
 :experimental:
 :sectnumlevels: 6
 
 [.abstract-title]
 Abstract
 
 This document contains a description of the various font files that may be used with FreeBSD and the syscons driver, X11, Ghostscript and Groff.
 Cookbook examples are provided for switching the syscons display to 80x60 mode, and for using type 1 fonts with the above application programs.
 
 '''
 
 toc::[]
 
 [[intro]]
 == Introduction
 
 There are many sources of fonts available, and one might ask how they might be used with FreeBSD.
 The answer can be found by carefully searching the documentation for the component that one would like to use.
 This is very time consuming, so this tutorial is an attempt to provide a shortcut for others who might be interested.
 
 [[terminology]]
 == Basic Terminology
 
 There are many different font formats and associated font file suffixes.
 A few that will be addressed here are:
 
 [.filename]#.pfa#, [.filename]#.pfb#::
 PostScript(R) type 1 fonts. The [.filename]#.pfa# is the __A__scii form and [.filename]#.pfb# the __B__inary form.
 
 [.filename]#.afm#::
 The font metrics associated with a type 1 font.
 
 [.filename]#.pfm#::
 The printer font metrics associated with a type 1 font.
 
 [.filename]#.ttf#::
 A TrueType(R) font
 
 [.filename]#.fot#::
 An indirect reference to a TrueType font (not an actual font)
 
 [.filename]#.fon#, [.filename]#.fnt#::
 Bitmapped screen fonts
 
 The [.filename]#.fot# is used by Windows(R) as sort of a symbolic link to the actual TrueType(R) font ([.filename]#.ttf#) file. The [.filename]#.fon# font files are also used by Windows.
 I know of no way to use this font format with FreeBSD.
 
 [[font-formats]]
 == What Font Formats Can I Use?
 
 Which font file format is useful depends on the application being used.
 FreeBSD by itself uses no fonts.
 Application programs and/or drivers may make use of the font files.
 Here is a small cross reference of application/driver to the font type suffixes:
 
 Driver::
 
 vt:::
 [.filename]#.hex#
 
 syscons:::
 [.filename]#.fnt#
 
 Application::
 
 Ghostscript:::
 [.filename]#.pfa#, [.filename]#.pfb#, [.filename]#.ttf#
 
 X11:::
 [.filename]#.pfa#, [.filename]#.pfb#
 
 Groff:::
 [.filename]#.pfa#, [.filename]#.afm#
 
 Povray:::
 [.filename]#.ttf#
 
 The [.filename]#.fnt# suffix is used quite frequently.
 I suspect that whenever someone wanted to create a specialized font file for their application, more often than not they chose this suffix.
 Therefore, it is likely that files with this suffix are not all the same format; specifically, the [.filename]#.fnt# files used by syscons under FreeBSD may not be the same format as a [.filename]#.fnt# one encounters in the MS-DOS(R)/Windows(R) environment.
 I have not made any attempt at using other [.filename]#.fnt# files other than those provided with FreeBSD.
 
 [[virtual-console]]
 == Setting a Virtual Console to 80x60 Line Mode
 
 First, an 8x8 font must be loaded.
 To do this, [.filename]#/etc/rc.conf# should contain the line (change the font name to an appropriate one for your locale):
 
 [.programlisting]
 ....
 font8x8="iso-8x8"		# font 8x8 from /usr/share/syscons/fonts/* (or NO).
 ....
 
 The command to actually switch the mode is man:vidcontrol[1]:
 
 [source,shell]
 ....
 % vidcontrol VGA_80x60
 ....
 
 Various screen-oriented programs, such as man:vi[1], must be able to determine the current screen dimensions.
 As this is achieved this through `ioctl` calls to the console driver (such as man:syscons[4]) they will correctly determine the new screen dimensions.
 
 To make this more seamless, one can embed these commands in the startup scripts so it takes place when the system boots.
 To do this is add this line to [.filename]#/etc/rc.conf#.
 
 [.programlisting]
 ....
 allscreens_flags="VGA_80x60"	# Set this vidcontrol mode for all virtual screens
 ....
 
 References: man:rc.conf[5], man:vidcontrol[1].
 
 [[type1-fonts-x11]]
 == Using Type 1 Fonts with X11
 
 X11 can use either the [.filename]#.pfa# or the [.filename]#.pfb# format fonts.
 The X11 fonts are located in various subdirectories under [.filename]#/usr/X11R6/lib/X11/fonts#.
 Each font file is cross referenced to its X11 name by the contents of [.filename]#fonts.dir# in each directory.
 
 There is already a directory named [.filename]#Type1#.
 The most straight forward way to add a new font is to put it into this directory.
 A better way is to keep all new fonts in a separate directory and use a symbolic link to the additional font.
 This allows one to more easily keep track of ones fonts without confusing them with the fonts that were originally provided.
 For example:
 
 [source,shell]
 ....
 Create a directory to contain the font files
 % mkdir -p /usr/local/share/fonts/type1
 % cd /usr/local/share/fonts/type1
 
 Place the .pfa, .pfb and .afm files here
 
 One might want to keep readme files, and other documentation
 
 for the fonts here also
 % cp /cdrom/fonts/atm/showboat/showboat.pfb .
 % cp /cdrom/fonts/atm/showboat/showboat.afm .
 
 Maintain an index to cross reference the fonts
 % echo showboat - InfoMagic CICA, Dec 1994, /fonts/atm/showboat >>INDEX
 ....
 
 Now, to use a new font with X11, one must make the font file available and update the font name files.
 The X11 font names look like:
 
 [.programlisting]
 ....
 -bitstream-charter-medium-r-normal-xxx-0-0-0-0-p-0-iso8859-1
      |        |      |    |   |     |  | | | | | |    \    \
      |        |      |    |   |     \  \ \ \ \ \ \     +----+- character set
      |        |      |    |   \      \  \ \ \ \ \ +- average width
      |        |      |    |    \      \  \ \ \ \ +- spacing
      |        |      |    \	\      \  \ \ \ +- vertical res.
      |        |      |     \	 \	\  \ \ +- horizontal res.
      |        |      |      \	  \	 \  \ +- points
      |        |      |       \     \	  \  +- pixels
      |        |      |        \     \	   \
   foundry  family  weight   slant  width  additional style
 ....
 
 A new name needs to be created for each new font.
 If you have some information from the documentation that accompanied the font, then it could serve as the basis for creating the name.
 If there is no information, then you can get some idea by using man:strings[1] on the font file.
 For example:
 
 [source,shell]
 ....
 % strings showboat.pfb | more
 %!FontType1-1.0: Showboat 001.001
 %%CreationDate: 1/15/91 5:16:03 PM
 %%VMusage: 1024 45747
 % Generated by Fontographer 3.1
 % Showboat
  1991 by David Rakowski.  Alle Rechte Vorbehalten.
 FontDirectory/Showboat known{/Showboat findfont dup/UniqueID known{dup
 /UniqueID get 4962377 eq exch/FontType get 1 eq and}{pop false}ifelse
 {save true}{false}ifelse}{false}ifelse
 12 dict begin
 /FontInfo 9 dict dup begin
  /version (001.001) readonly def
  /FullName (Showboat) readonly def
  /FamilyName (Showboat) readonly def
  /Weight (Medium) readonly def
  /ItalicAngle 0 def
  /isFixedPitch false def
  /UnderlinePosition -106 def
  /UnderlineThickness 16 def
  /Notice (Showboat
  1991 by David Rakowski.  Alle Rechte Vorbehalten.) readonly def
 end readonly def
 /FontName /Showboat def
 --stdin--
 ....
 
 Using this information, a possible name might be:
 
 [source,shell]
 ....
 -type1-Showboat-medium-r-normal-decorative-0-0-0-0-p-0-iso8859-1
 ....
 
 The components of our name are:
 
 Foundry::
 Lets just name all the new fonts `type1`.
 
 Family::
 The name of the font.
 
 Weight::
 Normal, bold, medium, semibold, etc.
 From the man:strings[1] output above, it appears that this font has a weight of __medium__.
 
 Slant::
 __r__oman, __i__talic, __o__blique, etc.
 Since the _ItalicAngle_ is zero, _roman_ will be used.
 
 Width::
 Normal, wide, condensed, extended, etc.
 Until it can be examined, the assumption will be __normal__.
 
 Additional style::
 Usually omitted, but this will indicate that the font contains decorative capital letters.
 
 Spacing::
 proportional or monospaced.
 _Proportional_ is used since _isFixedPitch_ is false.
 
 All of these names are arbitrary, but one should strive to be compatible with the existing conventions.
 A font is referenced by name with possible wild cards by an X11 program, so the name chosen should make some sense.
 One might begin by simply using 
 
 [source,shell]
 ....
 ...-normal-r-normal-...-p-...
 ....
 
 as the name, and then use man:xfontsel[1] to examine it and adjust the name based on the appearance of the font.
 
 So, to complete our example:
 
 [source,shell]
 ....
 Make the font accessible to X11
 % cd /usr/X11R6/lib/X11/fonts/Type1
 % ln -s /usr/local/share/fonts/type1/showboat.pfb .
 
 Edit fonts.dir and fonts.scale, adding the line describing the font
 and incrementing the number of fonts which is found on the first line.
 % ex fonts.dir
 :1p
 25
 :1c
 26
 .
 :$a
 showboat.pfb -type1-showboat-medium-r-normal-decorative-0-0-0-0-p-0-iso8859-1
 .
 :wq
 
 fonts.scale seems to be identical to fonts.dir...
 % cp fonts.dir fonts.scale
 
 Tell X11 that things have changed
 % xset fp rehash
 
 Examine the new font
 % xfontsel -pattern -type1-*
 ....
 
 References: man:xfontsel[1], man:xset[1], The X Windows System in a Nutshell, http://www.ora.com/[O'Reilly & Associates].
 
 [[type1-fonts-ghostscript]]
 == Using Type 1 Fonts with Ghostscript
 
 Ghostscript references a font via its [.filename]#Fontmap#.
 This must be modified in a similar way to the X11 [.filename]#fonts.dir#.
 Ghostscript can use either the [.filename]#.pfa# or the [.filename]#.pfb# format fonts.
 Using the font from the previous example, here is how to use it with Ghostscript:
 
 [source,shell]
 ....
 Put the font in Ghostscript's font directory
 % cd /usr/local/share/ghostscript/fonts
 % ln -s /usr/local/share/fonts/type1/showboat.pfb .
 
 Edit Fontmap so Ghostscript knows about the font
 % cd /usr/local/share/ghostscript/4.01
 % ex Fontmap
 :$a
 /Showboat        (showboat.pfb) ; % From CICA /fonts/atm/showboat
 .
 :wq
 
 Use Ghostscript to examine the font
 % gs prfont.ps
 Aladdin Ghostscript 4.01 (1996-7-10)
 Copyright (C) 1996 Aladdin Enterprises, Menlo Park, CA.  All rights
 reserved.
 This software comes with NO WARRANTY: see the file PUBLIC for details.
 Loading Times-Roman font from /usr/local/share/ghostscript/fonts/tir_____.pfb...
  /1899520 581354 1300084 13826 0 done.
 GS>Showboat DoFont
 Loading Showboat font from /usr/local/share/ghostscript/fonts/showboat.pfb...
  1939688 565415 1300084 16901 0 done.
 >>showpage, press <return> to continue<<
 >>showpage, press <return> to continue<<
 >>showpage, press <return> to continue<<
 GS>quit
 ....
 
 References: [.filename]#fonts.txt# in the Ghostscript 4.01 distribution
 
 [[type1-fonts-groff]]
 == Using Type 1 Fonts with Groff
 
 Now that the new font can be used by both X11 and Ghostscript, how can one use the new font with groff? First of all, since we are dealing with type 1 PostScript(R) fonts, the groff device that is applicable is the _ps_ device.
 A font file must be created for each font that groff can use.
 A groff font name is just a file in [.filename]#/usr/share/groff_font/devps#.
 With our example, the font file could be [.filename]#/usr/share/groff_font/devps/SHOWBOAT#.
 The file must be created using tools provided by groff.
 
 The first tool is `afmtodit`.
 This is not normally installed, so it must be retrieved from the source distribution.
 I found I had to change the first line of the file, so I did:
 
 [source,shell]
 ....
 % cp /usr/src/gnu/usr.bin/groff/afmtodit/afmtodit.pl /tmp
 % ex /tmp/afmtodit.pl
 :1c
 #!/usr/bin/perl -P-
 .
 :wq
 ....
 
 This tool will create the groff font file from the metrics file ([.filename]#.afm# suffix.)
 Continuing with our example:
 
 [source,shell]
 ....
 Many .afm files are in Mac format... ^M delimited lines
 We need to convert them to UNIX(R) style ^J delimited lines
 % cd /tmp
 % cat /usr/local/share/fonts/type1/showboat.afm |
 	tr '\015' '\012' >showboat.afm
 
 Now create the groff font file
 % cd /usr/share/groff_font/devps
 % /tmp/afmtodit.pl -d DESC -e text.enc /tmp/showboat.afm generate/textmap SHOWBOAT
 ....
 
 The font can now be referenced with the name SHOWBOAT.
 
 If Ghostscript is used to drive the printers on the system, then nothing more needs to be done.
 However, if true PostScript(R) printers are used, then the font must be downloaded to the printer in order for the font to be used (unless the printer happens to have the showboat font built in or on an accessible font disk.)
 The final step is to create a downloadable font.
 The `pfbtops` tool is used to create the [.filename]#.pfa# format of the font, and [.filename]#download# is modified to reference the new font.
 The [.filename]#download# must reference the internal name of the font.
 This can easily be determined from the groff font file as illustrated:
 
 [source,shell]
 ....
 Create the .pfa font file
 % pfbtops /usr/local/share/fonts/type1/showboat.pfb >showboat.pfa
 ....
 
 Of course, if [.filename]#.pfa# is already available, just use a symbolic link to reference it.
 
 [source,shell]
 ....
 Get the internal font name
 % fgrep internalname SHOWBOAT
 internalname Showboat
 Tell groff that the font must be downloaded
 % ex download
 :$a
 Showboat      showboat.pfa
 .
 :wq
 ....
 
 To test the font:
 
 [source,shell]
 ....
 % cd /tmp
 % cat >example.t <<EOF
 .sp 5
 .ps 16
 This is an example of the Showboat font:
 .br
 .ps 48
 .vs (\n(.s+2)p
 .sp
 .ft SHOWBOAT
 ABCDEFGHI
 .br
 JKLMNOPQR
 .br
 STUVWXYZ
 .sp
 .ps 16
 .vs (\n(.s+2)p
 .fp 5 SHOWBOAT
 .ft R
 To use it for the first letter of a paragraph, it will look like:
 .sp 50p
 \s(48\f5H\s0\fRere is the first sentence of a paragraph that uses the
 showboat font as its first letter.
 Additional vertical space must be used to allow room for the larger
 letter.
 EOF
 % groff -Tps example.t >example.ps
 
 To use ghostscript/ghostview
 % ghostview example.ps
 
 To print it
 % lpr -Ppostscript example.ps
 ....
 
 References: [.filename]#/usr/src/gnu/usr.bin/groff/afmtodit/afmtodit.man#, man:groff_font[5], man:groff_char[7], man:pfbtops[1].
 
 [[convert-truetype]]
 == Converting TrueType Fonts to a groff/PostScript Format For groff
 
 This potentially requires a bit of work, simply because it depends on some utilities that are not installed as part of the base system.
 They are:
 
 `ttf2pf`::
 TrueType to PostScript conversion utilities.
 This allows conversion of a TrueType font to an ascii font metric ([.filename]#.afm#) file.
 +
 Currently available at http://sunsite.icm.edu.pl/pub/GUST/contrib/BachoTeX98/ttf2pf/[http://sunsite.icm.edu.pl/pub/GUST/contrib/BachoTeX98/ttf2pf/].
 Note: These files are PostScript programs and must be downloaded to disk by holding down kbd:[Shift] when clicking on the link.
 Otherwise, your browser may try to launch ghostview to view them.
 +
 The files of interest are:
 
 ** [.filename]#GS_TTF.PS#
 ** [.filename]#PF2AFM.PS#
 ** [.filename]#ttf2pf.ps#
 +
 The funny upper/lower case is due to their being intended also for DOS shells.
 [.filename]#ttf2pf.ps# makes use of the others as upper case, so any renaming must be consistent with this.
 (Actually, [.filename]#GS_TTF.PS# and [.filename]#PFS2AFM.PS# are supposedly part of the Ghostscript distribution, but it is just as easy to use these as an isolated utility.
 FreeBSD does not seem to include the latter.)
 You also may want to have these installed to [.filename]#/usr/local/share/groff_font/devps#(?).
 
 `afmtodit`::
 Creates font files for use with groff from ascii font metrics file.
 This usually resides in the directory, [.filename]#/usr/src/contrib/groff/afmtodit#, and requires some work to get going.
 +
 [NOTE]
 ====
 If you are paranoid about working in the [.filename]#/usr/src# tree, simply copy the contents of the above directory to a work location.
 ====
 +
 In the work area, you will need to make the utility.
 Just type:
 +
 [source,shell]
 ....
 # make -f Makefile.sub afmtodit
 ....
 +
 You may also need to copy [.filename]#/usr/contrib/groff/devps/generate/textmap# to [.filename]#/usr/share/groff_font/devps/generate# if it does not already exist.
 
 Once all these utilities are in place, you are ready to commence:
 
 . Create [.filename]#.afm# by typing:
 +
 [source,shell]
 ....
 % gs -dNODISPLAY -q -- ttf2pf.ps TTF_name PS_font_name AFM_name
 ....
-+ 
++
 Where, _TTF_name_ is your TrueType font file, _PS_font_name_ is the file name for [.filename]#.pfa#, _AFM_name_ is the name you wish for [.filename]#.afm#. If you do not specify output file names for the [.filename]#.pfa# or [.filename]#.afm# files, then default names will be generated from the TrueType font file name.
-+ 
++
 This also produces a [.filename]#.pfa#, the ascii PostScript font metrics file ([.filename]#.pfb# is for the binary form).
 This will not be needed, but could (I think) be useful for a fontserver.
-+ 
++
 For example, to convert the 30f9 Barcode font using the default file names, use the following command:
 +
 [source,shell]
 ....
 % gs -dNODISPLAY -- ttf2pf.ps 3of9.ttf
 Aladdin Ghostscript 5.10 (1997-11-23)
 Copyright (C) 1997 Aladdin Enterprises, Menlo Park, CA.  All rights reserved.
 This software comes with NO WARRANTY: see the file PUBLIC for details.
 Converting 3of9.ttf to 3of9.pfa and 3of9.afm.
 ....
-+ 
++
 If you want the converted fonts to be stored in [.filename]#A.pfa# and [.filename]#B.afm#, then use this command:
 +
 [source,shell]
 ....
 % gs -dNODISPLAY -- ttf2pf.ps 3of9.ttf A B
 Aladdin Ghostscript 5.10 (1997-11-23)
 Copyright (C) 1997 Aladdin Enterprises, Menlo Park, CA.  All rights reserved.
 This software comes with NO WARRANTY: see the file PUBLIC for details.
 Converting 3of9.ttf to A.pfa and B.afm.
 ....
 
 . Create the groff PostScript file:
-+ 
++
 Change directories to [.filename]#/usr/share/groff_font/devps# so as to make the following command easier to execute.
 You will probably need root privileges for this.
 (Or, if you are paranoid about working there, make sure you reference the files [.filename]#DESC#, [.filename]#text.enc# and [.filename]#generate/textmap# as being in this directory.)
 +
 [source,shell]
 ....
 % afmtodit -d DESC -e text.enc file.afm generate/textmap PS_font_name
 ....
-+ 
++
 Where, [.filename]#file.afm# is the _AFM_name_ created by `ttf2pf.ps` above, and _PS_font_name_ is the font name used from that command, as well as the name that man:groff[1] will use for references to this font.
 For example, assuming you used the first `tiff2pf.ps` above, then the 3of9 Barcode font can be created using the command:
 +
 [source,shell]
 ....
 % afmtodit -d DESC -e text.enc 3of9.afm generate/textmap 3of9
 ....
-+ 
++
 Ensure that the resulting _PS_font_name_ file (e.g., [.filename]#3of9# in the example above) is located in the directory [.filename]#/usr/share/groff_font/devps# by copying or moving it there.
-+ 
++
 Note that if [.filename]#ttf2pf.ps# assigns a font name using the one it finds in the TrueType font file and you want to use a different name, you must edit the [.filename]#.afm# prior to running `afmtodit`.
 This name must also match the one used in the Fontmap file if you wish to pipe man:groff[1] into man:gs[1].
 
 [[truetype-for-other-programs]]
 == Can TrueType Fonts be Used with Other Programs?
 
 The TrueType font format is used by Windows, Windows 95, and Mac's.
 It is quite popular and there are a great number of fonts available in this format.
 
 Unfortunately, there are few applications that I am aware of that can use this format: Ghostscript and Povray come to mind.
 Ghostscript's support, according to the documentation, is rudimentary and the results are likely to be inferior to type 1 fonts.
 Povray version 3 also has the ability to use TrueType fonts, but I rather doubt many people will be creating documents as a series of raytraced pages :-).
 
 This rather dismal situation may soon change.
 The http://www.freetype.org/[FreeType Project] is currently developing a useful set of FreeType tools:
 
 * The `xfsft` font server for X11 can serve TrueType fonts in addition to regular fonts. Though currently in beta, it is said to be quite usable. See http://www.dcs.ed.ac.uk/home/jec/programs/xfsft/[Juliusz Chroboczek's page] for further information. Porting instructions for FreeBSD can be found at http://math.missouri.edu/~stephen/software/[Stephen Montgomery's software page].
 * xfstt is another font server for X11, available under link:ftp://sunsite.unc.edu/pub/Linux/X11/fonts/[ftp://sunsite.unc.edu/pub/Linux/X11/fonts/].
 * A program called `ttf2bdf` can produce BDF files suitable for use in an X environment from TrueType files. Linux binaries are said to be available from link:ftp://crl.nmsu.edu/CLR/multiling/General/[ftp://crl.nmsu.edu/CLR/multiling/General/].
 * and others ...
 
 [[obtaining-additional-fonts]]
 == Where Can Additional Fonts be Obtained?
 
 Many fonts are available on the Internet.
 They are either entirely free, or are share-ware.
 In addition many fonts are available in the [.filename]#x11-fonts/# category in the ports collection
 
 [[additional-questions]]
 == Additional Questions
 
 * What use are the [.filename]#.pfm# files?
 * Can one generate the [.filename]#.afm# from a [.filename]#.pfa# or [.filename]#.pfb#?
 * How to generate the groff character mapping files for PostScript fonts with non-standard character names?
 * Can xditview and devX?? devices be set up to access all the new fonts?
 * It would be good to have examples of using TrueType fonts with Povray and Ghostscript.
diff --git a/documentation/content/en/articles/freebsd-questions/_index.adoc b/documentation/content/en/articles/freebsd-questions/_index.adoc
index 1edcd2ecf0..ba81c5ce28 100644
--- a/documentation/content/en/articles/freebsd-questions/_index.adoc
+++ b/documentation/content/en/articles/freebsd-questions/_index.adoc
@@ -1,269 +1,269 @@
 ---
 title: How to get Best Results from the FreeBSD-questions Mailing List
 authors:
   - author: Greg Lehey
     email: grog@FreeBSD.org
 description: How to get Best Results from the FreeBSD-questions Mailing List
 trademarks: ["freebsd", "microsoft", "opengroup", "qualcomm", "general"]
 tags: ["questions", "mailing", "FreeBSD"]
 ---
 
 = How to get Best Results from the FreeBSD-questions Mailing List
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 ifeval::["{backend}" == "html5"]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/urls.adoc[]
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
 [.abstract-title]
 Abstract
 
 This document provides useful information for people looking to prepare an e-mail to the FreeBSD-questions mailing list.
 Advice and hints are given that will maximize the chance that the reader will receive useful replies.
 
 This document is regularly posted to the FreeBSD-questions mailing list.
 
 '''
 
 toc::[]
 
 == Introduction
 
 `FreeBSD-questions` is a mailing list maintained by the FreeBSD project to help people who have questions about the normal use of FreeBSD.
 Another group, `FreeBSD-hackers`, discusses more advanced questions such as future development work.
 
 [NOTE]
 ====
 The term "hacker" has nothing to do with breaking into other people's computers.
 The correct term for the latter activity is "cracker", but the popular press has not found out yet.
 The FreeBSD hackers disapprove strongly of cracking security, and have nothing to do with it.
 For a longer description of hackers, see Eric Raymond's http://www.catb.org/~esr/faqs/hacker-howto.html[How To Become A Hacker]
 ====
 
 This is a regular posting aimed to help both those seeking advice from FreeBSD-questions (the "newcomers"), and also those who answer the questions (the "hackers").
 
 Inevitably there is some friction, which stems from the different viewpoints of the two groups.
 The newcomers accuse the hackers of being arrogant, stuck-up, and unhelpful, while the hackers accuse the newcomers of being stupid, unable to read plain English, and expecting everything to be handed to them on a silver platter.
 Of course, there is an element of truth in both these claims, but for the most part these viewpoints come from a sense of frustration.
 
 In this document, I would like to do something to relieve this frustration and help everybody get better results from FreeBSD-questions.
 In the following section, I recommend how to submit a question; after that, we will look at how to answer one.
 
 == How to Subscribe to FreeBSD-questions
 
 FreeBSD-questions is a mailing list, so you need mail access.
 Point your WWW browser to the {freebsd-questions}.
 In the section titled "Subscribing to freebsd-questions" fill in the "Your email address" field; the other fields are optional.
 
 [NOTE]
 ====
 The password fields in the subscription form provide only mild security, but should prevent others from messing with your subscription.
 _Do not use a valuable password_ as it will occasionally be emailed back to you in cleartext.
 ====
 
 You will receive a confirmation message from mailman; follow the included instructions to complete your subscription.
 
 Finally, when you get the "Welcome" message from mailman telling you the details of the list and subscription area password, __please save it__.
 If you ever should want to leave the list, you will need the information there.
 See the next section for more details.
 
 == How to Unsubscribe from FreeBSD-questions
 
 When you subscribed to FreeBSD-questions, you got a welcome message from mailman.
 In this message, amongst other things, it told you how to unsubscribe.
 Here is a typical message:
 
 ....
 Welcome to the
       freebsd-questions@freebsd.org mailing list!
 
 To post to this list, send your email to:
 
   freebsd-questions@freebsd.org
 
 General information about the mailing list is at:
 
   https://lists.freebsd.org/mailman/listinfo/freebsd-questions
 
 If you ever want to unsubscribe or change your options (e.g., switch to
 or from digest mode, change your password, etc.), visit your
 subscription page at:
 
 https://lists.freebsd.org/mailman/options/freebsd-questions/grog%40lemsi.de
 
 You can also make such adjustments via email by sending a message to:
 
   freebsd-questions-request@freebsd.org
 
 with the word 'help' in the subject or body (do not include the
 quotes), and you will get back a message with instructions.
 
 You must know your password to change your options (including changing
 the password, itself) or to unsubscribe.  It is:
 
   12345
 
 Normally, Mailman will remind you of your freebsd.org mailing list
 passwords once every month, although you can disable this if you
 prefer.  This reminder will also include instructions on how to
 unsubscribe or change your account options.  There is also a button on
 your options page that will email your current password to you.
 ....
 
 From the URL specified in your "Welcome" message you may visit the "Account management page" and enter a request to "Unsubscribe" you from FreeBSD-questions mailing list.
 
 A confirmation message will be sent to you from mailman; follow the included instructions to finish unsubscribing.
 
 If you have done this, and you still cannot figure out what is going on, send a message to mailto:freebsd-questions-request@FreeBSD.org[freebsd-questions-request@FreeBSD.org], and they will sort things out for you.
 _Do not_ send a message to FreeBSD-questions: they cannot help you.
 
 == Should I ask `-questions` or `-hackers`?
 
 Two mailing lists handle general questions about FreeBSD, `FreeBSD-questions` and `FreeBSD-hackers`.
 In some cases, it is not really clear which group you should ask.
 The following criteria should help for 99% of all questions, however:
 
 . If the question is of a general nature, ask `FreeBSD-questions`. Examples might be questions about installing FreeBSD or the use of a particular UNIX(R) utility.
 . If you think the question relates to a bug, but you are not sure, or you do not know how to look for it, send the message to `FreeBSD-questions`.
 . If the question relates to a bug, and you are _sure_ that it is a bug (for example, you can pinpoint the place in the code where it happens, and you maybe have a fix), then send the message to `FreeBSD-hackers`.
 . If the question relates to enhancements to FreeBSD, and you can make suggestions about how to implement them, then send the message to `FreeBSD-hackers`.
 
 There are also a number of other link:{handbook}#eresources-mail[specialized mailing lists], which caters to more specific interests.
 The criteria above still apply, and it is in your interest to stick to them, since you are more likely to get good results that way.
 
 == Before Submitting a Question
 
 You can (and should) do some things yourself before asking a question on one of the mailing lists:
 
 * Try solving the problem on your own. If you post a question which shows that you have tried to solve the problem, your question will generally attract more positive attention from people reading it. Trying to solve the problem yourself will also enhance your understanding of FreeBSD, and will eventually let you use your knowledge to help others by answering questions posted to the mailing lists.
 * Read the manual pages, and the FreeBSD documentation (either installed in [.filename]#/usr/doc# or accessible via WWW at http://www.FreeBSD.org[http://www.FreeBSD.org]), especially the link:{handbook}[handbook] and the link:{faq}[FAQ].
 * Browse and/or search the archives for the mailing list, to see if your question or a similar one has been asked (and possibly answered) on the list. You can browse and/or search the mailing list archives at https://www.FreeBSD.org/mail[https://www.FreeBSD.org/mail] and https://www.FreeBSD.org/search/#mailinglists[https://www.FreeBSD.org/search/#mailinglists] respectively. This can be done at other WWW sites as well, for example at http://marc.theaimsgroup.com[http://marc.theaimsgroup.com].
 * Use a search engine such as http://www.google.com[Google] or http://www.yahoo.com[Yahoo] to find answers to your question.
 
 == How to Submit a Question
 
 When submitting a question to FreeBSD-questions, consider the following points:
 
 * Remember that nobody gets paid for answering a FreeBSD question. They do it of their own free will. You can influence this free will positively by submitting a well-formulated question supplying as much relevant information as possible. You can influence this free will negatively by submitting an incomplete, illegible, or rude question. It is perfectly possible to send a message to FreeBSD-questions and not get an answer even if you follow these rules. It is much more possible to not get an answer if you do not. In the rest of this document, we will look at how to get the most out of your question to FreeBSD-questions.
 * Not everybody who answers FreeBSD questions reads every message: they look at the subject line and decide whether it interests them. Clearly, it is in your interest to specify a subject. "FreeBSD problem" or "Help" are not enough. If you provide no subject at all, many people will not bother reading it. If your subject is not specific enough, the people who can answer it may not read it.
 * Format your message so that it is legible, and PLEASE DO NOT SHOUT!!!!!. We appreciate that a lot of people do not speak English as their first language, and we try to make allowances for that, but it is really painful to try to read a message written full of typos or without any line breaks.
-+ 
++
 Do not underestimate the effect that a poorly formatted mail message has, not just on the FreeBSD-questions mailing list.
 Your mail message is all people see of you, and if it is poorly formatted, one line per paragraph, badly spelt, or full of errors, it will give people a poor impression of you.
-+ 
++
 A lot of badly formatted messages come from http://www.lemis.com/email.html[bad mailers or badly configured mailers].
 The following mailers are known to send out badly formatted messages without you finding out about them:
 
 ** Eudora(R)
 ** exmh
 ** Microsoft(R) Exchange
 ** Microsoft(R) Outlook(R)
-+ 
++
 Try not to use MIME: a lot of people use mailers which do not get on very well with MIME.
 * Make sure your time and time zone are set correctly. This may seem a little silly, since your message still gets there, but many of the people you are trying to reach get several hundred messages a day. They frequently sort the incoming messages by subject and by date, and if your message does not come before the first answer, they may assume they missed it and not bother to look.
 * Do not include unrelated questions in the same message. Firstly, a long message tends to scare people off, and secondly, it is more difficult to get all the people who can answer all the questions to read the message.
 * Specify as much information as possible. This is a difficult area, and we need to expand on what information you need to submit, but here is a start:
 
 ** In nearly every case, it is important to know the version of FreeBSD you are running. This is particularly the case for FreeBSD-CURRENT, where you should also specify the date of the sources, though of course you should not be sending questions about -CURRENT to FreeBSD-questions.
 ** With any problem which _could_ be hardware related, tell us about your hardware. In case of doubt, assume it is possible that it is hardware. What kind of CPU are you using? How fast? What motherboard? How much memory? What peripherals?
-+ 
++
 There is a judgement call here, of course, but the output of the man:dmesg[8] command can frequently be very useful, since it tells not just what hardware you are running, but what version of FreeBSD as well.
 ** If you get error messages, do not say "I get error messages", say (for example) "I get the error message 'No route to host'".
 ** If your system panics, do not say "My system panicked", say (for example) "my system panicked with the message 'free vnode isn't'".
 ** If you have difficulty installing FreeBSD, please tell us what hardware you have. In particular, it is important to know the IRQs and I/O addresses of the boards installed in your machine.
 ** If you have difficulty getting PPP to run, describe the configuration. Which version of PPP do you use? What kind of authentication do you have? Do you have a static or dynamic IP address? What kind of messages do you get in the log file?
 
 * A lot of the information you need to supply is the output of programs, such as man:dmesg[8], or console messages, which usually appear in [.filename]#/var/log/messages#. Do not try to copy this information by typing it in again; it is a real pain, and you are bound to make a mistake. To send log file contents, either make a copy of the file and use an editor to trim the information to what is relevant, or cut and paste into your message. For the output of programs like man:dmesg[8], redirect the output to a file and include that. For example,
 +
 [source,shell]
 ....
 % dmesg > /tmp/dmesg.out
 ....
-+ 
++
 This redirects the information to the file [.filename]#/tmp/dmesg.out#.
 * If you do all this, and you still do not get an answer, there could be other reasons. For example, the problem is so complicated that nobody knows the answer, or the person who does know the answer was offline. If you do not get an answer after, say, a week, it might help to re-send the message. If you do not get an answer to your second message, though, you are probably not going to get one from this forum. Resending the same message again and again will only make you unpopular.
 
 To summarize, let's assume you know the answer to the following question (yes, it is the same one in each case).
 You choose which of these two questions you would be more prepared to answer:
 
 .Message 1
 [example]
 ====
 
 ....
 Subject: HELP!!?!??
 I just can't get hits damn silly FereBSD system to
 workd, and Im really good at this tsuff, but I have never seen
 anythign sho difficult to install, it jst wont work whatever I try
 so why don't you guys tell me what I doing wrong.
 ....
 ====
 
 .Message 2
 [example]
 ====
 
 ....
 Subject: Problems installing FreeBSD
 
 I've just got the FreeBSD 2.1.5 CDROM from Walnut Creek, and I'm having a lot
 of difficulty installing it.  I have a 66 MHz 486 with 16 MB of
 memory and an Adaptec 1540A SCSI board, a 1.2GB Quantum Fireball
 disk and a Toshiba 3501XA CDROM drive.  The installation works just
 fine, but when I try to reboot the system, I get the message
 Missing Operating System.
 ....
 ====
 
 == How to Follow up to a Question
 
 Often you will want to send in additional information to a question you have already sent.
 The best way to do this is to reply to your original message.
 This has three advantages:
 
 . You include the original message text, so people will know what you are talking about. Do not forget to trim unnecessary text out, though.
 . The text in the subject line stays the same (you did remember to put one in, did you not?). Many mailers will sort messages by subject. This helps group messages together.
 . The message reference numbers in the header will refer to the previous message. Some mailers, such as http://www.mutt.org/[mutt], can _thread_ messages, showing the exact relationships between the messages.
 
 == How to Answer a Question
 
 Before you answer a question to FreeBSD-questions, consider:
 
 . A lot of the points on submitting questions also apply to answering questions. Read them.
 . Has somebody already answered the question? The easiest way to check this is to sort your incoming mail by subject: then (hopefully) you will see the question followed by any answers, all together.
-+ 
++
 If somebody has already answered it, it does not automatically mean that you should not send another answer.
 But it makes sense to read all the other answers first.
 . Do you have something to contribute beyond what has already been said? In general, "Yeah, me too" answers do not help much, although there are exceptions, like when somebody is describing a problem they are having, and they do not know whether it is their fault or whether there is something wrong with the hardware or software. If you do send a "me too" answer, you should also include any further relevant information.
 . Are you sure you understand the question? Very frequently, the person who asks the question is confused or does not express themselves very well. Even with the best understanding of the system, it is easy to send a reply which does not answer the question. This does not help: you will leave the person who submitted the question more frustrated or confused than ever. If nobody else answers, and you are not too sure either, you can always ask for more information.
 . Are you sure your answer is correct? If not, wait a day or so. If nobody else comes up with a better answer, you can still reply and say, for example, "I do not know if this is correct, but since nobody else has replied, why don't you try replacing your ATAPI CDROM with a frog?".
 . Unless there is a good reason to do otherwise, reply to the sender and to FreeBSD-questions. Many people on the FreeBSD-questions are "lurkers": they learn by reading messages sent and replied to by others. If you take a message which is of general interest off the list, you are depriving these people of their information. Be careful with group replies; lots of people send messages with hundreds of CCs. If this is the case, be sure to trim the Cc: lines appropriately.
 . Include relevant text from the original message. Trim it to the minimum, but do not overdo it. It should still be possible for somebody who did not read the original message to understand what you are talking about.
 . Use some technique to identify which text came from the original message, and which text you add. I personally find that prepending "`>`" to the original message works best. Leaving white space after the "`> ;`" and leave empty lines between your text and the original text both make the result more readable.
 . Put your response in the correct place (after the text to which it replies). It is very difficult to read a thread of responses where each reply comes before the text to which it replies.
 . Most mailers change the subject line on a reply by prepending a text such as "Re: ". If your mailer does not do it automatically, you should do it manually.
 . If the submitter did not abide by format conventions (lines too long, inappropriate subject line) _please_ fix it. In the case of an incorrect subject line (such as "HELP!!??"), change the subject line to (say) "Re: Difficulties with sync PPP (was: HELP!!??)". That way other people trying to follow the thread will have less difficulty following it.
-+ 
++
 In such cases, it is appropriate to say what you did and why you did it, but try not to be rude.
 If you find you can not answer without being rude, do not answer.
-+ 
++
 If you just want to reply to a message because of its bad format, just reply to the submitter, not to the list.
 You can just send him this message in reply, if you like.
diff --git a/documentation/content/en/articles/freebsd-releng/_index.adoc b/documentation/content/en/articles/freebsd-releng/_index.adoc
index 728ec196c6..d133116fae 100644
--- a/documentation/content/en/articles/freebsd-releng/_index.adoc
+++ b/documentation/content/en/articles/freebsd-releng/_index.adoc
@@ -1,864 +1,864 @@
 ---
 title: FreeBSD Release Engineering
 authors:
   - author: Glen Barber
     email: gjb@FreeBSD.org
 organizations:
   - organization: The FreeBSD Foundation
     webpage: https://www.freebsdfoundation.org/
   - organization: Rubicon Communications, LLC (Netgate)
     webpage: https://www.netgate.com/
 description: Describes the approach used by the FreeBSD release engineering team to make production quality releases of the FreeBSD Operating System. It describes the tools available for those interested in producing customized FreeBSD releases for corporate rollouts or commercial productization
 trademarks: ["freebsd", "intel", "general"]
 tags: ["releases", "engineering", "process", "FreeBSD"]
 ---
 
 = FreeBSD Release Engineering
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :teamBugmeister: FreeBSD Bugmeister Team
 :teamDoceng: FreeBSD Documentation Engineering Team
 :teamPortmgr: FreeBSD Ports Management Team
 :teamPostmaster: FreeBSD Postmaster Team
 :teamRe: FreeBSD Release Engineering Team
 :teamSecteam: FreeBSD Security Team
 :branchHead: head/
 :branchStable: stable/
 :branchStablex: stable/12/
 :branchReleng: releng/
 :branchRelengx: releng/12.0/
 :branchReleasex: release/12.0.0/
 :branchRevision: 12.0
 
 [.abstract-title]
 Abstract
 
 This article describes the release engineering process of the FreeBSD Project.
 
 '''
 
 toc::[]
 
 [[introduction]]
 == Introduction to the FreeBSD Release Engineering Process
 
 Development of FreeBSD has a very specific workflow.
 In general, all changes to the FreeBSD base system are committed to the  {branchHead} branch, which reflects the top of the source tree.
 
 After a reasonable testing period, changes can then be merged to the {branchStable} branches.
 The default minimum timeframe before merging to {branchStable} branches is three (3) days.
 
 Although a general rule to wait a minimum of three days before merging from {branchHead}, there are a few special circumstances where an immediate merge may be necessary, such as a critical security fix, or a bug fix that directly inhibits the release build process.
 
 After several months, and the number of changes in the {branchStable} branch have grown significantly, it is time to release the next version of FreeBSD. 
 These releases have been historically referred to as "point" releases.
 
 In between releases from the {branchStable} branches, approximately every two (2) years, a release will be cut directly from {branchHead}.
 These releases have been historically referred to as "dot-zero" releases.
 
 This article will highlight the workflow and responsibilities of the {teamRe} for both "dot-zero" and "point"' releases.
 
 The following sections of this article describe:
 
 <<releng-prep>>::
 General information and preparation before starting the release cycle.
 
 <<releng-website>>::
 Website Changes During the Release Cycle
 
 <<releng-terms>>::
 Terminology and general information, such as the "code slush" and "code freeze", used throughout this document.
 
 <<releng-head>>::
 The Release Engineering process for a "dot-zero" release.
 
 <<releng-stable>>::
 The Release Engineering process for a "point" release.
 
 <<releng-building>>::
 Information related to the specific procedures to build installation medium.
 
 <<releng-mirrors>>::
 Procedures to publish installation medium.
 
 <<releng-wrapup>>::
 Wrapping up the release cycle.
 
 [[releng-prep]]
 == General Information and Preparation
 
 Approximately two months before the start of the release cycle, the {teamRe} decides on a schedule for the release.
 The schedule includes the various milestone points of the release cycle, such as freeze dates, branch dates, and build dates.
 For example:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | Milestone
 | Anticipated Date
 
 |{branchHead} slush:
 |May 27, 2016
 
 |{branchHead} freeze:
 |June 10, 2016
 
 |{branchHead} KBI freeze:
 |June 24, 2016
 
 |`doc/` tree slush [1]:
 |June 24, 2016
 
 |Ports quarterly branch [2]:
 |July 1, 2016
 
 |{branchStablex} branch:
 |July 8, 2016
 
 |`doc/` tree tag [3]:
 |July 8, 2016
 
 |BETA1 build starts:
 |July 8, 2016
 
 |{branchHead} thaw:
 |July 9, 2016
 
 |BETA2 build starts:
 |July 15, 2016
 
 |BETA3 build starts [*]:
 |July 22, 2016
 
 |{branchRelengx} branch:
 |July 29, 2016
 
 |RC1 build starts:
 |July 29, 2016
 
 |{branchStablex} thaw:
 |July 30, 2016
 
 |RC2 build starts:
 |August 5, 2016
 
 |Final Ports package builds [4]:
 |August 6, 2016
 
 |Ports release tag:
 |August 12, 2016
 
 |RC3 build starts [*]:
 |August 12, 2016
 
 |RELEASE build starts:
 |August 19, 2016
 
 |RELEASE announcement:
 |September 2, 2016
 |===
 
 [NOTE]
 ====
 Items marked with "[*]" are "as needed".
 ====
 
 . The `doc/` tree slush is coordinated by the {teamDoceng}.
 . The Ports quarterly branch used is determined by when the final `RC` build is planned. A new quarterly branch is created on the first day of the quarter, so this metric should be used when taking the release cycle milestones into account. The quarterly branch is created by the {teamPortmgr}.
 . The `doc/` tree is tagged by the {teamDoceng}.
 . The final Ports package build is done by the {teamPortmgr} after the final (or what is expected to be final) `RC` build.
 
 [NOTE]
 ====
 If the release is being created from an existing {branchStable} branch, the KBI freeze date can be excluded, since the KBI is already considered frozen on established {branchStable} branches.
 ====
 
 When writing the release cycle schedule, a number of things need to be taken into consideration, in particular milestones where the target date depends on predefined milestones upon which there is a dependency.
 For example, the Ports Collection release tag originates from the active quarterly branch at the time of the last `RC`.
 This in part defines which quarterly branch is used, when the release tag can happen, and what revision of the ports tree is used for the final `RELEASE` build.
 
 After general agreement on the schedule, the {teamRe} emails the schedule to the FreeBSD Developers.
 
 It is somewhat typical that many developers will inform the {teamRe} about various works-in-progress.
 In some cases, an extension for the in-progress work will be requested, and in other cases, a request for "blanket approval" to a particular subset of the tree will be made.
 
 When such requests are made, it is important to make sure timelines (even if estimated) are discussed.
 For blanket approvals, the length of time for the blanket approval should be made clear.
 For example, a FreeBSD developer may request blanket approvals from the start of the code slush until the start of the `RC` builds.
 
 [NOTE]
 ====
 In order to keep track of blanket approvals, the {teamRe} uses an internal repository to keep a running log of such requests, which defines the area upon which a blanket approval was granted, the author(s), when the blanket approval expires, and the reason the approval was granted.
 One example of this is granting blanket approval to [.filename]#release/doc/# to all {teamRe} members until the final `RC` to update the release notes and other release-related documentation.
 ====
 
 [NOTE]
 ====
 The {teamRe} also uses this repository to track pending approval requests that are received just prior to starting various builds during the release cycle, which the Release Engineer specifies the cutoff period with an email to the FreeBSD developers.
 ====
 
 Depending on the underlying set of code in question, and the overall impact the set of code has on FreeBSD as a whole, such requests may be approved or denied by the {teamRe}.
 
 The same applies to work-in-progress extensions.
 For example, in-progress work for a new device driver that is otherwise isolated from the rest of the tree may be granted an extension.
 A new scheduler, however, may not be feasible, especially if such dramatic changes do not exist in another branch.
 
 The schedule is also added to the Project website, in the `doc/` repository, in [.filename]#~/website/content/en/releases/{branchRevision}R/schedule.adoc#. This file is continuously updated as the release cycle progresses.
 
 [NOTE]
 ====
 In most cases, the [.filename]#schedule.adoc# can be copied from a prior release and updated accordingly.
 ====
 
 In addition to adding [.filename]#schedule.adoc# to the website, [.filename]#~/shared/releases.adoc# is also updated to add the link to the schedule to various subpages, as well as enabling the link to the schedule on the Project website index page.
 
 The schedule is also linked from [.filename]#~/website/content/en/releng/_index.adoc#.
 
 Approximately one month prior to the scheduled "code slush", the {teamRe} sends a reminder email to the FreeBSD Developers.
 
 [[releng-terms]]
 == Release Engineering Terminology
 
 This section describes some of the terminology used throughout the rest of this document.
 
 [[releng-terms-code-slush]]
 === The Code Slush
 
 Although the code slush is not a hard freeze on the tree, the {teamRe} requests that bugs in the existing code base take priority over new features.
 
 The code slush does not enforce commit approvals to the branch.
 
 [[releng-terms-code-freeze]]
 === The Code Freeze
 
 The code freeze marks the point in time where all commits to the branch require explicit approval from the {teamRe}.
 
 The FreeBSD Subversion repository contains several hooks to perform sanity checks before any commit is actually committed to the tree.
 One of these hooks will evaluate if committing to a particular branch requires specific approval.
 
 To enforce commit approvals by the {teamRe}, the Release Engineer updates [.filename]#base/svnadmin/conf/approvers#, and commits the change back to the repository.
 Once this is done, any change to the branch must include an "Approved by:" line in the commit message.
 
 The "Approved by:" line must match the second column in [.filename]#base/svnadmin/conf/approvers#, otherwise the commit will be rejected by the repository hooks.
 
 [NOTE]
 ====
 During the code freeze, FreeBSD committers are urged to follow the link:https://wiki.freebsd.org/Releng/ChangeRequestGuidelines[Change Request Guidelines].
 ====
 
 [[releng-terms-kbi-freeze]]
 === The KBI/KPI Freeze
 
 KBI/KPI stability implies that the caller of a function across two different releases of software that implement the function results in the same end state.
 The caller, whether it is a process, thread, or function, expects the function to operate in a certain way, otherwise the KBI/KPI stability on the branch is broken.
 
 [[releng-website]]
 == Website Changes During the Release Cycle
 
 This section describes the changes to the website that should occur as the release cycle progresses.
 
 [NOTE]
 ====
 The files specified throughout this section are relative to the `head/` branch of the `doc` repository in Subversion.
 ====
 
 [[releng-website-prerelease]]
 === Website Changes Before the Release Cycle Begins
 
 When the release cycle schedule is available, these files need to be updated to enable various different functionalities on the FreeBSD Project website:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#~/shared/releases.adoc#
 |Change `beta-upcoming` from `IGNORE` to `INCLUDE`
 
 |[.filename]#~/shared/releases.adoc#
 |Change `beta-testing` from `IGNORE` to `INCLUDE`
 
 |===
 
 [[releng-website-beta-rc]]
 === Website Changes During `BETA` or `RC`
 
 When transitioning from `PRERELEASE` to `BETA`, these files need to be updated to enable the "Help Test" block on the download page. All files are relative to [.filename]#head/# in the `doc` repository:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#share/releases.adoc#
 |Update `betarel-vers` to `BETA__1__`
 
 |[.filename]#~/website/data/en/news.toml#
 |Add an entry announcing the `BETA`
 
 |[.filename]#~/website/static/security/advisory-template.txt#
 |Add the new `BETA`, `RC`, or final `RELEASE` to the template
 
 |[.filename]#~/website/static/security/errata-template.txt#
 |Add the new `BETA`, `RC`, or final `RELEASE` to the template
 |===
 
 Once the {branchRelengx} branch is created, the various release-related documents need to be generated and manually added to the `doc/` repository.
 
 Within [.filename]#release/doc#, invoke to generate [.filename]#errata.html#, [.filename]#hardware.html#, [.filename]#readme.html#, and [.filename]#relnotes.html# pages, which are then added to [.filename]#doc/head/en_US.ISO8859-1/htdocs/releases/X.YR/#, where _X.Y_ represents the major and minor version number of the release.
 
 The `fbsd:nokeywords` property must be set to `on` on the newly-added files before the pre-commit hooks will allow them to be added to the repository.
 
 [NOTE]
 ====
 The relevant release-related documents exist in the [.filename]#doc# repository for FreeBSD 12.x and later.
 ====
 
 [[releng-ports-beta-rc]]
 === Ports Changes During `BETA`, `RC`, and the Final `RELEASE`
 
 For each build during the release cycle, the `MANIFEST` files containing the `SHA256` of the various distribution sets, such as `base.txz`, `kernel.txz`, and so on, are added to the package:misc/freebsd-release-manifests[] port.
 This allows utilities other than , such as package:ports-mgmt/poudriere[], to safely use these distribution sets by providing a mechanism through which the checksums can be verified.
 
 [[releng-head]]
 == Release from {branchHead}
 
 This section describes the general procedures of the FreeBSD release cycle from the {branchHead} branch.
 
 [[releng-head-builds-alpha]]
 === FreeBSD "`ALPHA`" Builds
 
 Starting with the FreeBSD 10.0-RELEASE cycle, the notion of "`ALPHA`" builds was introduced.
 Unlike the `BETA` and `RC` builds, `ALPHA` builds are not included in the FreeBSD Release schedule.
 
 The idea behind `ALPHA` builds is to provide regular FreeBSD-provided builds before the creation of the {branchStable} branch.
 
 FreeBSD `ALPHA` snapshots should be built approximately once a week.
 
 For the first `ALPHA` build, the `BRANCH` value in [.filename]#sys/conf/newvers.sh# needs to be changed from `CURRENT` to `ALPHA1`.
 For subsequent `ALPHA` builds, increment each `ALPHA__N__` value by one.
 
 See <<releng-building>> for information on building the `ALPHA` images.
 
 [[releng-head-branching]]
 === Creating the {branchStablex} Branch
 
 When creating the {branchStable} branch, several changes are required in both the new {branchStable} branch and the {branchHead} branch.
 The files listed are relative to the repository root.
 To create the new {branchStablex} branch in Subversion:
 
 [source,shell,subs="attributes"]
 ....
 % svn cp ^/head {branchStablex}
 ....
 
 Once the {branchStablex} branch has been committed, make the following edits:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#stable/12/UPDATING#
 |Update the FreeBSD version, and remove the notice about `WITNESS`
 
 |[.filename]#stable/12/contrib/jemalloc/include/jemalloc/jemalloc_FreeBSD.h#
 a|
 
 [source,shell,subs="attributes"]
 ....
 #ifndef MALLOC_PRODUCTION
 #define MALLOC_PRODUCTION
 #endif
 ....
 
 |[.filename]#stable/12/lib/clang/llvm.build.mk#
 |Uncomment `-DNDEBUG`
 
 |[.filename]#stable/12/sys/\*/conf/GENERIC*#
 |Remove debugging support
 
 |[.filename]#stable/12/sys/*/conf/MINIMAL#
 |Remove debugging support
 
 |[.filename]#stable/12/release/release.conf.sample#
 |Update `SRCBRANCH`
 
 |[.filename]#stable/12/sys/*/conf/GENERIC-NODEBUG#
 |Remove these kernel configurations
 
 |[.filename]#stable/12/sys/arm/conf/std.arm*#
 |Remove debugging options
 
 |[.filename]#stable/12/sys/conf/newvers.sh#
 |Update the `BRANCH` value to reflect `BETA1`
 
 |[.filename]#stable/12/shared/mk/src.opts.mk#
 |Move `REPRODUCIBLE_BUILD` from `\__DEFAULT_NO_OPTIONS` to `__DEFAULT_YES_OPTIONS`
 
 |[.filename]#stable/12/shared/mk/src.opts.mk#
 |Move `LLVM_ASSERTIONS` from `\__DEFAULT_YES_OPTIONS` to `__DEFAULT_NO_OPTIONS` (FreeBSD 13.x and later only)
 
 |[.filename]#stable/12/libexec/rc/rc.conf#
 |Set `dumpdev` from `AUTO` to `NO` (it is configurable via for those that want it enabled by default)
 
 |[.filename]#stable/12/release/Makefile#
 |Remove the `debug.witness.trace` entries
 |===
 
 Then in the {branchHead} branch, which will now become a new major version:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#head/UPDATING#
 |Update the FreeBSD version
 
 |[.filename]#head/sys/conf/newvers.sh#
 |Update the `BRANCH` value to reflect `CURRENT`, and increment `REVISION`
 
 |[.filename]#head/Makefile.inc1#
 |Update `TARGET_TRIPLE` and `MACHINE_TRIPLE`
 
 |[.filename]#head/sys/sys/param.h#
 |Update `__FreeBSD_version`
 
 |[.filename]#head/gnu/usr.bin/cc/cc_tools/freebsd-native.h#
 |Update `FBSD_MAJOR` and `FBSD_CC_VER`
 
 |[.filename]#head/contrib/gcc/config.gcc#
 |Append the `freebsdversion.h` section
 
 |[.filename]#head/lib/clang/llvm.build.mk#
 |Update the value of `OS_VERSION`
 
 |[.filename]#head/lib/clang/freebsd_cc_version.h#
 |Update `FREEBSD_CC_VERSION`
 
 |[.filename]#head/lib/clang/include/lld/Common/Version.inc#
 |Update `LLD_REVISION_STRING`
 
 |[.filename]#head/Makefile.libcompat#
 |Update `LIB32CPUFLAGS`
 |===
 
 [[releng-stable]]
 == Release from {branchStable}
 
 This section describes the general procedures of the FreeBSD release cycle from an extablished {branchStable} branch.
 
 [[releng-stable-slush]]
 === FreeBSD `stable` Branch Code Slush
 
 In preparation for the code freeze on a `stable` branch, several files need to be updated to reflect the release cycle is officially in progress.
 These files are all relative to the top-most level of the stable branch:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#sys/conf/newvers.sh#
 |Update the `BRANCH` value to reflect `PRERELEASE`
 
 |[.filename]#Makefile.inc1#
 |Update `TARGET_TRIPLE`
 
 |[.filename]#lib/clang/llvm.build.mk#
 |Update `OS_VERSION`
 
 |[.filename]#Makefile.libcompat#
 |Update `LIB32CPUFLAGS`
 
 |[.filename]#gnu/usr.bin/groff/tmac/mdoc.local.in#
 |Add a new `.ds` entry for the FreeBSD version, and update `doc-default-operating-system` (FreeBSD 11.x and earlier only)
 |===
 
 [[releng-stable-builds-beta]]
 === FreeBSD `BETA` Builds
 
 Following the code slush, the next phase of the release cycle is the code freeze.
 This is the point at which all commits to the stable branch require explicit approval from the {teamRe}.
 This is enforced by pre-commit hooks in the Subversion repository by editing [.filename]#base/svnadmin/conf/approvers# to include a regular expression matching the {branchStablex} branch for the release:
 
 [.programlisting,subs="attributes"]
 ....
 ^/{branchStablex}	re
 ^/{branchRelengx}	re
 ....
 
 [NOTE]
 ====
 There are two general exceptions to requiring commit approval during the release cycle.
 The first is any change that needs to be committed by the Release Engineer in order to proceed with the day-to-day workflow of the release cycle, the other is security fixes that may occur during the release cycle.
 ====
 
 Once the code freeze is in effect, the next build from the branch is labeled `BETA1`.
 This is done by updating the `BRANCH` value in [.filename]#sys/conf/newvers.sh# from `PRERELEASE` to `BETA1`.
 
 Once this is done, the first set of `BETA` builds are started.
 Subsequent `BETA` builds do not require updates to any files other than [.filename]#sys/conf/newvers.sh#, incrementing the `BETA` build number.
 
 [[releng-stable-branching]]
 === Creating the {branchRelengx} Branch
 
 When the first `RC` (Release Candidate) build is ready to begin, the {branchReleng} branch is created.
 This is a multi-step process that must be done in a specific order, in order to avoid anomalies such as overlaps with `__FreeBSD_version` values, for example.
 The paths listed below are relative to the repository root.
 The order of commits and what to change are:
 
 [source,shell,subs="attributes"]
 ....
 % svn cp ^/{branchStablex} {branchRelengx}
 ....
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#releng/12.0/sys/conf/newvers.sh#
 |Change `BETA__X__` to `RC1`
 
 |[.filename]#releng/12.0/sys/sys/param.h#
 |Update `__FreeBSD_version`
 
 |[.filename]#releng/12.0/etc/pkg/FreeBSD.conf#
 |Replace `latest` with `quarterly` as the default package repository location
 
 |[.filename]#releng/12.0/release/pkg_repos/release-dvd.conf#
 |Replace `latest` with `quarterly` as the default package repository location
 
 |[.filename]#stable/12/sys/conf/newvers.sh#
 |Update `BETA__X__` with `PRERELEASE`
 
 |[.filename]#stable/12/sys/sys/param.h#
 |Update `__FreeBSD_version`
 
 |[.filename]#svnadmin/conf/approvers#
 |Add a new approvers line for the releng branch as was done for the stable branch
 |===
 
 [source,shell,subs="attributes"]
 ....
 % svn propdel -R svn:mergeinfo {branchRelengx}
 % svn commit {branchRelengx}
 % svn commit {branchStablex}
 ....
 
 Now that two new `__FreeBSD_version` values exist, also update [.filename]#~/documentation/content/en/books/porters-handbook/versions/chapter.adoc# in the Documentation Project repository.
 
 After the first `RC` build has completed and tested, the {branchStable} branch can be "thawed" by removing (or commenting) the ^/{branchStablex} entry in [.filename]#svnadmin/conf/approvers#.
 
 Following the availability of the first `RC`, {teamBugmeister} should be emailed to add the new FreeBSD `-RELEASE` to the `versions` available in the drop-down menu shown in the bug tracker.
 
 [[releng-building]]
 == Building FreeBSD Installation Media
 
 This section describes the general procedures producing FreeBSD development snapshots and releases.
 
 [[releng-build-scripts]]
 === Release Build Scripts
 
 This section describes the build scripts used by {teamRe} to produce development snapshots and releases.
 
 [[releng-build-scripts-single]]
 ==== The [.filename]#release.sh# Script
 
 Prior to FreeBSD 9.0-RELEASE, [.filename]#src/release/Makefile# was updated to support , and the [.filename]#src/release/generate-release.sh# script was introduced as a wrapper to automate invoking the targets.
 
 Prior to FreeBSD 9.2-RELEASE, [.filename]#src/release/release.sh# was introduced, which heavily based on [.filename]#src/release/generate-release.sh# included support to specify configuration files to override various options and environment variables.
 Support for configuration files provided support for cross building each architecture for a release by specifying a separate configuration file for each invocation.
 
 As a brief example of using [.filename]#src/release/release.sh# to build a single release in [.filename]#/scratch#:
 
 [source,shell,subs="attributes"]
 ....
 # /bin/sh /usr/src/release/release.sh
 ....
 
 As a brief example of using [.filename]#src/release/release.sh# to build a single, cross-built release using a different target directory, create a custom [.filename]#release.conf# containing:
 
 [.programlisting,subs="attributes"]
 ....
 # release.sh configuration for powerpc/powerpc64
 CHROOTDIR="/scratch-powerpc64"
 TARGET="powerpc"
 TARGET_ARCH="powerpc64"
 KERNEL="GENERIC64"
 ....
 
 Then invoke [.filename]#src/release/release.sh# as:
 
 [source,shell,subs="attributes"]
 ....
 # /bin/sh /usr/src/release/release.sh -c $HOME/release.conf
 ....
 
 See and [.filename]#src/release/release.conf.sample# for more details and example usage.
 
 [[releng-build-scripts-multiple]]
 ==== The [.filename]#thermite.sh# Wrapper Script
 
 In order to make cross building the full set of architectures supported on a given branch faster, easier, and reduce human error factors, a wrapper script around [.filename]#src/release/release.sh# was written to iterate through the various combinations of architectures and invoke [.filename]#src/release/release.sh# using a configuration file specific to that architecture.
 
 The wrapper script is called [.filename]#thermite.sh#, which is available in the FreeBSD Subversion repository at `svn://svn.freebsd.org/base/user/gjb/thermite/`, in addition to configuration files used to build {branchHead} and {branchStablex} development snapshots.
 
 Using [.filename]#thermite.sh# is covered in <<releng-build-snapshot>> and <<releng-build-release>>.
 
 Each architecture and individual kernel have their own configuration file used by [.filename]#release.sh#.
 Each branch has its own [.filename]#defaults-X.conf# configuration which contains entries common throughout each architecture, where overrides or special variables are set and/or overridden in the per-build files.
 
 The per-build configuration file naming scheme is in the form of [.filename]#${revision}-${TARGET_ARCH}-${KERNCONF}-${type}.conf#, where the uppercase variables are equivalent to what uses in the build system, and lowercase variables are set within the configuration files, mapping to the major version of the respective branch.
 
 Each branch also has its own [.filename]#builds-X.conf# configuration, which is used by [.filename]#thermite.sh#. The [.filename]#thermite.sh# script iterates through each ${revision}, ${TARGET_ARCH}, ${KERNCONF}, and ${type} value, creating a master list of what to build.
 However, a given combination from the list will only be built if the respective configuration file exists, which is where the naming scheme above is relevant.
 
 There are two paths of file sourcing:
 
 * [.filename]#builds-12.conf# - [.filename]#main.conf#
-+ 
++
 This controls [.filename]#thermite.sh# behavior
 * [.filename]#12-amd64-GENERIC-snap.conf# - [.filename]#defaults-12.conf# - [.filename]#main.conf#
-+ 
++
 This controls [.filename]#release/release.sh# behavior within the build 
 
 [NOTE]
 ====
 The [.filename]#builds-12.conf#, [.filename]#defaults-12.conf#, and [.filename]#main.conf# configuration files exist to reduce repetition between the various per-build files.
 ====
 
 [[releng-build-snapshot]]
 === Building FreeBSD Development Snapshots
 
 The official release build machines have a specific filesystem layout, which using ZFS, [.filename]#thermite.sh# takes heavy advantage of with clones and snapshots, ensuring a pristine build environment.
 
 The build scripts reside in [.filename]#/releng/scripts-snapshot/scripts# or [.filename]#/releng/scripts-release/scripts# respectively, to avoid collisions between an `RC` build from a releng branch versus a `STABLE` snapshot from the respective stable branch.
 
 A separate dataset exists for the final build images, [.filename]#/snap/ftp#. This directory contains both snapshots and releases directories.
 They are only used if the `EVERYTHINGISFINE` variable is defined in [.filename]#main.conf#.
 
 [NOTE]
 ====
 The `EVERYTHINGISFINE` variable name was chosen to avoid colliding with a variable that might be possibly set in the user environment, accidentally enabling the behavior that depends on it being defined.
 ====
 
 As [.filename]#thermite.sh# iterates through the master list of combinations and locates the per-build configuration file, a ZFS dataset is created under [.filename]#/releng#, such as [.filename]#/releng/12-amd64-GENERIC-snap#.
 The `src/`, `ports/`, and `doc/` trees are checked out to separate ZFS datasets, such as [.filename]#/releng/12-src-snap#, which are then cloned and mounted into the respective build datasets.
 This is done to avoid checking out a given tree more than once.
 
 Assuming these filesystem paths, [.filename]#thermite.sh# would be invoked as:
 
 [source,shell,subs="attributes"]
 ....
 # cd /releng/scripts-snapshot/scripts
 # ./setrev.sh -b {branchStablex}
 # ./zfs-cleanup.sh -c ./builds-12.conf
 # ./thermite.sh -c ./builds-12.conf
 ....
 
 Once the builds have completed, additional helper scripts are available to generate development snapshot emails which are sent to the `freebsd-snapshots@freebsd.org` mailing list:
 
 [source,shell,subs="attributes"]
 ....
 # cd /releng/scripts-snapshot/scripts
 # ./get-checksums.sh -c ./builds-12.conf | ./generate-email.pl > snapshot-12-mail
 ....
 
 [NOTE]
 ====
 The generated output should be double-checked for correctness, and the email itself should be PGP signed, in-line.
 ====
 
 [NOTE]
 ====
 These helper scripts only apply to development snapshot builds.
 Announcements during the release cycle (excluding the final release announcement) are created from an email template.
 A sample of the email template currently used can be found link:here[here].
 ====
 
 [[releng-build-release]]
 === Building FreeBSD Releases
 
 Similar to building FreeBSD development snapshots, [.filename]#thermite.sh# would be invoked the same way.
 The difference between development snapshots and release builds, `BETA` and `RC` included, is that the configuration files must be named with `release` instead of `snap` as the type, as mentioned above.
 
 In addition, the `BUILDTYPE` and `types` must be changed from `snap` to `release` in [.filename]#defaults-12.conf# and [.filename]#builds-12.conf#, respectively.
 
 When building `BETA`, `RC`, and the final `RELEASE`, also statically set `BUILDSVNREV` to the revision on the branch reflecting the name change, `BUILDDATE` to the date the builds are started in `YYYYMMDD` format.
 If the `doc/` and `ports/` trees have been tagged, also set `PORTBRANCH` and `DOCBRANCH` to the relevant tag path in the Subversion repository, replacing `HEAD` with the last changed revision.
 Also set `releasesrc` in [.filename]#builds-12.conf# to the relevant branch, such as {branchStablex} or {branchRelengx}.
 
 During the release cycle, a copy of [.filename]#CHECKSUM.SHA512# and [.filename]#CHECKSUM.SHA256# for each architecture are stored in the {teamRe} internal repository in addition to being included in the various announcement emails.
 Each [.filename]#MANIFEST# containing the hashes of [.filename]#base.txz#, [.filename]#kernel.txz#, etc. are added to package:misc/freebsd-release-manifests[] in the Ports Collection, as well.
 
 In preparation for the release build, several files need to be updated:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File to Edit
 | What to Change
 
 |[.filename]#sys/conf/newvers.sh#
 |Update the `BRANCH` value to `RELEASE`
 
 |[.filename]#UPDATING#
 |Add the anticipated announcement date
 
 |[.filename]#lib/csu/common/crtbrand.c#
 |Replace `__FreeBSD_version` with the value in [.filename]#sys/sys/param.h#
 |===
 
 After building the final `RELEASE`, the {branchRelengx} branch is tagged as {branchReleasex} using the revision from which the `RELEASE` was built. 
 Similar to creating the {branchStablex} and {branchRelengx} branches, this is done with `svn cp`.
 From the repository root:
 
 [source,shell,subs="attributes"]
 ....
 % svn cp ^/{branchRelengx}@r306420 {branchReleasex}
 % svn commit {branchReleasex}
 ....
 
 [[releng-mirrors]]
 == Publishing FreeBSD Installation Media to Project Mirrors
 
 This section describes the procedure to publish FreeBSD development snapshots and releases to the Project mirrors.
 
 [[releng-mirrors-staging]]
 === Staging FreeBSD Installation Media Images
 
 Staging FreeBSD snapshots and releases is a two part process:
 
 * Creating the directory structure to match the hierarchy on `ftp-master`
-+ 
++
 If `EVERYTHINGISFINE` is defined in the build configuration files, [.filename]#main.conf# in the case of the build scripts referenced above, this happens automatically in the after the build is complete, creating the directory structure in [.filename]#${DESTDIR}/R/ftp-stage# with a path structure matching what is expected on `ftp-master`.
 This is equivalent to running the following in the directly:
 +
 [source,shell,subs="attributes"]
 ....
 # make -C /usr/src/release -f Makefile.mirrors EVERYTHINGISFINE=1 ftp-stage
 ....
-+ 
++
 After each architecture is built, [.filename]#thermite.sh# will rsync the [.filename]#${DESTDIR}/R/ftp-stage# from the build to [.filename]#/snap/ftp/snapshots# or [.filename]#/snap/ftp/releases# on the build host, respectively.
 * Copying the files to a staging directory on `ftp-master` before moving the files into [.filename]#pub/# to begin propagation to the Project mirrors
-+ 
++
 Once all builds have finished, [.filename]#/snap/ftp/snapshots#, or [.filename]#/snap/ftp/releases# for a release, is polled by `ftp-master` using rsync to [.filename]#/archive/tmp/snapshots# or [.filename]#/archive/tmp/releases#, respectively.
 +
 [NOTE]
 ====
 On `ftp-master` in the FreeBSD Project infrastructure, this step requires `root` level access, as this step must be executed as the `archive` user.
 ====
 
 [[releng-mirrors-publishing]]
 === Publishing FreeBSD Installation Media
 
 Once the images are staged in [.filename]#/archive/tmp/#, they are ready to be made public by putting them in [.filename]#/archive/pub/FreeBSD#.
 In order to reduce propagation time, is used to create hard links from [.filename]#/archive/tmp# to [.filename]#/archive/pub/FreeBSD#.
 
 [NOTE]
 ====
 In order for this to be effective, both [.filename]#/archive/tmp# and [.filename]#/archive/pub# must reside on the same logical filesystem.
 ====
 
 There is a caveat, however, where rsync must be used after in order to correct the symbolic links in [.filename]#pub/FreeBSD/snapshots/ISO-IMAGES# which will replace with a hard link, increasing the propagation time.
 
 [NOTE]
 ====
 As with the staging steps, this requires `root` level access, as this step must be executed as the `archive` user.
 ====
 
 As the `archive` user:
 
 [source,shell,subs="attributes"]
 ....
 % cd /archive/tmp/snapshots
 % pax -r -w -l . /archive/pub/FreeBSD/snapshots
 % /usr/local/bin/rsync -avH /archive/tmp/snapshots/* /archive/pub/FreeBSD/snapshots/
 ....
 
 Replace _snapshots_ with _releases_ as appropriate.
 
 [[releng-wrapup]]
 == Wrapping up the Release Cycle
 
 This section describes general post-release tasks.
 
 [[releng-wrapup-en]]
 === Post-Release Errata Notices
 
 As the release cycle approaches conclusion, it is common to have several EN (Errata Notice) candidates to address issues that were discovered late in the cycle.
 Following the release, the {teamRe} and the {teamSecteam} revisit changes that were not approved prior to the final release, and depending on the scope of the change in question, may issue an EN.
 
 [NOTE]
 ====
 The actual process of issuing ENs is handled by the {teamSecteam}.
 ====
 
 To request an Errata Notice after a release cycle has completed, a developer should fill out the https://www.freebsd.org/security/errata-template.txt[Errata Notice template], in particular the `Background`, `Problem Description`, `Impact`, and if applicable, `Workaround` sections.
 
 The completed Errata Notice template should be emailed together with either a patch against the {branchReleng} branch or a list of revisions from the {branchStable} branch.
 
 For Errata Notice requests immediately following the release, the request should be emailed to both the {teamRe} and the {teamSecteam}.
 Once the {branchReleng} branch has been handed over to the {teamSecteam} as described in <<releng-wrapup-handoff>>, Errata Notice requests should be sent to the {teamSecteam}.
 
 [[releng-wrapup-handoff]]
 === Handoff to the {teamSecteam}
 
 Roughly two weeks following the release, the Release Engineer updates [.filename]#svnadmin/conf/approvers# changing the approver column from `re` to `(so|security-officer)` for the {branchRelengx} branch.
 
 [[releng-eol]]
 == Release End-of-Life
 
 This section describes the website-related files to update when a release reaches EoL (End-of-Life).
 
 [[releng-eol-website]]
 === Website Updates for End-of-Life
 
 When a release reaches End-of-Life, references to that release should be removed and/or updated on the website:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File
 | What to Change
 
 
 |[.filename]#~/website/themes/beastie/layouts/index.html#
 |Remove `u-relXXX-announce` and `u-relXXX-announce` references.
 
 |[.filename]#~/website/content/en/releases/_index.adoc#
 |Move the `u-relXXX-*` variables from the supported release list to the Legacy Releases list.
 
 |[.filename]#~/website/content/en/releng/_index.adoc#
 |Update the appropriate releng branch to refelect the branch is no longer supported.
 
 |[.filename]#~/website/content/en/security/_index.adoc#
 |Remove the branch from the supported branch list.
 
 |[.filename]#~/website/content/en/where.adoc#
 |Remove the URLs for the release.
 
 |[.filename]#~/website/themes/beastie/layouts/partials/sidenav.html#
 |Remove `u-relXXX-announce` and `u-relXXX-announce` references.
 
 |[.filename]#~/website/static/security/advisory-template.txt#
 |Remove references to the release and releng branch.
 
 |[.filename]#~/website/static/security/errata-template.txt#
 |Remove references to the release and releng branch.
 |===
diff --git a/documentation/content/en/articles/mailing-list-faq/_index.adoc b/documentation/content/en/articles/mailing-list-faq/_index.adoc
index 5f3322f29f..d70b735075 100644
--- a/documentation/content/en/articles/mailing-list-faq/_index.adoc
+++ b/documentation/content/en/articles/mailing-list-faq/_index.adoc
@@ -1,206 +1,206 @@
 ---
 title: Frequently Asked Questions About The FreeBSD Mailing Lists
 authors:
   - author: The FreeBSD Documentation Project
 copyright: 2004-2021 The FreeBSD Documentation Project
 description: How to best use the mailing lists, such as how to help avoid frequently-repeated discussions
 tags: ["FAQ", "Mailing Lists", "FreeBSD"]
 ---
 
 = Frequently Asked Questions About The FreeBSD Mailing Lists
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 ifeval::["{backend}" == "html5"]
 include::shared/authors.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/urls.adoc[]
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 include::../../../../shared/authors.adoc[]
 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 include::../../../../shared/authors.adoc[]
 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
 [.abstract-title]
 Abstract
 
 This is the FAQ for the FreeBSD mailing lists.
 If you are interested in helping with this project, send email to the {freebsd-doc}.
 The latest version of this document is always available from the link:.[FreeBSD World Wide Web server].
 It may also be downloaded as one large link:.[HTML] file with HTTP or as plain text, PostScript, PDF, etc. from the https://download.freebsd.org/ftp/doc/[FreeBSD FTP server].
 You may also want to link:https://www.FreeBSD.org/search/[Search the FAQ].
 
 '''
 
 toc::[]
 
 [[introduction]]
 == Introduction
 
 As is usual with FAQs, this document aims to cover the most frequently asked questions concerning the FreeBSD mailing lists (and of course answer them!). 
 Although originally intended to reduce bandwidth and avoid the same old questions being asked over and over again, FAQs have become recognized as valuable information resources.
 
 This document attempts to represent a community consensus, and as such it can never really be __authoritative__.
 However, if you find technical errors within this document, or have suggestions about items that should be added, please either submit a PR, or email the {freebsd-doc}.
 Thanks.
 
 === What is the purpose of the FreeBSD mailing lists?
 
 The FreeBSD mailing lists serve as the primary communication channels for the FreeBSD community, covering many different topic areas and communities of interest.
 
 === Who is the audience for the FreeBSD mailing lists?
 
 This depends on charter of each individual list.
 Some lists are more oriented to developers; some are more oriented towards the FreeBSD community as a whole.
 Please see http://lists.FreeBSD.org/mailman/listinfo[this list] for the current summary.
 
 === Are the FreeBSD mailing lists open for anyone to participate?
 
 Again, this depends on charter of each individual list.
 Please read the charter of a mailing list before you post to it, and respect it when you post.
 This will help everyone to have a better experience with the lists.
 
 If after reading the above lists, you still do not know which mailing list to post a question to, you will probably want to post to freebsd-questions (but see below, first).
 
 Also note that the mailing lists have traditionally been open to postings from non-subscribers.
 This has been a deliberate choice, to help make joining the FreeBSD community an easier process, and to encourage open sharing of ideas.
 However, due to past abuse by some individuals, certain lists now have a policy where postings from non-subscribers must be manually screened to ensure that they are appropriate.
 
 === How can I subscribe?
 
 You can use http://lists.FreeBSD.org/mailman/listinfo[the Mailman web interface] to subscribe to any of the public lists.
 
 === How can I unsubscribe?
 
 You can use the same interface as above; or, you can follow the instructions that are at the bottom of every mailing list message that is sent.
 
 Please do not send unsubscribe messages directly to the public lists themselves.
 First, this will not accomplish your goal, and second, it will irritate the existing subscribers, and you will probably get flamed.
 This is a classical mistake when using mailing lists; please try to avoid it.
 
 === Are archives available?
 
 Yes. Threaded archives are available http://docs.FreeBSD.org/mail/[here].
 
 === Are mailing lists available in a digest format?
 
 Yes. See http://lists.FreeBSD.org/mailman/listinfo[the Mailman web interface].
 
 [[etiquette]]
 == Mailing List Etiquette
 
 Participation in the mailing lists, like participation in any community, requires a common basis for communication.
 Please make only appropriate postings, and follow common rules of etiquette.
 
 === What should I do before I post?
 
 You have already taken the most important step by reading this document.
 However, if you are new to FreeBSD, you may first need to familiarize yourself with the software, and all the social history around it, by reading the numerous link:https://www.FreeBSD.org/docs/books/[books and articles] that are available.
 Items of particular interest include the link:{faq}[FreeBSD Frequently Asked Questions (FAQ)] document, the link:{handbook}[FreeBSD Handbook], and the articles link:{freebsd-questions-article}[How to get best results from the FreeBSD-questions mailing list], link:{explaining-bsd}[Explaining BSD], and link:{new-users}[FreeBSD First Steps].
 
 It is always considered bad form to ask a question that is already answered in the above documents.
 This is not because the volunteers who work on this project are particularly mean people, but after a certain number of times answering the same questions over and over again, frustration begins to set in.
 This is particularly true if there is an existing answer to the question that is already available.
 Always keep in mind that almost all of the work done on FreeBSD is done by volunteers, and that we are only human.
 
 === What constitutes an inappropriate posting?
 
 * Postings must be in accordance with the charter of the mailing list.
 * Personal attacks are discouraged. As good net-citizens, we should try to hold ourselves to high standards of behavior.
 * Spam is not allowed, ever. The mailing lists are actively processed to ban offenders to this rule.
 
 === What is considered proper etiquette when posting to the mailing lists?
 
 * Please wrap lines at 75 characters, since not everyone uses fancy GUI mail reading programs.
 * Please respect the fact that bandwidth is not infinite. Not everyone reads email through high-speed connections, so if your posting involves something like the content of [.filename]#config.log# or an extensive stack trace, please consider putting that information up on a website somewhere and just provide a URL to it. Remember, too, that these postings will be archived indefinitely, so huge postings will simply inflate the size of the archives long after their purpose has expired.
 * Format your message so that it is legible, and PLEASE DO NOT SHOUT!!!!!. Do not underestimate the effect that a poorly formatted mail message has, and not just on the FreeBSD mailing lists. Your mail message is all that people see of you, and if it is poorly formatted, badly spelled, full of errors, and/or has lots of exclamation points, it will give people a poor impression of you.
 * Please use an appropriate human language for a particular mailing list. Many non-English mailing lists are link:https://www.FreeBSD.org/community/mailinglists/[available].
-+ 
++
 For the ones that are not, we do appreciate that many people do not speak English as their first language, and we try to make allowances for that.
 It is considered particularly poor form to criticize non-native speakers for spelling or grammatical errors.
 FreeBSD has an excellent track record in this regard; please, help us to uphold that tradition.
 * Please use a standards-compliant Mail User Agent (MUA). A lot of badly formatted messages come from http://www.lemis.com/grog/email/email.php[bad mailers or badly configured mailers]. The following mailers are known to send out badly formatted messages without you finding out about them:
 
 ** exmh
 ** Microsoft(R) Exchange
 ** Microsoft(R) Outlook(R)
-+ 
++
 Try not to use MIME: a lot of people use mailers which do not get on very well with MIME.
 * Make sure your time and time zone are set correctly. This may seem a little silly, since your message still gets there, but many of the people on these mailing lists get several hundred messages a day. They frequently sort the incoming messages by subject and by date, and if your message does not come before the first answer, they may assume that they missed it and not bother to look.
 * A lot of the information you need to supply is the output of programs, such as man:dmesg[8], or console messages, which usually appear in [.filename]#/var/log/messages#. Do not try to copy this information by typing it in again; not only it is a real pain, but you are bound to make a mistake. To send log file contents, either make a copy of the file and use an editor to trim the information to what is relevant, or cut and paste into your message. For the output of programs like `dmesg`, redirect the output to a file and include that. For example,
 +
 [source,shell]
 ....
 % dmesg > /tmp/dmesg.out
 ....
-+ 
++
 This redirects the information to the file [.filename]#/tmp/dmesg.out#.
 * When using cut-and-paste, please be aware that some such operations badly mangle their messages. This is of particular concern when posting contents of [.filename]#Makefiles#, where `tab` is a significant character. This is a very common, and very annoying, problem with submissions to the link:https://www.FreeBSD.org/support/[Problem Reports database]. [.filename]#Makefiles# with tabs changed to either spaces, or the annoying `=3B` escape sequence, create a great deal of aggravation for committers.
 
 === What are the special etiquette consideration when replying to an existing posting on the mailing lists?
 
 * Please include relevant text from the original message. Trim it to the minimum, but do not overdo it. It should still be possible for somebody who did not read the original message to understand what you are talking about.
-+ 
++
 This is especially important for postings of the type "yes, I see this too", where the initial posting was dozens or hundreds of lines.
 * Use some technique to identify which text came from the original message, and which text you add. A common convention is to prepend "`>`" to the original message. Leaving white space after the "`>`" and leaving empty lines between your text and the original text both make the result more readable.
 * Please ensure that the attributions of the text you are quoting is correct. People can become offended if you attribute words to them that they themselves did not write.
 * Please do not `top post`. By this, we mean that if you are replying to a message, please put your replies after the text that you copy in your reply.
 +
 ** A: Because it reverses the logical flow of conversation.
 ** Q: Why is top posting frowned upon?
-+ 
++
 (Thanks to Randy Bush for the joke.)
 
 [[recurring]]
 == Recurring Topics On The Mailing Lists
 
 Participation in the mailing lists, like participation in any community, requires a common basis for communication.
 Many of the mailing lists presuppose a knowledge of the Project's history.
 In particular, there are certain topics that seem to regularly occur to newcomers to the community.
 It is the responsibility of each poster to ensure that their postings do not fall into one of these categories.
 By doing so, you will help the mailing lists to stay on-topic, and probably save yourself being flamed in the process.
 
 The best method to avoid this is to familiarize yourself with the http://docs.FreeBSD.org/mail/[mailing list archives], to help yourself understand the background of what has gone before.
 In this, the https://www.FreeBSD.org/search/#mailinglists[mailing list search interface] is invaluable.
 (If that method does not yield useful results, please supplement it with a search with your favorite major search engine).
 
 By familiarizing yourself with the archives, not only will you learn what topics have been discussed before, but also how discussion tends to proceed on that list, who the participants are, and who the target audience is.
 These are always good things to know before you post to any mailing list, not just a FreeBSD mailing list.
 
 There is no doubt that the archives are quite extensive, and some questions recur more often than others, sometimes as followups where the subject line no longer accurately reflects the new content.
 Nevertheless, the burden is on you, the poster, to do your homework to help avoid these recurring topics.
 
 [[bikeshed]]
 == What Is A "Bikeshed"?
 
 Literally, a `bikeshed` is a small outdoor shelter into which one may store one's two-wheeled form of transportation.
 However, in FreeBSD parlance, the term refers to topics that are simple enough that (nearly) anyone can offer an opinion about, and often (nearly) everyone does. The genesis of this term is explained in more detail link:{faq}#bikeshed-painting[in this document].
 You simply must have a working knowledge of this concept before posting to any FreeBSD mailing list.
 
 More generally, a bikeshed is a topic that will tend to generate immediate meta-discussions and flames if you have not read up on their past history.
 
 Please help us to keep the mailing lists as useful for as many people as possible by avoiding bikesheds whenever you can.
 Thanks.
 
 [[acknowledgments]]
 == Acknowledgments
 
 `{grog}`::
 Original author of most of the material on mailing list etiquette, taken from the article on link:{freebsd-questions-article}[How to get best results from the FreeBSD-questions mailing list].
 
 `{linimon}`::
 Creation of the rough draft of this FAQ.
diff --git a/documentation/content/en/articles/nanobsd/_index.adoc b/documentation/content/en/articles/nanobsd/_index.adoc
index b819e0ee10..b90ac20046 100644
--- a/documentation/content/en/articles/nanobsd/_index.adoc
+++ b/documentation/content/en/articles/nanobsd/_index.adoc
@@ -1,446 +1,446 @@
 ---
 title: Introduction to NanoBSD
 authors:
   - author: Daniel Gerzo
 copyright: 2006 The FreeBSD Documentation Project
 description: This document provides information about the NanoBSD tools, which can be used to create FreeBSD system images for embedded applications, suitable for use on a USB key, memory card or other mass storage media.
 trademarks: ["freebsd", "general"]
 tags: ["nanobsd", "guide", "embedded", "FreeBSD"]
 ---
 
 = Introduction to NanoBSD
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 ifeval::["{backend}" == "html5"]
 include::shared/authors.adoc[]
 include::shared/en/urls.adoc[]
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 include::../../../../shared/authors.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 include::../../../../shared/authors.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
 [.abstract-title]
 Abstract
 
 This document provides information about the NanoBSD tools, which can be used to create FreeBSD system images for embedded applications, suitable for use on a USB key, memory card or other mass storage media.
 
 '''
 
 toc::[]
 
 [[intro]]
 == Introduction to NanoBSD
 
 NanoBSD is a tool developed by {phk} and now maintained by {imp}.
 It creates a FreeBSD system image for embedded applications, suitable for use on a USB key, memory card or other mass storage media.
 
 It can be used to build specialized install images, designed for easy installation and maintenance of systems commonly called "computer appliances". 
 Computer appliances have their hardware and software bundled in the product, which means all applications are pre-installed.
 The appliance is plugged into an existing network and can begin working (almost) immediately.
 
 The features of NanoBSD include:
 
 * Ports and packages work as in FreeBSD - Every single application can be installed and used in a NanoBSD image, the same way as in FreeBSD.
 * No missing functionality - If it is possible to do something with FreeBSD, it is possible to do the same thing with NanoBSD, unless the specific feature or features were explicitly removed from the NanoBSD image when it was created.
 * Everything is read-only at run-time - It is safe to pull the power-plug. There is no necessity to run man:fsck[8] after a non-graceful shutdown of the system.
 * Easy to build and customize - Making use of just one shell script and one configuration file it is possible to build reduced and customized images satisfying any arbitrary set of requirements.
 
 [[howto]]
 == NanoBSD Howto
 
 [[design]]
 === The Design of NanoBSD
 
 Once the image is present on the medium, it is possible to boot NanoBSD.
 The mass storage medium is divided into three parts by default:
 
 * Two image partitions: `code#1` and `code#2`.
 * The configuration file partition, which can be mounted under the [.filename]#/cfg# directory at run time.
 
 These partitions are normally mounted read-only.
 
 The [.filename]#/etc# and [.filename]#/var# directories are man:md[4] (malloc) disks.
 
 The configuration file partition persists under the [.filename]#/cfg# directory.
 It contains files for [.filename]#/etc# directory and is briefly mounted read-only right after the system boot, therefore it is required to copy modified files from [.filename]#/etc# back to the [.filename]#/cfg# directory if changes are expected to persist after the system restarts.
 
 .Making Persistent Changes to [.filename]#/etc/resolv.conf#
 [example]
 ====
 
 [source,shell]
 ....
 # vi /etc/resolv.conf
 [...]
 # mount /cfg
 # cp /etc/resolv.conf /cfg
 # umount /cfg
 ....
 
 ====
 
 [NOTE]
 ====
 The partition containing [.filename]#/cfg# should be mounted only at boot time and while overriding the configuration files.
 
 Keeping [.filename]#/cfg# mounted at all times is not a good idea, especially if the NanoBSD system runs off a mass storage medium that may be adversely affected by a large number of writes to the partition (like when the filesystem syncer flushes data to the system disks).
 ====
 
 === Building a NanoBSD Image
 
 A NanoBSD image is built using a simple [.filename]#nanobsd.sh# shell script, which can be found in the [.filename]#/usr/src/tools/tools/nanobsd# directory.
 This script creates an image, which can be copied on the storage medium using the man:dd[1] utility.
 
 The necessary commands to build a NanoBSD image are:
 
 [source,shell]
 ....
 # cd /usr/src/tools/tools/nanobsd <.>
 # sh nanobsd.sh <.>
 # cd /usr/obj/nanobsd.full <.>
 # dd if=_.disk.full of=/dev/da0 bs=64k <.>
 ....
 
 <.> Change the current directory to the base directory of the NanoBSD build script.
 
 <.> Start the build process.
 
 <.> Change the current directory to the place where the built images are located.
 
 <.> Install NanoBSD onto the storage medium.
 
 ==== Options When Building a NanoBSD Image
 
 When building a NanoBSD image, several build options can be passed to [.filename]#nanobsd.sh# on the command line.
 These options can have a significant impact on the build process.
 
 Some options are for verbosity purposes:
 
 * `-h`: prints the help summary page.
 * `-q`: makes output quieter.
 * `-v`: makes output more verbose
 
 Some other options can be used to restrict the building process.
 Sometimes it is not necessary to rebuild everything from sources, especially if an image has already been built, and only little change is made.
 
 * `-k`: do not build the kernel
 * `-w`: do not build world
 * `-b`: do not build either kernel and world
 * `-i`: do not build a disk image at all. As a file will not be created, it will not be possible to man:dd[1] it to a storage media.
 * `-f`: do not build a disk image of the first partition (which is useful for upgrade purposes)
 * `-n`: add `-DNO_CLEAN` to `buildworld`, `buildkernel`. Also, all the files that have already been built in a previous run are kept.
 
 A configuration file can be used to tweak as many elements as desired.
 Load it with `-c`
 
 The last options are:
 
 * `-K`: do not install a kernel. A disk image without a kernel will not be able to achieve a normal boot sequence. 
 
 ==== The Complete Image Building Process
 
 The complete image building process is going through a lot of steps.
 The exact steps taken will depend on the chosen options when starting the script.
 Assuming the script is run with no particular options, this is what will happen.
 
 . `run_early_customize`: commands that are defined in a supplied configuration file.
 . `clean_build`: Just cleans the build environment by deleting the previously built files.
 . `make_conf_build`: Assemble make.conffrom the `CONF_WORLD` and `CONF_BUILD` variables.
 . `build_world`: Build world.
 . `build_kernel`: Build the kernel files.
 . `clean_world`: Clean the destination directory.
 . `make_conf_install`: Assemble make.conf from the `CONF_WORLD` and `CONF_INSTALL` variables.
 . `install_world`: Install all files built during `buildworld`.
 . `install_etc`: Install the necessary files in the [.filename]#/etc# directory, based on the `make distribution` command.
 . `setup_nanobsd_etc`: the first configuration specific to NanoBSD takes place at this stage. The [.filename]#/etc/diskless# is created and the root filesystem is defined as read-only.
 . `install_kernel`: the kernel and modules files are installed.
 . `run_customize`: all the customizing routines defined by the user will be called.
 . `setup_nanobsd`: a special configuration directory layout is setup. The [.filename]#/usr/local/etc# gets moved to [.filename]#/etc/local# and a symbolic link is created back from [.filename]#/etc/local# to [.filename]#/usr/local/etc#.
 . `prune_usr`: the empty directories from [.filename]#/usr# are removed.
 . `run_late_customize`: the very last custom scripts can be run at this point.
 . `fixup_before_diskimage`: List all installed files in a metalog
 . `create_diskimage`: creates the actual disk image, based on the disk geometries provides parameters.
 . `last_orders`: does nothing for now.
 
 === Customizing a NanoBSD Image
 
 This is probably the most important and most interesting feature of NanoBSD.
 This is also where you will be spending most of the time when developing with NanoBSD.
 
 Invocation of the following command will force the [.filename]#nanobsd.sh# to read its configuration from [.filename]#myconf.nano# located in the current directory:
 
 [source,shell]
 ....
 # sh nanobsd.sh -c myconf.nano
 ....
 
 Customization is done in two ways:
 
 * Configuration options
 * Custom functions
 
 ==== Configuration Options
 
 With configuration settings, it is possible to configure options passed to both the `buildworld` and `installworld` stages of the NanoBSD build process, as well as internal options passed to the main build process of NanoBSD.
 Through these options it is possible to cut the system down, so it will fit on as little as 64MB.
 You can use the configuration options to trim down FreeBSD even more, until it will consists of just the kernel and two or three files in the userland.
 
 The configuration file consists of configuration options, which override the default values.
 The most important directives are:
 
 * `NANO_NAME` - Name of build (used to construct the workdir names).
 * `NANO_SRC` - Path to the source tree used to build the image.
 * `NANO_KERNEL` - Name of kernel configuration file used to build kernel.
 * `CONF_BUILD` - Options passed to the `buildworld` stage of the build.
 * `CONF_INSTALL` - Options passed to the `installworld` stage of the build.
 * `CONF_WORLD` - Options passed to both the `buildworld` and the `installworld` stage of the build.
 * `FlashDevice` - Defines what type of media to use. Check [.filename]#FlashDevice.sub# for more details.
 
 There are many more configuration options that could be relevant depending upon the kind of NanoBSD that is desired.
 
 ===== General Customization
 
 There are three stages, by design, at which it is possible to make changes that affect the building process, just by setting up a variable in the provided configuration file:
 
 * `run_early_customize`: before anything else happens.
 * `run_customize`: after all the standard files have been laid out
 * `run_late_customize`: at the very end of the process, just before the actual NanoBSD image is built.
 
 To customize a NanoBSD image, at any of these steps, it is best to add a specific value to one of the corresponding variables.
 
 The `NANO_EARLY_CUSTOMIZE` variable is used at the first step of the building process.
 At this point, there is no example as to what can be done using that variable, but it may change in the future.
 
 The `NANO_CUSTOMIZE` variable is used after the kernel, world and etc configuration files have been installed, and the etc files have been setup as to be a NanoBSD installation.
 So it is the correct step in the building process to tweak configuration options and add packages, like in the cust_nobeastie example.
 
 The `NANO_LATE_CUSTOMIZE` variable is used just before the disk image is created, so it is the very last moment to change anything.
 Remember that the `setup_nanobsd` routine already executed and that the [.filename]#etc#, [.filename]#conf# and [.filename]#cfg# directories and subdirectories are already modified, so it is not time to change them at this point.
 Rather, it is possible to add or remove specific files.
 
 ===== Booting Options
 
 There are also variables that can change the way the NanoBSD image boots.
 Two options are passed to man:boot0cfg[8] to initialize the boot sector of the disk image:
 
 * `NANO_BOOT0CFG`
 * `NANO_BOOTLOADER`
 
 With `NANO_BOOTLOADER` a bootloader file can be chosen.
 The most common possible options are between [.filename]#boot0sio# and [.filename]#boot0# depending on whether the appliance has a serial port or not.
 It is best to avoid supplying a different bootloader, but it is possible.
 To do so, it is best to have checked the link:{handbook}boot/[FreeBSD Handbook] chapter on the boot process.
 
 With `NANO_BOOT0CFG`, the booting process can be tweaked, like selecting on which partition the NanoBSD image will actually boot.
 It is best to check the man:boot0cfg[8] page before changing the default value of this variable.
 One option that could be interesting to change is the timeout of the booting procedure.
 To do so, the `NANO_BOOT0CFG` variable can be changed to `"-o packet -s 1 -m 3 -t 36"`.
 That way the booting process would start after approximately 2 seconds;
 because it is rare that waiting 10 seconds before actually booting is desired.
 
 Good to know: the `NANO_BOOT2CFG` variable is only used in the `cust_comconsole` routine that can be called at the `NANO_CUSTOMIZE` step if the appliance has a serial port and all console input and output has to take place through it.
 Be sure to check the relevant parameters of the serial port, as setting a bad parameter value can make it useless.
 
 ===== Disk Image Creation
 
 In the end of the boot process is the disk image creation.
 With this step, the NanoBSD script provides a file that can simply be copied onto a disk for the appliance, and that will make it boot and start.
 
 There are many variable that need to be set just right for the script to produce a usable disk image.
 
 * The `NANO_DRIVE` variable must be set to the drive name of the media at runtime. Usually, the default value `ada0`, which represents the first `IDE`/`ATA`/`SATA` device on the appliance is expected to be the correct one, but a different type of storage could also be used - like a USB key, in which case, it would rather be da0.
 * The `NANO_MEDIASIZE` variable must be set to the size (in 512 bytes sectors) of the storage media that will be used. If you set it wrong, it is possible that the NanoBSD image will not boot at all, and a message at boot time will be warning about incorrect disk geometry.
 
 * The [.filename]#/etc#, [.filename]#/var#, and [.filename]#/tmp# directories are allocated as man:md[4] (malloc) disks at boot time; so their sizes can be tailored to suit the appliance needs. The `NANO_RAM_ETCSIZE` variable sets the size of the [.filename]#/etc#; and the `NANO_RAM_TMPVARSIZE` variable sets the size of both the [.filename]#/var# and [.filename]#/tmp# directory, as [.filename]#/tmp# is symbolically linked to [.filename]#/var/tmp#. By default, both malloc disks sizes are set at 20MB each. They can always be changed, but usually the [.filename]#/etc# does not grow too much in size, so 20MB is a good starting point, whereas the [.filename]#/var# and especially [.filename]#/tmp# can grow much larger if not careful about it. For memory constrained systems, smaller filesystem sizes may be chosen. 
 * As NanoBSD is mainly designed to build a system image for an appliance, it is assumed that the storage media used will be relatively small. For that reason, the filesystem that is laid out is configured to have a small block size (4Kb) and a small fragment size (512b). The configuration options of the filesystem can be modified through the `NANO_NEWFS` variable, but the syntax must respect the man:newfs[8] command format. Also, by default, the filesystem has Soft Updates enabled. The link:{handbook}[FreeBSD Handbook] can be checked about this.
 * The different partition sizes can be set through the use of `NANO_CODESIZE`, `NANO_CONFSIZE`, and `NANO_DATASIZE` as a multiple of 512 bytes sectors. `NANO_CODESIZE` defines the size of the first two image partitions: `code#1` and `code#2`. They have to be big enough to hold all the files that will be produced as a result of the `buildworld` and `buildkernel` processes. `NANO_CONFSIZE` defines the size of the configuration file partition, so it does not need to be very big; but do not make it so small that it will not hold all configuration files. Finally, `NANO_DATASIZE` defines the size of an optional partition, that can be used on the appliance. The last partition can be used, for example, to keep files created on the fly on disk.
 
 ==== Custom Functions
 
 It is possible to fine-tune NanoBSD using shell functions in the configuration file.
 The following example illustrates the basic model of custom functions:
 
 [.programlisting]
 ....
 cust_foo () (
 	echo "bar=baz" > \
 		${NANO_WORLDDIR}/etc/foo
 )
 customize_cmd cust_foo
 ....
 
 A more useful example of a customization function is the following, which changes the default size of the [.filename]#/etc# directory from 5MB to 30MB:
 
 [.programlisting]
 ....
 cust_etc_size () (
 	cd ${NANO_WORLDDIR}/conf
 	echo 30000 > default/etc/md_size
 )
 customize_cmd cust_etc_size
 ....
 
 There are a few default pre-defined customization functions ready for use:
 
 * `cust_comconsole` - Disables man:getty[8] on the VGA devices (the [.filename]#/dev/ttyv*# device nodes) and enables the use of the COM1 serial port as the system console.
 * `cust_allow_ssh_root` - Allow `root` to login via man:sshd[8].
 * `cust_install_files` - Installs files from the [.filename]#nanobsd/Files# directory, which contains some useful scripts for system administration.
 
 ==== Adding Packages
 
 Packages can be added to a NanoBSD image, to provide specific functionalities on the appliance. To do so, either:
 
 * Add the `cust_pkgng` to the `NANO_CUSTOMIZE` variable, or
 * Add a `'customize_cmd cust_pkgng'` command in a customized configuration file.
 
 Both methods achieve the same result: launching the `cust_pkgng` routine.
 This routine will go through `NANO_PACKAGE_DIR` directory to find either all packages or just the list of packages in the `NANO_PACKAGE_LIST` variable.
 
 It is common, when installing applications through pkg on a standard FreeBSD environment, that the install process puts configuration files, in the [.filename]#usr/local/etc# directory, and startup scripts in the [.filename]#/usr/local/etc/rc.d# directory.
 So, after the required packages have been installed, they need to be configured in order for them to start right out of the box.
 To do so, the necessary configuration files have to be installed in the correct directories.
 This can be achieved by writing dedicated routines or the generic `cust_install_files` routine can be used to lay out files properly from the [.filename]#/usr/src/tools/tools/nanobsd/Files# directory.
 Usually a statement, sometimes multiple statements, in the [.filename]#/etc/rc.conf# also needs to be added for each package.
 
 ==== Configuration File Example
 
 A complete example of a configuration file for building a custom NanoBSD image can be:
 
 [.programlisting]
 ....
 NANO_NAME=custom
 NANO_SRC=/usr/src
 NANO_KERNEL=MYKERNEL
 NANO_IMAGES=2
 
 CONF_BUILD='
 WITHOUT_KLDLOAD=YES
 WITHOUT_NETGRAPH=YES
 WITHOUT_PAM=YES
 '
 
 CONF_INSTALL='
 WITHOUT_ACPI=YES
 WITHOUT_BLUETOOTH=YES
 WITHOUT_FORTRAN=YES
 WITHOUT_HTML=YES
 WITHOUT_LPR=YES
 WITHOUT_MAN=YES
 WITHOUT_SENDMAIL=YES
 WITHOUT_SHAREDOCS=YES
 WITHOUT_EXAMPLES=YES
 WITHOUT_INSTALLLIB=YES
 WITHOUT_CALENDAR=YES
 WITHOUT_MISC=YES
 WITHOUT_SHARE=YES
 '
 
 CONF_WORLD='
 WITHOUT_BIND=YES
 WITHOUT_MODULES=YES
 WITHOUT_KERBEROS=YES
 WITHOUT_GAMES=YES
 WITHOUT_RESCUE=YES
 WITHOUT_LOCALES=YES
 WITHOUT_SYSCONS=YES
 WITHOUT_INFO=YES
 '
 
 FlashDevice SanDisk 1G
 
 cust_nobeastie() (
 	touch ${NANO_WORLDDIR}/boot/loader.conf
 	echo "beastie_disable=\"YES\"" >> ${NANO_WORLDDIR}/boot/loader.conf
 )
 
 customize_cmd cust_comconsole
 customize_cmd cust_install_files
 customize_cmd cust_allow_ssh_root
 customize_cmd cust_nobeastie
 ....
 
 All the build and install compilation options can be found in the man:src.conf[5] man page, but not all options can or should be used when building a NanoBSD image.
 The build and install options should be defined according to the needs of the image being built.
 
 For example, the ftp client and server might not be needed.
 Adding `WITHOUT_FTP=TRUE` to a configuration file in the `CONF_BUILD` section will avoid having them built.
 Also, if the NanoBSD appliance will not be used to build programs then it is possible to add the `WITHOUT_BINUTILS=TRUE` in the `CONF_INSTALL` section; but not in the `CONF_BUILD` section as they will be used to build the NanoBSD image.
 
 Not building a particular set of programs - through a compilation option - shortens the overall building time and lowers the required size for the disk image, whereas not installing the same specific set of programs does not lower the overall building time.
 
 === Updating NanoBSD
 
 The update process of NanoBSD is relatively simple:
 
 [.procedure]
 ====
 . Build a new NanoBSD image, as usual.
 . Upload the new image into an unused partition of a running NanoBSD appliance.
-+ 
++
 The most important difference of this step from the initial NanoBSD installation is that now instead of using [.filename]#\_.disk.full# (which contains an image of the entire disk), the [.filename]#_.disk.image# image is installed (which contains an image of a single system partition).
 . Reboot, and start the system from the newly installed partition.
 . If all goes well, the upgrade is finished.
 . If anything goes wrong, reboot back into the previous partition (which contains the old, working image), to restore system functionality as fast as possible. Fix any problems of the new build, and repeat the process.
 ====
 
 To install new image onto the running NanoBSD system, it is possible to use either the [.filename]#updatep1# or [.filename]#updatep2# script located in the [.filename]#/root# directory, depending from which partition is running the current system.
 
 According to which services are available on host serving new NanoBSD image and what type of transfer is preferred, it is possible to examine one of these three ways:
 
 ==== Using man:ftp[1]
 
 If the transfer speed is in first place, use this example:
 
 [source,shell]
 ....
 # ftp myhost
 get _.disk.image "| sh updatep1"
 ....
 
 ==== Using man:ssh[1]
 
 If a secure transfer is preferred, consider using this example:
 
 [source,shell]
 ....
 # ssh myhost cat _.disk.image.gz | zcat | sh updatep1
 ....
 
 ==== Using man:nc[1]
 
 Try this example if the remote host is not running neither man:ftpd[8] or man:sshd[8] service:
 
 [.procedure]
 ====
 . At first, open a TCP listener on host serving the image and make it send the image to client:
 +
 [source,shell]
 ....
 myhost# nc -l 2222 < _.disk.image
 ....
 +
 [NOTE]
 ======
 Make sure that the used port is not blocked to receive incoming connections from NanoBSD host by firewall.
 ======
 . Connect to the host serving new image and execute [.filename]#updatep1# script:
 +
 [source,shell]
 ....
 # nc myhost 2222 | sh updatep1
 ....
 ====
diff --git a/documentation/content/en/articles/problem-reports/_index.adoc b/documentation/content/en/articles/problem-reports/_index.adoc
index d92d95945e..42ada1e99a 100644
--- a/documentation/content/en/articles/problem-reports/_index.adoc
+++ b/documentation/content/en/articles/problem-reports/_index.adoc
@@ -1,284 +1,284 @@
 ---
 title: Writing FreeBSD Problem Reports
 authors:
   - author: Dag-Erling Smørgrav
   - author: Mark Linimon
 description: How to best formulate and submit a problem report to the FreeBSD Project
 trademarks: ["freebsd", "ibm", "intel", "sun", "general"]
 tags: ["formulate", "submit", "FreeBSD", "PR"]
 ---
 
 = Writing FreeBSD Problem Reports
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 ifeval::["{backend}" == "html5"]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/urls.adoc[]
 endif::[]
 
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 include::../../../../shared/en/mailing-lists.adoc[]
 include::../../../../shared/en/urls.adoc[]
 endif::[]
 
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 include::../../../../shared/en/mailing-lists.adoc[]
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 endif::[]
 
 [.abstract-title]
 Abstract
 
 This article describes how to best formulate and submit a problem report to the FreeBSD Project.
 
 '''
 
 toc::[]
 
 [[pr-intro]]
 == Introduction
 
 One of the most frustrating experiences one can have as a software user is to submit a problem report only to have it summarily closed with a terse and unhelpful explanation like "not a bug" or "bogus PR".
 Similarly, one of the most frustrating experiences as a software developer is to be flooded with problem reports that are not really problem reports but requests for support, or that contain little or no information about what the problem is and how to reproduce it.
 
 This document attempts to describe how to write good problem reports.
 What, one asks, is a good problem report? Well, to go straight to the bottom line, a good problem report is one that can be analyzed and dealt with swiftly, to the mutual satisfaction of both user and developer.
 
 Although the primary focus of this article is on FreeBSD problem reports, most of it should apply quite well to other software projects.
 
 Note that this article is organized thematically, not chronologically.
 Read the entire document before submitting a problem report, rather than treating it as a step-by-step tutorial.
 
 [[pr-when]]
 == When to Submit a Problem Report
 
 There are many types of problems, and not all of them should engender a problem report.
 Of course, nobody is perfect, and there will be times when what seems to be a bug in a program is, in fact, a misunderstanding of the syntax for a command or a typographical error in a configuration file (though that in itself may sometimes be indicative of poor documentation or poor error handling in the application).
 There are still many cases where submitting a problem report is clearly _not_ the right course of action, and will only serve to frustrate both the submitter and the developers.
 Conversely, there are cases where it might be appropriate to submit a problem report about something else than a bug-an enhancement or a new feature, for instance.
 
 So how does one determine what is a bug and what is not? As a simple rule of thumb, the problem is _not_ a bug if it can be expressed as a question (usually of the form "How do I do X?" or "Where can I find Y?").
 It is not always quite so black and white, but the question rule covers a large majority of cases.
 When looking for an answer, consider posing the question to the {freebsd-questions}.
 
 Consider these factors when submitting PRs about ports or other software that is not part of FreeBSD itself:
 
 * Please do not submit problem reports that simply state that a newer version of an application is available. Ports maintainers are automatically notified by portscout when a new version of an application becomes available. Actual patches to update a port to the latest version are welcome.
 * For unmaintained ports (`MAINTAINER` is `ports@FreeBSD.org`), a PR without an included patch is unlikely to get picked up by a committer. To become the maintainer of an unmaintained port, submit a PR with the request (patch preferred but not required).
 * In either case, following the process described in link:{porters-handbook}#port-upgrading[Porter's Handbook] will yield the best results. (You might also wish to read link:{contributing}#ports-contributing[Contributing to the FreeBSD Ports Collection].)
 
 A bug that cannot be reproduced can rarely be fixed.
 If the bug only occurred once and you cannot reproduce it, and it does not seem to happen to anybody else, chances are none of the developers will be able to reproduce it or figure out what is wrong.
 That does not mean it did not happen, but it does mean that the chances of your problem report ever leading to a bug fix are very slim.
 To make matters worse, often these kinds of bugs are actually caused by failing hard drives or overheating processors - you should always try to rule out these causes, whenever possible, before submitting a PR.
 
 Next, to decide to whom you should file your problem report, you need to understand that the software that makes up FreeBSD is composed of several different elements:
 
 * Code in the base system that is written and maintained by FreeBSD contributors, such as the kernel, the C library, and the device drivers (categorized as `kern`); the binary utilities (`bin`); the manual pages and documentation (`docs`); and the web pages (`www`). All bugs in these areas should be reported to the FreeBSD developers.
 * Code in the base system that is written and maintained by others, and imported into FreeBSD and adapted. Examples include man:clang[1], and man:sendmail[8]. Most bugs in these areas should be reported to the FreeBSD developers; but in some cases they may need to be reported to the original authors instead if the problems are not FreeBSD-specific.
 * Individual applications that are not in the base system but are instead part of the FreeBSD Ports Collection (category `ports`). Most of these applications are not written by FreeBSD developers; what FreeBSD provides is merely a framework for installing the application. Therefore, only report a problem to the FreeBSD developers when the problem is believed to be FreeBSD-specific; otherwise, report it to the authors of the software.
 
 Then, ascertain whether the problem is timely.
 There are few things that will annoy a developer more than receiving a problem report about a bug she has already fixed.
 
 If the problem is in the base system, first read the FAQ section on link:{faq}#LATEST-VERSION[FreeBSD versions], if you are not already familiar with the topic.
 It is not possible for FreeBSD to fix problems in anything other than certain recent branches of the base system, so filing a bug report about an older version will probably only result in a developer advising you to upgrade to a supported version to see if the problem still recurs.
 The Security Officer team maintains the link:https://www.FreeBSD.org/security/[list of supported versions].
 
 If the problem is in a port, consider filing a bug with the upstream.
 The FreeBSD Project can not fix all bugs in all software.
 
 [[pr-prep]]
 == Preparations
 
 A good rule to follow is to always do a background search before submitting a problem report.
 Maybe the problem has already been reported; maybe it is being discussed on the mailing lists, or recently was; it may even already be fixed in a newer version than what you are running.
 You should therefore check all the obvious places before submitting your problem report.
 For FreeBSD, this means:
 
 * The FreeBSD link:{faq}[Frequently Asked Questions] (FAQ) list. The FAQ attempts to provide answers for a wide range of questions, such as those concerning  link:{faq}#hardware[hardware compatibility], link:{faq}#applications[user applications], and link:{faq}#kernelconfig[kernel configuration].
 * The link:{handbook}#eresources-mail[mailing lists]-if you are not subscribed, use https://www.FreeBSD.org/search/#mailinglists[the searchable archives] on the FreeBSD web site. If the problem has not been discussed on the lists, you might try posting a message about it and waiting a few days to see if someone can spot something that has been overlooked.
 * Optionally, the entire web-use your favorite search engine to locate any references to the problem. You may even get hits from archived mailing lists or newsgroups you did not know of or had not thought to search through.
 * Next, the searchable https://bugs.freebsd.org/bugzilla/query.cgi[FreeBSD PR database] (Bugzilla). Unless the problem is recent or obscure, there is a fair chance it has already been reported.
 * Most importantly, attempt to see if existing documentation in the source base addresses your problem.
-+ 
++
 For the base FreeBSD code, you should carefully study the contents of [.filename]#/usr/src/UPDATING# on your system or the latest version at https://cgit.freebsd.org/src/tree/UPDATING[https://cgit.freebsd.org/src/tree/UPDATING].
 (This is vital information if you are upgrading from one version to another-especially if you are upgrading to the FreeBSD-CURRENT branch).
-+ 
++
 However, if the problem is in something that was installed as a part of the FreeBSD Ports Collection, you should refer to [.filename]#/usr/ports/UPDATING# (for individual ports) or [.filename]#/usr/ports/CHANGES# (for changes that affect the entire Ports Collection).
 https://cgit.freebsd.org/ports/tree/UPDATING[https://cgit.freebsd.org/ports/tree/UPDATING] and https://cgit.freebsd.org/ports/tree/CHANGES[https://cgit.freebsd.org/ports/tree/CHANGES] are also available via cgit.
 
 [[pr-writing]]
 == Writing the Problem Report
 
 Now that you have decided that your issue merits a problem report, and that it is a FreeBSD problem, it is time to write the actual problem report.
 Before we get into the mechanics of the program used to generate and submit PRs, here are some tips and tricks to help make sure that your PR will be most effective.
 
 [[pr-writing-tips]]
 == Tips and Tricks for Writing a Good Problem Report
 
 * _Do not leave the "Summary" line empty._ The PRs go both onto a mailing list that goes all over the world (where the "Summary" is used for the `Subject:` line), but also into a database. Anyone who comes along later and browses the database by synopsis, and finds a PR with a blank subject line, tends just to skip over it. Remember that PRs stay in this database until they are closed by someone; an anonymous one will usually just disappear in the noise.
 * _Avoid using a weak "Summary" line._ You should not assume that anyone reading your PR has any context for your submission, so the more you provide, the better. For instance, what part of the system does the problem apply to? Do you only see the problem while installing, or while running? To illustrate, instead of `Summary: portupgrade is broken`, see how much more informative this seems: `Summary: port ports-mgmt/portupgrade coredumps on -current`. (In the case of ports, it is especially helpful to have both the category and portname in the "Summary" line.)
 * _If you have a patch, say so._ A PR with a patch included is much more likely to be looked at than one without. Please set the `patch` Keyword in Bugzilla.
 * _If you are a maintainer, say so._ If you are maintaining a part of the source code (for instance, an existing port), you definitely should set the "Class" of your PR to `maintainer-update`. This way any committer that handles your PR will not have to check.
 * _Be specific._ The more information you supply about what problem you are having, the better your chance of getting a response.
 
 ** Include the version of FreeBSD you are running (there is a place to put that, see below) and on which architecture. You should include whether you are running from a release (e.g., from a CD-ROM or download), or from a system maintained by Git (and, if so, what hash and branch you are at). If you are tracking the FreeBSD-CURRENT branch, that is the very first thing someone will ask, because fixes (especially for high-profile problems) tend to get committed very quickly, and FreeBSD-CURRENT users are expected to keep up.
 ** Include which global options you have specified in your [.filename]#make.conf#, [.filename]#src.conf#, and [.filename]#src-env.conf#. Given the infinite number of options, not every combination may be fully supported.
 ** If the problem can be reproduced easily, include information that will help a developer to reproduce it themselves. If a problem can be demonstrated with specific input then include an example of that input if possible, and include both the actual and the expected output. If this data is large or cannot be made public, then do try to create a minimal file that exhibits the same issue and that can be included within the PR.
 ** If this is a kernel problem, then be prepared to supply the following information. (You do not have to include these by default, which only tends to fill up the database, but you should include excerpts that you think might be relevant):
 
 *** your kernel configuration (including which hardware devices you have installed)
 *** whether or not you have debugging options enabled (such as `WITNESS`), and if so, whether the problem persists when you change the sense of that option
 *** the full text of any backtrace, panic or other console output, or entries in [.filename]#/var/log/messages#, if any were generated
 *** the output of `pciconf -l` and relevant parts of your `dmesg` output if your problem relates to a specific piece of hardware
 *** the fact that you have read [.filename]#src/UPDATING# and that your problem is not listed there (someone is guaranteed to ask)
 *** whether or not you can run any other kernel as a fallback (this is to rule out hardware-related issues such as failing disks and overheating CPUs, which can masquerade as kernel problems)
 
 ** If this is a ports problem, then be prepared to supply the following information. (You do not have to include these by default, which only tends to fill up the database, but you should include excerpts that you think might be relevant):
 
 *** which ports you have installed
 *** any environment variables that override the defaults in [.filename]#bsd.port.mk#, such as `PORTSDIR`
 *** the fact that you have read [.filename]#ports/UPDATING# and that your problem is not listed there (someone is guaranteed to ask)
 
 * _Avoid vague requests for features._ PRs of the form "someone should really implement something that does so-and-so" are less likely to get results than very specific requests. Remember, the source is available to everyone, so if you want a feature, the best way to ensure it being included is to get to work! Also consider the fact that many things like this would make a better topic for discussion on `freebsd-questions` than an entry in the PR database, as discussed above.
 * _Make sure no one else has already submitted a similar PR._ Although this has already been mentioned above, it bears repeating here. It only take a minute or two to use the web-based search engine at https://bugs.freebsd.org/bugzilla/query.cgi[https://bugs.freebsd.org/bugzilla/query.cgi]. (Of course, everyone is guilty of forgetting to do this now and then.)
 * _Report only one issue per Problem Report._ Avoid including two or more problems within the same report unless they are related. When submitting patches, avoid adding multiple features or fixing multiple bugs in the same PR unless they are closely related-such PRs often take longer to resolve.
 * _Avoid controversial requests._ If your PR addresses an area that has been controversial in the past, you should probably be prepared to not only offer patches, but also justification for why the patches are "The Right Thing To Do". As noted above, a careful search of the mailing lists using the archives at https://www.FreeBSD.org/search/#mailinglists[https://www.FreeBSD.org/search/#mailinglists] is always good preparation.
 * _Be polite._ Almost anyone who would potentially work on your PR is a volunteer. No one likes to be told that they have to do something when they are already doing it for some motivation other than monetary gain. This is a good thing to keep in mind at all times on Open Source projects.
 
 [[pr-writing-before-beginning]]
 == Before Beginning
 
 Similar considerations apply to use of the https://bugs.freebsd.org/bugzilla/enter_bug.cgi[web-based PR submission form].
 Be careful of cut-and-paste operations that might change whitespace or other text formatting.
 
 Finally, if the submission is lengthy, prepare the work offline so that nothing will be lost if there is a problem submitting it.
 
 [[pr-writing-attaching-patches]]
 == Attaching Patches or Files
 
 When attaching a patch, be sure to use either `git diff` or man:diff[1] with the `-u` option to create a unified diff and make sure to specify the Git hash and branch of the repository against which you modified files, so the developers who read your report will be able to apply them easily.
 For problems with the kernel or the base utilities, a patch against FreeBSD-CURRENT (the main Git branch) is preferred since all new code should be applied and tested there first.
 After appropriate or substantial testing has been done, the code will be merged/migrated to the FreeBSD-STABLE branch.
 
 If you attach a patch inline, instead of as an attachment, note that the most common problem by far is the tendency of some email programs to render tabs as spaces, which will completely ruin anything intended to be part of a Makefile.
 
 Do not send patches as attachments using `Content-Transfer-Encoding: quoted-printable`.
 These will perform character escaping and the entire patch will be useless.
 
 Also note that while including small patches in a PR is generally all right-particularly when they fix the problem described in the PR-large patches and especially new code which may require substantial review before committing should be placed on a web or ftp server, and the URL should be included in the PR instead of the patch.
 Patches in email tend to get mangled, and the larger the patch, the harder it will be for interested parties to unmangle it.
 Also, posting a patch on the web allows you to modify it without having to resubmit the entire patch in a followup to the original PR.
 Finally, large patches simply increase the size of the database, since closed PRs are not actually deleted but instead kept and simply marked as complete.
 
 You should also take note that unless you explicitly specify otherwise in your PR or in the patch itself, any patches you submit will be assumed to be licensed under the same terms as the original file you modified.
 
 [[pr-writing-filling-template]]
 == Filling out the Form
 
 [NOTE]
 ====
 The email address you use will become public information and may become available to spammers.
 You should either have spam handling procedures in place, or use a temporary email account.
 However, please note that if you do not use a valid email account at all, we will not be able to ask you questions about your PR.
 ====
 
 When you file a bug, you will find the following fields:
 
 * _Summary:_ Fill this out with a short and accurate description of the problem. The synopsis is used as the subject of the problem report email, and is used in problem report listings and summaries; problem reports with obscure synopses tend to get ignored.
 * _Severity:_ One of `Affects only me`, `Affects some people` or `Affects many people`. Do not overreact; refrain from labeling your problem `Affects many people` unless it really does. FreeBSD developers will not necessarily work on your problem faster if you inflate its importance since there are so many other people who have done exactly that.
 * _Category:_ Choose an appropriate category.
-+ 
++
 The first thing you need to do is to decide what part of the system your problem lies in.
 Remember, FreeBSD is a complete operating system, which installs both a kernel, the standard libraries, many peripheral drivers, and a large number of utilities (the "base system").
 However, there are thousands of additional applications in the Ports Collection.
 You'll first need to decide if the problem is in the base system or something installed via the Ports Collection.
-+ 
++
 Here is a description of the major categories:
 
 ** If a problem is with the kernel, the libraries (such as standard C library `libc`), or a peripheral driver in the base system, in general you will use the `kern` category. (There are a few exceptions; see below). In general these are things that are described in section 2, 3, or 4 of the manual pages.
 ** If a problem is with a binary program such as man:sh[1] or man:mount[8], you will first need to determine whether these programs are in the base system or were added via the Ports Collection. If you are unsure, you can do `whereis _programname_`. FreeBSD's convention for the Ports Collection is to install everything underneath [.filename]#/usr/local#, although this can be overridden by a system administrator. For these, you will use the `ports` category (yes, even if the port's category is `www`; see below). If the location is [.filename]#/bin#, [.filename]#/usr/bin#, [.filename]#/sbin#, or [.filename]#/usr/sbin#, it is part of the base system, and you should use the `bin` category. These are all things that are described in section 1 or 8 of the manual pages.
 ** If you believe that the error is in the startup `(rc)` scripts, or in some kind of other non-executable configuration file, then the right category is `conf` (configuration). These are things that are described in section 5 of the manual pages.
 ** If you have found a problem in the documentation set (articles, books, man pages) or website the correct choice is `docs`.
 +
 [NOTE]
 ====
 if you are having a problem with something from a port named `www/_someportname_`, this nevertheless goes in the `ports` category.
 ====
-+ 
++
 There are a few more specialized categories.
 
 ** If the problem would otherwise be filed in `kern` but has to do with the USB subsystem, the correct choice is `usb`.
 ** If the problem would otherwise be filed in `kern` but has to do with the threading libraries, the correct choice is `threads`.
 ** If the problem would otherwise be in the base system, but has to do with our adherence to standards such as POSIX(R), the correct choice is `standards`.
 ** If you are convinced that the problem will only occur under the processor architecture you are using, select one of the architecture-specific categories: commonly `i386` for Intel-compatible machines in 32-bit mode; `amd64` for AMD machines running in 64-bit mode (this also includes Intel-compatible machines running in EMT64 mode); and less commonly `arm` or `powerpc`.
 +
 [NOTE]
 ====
 These categories are quite often misused for "I do not know" problems. Rather than guessing, please just use `misc`.
 ====
 +
 .Correct Use of Arch-Specific Category
 [example]
 ====
 You have a common PC-based machine, and think you have encountered a problem specific to a particular chipset or a particular motherboard: `i386` is the right category.
 ====
 +
 .Incorrect Use of Arch-Specific Category
 [example]
 ====
 You are having a problem with an add-in peripheral card on a commonly seen bus, or a problem with a particular type of hard disk drive: in this case, it probably applies to more than one architecture, and `kern` is the right category.
 ====
 ** If you really do not know where the problem lies (or the explanation does not seem to fit into the ones above), use the `misc` category. Before you do so, you may wish to ask for help on the {freebsd-questions} first. You may be advised that one of the existing categories really is a better choice.
 * _Environment:_ This should describe, as accurately as possible, the environment in which the problem has been observed. This includes the operating system version, the version of the specific program or file that contains the problem, and any other relevant items such as system configuration, other installed software that influences the problem, etc.-quite simply everything a developer needs to know to reconstruct the environment in which the problem occurs.
 * __Description:__A complete and accurate description of the problem you are experiencing. Try to avoid speculating about the causes of the problem unless you are certain that you are on the right track, as it may mislead a developer into making incorrect assumptions about the problem. It should include the actions you need to take to reproduce the problem. If you know any workaround, include it. It not only helps other people with the same problem work around it, but may also help a developer understand the cause for the problem.
 
 [[pr-followup]]
 == Follow-up
 
 Once the problem report has been filed, you will receive a confirmation by email which will include the tracking number that was assigned to your problem report and a URL you can use to check its status.
 With a little luck, someone will take an interest in your problem and try to address it, or, as the case may be, explain why it is not a problem.
 You will be automatically notified of any change of status, and you will receive copies of any comments or patches someone may attach to your problem report's audit trail.
 
 If someone requests additional information from you, or you remember or discover something you did not mention in the initial report, please submit a follow up.
 The number one reason for a bug not getting fixed is lack of communication with the originator.
 The easiest way is to use the comment option on the individual PR's web page, which you can reach from the https://bugs.freebsd.org/bugzilla/query.cgi[PR search page].
 
 If the problem report remains open after the problem has gone away, just add a comment saying that the problem report can be closed, and, if possible, explaining how or when the problem was fixed.
 
 Sometimes there is a delay of a week or two where the problem report remains untouched, not assigned or commented on by anyone.
 This can happen when there is an increased problem report backlog or during a holiday season.
 When a problem report has not received attention after several weeks, it is worth finding a committer particularly interested in working on it.
 
 There are a few ways to do so, ideally in the following order, with a few days between attempting each communication channel:
 
 * Find the relevant FreeBSD mailing list for the problem report from the link:{handbook}#eresources-mail[list in the Handbook] and send a message to that list asking about assistance or comments on the problem report.
 * Join the relevant IRC channels. A partial listing is here: https://wiki.freebsd.org/IrcChannels[]. Inform the people in that channel about the problem report and ask for assistance. Be patient and stay in the channel after posting, so that the people from different time zones around the world have a chance to catch up.
 * Find committers interested in the problem that was reported. If the problem was in a particular tool, binary, port, document, or source file, check the https://cgit.FreeBSD.org[Git Repository]. Locate the last few committers who made substantive changes to the file, and try to reach them via IRC or email. A list of committers and their emails can be found in the link:{contributors}[Contributors to FreeBSD] article.
 
 Remember that these people are volunteers, just like maintainers and users, so they might not be immediately available to assist with the problem report. 
 Patience and consistency in the follow-ups is highly advised and appreciated.
 With enough care and effort dedicated to that follow-up process, finding a committer to take care of the problem report is just a matter of time.
 
 [[pr-problems]]
 == If There Are Problems
 
 If you found an issue with the bug system, file a bug! There is a category for exactly this purpose.
 If you are unable to do so, contact the bug wranglers at  mailto:bugmeister@FreeBSD.org[bugmeister@FreeBSD.org].
 
 [[pr-further]]
 == Further Reading
 
 This is a list of resources relevant to the proper writing and processing of problem reports.
 It is by no means complete.
 
 * https://github.com/smileytechguy/reporting-bugs-effectively/blob/master/ENGLISH.md[How to Report Bugs Effectively]-an excellent essay by Simon G. Tatham on composing useful (non-FreeBSD-specific) problem reports.
 * link:{pr-guidelines}[Problem Report Handling Guidelines]-valuable insight into how problem reports are handled by the FreeBSD developers.
diff --git a/documentation/content/en/articles/serial-uart/_index.adoc b/documentation/content/en/articles/serial-uart/_index.adoc
index 084f4493d6..60ee8c73b4 100644
--- a/documentation/content/en/articles/serial-uart/_index.adoc
+++ b/documentation/content/en/articles/serial-uart/_index.adoc
@@ -1,1177 +1,1177 @@
 ---
 title: Serial and UART Tutorial
 authors:
   - author: Frank Durda
     email: uhclem@FreeBSD.org
 description: Detailed information about the use of serial ports and UART with FreeBSD
 trademarks: ["freebsd", "microsoft", "general"]
 tags: ["Serial", "hardware", "UART", "Tutorial", "FreeBSD"]
 ---
 
 = Serial and UART Tutorial
 :doctype: article
 :toc: macro
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 :icons: font
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 [.abstract-title]
 Abstract
 
 This article talks about using serial hardware with FreeBSD.
 
 '''
 
 toc::[]
 
 [[uart]]
 == The UART: What it is and how it works
 
 _Copyright (R) 1996 `{uhclem}`, All Rights Reserved. 13 January 1996._
 
 The Universal Asynchronous Receiver/Transmitter (UART) controller is the key component of the serial communications subsystem of a computer.
 The UART takes bytes of data and transmits the individual bits in a sequential fashion.
 At the destination, a second UART re-assembles the bits into complete bytes.
 
 Serial transmission is commonly used with modems and for non-networked communication between computers, terminals and other devices.
 
 There are two primary forms of serial transmission: Synchronous and Asynchronous.
 Depending on the modes that are supported by the hardware, the name of the communication sub-system will usually include a `A` if it supports Asynchronous communications, and a `S` if it supports Synchronous communications.
 Both forms are described below.
 
 Some common acronyms are:
 
 [.blockquote]
 UART Universal Asynchronous Receiver/Transmitter
 
 [.blockquote]
 USART Universal Synchronous-Asynchronous Receiver/Transmitter
 
 === Synchronous Serial Transmission
 
 Synchronous serial transmission requires that the sender and receiver share a clock with one another, or that the sender provide a strobe or other timing signal so that the receiver knows when to "read" the next bit of the data.
 In most forms of serial Synchronous communication, if there is no data available at a given instant to transmit, a fill character must be sent instead so that data is always being transmitted.
 Synchronous communication is usually more efficient because only data bits are transmitted between sender and receiver, and synchronous communication can be more costly if extra wiring and circuits are required to share a clock signal between the sender and receiver.
 
 A form of Synchronous transmission is used with printers and fixed disk devices in that the data is sent on one set of wires while a clock or strobe is sent on a different wire.
 Printers and fixed disk devices are not normally serial devices because most fixed disk interface standards send an entire word of data for each clock or strobe signal by using a separate wire for each bit of the word.
 In the PC industry, these are known as Parallel devices.
 
 The standard serial communications hardware in the PC does not support Synchronous operations.
 This mode is described here for comparison purposes only.
 
 === Asynchronous Serial Transmission
 
 Asynchronous transmission allows data to be transmitted without the sender having to send a clock signal to the receiver.
 Instead, the sender and receiver must agree on timing parameters in advance and special bits are added to each word which are used to synchronize the sending and receiving units.
 
 When a word is given to the UART for Asynchronous transmissions, a bit called the "Start Bit" is added to the beginning of each word that is to be transmitted.
 The Start Bit is used to alert the receiver that a word of data is about to be sent, and to force the clock in the receiver into synchronization with the clock in the transmitter.
 These two clocks must be accurate enough to not have the frequency drift by more than 10% during the transmission of the remaining bits in the word.
 (This requirement was set in the days of mechanical teleprinters and is easily met by modern electronic equipment.)
 
 After the Start Bit, the individual bits of the word of data are sent, with the Least Significant Bit (LSB) being sent first.
 Each bit in the transmission is transmitted for exactly the same amount of time as all of the other bits, and the receiver "looks" at the wire at approximately halfway through the period assigned to each bit to determine if the bit is a `1` or a `0`.
 For example, if it takes two seconds to send each bit, the receiver will examine the signal to determine if it is a `1` or a `0` after one second has passed, then it will wait two seconds and then examine the value of the next bit, and so on.
 
 The sender does not know when the receiver has "looked" at the value of the bit.
 The sender only knows when the clock says to begin transmitting the next bit of the word.
 
 When the entire data word has been sent, the transmitter may add a Parity Bit that the transmitter generates.
 The Parity Bit may be used by the receiver to perform simple error checking.
 Then at least one Stop Bit is sent by the transmitter.
 
 When the receiver has received all of the bits in the data word, it may check for the Parity Bits (both sender and receiver must agree on whether a Parity Bit is to be used), and then the receiver looks for a Stop Bit.
 If the Stop Bit does not appear when it is supposed to, the UART considers the entire word to be garbled and will report a Framing Error to the host processor when the data word is read.
 The usual cause of a Framing Error is that the sender and receiver clocks were not running at the same speed, or that the signal was interrupted.
 
 Regardless of whether the data was received correctly or not, the UART automatically discards the Start, Parity and Stop bits.
 If the sender and receiver are configured identically, these bits are not passed to the host.
 
 If another word is ready for transmission, the Start Bit for the new word can be sent as soon as the Stop Bit for the previous word has been sent.
 
 As asynchronous data is "self synchronizing", if there is no data to transmit, the transmission line can be idle.
 
 === Other UART Functions
 
 In addition to the basic job of converting data from parallel to serial for transmission and from serial to parallel on reception, a UART will usually provide additional circuits for signals that can be used to indicate the state of the transmission media, and to regulate the flow of data in the event that the remote device is not prepared to accept more data.
 For example, when the device connected to the UART is a modem, the modem may report the presence of a carrier on the phone line while the computer may be able to instruct the modem to reset itself or to not take calls by raising or lowering one more of these extra signals.
 The function of each of these additional signals is defined in the EIA RS232-C standard.
 
 === The RS232-C and V.24 Standards
 
 In most computer systems, the UART is connected to circuitry that generates signals that comply with the EIA RS232-C specification.
 There is also a CCITT standard named V.24 that mirrors the specifications included in RS232-C.
 
 ==== RS232-C Bit Assignments (Marks and Spaces)
 
 In RS232-C, a value of `1` is called a `Mark` and a value of `0` is called a `Space`.
 When a communication line is idle, the line is said to be "Marking", or transmitting continuous `1` values.
 
 The Start bit always has a value of `0` (a Space).
 The Stop Bit always has a value of `1` (a Mark).
 This means that there will always be a Mark (1) to Space (0) transition on the line at the start of every word, even when multiple word are transmitted back to back.
 This guarantees that sender and receiver can resynchronize their clocks regardless of the content of the data bits that are being transmitted.
 
 The idle time between Stop and Start bits does not have to be an exact multiple (including zero) of the bit rate of the communication link, but most UARTs are designed this way for simplicity.
 
 In RS232-C, the "Marking" signal (a `1`) is represented by a voltage between -2 VDC and -12 VDC, and a "Spacing" signal (a `0`) is represented by a voltage between 0 and +12 VDC.
 The transmitter is supposed to send +12 VDC or -12 VDC, and the receiver is supposed to allow for some voltage loss in long cables.
 Some transmitters in low power devices (like portable computers) sometimes use only +5 VDC and -5 VDC, but these values are still acceptable to a RS232-C receiver, provided that the cable lengths are short.
 
 ==== RS232-C Break Signal
 
 RS232-C also specifies a signal called a `Break`, which is caused by sending continuous Spacing values (no Start or Stop bits).
 When there is no electricity present on the data circuit, the line is considered to be sending `Break`.
 
 The `Break` signal must be of a duration longer than the time it takes to send a complete byte plus Start, Stop and Parity bits.
 Most UARTs can distinguish between a Framing Error and a Break, but if the UART cannot do this, the Framing Error detection can be used to identify Breaks.
 
 In the days of teleprinters, when numerous printers around the country were wired in series (such as news services), any unit could cause a `Break` by temporarily opening the entire circuit so that no current flowed.
 This was used to allow a location with urgent news to interrupt some other location that was currently sending information.
 
 In modern systems there are two types of Break signals.
 If the Break is longer than 1.6 seconds, it is considered a "Modem Break", and some modems can be programmed to terminate the conversation and go on-hook or enter the modems' command mode when the modem detects this signal.
 If the Break is smaller than 1.6 seconds, it signifies a Data Break and it is up to the remote computer to respond to this signal.
 Sometimes this form of Break is used as an Attention or Interrupt signal and sometimes is accepted as a substitute for the ASCII CONTROL-C character.
 
 Marks and Spaces are also equivalent to "Holes" and "No Holes" in paper tape systems.
 
 [NOTE]
 ====
 Breaks cannot be generated from paper tape or from any other byte value, since bytes are always sent with Start and Stop bit.
 The UART is usually capable of generating the continuous Spacing signal in response to a special command from the host processor.
 ====
 
 ==== RS232-C DTE and DCE Devices
 
 The RS232-C specification defines two types of equipment: the Data Terminal Equipment (DTE) and the Data Carrier Equipment (DCE).
 Usually, the DTE device is the terminal (or computer), and the DCE is a modem.
 Across the phone line at the other end of a conversation, the receiving modem is also a DCE device and the computer that is connected to that modem is a DTE device.
 The DCE device receives signals on the pins that the DTE device transmits on, and vice versa.
 
 When two devices that are both DTE or both DCE must be connected together without a modem or a similar media translator between them, a NULL modem must be used.
 The NULL modem electrically re-arranges the cabling so that the transmitter output is connected to the receiver input on the other device, and vice versa.
 Similar translations are performed on all of the control signals so that each device will see what it thinks are DCE (or DTE) signals from the other device.
 
 The number of signals generated by the DTE and DCE devices are not symmetrical.
 The DTE device generates fewer signals for the DCE device than the DTE device receives from the DCE.
 
 ==== RS232-C Pin Assignments
 
 The EIA RS232-C specification (and the ITU equivalent, V.24) calls for a twenty-five pin connector (usually a DB25) and defines the purpose of most of the pins in that connector.
 
 In the IBM Personal Computer and similar systems, a subset of RS232-C signals are provided via nine pin connectors (DB9).
 The signals that are not included on the PC connector deal mainly with synchronous operation, and this transmission mode is not supported by the UART that IBM selected for use in the IBM PC.
 
 Depending on the computer manufacturer, a DB25, a DB9, or both types of connector may be used for RS232-C communications.
 (The IBM PC also uses a DB25 connector for the parallel printer interface which causes some confusion.)
 
 Below is a table of the RS232-C signal assignments in the DB25 and DB9 connectors.
 
 [.informaltable]
 [cols="1,1,1,1,1,1,1", frame="none", options="header"]
 |===
 | DB25 RS232-C Pin
 | DB9 IBM PC Pin
 | EIA Circuit Symbol
 | CCITT Circuit Symbol
 | Common Name
 | Signal Source
 | Description
 
 |1
 |-
 |AA
 |101
 |PG/FG
 |-
 |Frame/Protective Ground
 
 |2
 |3
 |BA
 |103
 |TD
 |DTE
 |Transmit Data
 
 |3
 |2
 |BB
 |104
 |RD
 |DCE
 |Receive Data
 
 |4
 |7
 |CA
 |105
 |RTS
 |DTE
 |Request to Send
 
 |5
 |8
 |CB
 |106
 |CTS
 |DCE
 |Clear to Send
 
 |6
 |6
 |CC
 |107
 |DSR
 |DCE
 |Data Set Ready
 
 |7
 |5
 |AV
 |102
 |SG/GND
 |-
 |Signal Ground
 
 |8
 |1
 |CF
 |109
 |DCD/CD
 |DCE
 |Data Carrier Detect
 
 |9
 |-
 |-
 |-
 |-
 |-
 |Reserved for Test
 
 |10
 |-
 |-
 |-
 |-
 |-
 |Reserved for Test
 
 |11
 |-
 |-
 |-
 |-
 |-
 |Reserved for Test
 
 |12
 |-
 |CI
 |122
 |SRLSD
 |DCE
 |Sec. Recv. Line Signal Detector
 
 |13
 |-
 |SCB
 |121
 |SCTS
 |DCE
 |Secondary Clear to Send
 
 |14
 |-
 |SBA
 |118
 |STD
 |DTE
 |Secondary Transmit Data
 
 |15
 |-
 |DB
 |114
 |TSET
 |DCE
 |Trans. Sig. Element Timing
 
 |16
 |-
 |SBB
 |119
 |SRD
 |DCE
 |Secondary Received Data
 
 |17
 |-
 |DD
 |115
 |RSET
 |DCE
 |Receiver Signal Element Timing
 
 |18
 |-
 |-
 |141
 |LOOP
 |DTE
 |Local Loopback
 
 |19
 |-
 |SCA
 |120
 |SRS
 |DTE
 |Secondary Request to Send
 
 |20
 |4
 |CD
 |108.2
 |DTR
 |DTE
 |Data Terminal Ready
 
 |21
 |-
 |-
 |-
 |RDL
 |DTE
 |Remote Digital Loopback
 
 |22
 |9
 |CE
 |125
 |RI
 |DCE
 |Ring Indicator
 
 |23
 |-
 |CH
 |111
 |DSRS
 |DTE
 |Data Signal Rate Selector
 
 |24
 |-
 |DA
 |113
 |TSET
 |DTE
 |Trans. Sig. Element Timing
 
 |25
 |-
 |-
 |142
 |-
 |DCE
 |Test Mode
 |===
 
 === Bits, Baud and Symbols
 
 Baud is a measurement of transmission speed in asynchronous communication.
 Due to advances in modem communication technology, this term is frequently misused when describing the data rates in newer devices.
 
 Traditionally, a Baud Rate represents the number of bits that are actually being sent over the media, not the amount of data that is actually moved from one DTE device to the other.
 The Baud count includes the overhead bits Start, Stop and Parity that are generated by the sending UART and removed by the receiving UART.
 This means that seven-bit words of data actually take 10 bits to be completely transmitted.
 Therefore, a modem capable of moving 300 bits per second from one place to another can normally only move 30 7-bit words if Parity is used and one Start and Stop bit are present.
 
 If 8-bit data words are used and Parity bits are also used, the data rate falls to 27.27 words per second, because it now takes 11 bits to send the eight-bit words, and the modem still only sends 300 bits per second.
 
 The formula for converting bytes per second into a baud rate and vice versa was simple until error-correcting modems came along.
 These modems receive the serial stream of bits from the UART in the host computer (even when internal modems are used the data is still frequently serialized) and converts the bits back into bytes.
 These bytes are then combined into packets and sent over the phone line using a Synchronous transmission method.
 This means that the Stop, Start, and Parity bits added by the UART in the DTE (the computer) were removed by the modem before transmission by the sending modem.
 When these bytes are received by the remote modem, the remote modem adds Start, Stop and Parity bits to the words, converts them to a serial format and then sends them to the receiving UART in the remote computer, who then strips the Start, Stop and Parity bits.
 
 The reason all these extra conversions are done is so that the two modems can perform error correction, which means that the receiving modem is able to ask the sending modem to resend a block of data that was not received with the correct checksum.
 This checking is handled by the modems, and the DTE devices are usually unaware that the process is occurring.
 
 By striping the Start, Stop and Parity bits, the additional bits of data that the two modems must share between themselves to perform error-correction are mostly concealed from the effective transmission rate seen by the sending and receiving DTE equipment.
 For example, if a modem sends ten 7-bit words to another modem without including the Start, Stop and Parity bits, the sending modem will be able to add 30 bits of its own information that the receiving modem can use to do error-correction without impacting the transmission speed of the real data.
 
 The use of the term Baud is further confused by modems that perform compression.
 A single 8-bit word passed over the telephone line might represent a dozen words that were transmitted to the sending modem.
 The receiving modem will expand the data back to its original content and pass that data to the receiving DTE.
 
 Modern modems also include buffers that allow the rate that bits move across the phone line (DCE to DCE) to be a different speed than the speed that the bits move between the DTE and DCE on both ends of the conversation.
 Normally the speed between the DTE and DCE is higher than the DCE to DCE speed because of the use of compression by the modems.
 
 As the number of bits needed to describe a byte varied during the trip between the two machines plus the differing bits-per-seconds speeds that are used present on the DTE-DCE and DCE-DCE links, the usage of the term Baud to describe the overall communication speed causes problems and can misrepresent the true transmission speed.
 So Bits Per Second (bps) is the correct term to use to describe the transmission rate seen at the DCE to DCE interface and Baud or Bits Per Second are acceptable terms to use when a connection is made between two systems with a wired connection, or if a modem is in use that is not performing error-correction or compression.
 
 Modern high speed modems (2400, 9600, 14,400, and 19,200bps) in reality still operate at or below 2400 baud, or more accurately, 2400 Symbols per second.
 High speed modem are able to encode more bits of data into each Symbol using a technique called Constellation Stuffing, which is why the effective bits per second rate of the modem is higher, but the modem continues to operate within the limited audio bandwidth that the telephone system provides.
 Modems operating at 28,800 and higher speeds have variable Symbol rates, but the technique is the same.
 
 === The IBM Personal Computer UART
 
 Starting with the original IBM Personal Computer, IBM selected the National Semiconductor INS8250 UART for use in the IBM PC Parallel/Serial Adapter. 
 Subsequent generations of compatible computers from IBM and other vendors continued to use the INS8250 or improved versions of the National Semiconductor UART family.
 
 ==== National Semiconductor UART Family Tree
 
 There have been several versions and subsequent generations of the INS8250 UART. Each major version is described below.
 
 [.programlisting]
 ....
 INS8250  -> INS8250B
   \
    \
     \-> INS8250A -> INS82C50A
              \
               \
                \-> NS16450 -> NS16C450
                         \
                          \
                           \-> NS16550 -> NS16550A -> PC16550D
 ....
 
 INS8250::
 This part was used in the original IBM PC and IBM PC/XT.
 The original name for this part was the INS8250 ACE (Asynchronous Communications Element) and it is made from NMOS technology.
 +
 The 8250 uses eight I/O ports and has a one-byte send and a one-byte receive buffer.
 This original UART has several race conditions and other flaws.
 The original IBM BIOS includes code to work around these flaws, but this made the BIOS dependent on the flaws being present, so subsequent parts like the 8250A, 16450 or 16550 could not be used in the original IBM PC or IBM PC/XT.
 INS8250-B::
 This is the slower speed of the INS8250 made from NMOS technology.
 It contains the same problems as the original INS8250.
 
 INS8250A::
 An improved version of the INS8250 using XMOS technology with various functional flaws corrected.
 The INS8250A was used initially in PC clone computers by vendors who used "clean" BIOS designs.
 Due to the corrections in the chip, this part could not be used with a BIOS compatible with the INS8250 or INS8250B.
 
 INS82C50A::
 This is a CMOS version (low power consumption) of the INS8250A and has similar functional characteristics.
 
 NS16450::
 Same as NS8250A with improvements so it can be used with faster CPU bus designs.
 IBM used this part in the IBM AT and updated the IBM BIOS to no longer rely on the bugs in the INS8250.
 
 NS16C450::
 This is a CMOS version (low power consumption) of the NS16450.
 
 NS16550::
 Same as NS16450 with a 16-byte send and receive buffer but the buffer design was flawed and could not be reliably be used.
 
 NS16550A::
 Same as NS16550 with the buffer flaws corrected.
 The 16550A and its successors have become the most popular UART design in the PC industry, mainly due to its ability to reliably handle higher data rates on operating systems with sluggish interrupt response times.
 
 NS16C552::
 This component consists of two NS16C550A CMOS UARTs in a single package.
 
 PC16550D::
 Same as NS16550A with subtle flaws corrected.
 This is revision D of the 16550 family and is the latest design available from National Semiconductor.
 
 ==== The NS16550AF and the PC16550D are the same thing
 
 National reorganized their part numbering system a few years ago, and the NS16550AFN no longer exists by that name.
 (If you have a NS16550AFN, look at the date code on the part, which is a four digit number that usually starts with a nine.
 The first two digits of the number are the year, and the last two digits are the week in that year when the part was packaged.
 If you have a NS16550AFN, it is probably a few years old.)
 
 The new numbers are like PC16550DV, with minor differences in the suffix letters depending on the package material and its shape.
 (A description of the numbering system can be found below.)
 
 It is important to understand that in some stores, you may pay $15(US) for a NS16550AFN made in 1990 and in the next bin are the new PC16550DN parts with minor fixes that National has made since the AFN part was in production, the PC16550DN was probably made in the past six months and it costs half (as low as $5(US) in volume) as much as the NS16550AFN because they are readily available.
 
 As the supply of NS16550AFN chips continues to shrink, the price will probably continue to increase until more people discover and accept that the PC16550DN really has the same function as the old part number.
 
 ==== National Semiconductor Part Numbering System
 
 The older NS``__nnnnnrqp__`` part numbers are now of the format PC``__nnnnnrgp__``.
 
 The `_r_` is the revision field. The current revision of the 16550 from National Semiconductor is `D`.
 
 The `_p_` is the package-type field. The types are:
 
 [.informaltable]
 [cols="1,1,1", frame="none"]
 |===
 
 |"F"
 |QFP
 |(quad flat pack) L lead type
 
 |"N"
 |DIP
 |(dual inline package) through hole straight lead type
 
 |"V"
 |LPCC
 |(lead plastic chip carrier) J lead type
 |===
 
 The _g_ is the product grade field.
 If an `I` precedes the package-type letter, it indicates an "industrial" grade part, which has higher specs than a standard part but not as high as Military Specification (Milspec) component.
 This is an optional field.
 
 So what we used to call a NS16550AFN (DIP Package) is now called a PC16550DN or PC16550DIN.
 
 === Other Vendors and Similar UARTs
 
 Over the years, the 8250, 8250A, 16450 and 16550 have been licensed or copied by other chip vendors.
 In the case of the 8250, 8250A and 16450, the exact circuit (the "megacell") was licensed to many vendors, including Western Digital and Intel.
 Other vendors reverse-engineered the part or produced emulations that had similar behavior.
 
 In internal modems, the modem designer will frequently emulate the 8250A/16450 with the modem microprocessor, and the emulated UART will frequently have a hidden buffer consisting of several hundred bytes.
 Due to the size of the buffer, these emulations can be as reliable as a 16550A in their ability to handle high speed data.
 However, most operating systems will still report that the UART is only a 8250A or 16450, and may not make effective use of the extra buffering present in the emulated UART unless special drivers are used.
 
 Some modem makers are driven by market forces to abandon a design that has hundreds of bytes of buffer and instead use a 16550A UART so that the product will compare favorably in market comparisons even though the effective performance may be lowered by this action.
 
 A common misconception is that all parts with "16550A" written on them are identical in performance.
 There are differences, and in some cases, outright flaws in most of these 16550A clones.
 
 When the NS16550 was developed, the National Semiconductor obtained several patents on the design and they also limited licensing, making it harder for other vendors to provide a chip with similar features.
 As a result of the patents, reverse-engineered designs and emulations had to avoid infringing the claims covered by the patents.
 Subsequently, these copies almost never perform exactly the same as the NS16550A or PC16550D, which are the parts most computer and modem makers want to buy but are sometimes unwilling to pay the price required to get the genuine part.
 
 Some of the differences in the clone 16550A parts are unimportant, while others can prevent the device from being used at all with a given operating system or driver.
 These differences may show up when using other drivers, or when particular combinations of events occur that were not well tested or considered in the Windows(R) driver.
 This is because most modem vendors and 16550-clone makers use the Microsoft drivers from Windows(R) for Workgroups 3.11 and the Microsoft(R) MS-DOS(R) utility as the primary tests for compatibility with the NS16550A.
 This over-simplistic criteria means that if a different operating system is used, problems could appear due to subtle differences between the clones and genuine components.
 
 National Semiconductor has made available a program named COMTEST that performs compatibility tests independent of any OS drivers.
 It should be remembered that the purpose of this type of program is to demonstrate the flaws in the products of the competition, so the program will report major as well as extremely subtle differences in behavior in the part being tested.
 
 In a series of tests performed by the author of this document in 1994, components made by National Semiconductor, TI, StarTech, and CMD as well as megacells and emulations embedded in internal modems were tested with COMTEST. A difference count for some of these components is listed below.
 Since these tests were performed in 1994, they may not reflect the current performance of the given product from a vendor.
 
 It should be noted that COMTEST normally aborts when an excessive number or certain types of problems have been detected.
 As part of this testing, COMTEST was modified so that it would not abort no matter how many differences were encountered.
 
 [.informaltable]
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Vendor
 | Part Number
 | Errors (aka "differences" reported)
 
 |National
 |(PC16550DV)
 |0
 
 |National
 |(NS16550AFN)
 |0
 
 |National
 |(NS16C552V)
 |0
 
 |TI
 |(TL16550AFN)
 |3
 
 |CMD
 |(16C550PE)
 |19
 
 |StarTech
 |(ST16C550J)
 |23
 
 |Rockwell
 |Reference modem with internal 16550 or an emulation (RC144DPi/C3000-25)
 |117
 
 |Sierra
 |Modem with an internal 16550 (SC11951/SC11351)
 |91
 |===
 
 [NOTE]
 ====
 To date, the author of this document has not found any non-National parts that report zero differences using the COMTEST program.
 It should also be noted that National has had five versions of the 16550 over the years and the newest parts behave a bit differently than the classic NS16550AFN that is considered the benchmark for functionality.
 COMTEST appears to turn a blind eye to the differences within the National product line and reports no errors on the National parts (except for the original 16550) even when there are official erratas that describe bugs in the A, B and C revisions of the parts, so this bias in COMTEST must be taken into account.
 ====
 
 It is important to understand that a simple count of differences from COMTEST does not reveal a lot about what differences are important and which are not.
 For example, about half of the differences reported in the two modems listed above that have internal UARTs were caused by the clone UARTs not supporting five- and six-bit character modes.
 The real 16550, 16450, and 8250 UARTs all support these modes and COMTEST checks the functionality of these modes so over fifty differences are reported.
 However, almost no modern modem supports five- or six-bit characters, particularly those with error-correction and compression capabilities.
 This means that the differences related to five- and six-bit character modes can be discounted.
 
 Many of the differences COMTEST reports have to do with timing.
 In many of the clone designs, when the host reads from one port, the status bits in some other port may not update in the same amount of time (some faster, some slower) as a _real_ NS16550AFN and COMTEST looks for these differences.
 This means that the number of differences can be misleading in that one device may only have one or two differences but they are extremely serious, and some other device that updates the status registers faster or slower than the reference part (that would probably never affect the operation of a properly written driver) could have dozens of differences reported.
 
 COMTEST can be used as a screening tool to alert the administrator to the presence of potentially incompatible components that might cause problems or have to be handled as a special case.
 
 If you run COMTEST on a 16550 that is in a modem or a modem is attached to the serial port, you need to first issue a ATE0&W command to the modem so that the modem will not echo any of the test characters.
 If you forget to do this, COMTEST will report at least this one difference:
 
 [source,shell]
 ....
 Error (6)...Timeout interrupt failed: IIR = c1  LSR = 61
 ....
 
 === 8250/16450/16550 Registers
 
 The 8250/16450/16550 UART occupies eight contiguous I/O port addresses.
 In the IBM PC, there are two defined locations for these eight ports and they are known collectively as [.filename]#COM1# and [.filename]#COM2#.
 The makers of PC-clones and add-on cards have created two additional areas known as [.filename]#COM3# and [.filename]#COM4#, but these extra COM ports conflict with other hardware on some systems.
 The most common conflict is with video adapters that provide IBM 8514 emulation.
 
 [.filename]#COM1# is located from 0x3f8 to 0x3ff and normally uses IRQ 4.
 [.filename]#COM2# is located from 0x2f8 to 0x2ff and normally uses IRQ 3.
 [.filename]#COM3# is located from 0x3e8 to 0x3ef and has no standardized IRQ.
 [.filename]#COM4# is located from 0x2e8 to 0x2ef and has no standardized IRQ.
 
 A description of the I/O ports of the 8250/16450/16550 UART is provided below.
 
 [.informaltable]
 [cols="10%,10%,80%", frame="none", options="header"]
 |===
 | I/O Port
 | Access Allowed
 | Description
 
 |+0x00
 |write (DLAB==0)
 |
 
 Transmit Holding Register (THR).
 
 Information written to this port are treated as data words and will be transmitted by the UART.
 
 |+0x00
 |read (DLAB==0)
 |
 
 Receive Buffer Register (RBR).
 
 Any data words received by the UART form the serial link are accessed by the host by reading this port.
 
 |+0x00
 |write/read (DLAB==1)
 |
 
 Divisor Latch LSB (DLL)
 
 This value will be divided from the master input clock (in the IBM PC, the master clock is 1.8432MHz) and the resulting clock will determine the baud rate of the UART. This register holds bits 0 thru 7 of the divisor.
 
 |+0x01
 |write/read (DLAB==1)
 |
 
 Divisor Latch MSB (DLH)
 
 This value will be divided from the master input clock (in the IBM PC, the master clock is 1.8432MHz) and the resulting clock will determine the baud rate of the UART. This register holds bits 8 thru 15 of the divisor.
 
 |+0x01
 |write/read (DLAB==0)
 |Interrupt Enable Register (IER) +
 
 The 8250/16450/16550 UART classifies events into one of four categories. Each category can be configured to generate an interrupt when any of the events occurs. The 8250/16450/16550 UART generates a single external interrupt signal regardless of how many events in the enabled categories have occurred. It is up to the host processor to respond to the interrupt and then poll the enabled interrupt categories (usually all categories have interrupts enabled) to determine the true cause(s) of the interrupt. +
 Bit 7 -> Reserved, always 0. +
 Bit 6 -> Reserved, always 0. +
 Bit 5 -> Reserved, always 0. +
 Bit 4 -> Reserved, always 0. +
 Bit 3 -> Enable Modem Status Interrupt (EDSSI). Setting this bit to "1" allows the UART to generate an interrupt when a change occurs on one or more of the status lines. +
 Bit 2 -> Enable Receiver Line Status Interrupt (ELSI) Setting this bit to "1" causes the UART to generate an interrupt when the an error (or a BREAK signal) has been detected in the incoming data. +
 Bit 1 -> Enable Transmitter Holding Register Empty Interrupt (ETBEI) Setting this bit to "1" causes the UART to generate an interrupt when the UART has room for one or more additional characters that are to be transmitted. +
 Bit 0 -> Enable Received Data Available Interrupt (ERBFI) Setting this bit to "1" causes the UART to generate an interrupt when the UART has received enough characters to exceed the trigger level of the FIFO, or the FIFO timer has expired (stale data), or a single character has been received when the FIFO is disabled.
 
 |+0x02
 |write
 |FIFO Control Register (FCR) (This port does not exist on the 8250 and 16450 UART.) +
 Bit 7 -> Receiver Trigger Bit #1 +
 Bit 6 -> Receiver Trigger Bit #0 +
 
 These two bits control at what point the receiver is to generate an interrupt when the FIFO is active. +
 7 6 How many words are received before an interrupt is generated +
 0 0 1 +
 0 1 4 +
 1 0 8 +
 1 1 14 +
 Bit 5 -> Reserved, always 0. +
 Bit 4 -> Reserved, always 0. +
 Bit 3 -> DMA Mode Select. If Bit 0 is set to "1" (FIFOs enabled), setting this bit changes the operation of the -RXRDY and -TXRDY signals from Mode 0 to Mode 1. +
 Bit 2 -> Transmit FIFO Reset. When a "1" is written to this bit, the contents of the FIFO are discarded. Any word currently being transmitted will be sent intact. This function is useful in aborting transfers. +
 Bit 1 -> Receiver FIFO Reset. When a "1" is written to this bit, the contents of the FIFO are discarded. Any word currently being assembled in the shift register will be received intact. +
 Bit 0 -> 16550 FIFO Enable. When set, both the transmit and receive FIFOs are enabled. Any contents in the holding register, shift registers or FIFOs are lost when FIFOs are enabled or disabled. +
 
 |+0x02
 |read
 |Interrupt Identification Register +
 Bit 7 -> FIFOs enabled. On the 8250/16450 UART, this bit is zero. +
 Bit 6 -> FIFOs enabled. On the 8250/16450 UART, this bit is zero. +
 Bit 5 -> Reserved, always 0. +
 Bit 4 -> Reserved, always 0. +
 Bit 3 -> Interrupt ID Bit #2. On the 8250/16450 UART, this bit is zero. +
 Bit 2 -> Interrupt ID Bit #1 +
 Bit 1 -> Interrupt ID Bit #0.These three bits combine to report the category of event that caused the interrupt that is in progress. These categories have priorities, so if multiple categories of events occur at the same time, the UART will report the more important events first and the host must resolve the events in the order they are reported. All events that caused the current interrupt must be resolved before any new interrupts will be generated. (This is a limitation of the PC architecture.) +
 2 1 0 Priority Description +
 0 1 1 First Received Error (OE, PE, BI, or FE) +
 0 1 0 Second Received Data Available +
 1 1 0 Second Trigger level identification (Stale data in receive buffer) +
 0 0 1 Third Transmitter has room for more words (THRE) +
 0 0 0 Fourth Modem Status Change (-CTS, -DSR, -RI, or -DCD) +
 Bit 0 -> Interrupt Pending Bit. If this bit is set to "0", then at least one interrupt is pending.
 
 |+0x03
 |write/read
 |Line Control Register (LCR) +
 Bit 7 -> Divisor Latch Access Bit (DLAB). When set, access to the data transmit/receive register (THR/RBR) and the Interrupt Enable Register (IER) is disabled. Any access to these ports is now redirected to the Divisor Latch Registers. Setting this bit, loading the Divisor Registers, and clearing DLAB should be done with interrupts disabled. +
 Bit 6 -> Set Break. When set to "1", the transmitter begins to transmit continuous Spacing until this bit is set to "0". This overrides any bits of characters that are being transmitted. +
 Bit 5 -> Stick Parity. When parity is enabled, setting this bit causes parity to always be "1" or "0", based on the value of Bit 4.
 Bit 4 -> Even Parity Select (EPS). When parity is enabled and Bit 5 is "0", setting this bit causes even parity to be transmitted and expected. Otherwise, odd parity is used. +
 Bit 3 -> Parity Enable (PEN). When set to "1", a parity bit is inserted between the last bit of the data and the Stop Bit. The UART will also expect parity to be present in the received data. +
 Bit 2 -> Number of Stop Bits (STB). If set to "1" and using 5-bit data words, 1.5 Stop Bits are transmitted and expected in each data word. For 6, 7 and 8-bit data words, 2 Stop Bits are transmitted and expected. When this bit is set to "0", one Stop Bit is used on each data word. +
 Bit 1 -> Word Length Select Bit #1 (WLSB1) +
 Bit 0 -> Word Length Select Bit #0 (WLSB0) +
 Together these bits specify the number of bits in each data word. +
 1 0 Word Length +
 0 0 5 Data Bits +
 0 1 6 Data Bits +
 1 0 7 Data Bits +
 1 1 8 Data Bits +
 
 |+0x04
 |write/read
 |Modem Control Register (MCR) +
 Bit 7 -> Reserved, always 0. +
 Bit 6 -> Reserved, always 0. +
 Bit 5 -> Reserved, always 0. +
 Bit 4 -> Loop-Back Enable. When set to "1", the UART transmitter and receiver are internally connected together to allow diagnostic operations. In addition, the UART modem control outputs are connected to the UART modem control inputs. CTS is connected to RTS, DTR is connected to DSR, OUT1 is connected to RI, and OUT 2 is connected to DCD. +
 Bit 3 -> OUT 2. An auxiliary output that the host processor may set high or low. In the IBM PC serial adapter (and most clones), OUT 2 is used to tri-state (disable) the interrupt signal from the 8250/16450/16550 UART. +
 Bit 2 -> OUT 1. An auxiliary output that the host processor may set high or low. This output is not used on the IBM PC serial adapter. +
 Bit 1 -> Request to Send (RTS). When set to "1", the output of the UART -RTS line is Low (Active). +
 Bit 0 -> Data Terminal Ready (DTR). When set to "1", the output of the UART -DTR line is Low (Active). +
 
 |+0x05
 |write/read
 |Line Status Register (LSR) +
 Bit 7 -> Error in Receiver FIFO. On the 8250/16450 UART, this bit is zero. This bit is set to "1" when any of the bytes in the FIFO have one or more of the following error conditions: PE, FE, or BI. +
 Bit 6 -> Transmitter Empty (TEMT). When set to "1", there are no words remaining in the transmit FIFO or the transmit shift register. The transmitter is completely idle. +
 Bit 5 -> Transmitter Holding Register Empty (THRE). When set to "1", the FIFO (or holding register) now has room for at least one additional word to transmit. The transmitter may still be transmitting when this bit is set to "1". +
 Bit 4 -> Break Interrupt (BI). The receiver has detected a Break signal. +
 Bit 3 -> Framing Error (FE). A Start Bit was detected but the Stop Bit did not appear at the expected time. The received word is probably garbled. +
 Bit 2 -> Parity Error (PE). The parity bit was incorrect for the word received. +
 Bit 1 -> Overrun Error (OE). A new word was received and there was no room in the receive buffer. The newly-arrived word in the shift register is discarded. On 8250/16450 UARTs, the word in the holding register is discarded and the newly- arrived word is put in the holding register. +
 Bit 0 -> Data Ready (DR) One or more words are in the receive FIFO that the host may read. A word must be completely received and moved from the shift register into the FIFO (or holding register for 8250/16450 designs) before this bit is set.
 
 |+0x06
 |write/read
 |Modem Status Register (MSR) +
 Bit 7 -> Data Carrier Detect (DCD). Reflects the state of the DCD line on the UART. +
 Bit 6 -> Ring Indicator (RI). Reflects the state of the RI line on the UART. +
 Bit 5 -> Data Set Ready (DSR). Reflects the state of the DSR line on the UART. +
 Bit 4 -> Clear To Send (CTS). Reflects the state of the CTS line on the UART. +
 Bit 3 -> Delta Data Carrier Detect (DDCD). Set to "1" if the -DCD line has changed state one more time since the last time the MSR was read by the host. +
 Bit 2 -> Trailing Edge Ring Indicator (TERI). Set to "1" if the -RI line has had a low to high transition since the last time the MSR was read by the host. +
 Bit 1 -> Delta Data Set Ready (DDSR). Set to "1" if the -DSR line has changed state one more time since the last time the MSR was read by the host. +
 Bit 0 -> Delta Clear To Send (DCTS). Set to "1" if the -CTS line has changed state one more time since the last time the MSR was read by the host. +
 |+0x07
 |write/read
 |Scratch Register (SCR). This register performs no function in the UART. Any value can be written by the host to this location and read by the host later on.
 |===
 
 === Beyond the 16550A UART
 
 Although National Semiconductor has not offered any components compatible with the 16550 that provide additional features, various other vendors have. 
 Some of these components are described below.
 It should be understood that to effectively utilize these improvements, drivers may have to be provided by the chip vendor since most of the popular operating systems do not support features beyond those provided by the 16550.
 
 ST16650::
 By default this part is similar to the NS16550A, but an extended 32-byte send and receive buffer can be optionally enabled.
 Made by StarTech.
 
 TIL16660::
 By default this part behaves similar to the NS16550A, but an extended 64-byte send and receive buffer can be optionally enabled.
 Made by Texas Instruments.
 
 Hayes ESP::
 This proprietary plug-in card contains a 2048-byte send and receive buffer, and supports data rates to 230.4Kbit/sec.
 Made by Hayes.
 
 In addition to these "dumb" UARTs, many vendors produce intelligent serial communication boards.
 This type of design usually provides a microprocessor that interfaces with several UARTs, processes and buffers the data, and then alerts the main PC processor when necessary.
 As the UARTs are not directly accessed by the PC processor in this type of communication system, it is not necessary for the vendor to use UARTs that are compatible with the 8250, 16450, or the 16550 UART.
 This leaves the designer free to components that may have better performance characteristics.
 
 [[sio]]
 == Configuring the [.filename]#sio# driver
 
 The [.filename]#sio# driver provides support for NS8250-, NS16450-, NS16550 and NS16550A-based EIA RS-232C (CCITT V.24) communications interfaces. 
 Several multiport cards are supported as well.
 See the man:sio[4] manual page for detailed technical documentation.
 
 === Digi International (DigiBoard) PC/8
 
 _Contributed by `{awebster}`. 26 August 1995._
 
 Here is a config snippet from a machine with a Digi International PC/8 with 16550.
 It has 8 modems connected to these 8 lines, and they work just great.
 Do not forget to add `options COM_MULTIPORT` or it will not work very well!
 
 [.programlisting]
 ....
 device          sio4    at isa? port 0x100 flags 0xb05
 device          sio5    at isa? port 0x108 flags 0xb05
 device          sio6    at isa? port 0x110 flags 0xb05
 device          sio7    at isa? port 0x118 flags 0xb05
 device          sio8    at isa? port 0x120 flags 0xb05
 device          sio9    at isa? port 0x128 flags 0xb05
 device          sio10   at isa? port 0x130 flags 0xb05
 device          sio11   at isa? port 0x138 flags 0xb05 irq 9
 ....
 
 The trick in setting this up is that the MSB of the flags represent the last SIO port, in this case 11 so flags are 0xb05.
 
 === Boca 16
 
 _Contributed by `{whiteside}`. 26 August 1995._
 
 The procedures to make a Boca 16 port board with FreeBSD are pretty straightforward, but you will need a couple things to make it work:
 
 . You either need the kernel sources installed so you can recompile the necessary options or you will need someone else to compile it for you. The 2.0.5 default kernel does _not_ come with multiport support enabled and you will need to add a device entry for each port anyways.
 . Two, you will need to know the interrupt and IO setting for your Boca Board so you can set these options properly in the kernel.
 
 One important note - the actual UART chips for the Boca 16 are in the connector box, not on the internal board itself.
 So if you have it unplugged, probes of those ports will fail.
 I have never tested booting with the box unplugged and plugging it back in, and I suggest you do not either.
 
 If you do not already have a custom kernel configuration file set up, refer to link:{handbook}#kernelconfig[Kernel Configuration] chapter of the FreeBSD Handbook for general procedures.
 The following are the specifics for the Boca 16 board and assume you are using the kernel name MYKERNEL and editing with vi.
 
 [.procedure]
 ====
 . Add the line 
 +
 [.programlisting]
 ....
 options COM_MULTIPORT
 ....
 to the config file.
 . Where the current `device sio__n__` lines are, you will need to add 16 more devices. The following example is for a Boca Board with an interrupt of 3, and a base IO address 100h. The IO address for Each port is +8 hexadecimal from the previous port, thus the 100h, 108h, 110h... addresses.
 +
 [.programlisting]
 ....
 device sio1 at isa? port 0x100 flags 0x1005
 device sio2 at isa? port 0x108 flags 0x1005
 device sio3 at isa? port 0x110 flags 0x1005
 device sio4 at isa? port 0x118 flags 0x1005
 ...
 device sio15 at isa? port 0x170 flags 0x1005
 device sio16 at isa? port 0x178 flags 0x1005 irq 3
 ....
-+ 
++
 The flags entry _must_ be changed from this example unless you are using the exact same sio assignments.
 Flags are set according to 0x``__MYY__`` where _M_ indicates the minor number of the master port (the last port on a Boca 16) and _YY_ indicates if FIFO is enabled or disabled(enabled), IRQ sharing is used(yes) and if there is an AST/4 compatible IRQ control register(no).
 In this example, 
 +
 [.programlisting]
 ....
  flags
 	      0x1005
 ....
 indicates that the master port is sio16.
 If I added another board and assigned sio17 through sio28, the flags for all 16 ports on _that_ board would be 0x1C05, where 1C indicates the minor number of the master port.
 Do not change the 05 setting.
 . Save and complete the kernel configuration, recompile, install and reboot. Presuming you have successfully installed the recompiled kernel and have it set to the correct address and IRQ, your boot message should indicate the successful probe of the Boca ports as follows: (obviously the sio numbers, IO and IRQ could be different)
 +
 [source,shell]
 ....
 sio1 at 0x100-0x107 flags 0x1005 on isa
 sio1: type 16550A (multiport)
 sio2 at 0x108-0x10f flags 0x1005 on isa
 sio2: type 16550A (multiport)
 sio3 at 0x110-0x117 flags 0x1005 on isa
 sio3: type 16550A (multiport)
 sio4 at 0x118-0x11f flags 0x1005 on isa
 sio4: type 16550A (multiport)
 sio5 at 0x120-0x127 flags 0x1005 on isa
 sio5: type 16550A (multiport)
 sio6 at 0x128-0x12f flags 0x1005 on isa
 sio6: type 16550A (multiport)
 sio7 at 0x130-0x137 flags 0x1005 on isa
 sio7: type 16550A (multiport)
 sio8 at 0x138-0x13f flags 0x1005 on isa
 sio8: type 16550A (multiport)
 sio9 at 0x140-0x147 flags 0x1005 on isa
 sio9: type 16550A (multiport)
 sio10 at 0x148-0x14f flags 0x1005 on isa
 sio10: type 16550A (multiport)
 sio11 at 0x150-0x157 flags 0x1005 on isa
 sio11: type 16550A (multiport)
 sio12 at 0x158-0x15f flags 0x1005 on isa
 sio12: type 16550A (multiport)
 sio13 at 0x160-0x167 flags 0x1005 on isa
 sio13: type 16550A (multiport)
 sio14 at 0x168-0x16f flags 0x1005 on isa
 sio14: type 16550A (multiport)
 sio15 at 0x170-0x177 flags 0x1005 on isa
 sio15: type 16550A (multiport)
 sio16 at 0x178-0x17f irq 3 flags 0x1005 on isa
 sio16: type 16550A (multiport master)
 ....
-+ 
++
 If the messages go by too fast to see, 
 +
 [source,shell]
 ....
 # dmesg | more
 ....
 will show you the boot messages.
 . Next, appropriate entries in [.filename]#/dev# for the devices must be made using the [.filename]#/dev/MAKEDEV# script. This step can be omitted if you are running FreeBSD 5.X with a kernel that has man:devfs[5] support compiled in.
-+ 
++
 If you do need to create the [.filename]#/dev# entries, run the following as `root`:
 +
 [source,shell]
 ....
 # cd /dev
 # ./MAKEDEV tty1
 # ./MAKEDEV cua1
 
 (everything in between)
 # ./MAKEDEV ttyg
 # ./MAKEDEV cuag
 ....
-+ 
++
 If you do not want or need call-out devices for some reason, you can dispense with making the [.filename]#cua*# devices.
 . If you want a quick and sloppy way to make sure the devices are working, you can simply plug a modem into each port and (as root) 
 +
 [source,shell]
 ....
 # echo at > ttyd*
 ....
 for each device you have made. You _should_ see the RX lights flash for each working port.
 ====
 
 === Support for Cheap Multi-UART Cards
 
 _Contributed by Helge Oldach_ mailto:hmo@sep.hamburg.com[hmo@sep.hamburg.com], September 1999
 
 Ever wondered about FreeBSD support for your 20$ multi-I/O card with two (or more) COM ports, sharing IRQs? Here is how:
 
 Usually the only option to support these kind of boards is to use a distinct IRQ for each port.
 For example, if your CPU board has an on-board [.filename]#COM1# port (aka [.filename]#sio0#-I/O address 0x3F8 and IRQ 4) and you have an extension board with two UARTs, you will commonly need to configure them as [.filename]#COM2# (aka [.filename]#sio1#-I/O address 0x2F8 and IRQ 3), and the third port (aka [.filename]#sio2#) as I/O 0x3E8 and IRQ 5.
 Obviously this is a waste of IRQ resources, as it should be basically possible to run both extension board ports using a single IRQ with the `COM_MULTIPORT` configuration described in the previous sections.
 
 Such cheap I/O boards commonly have a 4 by 3 jumper matrix for the COM ports, similar to the following:
 
 [.programlisting]
 ....
             o  o  o  *
 Port A               |
             o  *  o  *
 Port B         |
             o  *  o  o
 IRQ         2  3  4  5
 ....
 
 Shown here is port A wired for IRQ 5 and port B wired for IRQ 3.
 The IRQ columns on your specific board may vary-other boards may supply jumpers for IRQs 3, 4, 5, and 7 instead.
 
 One could conclude that wiring both ports for IRQ 3 using a handcrafted wire-made jumper covering all three connection points in the IRQ 3 column would solve the issue, but no.
 You cannot duplicate IRQ 3 because the output drivers of each UART are wired in a "totem pole" fashion, so if one of the UARTs drives IRQ 3, the output signal will not be what you would expect.
 Depending on the implementation of the extension board or your motherboard, the IRQ 3 line will continuously stay up, or always stay low.
 
 You need to decouple the IRQ drivers for the two UARTs, so that the IRQ line of the board only goes up if (and only if) one of the UARTs asserts a IRQ, and stays low otherwise.
 The solution was proposed by Joerg Wunsch mailto:j@ida.interface-business.de[j@ida.interface-business.de]: To solder up a wired-or consisting of two diodes (Germanium or Schottky-types strongly preferred) and a 1 kOhm resistor.
 Here is the schematic, starting from the 4 by 3 jumper field above:
 
 [.programlisting]
 ....
                           Diode
                 +---------->|-------+
                /                    |
             o  *  o  o              |     1 kOhm
 Port A                              +----|######|-------+
             o  *  o  o              |                   |
 Port B          `-------------------+                 ==+==
             o  *  o  o              |                 Ground
                 \                   |
                  +--------->|-------+
 IRQ         2  3  4  5    Diode
 ....
 
 The cathodes of the diodes are connected to a common point, together with a 1 kOhm pull-down resistor.
 It is essential to connect the resistor to ground to avoid floating of the IRQ line on the bus.
 
 Now we are ready to configure a kernel.
 Staying with this example, we would configure:
 
 [.programlisting]
 ....
 # standard on-board COM1 port
 device          sio0    at isa? port "IO_COM1" flags 0x10
 # patched-up multi-I/O extension board
 options         COM_MULTIPORT
 device          sio1    at isa? port "IO_COM2" flags 0x205
 device          sio2    at isa? port "IO_COM3" flags 0x205 irq 3
 ....
 
 Note that the `flags` setting for [.filename]#sio1# and [.filename]#sio2# is truly essential; refer to man:sio[4] for details.
 (Generally, the `2` in the "flags" attribute refers to [.filename]#sio#`2` which holds the IRQ, and you surely want a `5` low nibble.)
 With kernel verbose mode turned on this should yield something similar to this:
 
 [source,shell]
 ....
 sio0: irq maps: 0x1 0x11 0x1 0x1
 sio0 at 0x3f8-0x3ff irq 4 flags 0x10 on isa
 sio0: type 16550A
 sio1: irq maps: 0x1 0x9 0x1 0x1
 sio1 at 0x2f8-0x2ff flags 0x205 on isa
 sio1: type 16550A (multiport)
 sio2: irq maps: 0x1 0x9 0x1 0x1
 sio2 at 0x3e8-0x3ef irq 3 flags 0x205 on isa
 sio2: type 16550A (multiport master)
 ....
 
 Though [.filename]#/sys/i386/isa/sio.c# is somewhat cryptic with its use of the "irq maps" array above, the basic idea is that you observe `0x1` in the first, third, and fourth place.
 This means that the corresponding IRQ was set upon output and cleared after, which is just what we would expect.
 If your kernel does not display this behavior, most likely there is something wrong with your wiring.
 
 [[cy]]
 == Configuring the [.filename]#cy# driver
 
 _Contributed by Alex Nash. 6 June 1996._
 
 The Cyclades multiport cards are based on the [.filename]#cy# driver instead of the usual [.filename]#sio# driver used by other multiport cards.
 Configuration is a simple matter of:
 
 [.procedure]
 ====
 . Add the [.filename]#cy# device to your kernel configuration (note that your irq and iomem settings may differ).
 +
 [.programlisting]
 ....
 device cy0 at isa? irq 10 iomem 0xd4000 iosiz 0x2000
 ....
 . Rebuild and install the new kernel.
 . Make the device nodes by typing (the following example assumes an 8-port board):
 +
 [source,shell]
 ....
 # cd /dev
 # for i in 0 1 2 3 4 5 6 7;do ./MAKEDEV cuac$i ttyc$i;done
 ....
 
 . If appropriate, add dialup entries to [.filename]#/etc/ttys# by duplicating serial device (`ttyd`) entries and using `ttyc` in place of `ttyd`. For example:
 +
 [.programlisting]
 ....
 ttyc0   "/usr/libexec/getty std.38400"  unknown on insecure
 ttyc1   "/usr/libexec/getty std.38400"  unknown on insecure
 ttyc2   "/usr/libexec/getty std.38400"  unknown on insecure
 ...
 ttyc7   "/usr/libexec/getty std.38400"  unknown on insecure
 ....
 . Reboot with the new kernel.
 ====
 
 == Configuring the [.filename]#si# driver
 
 _Contributed by `{nsayer}`. 25 March 1998._
 
 The Specialix SI/XIO and SX multiport cards use the [.filename]#si# driver.
 A single machine can have up to 4 host cards.
 The following host cards are supported:
 
 * ISA SI/XIO host card (2 versions)
 * EISA SI/XIO host card
 * PCI SI/XIO host card
 * ISA SX host card
 * PCI SX host card
 
 Although the SX and SI/XIO host cards look markedly different, their functionality are basically the same.
 The host cards do not use I/O locations, but instead require a 32K chunk of memory.
 The factory configuration for ISA cards places this at `0xd0000-0xd7fff`.
 They also require an IRQ.
 PCI cards will, of course, auto-configure themselves.
 
 You can attach up to 4 external modules to each host card.
 The external modules contain either 4 or 8 serial ports.
 They come in the following varieties:
 
 * SI 4 or 8 port modules. Up to 57600 bps on each port supported.
 * XIO 8 port modules. Up to 115200 bps on each port supported. One type of XIO module has 7 serial and 1 parallel port.
 * SXDC 8 port modules. Up to 921600 bps on each port supported. Like XIO, a module is available with one parallel port as well.
 
 To configure an ISA host card, add the following line to your kernel configuration file, changing the numbers as appropriate:
 
 [.programlisting]
 ....
 device si0 at isa? iomem 0xd0000 irq 11
 ....
 
 Valid IRQ numbers are 9, 10, 11, 12 and 15 for SX ISA host cards and 11, 12 and 15 for SI/XIO ISA host cards.
 
 To configure an EISA or PCI host card, use this line:
 
 [.programlisting]
 ....
 device si0
 ....
 
 After adding the configuration entry, rebuild and install your new kernel.
 
 [NOTE]
 ====
 The following step, is not necessary if you are using man:devfs[5] in FreeBSD 5._X_.
 ====
 
 After rebooting with the new kernel, you need to make the device nodes in [.filename]#/dev#.
 The [.filename]#MAKEDEV# script will take care of this for you.
 Count how many total ports you have and type:
 
 [source,shell]
 ....
 # cd /dev
 # ./MAKEDEV ttyAnn cuaAnn
 ....
 
 (where _nn_ is the number of ports)
 
 If you want login prompts to appear on these ports, you will need to add lines like this to [.filename]#/etc/ttys#:
 
 [.programlisting]
 ....
 ttyA01  "/usr/libexec/getty std.9600"   vt100   on insecure
 ....
 
 Change the terminal type as appropriate.
 For modems, `dialup` or `unknown` is fine.
diff --git a/documentation/content/en/articles/solid-state/_index.adoc b/documentation/content/en/articles/solid-state/_index.adoc
index 0ae410fcdf..ca2ddad07e 100644
--- a/documentation/content/en/articles/solid-state/_index.adoc
+++ b/documentation/content/en/articles/solid-state/_index.adoc
@@ -1,305 +1,305 @@
 ---
 title: FreeBSD and Solid State Devices
 authors:
   - author: John Kozubik
     email: john@kozubik.com
 copyright: 2001 - 2021 The FreeBSD Documentation Project
 description: The use of solid state disk devices in FreeBSD
 trademarks: ["freebsd", "general"]
 tags: ["Solid State", "embedded", "FreeBSD"]
 ---
 
 = FreeBSD and Solid State Devices
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 [.abstract-title]
 Abstract
 
 This article covers the use of solid state disk devices in FreeBSD to create embedded systems.
 
 Embedded systems have the advantage of increased stability due to the lack of integral moving parts (hard drives).
 Account must be taken, however, for the generally low disk space available in the system and the durability of the storage medium.
 
 Specific topics to be covered include the types and attributes of solid state media suitable for disk use in FreeBSD, kernel options that are of interest in such an environment, the [.filename]#rc.initdiskless# mechanisms that automate the initialization of such systems and the need for read-only filesystems, and building filesystems from scratch.
 The article will conclude with some general strategies for small and read-only FreeBSD environments.
 
 '''
 
 toc::[]
 
 [[intro]]
 == Solid State Disk Devices
 
 The scope of this article will be limited to solid state disk devices made from flash memory.
 Flash memory is a solid state memory (no moving parts) that is non-volatile (the memory maintains data even after all power sources have been disconnected).
 Flash memory can withstand tremendous physical shock and is reasonably fast (the flash memory solutions covered in this article are slightly slower than a EIDE hard disk for write operations, and much faster for read operations).
 One very important aspect of flash memory, the ramifications of which will be discussed later in this article, is that each sector has a limited rewrite capacity.
 You can only write, erase, and write again to a sector of flash memory a certain number of times before the sector becomes permanently unusable.
 Although many flash memory products automatically map bad blocks, and although some even distribute write operations evenly throughout the unit, the fact remains that there exists a limit to the amount of writing that can be done to the device.
 Competitive units have between 1,000,000 and 10,000,000 writes per sector in their specification.
 This figure varies due to the temperature of the environment.
 
 Specifically, we will be discussing ATA compatible compact-flash units, which are quite popular as storage media for digital cameras.
 Of particular interest is the fact that they pin out directly to the IDE bus and are compatible with the ATA command set.
 Therefore, with a very simple and low-cost adaptor, these devices can be attached directly to an IDE bus in a computer.
 Once implemented in this manner, operating systems such as FreeBSD see the device as a normal hard disk (albeit small).
 
 Other solid state disk solutions do exist, but their expense, obscurity, and relative unease of use places them beyond the scope of this article.
 
 [[kernel]]
 == Kernel Options
 
 A few kernel options are of specific interest to those creating an embedded FreeBSD system.
 
 All embedded FreeBSD systems that use flash memory as system disk will be interested in memory disks and memory filesystems.
 As a result of the limited number of writes that can be done to flash memory, the disk and the filesystems on the disk will most likely be mounted read-only. 
 In this environment, filesystems such as [.filename]#/tmp# and [.filename]#/var# are mounted as memory filesystems to allow the system to create logs and update counters and temporary files.
 Memory filesystems are a critical component to a successful solid state FreeBSD implementation.
 
 You should make sure the following lines exist in your kernel configuration file:
 
 [.programlisting]
 ....
 options         MFS             # Memory Filesystem
 options         MD_ROOT         # md device usable as a potential root device
 pseudo-device   md              # memory disk
 ....
 
 [[ro-fs]]
 == The `rc` Subsystem and Read-Only Filesystems
 
 The post-boot initialization of an embedded FreeBSD system is controlled by [.filename]#/etc/rc.initdiskless#.
 
 [.filename]#/etc/rc.d/var# mounts [.filename]#/var# as a memory filesystem, makes a configurable list of directories in [.filename]#/var# with the man:mkdir[1] command, and changes modes on some of those directories.
 In the execution of [.filename]#/etc/rc.d/var#, one other [.filename]#rc.conf# variable comes into play - `varsize`.
 A [.filename]#/var# partition is created by [.filename]#/etc/rc.d/var# based on the value of this variable in [.filename]#rc.conf#:
 
 [.programlisting]
 ....
 varsize=8192
 ....
 
 Remember that this value is in sectors by default.
 
 The fact that [.filename]#/var# is a read-write filesystem is an important distinction, as the [.filename]#/# partition (and any other partitions you may have on your flash media) should be mounted read-only.
 Remember that in <<intro>> we detailed the limitations of flash memory - specifically the limited write capability.
 The importance of not mounting filesystems on flash media read-write, and the importance of not using a swap file, cannot be overstated.
 A swap file on a busy system can burn through a piece of flash media in less than one year.
 Heavy logging or temporary file creation and destruction can do the same.
 Therefore, in addition to removing the `swap` entry from your [.filename]#/etc/fstab#, you should also change the Options field for each filesystem to `ro` as follows:
 
 [.programlisting]
 ....
 # Device                Mountpoint      FStype  Options         Dump    Pass#
 /dev/ad0s1a             /               ufs     ro              1       1
 ....
 
 A few applications in the average system will immediately begin to fail as a result of this change.
 For instance, cron will not run properly as a result of missing cron tabs in the [.filename]#/var# created by [.filename]#/etc/rc.d/var#, and syslog and dhcp will encounter problems as well as a result of the read-only filesystem and missing items in the [.filename]#/var# that [.filename]#/etc/rc.d/var# has created.
 These are only temporary problems though, and are addressed, along with solutions to the execution of other common software packages in <<strategies>>.
 
 An important thing to remember is that a filesystem that was mounted read-only with [.filename]#/etc/fstab# can be made read-write at any time by issuing the command:
 
 [source,shell]
 ....
 # /sbin/mount -uw partition
 ....
 
 and can be toggled back to read-only with the command:
 
 [source,shell]
 ....
 # /sbin/mount -ur partition
 ....
 
 == Building a File System from Scratch
 
 Since ATA compatible compact-flash cards are seen by FreeBSD as normal IDE hard drives, you could theoretically install FreeBSD from the network using the kern and mfsroot floppies or from a CD.
 
 However, even a small installation of FreeBSD using normal installation procedures can produce a system in size of greater than 200 megabytes.
 Most people will be using smaller flash memory devices (128 megabytes is considered fairly large - 32 or even 16 megabytes is common), so an installation using normal mechanisms is not possible-there is simply not enough disk space for even the smallest of conventional installations.
 
 The easiest way to overcome this space limitation is to install FreeBSD using conventional means to a normal hard disk.
 After the installation is complete, pare down the operating system to a size that will fit onto your flash media, then tar the entire filesystem.
 The following steps will guide you through the process of preparing a piece of flash memory for your tarred filesystem.
 Remember, because a normal installation is not being performed, operations such as partitioning, labeling, file-system creation, etc. need to be performed by hand.
 In addition to the kern and mfsroot floppy disks, you will also need to use the fixit floppy.
 
 [.procedure]
 ====
 . Partitioning Your Flash Media Device
-+ 
++
 After booting with the kern and mfsroot floppies, choose `custom` from the installation menu.
 In the custom installation menu, choose `partition`.
 In the partition menu, you should delete all existing partitions using kbd:[d].
 After deleting all existing partitions, create a partition using kbd:[c] and accept the default value for the size of the partition.
 When asked for the type of the partition, make sure the value is set to `165`.
 Now write this partition table to the disk by pressing kbd:[w] (this is a hidden option on this screen).
 If you are using an ATA compatible compact flash card, you should choose the FreeBSD Boot Manager.
 Now press kbd:[q] to quit the partition menu.
 You will be shown the boot manager menu once more - repeat the choice you made earlier.
 . Creating Filesystems on Your Flash Memory Device
-+ 
++
 Exit the custom installation menu, and from the main installation menu choose the `fixit` option.
 After entering the fixit environment, enter the following command:
 +
 [source,shell]
 ....
 # disklabel -e /dev/ad0c
 ....
-+ 
++
 At this point you will have entered the vi editor under the auspices of the disklabel command.
 Next, you need to add an `a:` line at the end of the file. This `a:` line should look like:
 +
 [.programlisting]
 ....
 a:      123456  0       4.2BSD  0       0
 ....
-+ 
++
 Where _123456_ is a number that is exactly the same as the number in the existing `c:` entry for size.
 Basically you are duplicating the existing `c:` line as an `a:` line, making sure that fstype is `4.2BSD`.
 Save the file and exit.
 +
 [source,shell]
 ....
 # disklabel -B -r /dev/ad0c
 # newfs /dev/ad0a
 ....
 
 . Placing Your Filesystem on the Flash Media
-+ 
++
 Mount the newly prepared flash media:
 +
 [source,shell]
 ....
 # mount /dev/ad0a /flash
 ....
-+ 
++
 Bring this machine up on the network so we may transfer our tar file and explode it onto our flash media filesystem.
 One example of how to do this is:
 +
 [source,shell]
 ....
 # ifconfig xl0 192.168.0.10 netmask 255.255.255.0
 # route add default 192.168.0.1
 ....
-+ 
++
 Now that the machine is on the network, transfer your tar file.
 You may be faced with a bit of a dilemma at this point - if your flash memory part is 128 megabytes, for instance, and your tar file is larger than 64 megabytes, you cannot have your tar file on the flash media at the same time as you explode it - you will run out of space.
 One solution to this problem, if you are using FTP, is to untar the file while it is transferred over FTP.
 If you perform your transfer in this manner, you will never have the tar file and the tar contents on your disk at the same time:
 +
 [source,shell]
 ....
 ftp> get tarfile.tar "| tar xvf -"
 ....
-+ 
++
 If your tarfile is gzipped, you can accomplish this as well:
 +
 [source,shell]
 ....
 ftp> get tarfile.tar "| zcat | tar xvf -"
 ....
-+ 
++
 After the contents of your tarred filesystem are on your flash memory filesystem, you can unmount the flash memory and reboot:
 +
 [source,shell]
 ....
 # cd /
 # umount /flash
 # exit
 ....
-+ 
++
 Assuming that you configured your filesystem correctly when it was built on the normal hard disk (with your filesystems mounted read-only, and with the necessary options compiled into the kernel) you should now be successfully booting your FreeBSD embedded system.
 ====
 
 [[strategies]]
 == System Strategies for Small and Read Only Environments
 
 In <<ro-fs>>, it was pointed out that the [.filename]#/var# filesystem constructed by [.filename]#/etc/rc.d/var# and the presence of a read-only root filesystem causes problems with many common software packages used with FreeBSD.
 In this article, suggestions for successfully running cron, syslog, ports installations, and the Apache web server will be provided.
 
 === Cron
 
 Upon boot, [.filename]#/var# gets populated by [.filename]#/etc/rc.d/var# using the list from [.filename]#/etc/mtree/BSD.var.dist#, so the [.filename]#cron#, [.filename]#cron/tabs#, [.filename]#at#, and a few other standard directories get created.
 
 However, this does not solve the problem of maintaining cron tabs across reboots.
 When the system reboots, the [.filename]#/var# filesystem that is in memory will disappear and any cron tabs you may have had in it will also disappear. 
 Therefore, one solution would be to create cron tabs for the users that need them, mount your [.filename]#/# filesystem as read-write and copy those cron tabs to somewhere safe, like [.filename]#/etc/tabs#, then add a line to the end of [.filename]#/etc/rc.initdiskless# that copies those crontabs into [.filename]#/var/cron/tabs# after that directory has been created during system initialization.
 You may also need to add a line that changes modes and permissions on the directories you create and the files you copy with [.filename]#/etc/rc.initdiskless#.
 
 === Syslog
 
 [.filename]#syslog.conf# specifies the locations of certain log files that exist in [.filename]#/var/log#.
 These files are not created by [.filename]#/etc/rc.d/var# upon system initialization.
 Therefore, somewhere in [.filename]#/etc/rc.d/var#, after the section that creates the directories in [.filename]#/var#, you will need to add something like this:
 
 [source,shell]
 ....
 # touch /var/log/security /var/log/maillog /var/log/cron /var/log/messages
 # chmod 0644 /var/log/*
 ....
 
 === Ports Installation
 
 Before discussing the changes necessary to successfully use the ports tree, a reminder is necessary regarding the read-only nature of your filesystems on the flash media.
 Since they are read-only, you will need to temporarily mount them read-write using the mount syntax shown in <<ro-fs>>.
 You should always remount those filesystems read-only when you are done with any maintenance - unnecessary writes to the flash media could considerably shorten its lifespan.
 
 To make it possible to enter a ports directory and successfully run `make install`, we must create a packages directory on a non-memory filesystem that will keep track of our packages across reboots.
 As it is necessary to mount your filesystems as read-write for the installation of a package anyway, it is sensible to assume that an area on the flash media can also be used for package information to be written to.
 
 First, create a package database directory.
 This is normally in [.filename]#/var/db/pkg#, but we cannot place it there as it will disappear every time the system is booted.
 
 [source,shell]
 ....
 # mkdir /etc/pkg
 ....
 
 Now, add a line to [.filename]#/etc/rc.d/var# that links the [.filename]#/etc/pkg# directory to [.filename]#/var/db/pkg#. An example:
 
 [source,shell]
 ....
 # ln -s /etc/pkg /var/db/pkg
 ....
 
 Now, any time that you mount your filesystems as read-write and install a package, the `make install` will work, and package information will be written successfully to [.filename]#/etc/pkg# (because the filesystem will, at that time, be mounted read-write) which will always be available to the operating system as [.filename]#/var/db/pkg#.
 
 === Apache Web Server
 
 [NOTE]
 ====
 The steps in this section are only necessary if Apache is set up to write its pid or log information outside of [.filename]#/var#.
 By default, Apache keeps its pid file in [.filename]#/var/run/httpd.pid# and its log files in [.filename]#/var/log#.
 ====
 
 It is now assumed that Apache keeps its log files in a directory [.filename]#apache_log_dir# outside of [.filename]#/var#.
 When this directory lives on a read-only filesystem, Apache will not be able to save any log files, and may have problems working.
 If so, it is necessary to add a new directory to the list of directories in [.filename]#/etc/rc.d/var# to create in [.filename]#/var#, and to link [.filename]#apache_log_dir# to [.filename]#/var/log/apache#.
 It is also necessary to set permissions and ownership on this new directory.
 
 First, add the directory `log/apache` to the list of directories to be created in [.filename]#/etc/rc.d/var#.
 
 Second, add these commands to [.filename]#/etc/rc.d/var# after the directory creation section:
 
 [source,shell]
 ....
 # chmod 0774 /var/log/apache
 # chown nobody:nobody /var/log/apache
 ....
 
 Finally, remove the existing [.filename]#apache_log_dir# directory, and replace it with a link:
 
 [source,shell]
 ....
 # rm -rf apache_log_dir
 # ln -s /var/log/apache apache_log_dir
 ....
diff --git a/documentation/content/en/articles/vinum/_index.adoc b/documentation/content/en/articles/vinum/_index.adoc
index 6b2db7cf8f..3fc70ed9b4 100644
--- a/documentation/content/en/articles/vinum/_index.adoc
+++ b/documentation/content/en/articles/vinum/_index.adoc
@@ -1,700 +1,700 @@
 ---
 title: The vinum Volume Manager
 authors:
   - author: Greg Lehey
 description: The vinum Volume Manager in FreeBSD
 tags: ["vinum", "Volume Manager", "FreeBSD"]
 ---
 
 = The vinum Volume Manager
 :doctype: article
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 
 
 ifeval::["{backend}" == "html5"]
 include::shared/en/urls.adoc[]
 :imagesdir: ../../../images/articles/vinum/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 include::../../../../shared/en/urls.adoc[]
 :imagesdir: ../../../../static/images/articles/vinum/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/articles/vinum/
 endif::[]
 
 '''
 
 toc::[]
 
 [[vinum-synopsis]]
 == Synopsis
 
 No matter the type of disks, there are always potential problems.
 The disks can be too small, too slow, or too unreliable to meet the system's requirements.
 While disks are getting bigger, so are data storage requirements.
 Often a file system is needed that is bigger than a disk's capacity.
 Various solutions to these problems have been proposed and implemented.
 
 One method is through the use of multiple, and sometimes redundant, disks.
 In addition to supporting various cards and controllers for hardware Redundant Array of Independent Disks RAID systems, the base FreeBSD system includes the [.filename]#vinum# volume manager, a block device driver that implements virtual disk drives and addresses these three problems.
 [.filename]#vinum# provides more flexibility, performance, and reliability than traditional disk storage and implements `RAID`-0, `RAID`-1, and `RAID`-5 models, both individually and in combination.
 
 This chapter provides an overview of potential problems with traditional disk storage, and an introduction to the [.filename]#vinum# volume manager.
 
 [NOTE]
 ====
 Starting with FreeBSD 5, [.filename]#vinum# has been rewritten in order to fit into the link:{handbook}#geom[GEOM architecture], while retaining the original ideas, terminology, and on-disk metadata.
 This rewrite is called _gvinum_ (for _GEOM vinum_).
 While this chapter uses the term [.filename]#vinum#, any command invocations should be performed with `gvinum`.
 The name of the kernel module has changed from the original [.filename]#vinum.ko# to [.filename]#geom_vinum.ko#, and all device nodes reside under [.filename]#/dev/gvinum# instead of [.filename]#/dev/vinum#.
 As of FreeBSD 6, the original [.filename]#vinum# implementation is no longer available in the code base.
 ====
 
 [[vinum-access-bottlenecks]]
 == Access Bottlenecks
 
 Modern systems frequently need to access data in a highly concurrent manner.
 For example, large FTP or HTTP servers can maintain thousands of concurrent sessions and have multiple 100 Mbit/s connections to the outside world, well beyond the sustained transfer rate of most disks.
 
 Current disk drives can transfer data sequentially at up to 70 MB/s, but this value is of little importance in an environment where many independent processes access a drive, and where they may achieve only a fraction of these values.
 In such cases, it is more interesting to view the problem from the viewpoint of the disk subsystem.
 The important parameter is the load that a transfer places on the subsystem, or the time for which a transfer occupies the drives involved in the transfer.
 
 In any disk transfer, the drive must first position the heads, wait for the first sector to pass under the read head, and then perform the transfer.
 These actions can be considered to be atomic as it does not make any sense to interrupt them.
 
 [[vinum-latency]] Consider a typical transfer of about 10 kB: the current generation of high-performance disks can position the heads in an average of 3.5 ms.
 The fastest drives spin at 15,000 rpm, so the average rotational latency (half a revolution) is 2 ms.
 At 70 MB/s, the transfer itself takes about 150 μs, almost nothing compared to the positioning time.
 In such a case, the effective transfer rate drops to a little over 1 MB/s and is clearly highly dependent on the transfer size.
 
 The traditional and obvious solution to this bottleneck is "more spindles": rather than using one large disk, use several smaller disks with the same aggregate storage space.
 Each disk is capable of positioning and transferring independently, so the effective throughput increases by a factor close to the number of disks used.
 
 The actual throughput improvement is smaller than the number of disks involved.
 Although each drive is capable of transferring in parallel, there is no way to ensure that the requests are evenly distributed across the drives.
 Inevitably the load on one drive will be higher than on another.
 
 The evenness of the load on the disks is strongly dependent on the way the data is shared across the drives.
 In the following discussion, it is convenient to think of the disk storage as a large number of data sectors which are addressable by number, rather like the pages in a book.
 The most obvious method is to divide the virtual disk into groups of consecutive sectors the size of the individual physical disks and store them in this manner, rather like taking a large book and tearing it into smaller sections.
 This method is called _concatenation_ and has the advantage that the disks are not required to have any specific size relationships.
 It works well when the access to the virtual disk is spread evenly about its address space.
 When access is concentrated on a smaller area, the improvement is less marked.
 <<vinum-concat, Concatenated Organization>> illustrates the sequence in which storage units are allocated in a concatenated organization.
 
 [[vinum-concat]]
 .Concatenated Organization
 image::vinum-concat.png[]
 
 An alternative mapping is to divide the address space into smaller, equal-sized components and store them sequentially on different devices.
 For example, the first 256 sectors may be stored on the first disk, the next 256 sectors on the next disk and so on.
 After filling the last disk, the process repeats until the disks are full.
 This mapping is called _striping_ or RAID-0.
 
 `RAID` offers various forms of fault tolerance, though RAID-0 is somewhat misleading as it provides no redundancy.
 Striping requires somewhat more effort to locate the data, and it can cause additional I/O load where a transfer is spread over multiple disks, but it can also provide a more constant load across the disks.
 <<vinum-striped, Striped Organization>> illustrates the sequence in which storage units are allocated in a striped organization.
 
 [[vinum-striped]]
 .Striped Organization
 image::vinum-striped.png[]
 
 [[vinum-data-integrity]]
 == Data Integrity
 
 The final problem with disks is that they are unreliable.
 Although reliability has increased tremendously over the last few years, disk drives are still the most likely core component of a server to fail.
 When they do, the results can be catastrophic and replacing a failed disk drive and restoring data can result in server downtime.
 
 One approach to this problem is _mirroring_, or `RAID-1`, which keeps two copies of the data on different physical hardware.
 Any write to the volume writes to both disks; a read can be satisfied from either, so if one drive fails, the data is still available on the other drive.
 
 Mirroring has two problems:
 
 * It requires twice as much disk storage as a non-redundant solution.
 * Writes must be performed to both drives, so they take up twice the bandwidth of a non-mirrored volume. Reads do not suffer from a performance penalty and can even be faster.
 
 An alternative solution is _parity_, implemented in `RAID` levels 2, 3, 4 and 5.
 Of these, `RAID-5` is the most interesting.
 As implemented in [.filename]#vinum#, it is a variant on a striped organization which dedicates one block of each stripe to parity one of the other blocks.
 As implemented by [.filename]#vinum#, a `RAID-5` plex is similar to a striped plex, except that it implements `RAID-5` by including a parity block in each stripe.
 As required by `RAID-5`, the location of this parity block changes from one stripe to the next.
 The numbers in the data blocks indicate the relative block numbers.
 
 [[vinum-raid5-org]]
 .`RAID`-5 Organization
 image::vinum-raid5-org.png[]
 
 Compared to mirroring, `RAID-5` has the advantage of requiring significantly less storage space.
 Read access is similar to that of striped organizations, but write access is significantly slower, approximately 25% of the read performance.
 If one drive fails, the array can continue to operate in degraded mode where a read from one of the remaining accessible drives continues normally, but a read from the failed drive is recalculated from the corresponding block from all the remaining drives.
 
 [[vinum-objects]]
 == [.filename]#vinum# Objects
 
 In order to address these problems, [.filename]#vinum# implements a four-level hierarchy of objects:
 
 * The most visible object is the virtual disk, called a _volume_. Volumes have essentially the same properties as a UNIX(R) disk drive, though there are some minor differences. For one, they have no size limitations.
 * Volumes are composed of _plexes_, each of which represent the total address space of a volume. This level in the hierarchy provides redundancy. Think of plexes as individual disks in a mirrored array, each containing the same data.
 * Since [.filename]#vinum# exists within the UNIX(R) disk storage framework, it would be possible to use UNIX(R) partitions as the building block for multi-disk plexes. In fact, this turns out to be too inflexible as UNIX(R) disks can have only a limited number of partitions. Instead, [.filename]#vinum# subdivides a single UNIX(R) partition, the _drive_, into contiguous areas called _subdisks_, which are used as building blocks for plexes.
 * Subdisks reside on [.filename]#vinum#_drives_, currently UNIX(R) partitions. [.filename]#vinum# drives can contain any number of subdisks. With the exception of a small area at the beginning of the drive, which is used for storing configuration and state information, the entire drive is available for data storage.
 
 The following sections describe the way these objects provide the functionality required of [.filename]#vinum#.
 
 === Volume Size Considerations
 
 Plexes can include multiple subdisks spread over all drives in the [.filename]#vinum# configuration.
 As a result, the size of an individual drive does not limit the size of a plex or a volume.
 
 === Redundant Data Storage
 
 [.filename]#vinum# implements mirroring by attaching multiple plexes to a volume.
 Each plex is a representation of the data in a volume.
 A volume may contain between one and eight plexes.
 
 Although a plex represents the complete data of a volume, it is possible for parts of the representation to be physically missing, either by design (by not defining a subdisk for parts of the plex) or by accident (as a result of the failure of a drive).
 As long as at least one plex can provide the data for the complete address range of the volume, the volume is fully functional.
 
 === Which Plex Organization?
 
 [.filename]#vinum# implements both concatenation and striping at the plex level:
 
 * A _concatenated plex_ uses the address space of each subdisk in turn. Concatenated plexes are the most flexible as they can contain any number of subdisks, and the subdisks may be of different length. The plex may be extended by adding additional subdisks. They require less CPU time than striped plexes, though the difference in CPU overhead is not measurable. On the other hand, they are most susceptible to hot spots, where one disk is very active and others are idle.
 * A _striped plex_ stripes the data across each subdisk. The subdisks must all be the same size and there must be at least two subdisks in order to distinguish it from a concatenated plex. The greatest advantage of striped plexes is that they reduce hot spots. By choosing an optimum sized stripe, about 256 kB, the load can be evened out on the component drives. Extending a plex by adding new subdisks is so complicated that [.filename]#vinum# does not implement it.
 
 <<vinum-comparison, [.filename]#vinum# Plex Organizations>> summarizes the advantages and disadvantages of each plex organization.
 
 [[vinum-comparison]]
 .[.filename]#vinum# Plex Organizations
 [cols="1,1,1,1,1", frame="none", options="header"]
 |===
 | Plex type
 | Minimum subdisks
 | Can add subdisks
 | Must be equal size
 | Application
 
 |concatenated
 |1
 |yes
 |no
 |Large data storage with maximum placement flexibility and moderate performance
 
 |striped
 |2
 |no
 |yes
 |High performance in combination with highly concurrent access
 |===
 
 [[vinum-examples]]
 == Some Examples
 
 [.filename]#vinum# maintains a _configuration database_ which describes the objects known to an individual system.
 Initially, the user creates the configuration database from one or more configuration files using man:gvinum[8].
 [.filename]#vinum# stores a copy of its configuration database on each disk _device_ under its control.
 This database is updated on each state change, so that a restart accurately restores the state of each [.filename]#vinum# object.
 
 === The Configuration File
 
 The configuration file describes individual [.filename]#vinum# objects.
 The definition of a simple volume might be:
 
 [.programlisting]
 ....
     drive a device /dev/da3h
     volume myvol
       plex org concat
         sd length 512m drive a
 ....
 
 This file describes four [.filename]#vinum# objects:
 
 * The _drive_ line describes a disk partition (_drive_) and its location relative to the underlying hardware. It is given the symbolic name _a_. This separation of symbolic names from device names allows disks to be moved from one location to another without confusion.
 * The _volume_ line describes a volume. The only required attribute is the name, in this case _myvol_.
 * The _plex_ line defines a plex. The only required parameter is the organization, in this case _concat_. No name is necessary as the system automatically generates a name from the volume name by adding the suffix _.px_, where _x_ is the number of the plex in the volume. Thus this plex will be called _myvol.p0_.
 * The _sd_ line describes a subdisk. The minimum specifications are the name of a drive on which to store it, and the length of the subdisk. No name is necessary as the system automatically assigns names derived from the plex name by adding the suffix _.sx_, where _x_ is the number of the subdisk in the plex. Thus [.filename]#vinum# gives this subdisk the name _myvol.p0.s0_.
 
 After processing this file, man:gvinum[8] produces the following output:
 
 [.programlisting]
 ....
 
 #  gvinum -> create config1
 Configuration summary
 Drives:         1 (4 configured)
 Volumes:        1 (4 configured)
 Plexes:         1 (8 configured)
 Subdisks:       1 (16 configured)
 
   D a                     State: up       Device /dev/da3h      Avail: 2061/2573 MB (80%)
 
   V myvol                 State: up       Plexes:       1 Size:      512 MB
 
   P myvol.p0            C State: up       Subdisks:     1 Size:      512 MB
 
   S myvol.p0.s0           State: up       PO:        0  B Size:      512 MB
 ....
 
 This output shows the brief listing format of man:gvinum[8].
 It is represented graphically in <<vinum-simple-vol, A Simple [.filename]#vinum# Volume>>.
 
 [[vinum-simple-vol]]
 .A Simple [.filename]#vinum# Volume
 image::vinum-simple-vol.png[]
 
 This figure, and the ones which follow, represent a volume, which contains the plexes, which in turn contains the subdisks.
 In this example, the volume contains one plex, and the plex contains one subdisk.
 
 This particular volume has no specific advantage over a conventional disk partition.
 It contains a single plex, so it is not redundant.
 The plex contains a single subdisk, so there is no difference in storage allocation from a conventional disk partition.
 The following sections illustrate various more interesting configuration methods.
 
 === Increased Resilience: Mirroring
 
 The resilience of a volume can be increased by mirroring.
 When laying out a mirrored volume, it is important to ensure that the subdisks of each plex are on different drives, so that a drive failure will not take down both plexes.
 The following configuration mirrors a volume:
 
 [.programlisting]
 ....
 	drive b device /dev/da4h
 	volume mirror
       plex org concat
         sd length 512m drive a
 	  plex org concat
 	    sd length 512m drive b
 ....
 
 In this example, it was not necessary to specify a definition of drive _a_ again, since [.filename]#vinum# keeps track of all objects in its configuration database.
 After processing this definition, the configuration looks like:
 
 [.programlisting]
 ....
 
 	Drives:         2 (4 configured)
 	Volumes:        2 (4 configured)
 	Plexes:         3 (8 configured)
 	Subdisks:       3 (16 configured)
 
 	D a                     State: up       Device /dev/da3h       Avail: 1549/2573 MB (60%)
 	D b                     State: up       Device /dev/da4h       Avail: 2061/2573 MB (80%)
 
     V myvol                 State: up       Plexes:       1 Size:        512 MB
     V mirror                State: up       Plexes:       2 Size:        512 MB
 
     P myvol.p0            C State: up       Subdisks:     1 Size:        512 MB
     P mirror.p0           C State: up       Subdisks:     1 Size:        512 MB
     P mirror.p1           C State: initializing     Subdisks:     1 Size:        512 MB
 
     S myvol.p0.s0           State: up       PO:        0  B Size:        512 MB
 	S mirror.p0.s0          State: up       PO:        0  B Size:        512 MB
 	S mirror.p1.s0          State: empty    PO:        0  B Size:        512 MB
 ....
 
 <<vinum-mirrored-vol, A Mirrored [.filename]#vinum# Volume>> shows the structure graphically.
 
 [[vinum-mirrored-vol]]
 .A Mirrored [.filename]#vinum# Volume
 image::vinum-mirrored-vol.png[]
 
 In this example, each plex contains the full 512 MB of address space.
 As in the previous example, each plex contains only a single subdisk.
 
 === Optimizing Performance
 
 The mirrored volume in the previous example is more resistant to failure than an unmirrored volume, but its performance is less as each write to the volume requires a write to both drives, using up a greater proportion of the total disk bandwidth.
 Performance considerations demand a different approach: instead of mirroring, the data is striped across as many disk drives as possible.
 The following configuration shows a volume with a plex striped across four disk drives:
 
 [.programlisting]
 ....
         drive c device /dev/da5h
 	drive d device /dev/da6h
 	volume stripe
 	plex org striped 512k
 	  sd length 128m drive a
 	  sd length 128m drive b
 	  sd length 128m drive c
 	  sd length 128m drive d
 ....
 
 As before, it is not necessary to define the drives which are already known to [.filename]#vinum#.
 After processing this definition, the configuration looks like:
 
 [.programlisting]
 ....
 
 	Drives:         4 (4 configured)
 	Volumes:        3 (4 configured)
 	Plexes:         4 (8 configured)
 	Subdisks:       7 (16 configured)
 
     D a                     State: up       Device /dev/da3h        Avail: 1421/2573 MB (55%)
     D b                     State: up       Device /dev/da4h        Avail: 1933/2573 MB (75%)
     D c                     State: up       Device /dev/da5h        Avail: 2445/2573 MB (95%)
     D d                     State: up       Device /dev/da6h        Avail: 2445/2573 MB (95%)
 
     V myvol                 State: up       Plexes:       1 Size:        512 MB
     V mirror                State: up       Plexes:       2 Size:        512 MB
     V striped               State: up       Plexes:       1 Size:        512 MB
 
     P myvol.p0            C State: up       Subdisks:     1 Size:        512 MB
     P mirror.p0           C State: up       Subdisks:     1 Size:        512 MB
     P mirror.p1           C State: initializing     Subdisks:     1 Size:        512 MB
     P striped.p1            State: up       Subdisks:     1 Size:        512 MB
 
     S myvol.p0.s0           State: up       PO:        0  B Size:        512 MB
     S mirror.p0.s0          State: up       PO:        0  B Size:        512 MB
     S mirror.p1.s0          State: empty    PO:        0  B Size:        512 MB
     S striped.p0.s0         State: up       PO:        0  B Size:        128 MB
     S striped.p0.s1         State: up       PO:      512 kB Size:        128 MB
     S striped.p0.s2         State: up       PO:     1024 kB Size:        128 MB
     S striped.p0.s3         State: up       PO:     1536 kB Size:        128 MB
 ....
 
 [[vinum-striped-vol]]
 .A Striped [.filename]#vinum# Volume
 image::vinum-striped-vol.png[]
 
 This volume is represented in <<vinum-striped-vol, A Striped [.filename]#vinum# Volume>>.
 The darkness of the stripes indicates the position within the plex address space, where the lightest stripes come first and the darkest last.
 
 === Resilience and Performance
 
 [[vinum-resilience]]With sufficient hardware, it is possible to build volumes which show both increased resilience and increased performance compared to standard UNIX(R) partitions.
 A typical configuration file might be:
 
 [.programlisting]
 ....
 	volume raid10
       plex org striped 512k
         sd length 102480k drive a
         sd length 102480k drive b
         sd length 102480k drive c
         sd length 102480k drive d
         sd length 102480k drive e
       plex org striped 512k
         sd length 102480k drive c
         sd length 102480k drive d
         sd length 102480k drive e
         sd length 102480k drive a
         sd length 102480k drive b
 ....
 
 The subdisks of the second plex are offset by two drives from those of the first plex.
 This helps to ensure that writes do not go to the same subdisks even if a transfer goes over two drives.
 
 <<vinum-raid10-vol, A Mirrored, Striped [.filename]#vinum# Volume>> represents the structure of this volume.
 
 [[vinum-raid10-vol]]
 .A Mirrored, Striped [.filename]#vinum# Volume
 image::vinum-raid10-vol.png[]
 
 [[vinum-object-naming]]
 == Object Naming
 
 [.filename]#vinum# assigns default names to plexes and subdisks, although they may be overridden.
 Overriding the default names is not recommended as it does not bring a significant advantage and it can cause confusion.
 
 Names may contain any non-blank character, but it is recommended to restrict them to letters, digits and the underscore characters.
 The names of volumes, plexes, and subdisks may be up to 64 characters long, and the names of drives may be up to 32 characters long.
 
 [.filename]#vinum# objects are assigned device nodes in the hierarchy [.filename]#/dev/gvinum#.
 The configuration shown above would cause [.filename]#vinum# to create the following device nodes:
 
 * Device entries for each volume. These are the main devices used by [.filename]#vinum#. The configuration above would include the devices [.filename]#/dev/gvinum/myvol#, [.filename]#/dev/gvinum/mirror#, [.filename]#/dev/gvinum/striped#, [.filename]#/dev/gvinum/raid5# and [.filename]#/dev/gvinum/raid10#.
 * All volumes get direct entries under [.filename]#/dev/gvinum/#.
 * The directories [.filename]#/dev/gvinum/plex#, and [.filename]#/dev/gvinum/sd#, which contain device nodes for each plex and for each subdisk, respectively.
 
 For example, consider the following configuration file:
 
 [.programlisting]
 ....
 	drive drive1 device /dev/sd1h
 	drive drive2 device /dev/sd2h
 	drive drive3 device /dev/sd3h
 	drive drive4 device /dev/sd4h
     volume s64 setupstate
       plex org striped 64k
         sd length 100m drive drive1
         sd length 100m drive drive2
         sd length 100m drive drive3
         sd length 100m drive drive4
 ....
 
 After processing this file, man:gvinum[8] creates the following structure in [.filename]#/dev/gvinum#:
 
 [.programlisting]
 ....
 	drwxr-xr-x  2 root  wheel       512 Apr 13
 16:46 plex
 	crwxr-xr--  1 root  wheel   91,   2 Apr 13 16:46 s64
 	drwxr-xr-x  2 root  wheel       512 Apr 13 16:46 sd
 
     /dev/vinum/plex:
     total 0
     crwxr-xr--  1 root  wheel   25, 0x10000002 Apr 13 16:46 s64.p0
 
     /dev/vinum/sd:
     total 0
     crwxr-xr--  1 root  wheel   91, 0x20000002 Apr 13 16:46 s64.p0.s0
     crwxr-xr--  1 root  wheel   91, 0x20100002 Apr 13 16:46 s64.p0.s1
     crwxr-xr--  1 root  wheel   91, 0x20200002 Apr 13 16:46 s64.p0.s2
     crwxr-xr--  1 root  wheel   91, 0x20300002 Apr 13 16:46 s64.p0.s3
 ....
 
 Although it is recommended that plexes and subdisks should not be allocated specific names, [.filename]#vinum# drives must be named.
 This makes it possible to move a drive to a different location and still recognize it automatically.
 Drive names may be up to 32 characters long.
 
 === Creating File Systems
 
 Volumes appear to the system to be identical to disks, with one exception.
 Unlike UNIX(R) drives, [.filename]#vinum# does not partition volumes, which thus do not contain a partition table.
 This has required modification to some disk utilities, notably man:newfs[8], so that it does not try to interpret the last letter of a [.filename]#vinum# volume name as a partition identifier.
 For example, a disk drive may have a name like [.filename]#/dev/ad0a# or [.filename]#/dev/da2h#.
 These names represent the first partition ([.filename]#a#) on the first (0) IDE disk ([.filename]#ad#) and the eighth partition ([.filename]#h#) on the third (2) SCSI disk ([.filename]#da#) respectively.
 By contrast, a [.filename]#vinum# volume might be called [.filename]#/dev/gvinum/concat#, which has no relationship with a partition name.
 
 In order to create a file system on this volume, use man:newfs[8]:
 
 [source,shell]
 ....
 # newfs /dev/gvinum/concat
 ....
 
 [[vinum-config]]
 == Configuring [.filename]#vinum#
 
 The [.filename]#GENERIC# kernel does not contain [.filename]#vinum#.
 It is possible to build a custom kernel which includes [.filename]#vinum#, but this is not recommended.
 The standard way to start [.filename]#vinum# is as a kernel module.
 man:kldload[8] is not needed because when man:gvinum[8] starts, it checks whether the module has been loaded, and if it is not, it loads it automatically.
 
 === Startup
 
 [.filename]#vinum# stores configuration information on the disk slices in essentially the same form as in the configuration files.
 When reading from the configuration database, [.filename]#vinum# recognizes a number of keywords which are not allowed in the configuration files.
 For example, a disk configuration might contain the following text:
 
 [.programlisting]
 ....
 volume myvol state up
 volume bigraid state down
 plex name myvol.p0 state up org concat vol myvol
 plex name myvol.p1 state up org concat vol myvol
 plex name myvol.p2 state init org striped 512b vol myvol
 plex name bigraid.p0 state initializing org raid5 512b vol bigraid
 sd name myvol.p0.s0 drive a plex myvol.p0 state up len 1048576b driveoffset 265b plexoffset 0b
 sd name myvol.p0.s1 drive b plex myvol.p0 state up len 1048576b driveoffset 265b plexoffset 1048576b
 sd name myvol.p1.s0 drive c plex myvol.p1 state up len 1048576b driveoffset 265b plexoffset 0b
 sd name myvol.p1.s1 drive d plex myvol.p1 state up len 1048576b driveoffset 265b plexoffset 1048576b
 sd name myvol.p2.s0 drive a plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 0b
 sd name myvol.p2.s1 drive b plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 524288b
 sd name myvol.p2.s2 drive c plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 1048576b
 sd name myvol.p2.s3 drive d plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 1572864b
 sd name bigraid.p0.s0 drive a plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 0b
 sd name bigraid.p0.s1 drive b plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 4194304b
 sd name bigraid.p0.s2 drive c plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 8388608b
 sd name bigraid.p0.s3 drive d plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 12582912b
 sd name bigraid.p0.s4 drive e plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 16777216b
 ....
 
 The obvious differences here are the presence of explicit location information and naming, both of which are allowed but discouraged, and the information on the states.
 [.filename]#vinum# does not store information about drives in the configuration information.
 It finds the drives by scanning the configured disk drives for partitions with a [.filename]#vinum# label.
 This enables [.filename]#vinum# to identify drives correctly even if they have been assigned different UNIX(R) drive IDs.
 
 [[vinum-rc-startup]]
 ==== Automatic Startup
 
 _Gvinum_ always features an automatic startup once the kernel module is loaded, via man:loader.conf[5].
 To load the _Gvinum_ module at boot time, add `geom_vinum_load="YES"` to [.filename]#/boot/loader.conf#.
 
 When [.filename]#vinum# is started with `gvinum start`, [.filename]#vinum# reads the configuration database from one of the [.filename]#vinum# drives. 
 Under normal circumstances, each drive contains an identical copy of the configuration database, so it does not matter which drive is read.
 After a crash, however, [.filename]#vinum# must determine which drive was updated most recently and read the configuration from this drive.
 It then updates the configuration, if necessary, from progressively older drives.
 
 [[vinum-root]]
 == Using [.filename]#vinum# for the Root File System
 
 For a machine that has fully-mirrored file systems using [.filename]#vinum#, it is desirable to also mirror the root file system.
 Setting up such a configuration is less trivial than mirroring an arbitrary file system because:
 
 * The root file system must be available very early during the boot process, so the [.filename]#vinum# infrastructure must already be available at this time.
 * The volume containing the root file system also contains the system bootstrap and the kernel. These must be read using the host system's native utilities, such as the BIOS, which often cannot be taught about the details of [.filename]#vinum#.
 
 In the following sections, the term "root volume" is generally used to describe the [.filename]#vinum# volume that contains the root file system.
 
 === Starting up [.filename]#vinum# Early Enough for the Root File System
 
 [.filename]#vinum# must be available early in the system boot as man:loader[8] must be able to load the vinum kernel module before starting the kernel. 
 This can be accomplished by putting this line in [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 geom_vinum_load="YES"
 ....
 
 === Making a [.filename]#vinum#-based Root Volume Accessible to the Bootstrap
 
 The current FreeBSD bootstrap is only 7.5 KB of code and does not understand the internal [.filename]#vinum# structures.
 This means that it cannot parse the [.filename]#vinum# configuration data or figure out the elements of a boot volume.
 Thus, some workarounds are necessary to provide the bootstrap code with the illusion of a standard `a` partition that contains the root file system.
 
 For this to be possible, the following requirements must be met for the root volume:
 
 * The root volume must not be a stripe or `RAID`-5.
 * The root volume must not contain more than one concatenated subdisk per plex.
 
 Note that it is desirable and possible to use multiple plexes, each containing one replica of the root file system.
 The bootstrap process will only use one replica for finding the bootstrap and all boot files, until the kernel mounts the root file system.
 Each single subdisk within these plexes needs its own `a` partition illusion, for the respective device to be bootable.
 It is not strictly needed that each of these faked `a` partitions is located at the same offset within its device, compared with other devices containing plexes of the root volume.
 However, it is probably a good idea to create the [.filename]#vinum# volumes that way so the resulting mirrored devices are symmetric, to avoid confusion.
 
 In order to set up these `a` partitions for each device containing part of the root volume, the following is required:
 
 [.procedure]
 ====
 . The location, offset from the beginning of the device, and size of this device's subdisk that is part of the root volume needs to be examined, using the command:
 +
 [source,shell]
 ....
 # gvinum l -rv root
 ....
-+ 
++
 [.filename]#vinum# offsets and sizes are measured in bytes.
 They must be divided by 512 in order to obtain the block numbers that are to be used by `bsdlabel`.
 . Run this command for each device that participates in the root volume:
 +
 [source,shell]
 ....
 # bsdlabel -e devname
 ....
-+ 
++
 _devname_ must be either the name of the disk, like [.filename]#da0# for disks without a slice table, or the name of the slice, like [.filename]#ad0s1#.
-+ 
++
 If there is already an `a` partition on the device from a pre-[.filename]#vinum# root file system, it should be renamed to something else so that it remains accessible (just in case), but will no longer be used by default to bootstrap the system.
 A currently mounted root file system cannot be renamed, so this must be executed either when being booted from a "Fixit" media, or in a two-step process where, in a mirror, the disk that is not been currently booted is manipulated first.
-+ 
++
 The offset of the [.filename]#vinum# partition on this device (if any) must be added to the offset of the respective root volume subdisk on this device.
 The resulting value will become the `offset` value for the new `a` partition.
 The `size` value for this partition can be taken verbatim from the calculation above.
 The `fstype` should be `4.2BSD`.
 The `fsize`, `bsize`, and `cpg` values should be chosen to match the actual file system, though they are fairly unimportant within this context.
-+ 
++
 That way, a new `a` partition will be established that overlaps the [.filename]#vinum# partition on this device.
 `bsdlabel` will only allow for this overlap if the [.filename]#vinum# partition has properly been marked using the `vinum` fstype.
 . A faked `a` partition now exists on each device that has one replica of the root volume. It is highly recommendable to verify the result using a command like:
 +
 [source,shell]
 ....
 # fsck -n /dev/devnamea
 ....
 ====
 
 It should be remembered that all files containing control information must be relative to the root file system in the [.filename]#vinum# volume which, when setting up a new [.filename]#vinum# root volume, might not match the root file system that is currently active.
 So in particular, [.filename]#/etc/fstab# and [.filename]#/boot/loader.conf# need to be taken care of.
 
 At next reboot, the bootstrap should figure out the appropriate control information from the new [.filename]#vinum#-based root file system, and act accordingly.
 At the end of the kernel initialization process, after all devices have been announced, the prominent notice that shows the success of this setup is a message like:
 
 [source,shell]
 ....
 Mounting root from ufs:/dev/gvinum/root
 ....
 
 === Example of a [.filename]#vinum#-based Root Setup
 
 After the [.filename]#vinum# root volume has been set up, the output of `gvinum l -rv root` could look like:
 
 [source,shell]
 ....
 ...
 Subdisk root.p0.s0:
 		Size:        125829120 bytes (120 MB)
 		State: up
 		Plex root.p0 at offset 0 (0  B)
 		Drive disk0 (/dev/da0h) at offset 135680 (132 kB)
 
 Subdisk root.p1.s0:
 		Size:        125829120 bytes (120 MB)
 		State: up
 		Plex root.p1 at offset 0 (0  B)
 		Drive disk1 (/dev/da1h) at offset 135680 (132 kB)
 ....
 
 The values to note are `135680` for the offset, relative to partition [.filename]#/dev/da0h#.
 This translates to 265 512-byte disk blocks in `bsdlabel`'s terms.
 Likewise, the size of this root volume is 245760 512-byte blocks.
 [.filename]#/dev/da1h#, containing the second replica of this root volume, has a symmetric setup.
 
 The bsdlabel for these devices might look like:
 
 [source,shell]
 ....
 ...
 8 partitions:
 #        size   offset    fstype   [fsize bsize bps/cpg]
   a:   245760      281    4.2BSD     2048 16384     0  # (Cyl.    0*- 15*)
   c: 71771688        0    unused        0     0        # (Cyl.    0 - 4467*)
   h: 71771672       16     vinum                       # (Cyl.    0*- 4467*)
 ....
 
 It can be observed that the `size` parameter for the faked `a` partition matches the value outlined above, while the `offset` parameter is the sum of the offset within the [.filename]#vinum# partition `h`, and the offset of this partition within the device or slice.
 This is a typical setup that is necessary to avoid the problem described in <<vinum-root-panic, Nothing Boots, the Bootstrap Panics>>.
 The entire `a` partition is completely within the `h` partition containing all the [.filename]#vinum# data for this device.
 
 In the above example, the entire device is dedicated to [.filename]#vinum# and there is no leftover pre-[.filename]#vinum# root partition.
 
 === Troubleshooting
 
 The following list contains a few known pitfalls and solutions.
 
 ==== System Bootstrap Loads, but System Does Not Boot
 
 If for any reason the system does not continue to boot, the bootstrap can be interrupted by pressing kbd:[space] at the 10-seconds warning.
 The loader variable `vinum.autostart` can be examined by typing `show` and manipulated using `set` or `unset`.
 
 If the [.filename]#vinum# kernel module was not yet in the list of modules to load automatically, type `load geom_vinum`.
 
 When ready, the boot process can be continued by typing `boot -as` which `-as` requests the kernel to ask for the root file system to mount (`-a`) and make the boot process stop in single-user mode (`-s`), where the root file system is mounted read-only.
 That way, even if only one plex of a multi-plex volume has been mounted, no data inconsistency between plexes is being risked.
 
 At the prompt asking for a root file system to mount, any device that contains a valid root file system can be entered.
 If [.filename]#/etc/fstab# is set up correctly, the default should be something like `ufs:/dev/gvinum/root`.
 A typical alternate choice would be something like `ufs:da0d` which could be a hypothetical partition containing the pre-[.filename]#vinum# root file system.
 Care should be taken if one of the alias `a` partitions is entered here, that it actually references the subdisks of the [.filename]#vinum# root device, because in a mirrored setup, this would only mount one piece of a mirrored root device.
 If this file system is to be mounted read-write later on, it is necessary to remove the other plex(es) of the [.filename]#vinum# root volume since these plexes would otherwise carry inconsistent data.
 
 ==== Only Primary Bootstrap Loads
 
 If [.filename]#/boot/loader# fails to load, but the primary bootstrap still loads (visible by a single dash in the left column of the screen right after the boot process starts), an attempt can be made to interrupt the primary bootstrap by pressing kbd:[space].
 This will make the bootstrap stop in link:{handbook}#boot-boot1[stage two].
 An attempt can be made here to boot off an alternate partition, like the partition containing the previous root file system that has been moved away from `a`.
 
 [[vinum-root-panic]]
 ==== Nothing Boots, the Bootstrap Panics
 
 This situation will happen if the bootstrap had been destroyed by the [.filename]#vinum# installation.
 Unfortunately, [.filename]#vinum# accidentally leaves only 4 KB at the beginning of its partition free before starting to write its [.filename]#vinum# header information.
 However, the stage one and two bootstraps plus the bsdlabel require 8 KB.
 So if a [.filename]#vinum# partition was started at offset 0 within a slice or disk that was meant to be bootable, the [.filename]#vinum# setup will trash the bootstrap.
 
 Similarly, if the above situation has been recovered, by booting from a "Fixit" media, and the bootstrap has been re-installed using `bsdlabel -B` as described in link:{handbook}#boot-boot1[stage two], the bootstrap will trash the [.filename]#vinum# header, and [.filename]#vinum# will no longer find its disk(s). 
 Though no actual [.filename]#vinum# configuration data or data in [.filename]#vinum# volumes will be trashed, and it would be possible to recover all the data by entering exactly the same [.filename]#vinum# configuration data again, the situation is hard to fix.
 It is necessary to move the entire [.filename]#vinum# partition by at least 4 KB, in order to have the [.filename]#vinum# header and the system bootstrap no longer collide.
diff --git a/documentation/content/en/books/arch-handbook/isa/_index.adoc b/documentation/content/en/books/arch-handbook/isa/_index.adoc
index 3c5681ce77..4120532432 100644
--- a/documentation/content/en/books/arch-handbook/isa/_index.adoc
+++ b/documentation/content/en/books/arch-handbook/isa/_index.adoc
@@ -1,1105 +1,1105 @@
 ---
 title: Chapter 10. ISA Device Drivers
 prev: books/arch-handbook/driverbasics
 next: books/arch-handbook/pci
 description: ISA Device Drivers
 tags: ["ISA", "device drivers", "FreeBSD"]
 ---
 
 [[isa-driver]]
 = ISA Device Drivers
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
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 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 10
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
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 toc::[]
 
 [[isa-driver-synopsis]]
 == Synopsis
 
 This chapter introduces the issues relevant to writing a driver for an ISA device. The pseudo-code presented here is rather detailed and reminiscent of the real code but is still only pseudo-code. It avoids the details irrelevant to the subject of the discussion. The real-life examples can be found in the source code of real drivers. In particular the drivers `ep` and `aha` are good sources of information.
 
 [[isa-driver-basics]]
 == Basic Information
 
 A typical ISA driver would need the following include files:
 
 [.programlisting]
 ....
 #include <sys/module.h>
 #include <sys/bus.h>
 #include <machine/bus.h>
 #include <machine/resource.h>
 #include <sys/rman.h>
 
 #include <isa/isavar.h>
 #include <isa/pnpvar.h>
 ....
 
 They describe the things specific to the ISA and generic bus subsystem.
 
 The bus subsystem is implemented in an object-oriented fashion, its main structures are accessed by associated method functions.
 
 The list of bus methods implemented by an ISA driver is like one for any other bus. For a hypothetical driver named "xxx" they would be:
 
 * `static void xxx_isa_identify (driver_t *, device_t);` Normally used for bus drivers, not device drivers. But for ISA devices this method may have special use: if the device provides some device-specific (non-PnP) way to auto-detect devices this routine may implement it.
 * `static int xxx_isa_probe (device_t dev);` Probe for a device at a known (or PnP) location. This routine can also accommodate device-specific auto-detection of parameters for partially configured devices.
 * `static int xxx_isa_attach (device_t dev);` Attach and initialize device.
 * `static int xxx_isa_detach (device_t dev);` Detach device before unloading the driver module.
 * `static int xxx_isa_shutdown (device_t dev);` Execute shutdown of the device before system shutdown.
 * `static int xxx_isa_suspend (device_t dev);` Suspend the device before the system goes to the power-save state. May also abort transition to the power-save state.
 * `static int xxx_isa_resume (device_t dev);` Resume the device activity after return from power-save state.
 
 `xxx_isa_probe()` and `xxx_isa_attach()` are mandatory, the rest of the routines are optional, depending on the device's needs.
 
 The driver is linked to the system with the following set of descriptions.
 
 [.programlisting]
 ....
     /* table of supported bus methods */
     static device_method_t xxx_isa_methods[] = {
         /* list all the bus method functions supported by the driver */
         /* omit the unsupported methods */
         DEVMETHOD(device_identify,  xxx_isa_identify),
         DEVMETHOD(device_probe,     xxx_isa_probe),
         DEVMETHOD(device_attach,    xxx_isa_attach),
         DEVMETHOD(device_detach,    xxx_isa_detach),
         DEVMETHOD(device_shutdown,  xxx_isa_shutdown),
         DEVMETHOD(device_suspend,   xxx_isa_suspend),
         DEVMETHOD(device_resume,    xxx_isa_resume),
 
 	DEVMETHOD_END
     };
 
     static driver_t xxx_isa_driver = {
         "xxx",
         xxx_isa_methods,
         sizeof(struct xxx_softc),
     };
 
     static devclass_t xxx_devclass;
 
     DRIVER_MODULE(xxx, isa, xxx_isa_driver, xxx_devclass,
         load_function, load_argument);
 ....
 
 Here struct `xxx_softc` is a device-specific structure that contains private driver data and descriptors for the driver's resources. The bus code automatically allocates one softc descriptor per device as needed.
 
 If the driver is implemented as a loadable module then `load_function()` is called to do driver-specific initialization or clean-up when the driver is loaded or unloaded and load_argument is passed as one of its arguments. If the driver does not support dynamic loading (in other words it must always be linked into the kernel) then these values should be set to 0 and the last definition would look like:
 
 [.programlisting]
 ....
  DRIVER_MODULE(xxx, isa, xxx_isa_driver,
        xxx_devclass, 0, 0);
 ....
 
 If the driver is for a device which supports PnP then a table of supported PnP IDs must be defined. The table consists of a list of PnP IDs supported by this driver and human-readable descriptions of the hardware types and models having these IDs. It looks like:
 
 [.programlisting]
 ....
     static struct isa_pnp_id xxx_pnp_ids[] = {
         /* a line for each supported PnP ID */
         { 0x12345678,   "Our device model 1234A" },
         { 0x12345679,   "Our device model 1234B" },
         { 0,        NULL }, /* end of table */
     };
 ....
 
 If the driver does not support PnP devices it still needs an empty PnP ID table, like:
 
 [.programlisting]
 ....
     static struct isa_pnp_id xxx_pnp_ids[] = {
         { 0,        NULL }, /* end of table */
     };
 ....
 
 [[isa-driver-device-t]]
 == `device_t` Pointer
 
 `device_t` is the pointer type for the device structure. Here we consider only the methods interesting from the device driver writer's standpoint. The methods to manipulate values in the device structure are:
 
 * `device_t device_get_parent(dev)` Get the parent bus of a device.
 * `driver_t device_get_driver(dev)` Get pointer to its driver structure.
 * `char *device_get_name(dev)` Get the driver name, such as `"xxx"` for our example.
 * `int device_get_unit(dev)` Get the unit number (units are numbered from 0 for the devices associated with each driver).
 * `char *device_get_nameunit(dev)` Get the device name including the unit number, such as "xxx0", "xxx1" and so on.
 * `char *device_get_desc(dev)` Get the device description. Normally it describes the exact model of device in human-readable form.
 * `device_set_desc(dev, desc)` Set the description. This makes the device description point to the string desc which may not be deallocated or changed after that.
 * `device_set_desc_copy(dev, desc)` Set the description. The description is copied into an internal dynamically allocated buffer, so the string desc may be changed afterwards without adverse effects.
 * `void *device_get_softc(dev)` Get pointer to the device descriptor (struct `xxx_softc`) associated with this device.
 * `u_int32_t device_get_flags(dev)` Get the flags specified for the device in the configuration file.
 
 A convenience function `device_printf(dev, fmt, ...)` may be used to print the messages from the device driver. It automatically prepends the unitname and colon to the message.
 
 The device_t methods are implemented in the file [.filename]#kern/bus_subr.c#.
 
 [[isa-driver-config]]
 == Configuration File and the Order of Identifying and Probing During Auto-Configuration
 
 The ISA devices are described in the kernel configuration file like:
 
 [.programlisting]
 ....
 device xxx0 at isa? port 0x300 irq 10 drq 5
        iomem 0xd0000 flags 0x1 sensitive
 ....
 
 The values of port, IRQ and so on are converted to the resource values associated with the device. They are optional, depending on the device's needs and abilities for auto-configuration. For example, some devices do not need DRQ at all and some allow the driver to read the IRQ setting from the device configuration ports. If a machine has multiple ISA buses the exact bus may be specified in the configuration line, like `isa0` or `isa1`, otherwise the device would be searched for on all the ISA buses.
 
 `sensitive` is a resource requesting that this device must be probed before all non-sensitive devices. It is supported but does not seem to be used in any current driver.
 
 For legacy ISA devices in many cases the drivers are still able to detect the configuration parameters. But each device to be configured in the system must have a config line. If two devices of some type are installed in the system but there is only one configuration line for the corresponding driver, ie: 
 [.programlisting]
 ....
 device xxx0 at isa?
 ....
  then only one device will be configured.
 
 But for the devices supporting automatic identification by the means of Plug-n-Play or some proprietary protocol one configuration line is enough to configure all the devices in the system, like the one above or just simply:
 
 [.programlisting]
 ....
 device xxx at isa?
 ....
 
 If a driver supports both auto-identified and legacy devices and both kinds are installed at once in one machine then it is enough to describe in the config file the legacy devices only. The auto-identified devices will be added automatically.
 
 When an ISA bus is auto-configured the events happen as follows:
 
 All the drivers' identify routines (including the PnP identify routine which identifies all the PnP devices) are called in random order. As they identify the devices they add them to the list on the ISA bus. Normally the drivers' identify routines associate their drivers with the new devices. The PnP identify routine does not know about the other drivers yet so it does not associate any with the new devices it adds.
 
 The PnP devices are put to sleep using the PnP protocol to prevent them from being probed as legacy devices.
 
 The probe routines of non-PnP devices marked as `sensitive` are called. If probe for a device went successfully, the attach routine is called for it.
 
 The probe and attach routines of all non-PNP devices are called likewise.
 
 The PnP devices are brought back from the sleep state and assigned the resources they request: I/O and memory address ranges, IRQs and DRQs, all of them not conflicting with the attached legacy devices.
 
 Then for each PnP device the probe routines of all the present ISA drivers are called. The first one that claims the device gets attached. It is possible that multiple drivers would claim the device with different priority; in this case, the highest-priority driver wins. The probe routines must call `ISA_PNP_PROBE()` to compare the actual PnP ID with the list of the IDs supported by the driver and if the ID is not in the table return failure. That means that absolutely every driver, even the ones not supporting any PnP devices must call `ISA_PNP_PROBE()`, at least with an empty PnP ID table to return failure on unknown PnP devices.
 
 The probe routine returns a positive value (the error code) on error, zero or negative value on success.
 
 The negative return values are used when a PnP device supports multiple interfaces. For example, an older compatibility interface and a newer advanced interface which are supported by different drivers. Then both drivers would detect the device. The driver which returns a higher value in the probe routine takes precedence (in other words, the driver returning 0 has highest precedence, returning -1 is next, returning -2 is after it and so on). In result the devices which support only the old interface will be handled by the old driver (which should return -1 from the probe routine) while the devices supporting the new interface as well will be handled by the new driver (which should return 0 from the probe routine). If multiple drivers return the same value then the one called first wins. So if a driver returns value 0 it may be sure that it won the priority arbitration.
 
 The device-specific identify routines can also assign not a driver but a class of drivers to the device. Then all the drivers in the class are probed for this device, like the case with PnP. This feature is not implemented in any existing driver and is not considered further in this document.
 
 As the PnP devices are disabled when probing the legacy devices they will not be attached twice (once as legacy and once as PnP). But in case of device-dependent identify routines it is the responsibility of the driver to make sure that the same device will not be attached by the driver twice: once as legacy user-configured and once as auto-identified.
 
 Another practical consequence for the auto-identified devices (both PnP and device-specific) is that the flags can not be passed to them from the kernel configuration file. So they must either not use the flags at all or use the flags from the device unit 0 for all the auto-identified devices or use the sysctl interface instead of flags.
 
 Other unusual configurations may be accommodated by accessing the configuration resources directly with functions of families `resource_query_*()` and `resource_*_value()`. Their implementations are located in [.filename]#kern/subr_bus.c#. The old IDE disk driver [.filename]#i386/isa/wd.c# contains examples of such use. But the standard means of configuration must always be preferred. Leave parsing the configuration resources to the bus configuration code.
 
 [[isa-driver-resources]]
 == Resources
 
 The information that a user enters into the kernel configuration file is processed and passed to the kernel as configuration resources. This information is parsed by the bus configuration code and transformed into a value of structure device_t and the bus resources associated with it. The drivers may access the configuration resources directly using functions `resource_*` for more complex cases of configuration. However, generally this is neither needed nor recommended, so this issue is not discussed further here.
 
 The bus resources are associated with each device. They are identified by type and number within the type. For the ISA bus the following types are defined:
 
 * _SYS_RES_IRQ_ - interrupt number
 * _SYS_RES_DRQ_ - ISA DMA channel number
 * _SYS_RES_MEMORY_ - range of device memory mapped into the system memory space 
 * _SYS_RES_IOPORT_ - range of device I/O registers
 
 The enumeration within types starts from 0, so if a device has two memory regions it would have resources of type `SYS_RES_MEMORY` numbered 0 and 1. The resource type has nothing to do with the C language type, all the resource values have the C language type `unsigned long` and must be cast as necessary. The resource numbers do not have to be contiguous, although for ISA they normally would be. The permitted resource numbers for ISA devices are:
 
 [.programlisting]
 ....
           IRQ: 0-1
           DRQ: 0-1
           MEMORY: 0-3
           IOPORT: 0-7
 ....
 
 All the resources are represented as ranges, with a start value and count. For IRQ and DRQ resources the count would normally be equal to 1. The values for memory refer to the physical addresses.
 
 Three types of activities can be performed on resources:
 
 * set/get
 * allocate/release
 * activate/deactivate
 
 Setting sets the range used by the resource. Allocation reserves the requested range that no other driver would be able to reserve it (and checking that no other driver reserved this range already). Activation makes the resource accessible to the driver by doing whatever is necessary for that (for example, for memory it would be mapping into the kernel virtual address space).
 
 The functions to manipulate resources are:
 
 * `int bus_set_resource(device_t dev, int type, int rid, u_long start, u_long count)`
-+ 
++
 Set a range for a resource. Returns 0 if successful, error code otherwise. Normally, this function will return an error only if one of `type`, `rid`, `start` or `count` has a value that falls out of the permitted range.
 
 ** dev - driver's device
 ** type - type of resource, SYS_RES_* 
 ** rid - resource number (ID) within type 
 ** start, count - resource range 
 
 * `int bus_get_resource(device_t dev, int type, int rid, u_long *startp, u_long *countp)`
-+ 
++
 Get the range of resource. Returns 0 if successful, error code if the resource is not defined yet.
 * `u_long bus_get_resource_start(device_t dev, int type, int rid) u_long bus_get_resource_count (device_t dev, int type, int rid)`
-+ 
++
 Convenience functions to get only the start or count. Return 0 in case of error, so if the resource start has 0 among the legitimate values it would be impossible to tell if the value is 0 or an error occurred. Luckily, no ISA resources for add-on drivers may have a start value equal to 0.
 * `void bus_delete_resource(device_t dev, int type, int rid)`
-+ 
++
 Delete a resource, make it undefined.
 * `struct resource * bus_alloc_resource(device_t dev, int type, int *rid, u_long start, u_long end, u_long count, u_int flags)`
-+ 
++
 Allocate a resource as a range of count values not allocated by anyone else, somewhere between start and end. Alas, alignment is not supported. If the resource was not set yet it is automatically created. The special values of start 0 and end ~0 (all ones) means that the fixed values previously set by `bus_set_resource()` must be used instead: start and count as themselves and end=(start+count), in this case if the resource was not defined before then an error is returned. Although rid is passed by reference it is not set anywhere by the resource allocation code of the ISA bus. (The other buses may use a different approach and modify it).
 
 Flags are a bitmap, the flags interesting for the caller are:
 
 * _RF_ACTIVE_ - causes the resource to be automatically activated after allocation.
 * _RF_SHAREABLE_ - resource may be shared at the same time by multiple drivers.
 * _RF_TIMESHARE_ - resource may be time-shared by multiple drivers, i.e., allocated at the same time by many but activated only by one at any given moment of time.
 * Returns 0 on error. The allocated values may be obtained from the returned handle using methods `rhand_*()`.
 * `int bus_release_resource(device_t dev, int type, int rid, struct resource *r)`
 * Release the resource, r is the handle returned by `bus_alloc_resource()`. Returns 0 on success, error code otherwise.
 * `int bus_activate_resource(device_t dev, int type, int rid, struct resource *r) int bus_deactivate_resource(device_t dev, int type, int rid, struct resource *r)`
 * Activate or deactivate resource. Return 0 on success, error code otherwise. If the resource is time-shared and currently activated by another driver then `EBUSY` is returned.
 * `int bus_setup_intr(device_t dev, struct resource *r, int flags, driver_intr_t *handler, void *arg, void **cookiep) int bus_teardown_intr(device_t dev, struct resource *r, void *cookie)`
 * Associate or de-associate the interrupt handler with a device. Return 0 on success, error code otherwise.
 * r - the activated resource handler describing the IRQ
-+ 
++
 flags - the interrupt priority level, one of:
 
 ** `INTR_TYPE_TTY` - terminals and other likewise character-type devices. To mask them use `spltty()`.
 ** `(INTR_TYPE_TTY | INTR_TYPE_FAST)` - terminal type devices with small input buffer, critical to the data loss on input (such as the old-fashioned serial ports). To mask them use `spltty()`.
 ** `INTR_TYPE_BIO` - block-type devices, except those on the CAM controllers. To mask them use `splbio()`.
 ** `INTR_TYPE_CAM` - CAM (Common Access Method) bus controllers. To mask them use `splcam()`.
 ** `INTR_TYPE_NET` - network interface controllers. To mask them use `splimp()`.
 ** `INTR_TYPE_MISC` - miscellaneous devices. There is no other way to mask them than by `splhigh()` which masks all interrupts.
 
 When an interrupt handler executes all the other interrupts matching its priority level will be masked. The only exception is the MISC level for which no other interrupts are masked and which is not masked by any other interrupt.
 
 * _handler_ - pointer to the handler function, the type driver_intr_t is defined as `void driver_intr_t(void *)`
 * _arg_ - the argument passed to the handler to identify this particular device. It is cast from void* to any real type by the handler. The old convention for the ISA interrupt handlers was to use the unit number as argument, the new (recommended) convention is using a pointer to the device softc structure.
 * _cookie[p]_ - the value received from `setup()` is used to identify the handler when passed to `teardown()`
 
 A number of methods are defined to operate on the resource handlers (struct resource *). Those of interest to the device driver writers are:
 
 * `u_long rman_get_start(r) u_long rman_get_end(r)` Get the start and end of allocated resource range.
 * `void *rman_get_virtual(r)` Get the virtual address of activated memory resource.
 
 [[isa-driver-busmem]]
 == Bus Memory Mapping
 
 In many cases data is exchanged between the driver and the device through the memory. Two variants are possible:
 
 (a) memory is located on the device card
 
 (b) memory is the main memory of the computer
 
 In case (a) the driver always copies the data back and forth between the on-card memory and the main memory as necessary. To map the on-card memory into the kernel virtual address space the physical address and length of the on-card memory must be defined as a `SYS_RES_MEMORY` resource. That resource can then be allocated and activated, and its virtual address obtained using `rman_get_virtual()`. The older drivers used the function `pmap_mapdev()` for this purpose, which should not be used directly any more. Now it is one of the internal steps of resource activation.
 
 Most of the ISA cards will have their memory configured for physical location somewhere in range 640KB-1MB. Some of the ISA cards require larger memory ranges which should be placed somewhere under 16MB (because of the 24-bit address limitation on the ISA bus). In that case if the machine has more memory than the start address of the device memory (in other words, they overlap) a memory hole must be configured at the address range used by devices. Many BIOSes allow configuration of a memory hole of 1MB starting at 14MB or 15MB. FreeBSD can handle the memory holes properly if the BIOS reports them properly (this feature may be broken on old BIOSes).
 
 In case (b) just the address of the data is sent to the device, and the device uses DMA to actually access the data in the main memory. Two limitations are present: First, ISA cards can only access memory below 16MB. Second, the contiguous pages in virtual address space may not be contiguous in physical address space, so the device may have to do scatter/gather operations. The bus subsystem provides ready solutions for some of these problems, the rest has to be done by the drivers themselves.
 
 Two structures are used for DMA memory allocation, `bus_dma_tag_t` and `bus_dmamap_t`. Tag describes the properties required for the DMA memory. Map represents a memory block allocated according to these properties. Multiple maps may be associated with the same tag.
 
 Tags are organized into a tree-like hierarchy with inheritance of the properties. A child tag inherits all the requirements of its parent tag, and may make them more strict but never more loose.
 
 Normally one top-level tag (with no parent) is created for each device unit. If multiple memory areas with different requirements are needed for each device then a tag for each of them may be created as a child of the parent tag.
 
 The tags can be used to create a map in two ways.
 
 First, a chunk of contiguous memory conformant with the tag requirements may be allocated (and later may be freed). This is normally used to allocate relatively long-living areas of memory for communication with the device. Loading of such memory into a map is trivial: it is always considered as one chunk in the appropriate physical memory range.
 
 Second, an arbitrary area of virtual memory may be loaded into a map. Each page of this memory will be checked for conformance to the map requirement. If it conforms then it is left at its original location. If it is not then a fresh conformant "bounce page" is allocated and used as intermediate storage. When writing the data from the non-conformant original pages they will be copied to their bounce pages first and then transferred from the bounce pages to the device. When reading the data would go from the device to the bounce pages and then copied to their non-conformant original pages. The process of copying between the original and bounce pages is called synchronization. This is normally used on a per-transfer basis: buffer for each transfer would be loaded, transfer done and buffer unloaded.
 
 The functions working on the DMA memory are:
 
 * `int bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment, bus_size_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr, bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize, int nsegments, bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat)`
-+ 
++
 Create a new tag. Returns 0 on success, the error code otherwise.
 
 ** _parent_ - parent tag, or NULL to create a top-level tag.
 ** _alignment_ - required physical alignment of the memory area to be allocated for this tag. Use value 1 for "no specific alignment". Applies only to the future `bus_dmamem_alloc()` but not `bus_dmamap_create()` calls.
 ** _boundary_ - physical address boundary that must not be crossed when allocating the memory. Use value 0 for "no boundary". Applies only to the future `bus_dmamem_alloc()` but not `bus_dmamap_create()` calls. Must be power of 2. If the memory is planned to be used in non-cascaded DMA mode (i.e., the DMA addresses will be supplied not by the device itself but by the ISA DMA controller) then the boundary must be no larger than 64KB (64*1024) due to the limitations of the DMA hardware.
 ** _lowaddr, highaddr_ - the names are slightly misleading; these values are used to limit the permitted range of physical addresses used to allocate the memory. The exact meaning varies depending on the planned future use:
 
 *** For `bus_dmamem_alloc()` all the addresses from 0 to lowaddr-1 are considered permitted, the higher ones are forbidden.
 *** For `bus_dmamap_create()` all the addresses outside the inclusive range [lowaddr; highaddr] are considered accessible. The addresses of pages inside the range are passed to the filter function which decides if they are accessible. If no filter function is supplied then all the range is considered unaccessible.
 *** For the ISA devices the normal values (with no filter function) are:
-+ 
++
 lowaddr = BUS_SPACE_MAXADDR_24BIT
-+ 
++
 highaddr = BUS_SPACE_MAXADDR
 
 ** _filter, filterarg_ - the filter function and its argument. If NULL is passed for filter then the whole range [lowaddr, highaddr] is considered unaccessible when doing `bus_dmamap_create()`. Otherwise the physical address of each attempted page in range [lowaddr; highaddr] is passed to the filter function which decides if it is accessible. The prototype of the filter function is: `int filterfunc(void *arg, bus_addr_t paddr)`. It must return 0 if the page is accessible, non-zero otherwise.
 ** _maxsize_ - the maximal size of memory (in bytes) that may be allocated through this tag. In case it is difficult to estimate or could be arbitrarily big, the value for ISA devices would be `BUS_SPACE_MAXSIZE_24BIT`.
 ** _nsegments_ - maximal number of scatter-gather segments supported by the device. If unrestricted then the value `BUS_SPACE_UNRESTRICTED` should be used. This value is recommended for the parent tags, the actual restrictions would then be specified for the descendant tags. Tags with nsegments equal to `BUS_SPACE_UNRESTRICTED` may not be used to actually load maps, they may be used only as parent tags. The practical limit for nsegments seems to be about 250-300, higher values will cause kernel stack overflow (the hardware can not normally support that many scatter-gather buffers anyway).
 ** _maxsegsz_ - maximal size of a scatter-gather segment supported by the device. The maximal value for ISA device would be `BUS_SPACE_MAXSIZE_24BIT`.
 ** _flags_ - a bitmap of flags. The only interesting flags are:
 
 *** _BUS_DMA_ALLOCNOW_ - requests to allocate all the potentially needed bounce pages when creating the tag.
 *** _BUS_DMA_ISA_ - mysterious flag used only on Alpha machines. It is not defined for the i386 machines. Probably it should be used by all the ISA drivers for Alpha machines but it looks like there are no such drivers yet.
 
 ** _dmat_ - pointer to the storage for the new tag to be returned.
 
 * `int bus_dma_tag_destroy(bus_dma_tag_t dmat)`
-+ 
++
 Destroy a tag. Returns 0 on success, the error code otherwise.
-+ 
++
 dmat - the tag to be destroyed.
 * `int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags, bus_dmamap_t *mapp)`
-+ 
++
 Allocate an area of contiguous memory described by the tag. The size of memory to be allocated is tag's maxsize. Returns 0 on success, the error code otherwise. The result still has to be loaded by `bus_dmamap_load()` before being used to get the physical address of the memory.
 
 ** _dmat_ - the tag 
 ** _vaddr_ - pointer to the storage for the kernel virtual address of the allocated area to be returned. 
 ** flags - a bitmap of flags. The only interesting flag is: 
 
 *** _BUS_DMA_NOWAIT_ - if the memory is not immediately available return the error. If this flag is not set then the routine is allowed to sleep until the memory becomes available. 
 
 ** _mapp_ - pointer to the storage for the new map to be returned. 
 
 * `void bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)`
-+ 
++
 Free the memory allocated by `bus_dmamem_alloc()`. At present, freeing of the memory allocated with ISA restrictions is not implemented. Due to this the recommended model of use is to keep and re-use the allocated areas for as long as possible. Do not lightly free some area and then shortly allocate it again. That does not mean that `bus_dmamem_free()` should not be used at all: hopefully it will be properly implemented soon. 
 
 ** _dmat_ - the tag 
 ** _vaddr_ - the kernel virtual address of the memory 
 ** _map_ - the map of the memory (as returned from `bus_dmamem_alloc()`) 
 
 * `int bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)`
-+ 
++
 Create a map for the tag, to be used in `bus_dmamap_load()` later. Returns 0 on success, the error code otherwise. 
 
 ** _dmat_ - the tag 
 ** _flags_ - theoretically, a bit map of flags. But no flags are defined yet, so at present it will be always 0. 
 ** _mapp_ - pointer to the storage for the new map to be returned 
 
 * `int bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)`
-+ 
++
 Destroy a map. Returns 0 on success, the error code otherwise. 
 
 ** dmat - the tag to which the map is associated 
 ** map - the map to be destroyed 
 
 * `int bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf, bus_size_t buflen, bus_dmamap_callback_t *callback, void *callback_arg, int flags)`
-+ 
++
 Load a buffer into the map (the map must be previously created by `bus_dmamap_create()` or `bus_dmamem_alloc()`). All the pages of the buffer are checked for conformance to the tag requirements and for those not conformant the bounce pages are allocated. An array of physical segment descriptors is built and passed to the callback routine. This callback routine is then expected to handle it in some way. The number of bounce buffers in the system is limited, so if the bounce buffers are needed but not immediately available the request will be queued and the callback will be called when the bounce buffers will become available. Returns 0 if the callback was executed immediately or `EINPROGRESS` if the request was queued for future execution. In the latter case the synchronization with queued callback routine is the responsibility of the driver. 
 +
 ** _dmat_ - the tag 
 ** _map_ - the map 
 ** _buf_ - kernel virtual address of the buffer 
 ** _buflen_ - length of the buffer 
 ** _callback_, `callback_arg` - the callback function and its argument 
-+ 
++
 The prototype of callback function is: `void callback(void *arg, bus_dma_segment_t *seg, int nseg, int error)`
 +
 ** _arg_ - the same as callback_arg passed to `bus_dmamap_load()`
 ** _seg_ - array of the segment descriptors 
 ** _nseg_ - number of descriptors in array 
 ** _error_ - indication of the segment number overflow: if it is set to `EFBIG` then the buffer did not fit into the maximal number of segments permitted by the tag. In this case only the permitted number of descriptors will be in the array. Handling of this situation is up to the driver: depending on the desired semantics it can either consider this an error or split the buffer in two and handle the second part separately 
-+ 
++
 Each entry in the segments array contains the fields: 
 +
 ** _ds_addr_ - physical bus address of the segment 
 ** _ds_len_ - length of the segment 
 +
 * `void bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)`
-+ 
++
 unload the map. 
 +
 ** _dmat_ - tag 
 ** _map_ - loaded map 
 +
 * `void bus_dmamap_sync (bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)`
-+ 
++
 Synchronise a loaded buffer with its bounce pages before and after physical transfer to or from device. This is the function that does all the necessary copying of data between the original buffer and its mapped version. The buffers must be synchronized both before and after doing the transfer. 
 +
 ** _dmat_ - tag 
 ** _map_ - loaded map 
 ** _op_ - type of synchronization operation to perform: 
 +
 ** `BUS_DMASYNC_PREREAD` - before reading from device into buffer 
 ** `BUS_DMASYNC_POSTREAD` - after reading from device into buffer 
 ** `BUS_DMASYNC_PREWRITE` - before writing the buffer to device 
 ** `BUS_DMASYNC_POSTWRITE` - after writing the buffer to device 
 
 As of now PREREAD and POSTWRITE are null operations but that may change in the future, so they must not be ignored in the driver. Synchronization is not needed for the memory obtained from `bus_dmamem_alloc()`. 
 
 Before calling the callback function from `bus_dmamap_load()` the segment array is stored in the stack. And it gets pre-allocated for the maximal number of segments allowed by the tag. As a result of this the practical limit for the number of segments on i386 architecture is about 250-300 (the kernel stack is 4KB minus the size of the user structure, size of a segment array entry is 8 bytes, and some space must be left). Since the array is allocated based on the maximal number this value must not be set higher than really needed. Fortunately, for most of hardware the maximal supported number of segments is much lower. But if the driver wants to handle buffers with a very large number of scatter-gather segments it should do that in portions: load part of the buffer, transfer it to the device, load next part of the buffer, and so on. 
 
 Another practical consequence is that the number of segments may limit the size of the buffer. If all the pages in the buffer happen to be physically non-contiguous then the maximal supported buffer size for that fragmented case would be (nsegments * page_size). For example, if a maximal number of 10 segments is supported then on i386 maximal guaranteed supported buffer size would be 40K. If a higher size is desired then special tricks should be used in the driver. 
 
 If the hardware does not support scatter-gather at all or the driver wants to support some buffer size even if it is heavily fragmented then the solution is to allocate a contiguous buffer in the driver and use it as intermediate storage if the original buffer does not fit. 
 
 Below are the typical call sequences when using a map depend on the use of the map. The characters -> are used to show the flow of time. 
 
 For a buffer which stays practically fixed during all the time between attachment and detachment of a device:
 
 bus_dmamem_alloc -> bus_dmamap_load -> ...use buffer... -> -> bus_dmamap_unload -> bus_dmamem_free 
 
 For a buffer that changes frequently and is passed from outside the driver: 
 [.programlisting]
 ....
           bus_dmamap_create ->
           -> bus_dmamap_load -> bus_dmamap_sync(PRE...) -> do transfer ->
           -> bus_dmamap_sync(POST...) -> bus_dmamap_unload ->
           ...
           -> bus_dmamap_load -> bus_dmamap_sync(PRE...) -> do transfer ->
           -> bus_dmamap_sync(POST...) -> bus_dmamap_unload ->
           -> bus_dmamap_destroy
 ....
 
 When loading a map created by `bus_dmamem_alloc()` the passed address and size of the buffer must be the same as used in `bus_dmamem_alloc()`. In this case it is guaranteed that the whole buffer will be mapped as one segment (so the callback may be based on this assumption) and the request will be executed immediately (EINPROGRESS will never be returned). All the callback needs to do in this case is to save the physical address. 
 
 A typical example would be: 
 
 [.programlisting]
 ....
           static void
         alloc_callback(void *arg, bus_dma_segment_t *seg, int nseg, int error)
         {
           *(bus_addr_t *)arg = seg[0].ds_addr;
         }
 
           ...
           int error;
           struct somedata {
             ....
           };
           struct somedata *vsomedata; /* virtual address */
           bus_addr_t psomedata; /* physical bus-relative address */
           bus_dma_tag_t tag_somedata;
           bus_dmamap_t map_somedata;
           ...
 
           error=bus_dma_tag_create(parent_tag, alignment,
            boundary, lowaddr, highaddr, /*filter*/ NULL, /*filterarg*/ NULL,
            /*maxsize*/ sizeof(struct somedata), /*nsegments*/ 1,
            /*maxsegsz*/ sizeof(struct somedata), /*flags*/ 0,
            &tag_somedata);
           if(error)
           return error;
 
           error = bus_dmamem_alloc(tag_somedata, &vsomedata, /* flags*/ 0,
              &map_somedata);
           if(error)
              return error;
 
           bus_dmamap_load(tag_somedata, map_somedata, (void *)vsomedata,
              sizeof (struct somedata), alloc_callback,
              (void *) &psomedata, /*flags*/0);
 ....
 
 Looks a bit long and complicated but that is the way to do it. The practical consequence is: if multiple memory areas are allocated always together it would be a really good idea to combine them all into one structure and allocate as one (if the alignment and boundary limitations permit). 
 
 When loading an arbitrary buffer into the map created by `bus_dmamap_create()` special measures must be taken to synchronize with the callback in case it would be delayed. The code would look like: 
 
 [.programlisting]
 ....
           {
            int s;
            int error;
 
            s = splsoftvm();
            error = bus_dmamap_load(
                dmat,
                dmamap,
                buffer_ptr,
                buffer_len,
                callback,
                /*callback_arg*/ buffer_descriptor,
                /*flags*/0);
            if (error == EINPROGRESS) {
                /*
                 * Do whatever is needed to ensure synchronization
                 * with callback. Callback is guaranteed not to be started
                 * until we do splx() or tsleep().
                 */
               }
            splx(s);
           }
 ....
 
 Two possible approaches for the processing of requests are: 
 
 1. If requests are completed by marking them explicitly as done (such as the CAM requests) then it would be simpler to put all the further processing into the callback driver which would mark the request when it is done. Then not much extra synchronization is needed. For the flow control reasons it may be a good idea to freeze the request queue until this request gets completed. 
 
 2. If requests are completed when the function returns (such as classic read or write requests on character devices) then a synchronization flag should be set in the buffer descriptor and `tsleep()` called. Later when the callback gets called it will do its processing and check this synchronization flag. If it is set then the callback should issue a wakeup. In this approach the callback function could either do all the needed processing (just like the previous case) or simply save the segments array in the buffer descriptor. Then after callback completes the calling function could use this saved segments array and do all the processing. 
 
 [[isa-driver-dma]]
 == DMA
 
 The Direct Memory Access (DMA) is implemented in the ISA bus through the DMA controller (actually, two of them but that is an irrelevant detail). To make the early ISA devices simple and cheap the logic of the bus control and address generation was concentrated in the DMA controller. Fortunately, FreeBSD provides a set of functions that mostly hide the annoying details of the DMA controller from the device drivers. 
 
 The simplest case is for the fairly intelligent devices. Like the bus master devices on PCI they can generate the bus cycles and memory addresses all by themselves. The only thing they really need from the DMA controller is bus arbitration. So for this purpose they pretend to be cascaded slave DMA controllers. And the only thing needed from the system DMA controller is to enable the cascaded mode on a DMA channel by calling the following function when attaching the driver: 
 
 `void isa_dmacascade(int channel_number)`
 
 All the further activity is done by programming the device. When detaching the driver no DMA-related functions need to be called. 
 
 For the simpler devices things get more complicated. The functions used are: 
 
 * `int isa_dma_acquire(int chanel_number)`
-+ 
++
 Reserve a DMA channel. Returns 0 on success or EBUSY if the channel was already reserved by this or a different driver. Most of the ISA devices are not able to share DMA channels anyway, so normally this function is called when attaching a device. This reservation was made redundant by the modern interface of bus resources but still must be used in addition to the latter. If not used then later, other DMA routines will panic. 
 * `int isa_dma_release(int chanel_number)`
-+ 
++
 Release a previously reserved DMA channel. No transfers must be in progress when the channel is released (in addition the device must not try to initiate transfer after the channel is released). 
 * `void isa_dmainit(int chan, u_int bouncebufsize)`
-+ 
++
 Allocate a bounce buffer for use with the specified channel. The requested size of the buffer can not exceed 64KB. This bounce buffer will be automatically used later if a transfer buffer happens to be not physically contiguous or outside of the memory accessible by the ISA bus or crossing the 64KB boundary. If the transfers will be always done from buffers which conform to these conditions (such as those allocated by `bus_dmamem_alloc()` with proper limitations) then `isa_dmainit()` does not have to be called. But it is quite convenient to transfer arbitrary data using the DMA controller. The bounce buffer will automatically care of the scatter-gather issues. 
 +
 ** _chan_ - channel number 
 ** _bouncebufsize_ - size of the bounce buffer in bytes 
 +
 * `void isa_dmastart(int flags, caddr_t addr, u_int nbytes, int chan)`
-+ 
++
 Prepare to start a DMA transfer. This function must be called to set up the DMA controller before actually starting transfer on the device. It checks that the buffer is contiguous and falls into the ISA memory range, if not then the bounce buffer is automatically used. If bounce buffer is required but not set up by `isa_dmainit()` or too small for the requested transfer size then the system will panic. In case of a write request with bounce buffer the data will be automatically copied to the bounce buffer. 
 * flags - a bitmask determining the type of operation to be done. The direction bits B_READ and B_WRITE are mutually exclusive. 
 +
 ** B_READ - read from the ISA bus into memory 
 ** B_WRITE - write from the memory to the ISA bus 
 ** B_RAW - if set then the DMA controller will remember the buffer and after the end of transfer will automatically re-initialize itself to repeat transfer of the same buffer again (of course, the driver may change the data in the buffer before initiating another transfer in the device). If not set then the parameters will work only for one transfer, and `isa_dmastart()` will have to be called again before initiating the next transfer. Using B_RAW makes sense only if the bounce buffer is not used. 
 +
 * addr - virtual address of the buffer 
 * nbytes - length of the buffer. Must be less or equal to 64KB. Length of 0 is not allowed: the DMA controller will understand it as 64KB while the kernel code will understand it as 0 and that would cause unpredictable effects. For channels number 4 and higher the length must be even because these channels transfer 2 bytes at a time. In case of an odd length the last byte will not be transferred. 
 * chan - channel number 
 * `void isa_dmadone(int flags, caddr_t addr, int nbytes, int chan)`
-+ 
++
 Synchronize the memory after device reports that transfer is done. If that was a read operation with a bounce buffer then the data will be copied from the bounce buffer to the original buffer. Arguments are the same as for `isa_dmastart()`. Flag B_RAW is permitted but it does not affect `isa_dmadone()` in any way. 
 * `int isa_dmastatus(int channel_number)`
-+ 
++
 Returns the number of bytes left in the current transfer to be transferred. In case the flag B_READ was set in `isa_dmastart()` the number returned will never be equal to zero. At the end of transfer it will be automatically reset back to the length of buffer. The normal use is to check the number of bytes left after the device signals that the transfer is completed. If the number of bytes is not 0 then something probably went wrong with that transfer. 
 * `int isa_dmastop(int channel_number)`
-+ 
++
 Aborts the current transfer and returns the number of bytes left untransferred. 
 
 [[isa-driver-probe]]
 == xxx_isa_probe
 
 This function probes if a device is present. If the driver supports auto-detection of some part of device configuration (such as interrupt vector or memory address) this auto-detection must be done in this routine. 
 
 As for any other bus, if the device cannot be detected or is detected but failed the self-test or some other problem happened then it returns a positive value of error. The value `ENXIO` must be returned if the device is not present. Other error values may mean other conditions. Zero or negative values mean success. Most of the drivers return zero as success. 
 
 The negative return values are used when a PnP device supports multiple interfaces. For example, an older compatibility interface and a newer advanced interface which are supported by different drivers. Then both drivers would detect the device. The driver which returns a higher value in the probe routine takes precedence (in other words, the driver returning 0 has highest precedence, one returning -1 is next, one returning -2 is after it and so on). In result the devices which support only the old interface will be handled by the old driver (which should return -1 from the probe routine) while the devices supporting the new interface as well will be handled by the new driver (which should return 0 from the probe routine). 
 
 The device descriptor struct xxx_softc is allocated by the system before calling the probe routine. If the probe routine returns an error the descriptor will be automatically deallocated by the system. So if a probing error occurs the driver must make sure that all the resources it used during probe are deallocated and that nothing keeps the descriptor from being safely deallocated. If the probe completes successfully the descriptor will be preserved by the system and later passed to the routine `xxx_isa_attach()`. If a driver returns a negative value it can not be sure that it will have the highest priority and its attach routine will be called. So in this case it also must release all the resources before returning and if necessary allocate them again in the attach routine. When `xxx_isa_probe()` returns 0 releasing the resources before returning is also a good idea and a well-behaved driver should do so. But in cases where there is some problem with releasing the resources the driver is allowed to keep resources between returning 0 from the probe routine and execution of the attach routine. 
 
 A typical probe routine starts with getting the device descriptor and unit: 
 
 [.programlisting]
 ....
          struct xxx_softc *sc = device_get_softc(dev);
           int unit = device_get_unit(dev);
           int pnperror;
           int error = 0;
 
           sc->dev = dev; /* link it back */
           sc->unit = unit;
 ....
 
 Then check for the PnP devices. The check is carried out by a table containing the list of PnP IDs supported by this driver and human-readable descriptions of the device models corresponding to these IDs. 
 
 [.programlisting]
 ....
 
         pnperror=ISA_PNP_PROBE(device_get_parent(dev), dev,
         xxx_pnp_ids); if(pnperror == ENXIO) return ENXIO;
 ....
 
 The logic of ISA_PNP_PROBE is the following: If this card (device unit) was not detected as PnP then ENOENT will be returned. If it was detected as PnP but its detected ID does not match any of the IDs in the table then ENXIO is returned. Finally, if it has PnP support and it matches on of the IDs in the table, 0 is returned and the appropriate description from the table is set by `device_set_desc()`. 
 
 If a driver supports only PnP devices then the condition would look like: 
 
 [.programlisting]
 ....
           if(pnperror != 0)
               return pnperror;
 ....
 
 No special treatment is required for the drivers which do not support PnP because they pass an empty PnP ID table and will always get ENXIO if called on a PnP card. 
 
 The probe routine normally needs at least some minimal set of resources, such as I/O port number to find the card and probe it. Depending on the hardware the driver may be able to discover the other necessary resources automatically. The PnP devices have all the resources pre-set by the PnP subsystem, so the driver does not need to discover them by itself. 
 
 Typically the minimal information required to get access to the device is the I/O port number. Then some devices allow to get the rest of information from the device configuration registers (though not all devices do that). So first we try to get the port start value: 
 
 [.programlisting]
 ....
  sc->port0 = bus_get_resource_start(dev,
         SYS_RES_IOPORT, 0 /*rid*/); if(sc->port0 == 0) return ENXIO;
 ....
 
 The base port address is saved in the structure softc for future use. If it will be used very often then calling the resource function each time would be prohibitively slow. If we do not get a port we just return an error. Some device drivers can instead be clever and try to probe all the possible ports, like this: 
 
 [.programlisting]
 ....
 
           /* table of all possible base I/O port addresses for this device */
           static struct xxx_allports {
               u_short port; /* port address */
               short used; /* flag: if this port is already used by some unit */
           } xxx_allports = {
               { 0x300, 0 },
               { 0x320, 0 },
               { 0x340, 0 },
               { 0, 0 } /* end of table */
           };
 
           ...
           int port, i;
           ...
 
           port =  bus_get_resource_start(dev, SYS_RES_IOPORT, 0 /*rid*/);
           if(port !=0 ) {
               for(i=0; xxx_allports[i].port!=0; i++) {
                   if(xxx_allports[i].used || xxx_allports[i].port != port)
                       continue;
 
                   /* found it */
                   xxx_allports[i].used = 1;
                   /* do probe on a known port */
                   return xxx_really_probe(dev, port);
               }
               return ENXIO; /* port is unknown or already used */
           }
 
           /* we get here only if we need to guess the port */
           for(i=0; xxx_allports[i].port!=0; i++) {
               if(xxx_allports[i].used)
                   continue;
 
               /* mark as used - even if we find nothing at this port
                * at least we won't probe it in future
                */
                xxx_allports[i].used = 1;
 
               error = xxx_really_probe(dev, xxx_allports[i].port);
               if(error == 0) /* found a device at that port */
                   return 0;
           }
           /* probed all possible addresses, none worked */
           return ENXIO;
 ....
 
 Of course, normally the driver's `identify()` routine should be used for such things. But there may be one valid reason why it may be better to be done in `probe()`: if this probe would drive some other sensitive device crazy. The probe routines are ordered with consideration of the `sensitive` flag: the sensitive devices get probed first and the rest of the devices later. But the `identify()` routines are called before any probes, so they show no respect to the sensitive devices and may upset them. 
 
 Now, after we got the starting port we need to set the port count (except for PnP devices) because the kernel does not have this information in the configuration file. 
 
 [.programlisting]
 ....
 
          if(pnperror /* only for non-PnP devices */
          && bus_set_resource(dev, SYS_RES_IOPORT, 0, sc->port0,
          XXX_PORT_COUNT)<0)
              return ENXIO;
 ....
 
 Finally allocate and activate a piece of port address space (special values of start and end mean "use those we set by ``bus_set_resource()``"): 
 
 [.programlisting]
 ....
 
           sc->port0_rid = 0;
           sc->port0_r = bus_alloc_resource(dev, SYS_RES_IOPORT,
           &sc->port0_rid,
               /*start*/ 0, /*end*/ ~0, /*count*/ 0, RF_ACTIVE);
 
           if(sc->port0_r == NULL)
               return ENXIO;
 ....
 
 Now having access to the port-mapped registers we can poke the device in some way and check if it reacts like it is expected to. If it does not then there is probably some other device or no device at all at this address. 
 
 Normally drivers do not set up the interrupt handlers until the attach routine. Instead they do probes in the polling mode using the `DELAY()` function for timeout. The probe routine must never hang forever, all the waits for the device must be done with timeouts. If the device does not respond within the time it is probably broken or misconfigured and the driver must return error. When determining the timeout interval give the device some extra time to be on the safe side: although `DELAY()` is supposed to delay for the same amount of time on any machine it has some margin of error, depending on the exact CPU. 
 
 If the probe routine really wants to check that the interrupts really work it may configure and probe the interrupts too. But that is not recommended. 
 
 [.programlisting]
 ....
 
           /* implemented in some very device-specific way */
           if(error = xxx_probe_ports(sc))
               goto bad; /* will deallocate the resources before returning */
 ....
 
 The function `xxx_probe_ports()` may also set the device description depending on the exact model of device it discovers. But if there is only one supported device model this can be as well done in a hardcoded way. Of course, for the PnP devices the PnP support sets the description from the table automatically. 
 
 [.programlisting]
 ....
           if(pnperror)
               device_set_desc(dev, "Our device model 1234");
 ....
 
 Then the probe routine should either discover the ranges of all the resources by reading the device configuration registers or make sure that they were set explicitly by the user. We will consider it with an example of on-board memory. The probe routine should be as non-intrusive as possible, so allocation and check of functionality of the rest of resources (besides the ports) would be better left to the attach routine. 
 
 The memory address may be specified in the kernel configuration file or on some devices it may be pre-configured in non-volatile configuration registers. If both sources are available and different, which one should be used? Probably if the user bothered to set the address explicitly in the kernel configuration file they know what they are doing and this one should take precedence. An example of implementation could be: 
 
 [.programlisting]
 ....
 
           /* try to find out the config address first */
           sc->mem0_p = bus_get_resource_start(dev, SYS_RES_MEMORY, 0 /*rid*/);
           if(sc->mem0_p == 0) { /* nope, not specified by user */
               sc->mem0_p = xxx_read_mem0_from_device_config(sc);
 
           if(sc->mem0_p == 0)
                   /* can't get it from device config registers either */
                   goto bad;
           } else {
               if(xxx_set_mem0_address_on_device(sc) < 0)
                   goto bad; /* device does not support that address */
           }
 
           /* just like the port, set the memory size,
            * for some devices the memory size would not be constant
            * but should be read from the device configuration registers instead
            * to accommodate different models of devices. Another option would
            * be to let the user set the memory size as "msize" configuration
            * resource which will be automatically handled by the ISA bus.
            */
            if(pnperror) { /* only for non-PnP devices */
               sc->mem0_size = bus_get_resource_count(dev, SYS_RES_MEMORY, 0 /*rid*/);
               if(sc->mem0_size == 0) /* not specified by user */
                   sc->mem0_size = xxx_read_mem0_size_from_device_config(sc);
 
               if(sc->mem0_size == 0) {
                   /* suppose this is a very old model of device without
                    * auto-configuration features and the user gave no preference,
                    * so assume the minimalistic case
                    * (of course, the real value will vary with the driver)
                    */
                   sc->mem0_size = 8*1024;
               }
 
               if(xxx_set_mem0_size_on_device(sc) < 0)
                   goto bad; /* device does not support that size */
 
               if(bus_set_resource(dev, SYS_RES_MEMORY, /*rid*/0,
                       sc->mem0_p, sc->mem0_size)<0)
                   goto bad;
           } else {
               sc->mem0_size = bus_get_resource_count(dev, SYS_RES_MEMORY, 0 /*rid*/);
           }
 ....
 
 Resources for IRQ and DRQ are easy to check by analogy. 
 
 If all went well then release all the resources and return success. 
 
 [.programlisting]
 ....
           xxx_free_resources(sc);
           return 0;
 ....
 
 Finally, handle the troublesome situations. All the resources should be deallocated before returning. We make use of the fact that before the structure softc is passed to us it gets zeroed out, so we can find out if some resource was allocated: then its descriptor is non-zero. 
 
 [.programlisting]
 ....
           bad:
 
           xxx_free_resources(sc);
           if(error)
                 return error;
           else /* exact error is unknown */
               return ENXIO;
 ....
 
 That would be all for the probe routine. Freeing of resources is done from multiple places, so it is moved to a function which may look like: 
 
 [.programlisting]
 ....
 static void
            xxx_free_resources(sc)
               struct xxx_softc *sc;
           {
               /* check every resource and free if not zero */
 
               /* interrupt handler */
               if(sc->intr_r) {
                   bus_teardown_intr(sc->dev, sc->intr_r, sc->intr_cookie);
                   bus_release_resource(sc->dev, SYS_RES_IRQ, sc->intr_rid,
                       sc->intr_r);
                   sc->intr_r = 0;
               }
 
               /* all kinds of memory maps we could have allocated */
               if(sc->data_p) {
                   bus_dmamap_unload(sc->data_tag, sc->data_map);
                   sc->data_p = 0;
               }
                if(sc->data) { /* sc->data_map may be legitimately equal to 0 */
                   /* the map will also be freed */
                   bus_dmamem_free(sc->data_tag, sc->data, sc->data_map);
                   sc->data = 0;
               }
               if(sc->data_tag) {
                   bus_dma_tag_destroy(sc->data_tag);
                   sc->data_tag = 0;
               }
 
               ... free other maps and tags if we have them ...
 
               if(sc->parent_tag) {
                   bus_dma_tag_destroy(sc->parent_tag);
                   sc->parent_tag = 0;
               }
 
               /* release all the bus resources */
               if(sc->mem0_r) {
                   bus_release_resource(sc->dev, SYS_RES_MEMORY, sc->mem0_rid,
                       sc->mem0_r);
                   sc->mem0_r = 0;
               }
               ...
               if(sc->port0_r) {
                   bus_release_resource(sc->dev, SYS_RES_IOPORT, sc->port0_rid,
                       sc->port0_r);
                   sc->port0_r = 0;
               }
           }
 ....
 
 [[isa-driver-attach]]
 == xxx_isa_attach
 
 The attach routine actually connects the driver to the system if the probe routine returned success and the system had chosen to attach that driver. If the probe routine returned 0 then the attach routine may expect to receive the device structure softc intact, as it was set by the probe routine. Also if the probe routine returns 0 it may expect that the attach routine for this device shall be called at some point in the future. If the probe routine returns a negative value then the driver may make none of these assumptions. 
 
 The attach routine returns 0 if it completed successfully or error code otherwise. 
 
 The attach routine starts just like the probe routine, with getting some frequently used data into more accessible variables. 
 
 [.programlisting]
 ....
           struct xxx_softc *sc = device_get_softc(dev);
           int unit = device_get_unit(dev);
           int error = 0;
 ....
 
 Then allocate and activate all the necessary resources. As normally the port range will be released before returning from probe, it has to be allocated again. We expect that the probe routine had properly set all the resource ranges, as well as saved them in the structure softc. If the probe routine had left some resource allocated then it does not need to be allocated again (which would be considered an error). 
 
 [.programlisting]
 ....
           sc->port0_rid = 0;
           sc->port0_r = bus_alloc_resource(dev, SYS_RES_IOPORT,  &sc->port0_rid,
               /*start*/ 0, /*end*/ ~0, /*count*/ 0, RF_ACTIVE);
 
           if(sc->port0_r == NULL)
                return ENXIO;
 
           /* on-board memory */
           sc->mem0_rid = 0;
           sc->mem0_r = bus_alloc_resource(dev, SYS_RES_MEMORY,  &sc->mem0_rid,
               /*start*/ 0, /*end*/ ~0, /*count*/ 0, RF_ACTIVE);
 
           if(sc->mem0_r == NULL)
                 goto bad;
 
           /* get its virtual address */
           sc->mem0_v = rman_get_virtual(sc->mem0_r);
 ....
 
 The DMA request channel (DRQ) is allocated likewise. To initialize it use functions of the `isa_dma*()` family. For example: 
 
 `isa_dmacascade(sc->drq0);`
 
 The interrupt request line (IRQ) is a bit special. Besides allocation the driver's interrupt handler should be associated with it. Historically in the old ISA drivers the argument passed by the system to the interrupt handler was the device unit number. But in modern drivers the convention suggests passing the pointer to structure softc. The important reason is that when the structures softc are allocated dynamically then getting the unit number from softc is easy while getting softc from the unit number is difficult. Also this convention makes the drivers for different buses look more uniform and allows them to share the code: each bus gets its own probe, attach, detach and other bus-specific routines while the bulk of the driver code may be shared among them. 
 
 [.programlisting]
 ....
 
           sc->intr_rid = 0;
           sc->intr_r = bus_alloc_resource(dev, SYS_RES_MEMORY,  &sc->intr_rid,
                 /*start*/ 0, /*end*/ ~0, /*count*/ 0, RF_ACTIVE);
 
           if(sc->intr_r == NULL)
               goto bad;
 
           /*
            * XXX_INTR_TYPE is supposed to be defined depending on the type of
            * the driver, for example as INTR_TYPE_CAM for a CAM driver
            */
           error = bus_setup_intr(dev, sc->intr_r, XXX_INTR_TYPE,
               (driver_intr_t *) xxx_intr, (void *) sc, &sc->intr_cookie);
           if(error)
               goto bad;
 ....
 
 If the device needs to make DMA to the main memory then this memory should be allocated like described before: 
 
 [.programlisting]
 ....
           error=bus_dma_tag_create(NULL, /*alignment*/ 4,
               /*boundary*/ 0, /*lowaddr*/ BUS_SPACE_MAXADDR_24BIT,
               /*highaddr*/ BUS_SPACE_MAXADDR, /*filter*/ NULL, /*filterarg*/ NULL,
               /*maxsize*/ BUS_SPACE_MAXSIZE_24BIT,
               /*nsegments*/ BUS_SPACE_UNRESTRICTED,
               /*maxsegsz*/ BUS_SPACE_MAXSIZE_24BIT, /*flags*/ 0,
               &sc->parent_tag);
           if(error)
               goto bad;
 
           /* many things get inherited from the parent tag
            * sc->data is supposed to point to the structure with the shared data,
            * for example for a ring buffer it could be:
            * struct {
            *   u_short rd_pos;
            *   u_short wr_pos;
            *   char    bf[XXX_RING_BUFFER_SIZE]
            * } *data;
            */
           error=bus_dma_tag_create(sc->parent_tag, 1,
               0, BUS_SPACE_MAXADDR, 0, /*filter*/ NULL, /*filterarg*/ NULL,
               /*maxsize*/ sizeof(* sc->data), /*nsegments*/ 1,
               /*maxsegsz*/ sizeof(* sc->data), /*flags*/ 0,
               &sc->data_tag);
           if(error)
               goto bad;
 
           error = bus_dmamem_alloc(sc->data_tag, &sc->data, /* flags*/ 0,
               &sc->data_map);
           if(error)
                goto bad;
 
           /* xxx_alloc_callback() just saves the physical address at
            * the pointer passed as its argument, in this case &sc->data_p.
            * See details in the section on bus memory mapping.
            * It can be implemented like:
            *
            * static void
            * xxx_alloc_callback(void *arg, bus_dma_segment_t *seg,
            *     int nseg, int error)
            * {
            *    *(bus_addr_t *)arg = seg[0].ds_addr;
            * }
            */
           bus_dmamap_load(sc->data_tag, sc->data_map, (void *)sc->data,
               sizeof (* sc->data), xxx_alloc_callback, (void *) &sc->data_p,
               /*flags*/0);
 ....
 
 After all the necessary resources are allocated the device should be initialized. The initialization may include testing that all the expected features are functional.
 
 [.programlisting]
 ....
           if(xxx_initialize(sc) < 0)
                goto bad;
 ....
 
 The bus subsystem will automatically print on the console the device description set by probe. But if the driver wants to print some extra information about the device it may do so, for example:
 
 [.programlisting]
 ....
 
         device_printf(dev, "has on-card FIFO buffer of %d bytes\n", sc->fifosize);
 ....
 
 If the initialization routine experiences any problems then printing messages about them before returning error is also recommended.
 
 The final step of the attach routine is attaching the device to its functional subsystem in the kernel. The exact way to do it depends on the type of the driver: a character device, a block device, a network device, a CAM SCSI bus device and so on.
 
 If all went well then return success.
 
 [.programlisting]
 ....
           error = xxx_attach_subsystem(sc);
           if(error)
               goto bad;
 
           return 0;
 ....
 
 Finally, handle the troublesome situations. All the resources should be deallocated before returning an error. We make use of the fact that before the structure softc is passed to us it gets zeroed out, so we can find out if some resource was allocated: then its descriptor is non-zero.
 
 [.programlisting]
 ....
           bad:
 
           xxx_free_resources(sc);
           if(error)
               return error;
           else /* exact error is unknown */
               return ENXIO;
 ....
 
 That would be all for the attach routine.
 
 [[isa-driver-detach]]
 == xxx_isa_detach
 
 If this function is present in the driver and the driver is compiled as a loadable module then the driver gets the ability to be unloaded. This is an important feature if the hardware supports hot plug. But the ISA bus does not support hot plug, so this feature is not particularly important for the ISA devices. The ability to unload a driver may be useful when debugging it, but in many cases installation of the new version of the driver would be required only after the old version somehow wedges the system and a reboot will be needed anyway, so the efforts spent on writing the detach routine may not be worth it. Another argument that unloading would allow upgrading the drivers on a production machine seems to be mostly theoretical. Installing a new version of a driver is a dangerous operation which should never be performed on a production machine (and which is not permitted when the system is running in secure mode). Still, the detach routine may be provided for the sake of completeness. 
 
 The detach routine returns 0 if the driver was successfully detached or the error code otherwise. 
 
 The logic of detach is a mirror of the attach. The first thing to do is to detach the driver from its kernel subsystem. If the device is currently open then the driver has two choices: refuse to be detached or forcibly close and proceed with detach. The choice used depends on the ability of the particular kernel subsystem to do a forced close and on the preferences of the driver's author. Generally the forced close seems to be the preferred alternative. 
 
 [.programlisting]
 ....
           struct xxx_softc *sc = device_get_softc(dev);
           int error;
 
           error = xxx_detach_subsystem(sc);
           if(error)
               return error;
 ....
 
 Next the driver may want to reset the hardware to some consistent state. That includes stopping any ongoing transfers, disabling the DMA channels and interrupts to avoid memory corruption by the device. For most of the drivers this is exactly what the shutdown routine does, so if it is included in the driver we can just call it. 
 
 `xxx_isa_shutdown(dev);`
 
 And finally release all the resources and return success.
 
 [.programlisting]
 ....
           xxx_free_resources(sc);
           return 0;
 ....
 
 [[isa-driver-shutdown]]
 == xxx_isa_shutdown
 
 This routine is called when the system is about to be shut down. It is expected to bring the hardware to some consistent state. For most of the ISA devices no special action is required, so the function is not really necessary because the device will be re-initialized on reboot anyway. But some devices have to be shut down with a special procedure, to make sure that they will be properly detected after soft reboot (this is especially true for many devices with proprietary identification protocols). In any case disabling DMA and interrupts in the device registers and stopping any ongoing transfers is a good idea. The exact action depends on the hardware, so we do not consider it here in any detail. 
 
 [[isa-driver-intr]]
 == xxx_intr
 
 The interrupt handler is called when an interrupt is received which may be from this particular device. The ISA bus does not support interrupt sharing (except in some special cases) so in practice if the interrupt handler is called then the interrupt almost for sure came from its device. Still, the interrupt handler must poll the device registers and make sure that the interrupt was generated by its device. If not it should just return. 
 
 The old convention for the ISA drivers was getting the device unit number as an argument. This is obsolete, and the new drivers receive whatever argument was specified for them in the attach routine when calling `bus_setup_intr()`. By the new convention it should be the pointer to the structure softc. So the interrupt handler commonly starts as: 
 
 [.programlisting]
 ....
 
           static void
           xxx_intr(struct xxx_softc *sc)
           {
 ....
 
 It runs at the interrupt priority level specified by the interrupt type parameter of `bus_setup_intr()`. That means that all the other interrupts of the same type as well as all the software interrupts are disabled. 
 
 To avoid races it is commonly written as a loop: 
 
 [.programlisting]
 ....
 
           while(xxx_interrupt_pending(sc)) {
               xxx_process_interrupt(sc);
               xxx_acknowledge_interrupt(sc);
           }
 ....
 
 The interrupt handler has to acknowledge interrupt to the device only but not to the interrupt controller, the system takes care of the latter.
diff --git a/documentation/content/en/books/arch-handbook/jail/_index.adoc b/documentation/content/en/books/arch-handbook/jail/_index.adoc
index d5556b6957..2591a46629 100644
--- a/documentation/content/en/books/arch-handbook/jail/_index.adoc
+++ b/documentation/content/en/books/arch-handbook/jail/_index.adoc
@@ -1,512 +1,512 @@
 ---
 title: Chapter 4. The Jail Subsystem
 prev: books/arch-handbook/kobj
 next: books/arch-handbook/sysinit
 description: The Jail Subsystem
 tags: ["jail", "architecture", "networking", "kernel"]
 ---
 
 [[jail]]
 = The Jail Subsystem
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 4
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 On most UNIX(R) systems, `root` has omnipotent power. This promotes insecurity. If an attacker gained `root` on a system, he would have every function at his fingertips. In FreeBSD there are sysctls which dilute the power of `root`, in order to minimize the damage caused by an attacker. Specifically, one of these functions is called `secure levels`. Similarly, another function which is present from FreeBSD 4.0 and onward, is a utility called man:jail[8]. Jail chroots an environment and sets certain restrictions on processes which are forked within the jail. For example, a jailed process cannot affect processes outside the jail, utilize certain system calls, or inflict any damage on the host environment.
 
 Jail is becoming the new security model. People are running potentially vulnerable servers such as Apache, BIND, and sendmail within jails, so that if an attacker gains `root` within the jail, it is only an annoyance, and not a devastation. This article mainly focuses on the internals (source code) of jail. For information on how to set up a jail see the link:{handbook}#jails/[handbook entry on jails].
 
 [[jail-arch]]
 == Architecture
 
 Jail consists of two realms: the userland program, man:jail[8], and the code implemented within the kernel: the man:jail[2] system call and associated restrictions. I will be discussing the userland program and then how jail is implemented within the kernel.
 
 === Userland Code
 
 The source for the userland jail is located in [.filename]#/usr/src/usr.sbin/jail#, consisting of one file, [.filename]#jail.c#. The program takes these arguments: the path of the jail, hostname, IP address, and the command to be executed.
 
 ==== Data Structures
 
 In [.filename]#jail.c#, the first thing I would note is the declaration of an important structure `struct jail j;` which was included from [.filename]#/usr/include/sys/jail.h#.
 
 The definition of the `jail` structure is:
 
 [.programlisting]
 ....
 /usr/include/sys/jail.h:
 
 struct jail {
         u_int32_t       version;
         char            *path;
         char            *hostname;
         u_int32_t       ip_number;
 };
 ....
 
 As you can see, there is an entry for each of the arguments passed to the man:jail[8] program, and indeed, they are set during its execution.
 
 [.programlisting]
 ....
 /usr/src/usr.sbin/jail/jail.c
 char path[PATH_MAX];
 ...
 if (realpath(argv[0], path) == NULL)
     err(1, "realpath: %s", argv[0]);
 if (chdir(path) != 0)
     err(1, "chdir: %s", path);
 memset(&j, 0, sizeof(j));
 j.version = 0;
 j.path = path;
 j.hostname = argv[1];
 ....
 
 ==== Networking
 
 One of the arguments passed to the man:jail[8] program is an IP address with which the jail can be accessed over the network. man:jail[8] translates the IP address given into host byte order and then stores it in `j` (the `jail` structure).
 
 [.programlisting]
 ....
 /usr/src/usr.sbin/jail/jail.c:
 struct in_addr in;
 ...
 if (inet_aton(argv[2], &in) == 0)
     errx(1, "Could not make sense of ip-number: %s", argv[2]);
 j.ip_number = ntohl(in.s_addr);
 ....
 
 The man:inet_aton[3] function "interprets the specified character string as an Internet address, placing the address into the structure provided." The `ip_number` member in the `jail` structure is set only when the IP address placed onto the `in` structure by man:inet_aton[3] is translated into host byte order by man:ntohl[3].
 
 ==== Jailing the Process
 
 Finally, the userland program jails the process. Jail now becomes an imprisoned process itself and then executes the command given using man:execv[3].
 
 [.programlisting]
 ....
 /usr/src/usr.sbin/jail/jail.c
 i = jail(&j);
 ...
 if (execv(argv[3], argv + 3) != 0)
     err(1, "execv: %s", argv[3]);
 ....
 
 As you can see, the `jail()` function is called, and its argument is the `jail` structure which has been filled with the arguments given to the program. Finally, the program you specify is executed. I will now discuss how jail is implemented within the kernel.
 
 === Kernel Space
 
 We will now be looking at the file [.filename]#/usr/src/sys/kern/kern_jail.c#. This is the file where the man:jail[2] system call, appropriate sysctls, and networking functions are defined.
 
 ==== Sysctls
 
 In [.filename]#kern_jail.c#, the following sysctls are defined:
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c:
 int     jail_set_hostname_allowed = 1;
 SYSCTL_INT(_security_jail, OID_AUTO, set_hostname_allowed, CTLFLAG_RW,
     &jail_set_hostname_allowed, 0,
     "Processes in jail can set their hostnames");
 
 int     jail_socket_unixiproute_only = 1;
 SYSCTL_INT(_security_jail, OID_AUTO, socket_unixiproute_only, CTLFLAG_RW,
     &jail_socket_unixiproute_only, 0,
     "Processes in jail are limited to creating UNIX/IPv4/route sockets only");
 
 int     jail_sysvipc_allowed = 0;
 SYSCTL_INT(_security_jail, OID_AUTO, sysvipc_allowed, CTLFLAG_RW,
     &jail_sysvipc_allowed, 0,
     "Processes in jail can use System V IPC primitives");
 
 static int jail_enforce_statfs = 2;
 SYSCTL_INT(_security_jail, OID_AUTO, enforce_statfs, CTLFLAG_RW,
     &jail_enforce_statfs, 0,
     "Processes in jail cannot see all mounted file systems");
 
 int    jail_allow_raw_sockets = 0;
 SYSCTL_INT(_security_jail, OID_AUTO, allow_raw_sockets, CTLFLAG_RW,
     &jail_allow_raw_sockets, 0,
     "Prison root can create raw sockets");
 
 int    jail_chflags_allowed = 0;
 SYSCTL_INT(_security_jail, OID_AUTO, chflags_allowed, CTLFLAG_RW,
     &jail_chflags_allowed, 0,
     "Processes in jail can alter system file flags");
 
 int     jail_mount_allowed = 0;
 SYSCTL_INT(_security_jail, OID_AUTO, mount_allowed, CTLFLAG_RW,
     &jail_mount_allowed, 0,
     "Processes in jail can mount/unmount jail-friendly file systems");
 ....
 
 Each of these sysctls can be accessed by the user through the man:sysctl[8] program. Throughout the kernel, these specific sysctls are recognized by their name. For example, the name of the first sysctl is `security.jail.set_hostname_allowed`.
 
 ==== man:jail[2] System Call
 
 Like all system calls, the man:jail[2] system call takes two arguments, `struct thread *td` and `struct jail_args *uap`. `td` is a pointer to the `thread` structure which describes the calling thread. In this context, `uap` is a pointer to the structure in which a pointer to the `jail` structure passed by the userland [.filename]#jail.c# is contained. When I described the userland program before, you saw that the man:jail[2] system call was given a `jail` structure as its own argument.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c:
 /*
  * struct jail_args {
  *  struct jail *jail;
  * };
  */
 int
 jail(struct thread *td, struct jail_args *uap)
 ....
 
 Therefore, `uap->jail` can be used to access the `jail` structure which was passed to the system call. Next, the system call copies the `jail` structure into kernel space using the man:copyin[9] function. man:copyin[9] takes three arguments: the address of the data which is to be copied into kernel space, `uap->jail`, where to store it, `j` and the size of the storage. The `jail` structure pointed by `uap->jail` is copied into kernel space and is stored in another `jail` structure, `j`.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c:
 error = copyin(uap->jail, &j, sizeof(j));
 ....
 
 There is another important structure defined in [.filename]#jail.h#. It is the `prison` structure. The `prison` structure is used exclusively within kernel space. Here is the definition of the `prison` structure.
 
 [.programlisting]
 ....
 /usr/include/sys/jail.h:
 struct prison {
         LIST_ENTRY(prison) pr_list;                     /* (a) all prisons */
         int              pr_id;                         /* (c) prison id */
         int              pr_ref;                        /* (p) refcount */
         char             pr_path[MAXPATHLEN];           /* (c) chroot path */
         struct vnode    *pr_root;                       /* (c) vnode to rdir */
         char             pr_host[MAXHOSTNAMELEN];       /* (p) jail hostname */
         u_int32_t        pr_ip;                         /* (c) ip addr host */
         void            *pr_linux;                      /* (p) linux abi */
         int              pr_securelevel;                /* (p) securelevel */
         struct task      pr_task;                       /* (d) destroy task */
         struct mtx       pr_mtx;
       void            **pr_slots;                     /* (p) additional data */
 };
 ....
 
 The man:jail[2] system call then allocates memory for a `prison` structure and copies data between the `jail` and `prison` structure.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c:
 MALLOC(pr, struct prison *, sizeof(*pr), M_PRISON, M_WAITOK | M_ZERO);
 ...
 error = copyinstr(j.path, &pr->pr_path, sizeof(pr->pr_path), 0);
 if (error)
     goto e_killmtx;
 ...
 error = copyinstr(j.hostname, &pr->pr_host, sizeof(pr->pr_host), 0);
 if (error)
      goto e_dropvnref;
 pr->pr_ip = j.ip_number;
 ....
 
 Next, we will discuss another important system call man:jail_attach[2], which implements the function to put a process into the jail.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c:
 /*
  * struct jail_attach_args {
  *      int jid;
  * };
  */
 int
 jail_attach(struct thread *td, struct jail_attach_args *uap)
 ....
 
 This system call makes the changes that can distinguish a jailed process from those unjailed ones. To understand what man:jail_attach[2] does for us, certain background information is needed.
 
 On FreeBSD, each kernel visible thread is identified by its `thread` structure, while the processes are described by their `proc` structures. You can find the definitions of the `thread` and `proc` structure in [.filename]#/usr/include/sys/proc.h#. For example, the `td` argument in any system call is actually a pointer to the calling thread's `thread` structure, as stated before. The `td_proc` member in the `thread` structure pointed by `td` is a pointer to the `proc` structure which represents the process that contains the thread represented by `td`. The `proc` structure contains members which can describe the owner's identity(`p_ucred`), the process resource limits(`p_limit`), and so on. In the `ucred` structure pointed by `p_ucred` member in the `proc` structure, there is a pointer to the `prison` structure(`cr_prison`).
 
 [.programlisting]
 ....
 /usr/include/sys/proc.h:
 struct thread {
     ...
     struct proc *td_proc;
     ...
 };
 struct proc {
     ...
     struct ucred *p_ucred;
     ...
 };
 /usr/include/sys/ucred.h
 struct ucred {
     ...
     struct prison *cr_prison;
     ...
 };
 ....
 
 In [.filename]#kern_jail.c#, the function `jail()` then calls function `jail_attach()` with a given `jid`. And `jail_attach()` calls function `change_root()` to change the root directory of the calling process. The `jail_attach()` then creates a new `ucred` structure, and attaches the newly created `ucred` structure to the calling process after it has successfully attached the `prison` structure to the `ucred` structure. From then on, the calling process is recognized as jailed. When the kernel routine `jailed()` is called in the kernel with the newly created `ucred` structure as its argument, it returns 1 to tell that the credential is connected with a jail. The public ancestor process of all the process forked within the jail, is the process which runs man:jail[8], as it calls the man:jail[2] system call. When a program is executed through man:execve[2], it inherits the jailed property of its parent's `ucred` structure, therefore it has a jailed `ucred` structure.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c
 int
 jail(struct thread *td, struct jail_args *uap)
 {
 ...
     struct jail_attach_args jaa;
 ...
     error = jail_attach(td, &jaa);
     if (error)
         goto e_dropprref;
 ...
 }
 
 int
 jail_attach(struct thread *td, struct jail_attach_args *uap)
 {
     struct proc *p;
     struct ucred *newcred, *oldcred;
     struct prison *pr;
 ...
     p = td->td_proc;
 ...
     pr = prison_find(uap->jid);
 ...
     change_root(pr->pr_root, td);
 ...
     newcred->cr_prison = pr;
     p->p_ucred = newcred;
 ...
 }
 ....
 
 When a process is forked from its parent process, the man:fork[2] system call uses `crhold()` to maintain the credential for the newly forked process. It inherently keep the newly forked child's credential consistent with its parent, so the child process is also jailed.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_fork.c:
 p2->p_ucred = crhold(td->td_ucred);
 ...
 td2->td_ucred = crhold(p2->p_ucred);
 ....
 
 [[jail-restrictions]]
 == Restrictions
 
 Throughout the kernel there are access restrictions relating to jailed processes. Usually, these restrictions only check whether the process is jailed, and if so, returns an error. For example:
 
 [.programlisting]
 ....
 if (jailed(td->td_ucred))
     return (EPERM);
 ....
 
 === SysV IPC
 
 System V IPC is based on messages. Processes can send each other these messages which tell them how to act. The functions which deal with messages are: man:msgctl[3], man:msgget[3], man:msgsnd[3] and man:msgrcv[3]. Earlier, I mentioned that there were certain sysctls you could turn on or off in order to affect the behavior of jail. One of these sysctls was `security.jail.sysvipc_allowed`. By default, this sysctl is set to 0. If it were set to 1, it would defeat the whole purpose of having a jail; privileged users from the jail would be able to affect processes outside the jailed environment. The difference between a message and a signal is that the message only consists of the signal number.
 
 [.filename]#/usr/src/sys/kern/sysv_msg.c#:
 
 * `msgget(key, msgflg)`: `msgget` returns (and possibly creates) a message descriptor that designates a message queue for use in other functions.
 * `msgctl(msgid, cmd, buf)`: Using this function, a process can query the status of a message descriptor.
 * `msgsnd(msgid, msgp, msgsz, msgflg)`: `msgsnd` sends a message to a process.
 * `msgrcv(msgid, msgp, msgsz, msgtyp, msgflg)`: a process receives messages using this function
 
 In each of the system calls corresponding to these functions, there is this conditional:
 
 [.programlisting]
 ....
 /usr/src/sys/kern/sysv_msg.c:
 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
     return (ENOSYS);
 ....
 
 Semaphore system calls allow processes to synchronize execution by doing a set of operations atomically on a set of semaphores. Basically semaphores provide another way for processes lock resources. However, process waiting on a semaphore, that is being used, will sleep until the resources are relinquished. The following semaphore system calls are blocked inside a jail: man:semget[2], man:semctl[2] and man:semop[2].
 
 [.filename]#/usr/src/sys/kern/sysv_sem.c#:
 
 * `semctl(semid, semnum, cmd, ...)`: `semctl` does the specified `cmd` on the semaphore queue indicated by `semid`.
 * `semget(key, nsems, flag)`: `semget` creates an array of semaphores, corresponding to `key`.
-+ 
++
 `key and flag take on the same meaning as they do in msgget.`
 * `semop(semid, array, nops)`: `semop` performs a group of operations indicated by `array`, to the set of semaphores identified by `semid`.
 
 System V IPC allows for processes to share memory. Processes can communicate directly with each other by sharing parts of their virtual address space and then reading and writing data stored in the shared memory. These system calls are blocked within a jailed environment: man:shmdt[2], man:shmat[2], man:shmctl[2] and man:shmget[2].
 
 [.filename]#/usr/src/sys/kern/sysv_shm.c#:
 
 * `shmctl(shmid, cmd, buf)`: `shmctl` does various control operations on the shared memory region identified by `shmid`.
 * `shmget(key, size, flag)`: `shmget` accesses or creates a shared memory region of `size` bytes.
 * `shmat(shmid, addr, flag)`: `shmat` attaches a shared memory region identified by `shmid` to the address space of a process.
 * `shmdt(addr)`: `shmdt` detaches the shared memory region previously attached at `addr`.
 
 === Sockets
 
 Jail treats the man:socket[2] system call and related lower-level socket functions in a special manner. In order to determine whether a certain socket is allowed to be created, it first checks to see if the sysctl `security.jail.socket_unixiproute_only` is set. If set, sockets are only allowed to be created if the family specified is either `PF_LOCAL`, `PF_INET` or `PF_ROUTE`. Otherwise, it returns an error.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/uipc_socket.c:
 int
 socreate(int dom, struct socket **aso, int type, int proto,
     struct ucred *cred, struct thread *td)
 {
     struct protosw *prp;
 ...
     if (jailed(cred) && jail_socket_unixiproute_only &&
         prp->pr_domain->dom_family != PF_LOCAL &&
         prp->pr_domain->dom_family != PF_INET &&
         prp->pr_domain->dom_family != PF_ROUTE) {
         return (EPROTONOSUPPORT);
     }
 ...
 }
 ....
 
 === Berkeley Packet Filter
 
 The Berkeley Packet Filter provides a raw interface to data link layers in a protocol independent fashion. BPF is now controlled by the man:devfs[8] whether it can be used in a jailed environment.
 
 === Protocols
 
 There are certain protocols which are very common, such as TCP, UDP, IP and ICMP. IP and ICMP are on the same level: the network layer 2. There are certain precautions which are taken in order to prevent a jailed process from binding a protocol to a certain address only if the `nam` parameter is set. `nam` is a pointer to a `sockaddr` structure, which describes the address on which to bind the service. A more exact definition is that `sockaddr` "may be used as a template for referring to the identifying tag and length of each address". In the function `in_pcbbind_setup()`, `sin` is a pointer to a `sockaddr_in` structure, which contains the port, address, length and domain family of the socket which is to be bound. Basically, this disallows any processes from jail to be able to specify the address that does not belong to the jail in which the calling process exists.
 
 [.programlisting]
 ....
 /usr/src/sys/netinet/in_pcb.c:
 int
 in_pcbbind_setup(struct inpcb *inp, struct sockaddr *nam, in_addr_t *laddrp,
     u_short *lportp, struct ucred *cred)
 {
     ...
     struct sockaddr_in *sin;
     ...
     if (nam) {
         sin = (struct sockaddr_in *)nam;
         ...
         if (sin->sin_addr.s_addr != INADDR_ANY)
             if (prison_ip(cred, 0, &sin->sin_addr.s_addr))
                 return(EINVAL);
         ...
         if (lport) {
             ...
             if (prison && prison_ip(cred, 0, &sin->sin_addr.s_addr))
                 return (EADDRNOTAVAIL);
             ...
         }
     }
     if (lport == 0) {
         ...
         if (laddr.s_addr != INADDR_ANY)
             if (prison_ip(cred, 0, &laddr.s_addr))
                 return (EINVAL);
         ...
     }
 ...
     if (prison_ip(cred, 0, &laddr.s_addr))
         return (EINVAL);
 ...
 }
 ....
 
 You might be wondering what function `prison_ip()` does. `prison_ip()` is given three arguments, a pointer to the credential(represented by `cred`), any flags, and an IP address. It returns 1 if the IP address does NOT belong to the jail or 0 otherwise. As you can see from the code, if it is indeed an IP address not belonging to the jail, the protocol is not allowed to bind to that address.
 
 [.programlisting]
 ....
 /usr/src/sys/kern/kern_jail.c:
 int
 prison_ip(struct ucred *cred, int flag, u_int32_t *ip)
 {
     u_int32_t tmp;
 
     if (!jailed(cred))
         return (0);
     if (flag)
         tmp = *ip;
     else
         tmp = ntohl(*ip);
     if (tmp == INADDR_ANY) {
         if (flag)
             *ip = cred->cr_prison->pr_ip;
         else
             *ip = htonl(cred->cr_prison->pr_ip);
         return (0);
     }
     if (tmp == INADDR_LOOPBACK) {
         if (flag)
             *ip = cred->cr_prison->pr_ip;
         else
             *ip = htonl(cred->cr_prison->pr_ip);
         return (0);
     }
     if (cred->cr_prison->pr_ip != tmp)
         return (1);
     return (0);
 }
 ....
 
 === Filesystem
 
 Even `root` users within the jail are not allowed to unset or modify any file flags, such as immutable, append-only, and undeleteable flags, if the securelevel is greater than 0.
 
 [.programlisting]
 ....
 /usr/src/sys/ufs/ufs/ufs_vnops.c:
 static int
 ufs_setattr(ap)
     ...
 {
     ...
         if (!priv_check_cred(cred, PRIV_VFS_SYSFLAGS, 0)) {
             if (ip->i_flags
                 & (SF_NOUNLINK | SF_IMMUTABLE | SF_APPEND)) {
                     error = securelevel_gt(cred, 0);
                     if (error)
                         return (error);
             }
             ...
         }
 }
 /usr/src/sys/kern/kern_priv.c
 int
 priv_check_cred(struct ucred *cred, int priv, int flags)
 {
     ...
     error = prison_priv_check(cred, priv);
     if (error)
         return (error);
     ...
 }
 /usr/src/sys/kern/kern_jail.c
 int
 prison_priv_check(struct ucred *cred, int priv)
 {
     ...
     switch (priv) {
     ...
     case PRIV_VFS_SYSFLAGS:
         if (jail_chflags_allowed)
             return (0);
         else
             return (EPERM);
     ...
     }
     ...
 }
 ....
diff --git a/documentation/content/en/books/arch-handbook/scsi/_index.adoc b/documentation/content/en/books/arch-handbook/scsi/_index.adoc
index eb2e90015d..684ecd184c 100644
--- a/documentation/content/en/books/arch-handbook/scsi/_index.adoc
+++ b/documentation/content/en/books/arch-handbook/scsi/_index.adoc
@@ -1,1357 +1,1357 @@
 ---
 title: Chapter 12. Common Access Method SCSI Controllers
 prev: books/arch-handbook/pci
 next: books/arch-handbook/usb
 description: Common Access Method SCSI Controllers
 tags: ["SCSI", "Controller", "Architecture"]
 ---
 
 [[scsi]]
 = Common Access Method SCSI Controllers
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 12
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[scsi-synopsis]]
 == Synopsis
 
 This document assumes that the reader has a general understanding of device drivers in FreeBSD and of the SCSI protocol. Much of the information in this document was extracted from the drivers:
 
 * ncr ([.filename]#/sys/pci/ncr.c#) by Wolfgang Stanglmeier and Stefan Esser
 * sym ([.filename]#/sys/dev/sym/sym_hipd.c#) by Gerard Roudier
 * aic7xxx ([.filename]#/sys/dev/aic7xxx/aic7xxx.c#) by Justin T. Gibbs
 
 and from the CAM code itself (by Justin T. Gibbs, see [.filename]#/sys/cam/*#). When some solution looked the most logical and was essentially verbatim extracted from the code by Justin T. Gibbs, I marked it as "recommended".
 
 The document is illustrated with examples in pseudo-code. Although sometimes the examples have many details and look like real code, it is still pseudo-code. It was written to demonstrate the concepts in an understandable way. For a real driver other approaches may be more modular and efficient. It also abstracts from the hardware details, as well as issues that would cloud the demonstrated concepts or that are supposed to be described in the other chapters of the developers handbook. Such details are commonly shown as calls to functions with descriptive names, comments or pseudo-statements. Fortunately real life full-size examples with all the details can be found in the real drivers.
 
 [[scsi-general]]
 == General Architecture
 
 CAM stands for Common Access Method. It is a generic way to address the I/O buses in a SCSI-like way. This allows a separation of the generic device drivers from the drivers controlling the I/O bus: for example the disk driver becomes able to control disks on both SCSI, IDE, and/or any other bus so the disk driver portion does not have to be rewritten (or copied and modified) for every new I/O bus. Thus the two most important active entities are:
 
 * _Peripheral Modules_ - a driver for peripheral devices (disk, tape, CD-ROM, etc.)
 * _SCSI Interface Modules_ (SIM) - a Host Bus Adapter drivers for connecting to an I/O bus such as SCSI or IDE.
 
 A peripheral driver receives requests from the OS, converts them to a sequence of SCSI commands and passes these SCSI commands to a SCSI Interface Module. The SCSI Interface Module is responsible for passing these commands to the actual hardware (or if the actual hardware is not SCSI but, for example, IDE then also converting the SCSI commands to the native commands of the hardware).
 
 As we are interested in writing a SCSI adapter driver here, from this point on we will consider everything from the SIM standpoint.
 
 A typical SIM driver needs to include the following CAM-related header files:
 
 [.programlisting]
 ....
 #include <cam/cam.h>
 #include <cam/cam_ccb.h>
 #include <cam/cam_sim.h>
 #include <cam/cam_xpt_sim.h>
 #include <cam/cam_debug.h>
 #include <cam/scsi/scsi_all.h>
 ....
 
 The first thing each SIM driver must do is register itself with the CAM subsystem. This is done during the driver's `xxx_attach()` function (here and further xxx_ is used to denote the unique driver name prefix). The `xxx_attach()` function itself is called by the system bus auto-configuration code which we do not describe here.
 
 This is achieved in multiple steps: first it is necessary to allocate the queue of requests associated with this SIM:
 
 [.programlisting]
 ....
     struct cam_devq *devq;
 
     if(( devq = cam_simq_alloc(SIZE) )==NULL) {
         error; /* some code to handle the error */
     }
 ....
 
 Here `SIZE` is the size of the queue to be allocated, maximal number of requests it could contain. It is the number of requests that the SIM driver can handle in parallel on one SCSI card. Commonly it can be calculated as:
 
 [.programlisting]
 ....
 SIZE = NUMBER_OF_SUPPORTED_TARGETS * MAX_SIMULTANEOUS_COMMANDS_PER_TARGET
 ....
 
 Next we create a descriptor of our SIM:
 
 [.programlisting]
 ....
     struct cam_sim *sim;
 
     if(( sim = cam_sim_alloc(action_func, poll_func, driver_name,
             softc, unit, mtx, max_dev_transactions,
             max_tagged_dev_transactions, devq) )==NULL) {
         cam_simq_free(devq);
         error; /* some code to handle the error */
     }
 ....
 
 Note that if we are not able to create a SIM descriptor we free the `devq` also because we can do nothing else with it and we want to conserve memory.
 
 If a SCSI card has multiple SCSI buses on it then each bus requires its own `cam_sim` structure.
 
 An interesting question is what to do if a SCSI card has more than one SCSI bus, do we need one `devq` structure per card or per SCSI bus? The answer given in the comments to the CAM code is: either way, as the driver's author prefers.
 
 The arguments are:
 
 * `action_func` - pointer to the driver's `xxx_action` function. 
 +
 [source,c]
 ----
 static void
 		xxx_action
 	       ();
 ----
 * `poll_func` - pointer to the driver's `xxx_poll()`
 +
 [source,c]
 ----
 static void
 		xxx_poll
 	       ();
 ----
 * driver_name - the name of the actual driver, such as "ncr" or "wds".
 * `softc` - pointer to the driver's internal descriptor for this SCSI card. This pointer will be used by the driver in future to get private data.
 * unit - the controller unit number, for example for controller "mps0" this number will be 0
 * mtx - Lock associated with this SIM. For SIMs that don't know about locking, pass in Giant. For SIMs that do, pass in the lock used to guard this SIM's data structures. This lock will be held when xxx_action and xxx_poll are called.
 * max_dev_transactions - maximal number of simultaneous transactions per SCSI target in the non-tagged mode. This value will be almost universally equal to 1, with possible exceptions only for the non-SCSI cards. Also the drivers that hope to take advantage by preparing one transaction while another one is executed may set it to 2 but this does not seem to be worth the complexity.
 * max_tagged_dev_transactions - the same thing, but in the tagged mode. Tags are the SCSI way to initiate multiple transactions on a device: each transaction is assigned a unique tag and the transaction is sent to the device. When the device completes some transaction it sends back the result together with the tag so that the SCSI adapter (and the driver) can tell which transaction was completed. This argument is also known as the maximal tag depth. It depends on the abilities of the SCSI adapter.
 
 Finally we register the SCSI buses associated with our SCSI adapter:
 
 [.programlisting]
 ....
     if(xpt_bus_register(sim, softc, bus_number) != CAM_SUCCESS) {
         cam_sim_free(sim, /*free_devq*/ TRUE);
         error; /* some code to handle the error */
     }
 ....
 
 If there is one `devq` structure per SCSI bus (i.e., we consider a card with multiple buses as multiple cards with one bus each) then the bus number will always be 0, otherwise each bus on the SCSI card should be get a distinct number. Each bus needs its own separate structure cam_sim.
 
 After that our controller is completely hooked to the CAM system. The value of `devq` can be discarded now: sim will be passed as an argument in all further calls from CAM and devq can be derived from it.
 
 CAM provides the framework for such asynchronous events. Some events originate from the lower levels (the SIM drivers), some events originate from the peripheral drivers, some events originate from the CAM subsystem itself. Any driver can register callbacks for some types of the asynchronous events, so that it would be notified if these events occur.
 
 A typical example of such an event is a device reset. Each transaction and event identifies the devices to which it applies by the means of "path". The target-specific events normally occur during a transaction with this device. So the path from that transaction may be re-used to report this event (this is safe because the event path is copied in the event reporting routine but not deallocated nor passed anywhere further). Also it is safe to allocate paths dynamically at any time including the interrupt routines, although that incurs certain overhead, and a possible problem with this approach is that there may be no free memory at that time. For a bus reset event we need to define a wildcard path including all devices on the bus. So we can create the path for the future bus reset events in advance and avoid problems with the future memory shortage:
 
 [.programlisting]
 ....
     struct cam_path *path;
 
     if(xpt_create_path(&path, /*periph*/NULL,
                 cam_sim_path(sim), CAM_TARGET_WILDCARD,
                 CAM_LUN_WILDCARD) != CAM_REQ_CMP) {
         xpt_bus_deregister(cam_sim_path(sim));
         cam_sim_free(sim, /*free_devq*/TRUE);
         error; /* some code to handle the error */
     }
 
     softc->wpath = path;
     softc->sim = sim;
 ....
 
 As you can see the path includes:
 
 * ID of the peripheral driver (NULL here because we have none)
 * ID of the SIM driver (`cam_sim_path(sim)`)
 * SCSI target number of the device (CAM_TARGET_WILDCARD means "all devices")
 * SCSI LUN number of the subdevice (CAM_LUN_WILDCARD means "all LUNs")
 
 If the driver can not allocate this path it will not be able to work normally, so in that case we dismantle that SCSI bus.
 
 And we save the path pointer in the `softc` structure for future use. After that we save the value of sim (or we can also discard it on the exit from `xxx_probe()` if we wish).
 
 That is all for a minimalistic initialization. To do things right there is one more issue left.
 
 For a SIM driver there is one particularly interesting event: when a target device is considered lost. In this case resetting the SCSI negotiations with this device may be a good idea. So we register a callback for this event with CAM. The request is passed to CAM by requesting CAM action on a CAM control block for this type of request:
 
 [.programlisting]
 ....
     struct ccb_setasync csa;
 
     xpt_setup_ccb(&csa.ccb_h, path, /*priority*/5);
     csa.ccb_h.func_code = XPT_SASYNC_CB;
     csa.event_enable = AC_LOST_DEVICE;
     csa.callback = xxx_async;
     csa.callback_arg = sim;
     xpt_action((union ccb *)&csa);
 ....
 
 Now we take a look at the `xxx_action()` and `xxx_poll()` driver entry points.
 
 [source,c]
 ----
 static void
 	    xxx_action
 	   ();
 ----
 
 Do some action on request of the CAM subsystem. Sim describes the SIM for the request, CCB is the request itself. CCB stands for "CAM Control Block". It is a union of many specific instances, each describing arguments for some type of transactions. All of these instances share the CCB header where the common part of arguments is stored.
 
 CAM supports the SCSI controllers working in both initiator ("normal") mode and target (simulating a SCSI device) mode. Here we only consider the part relevant to the initiator mode.
 
 There are a few function and macros (in other words, methods) defined to access the public data in the struct sim:
 
 * `cam_sim_path(sim)` - the path ID (see above)
 * `cam_sim_name(sim)` - the name of the sim
 * `cam_sim_softc(sim)` - the pointer to the softc (driver private data) structure
 * `cam_sim_unit(sim)` - the unit number
 * `cam_sim_bus(sim)` - the bus ID
 
 To identify the device, `xxx_action()` can get the unit number and pointer to its structure softc using these functions.
 
 The type of request is stored in `ccb->ccb_h.func_code`. So generally `xxx_action()` consists of a big switch:
 
 [.programlisting]
 ....
     struct xxx_softc *softc = (struct xxx_softc *) cam_sim_softc(sim);
     struct ccb_hdr *ccb_h = &ccb->ccb_h;
     int unit = cam_sim_unit(sim);
     int bus = cam_sim_bus(sim);
 
     switch(ccb_h->func_code) {
     case ...:
         ...
     default:
         ccb_h->status = CAM_REQ_INVALID;
         xpt_done(ccb);
         break;
     }
 ....
 
 As can be seen from the default case (if an unknown command was received) the return code of the command is set into `ccb->ccb_h.status` and the completed CCB is returned back to CAM by calling `xpt_done(ccb)`.
 
 `xpt_done()` does not have to be called from `xxx_action()`: For example an I/O request may be enqueued inside the SIM driver and/or its SCSI controller. Then when the device would post an interrupt signaling that the processing of this request is complete `xpt_done()` may be called from the interrupt handling routine.
 
 Actually, the CCB status is not only assigned as a return code but a CCB has some status all the time. Before CCB is passed to the `xxx_action()` routine it gets the status CCB_REQ_INPROG meaning that it is in progress. There are a surprising number of status values defined in [.filename]#/sys/cam/cam.h# which should be able to represent the status of a request in great detail. More interesting yet, the status is in fact a "bitwise or" of an enumerated status value (the lower 6 bits) and possible additional flag-like bits (the upper bits). The enumerated values will be discussed later in more detail. The summary of them can be found in the Errors Summary section. The possible status flags are:
 
 * _CAM_DEV_QFRZN_ - if the SIM driver gets a serious error (for example, the device does not respond to the selection or breaks the SCSI protocol) when processing a CCB it should freeze the request queue by calling `xpt_freeze_simq()`, return the other enqueued but not processed yet CCBs for this device back to the CAM queue, then set this flag for the troublesome CCB and call `xpt_done()`. This flag causes the CAM subsystem to unfreeze the queue after it handles the error.
 * _CAM_AUTOSNS_VALID_ - if the device returned an error condition and the flag CAM_DIS_AUTOSENSE is not set in CCB the SIM driver must execute the REQUEST SENSE command automatically to extract the sense (extended error information) data from the device. If this attempt was successful the sense data should be saved in the CCB and this flag set.
 * _CAM_RELEASE_SIMQ_ - like CAM_DEV_QFRZN but used in case there is some problem (or resource shortage) with the SCSI controller itself. Then all the future requests to the controller should be stopped by `xpt_freeze_simq()`. The controller queue will be restarted after the SIM driver overcomes the shortage and informs CAM by returning some CCB with this flag set.
 * _CAM_SIM_QUEUED_ - when SIM puts a CCB into its request queue this flag should be set (and removed when this CCB gets dequeued before being returned back to CAM). This flag is not used anywhere in the CAM code now, so its purpose is purely diagnostic.
 * _CAM_QOS_VALID_ - The QOS data is now valid.
 
 The function `xxx_action()` is not allowed to sleep, so all the synchronization for resource access must be done using SIM or device queue freezing. Besides the aforementioned flags the CAM subsystem provides functions `xpt_release_simq()` and `xpt_release_devq()` to unfreeze the queues directly, without passing a CCB to CAM.
 
 The CCB header contains the following fields:
 
 * _path_ - path ID for the request
 * _target_id_ - target device ID for the request
 * _target_lun_ - LUN ID of the target device
 * _timeout_ - timeout interval for this command, in milliseconds
 * _timeout_ch_ - a convenience place for the SIM driver to store the timeout handle (the CAM subsystem itself does not make any assumptions about it)
 * _flags_ - various bits of information about the request spriv_ptr0, spriv_ptr1 - fields reserved for private use by the SIM driver (such as linking to the SIM queues or SIM private control blocks); actually, they exist as unions: spriv_ptr0 and spriv_ptr1 have the type (void *), spriv_field0 and spriv_field1 have the type unsigned long, sim_priv.entries[0].bytes and sim_priv.entries[1].bytes are byte arrays of the size consistent with the other incarnations of the union and sim_priv.bytes is one array, twice bigger.
 
 The recommended way of using the SIM private fields of CCB is to define some meaningful names for them and use these meaningful names in the driver, like:
 
 [.programlisting]
 ....
 #define ccb_some_meaningful_name    sim_priv.entries[0].bytes
 #define ccb_hcb spriv_ptr1 /* for hardware control block */
 ....
 
 The most common initiator mode requests are:
 
 * _XPT_SCSI_IO_ - execute an I/O transaction
-+ 
++
 The instance "struct ccb_scsiio csio" of the union ccb is used to transfer the arguments. They are:
 
 ** _cdb_io_ - pointer to the SCSI command buffer or the buffer itself
 ** _cdb_len_ - SCSI command length
 ** _data_ptr_ - pointer to the data buffer (gets a bit complicated if scatter/gather is used)
 ** _dxfer_len_ - length of the data to transfer
 ** _sglist_cnt_ - counter of the scatter/gather segments
 ** _scsi_status_ - place to return the SCSI status
 ** _sense_data_ - buffer for the SCSI sense information if the command returns an error (the SIM driver is supposed to run the REQUEST SENSE command automatically in this case if the CCB flag CAM_DIS_AUTOSENSE is not set)
 ** _sense_len_ - the length of that buffer (if it happens to be higher than size of sense_data the SIM driver must silently assume the smaller value) resid, sense_resid - if the transfer of data or SCSI sense returned an error these are the returned counters of the residual (not transferred) data. They do not seem to be especially meaningful, so in a case when they are difficult to compute (say, counting bytes in the SCSI controller's FIFO buffer) an approximate value will do as well. For a successfully completed transfer they must be set to zero.
 ** _tag_action_ - the kind of tag to use:
 
 *** CAM_TAG_ACTION_NONE - do not use tags for this transaction
 *** MSG_SIMPLE_Q_TAG, MSG_HEAD_OF_Q_TAG, MSG_ORDERED_Q_TAG - value equal to the appropriate tag message (see /sys/cam/scsi/scsi_message.h); this gives only the tag type, the SIM driver must assign the tag value itself
-+ 
++
 The general logic of handling this request is the following:
-+ 
++
 The first thing to do is to check for possible races, to make sure that the command did not get aborted when it was sitting in the queue:
 +
 [.programlisting]
 ....
     struct ccb_scsiio *csio = &ccb->csio;
 
     if ((ccb_h->status & CAM_STATUS_MASK) != CAM_REQ_INPROG) {
         xpt_done(ccb);
         return;
     }
 ....
-+ 
++
 Also we check that the device is supported at all by our controller:
 +
 [.programlisting]
 ....
     if(ccb_h->target_id > OUR_MAX_SUPPORTED_TARGET_ID
     || cch_h->target_id == OUR_SCSI_CONTROLLERS_OWN_ID) {
         ccb_h->status = CAM_TID_INVALID;
         xpt_done(ccb);
         return;
     }
     if(ccb_h->target_lun > OUR_MAX_SUPPORTED_LUN) {
         ccb_h->status = CAM_LUN_INVALID;
         xpt_done(ccb);
         return;
     }
 ....
-+ 
++
 Then allocate whatever data structures (such as card-dependent hardware control block) we need to process this request. If we can not then freeze the SIM queue and remember that we have a pending operation, return the CCB back and ask CAM to re-queue it. Later when the resources become available the SIM queue must be unfrozen by returning a ccb with the `CAM_SIMQ_RELEASE` bit set in its status. Otherwise, if all went well, link the CCB with the hardware control block (HCB) and mark it as queued.
 +
 [.programlisting]
 ....
     struct xxx_hcb *hcb = allocate_hcb(softc, unit, bus);
 
     if(hcb == NULL) {
         softc->flags |= RESOURCE_SHORTAGE;
         xpt_freeze_simq(sim, /*count*/1);
         ccb_h->status = CAM_REQUEUE_REQ;
         xpt_done(ccb);
         return;
     }
 
     hcb->ccb = ccb; ccb_h->ccb_hcb = (void *)hcb;
     ccb_h->status |= CAM_SIM_QUEUED;
 ....
-+ 
++
 Extract the target data from CCB into the hardware control block. Check if we are asked to assign a tag and if yes then generate an unique tag and build the SCSI tag messages. The SIM driver is also responsible for negotiations with the devices to set the maximal mutually supported bus width, synchronous rate and offset.
 +
 [.programlisting]
 ....
     hcb->target = ccb_h->target_id; hcb->lun = ccb_h->target_lun;
     generate_identify_message(hcb);
     if( ccb_h->tag_action != CAM_TAG_ACTION_NONE )
         generate_unique_tag_message(hcb, ccb_h->tag_action);
     if( !target_negotiated(hcb) )
         generate_negotiation_messages(hcb);
 ....
-+ 
++
 Then set up the SCSI command. The command storage may be specified in the CCB in many interesting ways, specified by the CCB flags. The command buffer can be contained in CCB or pointed to, in the latter case the pointer may be physical or virtual. Since the hardware commonly needs physical address we always convert the address to the physical one, typically using the busdma API.
-+ 
++
 In case if a physical address is requested it is OK to return the CCB with the status `CAM_REQ_INVALID`, the current drivers do that. If necessary a physical address can be also converted or mapped back to a virtual address but with big pain, so we do not do that.
 +
 [.programlisting]
 ....
     if(ccb_h->flags & CAM_CDB_POINTER) {
         /* CDB is a pointer */
         if(!(ccb_h->flags & CAM_CDB_PHYS)) {
             /* CDB pointer is virtual */
             hcb->cmd = vtobus(csio->cdb_io.cdb_ptr);
         } else {
             /* CDB pointer is physical */
             hcb->cmd = csio->cdb_io.cdb_ptr ;
         }
     } else {
         /* CDB is in the ccb (buffer) */
         hcb->cmd = vtobus(csio->cdb_io.cdb_bytes);
     }
     hcb->cmdlen = csio->cdb_len;
 ....
-+ 
++
 Now it is time to set up the data. Again, the data storage may be specified in the CCB in many interesting ways, specified by the CCB flags. First we get the direction of the data transfer. The simplest case is if there is no data to transfer:
 +
 [.programlisting]
 ....
     int dir = (ccb_h->flags & CAM_DIR_MASK);
 
     if (dir == CAM_DIR_NONE)
         goto end_data;
 ....
-+ 
++
 Then we check if the data is in one chunk or in a scatter-gather list, and the addresses are physical or virtual. The SCSI controller may be able to handle only a limited number of chunks of limited length. If the request hits this limitation we return an error. We use a special function to return the CCB to handle in one place the HCB resource shortages. The functions to add chunks are driver-dependent, and here we leave them without detailed implementation. See description of the SCSI command (CDB) handling for the details on the address-translation issues. If some variation is too difficult or impossible to implement with a particular card it is OK to return the status `CAM_REQ_INVALID`. Actually, it seems like the scatter-gather ability is not used anywhere in the CAM code now. But at least the case for a single non-scattered virtual buffer must be implemented, it is actively used by CAM.
 +
 [.programlisting]
 ....
     int rv;
 
     initialize_hcb_for_data(hcb);
 
     if((!(ccb_h->flags & CAM_SCATTER_VALID)) {
         /* single buffer */
         if(!(ccb_h->flags & CAM_DATA_PHYS)) {
             rv = add_virtual_chunk(hcb, csio->data_ptr, csio->dxfer_len, dir);
             }
         } else {
             rv = add_physical_chunk(hcb, csio->data_ptr, csio->dxfer_len, dir);
         }
     } else {
         int i;
         struct bus_dma_segment *segs;
         segs = (struct bus_dma_segment *)csio->data_ptr;
 
         if ((ccb_h->flags & CAM_SG_LIST_PHYS) != 0) {
             /* The SG list pointer is physical */
             rv = setup_hcb_for_physical_sg_list(hcb, segs, csio->sglist_cnt);
         } else if (!(ccb_h->flags & CAM_DATA_PHYS)) {
             /* SG buffer pointers are virtual */
             for (i = 0; i < csio->sglist_cnt; i++) {
                 rv = add_virtual_chunk(hcb, segs[i].ds_addr,
                     segs[i].ds_len, dir);
                 if (rv != CAM_REQ_CMP)
                     break;
             }
         } else {
             /* SG buffer pointers are physical */
             for (i = 0; i < csio->sglist_cnt; i++) {
                 rv = add_physical_chunk(hcb, segs[i].ds_addr,
                     segs[i].ds_len, dir);
                 if (rv != CAM_REQ_CMP)
                     break;
             }
         }
     }
     if(rv != CAM_REQ_CMP) {
         /* we expect that add_*_chunk() functions return CAM_REQ_CMP
          * if they added a chunk successfully, CAM_REQ_TOO_BIG if
          * the request is too big (too many bytes or too many chunks),
          * CAM_REQ_INVALID in case of other troubles
          */
         free_hcb_and_ccb_done(hcb, ccb, rv);
         return;
     }
     end_data:
 ....
-+ 
++
 If disconnection is disabled for this CCB we pass this information to the hcb:
 +
 [.programlisting]
 ....
     if(ccb_h->flags & CAM_DIS_DISCONNECT)
         hcb_disable_disconnect(hcb);
 ....
-+ 
++
 If the controller is able to run REQUEST SENSE command all by itself then the value of the flag CAM_DIS_AUTOSENSE should also be passed to it, to prevent automatic REQUEST SENSE if the CAM subsystem does not want it.
-+ 
++
 The only thing left is to set up the timeout, pass our hcb to the hardware and return, the rest will be done by the interrupt handler (or timeout handler).
 +
 [.programlisting]
 ....
     ccb_h->timeout_ch = timeout(xxx_timeout, (caddr_t) hcb,
         (ccb_h->timeout * hz) / 1000); /* convert milliseconds to ticks */
     put_hcb_into_hardware_queue(hcb);
     return;
 ....
-+ 
++
 And here is a possible implementation of the function returning CCB:
 +
 [.programlisting]
 ....
     static void
     free_hcb_and_ccb_done(struct xxx_hcb *hcb, union ccb *ccb, u_int32_t status)
     {
         struct xxx_softc *softc = hcb->softc;
 
         ccb->ccb_h.ccb_hcb = 0;
         if(hcb != NULL) {
             untimeout(xxx_timeout, (caddr_t) hcb, ccb->ccb_h.timeout_ch);
             /* we're about to free a hcb, so the shortage has ended */
             if(softc->flags & RESOURCE_SHORTAGE)  {
                 softc->flags &= ~RESOURCE_SHORTAGE;
                 status |= CAM_RELEASE_SIMQ;
             }
             free_hcb(hcb); /* also removes hcb from any internal lists */
         }
         ccb->ccb_h.status = status |
             (ccb->ccb_h.status & ~(CAM_STATUS_MASK|CAM_SIM_QUEUED));
         xpt_done(ccb);
     }
 ....
 
 * _XPT_RESET_DEV_ - send the SCSI "BUS DEVICE RESET" message to a device
-+ 
++
 There is no data transferred in CCB except the header and the most interesting argument of it is target_id. Depending on the controller hardware a hardware control block just like for the XPT_SCSI_IO request may be constructed (see XPT_SCSI_IO request description) and sent to the controller or the SCSI controller may be immediately programmed to send this RESET message to the device or this request may be just not supported (and return the status `CAM_REQ_INVALID`). Also on completion of the request all the disconnected transactions for this target must be aborted (probably in the interrupt routine).
-+ 
++
 Also all the current negotiations for the target are lost on reset, so they might be cleaned too. Or they clearing may be deferred, because anyway the target would request re-negotiation on the next transaction.
 * _XPT_RESET_BUS_ - send the RESET signal to the SCSI bus
-+ 
++
 No arguments are passed in the CCB, the only interesting argument is the SCSI bus indicated by the struct sim pointer.
-+ 
++
 A minimalistic implementation would forget the SCSI negotiations for all the devices on the bus and return the status CAM_REQ_CMP.
-+ 
++
 The proper implementation would in addition actually reset the SCSI bus (possible also reset the SCSI controller) and mark all the CCBs being processed, both those in the hardware queue and those being disconnected, as done with the status CAM_SCSI_BUS_RESET. Like:
 +
 [.programlisting]
 ....
     int targ, lun;
     struct xxx_hcb *h, *hh;
     struct ccb_trans_settings neg;
     struct cam_path *path;
 
     /* The SCSI bus reset may take a long time, in this case its completion
      * should be checked by interrupt or timeout. But for simplicity
      * we assume here that it is really fast.
      */
     reset_scsi_bus(softc);
 
     /* drop all enqueued CCBs */
     for(h = softc->first_queued_hcb; h != NULL; h = hh) {
         hh = h->next;
         free_hcb_and_ccb_done(h, h->ccb, CAM_SCSI_BUS_RESET);
     }
 
     /* the clean values of negotiations to report */
     neg.bus_width = 8;
     neg.sync_period = neg.sync_offset = 0;
     neg.valid = (CCB_TRANS_BUS_WIDTH_VALID
         | CCB_TRANS_SYNC_RATE_VALID | CCB_TRANS_SYNC_OFFSET_VALID);
 
     /* drop all disconnected CCBs and clean negotiations  */
     for(targ=0; targ <= OUR_MAX_SUPPORTED_TARGET; targ++) {
         clean_negotiations(softc, targ);
 
         /* report the event if possible */
         if(xpt_create_path(&path, /*periph*/NULL,
                 cam_sim_path(sim), targ,
                 CAM_LUN_WILDCARD) == CAM_REQ_CMP) {
             xpt_async(AC_TRANSFER_NEG, path, &neg);
             xpt_free_path(path);
         }
 
         for(lun=0; lun <= OUR_MAX_SUPPORTED_LUN; lun++)
             for(h = softc->first_discon_hcb[targ][lun]; h != NULL; h = hh) {
                 hh=h->next;
                 free_hcb_and_ccb_done(h, h->ccb, CAM_SCSI_BUS_RESET);
             }
     }
 
     ccb->ccb_h.status = CAM_REQ_CMP;
     xpt_done(ccb);
 
     /* report the event */
     xpt_async(AC_BUS_RESET, softc->wpath, NULL);
     return;
 ....
-+ 
++
 Implementing the SCSI bus reset as a function may be a good idea because it would be re-used by the timeout function as a last resort if the things go wrong.
 * _XPT_ABORT_ - abort the specified CCB
-+ 
++
 The arguments are transferred in the instance "struct ccb_abort cab" of the union ccb. The only argument field in it is:
-+ 
++
 _abort_ccb_ - pointer to the CCB to be aborted
-+ 
++
 If the abort is not supported just return the status CAM_UA_ABORT. This is also the easy way to minimally implement this call, return CAM_UA_ABORT in any case.
-+ 
++
 The hard way is to implement this request honestly. First check that abort applies to a SCSI transaction:
 +
 [.programlisting]
 ....
     struct ccb *abort_ccb;
     abort_ccb = ccb->cab.abort_ccb;
 
     if(abort_ccb->ccb_h.func_code != XPT_SCSI_IO) {
         ccb->ccb_h.status = CAM_UA_ABORT;
         xpt_done(ccb);
         return;
     }
 ....
 
-+ 
++
 Then it is necessary to find this CCB in our queue. This can be done by walking the list of all our hardware control blocks in search for one associated with this CCB:
 +
 [.programlisting]
 ....
     struct xxx_hcb *hcb, *h;
 
     hcb = NULL;
 
     /* We assume that softc->first_hcb is the head of the list of all
      * HCBs associated with this bus, including those enqueued for
      * processing, being processed by hardware and disconnected ones.
      */
     for(h = softc->first_hcb; h != NULL; h = h->next) {
         if(h->ccb == abort_ccb) {
             hcb = h;
             break;
         }
     }
 
     if(hcb == NULL) {
         /* no such CCB in our queue */
         ccb->ccb_h.status = CAM_PATH_INVALID;
         xpt_done(ccb);
         return;
     }
 
     hcb=found_hcb;
 ....
-+ 
++
 Now we look at the current processing status of the HCB. It may be either sitting in the queue waiting to be sent to the SCSI bus, being transferred right now, or disconnected and waiting for the result of the command, or actually completed by hardware but not yet marked as done by software. To make sure that we do not get in any races with hardware we mark the HCB as being aborted, so that if this HCB is about to be sent to the SCSI bus the SCSI controller will see this flag and skip it.
 +
 [.programlisting]
 ....
     int hstatus;
 
     /* shown as a function, in case special action is needed to make
      * this flag visible to hardware
      */
     set_hcb_flags(hcb, HCB_BEING_ABORTED);
 
     abort_again:
 
     hstatus = get_hcb_status(hcb);
     switch(hstatus) {
     case HCB_SITTING_IN_QUEUE:
         remove_hcb_from_hardware_queue(hcb);
         /* FALLTHROUGH */
     case HCB_COMPLETED:
         /* this is an easy case */
         free_hcb_and_ccb_done(hcb, abort_ccb, CAM_REQ_ABORTED);
         break;
 ....
-+ 
++
 If the CCB is being transferred right now we would like to signal to the SCSI controller in some hardware-dependent way that we want to abort the current transfer. The SCSI controller would set the SCSI ATTENTION signal and when the target responds to it send an ABORT message. We also reset the timeout to make sure that the target is not sleeping forever. If the command would not get aborted in some reasonable time like 10 seconds the timeout routine would go ahead and reset the whole SCSI bus. Since the command will be aborted in some reasonable time we can just return the abort request now as successfully completed, and mark the aborted CCB as aborted (but not mark it as done yet).
 +
 [.programlisting]
 ....
     case HCB_BEING_TRANSFERRED:
         untimeout(xxx_timeout, (caddr_t) hcb, abort_ccb->ccb_h.timeout_ch);
         abort_ccb->ccb_h.timeout_ch =
             timeout(xxx_timeout, (caddr_t) hcb, 10 * hz);
         abort_ccb->ccb_h.status = CAM_REQ_ABORTED;
         /* ask the controller to abort that HCB, then generate
          * an interrupt and stop
          */
         if(signal_hardware_to_abort_hcb_and_stop(hcb) < 0) {
             /* oops, we missed the race with hardware, this transaction
              * got off the bus before we aborted it, try again */
             goto abort_again;
         }
 
         break;
 ....
-+ 
++
 If the CCB is in the list of disconnected then set it up as an abort request and re-queue it at the front of hardware queue. Reset the timeout and report the abort request to be completed.
 +
 [.programlisting]
 ....
     case HCB_DISCONNECTED:
         untimeout(xxx_timeout, (caddr_t) hcb, abort_ccb->ccb_h.timeout_ch);
         abort_ccb->ccb_h.timeout_ch =
             timeout(xxx_timeout, (caddr_t) hcb, 10 * hz);
         put_abort_message_into_hcb(hcb);
         put_hcb_at_the_front_of_hardware_queue(hcb);
         break;
     }
     ccb->ccb_h.status = CAM_REQ_CMP;
     xpt_done(ccb);
     return;
 ....
-+ 
++
 That is all for the ABORT request, although there is one more issue. As the ABORT message cleans all the ongoing transactions on a LUN we have to mark all the other active transactions on this LUN as aborted. That should be done in the interrupt routine, after the transaction gets aborted.
-+ 
++
 Implementing the CCB abort as a function may be quite a good idea, this function can be re-used if an I/O transaction times out. The only difference would be that the timed out transaction would return the status CAM_CMD_TIMEOUT for the timed out request. Then the case XPT_ABORT would be small, like that:
 +
 [.programlisting]
 ....
     case XPT_ABORT:
         struct ccb *abort_ccb;
         abort_ccb = ccb->cab.abort_ccb;
 
         if(abort_ccb->ccb_h.func_code != XPT_SCSI_IO) {
             ccb->ccb_h.status = CAM_UA_ABORT;
             xpt_done(ccb);
             return;
         }
         if(xxx_abort_ccb(abort_ccb, CAM_REQ_ABORTED) < 0)
             /* no such CCB in our queue */
             ccb->ccb_h.status = CAM_PATH_INVALID;
         else
             ccb->ccb_h.status = CAM_REQ_CMP;
         xpt_done(ccb);
         return;
 ....
 
 * _XPT_SET_TRAN_SETTINGS_ - explicitly set values of SCSI transfer settings
-+ 
++
 The arguments are transferred in the instance "struct ccb_trans_setting cts" of the union ccb:
 
 ** _valid_ - a bitmask showing which settings should be updated:
 ** _CCB_TRANS_SYNC_RATE_VALID_ - synchronous transfer rate
 ** _CCB_TRANS_SYNC_OFFSET_VALID_ - synchronous offset
 ** _CCB_TRANS_BUS_WIDTH_VALID_ - bus width
 ** _CCB_TRANS_DISC_VALID_ - set enable/disable disconnection
 ** _CCB_TRANS_TQ_VALID_ - set enable/disable tagged queuing
 ** _flags_ - consists of two parts, binary arguments and identification of sub-operations. The binary arguments are:
 
 *** _CCB_TRANS_DISC_ENB_ - enable disconnection
 *** _CCB_TRANS_TAG_ENB_ - enable tagged queuing
 
 ** the sub-operations are:
 
 *** _CCB_TRANS_CURRENT_SETTINGS_ - change the current negotiations
 *** _CCB_TRANS_USER_SETTINGS_ - remember the desired user values sync_period, sync_offset - self-explanatory, if sync_offset==0 then the asynchronous mode is requested bus_width - bus width, in bits (not bytes)
-+ 
++
 Two sets of negotiated parameters are supported, the user settings and the current settings. The user settings are not really used much in the SIM drivers, this is mostly just a piece of memory where the upper levels can store (and later recall) its ideas about the parameters. Setting the user parameters does not cause re-negotiation of the transfer rates. But when the SCSI controller does a negotiation it must never set the values higher than the user parameters, so it is essentially the top boundary.
-+ 
++
 The current settings are, as the name says, current. Changing them means that the parameters must be re-negotiated on the next transfer. Again, these "new current settings" are not supposed to be forced on the device, just they are used as the initial step of negotiations. Also they must be limited by actual capabilities of the SCSI controller: for example, if the SCSI controller has 8-bit bus and the request asks to set 16-bit wide transfers this parameter must be silently truncated to 8-bit transfers before sending it to the device.
-+ 
++
 One caveat is that the bus width and synchronous parameters are per target while the disconnection and tag enabling parameters are per lun.
-+ 
++
 The recommended implementation is to keep 3 sets of negotiated (bus width and synchronous transfer) parameters:
 
 ** _user_ - the user set, as above
 ** _current_ - those actually in effect
 ** _goal_ - those requested by setting of the "current" parameters
-+ 
++
 The code looks like:
 +
 [.programlisting]
 ....
     struct ccb_trans_settings *cts;
     int targ, lun;
     int flags;
 
     cts = &ccb->cts;
     targ = ccb_h->target_id;
     lun = ccb_h->target_lun;
     flags = cts->flags;
     if(flags & CCB_TRANS_USER_SETTINGS) {
         if(flags & CCB_TRANS_SYNC_RATE_VALID)
             softc->user_sync_period[targ] = cts->sync_period;
         if(flags & CCB_TRANS_SYNC_OFFSET_VALID)
             softc->user_sync_offset[targ] = cts->sync_offset;
         if(flags & CCB_TRANS_BUS_WIDTH_VALID)
             softc->user_bus_width[targ] = cts->bus_width;
 
         if(flags & CCB_TRANS_DISC_VALID) {
             softc->user_tflags[targ][lun] &= ~CCB_TRANS_DISC_ENB;
             softc->user_tflags[targ][lun] |= flags & CCB_TRANS_DISC_ENB;
         }
         if(flags & CCB_TRANS_TQ_VALID) {
             softc->user_tflags[targ][lun] &= ~CCB_TRANS_TQ_ENB;
             softc->user_tflags[targ][lun] |= flags & CCB_TRANS_TQ_ENB;
         }
     }
     if(flags & CCB_TRANS_CURRENT_SETTINGS) {
         if(flags & CCB_TRANS_SYNC_RATE_VALID)
             softc->goal_sync_period[targ] =
                 max(cts->sync_period, OUR_MIN_SUPPORTED_PERIOD);
         if(flags & CCB_TRANS_SYNC_OFFSET_VALID)
             softc->goal_sync_offset[targ] =
                 min(cts->sync_offset, OUR_MAX_SUPPORTED_OFFSET);
         if(flags & CCB_TRANS_BUS_WIDTH_VALID)
             softc->goal_bus_width[targ] = min(cts->bus_width, OUR_BUS_WIDTH);
 
         if(flags & CCB_TRANS_DISC_VALID) {
             softc->current_tflags[targ][lun] &= ~CCB_TRANS_DISC_ENB;
             softc->current_tflags[targ][lun] |= flags & CCB_TRANS_DISC_ENB;
         }
         if(flags & CCB_TRANS_TQ_VALID) {
             softc->current_tflags[targ][lun] &= ~CCB_TRANS_TQ_ENB;
             softc->current_tflags[targ][lun] |= flags & CCB_TRANS_TQ_ENB;
         }
     }
     ccb->ccb_h.status = CAM_REQ_CMP;
     xpt_done(ccb);
     return;
 ....
-+ 
++
 Then when the next I/O request will be processed it will check if it has to re-negotiate, for example by calling the function target_negotiated(hcb). It can be implemented like this:
 +
 [.programlisting]
 ....
     int
     target_negotiated(struct xxx_hcb *hcb)
     {
         struct softc *softc = hcb->softc;
         int targ = hcb->targ;
 
         if( softc->current_sync_period[targ] != softc->goal_sync_period[targ]
         || softc->current_sync_offset[targ] != softc->goal_sync_offset[targ]
         || softc->current_bus_width[targ] != softc->goal_bus_width[targ] )
             return 0; /* FALSE */
         else
             return 1; /* TRUE */
     }
 ....
-+ 
++
 After the values are re-negotiated the resulting values must be assigned to both current and goal parameters, so for future I/O transactions the current and goal parameters would be the same and `target_negotiated()` would return TRUE. When the card is initialized (in `xxx_attach()`) the current negotiation values must be initialized to narrow asynchronous mode, the goal and current values must be initialized to the maximal values supported by controller.
-+ 
++
 _XPT_GET_TRAN_SETTINGS_ - get values of SCSI transfer settings
-+ 
++
 This operations is the reverse of XPT_SET_TRAN_SETTINGS. Fill up the CCB instance "struct ccb_trans_setting cts" with data as requested by the flags CCB_TRANS_CURRENT_SETTINGS or CCB_TRANS_USER_SETTINGS (if both are set then the existing drivers return the current settings). Set all the bits in the valid field.
-+ 
++
 _XPT_CALC_GEOMETRY_ - calculate logical (BIOS) geometry of the disk
-+ 
++
 The arguments are transferred in the instance "struct ccb_calc_geometry ccg" of the union ccb:
 
 ** _block_size_ - input, block (A.K.A sector) size in bytes
 ** _volume_size_ - input, volume size in bytes
 ** _cylinders_ - output, logical cylinders
 ** _heads_ - output, logical heads
 ** _secs_per_track_ - output, logical sectors per track
-+ 
++
 If the returned geometry differs much enough from what the SCSI controller BIOS thinks and a disk on this SCSI controller is used as bootable the system may not be able to boot. The typical calculation example taken from the aic7xxx driver is:
 +
 [.programlisting]
 ....
     struct    ccb_calc_geometry *ccg;
     u_int32_t size_mb;
     u_int32_t secs_per_cylinder;
     int   extended;
 
     ccg = &ccb->ccg;
     size_mb = ccg->volume_size
         / ((1024L * 1024L) / ccg->block_size);
     extended = check_cards_EEPROM_for_extended_geometry(softc);
 
     if (size_mb > 1024 && extended) {
         ccg->heads = 255;
         ccg->secs_per_track = 63;
     } else {
         ccg->heads = 64;
         ccg->secs_per_track = 32;
     }
     secs_per_cylinder = ccg->heads * ccg->secs_per_track;
     ccg->cylinders = ccg->volume_size / secs_per_cylinder;
     ccb->ccb_h.status = CAM_REQ_CMP;
     xpt_done(ccb);
     return;
 ....
-+ 
++
 This gives the general idea, the exact calculation depends on the quirks of the particular BIOS. If BIOS provides no way set the "extended translation" flag in EEPROM this flag should normally be assumed equal to 1. Other popular geometries are:
 +
 [.programlisting]
 ....
     128 heads, 63 sectors - Symbios controllers
     16 heads, 63 sectors - old controllers
 ....
-+ 
++
 Some system BIOSes and SCSI BIOSes fight with each other with variable success, for example a combination of Symbios 875/895 SCSI and Phoenix BIOS can give geometry 128/63 after power up and 255/63 after a hard reset or soft reboot.
 * _XPT_PATH_INQ_ - path inquiry, in other words get the SIM driver and SCSI controller (also known as HBA - Host Bus Adapter) properties
-+ 
++
 The properties are returned in the instance "struct ccb_pathinq cpi" of the union ccb:
 
 ** version_num - the SIM driver version number, now all drivers use 1
 ** hba_inquiry - bitmask of features supported by the controller:
 ** PI_MDP_ABLE - supports MDP message (something from SCSI3?)
 ** PI_WIDE_32 - supports 32 bit wide SCSI
 ** PI_WIDE_16 - supports 16 bit wide SCSI
 ** PI_SDTR_ABLE - can negotiate synchronous transfer rate
 ** PI_LINKED_CDB - supports linked commands
 ** PI_TAG_ABLE - supports tagged commands
 ** PI_SOFT_RST - supports soft reset alternative (hard reset and soft reset are mutually exclusive within a SCSI bus)
 ** target_sprt - flags for target mode support, 0 if unsupported
 ** hba_misc - miscellaneous controller features:
 ** PIM_SCANHILO - bus scans from high ID to low ID
 ** PIM_NOREMOVE - removable devices not included in scan
 ** PIM_NOINITIATOR - initiator role not supported
 ** PIM_NOBUSRESET - user has disabled initial BUS RESET
 ** hba_eng_cnt - mysterious HBA engine count, something related to compression, now is always set to 0
 ** vuhba_flags - vendor-unique flags, unused now
 ** max_target - maximal supported target ID (7 for 8-bit bus, 15 for 16-bit bus, 127 for Fibre Channel)
 ** max_lun - maximal supported LUN ID (7 for older SCSI controllers, 63 for newer ones)
 ** async_flags - bitmask of installed Async handler, unused now
 ** hpath_id - highest Path ID in the subsystem, unused now
 ** unit_number - the controller unit number, cam_sim_unit(sim)
 ** bus_id - the bus number, cam_sim_bus(sim)
 ** initiator_id - the SCSI ID of the controller itself
 ** base_transfer_speed - nominal transfer speed in KB/s for asynchronous narrow transfers, equals to 3300 for SCSI
 ** sim_vid - SIM driver's vendor id, a zero-terminated string of maximal length SIM_IDLEN including the terminating zero
 ** hba_vid - SCSI controller's vendor id, a zero-terminated string of maximal length HBA_IDLEN including the terminating zero
 ** dev_name - device driver name, a zero-terminated string of maximal length DEV_IDLEN including the terminating zero, equal to cam_sim_name(sim)
-+ 
++
 The recommended way of setting the string fields is using strncpy, like:
 +
 [.programlisting]
 ....
     strncpy(cpi->dev_name, cam_sim_name(sim), DEV_IDLEN);
 ....
-+ 
++
 After setting the values set the status to CAM_REQ_CMP and mark the CCB as done.
 
 [[scsi-polling]]
 == Polling
 
 [source,c]
 ----
 static void
 	  xxx_poll
 	 ();
 ----
 
 The poll function is used to simulate the interrupts when the interrupt subsystem is not functioning (for example, when the system has crashed and is creating the system dump). The CAM subsystem sets the proper interrupt level before calling the poll routine. So all it needs to do is to call the interrupt routine (or the other way around, the poll routine may be doing the real action and the interrupt routine would just call the poll routine). Why bother about a separate function then? This has to do with different calling conventions. The `xxx_poll` routine gets the struct cam_sim pointer as its argument while the PCI interrupt routine by common convention gets pointer to the struct `xxx_softc` and the ISA interrupt routine gets just the device unit number. So the poll routine would normally look as:
 
 [.programlisting]
 ....
 static void
 xxx_poll(struct cam_sim *sim)
 {
     xxx_intr((struct xxx_softc *)cam_sim_softc(sim)); /* for PCI device */
 }
 ....
 
 or
 
 [.programlisting]
 ....
 static void
 xxx_poll(struct cam_sim *sim)
 {
     xxx_intr(cam_sim_unit(sim)); /* for ISA device */
 }
 ....
 
 [[scsi-async]]
 == Asynchronous Events
 
 If an asynchronous event callback has been set up then the callback function should be defined.
 
 [.programlisting]
 ....
 static void
 ahc_async(void *callback_arg, u_int32_t code, struct cam_path *path, void *arg)
 ....
 
 * callback_arg - the value supplied when registering the callback
 * code - identifies the type of event
 * path - identifies the devices to which the event applies
 * arg - event-specific argument
 
 Implementation for a single type of event, AC_LOST_DEVICE, looks like:
 
 [.programlisting]
 ....
     struct xxx_softc *softc;
     struct cam_sim *sim;
     int targ;
     struct ccb_trans_settings neg;
 
     sim = (struct cam_sim *)callback_arg;
     softc = (struct xxx_softc *)cam_sim_softc(sim);
     switch (code) {
     case AC_LOST_DEVICE:
         targ = xpt_path_target_id(path);
         if(targ <= OUR_MAX_SUPPORTED_TARGET) {
             clean_negotiations(softc, targ);
             /* send indication to CAM */
             neg.bus_width = 8;
             neg.sync_period = neg.sync_offset = 0;
             neg.valid = (CCB_TRANS_BUS_WIDTH_VALID
                 | CCB_TRANS_SYNC_RATE_VALID | CCB_TRANS_SYNC_OFFSET_VALID);
             xpt_async(AC_TRANSFER_NEG, path, &neg);
         }
         break;
     default:
         break;
     }
 ....
 
 [[scsi-interrupts]]
 == Interrupts
 
 The exact type of the interrupt routine depends on the type of the peripheral bus (PCI, ISA and so on) to which the SCSI controller is connected.
 
 The interrupt routines of the SIM drivers run at the interrupt level splcam. So `splcam()` should be used in the driver to synchronize activity between the interrupt routine and the rest of the driver (for a multiprocessor-aware driver things get yet more interesting but we ignore this case here). The pseudo-code in this document happily ignores the problems of synchronization. The real code must not ignore them. A simple-minded approach is to set `splcam()` on the entry to the other routines and reset it on return thus protecting them by one big critical section. To make sure that the interrupt level will be always restored a wrapper function can be defined, like:
 
 [.programlisting]
 ....
     static void
     xxx_action(struct cam_sim *sim, union ccb *ccb)
     {
         int s;
         s = splcam();
         xxx_action1(sim, ccb);
         splx(s);
     }
 
     static void
     xxx_action1(struct cam_sim *sim, union ccb *ccb)
     {
         ... process the request ...
     }
 ....
 
 This approach is simple and robust but the problem with it is that interrupts may get blocked for a relatively long time and this would negatively affect the system's performance. On the other hand the functions of the `spl()` family have rather high overhead, so vast amount of tiny critical sections may not be good either.
 
 The conditions handled by the interrupt routine and the details depend very much on the hardware. We consider the set of "typical" conditions.
 
 First, we check if a SCSI reset was encountered on the bus (probably caused by another SCSI controller on the same SCSI bus). If so we drop all the enqueued and disconnected requests, report the events and re-initialize our SCSI controller. It is important that during this initialization the controller will not issue another reset or else two controllers on the same SCSI bus could ping-pong resets forever. The case of fatal controller error/hang could be handled in the same place, but it will probably need also sending RESET signal to the SCSI bus to reset the status of the connections with the SCSI devices.
 
 [.programlisting]
 ....
     int fatal=0;
     struct ccb_trans_settings neg;
     struct cam_path *path;
 
     if( detected_scsi_reset(softc)
     || (fatal = detected_fatal_controller_error(softc)) ) {
         int targ, lun;
         struct xxx_hcb *h, *hh;
 
         /* drop all enqueued CCBs */
         for(h = softc->first_queued_hcb; h != NULL; h = hh) {
             hh = h->next;
             free_hcb_and_ccb_done(h, h->ccb, CAM_SCSI_BUS_RESET);
         }
 
         /* the clean values of negotiations to report */
         neg.bus_width = 8;
         neg.sync_period = neg.sync_offset = 0;
         neg.valid = (CCB_TRANS_BUS_WIDTH_VALID
             | CCB_TRANS_SYNC_RATE_VALID | CCB_TRANS_SYNC_OFFSET_VALID);
 
         /* drop all disconnected CCBs and clean negotiations  */
         for(targ=0; targ <= OUR_MAX_SUPPORTED_TARGET; targ++) {
             clean_negotiations(softc, targ);
 
             /* report the event if possible */
             if(xpt_create_path(&path, /*periph*/NULL,
                     cam_sim_path(sim), targ,
                     CAM_LUN_WILDCARD) == CAM_REQ_CMP) {
                 xpt_async(AC_TRANSFER_NEG, path, &neg);
                 xpt_free_path(path);
             }
 
             for(lun=0; lun <= OUR_MAX_SUPPORTED_LUN; lun++)
                 for(h = softc->first_discon_hcb[targ][lun]; h != NULL; h = hh) {
                     hh=h->next;
                     if(fatal)
                         free_hcb_and_ccb_done(h, h->ccb, CAM_UNREC_HBA_ERROR);
                     else
                         free_hcb_and_ccb_done(h, h->ccb, CAM_SCSI_BUS_RESET);
                 }
         }
 
         /* report the event */
         xpt_async(AC_BUS_RESET, softc->wpath, NULL);
 
         /* re-initialization may take a lot of time, in such case
          * its completion should be signaled by another interrupt or
          * checked on timeout - but for simplicity we assume here that
          * it is really fast
          */
         if(!fatal) {
             reinitialize_controller_without_scsi_reset(softc);
         } else {
             reinitialize_controller_with_scsi_reset(softc);
         }
         schedule_next_hcb(softc);
         return;
     }
 ....
 
 If interrupt is not caused by a controller-wide condition then probably something has happened to the current hardware control block. Depending on the hardware there may be other non-HCB-related events, we just do not consider them here. Then we analyze what happened to this HCB:
 
 [.programlisting]
 ....
     struct xxx_hcb *hcb, *h, *hh;
     int hcb_status, scsi_status;
     int ccb_status;
     int targ;
     int lun_to_freeze;
 
     hcb = get_current_hcb(softc);
     if(hcb == NULL) {
         /* either stray interrupt or something went very wrong
          * or this is something hardware-dependent
          */
         handle as necessary;
         return;
     }
 
     targ = hcb->target;
     hcb_status = get_status_of_current_hcb(softc);
 ....
 
 First we check if the HCB has completed and if so we check the returned SCSI status.
 
 [.programlisting]
 ....
     if(hcb_status == COMPLETED) {
         scsi_status = get_completion_status(hcb);
 ....
 
 Then look if this status is related to the REQUEST SENSE command and if so handle it in a simple way.
 
 [.programlisting]
 ....
         if(hcb->flags & DOING_AUTOSENSE) {
             if(scsi_status == GOOD) { /* autosense was successful */
                 hcb->ccb->ccb_h.status |= CAM_AUTOSNS_VALID;
                 free_hcb_and_ccb_done(hcb, hcb->ccb, CAM_SCSI_STATUS_ERROR);
             } else {
         autosense_failed:
                 free_hcb_and_ccb_done(hcb, hcb->ccb, CAM_AUTOSENSE_FAIL);
             }
             schedule_next_hcb(softc);
             return;
         }
 ....
 
 Else the command itself has completed, pay more attention to details. If auto-sense is not disabled for this CCB and the command has failed with sense data then run REQUEST SENSE command to receive that data.
 
 [.programlisting]
 ....
         hcb->ccb->csio.scsi_status = scsi_status;
         calculate_residue(hcb);
 
         if( (hcb->ccb->ccb_h.flags & CAM_DIS_AUTOSENSE)==0
         && ( scsi_status == CHECK_CONDITION
                 || scsi_status == COMMAND_TERMINATED) ) {
             /* start auto-SENSE */
             hcb->flags |= DOING_AUTOSENSE;
             setup_autosense_command_in_hcb(hcb);
             restart_current_hcb(softc);
             return;
         }
         if(scsi_status == GOOD)
             free_hcb_and_ccb_done(hcb, hcb->ccb, CAM_REQ_CMP);
         else
             free_hcb_and_ccb_done(hcb, hcb->ccb, CAM_SCSI_STATUS_ERROR);
         schedule_next_hcb(softc);
         return;
     }
 ....
 
 One typical thing would be negotiation events: negotiation messages received from a SCSI target (in answer to our negotiation attempt or by target's initiative) or the target is unable to negotiate (rejects our negotiation messages or does not answer them).
 
 [.programlisting]
 ....
     switch(hcb_status) {
     case TARGET_REJECTED_WIDE_NEG:
         /* revert to 8-bit bus */
         softc->current_bus_width[targ] = softc->goal_bus_width[targ] = 8;
         /* report the event */
         neg.bus_width = 8;
         neg.valid = CCB_TRANS_BUS_WIDTH_VALID;
         xpt_async(AC_TRANSFER_NEG, hcb->ccb.ccb_h.path_id, &neg);
         continue_current_hcb(softc);
         return;
     case TARGET_ANSWERED_WIDE_NEG:
         {
             int wd;
 
             wd = get_target_bus_width_request(softc);
             if(wd <= softc->goal_bus_width[targ]) {
                 /* answer is acceptable */
                 softc->current_bus_width[targ] =
                 softc->goal_bus_width[targ] = neg.bus_width = wd;
 
                 /* report the event */
                 neg.valid = CCB_TRANS_BUS_WIDTH_VALID;
                 xpt_async(AC_TRANSFER_NEG, hcb->ccb.ccb_h.path_id, &neg);
             } else {
                 prepare_reject_message(hcb);
             }
         }
         continue_current_hcb(softc);
         return;
     case TARGET_REQUESTED_WIDE_NEG:
         {
             int wd;
 
             wd = get_target_bus_width_request(softc);
             wd = min (wd, OUR_BUS_WIDTH);
             wd = min (wd, softc->user_bus_width[targ]);
 
             if(wd != softc->current_bus_width[targ]) {
                 /* the bus width has changed */
                 softc->current_bus_width[targ] =
                 softc->goal_bus_width[targ] = neg.bus_width = wd;
 
                 /* report the event */
                 neg.valid = CCB_TRANS_BUS_WIDTH_VALID;
                 xpt_async(AC_TRANSFER_NEG, hcb->ccb.ccb_h.path_id, &neg);
             }
             prepare_width_nego_rsponse(hcb, wd);
         }
         continue_current_hcb(softc);
         return;
     }
 ....
 
 Then we handle any errors that could have happened during auto-sense in the same simple-minded way as before. Otherwise we look closer at the details again.
 
 [.programlisting]
 ....
     if(hcb->flags & DOING_AUTOSENSE)
         goto autosense_failed;
 
     switch(hcb_status) {
 ....
 
 The next event we consider is unexpected disconnect. Which is considered normal after an ABORT or BUS DEVICE RESET message and abnormal in other cases.
 
 [.programlisting]
 ....
     case UNEXPECTED_DISCONNECT:
         if(requested_abort(hcb)) {
             /* abort affects all commands on that target+LUN, so
              * mark all disconnected HCBs on that target+LUN as aborted too
              */
             for(h = softc->first_discon_hcb[hcb->target][hcb->lun];
                     h != NULL; h = hh) {
                 hh=h->next;
                 free_hcb_and_ccb_done(h, h->ccb, CAM_REQ_ABORTED);
             }
             ccb_status = CAM_REQ_ABORTED;
         } else if(requested_bus_device_reset(hcb)) {
             int lun;
 
             /* reset affects all commands on that target, so
              * mark all disconnected HCBs on that target+LUN as reset
              */
 
             for(lun=0; lun <= OUR_MAX_SUPPORTED_LUN; lun++)
                 for(h = softc->first_discon_hcb[hcb->target][lun];
                         h != NULL; h = hh) {
                     hh=h->next;
                     free_hcb_and_ccb_done(h, h->ccb, CAM_SCSI_BUS_RESET);
                 }
 
             /* send event */
             xpt_async(AC_SENT_BDR, hcb->ccb->ccb_h.path_id, NULL);
 
             /* this was the CAM_RESET_DEV request itself, it is completed */
             ccb_status = CAM_REQ_CMP;
         } else {
             calculate_residue(hcb);
             ccb_status = CAM_UNEXP_BUSFREE;
             /* request the further code to freeze the queue */
             hcb->ccb->ccb_h.status |= CAM_DEV_QFRZN;
             lun_to_freeze = hcb->lun;
         }
         break;
 ....
 
 If the target refuses to accept tags we notify CAM about that and return back all commands for this LUN:
 
 [.programlisting]
 ....
     case TAGS_REJECTED:
         /* report the event */
         neg.flags = 0 & ~CCB_TRANS_TAG_ENB;
         neg.valid = CCB_TRANS_TQ_VALID;
         xpt_async(AC_TRANSFER_NEG, hcb->ccb.ccb_h.path_id, &neg);
 
         ccb_status = CAM_MSG_REJECT_REC;
         /* request the further code to freeze the queue */
         hcb->ccb->ccb_h.status |= CAM_DEV_QFRZN;
         lun_to_freeze = hcb->lun;
         break;
 ....
 
 Then we check a number of other conditions, with processing basically limited to setting the CCB status:
 
 [.programlisting]
 ....
     case SELECTION_TIMEOUT:
         ccb_status = CAM_SEL_TIMEOUT;
         /* request the further code to freeze the queue */
         hcb->ccb->ccb_h.status |= CAM_DEV_QFRZN;
         lun_to_freeze = CAM_LUN_WILDCARD;
         break;
     case PARITY_ERROR:
         ccb_status = CAM_UNCOR_PARITY;
         break;
     case DATA_OVERRUN:
     case ODD_WIDE_TRANSFER:
         ccb_status = CAM_DATA_RUN_ERR;
         break;
     default:
         /* all other errors are handled in a generic way */
         ccb_status = CAM_REQ_CMP_ERR;
         /* request the further code to freeze the queue */
         hcb->ccb->ccb_h.status |= CAM_DEV_QFRZN;
         lun_to_freeze = CAM_LUN_WILDCARD;
         break;
     }
 ....
 
 Then we check if the error was serious enough to freeze the input queue until it gets proceeded and do so if it is:
 
 [.programlisting]
 ....
     if(hcb->ccb->ccb_h.status & CAM_DEV_QFRZN) {
         /* freeze the queue */
         xpt_freeze_devq(ccb->ccb_h.path, /*count*/1);
 
         /* re-queue all commands for this target/LUN back to CAM */
 
         for(h = softc->first_queued_hcb; h != NULL; h = hh) {
             hh = h->next;
 
             if(targ == h->targ
             && (lun_to_freeze == CAM_LUN_WILDCARD || lun_to_freeze == h->lun) )
                 free_hcb_and_ccb_done(h, h->ccb, CAM_REQUEUE_REQ);
         }
     }
     free_hcb_and_ccb_done(hcb, hcb->ccb, ccb_status);
     schedule_next_hcb(softc);
     return;
 ....
 
 This concludes the generic interrupt handling although specific controllers may require some additions.
 
 [[scsi-errors]]
 == Errors Summary
 
 When executing an I/O request many things may go wrong. The reason of error can be reported in the CCB status with great detail. Examples of use are spread throughout this document. For completeness here is the summary of recommended responses for the typical error conditions:
 
 * _CAM_RESRC_UNAVAIL_ - some resource is temporarily unavailable and the SIM driver cannot generate an event when it will become available. An example of this resource would be some intra-controller hardware resource for which the controller does not generate an interrupt when it becomes available.
 * _CAM_UNCOR_PARITY_ - unrecovered parity error occurred
 * _CAM_DATA_RUN_ERR_ - data overrun or unexpected data phase (going in other direction than specified in CAM_DIR_MASK) or odd transfer length for wide transfer
 * _CAM_SEL_TIMEOUT_ - selection timeout occurred (target does not respond)
 * _CAM_CMD_TIMEOUT_ - command timeout occurred (the timeout function ran)
 * _CAM_SCSI_STATUS_ERROR_ - the device returned error
 * _CAM_AUTOSENSE_FAIL_ - the device returned error and the REQUEST SENSE COMMAND failed
 * _CAM_MSG_REJECT_REC_ - MESSAGE REJECT message was received
 * _CAM_SCSI_BUS_RESET_ - received SCSI bus reset
 * _CAM_REQ_CMP_ERR_ - "impossible" SCSI phase occurred or something else as weird or just a generic error if further detail is not available
 * _CAM_UNEXP_BUSFREE_ - unexpected disconnect occurred
 * _CAM_BDR_SENT_ - BUS DEVICE RESET message was sent to the target
 * _CAM_UNREC_HBA_ERROR_ - unrecoverable Host Bus Adapter Error
 * _CAM_REQ_TOO_BIG_ - the request was too large for this controller
 * _CAM_REQUEUE_REQ_ - this request should be re-queued to preserve transaction ordering. This typically occurs when the SIM recognizes an error that should freeze the queue and must place other queued requests for the target at the sim level back into the XPT queue. Typical cases of such errors are selection timeouts, command timeouts and other like conditions. In such cases the troublesome command returns the status indicating the error, the and the other commands which have not be sent to the bus yet get re-queued.
 * _CAM_LUN_INVALID_ - the LUN ID in the request is not supported by the SCSI controller
 * _CAM_TID_INVALID_ - the target ID in the request is not supported by the SCSI controller
 
 [[scsi-timeout]]
 == Timeout Handling
 
 When the timeout for an HCB expires that request should be aborted, just like with an XPT_ABORT request. The only difference is that the returned status of aborted request should be CAM_CMD_TIMEOUT instead of CAM_REQ_ABORTED (that is why implementation of the abort better be done as a function). But there is one more possible problem: what if the abort request itself will get stuck? In this case the SCSI bus should be reset, just like with an XPT_RESET_BUS request (and the idea about implementing it as a function called from both places applies here too). Also we should reset the whole SCSI bus if a device reset request got stuck. So after all the timeout function would look like:
 
 [.programlisting]
 ....
 static void
 xxx_timeout(void *arg)
 {
     struct xxx_hcb *hcb = (struct xxx_hcb *)arg;
     struct xxx_softc *softc;
     struct ccb_hdr *ccb_h;
 
     softc = hcb->softc;
     ccb_h = &hcb->ccb->ccb_h;
 
     if(hcb->flags & HCB_BEING_ABORTED
     || ccb_h->func_code == XPT_RESET_DEV) {
         xxx_reset_bus(softc);
     } else {
         xxx_abort_ccb(hcb->ccb, CAM_CMD_TIMEOUT);
     }
 }
 ....
 
 When we abort a request all the other disconnected requests to the same target/LUN get aborted too. So there appears a question, should we return them with status CAM_REQ_ABORTED or CAM_CMD_TIMEOUT? The current drivers use CAM_CMD_TIMEOUT. This seems logical because if one request got timed out then probably something really bad is happening to the device, so if they would not be disturbed they would time out by themselves.
diff --git a/documentation/content/en/books/arch-handbook/sound/_index.adoc b/documentation/content/en/books/arch-handbook/sound/_index.adoc
index 08510968e8..1b5dc08fc6 100644
--- a/documentation/content/en/books/arch-handbook/sound/_index.adoc
+++ b/documentation/content/en/books/arch-handbook/sound/_index.adoc
@@ -1,334 +1,334 @@
 ---
 title: Chapter 15. Sound Subsystem
 prev: books/arch-handbook/newbus
 next: books/arch-handbook/pccard
 description: FreeBSD Sound Subsystem
 tags: ["Sound", "OSS", "pcm", "mixer"]
 ---
 
 [[oss]]
 = Sound Subsystem
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 :outfilesuffix:
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 toc::[]
 
 [[oss-intro]]
 == Introduction
 
 The FreeBSD sound subsystem cleanly separates generic sound handling issues from device-specific ones. This makes it easier to add support for new hardware.
 
 The man:pcm[4] framework is the central piece of the sound subsystem. It mainly implements the following elements:
 
 * A system call interface (read, write, ioctls) to digitized sound and mixer functions. The ioctl command set is compatible with the legacy _OSS_ or _Voxware_ interface, allowing common multimedia applications to be ported without modification.
 * Common code for processing sound data (format conversions, virtual channels).
 * A uniform software interface to hardware-specific audio interface modules.
 * Additional support for some common hardware interfaces (ac97), or shared hardware-specific code (ex: ISA DMA routines).
 
 The support for specific sound cards is implemented by hardware-specific drivers, which provide channel and mixer interfaces to plug into the generic [.filename]#pcm# code.
 
 In this chapter, the term [.filename]#pcm# will refer to the central, common part of the sound driver, as opposed to the hardware-specific modules.
 
 The prospective driver writer will of course want to start from an existing module and use the code as the ultimate reference. But, while the sound code is nice and clean, it is also mostly devoid of comments. This document tries to give an overview of the framework interface and answer some questions that may arise while adapting the existing code.
 
 As an alternative, or in addition to starting from a working example, you can find a commented driver template at https://people.FreeBSD.org/~cg/template.c[ https://people.FreeBSD.org/~cg/template.c]
 
 [[oss-files]]
 == Files
 
 All the relevant code lives in [.filename]#/usr/src/sys/dev/sound/#, except for the public ioctl interface definitions, found in [.filename]#/usr/src/sys/sys/soundcard.h#
 
 Under [.filename]#/usr/src/sys/dev/sound/#, the [.filename]#pcm/# directory holds the central code, while the [.filename]#pci/#, [.filename]#isa/# and [.filename]#usb/# directories have the drivers for PCI and ISA boards, and for USB audio devices.
 
 [[pcm-probe-and-attach]]
 == Probing, Attaching, etc.
 
 Sound drivers probe and attach in almost the same way as any hardware driver module. You might want to look at the crossref:isa-driver[isa-driver,ISA] or crossref:pci[pci,PCI] specific sections of the handbook for more information.
 
 However, sound drivers differ in some ways:
 
 * They declare themselves as [.filename]#pcm# class devices, with a `struct snddev_info` device private structure:
 +
 [.programlisting]
 ....
           static driver_t xxx_driver = {
               "pcm",
               xxx_methods,
               sizeof(struct snddev_info)
           };
 
           DRIVER_MODULE(snd_xxxpci, pci, xxx_driver, pcm_devclass, 0, 0);
           MODULE_DEPEND(snd_xxxpci, snd_pcm, PCM_MINVER, PCM_PREFVER,PCM_MAXVER);
 ....
-+ 
++
 Most sound drivers  need to store additional private information about their device. A private data structure is usually allocated in the attach routine. Its address is passed to [.filename]#pcm# by the calls to `pcm_register()` and `mixer_init()`. [.filename]#pcm# later passes back this address as a parameter in calls to the sound driver interfaces.
 * The sound driver attach routine should declare its MIXER or AC97 interface to [.filename]#pcm# by calling `mixer_init()`. For a MIXER interface, this causes in turn a call to <<xxxmixer-init,`xxxmixer_init()`>>.
 * The sound driver attach routine declares its general CHANNEL configuration to [.filename]#pcm# by calling `pcm_register(dev, sc, nplay, nrec)`, where `sc` is the address for the device data structure, used in further calls from [.filename]#pcm#, and `nplay` and `nrec` are the number of play and record channels.
 * The sound driver attach routine declares each of its channel objects by calls to `pcm_addchan()`. This sets up the channel glue in [.filename]#pcm# and causes in turn a call to <<xxxchannel-init,`xxxchannel_init()`>>.
 * The sound driver detach routine should call `pcm_unregister()` before releasing its resources.
 
 There are two possible methods to handle non-PnP devices:
 
 * Use a `device_identify()` method (example: [.filename]#sound/isa/es1888.c#). The `device_identify()` method probes for the hardware at known addresses and, if it finds a supported device, creates a new pcm device which is then passed to probe/attach.
 * Use a custom kernel configuration with appropriate hints for pcm devices (example: [.filename]#sound/isa/mss.c#).
 
 [.filename]#pcm# drivers should implement `device_suspend`, `device_resume` and `device_shutdown` routines, so that power management and module unloading function correctly.
 
 [[oss-interfaces]]
 == Interfaces
 
 The interface between the [.filename]#pcm# core and the sound drivers is defined in terms of <<kernel-objects,kernel objects>>.
 
 There are two main interfaces that a sound driver will usually provide: _CHANNEL_ and either _MIXER_ or _AC97_.
 
 The _AC97_ interface is a very small hardware access (register read/write) interface, implemented by drivers for hardware with an AC97 codec. In this case, the actual MIXER interface is provided by the shared AC97 code in [.filename]#pcm#.
 
 === The CHANNEL Interface
 
 ==== Common Notes for Function Parameters
 
 Sound drivers usually have a private data structure to describe their device, and one structure for each play and record data channel that it supports.
 
 For all CHANNEL interface functions, the first parameter is an opaque pointer.
 
 The second parameter is a pointer to the private channel data structure, except for `channel_init()` which has a pointer to the private device structure (and returns the channel pointer for further use by [.filename]#pcm#).
 
 ==== Overview of Data Transfer Operations
 
 For sound data transfers, the [.filename]#pcm# core and the sound drivers communicate through a shared memory area, described by a `struct snd_dbuf`.
 
 `struct snd_dbuf` is private to [.filename]#pcm#, and sound drivers obtain values of interest by calls to accessor functions (`sndbuf_getxxx()`).
 
 The shared memory area has a size of `sndbuf_getsize()` and is divided into fixed size blocks of `sndbuf_getblksz()` bytes.
 
 When playing, the general transfer mechanism is as follows (reverse the idea for recording):
 
 * [.filename]#pcm# initially fills up the buffer, then calls the sound driver's <<channel-trigger,`xxxchannel_trigger()`>> function with a parameter of PCMTRIG_START.
 * The sound driver then arranges to repeatedly transfer the whole memory area (`sndbuf_getbuf()`, `sndbuf_getsize()`) to the device, in blocks of `sndbuf_getblksz()` bytes. It calls back the `chn_intr()`[.filename]#pcm# function for each transferred block (this will typically happen at interrupt time).
 * `chn_intr()` arranges to copy new data to the area that was transferred to the device (now free), and make appropriate updates to the `snd_dbuf` structure.
 
 [[xxxchannel-init]]
 ==== channel_init
 
 `xxxchannel_init()` is called to initialize each of the play or record channels. The calls are initiated from the sound driver attach routine. (See the <<pcm-probe-and-attach,probe and attach section>>).
 
 [.programlisting]
 ....
           static void *
           xxxchannel_init(kobj_t obj, void *data,
              struct snd_dbuf *b, struct pcm_channel *c, int dir) <.>
           {
               struct xxx_info *sc = data;
               struct xxx_chinfo *ch;
                ...
               return ch; <.>
            }
 ....
 
 <.> `b` is the address for the channel `struct snd_dbuf`. It should be initialized in the function by calling `sndbuf_alloc()`. The buffer size to use is normally a small multiple of the 'typical' unit transfer size for your device.`c` is the [.filename]#pcm# channel control structure pointer. This is an opaque object. The function should store it in the local channel structure, to be used in later calls to [.filename]#pcm# (ie: `chn_intr(c)`).`dir` indicates the channel direction (`PCMDIR_PLAY` or `PCMDIR_REC`).
 
 <.> The function should return a pointer to the private area used to control this channel. This will be passed as a parameter to other channel interface calls.
 
 ==== channel_setformat
 
 `xxxchannel_setformat()` should set up the hardware for the specified channel for the specified sound format.
 
 [.programlisting]
 ....
           static int
           xxxchannel_setformat(kobj_t obj, void *data, u_int32_t format) <.>
           {
               struct xxx_chinfo *ch = data;
                ...
               return 0;
            }
 ....
 
 <.> `format` is specified as an `AFMT_XXX value` ([.filename]#soundcard.h#).
 
 ==== channel_setspeed
 
 `xxxchannel_setspeed()` sets up the channel hardware for the specified sampling speed, and returns the possibly adjusted speed.
 
 [.programlisting]
 ....
           static int
           xxxchannel_setspeed(kobj_t obj, void *data, u_int32_t speed)
           {
               struct xxx_chinfo *ch = data;
                ...
               return speed;
            }
 ....
 
 ==== channel_setblocksize
 
 `xxxchannel_setblocksize()` sets the block size, which is the size of unit transactions between [.filename]#pcm# and the sound driver, and between the sound driver and the device. Typically, this would be the number of bytes transferred before an interrupt occurs. During a transfer, the sound driver should call [.filename]#pcm#'s `chn_intr()` every time this size has been transferred.
 
 Most sound drivers only take note of the block size here, to be used when an actual transfer will be started.
 
 [.programlisting]
 ....
           static int
           xxxchannel_setblocksize(kobj_t obj, void *data, u_int32_t blocksize)
           {
               struct xxx_chinfo *ch = data;
                 ...
               return blocksize; <.>
            }
 ....
 
 <.> The function returns the possibly adjusted block size. In case the block size is indeed changed, `sndbuf_resize()` should be called to adjust the buffer.
 
 [[channel-trigger]]
 ==== channel_trigger
 
 `xxxchannel_trigger()` is called by [.filename]#pcm# to control data transfer operations in the driver.
 
 [.programlisting]
 ....
           static int
           xxxchannel_trigger(kobj_t obj, void *data, int go) <.>
           {
               struct xxx_chinfo *ch = data;
                ...
               return 0;
            }
 ....
 
 <.> `go` defines the action for the current call. The possible values are:
 
 [NOTE]
 ====
 If the driver uses ISA DMA, `sndbuf_isadma()` should be called before performing actions on the device, and will take care of the DMA chip side of things.
 ====
 
 ==== channel_getptr
 
 `xxxchannel_getptr()` returns the current offset in the transfer buffer. This will typically be called by `chn_intr()`, and this is how [.filename]#pcm# knows where it can transfer new data.
 
 ==== channel_free
 
 `xxxchannel_free()` is called to free up channel resources, for example when the driver is unloaded, and should be implemented if the channel data structures are dynamically allocated or if `sndbuf_alloc()` was not used for buffer allocation.
 
 ==== channel_getcaps
 
 [.programlisting]
 ....
           struct pcmchan_caps *
           xxxchannel_getcaps(kobj_t obj, void *data)
           {
               return &xxx_caps; <.>
            }
 ....
 
 <.> The routine returns a pointer to a (usually statically-defined) `pcmchan_caps` structure (defined in [.filename]#sound/pcm/channel.h#. The structure holds the minimum and maximum sampling frequencies, and the accepted sound formats. Look at any sound driver for an example.
 
 ==== More Functions
 
 `channel_reset()`, `channel_resetdone()`, and `channel_notify()` are for special purposes and should not be implemented in a driver without discussing it on the {freebsd-multimedia}.
 
 `channel_setdir()` is deprecated.
 
 === The MIXER Interface
 
 [[xxxmixer-init]]
 ==== mixer_init
 
 `xxxmixer_init()` initializes the hardware and tells [.filename]#pcm# what mixer devices are available for playing and recording
 
 [.programlisting]
 ....
           static int
           xxxmixer_init(struct snd_mixer *m)
           {
               struct xxx_info   *sc = mix_getdevinfo(m);
               u_int32_t v;
 
               [Initialize hardware]
 
               [Set appropriate bits in v for play mixers] <.>
               mix_setdevs(m, v);
               [Set appropriate bits in v for record mixers]
               mix_setrecdevs(m, v)
 
               return 0;
           }
 ....
 
 <.> Set bits in an integer value and call `mix_setdevs()` and `mix_setrecdevs()` to tell [.filename]#pcm# what devices exist.
 
 Mixer bits definitions can be found in [.filename]#soundcard.h# (`SOUND_MASK_XXX` values and `SOUND_MIXER_XXX` bit shifts).
 
 ==== mixer_set
 
 `xxxmixer_set()` sets the volume level for one mixer device.
 
 [.programlisting]
 ....
           static int
           xxxmixer_set(struct snd_mixer *m, unsigned dev,
                            unsigned left, unsigned right) <.>
           {
               struct sc_info *sc = mix_getdevinfo(m);
               [set volume level]
               return left | (right << 8); <.>
           }
 ....
 
 <.> The device is specified as a `SOUND_MIXER_XXX` value. The volume values are specified in range [0-100]. A value of zero should mute the device.
 <.> As the hardware levels probably will not match the input scale, and some rounding will occur, the routine returns the actual level values (in range 0-100) as shown.
 
 ==== mixer_setrecsrc
 
 `xxxmixer_setrecsrc()` sets the recording source device.
 
 [.programlisting]
 ....
           static int
           xxxmixer_setrecsrc(struct snd_mixer *m, u_int32_t src) <.>
           {
               struct xxx_info *sc = mix_getdevinfo(m);
 
               [look for non zero bit(s) in src, set up hardware]
 
               [update src to reflect actual action]
               return src; <.>
            }
 ....
 
 <.> The desired recording devices are specified as a bit field
 <.> The actual devices set for recording are returned. Some drivers can only set one device for recording. The function should return -1 if an error occurs.
 
 ==== mixer_uninit, mixer_reinit
 
 `xxxmixer_uninit()` should ensure that all sound is muted and if possible mixer hardware should be powered down.
 
 `xxxmixer_reinit()` should ensure that the mixer hardware is powered up and any settings not controlled by `mixer_set()` or `mixer_setrecsrc()` are restored.
 
 === The AC97 Interface
 
 The _AC97_ interface is implemented by drivers with an AC97 codec. It only has three methods:
 
 * `xxxac97_init()` returns the number of ac97 codecs found.
 * `ac97_read()` and `ac97_write()` read or write a specified register.
 
 The _AC97_ interface is used by the AC97 code in [.filename]#pcm# to perform higher level operations. Look at [.filename]#sound/pci/maestro3.c# or many others under [.filename]#sound/pci/# for an example.
diff --git a/documentation/content/en/books/developers-handbook/ipv6/_index.adoc b/documentation/content/en/books/developers-handbook/ipv6/_index.adoc
index 9596e12e78..0abbcaa206 100644
--- a/documentation/content/en/books/developers-handbook/ipv6/_index.adoc
+++ b/documentation/content/en/books/developers-handbook/ipv6/_index.adoc
@@ -1,831 +1,831 @@
 ---
 title: Chapter 8. IPv6 Internals
 authors:
   - author: Yoshinobu Inoue
 prev: books/developers-handbook/sockets
 next: books/developers-handbook/partiii
 description: IPv6 Internals
 tags: ["IPv6", "FreeBSD"]
 ---
 
 [[ipv6]]
 = IPv6 Internals
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 8
 
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 toc::[]
 
 [[ipv6-implementation]]
 == IPv6/IPsec Implementation
 
 This section should explain IPv6 and IPsec related implementation internals.
 These functionalities are derived from http://www.kame.net/[KAME project]
 
 [[ipv6details]]
 === IPv6
 
 ==== Conformance
 
 The IPv6 related functions conforms, or tries to conform to the latest set of IPv6 specifications.
 For future reference we list some of the relevant documents below (_NOTE_: this is not a complete list - this is too hard to maintain...).
 
 For details please refer to specific chapter in the document, RFCs, manual pages, or comments in the source code.
 
 Conformance tests have been performed on the KAME STABLE kit at TAHI project.
 Results can be viewed at http://www.tahi.org/report/KAME/[http://www.tahi.org/report/KAME/].
 We also attended University of New Hampshire IOL tests (http://www.iol.unh.edu/[http://www.iol.unh.edu/]) in the past, with our past snapshots.
 
 * RFC1639: FTP Operation Over Big Address Records (FOOBAR)
 
 ** RFC2428 is preferred over RFC1639. FTP clients will first try RFC2428, then RFC1639 if failed.
 
 * RFC1886: DNS Extensions to support IPv6
 * RFC1933: Transition Mechanisms for IPv6 Hosts and Routers
 
 ** IPv4 compatible address is not supported.
 ** automatic tunneling (described in 4.3 of this RFC) is not supported.
 ** man:gif[4] interface implements IPv[46]-over-IPv[46] tunnel in a generic way, and it covers "configured tunnel" described in the spec. See <<gif,23.5.1.5>> in this document for details.
 
 * RFC1981: Path MTU Discovery for IPv6
 * RFC2080: RIPng for IPv6
 
 ** usr.sbin/route6d support this.
 
 * RFC2292: Advanced Sockets API for IPv6
 
 ** For supported library functions/kernel APIs, see [.filename]#sys/netinet6/ADVAPI#.
 
 * RFC2362: Protocol Independent Multicast-Sparse Mode (PIM-SM)
 
 ** RFC2362 defines packet formats for PIM-SM. [.filename]#draft-ietf-pim-ipv6-01.txt# is written based on this.
 
 * RFC2373: IPv6 Addressing Architecture
 
 ** supports node required addresses, and conforms to the scope requirement.
 
 * RFC2374: An IPv6 Aggregatable Global Unicast Address Format
 
 ** supports 64-bit length of Interface ID.
 
 * RFC2375: IPv6 Multicast Address Assignments
 
 ** Userland applications use the well-known addresses assigned in the RFC.
 
 * RFC2428: FTP Extensions for IPv6 and NATs
 
 ** RFC2428 is preferred over RFC1639. FTP clients will first try RFC2428, then RFC1639 if failed.
 
 * RFC2460: IPv6 specification
 * RFC2461: Neighbor discovery for IPv6
 
 ** See <<neighbor-discovery,23.5.1.2>> in this document for details.
 
 * RFC2462: IPv6 Stateless Address Autoconfiguration
 
 ** See <<ipv6-pnp,23.5.1.4>> in this document for details.
 
 * RFC2463: ICMPv6 for IPv6 specification
 
 ** See <<icmpv6,23.5.1.9>> in this document for details.
 
 * RFC2464: Transmission of IPv6 Packets over Ethernet Networks
 * RFC2465: MIB for IPv6: Textual Conventions and General Group
 
 ** Necessary statistics are gathered by the kernel. Actual IPv6 MIB support is provided as a patchkit for ucd-snmp.
 
 * RFC2466: MIB for IPv6: ICMPv6 group
 
 ** Necessary statistics are gathered by the kernel. Actual IPv6 MIB support is provided as patchkit for ucd-snmp.
 
 * RFC2467: Transmission of IPv6 Packets over FDDI Networks
 * RFC2497: Transmission of IPv6 packet over ARCnet Networks
 * RFC2553: Basic Socket Interface Extensions for IPv6
 
 ** IPv4 mapped address (3.7) and special behavior of IPv6 wildcard bind socket (3.8) are supported. See <<ipv6-wildcard-socket,23.5.1.12>> in this document for details.
 
 * RFC2675: IPv6 Jumbograms
 
 ** See <<ipv6-jumbo,23.5.1.7>> in this document for details.
 
 * RFC2710: Multicast Listener Discovery for IPv6
 * RFC2711: IPv6 router alert option
 * [.filename]#draft-ietf-ipngwg-router-renum-08#: Router renumbering for IPv6
 * [.filename]#draft-ietf-ipngwg-icmp-namelookups-02#: IPv6 Name Lookups Through ICMP
 * [.filename]#draft-ietf-ipngwg-icmp-name-lookups-03#: IPv6 Name Lookups Through ICMP
 * [.filename]#draft-ietf-pim-ipv6-01.txt#: PIM for IPv6
 
 ** man:pim6dd[8] implements dense mode. man:pim6sd[8] implements sparse mode.
 
 * [.filename]#draft-itojun-ipv6-tcp-to-anycast-00#: Disconnecting TCP connection toward IPv6 anycast address
 * [.filename]#draft-yamamoto-wideipv6-comm-model-00#
 
 ** See <<ipv6-sas,23.5.1.6>> in this document for details.
 
 * [.filename]#draft-ietf-ipngwg-scopedaddr-format-00.txt#: An Extension of Format for IPv6 Scoped Addresses
 
 [[neighbor-discovery]]
 ==== Neighbor Discovery
 
 Neighbor Discovery is fairly stable.
 Currently Address Resolution, Duplicated Address Detection, and Neighbor Unreachability Detection are supported.
 In the near future we will be adding Proxy Neighbor Advertisement support in the kernel and Unsolicited Neighbor Advertisement transmission command as admin tool.
 
 If DAD fails, the address will be marked "duplicated" and message will be generated to syslog (and usually to console).
 The "duplicated" mark can be checked with man:ifconfig[8].
 It is administrators' responsibility to check for and recover from DAD failures.
 The behavior should be improved in the near future.
 
 Some of the network driver loops multicast packets back to itself, even if instructed not to do so (especially in promiscuous mode).
 In such cases DAD may fail, because DAD engine sees inbound NS packet (actually from the node itself) and considers it as a sign of duplicate.
 You may want to look at #if condition marked "heuristics" in sys/netinet6/nd6_nbr.c:nd6_dad_timer() as workaround (note that the code fragment in "heuristics" section is not spec conformant).
 
 Neighbor Discovery specification (RFC2461) does not talk about neighbor cache handling in the following cases:
 
 . when there was no neighbor cache entry, node received unsolicited RS/NS/NA/redirect packet without link-layer address
 . neighbor cache handling on medium without link-layer address (we need a neighbor cache entry for IsRouter bit)
 
 For first case, we implemented workaround based on discussions on IETF ipngwg mailing list.
 For more details, see the comments in the source code and email thread started from (IPng 7155), dated Feb 6 1999.
 
 IPv6 on-link determination rule (RFC2461) is quite different from assumptions in BSD network code.
 At this moment, no on-link determination rule is supported where default router list is empty (RFC2461, section 5.2, last sentence in 2nd paragraph - note that the spec misuse the word "host" and "node" in several places in the section).
 
 To avoid possible DoS attacks and infinite loops, only 10 options on ND packet is accepted now.
 Therefore, if you have 20 prefix options attached to RA, only the first 10 prefixes will be recognized.
 If this troubles you, please ask it on FREEBSD-CURRENT mailing list and/or modify nd6_maxndopt in [.filename]#sys/netinet6/nd6.c#.
 If there are high demands we may provide sysctl knob for the variable.
 
 [[ipv6-scope-index]]
 ==== Scope Index
 
 IPv6 uses scoped addresses.
 Therefore, it is very important to specify scope index (interface index for link-local address, or site index for site-local address) with an IPv6 address.
 Without scope index, scoped IPv6 address is ambiguous to the kernel, and kernel will not be able to determine the outbound interface for a packet.
 
 Ordinary userland applications should use advanced API (RFC2292) to specify scope index, or interface index.
 For similar purpose, sin6_scope_id member in sockaddr_in6 structure is defined in RFC2553.
 However, the semantics for sin6_scope_id is rather vague.
 If you care about portability of your application, we suggest you to use advanced API rather than sin6_scope_id.
 
 In the kernel, an interface index for link-local scoped address is embedded into 2nd 16bit-word (3rd and 4th byte) in IPv6 address.
 For example, you may see something like:
 
 [source,bash]
 ....
 	fe80:1::200:f8ff:fe01:6317
 ....
 
 in the routing table and interface address structure (struct in6_ifaddr).
 The address above is a link-local unicast address which belongs to a network interface whose interface identifier is 1.
 The embedded index enables us to identify IPv6 link local addresses over multiple interfaces effectively and with only a little code change.
 
 Routing daemons and configuration programs, like man:route6d[8] and man:ifconfig[8], will need to manipulate the "embedded" scope index.
 These programs use routing sockets and ioctls (like SIOCGIFADDR_IN6) and the kernel API will return IPv6 addresses with 2nd 16bit-word filled in.
 The APIs are for manipulating kernel internal structure.
 Programs that use these APIs have to be prepared about differences in kernels anyway.
 
 When you specify scoped address to the command line, NEVER write the embedded form (such as ff02:1::1 or fe80:2::fedc).
 This is not supposed to work.
 Always use standard form, like ff02::1 or fe80::fedc, with command line option for specifying interface (like `ping6 -I ne0 ff02::1`).
 In general, if a command does not have command line option to specify outgoing interface, that command is not ready to accept scoped address.
 This may seem to be opposite from IPv6's premise to support "dentist office" situation.
 We believe that specifications need some improvements for this.
 
 Some of the userland tools support extended numeric IPv6 syntax, as documented in [.filename]#draft-ietf-ipngwg-scopedaddr-format-00.txt#.
 You can specify outgoing link, by using name of the outgoing interface like "fe80::1%ne0".
 This way you will be able to specify link-local scoped address without much trouble.
 
 To use this extension in your program, you will need to use man:getaddrinfo[3], and man:getnameinfo[3] with NI_WITHSCOPEID.
 The implementation currently assumes 1-to-1 relationship between a link and an interface, which is stronger than what specs say.
 
 [[ipv6-pnp]]
 ==== Plug and Play
 
 Most of the IPv6 stateless address autoconfiguration is implemented in the kernel.
 Neighbor Discovery functions are implemented in the kernel as a whole.
 Router Advertisement (RA) input for hosts is implemented in the kernel.
 Router Solicitation (RS) output for endhosts, RS input for routers, and RA output for routers are implemented in the userland.
 
 ===== Assignment of link-local, and special addresses
 
 IPv6 link-local address is generated from IEEE802 address (Ethernet MAC address).
 Each of interface is assigned an IPv6 link-local address automatically, when the interface becomes up (IFF_UP).
 Also, direct route for the link-local address is added to routing table.
 
 Here is an output of netstat command:
 
 [source,bash]
 ....
 Internet6:
 Destination                   Gateway                   Flags      Netif Expire
 fe80:1::%ed0/64               link#1                    UC          ed0
 fe80:2::%ep0/64               link#2                    UC          ep0
 ....
 
 Interfaces that has no IEEE802 address (pseudo interfaces like tunnel interfaces, or ppp interfaces) will borrow IEEE802 address from other interfaces, such as Ethernet interfaces, whenever possible.
 If there is no IEEE802 hardware attached, a last resort pseudo-random value, MD5(hostname), will be used as source of link-local address.
 If it is not suitable for your usage, you will need to configure the link-local address manually.
 
 If an interface is not capable of handling IPv6 (such as lack of multicast support), link-local address will not be assigned to that interface.
 See section 2 for details.
 
 Each interface joins the solicited multicast address and the link-local all-nodes multicast addresses (e.g., fe80::1:ff01:6317 and ff02::1, respectively, on the link the interface is attached).
 In addition to a link-local address, the loopback address (::1) will be assigned to the loopback interface.
 Also, ::1/128 and ff01::/32 are automatically added to routing table, and loopback interface joins node-local multicast group ff01::1.
 
 ===== Stateless address autoconfiguration on Hosts
 
 In IPv6 specification, nodes are separated into two categories: _routers_ and _hosts_.
 Routers forward packets addressed to others, hosts does not forward the packets. net.inet6.ip6.forwarding defines whether this node is router or host (router if it is 1, host if it is 0).
 
 When a host hears Router Advertisement from the router, a host may autoconfigure itself by stateless address autoconfiguration.
 This behavior can be controlled by net.inet6.ip6.accept_rtadv (host autoconfigures itself if it is set to 1).
 By autoconfiguration, network address prefix for the receiving interface (usually global address prefix) is added.
 Default route is also configured. Routers periodically generate Router Advertisement packets.
 To request an adjacent router to generate RA packet, a host can transmit Router Solicitation.
 To generate a RS packet at any time, use the _rtsol_ command. man:rtsold[8] daemon is also available.
 man:rtsold[8] generates Router Solicitation whenever necessary, and it works great for nomadic usage (notebooks/laptops).
 If one wishes to ignore Router Advertisements, use sysctl to set net.inet6.ip6.accept_rtadv to 0.
 
 To generate Router Advertisement from a router, use the man:rtadvd[8] daemon.
 
 Note that, IPv6 specification assumes the following items, and nonconforming cases are left unspecified:
 
 * Only hosts will listen to router advertisements
 * Hosts have single network interface (except loopback)
 
 Therefore, this is unwise to enable net.inet6.ip6.accept_rtadv on routers, or multi-interface host.
 A misconfigured node can behave strange (nonconforming configuration allowed for those who would like to do some experiments).
 
 To summarize the sysctl knob:
 
 [source,bash]
 ....
 	accept_rtadv	forwarding	role of the node
 	---		---		---
 	0		0		host (to be manually configured)
 	0		1		router
 	1		0		autoconfigured host
 					(spec assumes that host has single
 					interface only, autoconfigured host
 					with multiple interface is
 					out-of-scope)
 	1		1		invalid, or experimental
 					(out-of-scope of spec)
 ....
 
 RFC2462 has validation rule against incoming RA prefix information option, in 5.5.3 (e).
 This is to protect hosts from malicious (or misconfigured) routers that advertise very short prefix lifetime.
 There was an update from Jim Bound to ipngwg mailing list (look for "(ipng 6712)" in the archive) and it is implemented Jim's update.
 
 See <<neighbor-discovery,23.5.1.2>> in the document for relationship between DAD and autoconfiguration.
 
 [[gif]]
 ==== Generic Tunnel Interface
 
 GIF (Generic InterFace) is a pseudo interface for configured tunnel.
 Details are described in man:gif[4]. Currently
 
 * v6 in v6
 * v6 in v4
 * v4 in v6
 * v4 in v4
 
 are available. Use man:gifconfig[8] to assign physical (outer) source and destination address to gif interfaces.
 Configuration that uses same address family for inner and outer IP header (v4 in v4, or v6 in v6) is dangerous.
 It is very easy to configure interfaces and routing tables to perform infinite level of tunneling.
 _Please be warned_.
 
 gif can be configured to be ECN-friendly.
 See <<ipsec-ecn,23.5.4.5>> for ECN-friendliness of tunnels, and man:gif[4] for how to configure.
 
 If you would like to configure an IPv4-in-IPv6 tunnel with gif interface, read man:gif[4] carefully.
 You will need to remove IPv6 link-local address automatically assigned to the gif interface.
 
 [[ipv6-sas]]
 ==== Source Address Selection
 
 Current source selection rule is scope oriented (there are some exceptions - see below).
 For a given destination, a source IPv6 address is selected by the following rule:
 
 . If the source address is explicitly specified by the user (e.g., via the advanced API), the specified address is used.
 . If there is an address assigned to the outgoing interface (which is usually determined by looking up the routing table) that has the same scope as the destination address, the address is used.
-+ 
++
 This is the most typical case.
 . If there is no address that satisfies the above condition, choose a global address assigned to one of the interfaces on the sending node.
 . If there is no address that satisfies the above condition, and destination address is site local scope, choose a site local address assigned to one of the interfaces on the sending node.
 . If there is no address that satisfies the above condition, choose the address associated with the routing table entry for the destination. This is the last resort, which may cause scope violation.
 
 For instance, ::1 is selected for ff01::1, fe80:1::200:f8ff:fe01:6317 for fe80:1::2a0:24ff:feab:839b (note that embedded interface index - described in <<ipv6-scope-index,23.5.1.3>> - helps us choose the right source address.
 Those embedded indices will not be on the wire).
 If the outgoing interface has multiple address for the scope, a source is selected longest match basis (rule 3).
 Suppose 2001:0DB8:808:1:200:f8ff:fe01:6317 and 2001:0DB8:9:124:200:f8ff:fe01:6317 are given to the outgoing interface. 2001:0DB8:808:1:200:f8ff:fe01:6317 is chosen as the source for the destination 2001:0DB8:800::1.
 
 Note that the above rule is not documented in the IPv6 spec. It is considered "up to implementation" item.
 There are some cases where we do not use the above rule.
 One example is connected TCP session, and we use the address kept in tcb as the source.
 Another example is source address for Neighbor Advertisement.
 Under the spec (RFC2461 7.2.2) NA's source should be the target address of the corresponding NS's target.
 In this case we follow the spec rather than the above longest-match rule.
 
 For new connections (when rule 1 does not apply), deprecated addresses (addresses with preferred lifetime = 0) will not be chosen as source address if other choices are available.
 If no other choices are available, deprecated address will be used as a last resort.
 If there are multiple choice of deprecated addresses, the above scope rule will be used to choose from those deprecated addresses.
 If you would like to prohibit the use of deprecated address for some reason, configure net.inet6.ip6.use_deprecated to 0.
 The issue related to deprecated address is described in RFC2462 5.5.4 (NOTE: there is some debate underway in IETF ipngwg on how to use "deprecated" address).
 
 [[ipv6-jumbo]]
 ==== Jumbo Payload
 
 The Jumbo Payload hop-by-hop option is implemented and can be used to send IPv6 packets with payloads longer than 65,535 octets.
 But currently no physical interface whose MTU is more than 65,535 is supported, so such payloads can be seen only on the loopback interface (i.e., lo0).
 
 If you want to try jumbo payloads, you first have to reconfigure the kernel so that the MTU of the loopback interface is more than 65,535 bytes; add the following to the kernel configuration file:
 
 `options "LARGE_LOMTU" #To test jumbo payload`
 
 and recompile the new kernel.
 
 Then you can test jumbo payloads by the man:ping6[8] command with -b and -s options.
 The -b option must be specified to enlarge the size of the socket buffer and the -s option specifies the length of the packet, which should be more than 65,535.
 For example, type as follows:
 
 [source,bash]
 ....
 % ping6 -b 70000 -s 68000 ::1
 ....
 
 The IPv6 specification requires that the Jumbo Payload option must not be used in a packet that carries a fragment header.
 If this condition is broken, an ICMPv6 Parameter Problem message must be sent to the sender.
 specification is followed, but you cannot usually see an ICMPv6 error caused by this requirement.
 
 When an IPv6 packet is received, the frame length is checked and compared to the length specified in the payload length field of the IPv6 header or in the value of the Jumbo Payload option, if any.
 If the former is shorter than the latter, the packet is discarded and statistics are incremented.
 You can see the statistics as output of man:netstat[8] command with `-s -p ip6' option:
 
 [source,bash]
 ....
 % netstat -s -p ip6
 	  ip6:
 		(snip)
 		1 with data size < data length
 ....
 
 So, kernel does not send an ICMPv6 error unless the erroneous packet is an actual Jumbo Payload, that is, its packet size is more than 65,535 bytes.
 As described above, currently no physical interface with such a huge MTU is supported, so it rarely returns an ICMPv6 error.
 
 TCP/UDP over jumbogram is not supported at this moment.
 This is because we have no medium (other than loopback) to test this. Contact us if you need this.
 
 IPsec does not work on jumbograms.
 This is due to some specification twists in supporting AH with jumbograms (AH header size influences payload length, and this makes it real hard to authenticate inbound packet with jumbo payload option as well as AH).
 
 There are fundamental issues in *BSD support for jumbograms.
 We would like to address those, but we need more time to finalize these.
 To name a few:
 
 * mbuf pkthdr.len field is typed as "int" in 4.4BSD, so it will not hold jumbogram with len > 2G on 32bit architecture CPUs.
 If we would like to support jumbogram properly, the field must be expanded to hold 4G + IPv6 header + link-layer header.
 Therefore, it must be expanded to at least int64_t (u_int32_t is NOT enough).
 
 * We mistakingly use "int" to hold packet length in many places. We need to convert them into larger integral type. It needs a great care, as we may experience overflow during packet length computation.
 * We mistakingly check for ip6_plen field of IPv6 header for packet payload length in various places. We should be checking mbuf pkthdr.len instead. ip6_input() will perform sanity check on jumbo payload option on input, and we can safely use mbuf pkthdr.len afterwards.
 * TCP code needs a careful update in bunch of places, of course.
 
 ==== Loop Prevention in Header Processing
 
 IPv6 specification allows arbitrary number of extension headers to be placed onto packets.
 If we implement IPv6 packet processing code in the way BSD IPv4 code is implemented, kernel stack may overflow due to long function call chain.
 sys/netinet6 code is carefully designed to avoid kernel stack overflow, so sys/netinet6 code defines its own protocol switch structure, as "struct ip6protosw" (see [.filename]#netinet6/ip6protosw.h#).
 There is no such update to IPv4 part (sys/netinet) for compatibility, but small change is added to its pr_input() prototype.
 So "struct ipprotosw" is also defined.
 As a result, if you receive IPsec-over-IPv4 packet with massive number of IPsec headers, kernel stack may blow up.
 IPsec-over-IPv6 is okay.
 (Of-course, for those all IPsec headers to be processed, each such IPsec header must pass each IPsec check.
 So an anonymous attacker will not be able to do such an attack.)
 
 [[icmpv6]]
 ==== ICMPv6
 
 After RFC2463 was published, IETF ipngwg has decided to disallow ICMPv6 error packet against ICMPv6 redirect, to prevent ICMPv6 storm on a network medium.
 This is already implemented into the kernel.
 
 ==== Applications
 
 For userland programming, we support IPv6 socket API as specified in RFC2553, RFC2292 and upcoming Internet drafts.
 
 TCP/UDP over IPv6 is available and quite stable.
 You can enjoy man:telnet[1], man:ftp[1], man:rlogin[1], man:rsh[1], man:ssh[1], etc.
 These applications are protocol independent.
 That is, they automatically chooses IPv4 or IPv6 according to DNS.
 
 ==== Kernel Internals
 
 While ip_forward() calls ip_output(), ip6_forward() directly calls if_output() since routers must not divide IPv6 packets into fragments.
 
 ICMPv6 should contain the original packet as long as possible up to 1280.
 UDP6/IP6 port unreach, for instance, should contain all extension headers and the *unchanged* UDP6 and IP6 headers.
 So, all IP6 functions except TCP never convert network byte order into host byte order, to save the original packet.
 
 tcp_input(), udp6_input() and icmp6_input() can not assume that IP6 header is preceding the transport headers due to extension headers.
 So, in6_cksum() was implemented to handle packets whose IP6 header and transport header is not continuous.
 TCP/IP6 nor UDP6/IP6 header structures do not exist for checksum calculation.
 
 To process IP6 header, extension headers and transport headers easily, network drivers are now required to store packets in one internal mbuf or one or more external mbufs.
 A typical old driver prepares two internal mbufs for 96 - 204 bytes data, however, now such packet data is stored in one external mbuf.
 
 `netstat -s -p ip6` tells you whether or not your driver conforms such requirement.
 In the following example, "cce0" violates the requirement.
 (For more information, refer to Section 2.)
 
 [source,bash]
 ....
 Mbuf statistics:
                 317 one mbuf
                 two or more mbuf::
                         lo0 = 8
 			cce0 = 10
                 3282 one ext mbuf
                 0 two or more ext mbuf
 ....
 
 Each input function calls IP6_EXTHDR_CHECK in the beginning to check if the region between IP6 and its header is continuous.
 IP6_EXTHDR_CHECK calls m_pullup() only if the mbuf has M_LOOP flag, that is, the packet comes from the loopback interface.
 m_pullup() is never called for packets coming from physical network interfaces.
 
 Both IP and IP6 reassemble functions never call m_pullup().
 
 [[ipv6-wildcard-socket]]
 ==== IPv4 Mapped Address and IPv6 Wildcard Socket
 
 RFC2553 describes IPv4 mapped address (3.7) and special behavior of IPv6 wildcard bind socket (3.8).
 The spec allows you to:
 
 * Accept IPv4 connections by AF_INET6 wildcard bind socket.
 * Transmit IPv4 packet over AF_INET6 socket by using special form of the address like ::ffff:10.1.1.1.
 
 but the spec itself is very complicated and does not specify how the socket layer should behave.
 Here we call the former one "listening side" and the latter one "initiating side", for reference purposes.
 
 You can perform wildcard bind on both of the address families, on the same port.
 
 The following table show the behavior of FreeBSD 4.x.
 
 [source,bash]
 ....
 listening side          initiating side
                 (AF_INET6 wildcard      (connection to ::ffff:10.1.1.1)
                 socket gets IPv4 conn.)
                 ---                     ---
 FreeBSD 4.x     configurable            supported
                 default: enabled
 ....
 
 The following sections will give you more details, and how you can configure the behavior.
 
 Comments on listening side:
 
 It looks that RFC2553 talks too little on wildcard bind issue, especially on the port space issue, failure mode and relationship between AF_INET/INET6 wildcard bind.
 There can be several separate interpretation for this RFC which conform to it but behaves differently.
 So, to implement portable application you should assume nothing about the behavior in the kernel.
 Using man:getaddrinfo[3] is the safest way.
 Port number space and wildcard bind issues were discussed in detail on ipv6imp mailing list, in mid March 1999 and it looks that there is no concrete consensus (means, up to implementers).
 You may want to check the mailing list archives.
 
 If a server application would like to accept IPv4 and IPv6 connections, there will be two alternatives.
 
 One is using AF_INET and AF_INET6 socket (you will need two sockets).
 Use man:getaddrinfo[3] with AI_PASSIVE into ai_flags, and man:socket[2] and man:bind[2] to all the addresses returned.
 By opening multiple sockets, you can accept connections onto the socket with proper address family.
 IPv4 connections will be accepted by AF_INET socket, and IPv6 connections will be accepted by AF_INET6 socket.
 
 Another way is using one AF_INET6 wildcard bind socket.
 Use man:getaddrinfo[3] with AI_PASSIVE into ai_flags and with AF_INET6 into ai_family, and set the 1st argument hostname to NULL.
 And man:socket[2] and man:bind[2] to the address returned.
 (should be IPv6 unspecified addr).
 You can accept either of IPv4 and IPv6 packet via this one socket.
 
 To support only IPv6 traffic on AF_INET6 wildcard binded socket portably, always check the peer address when a connection is made toward AF_INET6 listening socket.
 If the address is IPv4 mapped address, you may want to reject the connection.
 You can check the condition by using IN6_IS_ADDR_V4MAPPED() macro.
 
 To resolve this issue more easily, there is system dependent man:setsockopt[2] option, IPV6_BINDV6ONLY, used like below.
 
 [.programlisting]
 ....
 	int on;
 
 	setsockopt(s, IPPROTO_IPV6, IPV6_BINDV6ONLY,
 		   (char *)&on, sizeof (on)) < 0));
 ....
 
 When this call succeed, then this socket only receive IPv6 packets.
 
 Comments on initiating side:
 
 Advise to application implementers: to implement a portable IPv6 application (which works on multiple IPv6 kernels), we believe that the following is the key to the success:
 
 * NEVER hardcode AF_INET nor AF_INET6.
 * Use man:getaddrinfo[3] and man:getnameinfo[3] throughout the system. Never use gethostby*(), getaddrby*(), inet_*() or getipnodeby*(). (To update existing applications to be IPv6 aware easily, sometime getipnodeby*() will be useful. But if possible, try to rewrite the code to use man:getaddrinfo[3] and man:getnameinfo[3].)
 * If you would like to connect to destination, use man:getaddrinfo[3] and try all the destination returned, like man:telnet[1] does.
 * Some of the IPv6 stack is shipped with buggy man:getaddrinfo[3]. Ship a minimal working version with your application and use that as last resort.
 
 If you would like to use AF_INET6 socket for both IPv4 and IPv6 outgoing connection, you will need to use man:getipnodebyname[3].
 When you would like to update your existing application to be IPv6 aware with minimal effort, this approach might be chosen.
 But please note that it is a temporal solution, because man:getipnodebyname[3] itself is not recommended as it does not handle scoped IPv6 addresses at all.
 For IPv6 name resolution, man:getaddrinfo[3] is the preferred API.
 So you should rewrite your application to use man:getaddrinfo[3], when you get the time to do it.
 
 When writing applications that make outgoing connections, story goes much simpler if you treat AF_INET and AF_INET6 as totally separate address family.
 {set,get}sockopt issue goes simpler, DNS issue will be made simpler.
 We do not recommend you to rely upon IPv4 mapped address.
 
 ===== unified tcp and inpcb code
 
 FreeBSD 4.x uses shared tcp code between IPv4 and IPv6 (from sys/netinet/tcp*) and separate udp4/6 code.
 It uses unified inpcb structure.
 
 The platform can be configured to support IPv4 mapped address.
 Kernel configuration is summarized as follows:
 
 * By default, AF_INET6 socket will grab IPv4 connections in certain condition, and can initiate connection to IPv4 destination embedded in IPv4 mapped IPv6 address.
 * You can disable it on entire system with sysctl like below.
-+ 
++
 `sysctl net.inet6.ip6.mapped_addr=0`
 
 ====== Listening Side
 
 Each socket can be configured to support special AF_INET6 wildcard bind (enabled by default).
 You can disable it on each socket basis with man:setsockopt[2] like below.
 
 [.programlisting]
 ....
 	int on;
 
 	setsockopt(s, IPPROTO_IPV6, IPV6_BINDV6ONLY,
 		   (char *)&on, sizeof (on)) < 0));
 ....
 
 Wildcard AF_INET6 socket grabs IPv4 connection if and only if the following conditions are satisfied:
 
 * there is no AF_INET socket that matches the IPv4 connection
 * the AF_INET6 socket is configured to accept IPv4 traffic, i.e., getsockopt(IPV6_BINDV6ONLY) returns 0.
 
 There is no problem with open/close ordering.
 
 ====== Initiating Side
 
 FreeBSD 4.x supports outgoing connection to IPv4 mapped address (::ffff:10.1.1.1), if the node is configured to support IPv4 mapped address.
 
 ==== sockaddr_storage
 
 When RFC2553 was about to be finalized, there was discussion on how struct sockaddr_storage members are named.
 One proposal is to prepend "__" to the members (like "__ss_len") as they should not be touched.
 The other proposal was not to prepend it (like "ss_len") as we need to touch those members directly.
 There was no clear consensus on it.
 
 As a result, RFC2553 defines struct sockaddr_storage as follows:
 
 [.programlisting]
 ....
 	struct sockaddr_storage {
 		u_char	__ss_len;	/* address length */
 		u_char	__ss_family;	/* address family */
 		/* and bunch of padding */
 	};
 ....
 
 On the contrary, XNET draft defines as follows:
 
 [.programlisting]
 ....
 	struct sockaddr_storage {
 		u_char	ss_len;		/* address length */
 		u_char	ss_family;	/* address family */
 		/* and bunch of padding */
 	};
 ....
 
 In December 1999, it was agreed that RFC2553bis should pick the latter (XNET) definition.
 
 Current implementation conforms to XNET definition, based on RFC2553bis discussion.
 
 If you look at multiple IPv6 implementations, you will be able to see both definitions.
 As an userland programmer, the most portable way of dealing with it is to:
 
 . ensure ss_family and/or ss_len are available on the platform, by using GNU autoconf,
 . have -Dss_family=__ss_family to unify all occurrences (including header file) into __ss_family, or
 . never touch __ss_family. cast to sockaddr * and use sa_family like:
 +
 [.programlisting]
 ....
 	struct sockaddr_storage ss;
 	family = ((struct sockaddr *)&ss)->sa_family
 ....
 
 === Network Drivers
 
 Now following two items are required to be supported by standard drivers:
 
 . mbuf clustering requirement. In this stable release, we changed MINCLSIZE into MHLEN+1 for all the operating systems in order to make all the drivers behave as we expect.
 . multicast. If man:ifmcstat[8] yields no multicast group for a interface, that interface has to be patched.
 
 If any of the drivers do not support the requirements, then the drivers cannot be used for IPv6 and/or IPsec communication.
 If you find any problem with your card using IPv6/IPsec, then, please report it to the {freebsd-bugs}.
 
 (NOTE: In the past we required all PCMCIA drivers to have a call to in6_ifattach().
 We have no such requirement any more)
 
 === Translator
 
 We categorize IPv4/IPv6 translator into 4 types:
 
 * _Translator A_ --- It is used in the early stage of transition to make it possible to establish a connection from an IPv6 host in an IPv6 island to an IPv4 host in the IPv4 ocean.
 * _Translator B_ --- It is used in the early stage of transition to make it possible to establish a connection from an IPv4 host in the IPv4 ocean to an IPv6 host in an IPv6 island.
 * _Translator C_ --- It is used in the late stage of transition to make it possible to establish a connection from an IPv4 host in an IPv4 island to an IPv6 host in the IPv6 ocean.
 * _Translator D_ --- It is used in the late stage of transition to make it possible to establish a connection from an IPv6 host in the IPv6 ocean to an IPv4 host in an IPv4 island.
 
 [[ipsec-implementation]]
 === IPsec
 
 IPsec is mainly organized by three components.
 
 . Policy Management
 . Key Management
 . AH and ESP handling
 
 ==== Policy Management
 
 The kernel implements experimental policy management code.
 There are two way to manage security policy.
 One is to configure per-socket policy using man:setsockopt[2].
 In this cases, policy configuration is described in man:ipsec_set_policy[3].
 The other is to configure kernel packet filter-based policy using PF_KEY interface, via man:setkey[8].
 
 The policy entry is not re-ordered with its indexes, so the order of entry when you add is very significant.
 
 ==== Key Management
 
 The key management code implemented in this kit (sys/netkey) is a home-brew PFKEY v2 implementation.
 This conforms to RFC2367.
 
 The home-brew IKE daemon, "racoon" is included in the kit (kame/kame/racoon).
 Basically you will need to run racoon as daemon, then set up a policy to require keys (like `ping -P 'out ipsec esp/transport//use'`).
 The kernel will contact racoon daemon as necessary to exchange keys.
 
 ==== AH and ESP Handling
 
 IPsec module is implemented as "hooks" to the standard IPv4/IPv6 processing.
 When sending a packet, ip{,6}_output() checks if ESP/AH processing is required by checking if a matching SPD (Security Policy Database) is found.
 If ESP/AH is needed, {esp,ah}{4,6}_output() will be called and mbuf will be updated accordingly.
 When a packet is received, {esp,ah}4_input() will be called based on protocol number, i.e., (*inetsw[proto])().
 {esp,ah}4_input() will decrypt/check authenticity of the packet, and strips off daisy-chained header and padding for ESP/AH.
 It is safe to strip off the ESP/AH header on packet reception, since we will never use the received packet in "as is" form.
 
 By using ESP/AH, TCP4/6 effective data segment size will be affected by extra daisy-chained headers inserted by ESP/AH.
 Our code takes care of the case.
 
 Basic crypto functions can be found in directory "sys/crypto".
 ESP/AH transform are listed in {esp,ah}_core.c with wrapper functions.
 If you wish to add some algorithm, add wrapper function in {esp,ah}_core.c, and add your crypto algorithm code into sys/crypto.
 
 Tunnel mode is partially supported in this release, with the following restrictions:
 
 * IPsec tunnel is not combined with GIF generic tunneling interface. It needs a great care because we may create an infinite loop between ip_output() and tunnelifp->if_output(). Opinion varies if it is better to unify them, or not.
 * MTU and Don't Fragment bit (IPv4) considerations need more checking, but basically works fine.
 * Authentication model for AH tunnel must be revisited. We will need to improve the policy management engine, eventually.
 
 ==== Conformance to RFCs and IDs
 
 The IPsec code in the kernel conforms (or, tries to conform) to the following standards:
 
 "old IPsec" specification documented in [.filename]#rfc182[5-9].txt#
 
 "new IPsec" specification documented in [.filename]#rfc240[1-6].txt#, [.filename]#rfc241[01].txt#, [.filename]#rfc2451.txt# and [.filename]#draft-mcdonald-simple-ipsec-api-01.txt# (draft expired, but you can take from link:ftp://ftp.kame.net/pub/internet-drafts/[ ftp://ftp.kame.net/pub/internet-drafts/]).
 (NOTE: IKE specifications, [.filename]#rfc241[7-9].txt# are implemented in userland, as "racoon" IKE daemon)
 
 Currently supported algorithms are:
 
 * old IPsec AH
 
 ** null crypto checksum (no document, just for debugging)
 ** keyed MD5 with 128bit crypto checksum ([.filename]#rfc1828.txt#)
 ** keyed SHA1 with 128bit crypto checksum (no document)
 ** HMAC MD5 with 128bit crypto checksum ([.filename]#rfc2085.txt#)
 ** HMAC SHA1 with 128bit crypto checksum (no document)
 
 * old IPsec ESP
 
 ** null encryption (no document, similar to [.filename]#rfc2410.txt#)
 ** DES-CBC mode ([.filename]#rfc1829.txt#)
 
 * new IPsec AH
 
 ** null crypto checksum (no document, just for debugging)
 ** keyed MD5 with 96bit crypto checksum (no document)
 ** keyed SHA1 with 96bit crypto checksum (no document)
 ** HMAC MD5 with 96bit crypto checksum ([.filename]#rfc2403.txt#)
 ** HMAC SHA1 with 96bit crypto checksum ([.filename]#rfc2404.txt#)
 
 * new IPsec ESP
 
 ** null encryption ([.filename]#rfc2410.txt#)
 ** DES-CBC with derived IV ([.filename]#draft-ietf-ipsec-ciph-des-derived-01.txt#, draft expired)
 ** DES-CBC with explicit IV ([.filename]#rfc2405.txt#)
 ** 3DES-CBC with explicit IV ([.filename]#rfc2451.txt#)
 ** BLOWFISH CBC ([.filename]#rfc2451.txt#)
 ** CAST128 CBC ([.filename]#rfc2451.txt#)
 ** RC5 CBC ([.filename]#rfc2451.txt#)
 ** each of the above can be combined with:
 
 *** ESP authentication with HMAC-MD5(96bit)
 *** ESP authentication with HMAC-SHA1(96bit)
 
 The following algorithms are NOT supported:
 
 * old IPsec AH
 
 ** HMAC MD5 with 128bit crypto checksum + 64bit replay prevention ([.filename]#rfc2085.txt#)
 ** keyed SHA1 with 160bit crypto checksum + 32bit padding ([.filename]#rfc1852.txt#)
 
 IPsec (in kernel) and IKE (in userland as "racoon") has been tested at several interoperability test events, and it is known to interoperate with many other implementations well.
 Also, current IPsec implementation as quite wide coverage for IPsec crypto algorithms documented in RFC (we cover algorithms without intellectual property issues only).
 
 [[ipsec-ecn]]
 ==== ECN Consideration on IPsec Tunnels
 
 ECN-friendly IPsec tunnel is supported as described in [.filename]#draft-ipsec-ecn-00.txt#.
 
 Normal IPsec tunnel is described in RFC2401.
 On encapsulation, IPv4 TOS field (or, IPv6 traffic class field) will be copied from inner IP header to outer IP header.
 On decapsulation outer IP header will be simply dropped.
 The decapsulation rule is not compatible with ECN, since ECN bit on the outer IP TOS/traffic class field will be lost.
 
 To make IPsec tunnel ECN-friendly, we should modify encapsulation and decapsulation procedure.
 This is described in http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt[ http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt], chapter 3.
 
 IPsec tunnel implementation can give you three behaviors, by setting net.inet.ipsec.ecn (or net.inet6.ipsec6.ecn) to some value:
 
 * RFC2401: no consideration for ECN (sysctl value -1)
 * ECN forbidden (sysctl value 0)
 * ECN allowed (sysctl value 1)
 
 Note that the behavior is configurable in per-node manner, not per-SA manner (draft-ipsec-ecn-00 wants per-SA configuration, but it looks too much for me).
 
 The behavior is summarized as follows (see source code for more detail):
 
 [source,bash]
 ....
 encapsulate                     decapsulate
                 ---                             ---
 RFC2401         copy all TOS bits               drop TOS bits on outer
                 from inner to outer.            (use inner TOS bits as is)
 
 ECN forbidden   copy TOS bits except for ECN    drop TOS bits on outer
                 (masked with 0xfc) from inner   (use inner TOS bits as is)
                 to outer.  set ECN bits to 0.
 
 ECN allowed     copy TOS bits except for ECN    use inner TOS bits with some
                 CE (masked with 0xfe) from      change.  if outer ECN CE bit
                 inner to outer.                 is 1, enable ECN CE bit on
                 set ECN CE bit to 0.            the inner.
 ....
 
 General strategy for configuration is as follows:
 
 * if both IPsec tunnel endpoint are capable of ECN-friendly behavior, you should better configure both end to "ECN allowed" (sysctl value 1).
 * if the other end is very strict about TOS bit, use "RFC2401" (sysctl value -1).
 * in other cases, use "ECN forbidden" (sysctl value 0).
 
 The default behavior is "ECN forbidden" (sysctl value 0).
 
 For more information, please refer to:
 
 http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt[ http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt], RFC2481 (Explicit Congestion Notification), src/sys/netinet6/{ah,esp}_input.c
 
 (Thanks goes to Kenjiro Cho mailto:kjc@csl.sony.co.jp[kjc@csl.sony.co.jp] for detailed analysis)
 
 ==== Interoperability
 
 Here are (some of) platforms that KAME code have tested IPsec/IKE interoperability in the past.
 Note that both ends may have modified their implementation, so use the following list just for reference purposes.
 
 Altiga, Ashley-laurent (vpcom.com), Data Fellows (F-Secure), Ericsson ACC, FreeS/WAN, HITACHI, IBM AIX(R), IIJ, Intel, Microsoft(R) Windows NT(R), NIST (linux IPsec + plutoplus), Netscreen, OpenBSD, RedCreek, Routerware, SSH, Secure Computing, Soliton, Toshiba, VPNet, Yamaha RT100i
diff --git a/documentation/content/en/books/developers-handbook/policies/_index.adoc b/documentation/content/en/books/developers-handbook/policies/_index.adoc
index f6d3a44cba..b08ed72832 100644
--- a/documentation/content/en/books/developers-handbook/policies/_index.adoc
+++ b/documentation/content/en/books/developers-handbook/policies/_index.adoc
@@ -1,316 +1,316 @@
 ---
 title: Chapter 5. Source Tree Guidelines and Policies
 authors:
   - author: Poul-Henning Kamp
   - author: Giorgos Keramidas
 prev: books/developers-handbook/l10n
 next: books/developers-handbook/testing
 description: Source Tree Guidelines and Policies
 tags: ["Style Guidelines", "MAINTAINER", "Makefiles", "Contributed Software", "Shared libraries"]
 ---
 
 [[policies]]
 = Source Tree Guidelines and Policies
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 toc::[]
 
 This chapter documents various guidelines and policies in force for the FreeBSD source tree.
 
 [[policies-style]]
 == Style Guidelines
 
 Consistent coding style is extremely important, particularly with large projects like FreeBSD.
 Code should follow the FreeBSD coding styles described in man:style[9] and man:style.Makefile[5].
 
 [[policies-maintainer]]
 == `MAINTAINER` on Makefiles
 
 If a particular portion of the FreeBSD [.filename]#src/# distribution is being maintained by a person or group of persons, this is communicated through an entry in [.filename]#src/MAINTAINERS#.
 Maintainers of ports within the Ports Collection express their maintainership to the world by adding a `MAINTAINER` line to the [.filename]#Makefile# of the port in question:
 
 [.programlisting]
 ....
 MAINTAINER= email-addresses
 ....
 
 [TIP]
 ====
 For other parts of the repository, or for sections not listed as having a maintainer, or when you are unsure who the active maintainer is, try looking at the recent commit history of the relevant parts of the source tree.
 It is quite often the case that a maintainer is not explicitly named, but the people who are actively working in a part of the source tree for, say, the last couple of years are interested in reviewing changes.
 Even if this is not specifically mentioned in the documentation or the source itself, asking for a review as a form of courtesy is a very reasonable thing to do.
 ====
 
 The role of the maintainer is as follows:
 
 * The maintainer owns and is responsible for that code. This means that he or she is responsible for fixing bugs and answering problem reports pertaining to that piece of the code, and in the case of contributed software, for tracking new versions, as appropriate.
 * Changes to directories which have a maintainer defined shall be sent to the maintainer for review before being committed. Only if the maintainer does not respond for an unacceptable period of time, to several emails, will it be acceptable to commit changes without review by the maintainer. However, it is suggested that you try to have the changes reviewed by someone else if at all possible.
 * It is of course not acceptable to add a person or group as maintainer unless they agree to assume this duty. On the other hand it does not have to be a committer and it can easily be a group of people.
 
 [[policies-contributed]]
 == Contributed Software
 
 Some parts of the FreeBSD distribution consist of software that is actively being maintained outside the FreeBSD project.
 For historical reasons, we call this _contributed_ software.
 Some examples are sendmail, gcc and patch.
 
 Over the last couple of years, various methods have been used in dealing with this type of software and all have some number of advantages and drawbacks.
 No clear winner has emerged.
 
 Since this is the case, after some debate one of these methods has been selected as the "official" method and will be required for future imports of software of this kind.
 Furthermore, it is strongly suggested that existing contributed software converge on this model over time, as it has significant advantages over the old method, including the ability to easily obtain diffs relative to the "official" versions of the source by everyone (even without direct repository access).
 This will make it significantly easier to return changes to the primary developers of the contributed software.
 
 Ultimately, however, it comes down to the people actually doing the work.
 If using this model is particularly unsuited to the package being dealt with, exceptions to these rules may be granted only with the approval of the core team and with the general consensus of the other developers.
 The ability to maintain the package in the future will be a key issue in the decisions.
 
 [NOTE]
 ====
 Because it makes it harder to import future versions minor, trivial and/or cosmetic changes are _strongly discouraged_ on files that are still tracking the vendor branch.
 ====
 
 [[vendor-import-svn]]
 === Vendor Imports with SVN
 
 This section describes the vendor import procedure with Subversion in details.
 
 [.procedure]
 . *Preparing the Tree*
-+ 
++
 If this is your first import after the switch to SVN, you will have to flatten and clean up the vendor tree, and bootstrap merge history in the main tree.
 If not, you can safely omit this step.
-+ 
++
 During the conversion from CVS to SVN, vendor branches were imported with the same layout as the main tree.
 For example, the foo vendor sources ended up in [.filename]#vendor/foo/dist/contrib/foo#, but it is pointless and rather inconvenient.
 What we really want is to have the vendor source directly in [.filename]#vendor/foo/dist#, like this:
 +
 [source,bash]
 ....
 % cd vendor/foo/dist/contrib/foo
 % svn move $(svn list) ../..
 % cd ../..
 % svn remove contrib
 % svn propdel -R svn:mergeinfo
 % svn commit
 ....
-+ 
++
 Note that, the `propdel` bit is necessary because starting with 1.5, Subversion will automatically add `svn:mergeinfo` to any directory you copy or move.
 In this case, you will not need this information, since you are not going to merge anything from the tree you deleted.
 +
 [NOTE]
 ====
 You may want to flatten the tags as well.
 The procedure is exactly the same.
 If you do this, put off the commit until the end.
 ====
-+ 
++
 Check the [.filename]#dist# tree and perform any cleanup that is deemed to be necessary.
 You may want to disable keyword expansion, as it makes no sense on unmodified vendor code.
 In some cases, it can be even be harmful.
 +
 [source,bash]
 ....
 % svn propdel svn:keywords -R .
 % svn commit
 ....
-+ 
++
 Bootstrapping of `svn:mergeinfo` on the target directory (in the main tree) to the revision that corresponds to the last change was made to the vendor tree prior to importing new sources is also needed:
 +
 [source,bash]
 ....
 % cd head/contrib/foo
 % svn merge --record-only ^/vendor/foo/dist@12345678 .
 % svn commit
 ....
-+ 
++
 With some shells, the `^` in the above command may need to be escaped with a backslash.
 . *Importing New Sources*
-+ 
++
 Prepare a full, clean tree of the vendor sources.
 With SVN, we can keep a full distribution in the vendor tree without bloating the main tree.
 Import everything but merge only what is needed.
-+ 
++
 Note that you will need to add any files that were added since the last vendor import, and remove any that were removed.
 To facilitate this, you should prepare sorted lists of the contents of the vendor tree and of the sources you are about to import:
 +
 [source,bash]
 ....
 % cd vendor/foo/dist
 % svn list -R | grep -v '/$' | sort > ../old
 % cd ../foo-9.9
 % find . -type f | cut -c 3- | sort > ../new
 ....
-+ 
++
 With these two files, the following command will list removed files (files only in [.filename]#old#):
 +
 [source,bash]
 ....
 % comm -23 ../old ../new
 ....
-+ 
++
 While the command below will list added files (files only in [.filename]#new#):
 +
 [source,bash]
 ....
 % comm -13 ../old ../new
 ....
-+ 
++
 Let us put this together:
 +
 [source,bash]
 ....
 % cd vendor/foo/foo-9.9
 % tar cf - . | tar xf - -C ../dist
 % cd ../dist
 % comm -23 ../old ../new | xargs svn remove
 % comm -13 ../old ../new | xargs svn add
 ....
 +
 [WARNING]
 ====
 If there are new directories in the new distribution, the last command will fail.
 You will have to add the directories, and run it again.
 Conversely, if any directories were removed, you will have to remove them manually.
 ====
-+ 
++
 Check properties on any new files:
 
 ** All text files should have `svn:eol-style` set to `native`.
 ** All binary files should have `svn:mime-type` set to `application/octet-stream`, unless there is a more appropriate media type.
 ** Executable files should have `svn:executable` set to `*`.
 ** There should be no other properties on any file in the tree.
 +
 [NOTE]
 ====
 You are ready to commit, but you should first check the output of `svn stat` and `svn diff` to make sure everything is in order.
 ====
-+ 
++
 Once you have committed the new vendor release, you should tag it for future reference.
 The best and quickest way is to do it directly in the repository:
 +
 [source,bash]
 ....
 % svn copy ^/vendor/foo/dist svn_base/vendor/foo/9.9
 ....
-+ 
++
 To get the new tag, you can update your working copy of [.filename]#vendor/foo#.
 +
 [NOTE]
 ====
 If you choose to do the copy in the checkout instead, do not forget to remove the generated `svn:mergeinfo` as described above.
 ====
 
 . *Merging to __-HEAD__*
-+ 
++
 After you have prepared your import, it is time to merge.
 Option `--accept=postpone` tells SVN not to handle merge conflicts yet, because they will be taken care of manually:
 +
 [source,bash]
 ....
 % cd head/contrib/foo
 % svn update
 % svn merge --accept=postpone ^/vendor/foo/dist
 ....
-+ 
++
 Resolve any conflicts, and make sure that any files that were added or removed in the vendor tree have been properly added or removed in the main tree. It is always a good idea to check differences against the vendor branch:
 +
 [source,bash]
 ....
 % svn diff --no-diff-deleted --old=^/vendor/foo/dist --new=.
 ....
-+ 
++
 `--no-diff-deleted` tells SVN not to check files that are in the vendor tree but not in the main tree.
 +
 [NOTE]
 ====
 With SVN, there is no concept of on or off the vendor branch.
 If a file that previously had local modifications no longer does, just remove any left-over cruft, such as FreeBSD version tags,
 so it no longer shows up in diffs against the vendor tree.
 ====
-+ 
++
 If any changes are required for the world to build with the new sources, make them now - and test until you are satisfied that everything build and runs correctly.
 . *Commit*
-+ 
++
 Now, you are ready to commit.
 Make sure you get everything in one go.
 Ideally, you would have done all steps in a clean tree, in which case you can just commit from the top of that tree.
 That is the best way to avoid surprises.
 If you do it properly, the tree will move atomically from a consistent state with the old code to a consistent state with the new code.
 
 [[policies-encumbered]]
 == Encumbered Files
 
 It might occasionally be necessary to include an encumbered file in the FreeBSD source tree.
 For example, if a device requires a small piece of binary code to be loaded to it before the device will operate,
 and we do not have the source to that code, then the binary file is said to be encumbered.
 The following policies apply to including encumbered files in the FreeBSD source tree.
 
 . Any file which is interpreted or executed by the system CPU(s) and not in source format is encumbered.
 . Any file with a license more restrictive than BSD or GNU is encumbered.
 . A file which contains downloadable binary data for use by the hardware is not encumbered, unless (1) or (2) apply to it. It must be stored in an architecture neutral ASCII format (file2c or uuencoding is recommended).
 . Any encumbered file requires specific approval from the link:https://www.FreeBSD.org/administration/#t-core[Core Team] before it is added to the repository.
 . Encumbered files go in [.filename]#src/contrib# or [.filename]#src/sys/contrib#.
 . The entire module should be kept together. There is no point in splitting it, unless there is code-sharing with non-encumbered code.
 . Object files are named [.filename]#arch/filename.o.uu>#.
 . Kernel files:
 .. Should always be referenced in [.filename]#conf/files.*# (for build simplicity).
 .. Should always be in [.filename]#LINT#, but the link:https://www.FreeBSD.org/administration/#t-core[Core Team] decides per case if it should be commented out or not. The link:https://www.FreeBSD.org/administration/#t-core[Core Team] can, of course, change their minds later on.
 .. The _Release Engineer_ decides whether or not it goes into the release.
 
 . User-land files:
 .. The link:https://www.FreeBSD.org/administration/#t-core[Core team] decides if the code should be part of `make world`.
 .. The link:https://www.FreeBSD.org/administration/#t-re[Release Engineering] decides if it goes into the release.
 
 [[policies-shlib]]
 == Shared Libraries
 
 If you are adding shared library support to a port or other piece of software that does not have one, the version numbers should follow these rules.
 Generally, the resulting numbers will have nothing to do with the release version of the software.
 
 The three principles of shared library building are:
 
 * Start from `1.0`
 * If there is a change that is backwards compatible, bump minor number (note that ELF systems ignore the minor number)
 * If there is an incompatible change, bump major number
 
 For instance, added functions and bugfixes result in the minor version number being bumped, while deleted functions, changed function call syntax, etc. will force the major version number to change.
 
 Stick to version numbers of the form major.minor (`_x_._y_`).
 Our a.out dynamic linker does not handle version numbers of the form `_x_._y_._z_` well.
 Any version number after the `_y_` (i.e., the third digit) is totally ignored when comparing shared lib version numbers to decide which library to link with.
 Given two shared libraries that differ only in the "micro" revision, `ld.so` will link with the higher one.
 That is, if you link with [.filename]#libfoo.so.3.3.3#, the linker only records `3.3` in the headers, and will link with anything starting with `_libfoo.so.3_._(anything >= 3)_._(highest available)_`.
 
 [NOTE]
 ====
 `ld.so` will always use the highest "minor" revision.
 For instance, it will use [.filename]#libc.so.2.2# in preference to [.filename]#libc.so.2.0#, even if the program was initially linked with [.filename]#libc.so.2.0#.
 ====
 
 In addition, our ELF dynamic linker does not handle minor version numbers at all.
 However, one should still specify a major and minor version number as our [.filename]#Makefile#'s "do the right thing" based on the type of system.
 
 For non-port libraries, it is also our policy to change the shared library version number only once between releases.
 In addition, it is our policy to change the major shared library version number only once between major OS releases (i.e., from 6.0 to 7.0).
 When you make a change to a system library that requires the version number to be bumped, check the [.filename]#Makefile#'s commit logs.
 It is the responsibility of the committer to ensure that the first such change since the release will result in the shared library version number in the [.filename]#Makefile# to be updated, and any subsequent changes will not.
diff --git a/documentation/content/en/books/developers-handbook/testing/_index.adoc b/documentation/content/en/books/developers-handbook/testing/_index.adoc
index 95c5cab0e8..b74ad38914 100644
--- a/documentation/content/en/books/developers-handbook/testing/_index.adoc
+++ b/documentation/content/en/books/developers-handbook/testing/_index.adoc
@@ -1,183 +1,183 @@
 ---
 title: Chapter 6. Regression and Performance Testing
 authors:
 prev: books/developers-handbook/policies
 next: books/developers-handbook/partii
 description: Regression and Performance Testing
 tags: ["Regression", "Performance Testing", "Testing", "Tinderbox"]
 ---
 
 [[testing]]
 = Regression and Performance Testing
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 toc::[]
 
 Regression tests are used to exercise a particular bit of the system to check that it works as expected, and to make sure that old bugs are not reintroduced.
 
 The FreeBSD regression testing tools can be found in the FreeBSD source tree in the directory [.filename]#src/tools/regression#.
 
 [[testing-micro-benchmark]]
 == Micro Benchmark Checklist
 
 This section contains hints for doing proper micro-benchmarking on FreeBSD or of FreeBSD itself.
 
 It is not possible to use all of the suggestions below every single time, but the more used, the better the benchmark's ability to test small differences will be.
 
 * Disable APM and any other kind of clock fiddling (ACPI ?).
 * Run in single user mode. E.g., man:cron[8], and other daemons only add noise. The man:sshd[8] daemon can also cause problems. If ssh access is required during testing either disable the SSHv1 key regeneration, or kill the parent `sshd` daemon during the tests.
 * Do not run man:ntpd[8].
 * If man:syslog[3] events are generated, run man:syslogd[8] with an empty [.filename]#/etc/syslogd.conf#, otherwise, do not run it.
 * Minimize disk-I/O, avoid it entirely if possible.
 * Do not mount file systems that are not needed.
 * Mount [.filename]#/#, [.filename]#/usr#, and any other file system as read-only if possible. This removes atime updates to disk (etc.) from the I/O picture.
 * Reinitialize the read/write test file system with man:newfs[8] and populate it from a man:tar[1] or man:dump[8] file before every run. Unmount and mount it before starting the test. This results in a consistent file system layout. For a worldstone test this would apply to [.filename]#/usr/obj# (just reinitialize with `newfs` and mount). To get 100% reproducibility, populate the file system from a man:dd[1] file (i.e.: `dd if=myimage of=/dev/ad0s1h bs=1m`)
 * Use malloc backed or preloaded man:md[4] partitions.
 * Reboot between individual iterations of the test, this gives a more consistent state.
 * Remove all non-essential device drivers from the kernel. For instance if USB is not needed for the test, do not put USB in the kernel. Drivers which attach often have timeouts ticking away.
 * Unconfigure hardware that are not in use. Detach disks with man:atacontrol[8] and man:camcontrol[8] if the disks are not used for the test.
 * Do not configure the network unless it is being tested, or wait until after the test has been performed to ship the results off to another computer.
-+ 
++
 If the system must be connected to a public network, watch out for spikes of broadcast traffic. Even though it is hardly noticeable, it will take up CPU cycles. Multicast has similar caveats.
 * Put each file system on its own disk. This minimizes jitter from head-seek optimizations.
 * Minimize output to serial or VGA consoles. Running output into files gives less jitter. (Serial consoles easily become a bottleneck.) Do not touch keyboard while the test is running, even kbd:[space] or kbd:[back-space] shows up in the numbers.
 * Make sure the test is long enough, but not too long. If the test is too short, timestamping is a problem. If it is too long temperature changes and drift will affect the frequency of the quartz crystals in the computer. Rule of thumb: more than a minute, less than an hour.
 * Try to keep the temperature as stable as possible around the machine. This affects both quartz crystals and disk drive algorithms. To get real stable clock, consider stabilized clock injection. E.g., get a OCXO + PLL, inject output into clock circuits instead of motherboard xtal. Contact {phk} for more information about this.
 * Run the test at least 3 times but it is better to run more than 20 times both for "before" and "after" code. Try to interleave if possible (i.e.: do not run 20 times before then 20 times after), this makes it possible to spot environmental effects. Do not interleave 1:1, but 3:3, this makes it possible to spot interaction effects.
-+ 
++
 A good pattern is: `bababa{bbbaaa}*`.
 This gives hint after the first 1+1 runs (so it is possible to stop the test if it goes entirely the wrong way), a standard deviation after the first 3+3 (gives a good indication if it is going to be worth a long run) and trending and interaction numbers later on.
 * Use man:ministat[1] to see if the numbers are significant. Consider buying "Cartoon guide to statistics" ISBN: 0062731025, highly recommended, if you have forgotten or never learned about standard deviation and Student's T.
 * Do not use background man:fsck[8] unless the test is a benchmark of background `fsck`. Also, disable `background_fsck` in [.filename]#/etc/rc.conf# unless the benchmark is not started at least 60+"``fsck`` runtime" seconds after the boot, as man:rc[8] wakes up and checks if `fsck` needs to run on any file systems when background `fsck` is enabled. Likewise, make sure there are no snapshots lying around unless the benchmark is a test with snapshots.
 * If the benchmark show unexpected bad performance, check for things like high interrupt volume from an unexpected source. Some versions of ACPI have been reported to "misbehave" and generate excess interrupts. To help diagnose odd test results, take a few snapshots of `vmstat -i` and look for anything unusual.
 * Make sure to be careful about optimization parameters for kernel and userspace, likewise debugging. It is easy to let something slip through and realize later the test was not comparing the same thing.
 * Do not ever benchmark with the `WITNESS` and `INVARIANTS` kernel options enabled unless the test is interested to benchmarking those features. `WITNESS` can cause 400%+ drops in performance. Likewise, userspace man:malloc[3] parameters default differently in -CURRENT from the way they ship in production releases.
 
 [[testing-tinderbox]]
 == The FreeBSD Source Tinderbox
 
 The source Tinderbox consists of:
 
 * A build script, [.filename]#tinderbox#, that automates checking out a specific version of the FreeBSD source tree and building it.
 * A supervisor script, [.filename]#tbmaster#, that monitors individual Tinderbox instances, logs their output, and emails failure notices.
 * A CGI script named [.filename]#index.cgi# that reads a set of tbmaster logs and presents an easy-to-read HTML summary of them.
 * A set of build servers that continually test the tip of the most important FreeBSD code branches.
 * A webserver that keeps a complete set of Tinderbox logs and displays an up-to-date summary.
 
 The scripts are maintained and were developed by {des}, and are now written in Perl, a move on from their original incarnation as shell scripts.
 All scripts and configuration files are kept in https://www.freebsd.org/cgi/cvsweb.cgi/projects/tinderbox/[/projects/tinderbox/].
 
 For more information about the tinderbox and tbmaster scripts at this stage, see their respective man pages: tinderbox(1) and tbmaster(1).
 
 == The index.cgi Script
 
 The [.filename]#index.cgi# script generates the HTML summary of tinderbox and tbmaster logs.
 Although originally intended to be used as a CGI script, as indicated by its name,
 this script can also be run from the command line or from a man:cron[8] job, in which case it will look for logs in the directory where the script is located.
 It will automatically detect context, generating HTTP headers when it is run as a CGI script.
 It conforms to XHTML standards and is styled using CSS.
 
 The script starts in the `main()` block by attempting to verify that it is running on the official Tinderbox website.
 If it is not, a page indicating it is not an official website is produced, and a URL to the official site is provided.
 
 Next, it scans the log directory to get an inventory of configurations, branches and architectures for which log files exist, to avoid hard-coding a list into the script and potentially ending up with blank rows or columns.
 This information is derived from the names of the log files matching the following pattern:
 
 [.programlisting]
 ....
 tinderbox-$config-$branch-$arch-$machine.{brief,full}
 ....
 
 The configurations used on the official Tinderbox build servers are named for the branches they build.
 For example, the `releng_8` configuration is used to build `RELENG_8` as well as all still-supported release branches.
 
 Once all of this startup procedure has been successfully completed, `do_config()` is called for each configuration.
 
 The `do_config()` function generates HTML for a single Tinderbox configuration.
 
 It works by first generating a header row, then iterating over each branch build with the specified configuration,
 producing a single row of results for each in the following manner:
 
 * For each item:
 
 ** For each machine within that architecture:
 
 *** If a brief log file exists, then:
 
 **** Call `success()` to determine the outcome of the build.
 **** Output the modification size.
 **** Output the size of the brief log file with a link to the log file itself.
 **** If a full log file also exists, then:
 
 ***** Output the size of the full log file with a link to the log file itself.
 
 *** Otherwise:
 
 **** No output.
 
 The `success()` function mentioned above scans a brief log file for the string "tinderbox run completed" in order to determine whether the build was successful.
 
 Configurations and branches are sorted according to their branch rank.
 This is computed as follows:
 
 * `HEAD` and `CURRENT` have rank 9999.
 * `RELENG_x` has rank __``xx``__99.
 * `RELENG_x_y` has rank _xxyy_.
 
 This means that `HEAD` always ranks highest, and `RELENG` branches are ranked in numerical order, with each `STABLE` branch ranking higher than the release branches forked off of it.
 For instance, for FreeBSD 8, the order from highest to lowest would be:
 
 * `RELENG_8` (branch rank 899).
 * `RELENG_8_3` (branch rank 803).
 * `RELENG_8_2` (branch rank 802).
 * `RELENG_8_1` (branch rank 801).
 * `RELENG_8_0` (branch rank 800).
 
 The colors that Tinderbox uses for each cell in the table are defined by CSS.
 Successful builds are displayed with green text; unsuccessful builds are displayed with red text.
 The color fades as time passes since the corresponding build, with every half an hour bringing the color closer to grey.
 
 == Official Build Servers
 
 The official Tinderbox build servers are hosted by http://www.sentex.ca[Sentex Data Communications], who also host the FreeBSD Netperf Cluster.
 
 Three build servers currently exist:
 
 _freebsd-current.sentex.ca_ builds:
 
 * `HEAD` for amd64, arm, i386, i386/pc98, ia64, mips, powerpc, powerpc64, and sparc64.
 * `RELENG_9` and supported 9._X_ branches for amd64, arm, i386, i386/pc98, ia64, mips, powerpc, powerpc64, and sparc64.
 
 _freebsd-stable.sentex.ca_ builds:
 
 * `RELENG_8` and supported 8._X_ branches for amd64, i386, i386/pc98, ia64, mips, powerpc and sparc64.
 
 _freebsd-legacy.sentex.ca_ builds:
 
 * `RELENG_7` and supported 7._X_ branches for amd64, i386, i386/pc98, ia64, powerpc, and sparc64.
 
 == Official Summary Site
 
 Summaries and logs from the official build servers are available online at http://tinderbox.FreeBSD.org[http://tinderbox.FreeBSD.org], hosted by {des} and set up as follows:
 
 * A man:cron[8] job checks the build servers at regular intervals and downloads any new log files using man:rsync[1].
 * Apache is set up to use [.filename]#index.cgi# as `DirectoryIndex`.
diff --git a/documentation/content/en/books/developers-handbook/tools/_index.adoc b/documentation/content/en/books/developers-handbook/tools/_index.adoc
index d72fb6a590..ceecb30b2d 100644
--- a/documentation/content/en/books/developers-handbook/tools/_index.adoc
+++ b/documentation/content/en/books/developers-handbook/tools/_index.adoc
@@ -1,1710 +1,1710 @@
 ---
 title: Chapter 2. Programming Tools
 authors:
   - author: James Raynard
   - author: Murray Stokely
 prev: books/developers-handbook/introduction
 next: books/developers-handbook/secure
 description: Programming Tools
 tags: ["tools", "Interpreters", "Compilers", "cc", "make", "Debugging", "lldb", "gdb", "Emacs"]
 ---
 
 [[tools]]
 = Programming Tools
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 2
 :c-plus-plus-command: c++
 :clang-plus-plus-command: clang++
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[tools-synopsis]]
 == Synopsis
 
 This chapter is an introduction to using some of the programming tools supplied with FreeBSD,
 although much of it will be applicable to many other versions of UNIX(R).
 It does _not_ attempt to describe coding in any detail.
 Most of the chapter assumes little or no previous programming knowledge,
 although it is hoped that most programmers will find something of value in it.
 
 [[tools-intro]]
 == Introduction
 
 FreeBSD offers an excellent development environment.
 Compilers for C and C++ and an assembler come with the basic system, not to mention classic UNIX(R) tools such as `sed` and `awk`.
 If that is not enough, there are many more compilers and interpreters in the Ports collection.
 The following section, <<tools-programming,Introduction to Programming>>, lists some of the available options.
 FreeBSD is very compatible with standards such as POSIX(R) and ANSI C, as well with its own BSD heritage, so it is possible to write applications that will compile and run with little or no modification on a wide range of platforms.
 
 However, all this power can be rather overwhelming at first if you have never written programs on a UNIX(R) platform before.
 This document aims to help you get up and running, without getting too deeply into more advanced topics.
 The intention is that this document should give you enough of the basics to be able to make some sense of the documentation.
 
 Most of the document requires little or no knowledge of programming, although it does assume a basic competence with using UNIX(R) and a willingness to learn!
 
 [[tools-programming]]
 == Introduction to Programming
 
 A program is a set of instructions that tell the computer to do various things; sometimes the instruction it has to perform depends on what happened when it performed a previous instruction.
 This section gives an overview of the two main ways in which you can give these instructions, or "commands" as they are usually called.
 One way uses an _interpreter_, the other a _compiler_.
 As human languages are too difficult for a computer to understand in an unambiguous way, commands are usually written in one or other languages specially designed for the purpose.
 
 === Interpreters
 
 With an interpreter, the language comes as an environment, where you type in commands at a prompt and the environment executes them for you.
 For more complicated programs, you can type the commands into a file and get the interpreter to load the file and execute the commands in it.
 If anything goes wrong, many interpreters will drop you into a debugger to help you track down the problem.
 
 The advantage of this is that you can see the results of your commands immediately, and mistakes can be corrected readily.
 The biggest disadvantage comes when you want to share your programs with someone.
 They must have the same interpreter, or you must have some way of giving it to them, and they need to understand how to use it.
 Also users may not appreciate being thrown into a debugger if they press the wrong key! From a performance point of view, interpreters can use up a lot of memory, and generally do not generate code as efficiently as compilers.
 
 In my opinion, interpreted languages are the best way to start if you have not done any programming before.
 This kind of environment is typically found with languages like Lisp, Smalltalk, Perl and Basic.
 It could also be argued that the UNIX(R) shell (`sh`, `csh`) is itself an interpreter, and many people do in fact write shell "scripts" to help with various "housekeeping" tasks on their machine.
 Indeed, part of the original UNIX(R) philosophy was to provide lots of small utility programs that could be linked together in shell scripts to perform useful tasks.
 
 === Interpreters Available with FreeBSD
 
 Here is a list of interpreters that are available from the FreeBSD Ports Collection, with a brief discussion of some of the more popular interpreted languages.
 
 Instructions on how to get and install applications from the Ports Collection can be found in the link:{handbook}#ports-using/[Ports section] of the handbook.
 
 BASIC::
 Short for Beginner's All-purpose Symbolic Instruction Code.
 Developed in the 1950s for teaching University students to program and provided with every self-respecting personal computer in the 1980s, BASIC has been the first programming language for many programmers.
 It is also the foundation for Visual Basic.
 +
 The Bywater Basic Interpreter can be found in the Ports Collection as package:lang/bwbasic[] and the Phil Cockroft's Basic Interpreter (formerly Rabbit Basic) is available as package:lang/pbasic[].
 
 Lisp::
 A language that was developed in the late 1950s as an alternative to the "number-crunching" languages that were popular at the time.
 Instead of being based on numbers, Lisp is based on lists; in fact, the name is short for "List Processing".
 It is very popular in AI (Artificial Intelligence) circles.
 +
 Lisp is an extremely powerful and sophisticated language, but can be rather large and unwieldy.
 +
 Various implementations of Lisp that can run on UNIX(R) systems are available in the Ports Collection for FreeBSD.
 GNU Common Lisp can be found as package:lang/gcl[].
 CLISP by Bruno Haible and Michael Stoll is available as package:lang/clisp[].
 For CMUCL, which includes a highly-optimizing compiler too, or simpler Lisp implementations like SLisp, which implements most of the Common Lisp constructs in a few hundred lines of C code, package:lang/cmucl[] and package:lang/slisp[] are available respectively.
 
 Perl::
 Very popular with system administrators for writing scripts; also often used on World Wide Web servers for writing CGI scripts.
 +
 Perl is available in the Ports Collection as package:lang/perl5.24[] for all FreeBSD releases.
 
 Scheme::
 A dialect of Lisp that is rather more compact and cleaner than Common Lisp.
 Popular in Universities as it is simple enough to teach to undergraduates as a first language,
 while it has a high enough level of abstraction to be used in research work.
 +
 Scheme is available from the Ports Collection as package:lang/elk[] for the Elk Scheme Interpreter.
 The MIT Scheme Interpreter can be found in package:lang/mit-scheme[] and the SCM Scheme Interpreter in package:lang/scm[].
 
 Icon::
 Icon is a high-level language with extensive facilities for processing strings and structures.
 The version of Icon for FreeBSD can be found in the Ports Collection as package:lang/icon[].
 
 Logo::
 Logo is a language that is easy to learn, and has been used as an introductory programming language in various courses.
 It is an excellent tool to work with when teaching programming to smaller age groups, as it makes creation of elaborate geometric shapes an easy task.
 +
 The latest version of Logo for FreeBSD is available from the Ports Collection in package:lang/logo[].
 
 Python::
 Python is an Object-Oriented, interpreted language.
 Its advocates argue that it is one of the best languages to start programming with, since it is relatively easy to start with, but is not limited in comparison to other popular interpreted languages that are used for the development of large, complex applications (Perl and Tcl are two other languages that are popular for such tasks).
 +
 The latest version of Python is available from the Ports Collection in package:lang/python[].
 
 Ruby::
 Ruby is an interpreter, pure object-oriented programming language.
 It has become widely popular because of its easy to understand syntax, flexibility when writing code, and the ability to easily develop and maintain large, complex programs.
 +
 Ruby is available from the Ports Collection as package:lang/ruby25[].
 
 Tcl and Tk::
 Tcl is an embeddable, interpreted language, that has become widely used and became popular mostly because of its portability to many platforms.
 It can be used both for quickly writing small, prototype applications, or (when combined with Tk, a GUI toolkit) fully-fledged, featureful programs.
 +
 Various versions of Tcl are available as ports for FreeBSD.
 The latest version, Tcl 8.5, can be found in package:lang/tcl87[].
 
 === Compilers
 
 Compilers are rather different.
 First of all, you write your code in a file (or files) using an editor.
 You then run the compiler and see if it accepts your program.
 If it did not compile, grit your teeth and go back to the editor;
 if it did compile and gave you a program, you can run it either at a shell command prompt or in a debugger to see if it works properly.footnote:[If you run it in the shell, you may get a core dump.]
 
 Obviously, this is not quite as direct as using an interpreter.
 However it allows you to do a lot of things which are very difficult or even impossible with an interpreter,
 such as writing code which interacts closely with the operating system-or even writing your own operating system!
 It is also useful if you need to write very efficient code, as the compiler can take its time and optimize the code,
 which would not be acceptable in an interpreter.
 Moreover, distributing a program written for a compiler is usually more straightforward than one written for an interpreter-you can just give them a copy of the executable, assuming they have the same operating system as you.
 
 As the edit-compile-run-debug cycle is rather tedious when using separate programs, many commercial compiler makers have produced Integrated Development Environments (IDEs for short).
 FreeBSD does not include an IDE in the base system, but package:devel/kdevelop[] is available in the Ports Collection and many use Emacs for this purpose.
 Using Emacs as an IDE is discussed in <<emacs>>.
 
 [[tools-compiling]]
 == Compiling with `cc`
 
 This section deals with the gcc and clang compilers for C and C++, since they come with the FreeBSD base system.
 Starting with FreeBSD 10.X `clang` is installed as `cc`.
 The details of producing a program with an interpreter vary considerably between interpreters, and are usually well covered in the documentation and on-line help for the interpreter.
 
 Once you have written your masterpiece, the next step is to convert it into something that will (hopefully!) run on FreeBSD.
 This usually involves several steps, each of which is done by a separate program.
 
 [.procedure]
 . Pre-process your source code to remove comments and do other tricks like expanding macros in C.
 . Check the syntax of your code to see if you have obeyed the rules of the language. If you have not, it will complain!
 . Convert the source code into assembly language-this is very close to machine code, but still understandable by humans. Allegedly.
 . Convert the assembly language into machine code-yep, we are talking bits and bytes, ones and zeros here.
 . Check that you have used things like functions and global variables in a consistent way. For example, if you have called a non-existent function, it will complain.
 . If you are trying to produce an executable from several source code files, work out how to fit them all together.
 . Work out how to produce something that the system's run-time loader will be able to load into memory and run.
 . Finally, write the executable on the filesystem.
 
 The word _compiling_ is often used to refer to just steps 1 to 4-the others are referred to as _linking_.
 Sometimes step 1 is referred to as _pre-processing_ and steps 3-4 as _assembling_.
 
 Fortunately, almost all this detail is hidden from you, as `cc` is a front end that manages calling all these programs with the right arguments for you; simply typing
 
 [source,bash]
 ....
 % cc foobar.c
 ....
 
 will cause [.filename]#foobar.c# to be compiled by all the steps above.
 If you have more than one file to compile, just do something like
 
 [source,bash]
 ....
 % cc foo.c bar.c
 ....
 
 Note that the syntax checking is just that-checking the syntax.
 It will not check for any logical mistakes you may have made, like putting the program into an infinite loop,
 or using a bubble sort when you meant to use a binary sort.footnote:[In case you did not know, a binary sort is an efficient way of sorting things into order and a bubble sort is not.]
 
 There are lots and lots of options for `cc`, which are all in the manual page.
 Here are a few of the most important ones, with examples of how to use them.
 
 `-o _filename_`::
 The output name of the file. If you do not use this option, `cc` will produce an executable called [.filename]#a.out#.footnote:[The reasons for this are buried in the mists of history.]
 +
 [source,bash]
 ....
 % cc foobar.c               executable is a.out
 % cc -o foobar foobar.c     executable is foobar
 ....
 
 `-c`::
 Just compile the file, do not link it.
 Useful for toy programs where you just want to check the syntax, or if you are using a [.filename]#Makefile#.
 +
 [source,bash]
 ....
 % cc -c foobar.c
 ....
 +
 This will produce an _object file_ (not an executable) called [.filename]#foobar.o#.
 This can be linked together with other object files into an executable.
 
 `-g`::
 Create a debug version of the executable.
 This makes the compiler put information into the executable about which line of which source file corresponds to which function call.
 A debugger can use this information to show the source code as you step through the program, which is _very_ useful;
 the disadvantage is that all this extra information makes the program much bigger.
 Normally, you compile with `-g` while you are developing a program and then compile a "release version" without `-g` when you are satisfied it works properly.
 +
 
 [source,bash]
 ....
 % cc -g foobar.c
 ....
 +
 This will produce a debug version of the program. footnote:[Note, we did not use the -o flag to specify the executable name, so we will get an executable called a.out. Producing a debug version called foobar is left as an exercise for the reader!]
 
 `-O`::
 Create an optimized version of the executable.
 The compiler performs various clever tricks to try to produce an executable that runs faster than normal.
 You can add a number after the `-O` to specify a higher level of optimization, but this often exposes bugs in the compiler's optimizer.
 +
 [source,bash]
 ....
 % cc -O -o foobar foobar.c
 ....
 +
 This will produce an optimized version of [.filename]#foobar#.
 
 The following three flags will force `cc` to check that your code complies to the relevant international standard,
 often referred to as the ANSI standard, though strictly speaking it is an ISO standard.
 
 `-Wall`::
 Enable all the warnings which the authors of `cc` believe are worthwhile.
 Despite the name, it will not enable all the warnings `cc` is capable of.
 
 `-ansi`::
 Turn off most, but not all, of the non-ANSI C features provided by `cc`.
 Despite the name, it does not guarantee strictly that your code will comply to the standard.
 
 `-pedantic`::
 Turn off _all_ ``cc``'s non-ANSI C features.
 
 Without these flags, `cc` will allow you to use some of its non-standard extensions to the standard.
 Some of these are very useful, but will not work with other compilers-in fact,
 one of the main aims of the standard is to allow people to write code that will work with any compiler on any system.
 This is known as _portable code_.
 
 Generally, you should try to make your code as portable as possible,
 as otherwise you may have to completely rewrite the program later to get it to work somewhere else-and who knows what you may be using in a few years time?
 
 [source,bash]
 ....
 % cc -Wall -ansi -pedantic -o foobar foobar.c
 ....
 
 This will produce an executable [.filename]#foobar# after checking [.filename]#foobar.c# for standard compliance.
 
 `-l__library__`::
 Specify a function library to be used at link time.
 +
 The most common example of this is when compiling a program that uses some of the mathematical functions in C.
 Unlike most other platforms, these are in a separate library from the standard C one and you have to tell the compiler to add it.
 +
 The rule is that if the library is called [.filename]#libsomething.a#, you give `cc` the argument `-l__something__`.
 For example, the math library is [.filename]#libm.a#, so you give `cc` the argument `-lm`.
 A common "gotcha" with the math library is that it has to be the last library on the command line.
 +
 [source,bash]
 ....
 % cc -o foobar foobar.c -lm
 ....
 +
 This will link the math library functions into [.filename]#foobar#.
 +
 If you are compiling C++ code, use {c-plus-plus-command}.
 {c-plus-plus-command} can also be invoked as {clang-plus-plus-command} on FreeBSD.
 +
 [source,bash]
 ....
 % c++ -o foobar foobar.cc
 ....
 +
 This will both produce an executable [.filename]#foobar# from the C++ source file [.filename]#foobar.cc#.
 
 === Common `cc` Queries and Problems
 
 ==== I am trying to write a program which uses the sin() function and I get an error like this. What does it mean?
 
 [source,bash]
 ....
 /var/tmp/cc0143941.o: Undefined symbol `_sin' referenced from text segment
 ....
 
 When using mathematical functions like `sin()`, you have to tell `cc` to link in the math library, like so:
 
 [source,bash]
 ....
 % cc -o foobar foobar.c -lm
 ....
 
 ==== All right, I wrote this simple program to practice using -lm. All it does is raise 2.1 to the power of 6.
 
 [.programlisting]
 ....
 #include <stdio.h>
 
 int main() {
 	float f;
 
 	f = pow(2.1, 6);
 	printf("2.1 ^ 6 = %f\n", f);
 	return 0;
 }
 ....
 
 and I compiled it as:
 
 [source,bash]
 ....
 % cc temp.c -lm
 ....
 
 like you said I should, but I get this when I run it:
 
 [source,bash]
 ....
 % ./a.out
 2.1 ^ 6 = 1023.000000
 ....
 
 This is not the right answer! What is going on?
 
 When the compiler sees you call a function, it checks if it has already seen a prototype for it.
 If it has not, it assumes the function returns an int, which is definitely not what you want here.
 
 ==== So how do I fix this?
 
 The prototypes for the mathematical functions are in [.filename]#math.h#.
 If you include this file, the compiler will be able to find the prototype and it will stop doing strange things to your calculation!
 
 [.programlisting]
 ....
 #include <math.h>
 #include <stdio.h>
 
 int main() {
 ...
 ....
 
 After recompiling it as you did before, run it:
 
 [source,bash]
 ....
 % ./a.out
 2.1 ^ 6 = 85.766121
 ....
 
 If you are using any of the mathematical functions, _always_ include [.filename]#math.h# and remember to link in the math library.
 
 ==== I compiled a file called foobar.c and I cannot find an executable called foobar. Where has it gone?
 
 Remember, `cc` will call the executable [.filename]#a.out# unless you tell it differently.
 Use the `-o _filename_` option:
 
 [source,bash]
 ....
 % cc -o foobar foobar.c
 ....
 
 ==== OK, I have an executable called foobar, I can see it when I run ls, but when I type in foobar at the command prompt it tells me there is no such file. Why can it not find it?
 
 Unlike MS-DOS(R), UNIX(R) does not look in the current directory when it is trying to find out which executable you want it to run, unless you tell it to.
 Type `./foobar`, which means "run the file called [.filename]#foobar# in the current directory."
 
 === I called my executable test, but nothing happens when I run it. What is going on?
 
 Most UNIX(R) systems have a program called `test` in [.filename]#/usr/bin# and the shell is picking that one up before it gets to checking the current directory.
 Either type:
 
 [source,bash]
 ....
 % ./test
 ....
 
 or choose a better name for your program!
 
 ==== I compiled my program and it seemed to run all right at first, then there was an error and it said something about core dumped. What does that mean?
 
 The name _core dump_ dates back to the very early days of UNIX(R), when the machines used core memory for storing data.
 Basically, if the program failed under certain conditions, the system would write the contents of core memory to disk in a file called [.filename]#core#, which the programmer could then pore over to find out what went wrong.
 
 ==== Fascinating stuff, but what I am supposed to do now?
 
 Use a debugger to analyze the core (see <<debugging>>).
 
 ==== When my program dumped core, it said something about a segmentation fault. What is that?
 
 This basically means that your program tried to perform some sort of illegal operation on memory;
 UNIX(R) is designed to protect the operating system and other programs from rogue programs.
 
 Common causes for this are:
 
 * Trying to write to a NULL pointer, eg
 +
 [.programlisting]
 ....
 char *foo = NULL;
 strcpy(foo, "bang!");
 ....
 
 * Using a pointer that has not been initialized, eg
 +
 [.programlisting]
 ....
 char *foo;
 strcpy(foo, "bang!");
 ....
-+ 
++
 The pointer will have some random value that, with luck, will point into an area of memory that is not available to your program and the kernel will kill your program before it can do any damage.
 If you are unlucky, it will point somewhere inside your own program and corrupt one of your data structures, causing the program to fail mysteriously.
 * Trying to access past the end of an array, eg
 +
 [.programlisting]
 ....
 int bar[20];
 bar[27] = 6;
 ....
 
 * Trying to store something in read-only memory, eg
 +
 [.programlisting]
 ....
 char *foo = "My string";
 strcpy(foo, "bang!");
 ....
-+ 
++
 UNIX(R) compilers often put string literals like `"My string"` into read-only areas of memory.
 * Doing naughty things with `malloc()` and `free()`, eg
 +
 [.programlisting]
 ....
 char bar[80];
 free(bar);
 ....
-+ 
++
 or
 +
 [.programlisting]
 ....
 char *foo = malloc(27);
 free(foo);
 free(foo);
 ....
 
 Making one of these mistakes will not always lead to an error, but they are always bad practice.
 Some systems and compilers are more tolerant than others,
 which is why programs that ran well on one system can crash when you try them on an another.
 
 ==== Sometimes when I get a core dump it says bus error. It says in my UNIX(R) book that this means a hardware problem, but the computer still seems to be working. Is this true?
 
 No, fortunately not (unless of course you really do have a hardware problem...).
 This is usually another way of saying that you accessed memory in a way you should not have.
 
 ==== This dumping core business sounds as though it could be quite useful, if I can make it happen when I want to. Can I do this, or do I have to wait until there is an error?
 
 Yes, just go to another console or xterm, do
 
 [source,bash]
 ....
 % ps
 ....
 
 to find out the process ID of your program, and do
 
 [source,bash]
 ....
 % kill -ABRT pid
 ....
 
 where `_pid_` is the process ID you looked up.
 
 This is useful if your program has got stuck in an infinite loop, for instance.
 If your program happens to trap SIGABRT, there are several other signals which have a similar effect.
 
 Alternatively, you can create a core dump from inside your program, by calling the `abort()` function.
 See the manual page of man:abort[3] to learn more.
 
 If you want to create a core dump from outside your program, but do not want the process to terminate, you can use the `gcore` program.
 See the manual page of man:gcore[1] for more information.
 
 [[tools-make]]
 == Make
 
 === What is `make`?
 
 When you are working on a simple program with only one or two source files, typing in
 
 [source,bash]
 ....
 % cc file1.c file2.c
 ....
 
 is not too bad, but it quickly becomes very tedious when there are several files-and it can take a while to compile, too.
 
 One way to get around this is to use object files and only recompile the source file if the source code has changed.
 So we could have something like:
 
 [source,bash]
 ....
 % cc file1.o file2.o … file37.c …
 ....
 
 if we had changed [.filename]#file37.c#, but not any of the others, since the last time we compiled.
 This may speed up the compilation quite a bit, but does not solve the typing problem.
 
 Or we could write a shell script to solve the typing problem, but it would have to re-compile everything, making it very inefficient on a large project.
 
 What happens if we have hundreds of source files lying about? What if we are working in a team with other people who forget to tell us when they have changed one of their source files that we use?
 
 Perhaps we could put the two solutions together and write something like a shell script that would contain some kind of magic rule saying when a source file needs compiling.
 Now all we need now is a program that can understand these rules, as it is a bit too complicated for the shell.
 
 This program is called `make`.
 It reads in a file, called a _makefile_, that tells it how different files depend on each other, and works out which files need to be re-compiled and which ones do not.
 For example, a rule could say something like "if [.filename]#fromboz.o# is older than [.filename]#fromboz.c#, that means someone must have changed [.filename]#fromboz.c#, so it needs to be re-compiled."
 The makefile also has rules telling make _how_ to re-compile the source file, making it a much more powerful tool.
 
 Makefiles are typically kept in the same directory as the source they apply to, and can be called [.filename]#makefile#, [.filename]#Makefile# or [.filename]#MAKEFILE#.
 Most programmers use the name [.filename]#Makefile#, as this puts it near the top of a directory listing, where it can easily be seen.footnote:[They do not use the MAKEFILE form as block capitals are often used for documentation files like README.]
 
 === Example of Using `make`
 
 Here is a very simple make file:
 
 [.programlisting]
 ....
 foo: foo.c
 	cc -o foo foo.c
 ....
 
 It consists of two lines, a dependency line and a creation line.
 
 The dependency line here consists of the name of the program (known as the _target_),
 followed by a colon, then whitespace, then the name of the source file.
 When `make` reads this line, it looks to see if [.filename]#foo# exists;
 if it exists, it compares the time [.filename]#foo# was last modified to the time [.filename]#foo.c# was last modified.
 If [.filename]#foo# does not exist, or is older than [.filename]#foo.c#, it then looks at the creation line to find out what to do.
 In other words, this is the rule for working out when [.filename]#foo.c# needs to be re-compiled.
 
 The creation line starts with a tab (press kbd:[tab]) and then the command you would type to create [.filename]#foo# if you were doing it at a command prompt.
 If [.filename]#foo# is out of date, or does not exist, `make` then executes this command to create it.
 In other words, this is the rule which tells make how to re-compile [.filename]#foo.c#.
 
 So, when you type `make`, it will make sure that [.filename]#foo# is up to date with respect to your latest changes to [.filename]#foo.c#.
 This principle can be extended to [.filename]#Makefile#'s with hundreds of targets-in fact, on FreeBSD,
 it is possible to compile the entire operating system just by typing `make world` in the appropriate directory!
 
 Another useful property of makefiles is that the targets do not have to be programs.
 For instance, we could have a make file that looks like this:
 
 [.programlisting]
 ....
 foo: foo.c
 	cc -o foo foo.c
 
 install:
 	cp foo /home/me
 ....
 
 We can tell make which target we want to make by typing:
 
 [source,bash]
 ....
 % make target
 ....
 
 `make` will then only look at that target and ignore any others.
 For example, if we type `make foo` with the makefile above, make will ignore the `install` target.
 
 If we just type `make` on its own, make will always look at the first target and then stop without looking at any others.
 So if we typed `make` here, it will just go to the `foo` target, re-compile [.filename]#foo# if necessary, and then stop without going on to the `install` target.
 
 Notice that the `install` target does not actually depend on anything! This means that the command on the following line is always executed when we try to make that target by typing `make install`.
 In this case, it will copy [.filename]#foo# into the user's home directory.
 This is often used by application makefiles, so that the application can be installed in the correct directory when it has been correctly compiled.
 
 This is a slightly confusing subject to try to explain.
 If you do not quite understand how `make` works, the best thing to do is to write a simple program like "hello world" and a make file like the one above and experiment.
 Then progress to using more than one source file, or having the source file include a header file.
 `touch` is very useful here-it changes the date on a file without you having to edit it.
 
 === Make and include-files
 
 C code often starts with a list of files to include, for example stdio.h.
 Some of these files are system-include files, some of them are from the project you are now working on:
 
 [.programlisting]
 ....
 #include <stdio.h>
 #include "foo.h"
 
 int main(....
 ....
 
 To make sure that this file is recompiled the moment [.filename]#foo.h# is changed, you have to add it in your [.filename]#Makefile#:
 
 [.programlisting]
 ....
 foo: foo.c foo.h
 ....
 
 The moment your project is getting bigger and you have more and more own include-files to maintain,
 it will be a pain to keep track of all include files and the files which are depending on it.
 If you change an include-file but forget to recompile all the files which are depending on it,
 the results will be devastating.
 `clang` has an option to analyze your files and to produce a list of include-files and their dependencies: `-MM`.
 
 If you add this to your Makefile:
 
 [.programlisting]
 ....
 depend:
 	cc -E -MM *.c > .depend
 ....
 
 and run `make depend`, the file [.filename]#.depend# will appear with a list of object-files, C-files and the include-files:
 
 [.programlisting]
 ....
 foo.o: foo.c foo.h
 ....
 
 If you change [.filename]#foo.h#, next time you run `make` all files depending on [.filename]#foo.h# will be recompiled.
 
 Do not forget to run `make depend` each time you add an include-file to one of your files.
 
 === FreeBSD Makefiles
 
 Makefiles can be rather complicated to write.
 Fortunately, BSD-based systems like FreeBSD come with some very powerful ones as part of the system.
 One very good example of this is the FreeBSD ports system.
 Here is the essential part of a typical ports [.filename]#Makefile#:
 
 [.programlisting]
 ....
 MASTER_SITES=   ftp://freefall.cdrom.com/pub/FreeBSD/LOCAL_PORTS/
 DISTFILES=      scheme-microcode+dist-7.3-freebsd.tgz
 
 .include <bsd.port.mk>
 ....
 
 Now, if we go to the directory for this port and type `make`, the following happens:
 
 [.procedure]
 . A check is made to see if the source code for this port is already on the system.
 . If it is not, an FTP connection to the URL in MASTER_SITES is set up to download the source.
 . The checksum for the source is calculated and compared it with one for a known, good, copy of the source. This is to make sure that the source was not corrupted while in transit.
 . Any changes required to make the source work on FreeBSD are applied-this is known as _patching_.
 . Any special configuration needed for the source is done. (Many UNIX(R) program distributions try to work out which version of UNIX(R) they are being compiled on and which optional UNIX(R) features are present-this is where they are given the information in the FreeBSD ports scenario).
 . The source code for the program is compiled. In effect, we change to the directory where the source was unpacked and do `make`-the program's own make file has the necessary information to build the program.
 . We now have a compiled version of the program. If we wish, we can test it now; when we feel confident about the program, we can type `make install`. This will cause the program and any supporting files it needs to be copied into the correct location; an entry is also made into a `package database`, so that the port can easily be uninstalled later if we change our mind about it.
 
 Now I think you will agree that is rather impressive for a four line script!
 
 The secret lies in the last line, which tells `make` to look in the system makefile called [.filename]#bsd.port.mk#.
 It is easy to overlook this line, but this is where all the clever stuff comes from-someone has written a makefile that tells `make` to do all the things above (plus a couple of other things I did not mention,
 including handling any errors that may occur) and anyone can get access to that just by putting a single line in their own make file!
 
 If you want to have a look at these system makefiles, they are in [.filename]#/usr/share/mk#,
 but it is probably best to wait until you have had a bit of practice with makefiles,
 as they are very complicated (and if you do look at them, make sure you have a flask of strong coffee handy!)
 
 === More Advanced Uses of `make`
 
 `Make` is a very powerful tool, and can do much more than the simple example above shows.
 Unfortunately, there are several different versions of `make`, and they all differ considerably.
 The best way to learn what they can do is probably to read the documentation-hopefully this introduction will have given you a base from which you can do this.
 
 The version of make that comes with FreeBSD is the Berkeley make; there is a tutorial for it in [.filename]#/usr/share/doc/psd/12.make#.
 To view it, do
 
 [source,bash]
 ....
 % zmore paper.ascii.gz
 ....
 
 in that directory.
 
 Many applications in the ports use GNU make, which has a very good set of "info" pages.
 If you have installed any of these ports, GNU make will automatically have been installed as `gmake`.
 It is also available as a port and package in its own right.
 
 To view the info pages for GNU make, you will have to edit [.filename]#dir# in the [.filename]#/usr/local/info# directory to add an entry for it.
 This involves adding a line like
 
 [.programlisting]
 ....
  * Make: (make).                 The GNU Make utility.
 ....
 
 to the file. Once you have done this, you can type `info` and then select [.guimenuitem]#make# from the menu (or in Emacs, do `C-h i`).
 
 [[debugging]]
 == Debugging
 
 === Introduction to Available Debuggers
 
 Using a debugger allows running the program under more controlled circumstances.
 Typically, it is possible to step through the program a line at a time, inspect the value of variables, change them, tell the debugger to run up to a certain point and then stop, and so on.
 It is also possible to attach to a program that is already running, or load a core file to investigate why the program crashed.
 It is even possible to debug the kernel, though that is a little trickier than the user applications we will be discussing in this section.
 
 This section is intended to be a quick introduction to using debuggers and does not cover specialized topics such as debugging the kernel.
 For more information about that, refer to crossref:kerneldebug[kerneldebug,Kernel Debugging].
 
 The standard debugger supplied with FreeBSD {rel121-current} is called `lldb` (LLVM debugger).
 As it is part of the standard installation for that release, there is no need to do anything special to use it.
 It has good command help, accessible via the `help` command, as well as https://lldb.llvm.org/[a web tutorial and documentation].
 
 [NOTE]
 ====
 The `lldb` command is available for FreeBSD {rel113-current} link:{handbook}#ports-using/[from ports or packages] as package:devel/llvm[].
 This will install the default version of lldb (currently 9.0).
 ====
 
 The other debugger available with FreeBSD is called `gdb` (GNU debugger).
 Unlike lldb, it is not installed by default on FreeBSD {rel121-current};
 to use it, link:{handbook}#ports-using/[install] package:devel/gdb[] from ports or packages.
 The version installed by default on FreeBSD {rel113-current} is old; instead, install package:devel/gdb[] there as well.
 It has quite good on-line help, as well as a set of info pages.
 
 Which one to use is largely a matter of taste.
 If familiar with one only, use that one.
 People familiar with neither or both but wanting to use one from inside Emacs will need to use `gdb` as `lldb` is unsupported by Emacs.
 Otherwise, try both and see which one you prefer.
 
 === Using lldb
 
 ==== Starting lldb
 
 Start up lldb by typing
 
 [source,bash]
 ....
 % lldb -- progname
 ....
 
 ==== Running a Program with lldb
 
 Compile the program with `-g` to get the most out of using `lldb`.
 It will work without, but will only display the name of the function currently running, instead of the source code.
 If it displays a line like:
 
 [source,bash]
 ....
 Breakpoint 1: where = temp`main, address = …
 ....
 
 (without an indication of source code filename and line number) when setting a breakpoint, this means that the program was not compiled with `-g`.
 
 [TIP]
 ====
 Most `lldb` commands have shorter forms that can be used instead.
 The longer forms are used here for clarity.
 ====
 
 At the `lldb` prompt, type `breakpoint set -n main`.
 This will tell the debugger not to display the preliminary set-up code in the program being run and to stop execution at the beginning of the program's code.
 Now type `process launch` to actually start the program- it will start at the beginning of the set-up code and then get stopped by the debugger when it calls `main()`.
 
 To step through the program a line at a time, type `thread step-over`.
 When the program gets to a function call, step into it by typing `thread step-in`.
 Once in a function call, return from it by typing `thread step-out` or use `up` and `down` to take a quick look at the caller.
 
 Here is a simple example of how to spot a mistake in a program with `lldb`.
 This is our program (with a deliberate mistake):
 
 [.programlisting]
 ....
 #include <stdio.h>
 
 int bazz(int anint);
 
 main() {
 	int i;
 
 	printf("This is my program\n");
 	bazz(i);
 	return 0;
 }
 
 int bazz(int anint) {
 	printf("You gave me %d\n", anint);
 	return anint;
 }
 ....
 
 This program sets i to be `5` and passes it to a function `bazz()` which prints out the number we gave it.
 
 Compiling and running the program displays
 
 [source,bash]
 ....
 % cc -g -o temp temp.c
 % ./temp
 This is my program
 anint = -5360
 ....
 
 That is not what was expected! Time to see what is going on!
 
 [source,bash]
 ....
 % lldb -- temp
 (lldb) target create "temp"
 Current executable set to 'temp' (x86_64).
 (lldb) breakpoint set -n main				Skip the set-up code
 Breakpoint 1: where = temp`main + 15 at temp.c:8:2, address = 0x00000000002012ef	lldb puts breakpoint at main()
 (lldb) process launch					Run as far as main()
 Process 9992 launching
 Process 9992 launched: '/home/pauamma/tmp/temp' (x86_64)	Program starts running
 
 Process 9992 stopped
 * thread #1, name = 'temp', stop reason = breakpoint 1.1	lldb stops at main()
     frame #0: 0x00000000002012ef temp`main at temp.c:8:2
    5	main() {
    6		int i;
    7
 -> 8		printf("This is my program\n");			Indicates the line where it stopped
    9		bazz(i);
    10		return 0;
    11	}
 (lldb) thread step-over			Go to next line
 This is my program						Program prints out
 Process 9992 stopped
 * thread #1, name = 'temp', stop reason = step over
     frame #0: 0x0000000000201300 temp`main at temp.c:9:7
    6		int i;
    7
    8		printf("This is my program\n");
 -> 9		bazz(i);
    10		return 0;
    11	}
    12
 (lldb) thread step-in			step into bazz()
 Process 9992 stopped
 * thread #1, name = 'temp', stop reason = step in
     frame #0: 0x000000000020132b temp`bazz(anint=-5360) at temp.c:14:29	lldb displays stack frame
    11	}
    12
    13	int bazz(int anint) {
 -> 14		printf("You gave me %d\n", anint);
    15		return anint;
    16	}
 (lldb)
 ....
 
 Hang on a minute! How did anint get to be `-5360`? Was it not set to `5` in `main()`? Let us move up to `main()` and have a look.
 
 [source,bash]
 ....
 (lldb) up		Move up call stack
 frame #1: 0x000000000020130b temp`main at temp.c:9:2		lldb displays stack frame
    6		int i;
    7
    8		printf("This is my program\n");
 -> 9		bazz(i);
    10		return 0;
    11	}
    12
 (lldb) frame variable i			Show us the value of i
 (int) i = -5360							lldb displays -5360
 ....
 
 Oh dear! Looking at the code, we forgot to initialize i.
 We meant to put
 
 [.programlisting]
 ....
 ...
 main() {
 	int i;
 
 	i = 5;
 	printf("This is my program\n");
 ...
 ....
 
 but we left the `i=5;` line out.
 As we did not initialize i, it had whatever number happened to be in that area of memory when the program ran,
 which in this case happened to be `-5360`.
 
 [NOTE]
 ====
 The `lldb` command displays the stack frame every time we go into or out of a function, even if we are using `up` and `down` to move around the call stack.
 This shows the name of the function and the values of its arguments, which helps us keep track of where we are and what is going on.
 (The stack is a storage area where the program stores information about the arguments passed to functions and where to go when it returns from a function call.)
 ====
 
 ==== Examining a Core File with lldb
 
 A core file is basically a file which contains the complete state of the process when it crashed.
 In "the good old days", programmers had to print out hex listings of core files and sweat over machine code manuals, but now life is a bit easier.
 Incidentally, under FreeBSD and other 4.4BSD systems, a core file is called [.filename]#progname.core# instead of just [.filename]#core#, to make it clearer which program a core file belongs to.
 
 To examine a core file, specify the name of the core file in addition to the program itself.
 Instead of starting up `lldb` in the usual way, type `lldb -c _progname_.core -- _progname_`
 
 The debugger will display something like this:
 
 [source,bash,subs="verbatim,quotes"]
 ....
 % lldb -c [.filename]#progname.core# -- [.filename]#progname#
 (lldb) target create "[.filename]#progname#" --core "[.filename]#progname#.core"
 Core file '/home/pauamma/tmp/[.filename]#progname.core#' (x86_64) was loaded.
 (lldb)
 ....
 
 In this case, the program was called [.filename]#progname#, so the core file is called [.filename]#progname.core#.
 The debugger does not display why the program crashed or where.
 For this, use `thread backtrace all`.
 This will also show how the function where the program dumped core was called.
 
 [source,bash,subs="verbatim,quotes"]
 ....
 (lldb) thread backtrace all
 * thread #1, name = 'progname', stop reason = signal SIGSEGV
   * frame #0: 0x0000000000201347 progname`bazz(anint=5) at temp2.c:17:10
     frame #1: 0x0000000000201312 progname`main at temp2.c:10:2
     frame #2: 0x000000000020110f progname`_start(ap=<unavailable>, cleanup=<unavailable>) at crt1.c:76:7
 (lldb)
 ....
 
 `SIGSEGV` indicates that the program tried to access memory (run code or read/write data usually) at a location that does not belong to it, but does not give any specifics.
 For that, look at the source code at line 10 of file temp2.c, in `bazz()`.
 The backtrace also says that in this case, `bazz()` was called from `main()`.
 
 ==== Attaching to a Running Program with lldb
 
 One of the neatest features about `lldb` is that it can attach to a program that is already running.
 Of course, that requires sufficient permissions to do so.
 A common problem is stepping through a program that forks and wanting to trace the child, but the debugger will only trace the parent.
 
 To do that, start up another `lldb`, use `ps` to find the process ID for the child, and do
 
 [source,bash]
 ....
 (lldb) process attach -p pid
 ....
 
 in `lldb`, and then debug as usual.
 
 For that to work well, the code that calls `fork` to create the child needs to do something like the following (courtesy of the `gdb` info pages):
 
 [.programlisting]
 ....
 ...
 if ((pid = fork()) < 0)		/* _Always_ check this */
 	error();
 else if (pid == 0) {		/* child */
 	int PauseMode = 1;
 
 	while (PauseMode)
 		sleep(10);	/* Wait until someone attaches to us */
 	...
 } else {			/* parent */
 	...
 ....
 
 Now all that is needed is to attach to the child, set PauseMode to `0` with `expr PauseMode = 0` and wait for the `sleep()` call to return.
 
 === Remote Debugging Using LLDB
 
 [NOTE]
 ====
 The described functionality is available starting with LLDB version 12.0.0.
 Users of FreeBSD releases containing an earlier LLDB version may wish to use the snapshot available in link:{handbook}#ports-using/[ports or packages], as package:devel/llvm-devel[].
 ====
 
 Starting with LLDB 12.0.0, remote debugging is supported on FreeBSD.
 This means that `lldb-server` can be started to debug a program on one host, while the interactive `lldb` client connects to it from another one.
 
 To launch a new process to be debugged remotely, run `lldb-server` on the remote server by typing
 
 [source,bash]
 ....
 % lldb-server g host:port -- progname
 ....
 
 The process will be stopped immediately after launching, and `lldb-server` will wait for the client to connect.
 
 Start `lldb` locally and type the following command to connect to the remote server:
 
 [source,bash]
 ....
 (lldb) gdb-remote host:port
 ....
 
 `lldb-server` can also attach to a running process.
 To do that, type the following on the remote server:
 
 [source,bash]
 ....
 % lldb-server g host:port --attach pid-or-name
 ....
 
 === Using gdb
 
 ==== Starting gdb
 
 Start up gdb by typing
 
 [source,bash]
 ....
 % gdb progname
 ....
 
 although many people prefer to run it inside Emacs.
 To do this, type:
 
 [source,bash]
 ....
  M-x gdb RET progname RET
 ....
 
 Finally, for those finding its text-based command-prompt style off-putting, there is a graphical front-end for it (package:devel/xxgdb[]) in the Ports Collection.
 
 ==== Running a Program with gdb
 
 Compile the program with `-g` to get the most out of using `gdb`.
 It will work without, but will only display the name of the function currently running, instead of the source code.
 A line like:
 
 [source,bash]
 ....
 ... (no debugging symbols found) ...
 ....
 
 when `gdb` starts up means that the program was not compiled with `-g`.
 
 At the `gdb` prompt, type `break main`.
 This will tell the debugger to skip the preliminary set-up code in the program being run and to stop execution at the beginning of the program's code.
 Now type `run` to start the program- it will start at the beginning of the set-up code and then get stopped by the debugger when it calls `main()`.
 
 To step through the program a line at a time, press `n`.
 When at a function call, step into it by pressing `s`.
 Once in a function call, return from it by pressing `f`, or use `up` and `down` to take a quick look at the caller.
 
 Here is a simple example of how to spot a mistake in a program with `gdb`.
 This is our program (with a deliberate mistake):
 
 [.programlisting]
 ....
 #include <stdio.h>
 
 int bazz(int anint);
 
 main() {
 	int i;
 
 	printf("This is my program\n");
 	bazz(i);
 	return 0;
 }
 
 int bazz(int anint) {
 	printf("You gave me %d\n", anint);
 	return anint;
 }
 ....
 
 This program sets i to be `5` and passes it to a function `bazz()` which prints out the number we gave it.
 
 Compiling and running the program displays
 
 [source,bash]
 ....
 % cc -g -o temp temp.c
 % ./temp
 This is my program
 anint = 4231
 ....
 
 That was not what we expected! Time to see what is going on!
 
 [source,bash]
 ....
 % gdb temp
 GDB is free software and you are welcome to distribute copies of it
  under certain conditions; type "show copying" to see the conditions.
 There is absolutely no warranty for GDB; type "show warranty" for details.
 GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
 (gdb) break main				Skip the set-up code
 Breakpoint 1 at 0x160f: file temp.c, line 9.	gdb puts breakpoint at main()
 (gdb) run					Run as far as main()
 Starting program: /home/james/tmp/temp		Program starts running
 
 Breakpoint 1, main () at temp.c:9		gdb stops at main()
 (gdb) n						Go to next line
 This is my program				Program prints out
 (gdb) s						step into bazz()
 bazz (anint=4231) at temp.c:17			gdb displays stack frame
 (gdb)
 ....
 
 Hang on a minute! How did anint get to be `4231`? Was it not set to `5` in `main()`? Let us move up to `main()` and have a look.
 
 [source,bash]
 ....
 (gdb) up					Move up call stack
 #1  0x1625 in main () at temp.c:11		gdb displays stack frame
 (gdb) p i					Show us the value of i
 $1 = 4231					gdb displays 4231
 ....
 
 Oh dear! Looking at the code, we forgot to initialize i.
 We meant to put
 
 [.programlisting]
 ....
 ...
 main() {
 	int i;
 
 	i = 5;
 	printf("This is my program\n");
 ...
 ....
 
 but we left the `i=5;` line out.
 As we did not initialize i, it had whatever number happened to be in that area of memory when the program ran,
 which in this case happened to be `4231`.
 
 [NOTE]
 ====
 The `gdb` command displays the stack frame every time we go into or out of a function, even if we are using `up` and `down` to move around the call stack.
 This shows the name of the function and the values of its arguments, which helps us keep track of where we are and what is going on.
 (The stack is a storage area where the program stores information about the arguments passed to functions and where to go when it returns from a function call.)
 ====
 
 ==== Examining a Core File with gdb
 
 A core file is basically a file which contains the complete state of the process when it crashed.
 In "the good old days", programmers had to print out hex listings of core files and sweat over machine code manuals, but now life is a bit easier.
 Incidentally, under FreeBSD and other 4.4BSD systems, a core file is called [.filename]#progname.core# instead of just [.filename]#core#, to make it clearer which program a core file belongs to.
 
 To examine a core file, start up `gdb` in the usual way.
 Instead of typing `break` or `run`, type
 
 [source,bash]
 ....
 (gdb) core progname.core
 ....
 
 If the core file is not in the current directory, type `dir /path/to/core/file` first.
 
 The debugger should display something like this:
 
 [source,bash,subs="verbatim,quotes"]
 ....
 % gdb [.filename]#progname#
 GDB is free software and you are welcome to distribute copies of it
  under certain conditions; type "show copying" to see the conditions.
 There is absolutely no warranty for GDB; type "show warranty" for details.
 GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
 (gdb) core [.filename]#progname.core#
 Core was generated by `[.filename]#progname#'.
 Program terminated with signal 11, Segmentation fault.
 Cannot access memory at address 0x7020796d.
 #0  0x164a in bazz (anint=0x5) at temp.c:17
 (gdb)
 ....
 
 In this case, the program was called [.filename]#progname#, so the core file is called [.filename]#progname.core#.
 We can see that the program crashed due to trying to access an area in memory that was not available to it in a function called `bazz`.
 
 Sometimes it is useful to be able to see how a function was called,
 as the problem could have occurred a long way up the call stack in a complex program.
 `bt` causes `gdb` to print out a back-trace of the call stack:
 
 [source,bash]
 ....
 (gdb) bt
 #0  0x164a in bazz (anint=0x5) at temp.c:17
 #1  0xefbfd888 in end ()
 #2  0x162c in main () at temp.c:11
 (gdb)
 ....
 
 The `end()` function is called when a program crashes;
 in this case, the `bazz()` function was called from `main()`.
 
 ==== Attaching to a Running Program with gdb
 
 One of the neatest features about `gdb` is that it can attach to a program that is already running.
 Of course, that requires sufficient permissions to do so.
 A common problem is stepping through a program that forks and wanting to trace the child, but the debugger will only trace the parent.
 
 To do that, start up another `gdb`, use `ps` to find the process ID for the child, and do
 
 [source,bash]
 ....
 (gdb) attach pid
 ....
 
 in `gdb`, and then debug as usual.
 
 For that to work well, the code that calls `fork` to create the child needs to do something like the following (courtesy of the `gdb` info pages):
 
 [.programlisting]
 ....
 ...
 if ((pid = fork()) < 0)		/* _Always_ check this */
 	error();
 else if (pid == 0) {		/* child */
 	int PauseMode = 1;
 
 	while (PauseMode)
 		sleep(10);	/* Wait until someone attaches to us */
 	...
 } else {			/* parent */
 	...
 ....
 
 Now all that is needed is to attach to the child, set PauseMode to `0`, and wait for the `sleep()` call to return!
 
 [[emacs]]
 == Using Emacs as a Development Environment
 
 === Emacs
 
 Emacs is a highly customizable editor-indeed, it has been customized to the point where it is more like an operating system than an editor!
 Many developers and sysadmins do in fact spend practically all their time working inside Emacs, leaving it only to log out.
 
 It is impossible even to summarize everything Emacs can do here, but here are some of the features of interest to developers:
 
 * Very powerful editor, allowing search-and-replace on both strings and regular expressions (patterns), jumping to start/end of block expression, etc, etc.
 * Pull-down menus and online help.
 * Language-dependent syntax highlighting and indentation.
 * Completely customizable.
 * You can compile and debug programs within Emacs.
 * On a compilation error, you can jump to the offending line of source code.
 * Friendly-ish front-end to the `info` program used for reading GNU hypertext documentation, including the documentation on Emacs itself.
 * Friendly front-end to `gdb`, allowing you to look at the source code as you step through your program.
 
 And doubtless many more that have been overlooked.
 
 Emacs can be installed on FreeBSD using the package:editors/emacs[] port.
 
 Once it is installed, start it up and do `C-h t` to read an Emacs tutorial-that means hold down kbd:[control], press kbd:[h], let go of kbd:[control], and then press kbd:[t].
 (Alternatively, you can use the mouse to select [.guimenuitem]#Emacs Tutorial# from the menu:Help[] menu.)
 
 Although Emacs does have menus, it is well worth learning the key bindings,
 as it is much quicker when you are editing something to press a couple of keys than to try to find the mouse and then click on the right place.
 And, when you are talking to seasoned Emacs users, you will find they often casually throw around expressions like "`M-x replace-s RET foo RET bar RET`" so it is useful to know what they mean.
 And in any case, Emacs has far too many useful functions for them to all fit on the menu bars.
 
 Fortunately, it is quite easy to pick up the key-bindings, as they are displayed next to the menu item.
 My advice is to use the menu item for, say, opening a file until you understand how it works and feel confident with it, then try doing C-x C-f.
 When you are happy with that, move on to another menu command.
 
 If you cannot remember what a particular combination of keys does, select [.guimenuitem]#Describe Key# from the menu:Help[] menu and type it in-Emacs will tell you what it does.
 You can also use the [.guimenuitem]#Command Apropos# menu item to find out all the commands which contain a particular word in them, with the key binding next to it.
 
 By the way, the expression above means hold down the kbd:[Meta] key, press kbd:[x], release the kbd:[Meta] key, type `replace-s` (short for `replace-string`-another feature of Emacs is that you can abbreviate commands), press the kbd:[return] key, type `foo` (the string you want replaced), press the kbd:[return] key, type bar (the string you want to replace `foo` with) and press kbd:[return] again.
 Emacs will then do the search-and-replace operation you have just requested.
 
 If you are wondering what on earth kbd:[Meta] is, it is a special key that many UNIX(R) workstations have.
 Unfortunately, PC's do not have one, so it is usually kbd:[alt] (or if you are unlucky, the kbd:[escape] key).
 
 Oh, and to get out of Emacs, do `C-x C-c` (that means hold down the kbd:[control] key, press kbd:[x], press kbd:[c] and release the kbd:[control] key).
 If you have any unsaved files open, Emacs will ask you if you want to save them.
 (Ignore the bit in the documentation where it says `C-z` is the usual way to leave Emacs-that leaves Emacs hanging around in the background, and is only really useful if you are on a system which does not have virtual terminals).
 
 === Configuring Emacs
 
 Emacs does many wonderful things; some of them are built in, some of them need to be configured.
 
 Instead of using a proprietary macro language for configuration, Emacs uses a version of Lisp specially adapted for editors, known as Emacs Lisp.
 Working with Emacs Lisp can be quite helpful if you want to go on and learn something like Common Lisp.
 Emacs Lisp has many features of Common Lisp, although it is considerably smaller (and thus easier to master).
 
 The best way to learn Emacs Lisp is to download the link:ftp://ftp.gnu.org/old-gnu/emacs/elisp-manual-19-2.4.tar.gz[Emacs Tutorial]
 
 However, there is no need to actually know any Lisp to get started with configuring Emacs,
 as I have included a sample [.filename]#.emacs#, which should be enough to get you started.
 Just copy it into your home directory and restart Emacs if it is already running;
 it will read the commands from the file and (hopefully) give you a useful basic setup.
 
 === A Sample [.filename]#.emacs#
 
 Unfortunately, there is far too much here to explain it in detail; however there are one or two points worth mentioning.
 
 * Everything beginning with a `;` is a comment and is ignored by Emacs.
 * In the first line, the `-*- Emacs-Lisp -*-` is so that we can edit [.filename]#.emacs# itself within Emacs and get all the fancy features for editing Emacs Lisp. Emacs usually tries to guess this based on the filename, and may not get it right for [.filename]#.emacs#.
 * The kbd:[tab] key is bound to an indentation function in some modes, so when you press the tab key, it will indent the current line of code. If you want to put a tab character in whatever you are writing, hold the kbd:[control] key down while you are pressing the kbd:[tab] key.
 * This file supports syntax highlighting for C, C++, Perl, Lisp and Scheme, by guessing the language from the filename.
 * Emacs already has a pre-defined function called `next-error`. In a compilation output window, this allows you to move from one compilation error to the next by doing `M-n`; we define a complementary function, `previous-error`, that allows you to go to a previous error by doing `M-p`. The nicest feature of all is that `C-c C-c` will open up the source file in which the error occurred and jump to the appropriate line.
 * We enable Emacs's ability to act as a server, so that if you are doing something outside Emacs and you want to edit a file, you can just type in
 +
 [source,bash]
 ....
 % emacsclient filename
 ....
-+ 
++
 and then you can edit the file in your Emacs!footnote:[Many Emacs users set their EDITOR environment to emacsclient so this happens every time they need to edit a file.]
 
 .A Sample [.filename]#.emacs#
 ====
 [.programlisting]
 ....
 ;; -*-Emacs-Lisp-*-
 
 ;; This file is designed to be re-evaled; use the variable first-time
 ;; to avoid any problems with this.
 (defvar first-time t
   "Flag signifying this is the first time that .emacs has been evaled")
 
 ;; Meta
 (global-set-key "\M- " 'set-mark-command)
 (global-set-key "\M-\C-h" 'backward-kill-word)
 (global-set-key "\M-\C-r" 'query-replace)
 (global-set-key "\M-r" 'replace-string)
 (global-set-key "\M-g" 'goto-line)
 (global-set-key "\M-h" 'help-command)
 
 ;; Function keys
 (global-set-key [f1] 'manual-entry)
 (global-set-key [f2] 'info)
 (global-set-key [f3] 'repeat-complex-command)
 (global-set-key [f4] 'advertised-undo)
 (global-set-key [f5] 'eval-current-buffer)
 (global-set-key [f6] 'buffer-menu)
 (global-set-key [f7] 'other-window)
 (global-set-key [f8] 'find-file)
 (global-set-key [f9] 'save-buffer)
 (global-set-key [f10] 'next-error)
 (global-set-key [f11] 'compile)
 (global-set-key [f12] 'grep)
 (global-set-key [C-f1] 'compile)
 (global-set-key [C-f2] 'grep)
 (global-set-key [C-f3] 'next-error)
 (global-set-key [C-f4] 'previous-error)
 (global-set-key [C-f5] 'display-faces)
 (global-set-key [C-f8] 'dired)
 (global-set-key [C-f10] 'kill-compilation)
 
 ;; Keypad bindings
 (global-set-key [up] "\C-p")
 (global-set-key [down] "\C-n")
 (global-set-key [left] "\C-b")
 (global-set-key [right] "\C-f")
 (global-set-key [home] "\C-a")
 (global-set-key [end] "\C-e")
 (global-set-key [prior] "\M-v")
 (global-set-key [next] "\C-v")
 (global-set-key [C-up] "\M-\C-b")
 (global-set-key [C-down] "\M-\C-f")
 (global-set-key [C-left] "\M-b")
 (global-set-key [C-right] "\M-f")
 (global-set-key [C-home] "\M-<")
 (global-set-key [C-end] "\M->")
 (global-set-key [C-prior] "\M-<")
 (global-set-key [C-next] "\M->")
 
 ;; Mouse
 (global-set-key [mouse-3] 'imenu)
 
 ;; Misc
 (global-set-key [C-tab] "\C-q\t")	; Control tab quotes a tab.
 (setq backup-by-copying-when-mismatch t)
 
 ;; Treat 'y' or <CR> as yes, 'n' as no.
 (fset 'yes-or-no-p 'y-or-n-p)
 (define-key query-replace-map [return] 'act)
 (define-key query-replace-map [?\C-m] 'act)
 
 ;; Load packages
 (require 'desktop)
 (require 'tar-mode)
 
 ;; Pretty diff mode
 (autoload 'ediff-buffers "ediff" "Intelligent Emacs interface to diff" t)
 (autoload 'ediff-files "ediff" "Intelligent Emacs interface to diff" t)
 (autoload 'ediff-files-remote "ediff"
   "Intelligent Emacs interface to diff")
 
 (if first-time
     (setq auto-mode-alist
 	  (append '(("\\.cpp$" . c++-mode)
 		    ("\\.hpp$" . c++-mode)
 		    ("\\.lsp$" . lisp-mode)
 		    ("\\.scm$" . scheme-mode)
 		    ("\\.pl$" . perl-mode)
 		    ) auto-mode-alist)))
 
 ;; Auto font lock mode
 (defvar font-lock-auto-mode-list
   (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'lisp-mode 'perl-mode 'scheme-mode)
   "List of modes to always start in font-lock-mode")
 
 (defvar font-lock-mode-keyword-alist
   '((c++-c-mode . c-font-lock-keywords)
     (perl-mode . perl-font-lock-keywords))
   "Associations between modes and keywords")
 
 (defun font-lock-auto-mode-select ()
   "Automatically select font-lock-mode if the current major mode is in font-lock-auto-mode-list"
   (if (memq major-mode font-lock-auto-mode-list)
       (progn
 	(font-lock-mode t))
     )
   )
 
 (global-set-key [M-f1] 'font-lock-fontify-buffer)
 
 ;; New dabbrev stuff
 ;(require 'new-dabbrev)
 (setq dabbrev-always-check-other-buffers t)
 (setq dabbrev-abbrev-char-regexp "\\sw\\|\\s_")
 (add-hook 'emacs-lisp-mode-hook
 	  '(lambda ()
 	     (set (make-local-variable 'dabbrev-case-fold-search) nil)
 	     (set (make-local-variable 'dabbrev-case-replace) nil)))
 (add-hook 'c-mode-hook
 	  '(lambda ()
 	     (set (make-local-variable 'dabbrev-case-fold-search) nil)
 	     (set (make-local-variable 'dabbrev-case-replace) nil)))
 (add-hook 'text-mode-hook
 	  '(lambda ()
 	     (set (make-local-variable 'dabbrev-case-fold-search) t)
 	     (set (make-local-variable 'dabbrev-case-replace) t)))
 
 ;; C++ and C mode...
 (defun my-c++-mode-hook ()
   (setq tab-width 4)
   (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
   (define-key c++-mode-map "\C-ce" 'c-comment-edit)
   (setq c++-auto-hungry-initial-state 'none)
   (setq c++-delete-function 'backward-delete-char)
   (setq c++-tab-always-indent t)
   (setq c-indent-level 4)
   (setq c-continued-statement-offset 4)
   (setq c++-empty-arglist-indent 4))
 
 (defun my-c-mode-hook ()
   (setq tab-width 4)
   (define-key c-mode-map "\C-m" 'reindent-then-newline-and-indent)
   (define-key c-mode-map "\C-ce" 'c-comment-edit)
   (setq c-auto-hungry-initial-state 'none)
   (setq c-delete-function 'backward-delete-char)
   (setq c-tab-always-indent t)
 ;; BSD-ish indentation style
   (setq c-indent-level 4)
   (setq c-continued-statement-offset 4)
   (setq c-brace-offset -4)
   (setq c-argdecl-indent 0)
   (setq c-label-offset -4))
 
 ;; Perl mode
 (defun my-perl-mode-hook ()
   (setq tab-width 4)
   (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
   (setq perl-indent-level 4)
   (setq perl-continued-statement-offset 4))
 
 ;; Scheme mode...
 (defun my-scheme-mode-hook ()
   (define-key scheme-mode-map "\C-m" 'reindent-then-newline-and-indent))
 
 ;; Emacs-Lisp mode...
 (defun my-lisp-mode-hook ()
   (define-key lisp-mode-map "\C-m" 'reindent-then-newline-and-indent)
   (define-key lisp-mode-map "\C-i" 'lisp-indent-line)
   (define-key lisp-mode-map "\C-j" 'eval-print-last-sexp))
 
 ;; Add all of the hooks...
 (add-hook 'c++-mode-hook 'my-c++-mode-hook)
 (add-hook 'c-mode-hook 'my-c-mode-hook)
 (add-hook 'scheme-mode-hook 'my-scheme-mode-hook)
 (add-hook 'emacs-lisp-mode-hook 'my-lisp-mode-hook)
 (add-hook 'lisp-mode-hook 'my-lisp-mode-hook)
 (add-hook 'perl-mode-hook 'my-perl-mode-hook)
 
 ;; Complement to next-error
 (defun previous-error (n)
   "Visit previous compilation error message and corresponding source code."
   (interactive "p")
   (next-error (- n)))
 
 ;; Misc...
 (transient-mark-mode 1)
 (setq mark-even-if-inactive t)
 (setq visible-bell nil)
 (setq next-line-add-newlines nil)
 (setq compile-command "make")
 (setq suggest-key-bindings nil)
 (put 'eval-expression 'disabled nil)
 (put 'narrow-to-region 'disabled nil)
 (put 'set-goal-column 'disabled nil)
 (if (>= emacs-major-version 21)
 	(setq show-trailing-whitespace t))
 
 ;; Elisp archive searching
 (autoload 'format-lisp-code-directory "lispdir" nil t)
 (autoload 'lisp-dir-apropos "lispdir" nil t)
 (autoload 'lisp-dir-retrieve "lispdir" nil t)
 (autoload 'lisp-dir-verify "lispdir" nil t)
 
 ;; Font lock mode
 (defun my-make-face (face color &optional bold)
   "Create a face from a color and optionally make it bold"
   (make-face face)
   (copy-face 'default face)
   (set-face-foreground face color)
   (if bold (make-face-bold face))
   )
 
 (if (eq window-system 'x)
     (progn
       (my-make-face 'blue "blue")
       (my-make-face 'red "red")
       (my-make-face 'green "dark green")
       (setq font-lock-comment-face 'blue)
       (setq font-lock-string-face 'bold)
       (setq font-lock-type-face 'bold)
       (setq font-lock-keyword-face 'bold)
       (setq font-lock-function-name-face 'red)
       (setq font-lock-doc-string-face 'green)
       (add-hook 'find-file-hooks 'font-lock-auto-mode-select)
 
       (setq baud-rate 1000000)
       (global-set-key "\C-cmm" 'menu-bar-mode)
       (global-set-key "\C-cms" 'scroll-bar-mode)
       (global-set-key [backspace] 'backward-delete-char)
 					;      (global-set-key [delete] 'delete-char)
       (standard-display-european t)
       (load-library "iso-transl")))
 
 ;; X11 or PC using direct screen writes
 (if window-system
     (progn
       ;;      (global-set-key [M-f1] 'hilit-repaint-command)
       ;;      (global-set-key [M-f2] [?\C-u M-f1])
       (setq hilit-mode-enable-list
 	    '(not text-mode c-mode c++-mode emacs-lisp-mode lisp-mode
 		  scheme-mode)
 	    hilit-auto-highlight nil
 	    hilit-auto-rehighlight 'visible
 	    hilit-inhibit-hooks nil
 	    hilit-inhibit-rebinding t)
       (require 'hilit19)
       (require 'paren))
   (setq baud-rate 2400)			; For slow serial connections
   )
 
 ;; TTY type terminal
 (if (and (not window-system)
 	 (not (equal system-type 'ms-dos)))
     (progn
       (if first-time
 	  (progn
 	    (keyboard-translate ?\C-h ?\C-?)
 	    (keyboard-translate ?\C-? ?\C-h)))))
 
 ;; Under UNIX
 (if (not (equal system-type 'ms-dos))
     (progn
       (if first-time
 	  (server-start))))
 
 ;; Add any face changes here
 (add-hook 'term-setup-hook 'my-term-setup-hook)
 (defun my-term-setup-hook ()
   (if (eq window-system 'pc)
       (progn
 ;;	(set-face-background 'default "red")
 	)))
 
 ;; Restore the "desktop" - do this as late as possible
 (if first-time
     (progn
       (desktop-load-default)
       (desktop-read)))
 
 ;; Indicate that this file has been read at least once
 (setq first-time nil)
 
 ;; No need to debug anything now
 
 (setq debug-on-error nil)
 
 ;; All done
 (message "All done, %s%s" (user-login-name) ".")
 ....
 ====
 
 === Extending the Range of Languages Emacs Understands
 
 Now, this is all very well if you only want to program in the languages already catered for in [.filename]#.emacs# (C, C++, Perl, Lisp and Scheme), but what happens if a new language called "whizbang" comes out, full of exciting features?
 
 The first thing to do is find out if whizbang comes with any files that tell Emacs about the language.
 These usually end in [.filename]#.el#, short for "Emacs Lisp".
 For example, if whizbang is a FreeBSD port, we can locate these files by doing
 
 [source,bash]
 ....
 % find /usr/ports/lang/whizbang -name "*.el" -print
 ....
 
 and install them by copying them into the Emacs site Lisp directory.
 On FreeBSD, this is [.filename]#/usr/local/share/emacs/site-lisp#.
 
 So for example, if the output from the find command was
 
 [source,bash]
 ....
 /usr/ports/lang/whizbang/work/misc/whizbang.el
 ....
 
 we would do
 
 [source,bash]
 ....
 # cp /usr/ports/lang/whizbang/work/misc/whizbang.el /usr/local/share/emacs/site-lisp
 ....
 
 Next, we need to decide what extension whizbang source files have.
 Let us say for the sake of argument that they all end in [.filename]#.wiz#.
 We need to add an entry to our [.filename]#.emacs# to make sure Emacs will be able to use the information in [.filename]#whizbang.el#.
 
 Find the auto-mode-alist entry in [.filename]#.emacs# and add a line for whizbang, such as:
 
 [.programlisting]
 ....
 ...
 ("\\.lsp$" . lisp-mode)
 ("\\.wiz$" . whizbang-mode)
 ("\\.scm$" . scheme-mode)
 ...
 ....
 
 This means that Emacs will automatically go into `whizbang-mode` when you edit a file ending in [.filename]#.wiz#.
 
 Just below this, you will find the font-lock-auto-mode-list entry.
 Add `whizbang-mode` to it like so:
 
 [.programlisting]
 ....
 ;; Auto font lock mode
 (defvar font-lock-auto-mode-list
   (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'whizbang-mode 'lisp-mode 'perl-mode 'scheme-mode)
   "List of modes to always start in font-lock-mode")
 ....
 
 This means that Emacs will always enable `font-lock-mode` (ie syntax highlighting) when editing a [.filename]#.wiz# file.
 
 And that is all that is needed. If there is anything else you want done automatically when you open up [.filename]#.wiz#,
 you can add a `whizbang-mode hook` (see `my-scheme-mode-hook` for a simple example that adds `auto-indent`).
 
 [[tools-reading]]
 == Further Reading
 
 For information about setting up a development environment for contributing fixes to FreeBSD itself, please see man:development[7].
 
 * Brian Harvey and Matthew Wright _Simply Scheme_ MIT 1994. ISBN 0-262-08226-8
 * Randall Schwartz _Learning Perl_ O'Reilly 1993 ISBN 1-56592-042-2
 * Patrick Henry Winston and Berthold Klaus Paul Horn _Lisp (3rd Edition)_ Addison-Wesley 1989 ISBN 0-201-08319-1
 * Brian W. Kernighan and Rob Pike _The Unix Programming Environment_ Prentice-Hall 1984 ISBN 0-13-937681-X
 * Brian W. Kernighan and Dennis M. Ritchie _The C Programming Language (2nd Edition)_ Prentice-Hall 1988 ISBN 0-13-110362-8
 * Bjarne Stroustrup _The C++ Programming Language_ Addison-Wesley 1991 ISBN 0-201-53992-6
 * W. Richard Stevens _Advanced Programming in the Unix Environment_ Addison-Wesley 1992 ISBN 0-201-56317-7
 * W. Richard Stevens _Unix Network Programming_ Prentice-Hall 1990 ISBN 0-13-949876-1
diff --git a/documentation/content/en/books/developers-handbook/x86/_index.adoc b/documentation/content/en/books/developers-handbook/x86/_index.adoc
index 9d463b5e49..e8a5250edb 100644
--- a/documentation/content/en/books/developers-handbook/x86/_index.adoc
+++ b/documentation/content/en/books/developers-handbook/x86/_index.adoc
@@ -1,4297 +1,4297 @@
 ---
 title: Chapter 11. x86 Assembly Language Programming
 authors:
 prev: books/developers-handbook/partiv
 next: books/developers-handbook/partv
 description: x86 Assembly Language Programming
 tags: ["x86", "guide"]
 ---
 
 [[x86]]
 = x86 Assembly Language Programming
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 11
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 _This chapter was written by {stanislav}._
 
 [[x86-intro]]
 == Synopsis
 
 Assembly language programming under UNIX(R) is highly undocumented.
 It is generally assumed that no one would ever want to use it because various UNIX(R) systems run on different microprocessors, so everything should be written in C for portability.
 
 In reality, C portability is quite a myth.
 Even C programs need to be modified when ported from one UNIX(R) to another, regardless of what processor each runs on.
 Typically, such a program is full of conditional statements depending on the system it is compiled for.
 
 Even if we believe that all of UNIX(R) software should be written in C, or some other high-level language, we still need assembly language programmers: Who else would write the section of C library that accesses the kernel?
 
 In this chapter I will attempt to show you how you can use assembly language writing UNIX(R) programs, specifically under FreeBSD.
 
 This chapter does not explain the basics of assembly language.
 There are enough resources about that (for a complete online course in assembly language, see Randall Hyde's http://webster.cs.ucr.edu/[Art of Assembly Language];
 or if you prefer a printed book, take a look at Jeff Duntemann's Assembly Language Step-by-Step (ISBN: 0471375233).
 However, once the chapter is finished, any assembly language programmer will be able to write programs for FreeBSD quickly and efficiently.
 
 Copyright (R) 2000-2001 G. Adam Stanislav. All rights reserved.
 
 [[x86-the-tools]]
 == The Tools
 
 [[x86-the-assembler]]
 === The Assembler
 
 The most important tool for assembly language programming is the assembler, the software that converts assembly language code into machine language.
 
 Two very different assemblers are available for FreeBSD.
 One is  man:as[1], which uses the traditional UNIX(R) assembly language syntax.
 It comes with the system.
 
 The other is /usr/ports/devel/nasm.
 It uses the Intel syntax.
 Its main advantage is that it can assemble code for many operating systems.
 It needs to be installed separately, but is completely free.
 
 This chapter uses nasm syntax because most assembly language programmers coming to FreeBSD from other operating systems will find it easier to understand.
 And, because, quite frankly, that is what I am used to.
 
 [[x86-the-linker]]
 === The Linker
 
 The output of the assembler, like that of any compiler, needs to be linked to form an executable file.
 
 The standard  man:ld[1] linker comes with FreeBSD.
 It works with the code assembled with either assembler.
 
 [[x86-system-calls]]
 == System Calls
 
 [[x86-default-calling-convention]]
 === Default Calling Convention
 
 By default, the FreeBSD kernel uses the C calling convention.
 Further, although the kernel is accessed using `int 80h`, it is assumed the program will call a function that issues `int 80h`, rather than issuing `int 80h` directly.
 
 This convention is very convenient, and quite superior to the Microsoft(R) convention used by MS-DOS(R).
 Why? Because the UNIX(R) convention allows any program written in any language to access the kernel.
 
 An assembly language program can do that as well.
 For example, we could open a file:
 
 [.programlisting]
 ....
 kernel:
 	int	80h	; Call kernel
 	ret
 
 open:
 	push	dword mode
 	push	dword flags
 	push	dword path
 	mov	eax, 5
 	call	kernel
 	add	esp, byte 12
 	ret
 ....
 
 This is a very clean and portable way of coding.
 If you need to port the code to a UNIX(R) system which uses a different interrupt, or a different way of passing parameters, all you need to change is the kernel procedure.
 
 But assembly language programmers like to shave off cycles.
 The above example requires a `call/ret` combination.
 We can eliminate it by ``push``ing an extra dword:
 
 [.programlisting]
 ....
 open:
 	push	dword mode
 	push	dword flags
 	push	dword path
 	mov	eax, 5
 	push	eax		; Or any other dword
 	int	80h
 	add	esp, byte 16
 ....
 
 The `5` that we have placed in `EAX` identifies the kernel function, in this case `open`.
 
 [[x86-alternate-calling-convention]]
 === Alternate Calling Convention
 
 FreeBSD is an extremely flexible system.
 It offers other ways of calling the kernel.
 For it to work, however, the system must have Linux emulation installed.
 
 Linux is a UNIX(R) like system.
 However, its kernel uses the same system-call convention of passing parameters in registers MS-DOS(R) does.
 As with the UNIX(R) convention, the function number is placed in `EAX`.
 The parameters, however, are not passed on the stack but in `EBX, ECX, EDX, ESI, EDI, EBP`:
 
 [.programlisting]
 ....
 open:
 	mov	eax, 5
 	mov	ebx, path
 	mov	ecx, flags
 	mov	edx, mode
 	int	80h
 ....
 
 This convention has a great disadvantage over the UNIX(R) way, at least as far as assembly language programming is concerned: 
 Every time you make a kernel call you must `push` the registers, then `pop` them later.
 This makes your code bulkier and slower.
 Nevertheless, FreeBSD gives you a choice.
 
 If you do choose the Linux convention, you must let the system know about it.
 After your program is assembled and linked, you need to brand the executable:
 
 [source,shell]
 ....
 % brandelf -t Linux filename
 ....
 
 [[x86-use-geneva]]
 === Which Convention Should You Use?
 
 If you are coding specifically for FreeBSD, you should always use the UNIX(R) convention:
 It is faster, you can store global variables in registers, you do not have to brand the executable,
 and you do not impose the installation of the Linux emulation package on the target system.
 
 If you want to create portable code that can also run on Linux, you will probably still want to give the FreeBSD users as efficient a code as possible.
 I will show you how you can accomplish that after I have explained the basics.
 
 [[x86-call-numbers]]
 === Call Numbers
 
 To tell the kernel which system service you are calling, place its number in `EAX`.
 Of course, you need to know what the number is.
 
 [[x86-the-syscalls-file]]
 ==== The [.filename]#syscalls# File
 
 The numbers are listed in [.filename]#syscalls#.
 `locate syscalls` finds this file in several different formats, all produced automatically from [.filename]#syscalls.master#.
 
 You can find the master file for the default UNIX(R) calling convention in [.filename]#/usr/src/sys/kern/syscalls.master#.
 If you need to use the other convention implemented in the Linux emulation mode, read [.filename]#/usr/src/sys/i386/linux/syscalls.master#.
 
 [NOTE]
 ====
 Not only do FreeBSD and Linux use different calling conventions, they sometimes use different numbers for the same functions.
 ====
 
 [.filename]#syscalls.master# describes how the call is to be made:
 
 [.programlisting]
 ....
 0	STD	NOHIDE	{ int nosys(void); } syscall nosys_args int
 1	STD	NOHIDE	{ void exit(int rval); } exit rexit_args void
 2	STD	POSIX	{ int fork(void); }
 3	STD	POSIX	{ ssize_t read(int fd, void *buf, size_t nbyte); }
 4	STD	POSIX	{ ssize_t write(int fd, const void *buf, size_t nbyte); }
 5	STD	POSIX	{ int open(char *path, int flags, int mode); }
 6	STD	POSIX	{ int close(int fd); }
 etc...
 ....
 
 It is the leftmost column that tells us the number to place in `EAX`.
 
 The rightmost column tells us what parameters to `push`.
 They are ``push``ed _from right to left_.
 
 For example, to `open` a file, we need to `push` the `mode` first, then `flags`, then the address at which the `path` is stored.
 
 [[x86-return-values]]
 == Return Values
 
 A system call would not be useful most of the time if it did not return some kind of a value:
 The file descriptor of an open file, the number of bytes read to a buffer, the system time, etc.
 
 Additionally, the system needs to inform us if an error occurs:
 A file does not exist, system resources are exhausted, we passed an invalid parameter, etc.
 
 [[x86-man-pages]]
 === Man Pages
 
 The traditional place to look for information about various system calls under UNIX(R) systems are the manual pages.
 FreeBSD describes its system calls in section 2, sometimes in section 3.
 
 For example,  man:open[2] says:
 
 [.blockquote]
 If successful, `open()` returns a non-negative integer, termed a file descriptor.
 It returns `-1` on failure, and sets `errno` to indicate the error.
 
 The assembly language programmer new to UNIX(R) and FreeBSD will immediately ask the puzzling question: Where is `errno` and how do I get to it?
 
 [NOTE]
 ====
 The information presented in the manual pages applies to C programs.
 The assembly language programmer needs additional information.
 ====
 
 [[x86-where-return-values]]
 === Where Are the Return Values?
 
 Unfortunately, it depends... For most system calls it is in `EAX`, but not for all.
 A good rule of thumb, when working with a system call for the first time, is to look for the return value in `EAX`.
 If it is not there, you need further research.
 
 [NOTE]
 ====
 I am aware of one system call that returns the value in `EDX`: `SYS_fork`.
 All others I have worked with use `EAX`.
 But I have not worked with them all yet.
 ====
 
 [TIP]
 ====
 If you cannot find the answer here or anywhere else, study libc source code and see how it interfaces with the kernel.
 ====
 
 [[x86-where-errno]]
 === Where Is `errno`?
 
 Actually, nowhere...
 
 `errno` is part of the C language, not the UNIX(R) kernel.
 When accessing kernel services directly, the error code is returned in `EAX`, the same register the proper return value generally ends up in.
 
 This makes perfect sense. If there is no error, there is no error code.
 If there is an error, there is no return value.
 One register can contain either.
 
 [[x86-how-to-know-error]]
 === Determining an Error Occurred
 
 When using the standard FreeBSD calling convention, the `carry flag` is cleared upon success, set upon failure.
 
 When using the Linux emulation mode, the signed value in `EAX` is non-negative upon success, and contains the return value.
 In case of an error, the value is negative, i.e., `-errno`.
 
 [[x86-portable-code]]
 == Creating Portable Code
 
 Portability is generally not one of the strengths of assembly language.
 Yet, writing assembly language programs for different platforms is possible, especially with nasm.
 I have written assembly language libraries that can be assembled for such different operating systems as Windows(R) and FreeBSD.
 
 It is all the more possible when you want your code to run on two platforms which, while different, are based on similar architectures.
 
 For example, FreeBSD is UNIX(R), Linux is UNIX(R) like.
 I only mentioned three differences between them (from an assembly language programmer's perspective):
 The calling convention, the function numbers, and the way of returning values.
 
 [[x86-deal-with-function-numbers]]
 === Dealing with Function Numbers
 
 In many cases the function numbers are the same.
 However, even when they are not, the problem is easy to deal with:
 Instead of using numbers in your code, use constants which you have declared differently depending on the target architecture:
 
 [.programlisting]
 ....
 %ifdef	LINUX
 %define	SYS_execve	11
 %else
 %define	SYS_execve	59
 %endif
 ....
 
 [[x86-deal-with-geneva]]
 === Dealing with Conventions
 
 Both, the calling convention, and the return value (the `errno` problem) can be resolved with macros:
 
 [.programlisting]
 ....
 %ifdef	LINUX
 
 %macro	system	0
 	call	kernel
 %endmacro
 
 align 4
 kernel:
 	push	ebx
 	push	ecx
 	push	edx
 	push	esi
 	push	edi
 	push	ebp
 
 	mov	ebx, [esp+32]
 	mov	ecx, [esp+36]
 	mov	edx, [esp+40]
 	mov	esi, [esp+44]
 	mov	ebp, [esp+48]
 	int	80h
 
 	pop	ebp
 	pop	edi
 	pop	esi
 	pop	edx
 	pop	ecx
 	pop	ebx
 
 	or	eax, eax
 	js	.errno
 	clc
 	ret
 
 .errno:
 	neg	eax
 	stc
 	ret
 
 %else
 
 %macro	system	0
 	int	80h
 %endmacro
 
 %endif
 ....
 
 [[x86-deal-with-other-portability]]
 === Dealing with Other Portability Issues
 
 The above solutions can handle most cases of writing code portable between FreeBSD and Linux.
 Nevertheless, with some kernel services the differences are deeper.
 
 In that case, you need to write two different handlers for those particular system calls, and use conditional assembly.
 Luckily, most of your code does something other than calling the kernel, so usually you will only need a few such conditional sections in your code.
 
 [[x86-portable-library]]
 === Using a Library
 
 You can avoid portability issues in your main code altogether by writing a library of system calls.
 Create a separate library for FreeBSD, a different one for Linux, and yet other libraries for more operating systems.
 
 In your library, write a separate function (or procedure, if you prefer the traditional assembly language terminology) for each system call.
 Use the C calling convention of passing parameters.
 But still use `EAX` to pass the call number in.
 In that case, your FreeBSD library can be very simple, as many seemingly different functions can be just labels to the same code:
 
 [.programlisting]
 ....
 sys.open:
 sys.close:
 [etc...]
 	int	80h
 	ret
 ....
 
 Your Linux library will require more different functions.
 But even here you can group system calls using the same number of parameters:
 
 [.programlisting]
 ....
 sys.exit:
 sys.close:
 [etc... one-parameter functions]
 	push	ebx
 	mov	ebx, [esp+12]
 	int	80h
 	pop	ebx
 	jmp	sys.return
 
 ...
 
 sys.return:
 	or	eax, eax
 	js	sys.err
 	clc
 	ret
 
 sys.err:
 	neg	eax
 	stc
 	ret
 ....
 
 The library approach may seem inconvenient at first because it requires you to produce a separate file your code depends on.
 But it has many advantages: For one, you only need to write it once and can use it for all your programs.
 You can even let other assembly language programmers use it, or perhaps use one written by someone else.
 But perhaps the greatest advantage of the library is that your code can be ported to other systems,
 even by other programmers, by simply writing a new library without any changes to your code.
 
 If you do not like the idea of having a library, you can at least place all your system calls in a separate assembly language file and link it with your main program. Here, again, all porters have to do is create a new object file to link with your main program.
 
 [[x86-portable-include]]
 === Using an Include File
 
 If you are releasing your software as (or with) source code, you can use macros and place them in a separate file, which you include in your code.
 
 Porters of your software will simply write a new include file.
 No library or external object file is necessary, yet your code is portable without any need to edit the code.
 
 [NOTE]
 ====
 This is the approach we will use throughout this chapter.
 We will name our include file [.filename]#system.inc#, and add to it whenever we deal with a new system call.
 ====
 
 We can start our [.filename]#system.inc# by declaring the standard file descriptors:
 
 [.programlisting]
 ....
 %define	stdin	0
 %define	stdout	1
 %define	stderr	2
 ....
 
 Next, we create a symbolic name for each system call:
 
 [.programlisting]
 ....
 %define	SYS_nosys	0
 %define	SYS_exit	1
 %define	SYS_fork	2
 %define	SYS_read	3
 %define	SYS_write	4
 ; [etc...]
 ....
 
 We add a short, non-global procedure with a long name, so we do not accidentally reuse the name in our code:
 
 [.programlisting]
 ....
 section	.text
 align 4
 access.the.bsd.kernel:
 	int	80h
 	ret
 ....
 
 We create a macro which takes one argument, the syscall number:
 
 [.programlisting]
 ....
 %macro	system	1
 	mov	eax, %1
 	call	access.the.bsd.kernel
 %endmacro
 ....
 
 Finally, we create macros for each syscall.
 These macros take no arguments.
 
 [.programlisting]
 ....
 %macro	sys.exit	0
 	system	SYS_exit
 %endmacro
 
 %macro	sys.fork	0
 	system	SYS_fork
 %endmacro
 
 %macro	sys.read	0
 	system	SYS_read
 %endmacro
 
 %macro	sys.write	0
 	system	SYS_write
 %endmacro
 
 ; [etc...]
 ....
 
 Go ahead, enter it into your editor and save it as [.filename]#system.inc#.
 We will add more to it as we discuss more syscalls.
 
 [[x86-first-program]]
 == Our First Program
 
 We are now ready for our first program, the mandatory Hello, World!
 
 [.programlisting]
 ....
 1:	%include	'system.inc'
  2:
  3:	section	.data
  4:	hello	db	'Hello, World!', 0Ah
  5:	hbytes	equ	$-hello
  6:
  7:	section	.text
  8:	global	_start
  9:	_start:
 10:	push	dword hbytes
 11:	push	dword hello
 12:	push	dword stdout
 13:	sys.write
 14:
 15:	push	dword 0
 16:	sys.exit
 ....
 
 Here is what it does: Line 1 includes the defines, the macros, and the code from [.filename]#system.inc#.
 
 Lines 3-5 are the data: Line 3 starts the data section/segment.
 Line 4 contains the string "Hello, World!" followed by a new line (`0Ah`).
 Line 5 creates a constant that contains the length of the string from line 4 in bytes.
 
 Lines 7-16 contain the code.
 Note that FreeBSD uses the _elf_ file format for its executables, which requires every program to start at the point labeled `_start` (or, more precisely, the linker expects that).
 This label has to be global.
 
 Lines 10-13 ask the system to write `hbytes` bytes of the `hello` string to `stdout`.
 
 Lines 15-16 ask the system to end the program with the return value of `0`.
 The `SYS_exit` syscall never returns, so the code ends there.
 
 [NOTE]
 ====
 If you have come to UNIX(R) from MS-DOS(R) assembly language background, you may be used to writing directly to the video hardware.
 You will never have to worry about this in FreeBSD, or any other flavor of UNIX(R).
 As far as you are concerned, you are writing to a file known as [.filename]#stdout#.
 This can be the video screen, or a telnet terminal, or an actual file, or even the input of another program.
 Which one it is, is for the system to figure out.
 ====
 
 [[x86-assemble-1]]
 === Assembling the Code
 
 Type the code (except the line numbers) in an editor, and save it in a file named [.filename]#hello.asm#.
 You need nasm to assemble it.
 
 [[x86-get-nasm]]
 ==== Installing nasm
 
 If you do not have nasm, type:
 
 [source,shell]
 ....
 % su
 Password:your root password
 # cd /usr/ports/devel/nasm
 # make install
 # exit
 %
 ....
 
 You may type `make install clean` instead of just `make install` if you do not want to keep nasm source code.
 
 Either way, FreeBSD will automatically download nasm from the Internet, compile it, and install it on your system.
 
 [NOTE]
 ====
 If your system is not FreeBSD, you need to get nasm from its https://sourceforge.net/projects/nasm[home page].
 You can still use it to assemble FreeBSD code.
 ====
 
 Now you can assemble, link, and run the code:
 
 [source,shell]
 ....
 % nasm -f elf hello.asm
 % ld -s -o hello hello.o
 % ./hello
 Hello, World!
 %
 ....
 
 [[x86-unix-filters]]
 == Writing UNIX(R) Filters
 
 A common type of UNIX(R) application is a filter-a program that reads data from the [.filename]#stdin#, processes it somehow, then writes the result to [.filename]#stdout#.
 
 In this chapter, we shall develop a simple filter, and learn how to read from [.filename]#stdin# and write to [.filename]#stdout#.
 This filter will convert each byte of its input into a hexadecimal number followed by a blank space.
 
 [.programlisting]
 ....
 %include	'system.inc'
 
 section	.data
 hex	db	'0123456789ABCDEF'
 buffer	db	0, 0, ' '
 
 section	.text
 global	_start
 _start:
 	; read a byte from stdin
 	push	dword 1
 	push	dword buffer
 	push	dword stdin
 	sys.read
 	add	esp, byte 12
 	or	eax, eax
 	je	.done
 
 	; convert it to hex
 	movzx	eax, byte [buffer]
 	mov	edx, eax
 	shr	dl, 4
 	mov	dl, [hex+edx]
 	mov	[buffer], dl
 	and	al, 0Fh
 	mov	al, [hex+eax]
 	mov	[buffer+1], al
 
 	; print it
 	push	dword 3
 	push	dword buffer
 	push	dword stdout
 	sys.write
 	add	esp, byte 12
 	jmp	short _start
 
 .done:
 	push	dword 0
 	sys.exit
 ....
 
 In the data section we create an array called `hex`.
 It contains the 16 hexadecimal digits in ascending order.
 The array is followed by a buffer which we will use for both input and output.
 The first two bytes of the buffer are initially set to `0`.
 This is where we will write the two hexadecimal digits (the first byte also is where we will read the input).
 The third byte is a space.
 
 The code section consists of four parts: Reading the byte, converting it to a hexadecimal number, writing the result, and eventually exiting the program.
 
 To read the byte, we ask the system to read one byte from [.filename]#stdin#, and store it in the first byte of the `buffer`.
 The system returns the number of bytes read in `EAX`.
 This will be `1` while data is coming, or `0`, when no more input data is available.
 Therefore, we check the value of `EAX`.
 If it is `0`, we jump to `.done`, otherwise we continue.
 
 [NOTE]
 ====
 For simplicity sake, we are ignoring the possibility of an error condition at this time.
 ====
 
 The hexadecimal conversion reads the byte from the `buffer` into `EAX`, or actually just `AL`, while clearing the remaining bits of `EAX` to zeros.
 We also copy the byte to `EDX` because we need to convert the upper four bits (nibble) separately from the lower four bits.
 We store the result in the first two bytes of the buffer.
 
 Next, we ask the system to write the three bytes of the buffer, i.e., the two hexadecimal digits and the blank space, to [.filename]#stdout#.
 We then jump back to the beginning of the program and process the next byte.
 
 Once there is no more input left, we ask the system to exit our program, returning a zero, which is the traditional value meaning the program was successful.
 
 Go ahead, and save the code in a file named [.filename]#hex.asm#, then type the following (the `^D` means press the control key and type `D` while holding the control key down):
 
 [source,shell]
 ....
 % nasm -f elf hex.asm
 % ld -s -o hex hex.o
 % ./hex
 Hello, World!
 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A Here I come!
 48 65 72 65 20 49 20 63 6F 6D 65 21 0A ^D %
 ....
 
 [NOTE]
 ====
 If you are migrating to UNIX(R) from MS-DOS(R), you may be wondering why each line ends with `0A` instead of `0D 0A`.
 This is because UNIX(R) does not use the cr/lf convention, but a "new line" convention, which is `0A` in hexadecimal.
 ====
 
 Can we improve this? Well, for one, it is a bit confusing because once we have converted a line of text,
 our input no longer starts at the beginning of the line.
 We can modify it to print a new line instead of a space after each `0A`:
 
 [.programlisting]
 ....
 %include	'system.inc'
 
 section	.data
 hex	db	'0123456789ABCDEF'
 buffer	db	0, 0, ' '
 
 section	.text
 global	_start
 _start:
 	mov	cl, ' '
 
 .loop:
 	; read a byte from stdin
 	push	dword 1
 	push	dword buffer
 	push	dword stdin
 	sys.read
 	add	esp, byte 12
 	or	eax, eax
 	je	.done
 
 	; convert it to hex
 	movzx	eax, byte [buffer]
 	mov	[buffer+2], cl
 	cmp	al, 0Ah
 	jne	.hex
 	mov	[buffer+2], al
 
 .hex:
 	mov	edx, eax
 	shr	dl, 4
 	mov	dl, [hex+edx]
 	mov	[buffer], dl
 	and	al, 0Fh
 	mov	al, [hex+eax]
 	mov	[buffer+1], al
 
 	; print it
 	push	dword 3
 	push	dword buffer
 	push	dword stdout
 	sys.write
 	add	esp, byte 12
 	jmp	short .loop
 
 .done:
 	push	dword 0
 	sys.exit
 ....
 
 We have stored the space in the `CL` register.
 We can do this safely because, unlike Microsoft(R) Windows(R), UNIX(R) system calls do not modify the value of any register they do not use to return a value in.
 
 That means we only need to set `CL` once.
 We have, therefore, added a new label `.loop` and jump to it for the next byte instead of jumping at `_start`.
 We have also added the `.hex` label so we can either have a blank space or a new line as the third byte of the `buffer`.
 
 Once you have changed [.filename]#hex.asm# to reflect these changes, type:
 
 [source,shell]
 ....
 % nasm -f elf hex.asm
 % ld -s -o hex hex.o
 % ./hex
 Hello, World!
 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A
 Here I come!
 48 65 72 65 20 49 20 63 6F 6D 65 21 0A
 ^D %
 ....
 
 That looks better.
 But this code is quite inefficient! We are making a system call for every single byte twice (once to read it, another time to write the output).
 
 [[x86-buffered-io]]
 == Buffered Input and Output
 
 We can improve the efficiency of our code by buffering our input and output.
 We create an input buffer and read a whole sequence of bytes at one time.
 Then we fetch them one by one from the buffer.
 
 We also create an output buffer. We store our output in it until it is full.
 At that time we ask the kernel to write the contents of the buffer to [.filename]#stdout#.
 
 The program ends when there is no more input.
 But we still need to ask the kernel to write the contents of our output buffer to [.filename]#stdout# one last time, otherwise some of our output would make it to the output buffer, but never be sent out.
 Do not forget that, or you will be wondering why some of your output is missing.
 
 [.programlisting]
 ....
 %include	'system.inc'
 
 %define	BUFSIZE	2048
 
 section	.data
 hex	db	'0123456789ABCDEF'
 
 section .bss
 ibuffer	resb	BUFSIZE
 obuffer	resb	BUFSIZE
 
 section	.text
 global	_start
 _start:
 	sub	eax, eax
 	sub	ebx, ebx
 	sub	ecx, ecx
 	mov	edi, obuffer
 
 .loop:
 	; read a byte from stdin
 	call	getchar
 
 	; convert it to hex
 	mov	dl, al
 	shr	al, 4
 	mov	al, [hex+eax]
 	call	putchar
 
 	mov	al, dl
 	and	al, 0Fh
 	mov	al, [hex+eax]
 	call	putchar
 
 	mov	al, ' '
 	cmp	dl, 0Ah
 	jne	.put
 	mov	al, dl
 
 .put:
 	call	putchar
 	jmp	short .loop
 
 align 4
 getchar:
 	or	ebx, ebx
 	jne	.fetch
 
 	call	read
 
 .fetch:
 	lodsb
 	dec	ebx
 	ret
 
 read:
 	push	dword BUFSIZE
 	mov	esi, ibuffer
 	push	esi
 	push	dword stdin
 	sys.read
 	add	esp, byte 12
 	mov	ebx, eax
 	or	eax, eax
 	je	.done
 	sub	eax, eax
 	ret
 
 align 4
 .done:
 	call	write		; flush output buffer
 	push	dword 0
 	sys.exit
 
 align 4
 putchar:
 	stosb
 	inc	ecx
 	cmp	ecx, BUFSIZE
 	je	write
 	ret
 
 align 4
 write:
 	sub	edi, ecx	; start of buffer
 	push	ecx
 	push	edi
 	push	dword stdout
 	sys.write
 	add	esp, byte 12
 	sub	eax, eax
 	sub	ecx, ecx	; buffer is empty now
 	ret
 ....
 
 We now have a third section in the source code, named `.bss`.
 This section is not included in our executable file, and, therefore, cannot be initialized.
 We use `resb` instead of `db`.
 It simply reserves the requested size of uninitialized memory for our use.
 
 We take advantage of the fact that the system does not modify the registers:
 We use registers for what, otherwise, would have to be global variables stored in the `.data` section.
 This is also why the UNIX(R) convention of passing parameters to system calls on the stack is superior to the Microsoft convention of passing them in the registers: We can keep the registers for our own use.
 
 We use `EDI` and `ESI` as pointers to the next byte to be read from or written to.
 We use `EBX` and `ECX` to keep count of the number of bytes in the two buffers,
 so we know when to dump the output to, or read more input from, the system.
 
 Let us see how it works now:
 
 [source,shell]
 ....
 % nasm -f elf hex.asm
 % ld -s -o hex hex.o
 % ./hex
 Hello, World!
 Here I come!
 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A
 48 65 72 65 20 49 20 63 6F 6D 65 21 0A
 ^D %
 ....
 
 Not what you expected? The program did not print the output until we pressed `^D`.
 That is easy to fix by inserting three lines of code to write the output every time we have converted a new line to `0A`.
 I have marked the three lines with > (do not copy the > in your [.filename]#hex.asm#).
 
 [.programlisting]
 ....
 %include	'system.inc'
 
 %define	BUFSIZE	2048
 
 section	.data
 hex	db	'0123456789ABCDEF'
 
 section .bss
 ibuffer	resb	BUFSIZE
 obuffer	resb	BUFSIZE
 
 section	.text
 global	_start
 _start:
 	sub	eax, eax
 	sub	ebx, ebx
 	sub	ecx, ecx
 	mov	edi, obuffer
 
 .loop:
 	; read a byte from stdin
 	call	getchar
 
 	; convert it to hex
 	mov	dl, al
 	shr	al, 4
 	mov	al, [hex+eax]
 	call	putchar
 
 	mov	al, dl
 	and	al, 0Fh
 	mov	al, [hex+eax]
 	call	putchar
 
 	mov	al, ' '
 	cmp	dl, 0Ah
 	jne	.put
 	mov	al, dl
 
 .put:
 	call	putchar
 >	cmp	al, 0Ah
 >	jne	.loop
 >	call	write
 	jmp	short .loop
 
 align 4
 getchar:
 	or	ebx, ebx
 	jne	.fetch
 
 	call	read
 
 .fetch:
 	lodsb
 	dec	ebx
 	ret
 
 read:
 	push	dword BUFSIZE
 	mov	esi, ibuffer
 	push	esi
 	push	dword stdin
 	sys.read
 	add	esp, byte 12
 	mov	ebx, eax
 	or	eax, eax
 	je	.done
 	sub	eax, eax
 	ret
 
 align 4
 .done:
 	call	write		; flush output buffer
 	push	dword 0
 	sys.exit
 
 align 4
 putchar:
 	stosb
 	inc	ecx
 	cmp	ecx, BUFSIZE
 	je	write
 	ret
 
 align 4
 write:
 	sub	edi, ecx	; start of buffer
 	push	ecx
 	push	edi
 	push	dword stdout
 	sys.write
 	add	esp, byte 12
 	sub	eax, eax
 	sub	ecx, ecx	; buffer is empty now
 	ret
 ....
 
 Now, let us see how it works:
 
 [source,shell]
 ....
 % nasm -f elf hex.asm
 % ld -s -o hex hex.o
 % ./hex
 Hello, World!
 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A
 Here I come!
 48 65 72 65 20 49 20 63 6F 6D 65 21 0A
 ^D %
 ....
 
 Not bad for a 644-byte executable, is it!
 
 [NOTE]
 ====
 This approach to buffered input/output still contains a hidden danger.
 I will discuss-and fix-it later, when I talk about the <<x86-buffered-dark-side,dark side of buffering>>.
 ====
 
 [[x86-ungetc]]
 === How to Unread a Character
 
 [WARNING]
 ====
 This may be a somewhat advanced topic, mostly of interest to programmers familiar with the theory of compilers.
 If you wish, you may <<x86-command-line,skip to the next section>>, and perhaps read this later.
 ====
 
 While our sample program does not require it, more sophisticated filters often need to look ahead.
 In other words, they may need to see what the next character is (or even several characters).
 If the next character is of a certain value, it is part of the token currently being processed.
 Otherwise, it is not.
 
 For example, you may be parsing the input stream for a textual string (e.g., when implementing a language compiler):
 If a character is followed by another character, or perhaps a digit, it is part of the token you are processing.
 If it is followed by white space, or some other value, then it is not part of the current token.
 
 This presents an interesting problem: How to return the next character back to the input stream, so it can be read again later?
 
 One possible solution is to store it in a character variable, then set a flag.
 We can modify `getchar` to check the flag, and if it is set, fetch the byte from that variable instead of the input buffer, and reset the flag.
 But, of course, that slows us down.
 
 The C language has an `ungetc()` function, just for that purpose.
 Is there a quick way to implement it in our code?
 I would like you to scroll back up and take a look at the `getchar` procedure and see if you can find a nice and fast solution before reading the next paragraph.
 Then come back here and see my own solution.
 
 The key to returning a character back to the stream is in how we are getting the characters to start with:
 
 First we check if the buffer is empty by testing the value of `EBX`.
 If it is zero, we call the `read` procedure.
 
 If we do have a character available, we use `lodsb`, then decrease the value of `EBX`.
 The `lodsb` instruction is effectively identical to:
 
 [.programlisting]
 ....
 mov	al, [esi]
 	inc	esi
 ....
 
 The byte we have fetched remains in the buffer until the next time `read` is called.
 We do not know when that happens, but we do know it will not happen until the next call to `getchar`.
 Hence, to "return" the last-read byte back to the stream, all we have to do is decrease the value of `ESI` and increase the value of `EBX`:
 
 [.programlisting]
 ....
 ungetc:
 	dec	esi
 	inc	ebx
 	ret
 ....
 
 But, be careful! We are perfectly safe doing this if our look-ahead is at most one character at a time.
 If we are examining more than one upcoming character and call `ungetc` several times in a row, it will work most of the time, but not all the time (and will be tough to debug). Why?
 
 Because as long as `getchar` does not have to call `read`, all of the pre-read bytes are still in the buffer, and our `ungetc` works without a glitch.
 But the moment `getchar` calls `read`, the contents of the buffer change.
 
 We can always rely on `ungetc` working properly on the last character we have read with `getchar`, but not on anything we have read before that.
 
 If your program reads more than one byte ahead, you have at least two choices:
 
 If possible, modify the program so it only reads one byte ahead.
 This is the simplest solution.
 
 If that option is not available, first of all determine the maximum number of characters your program needs to return to the input stream at one time.
 Increase that number slightly, just to be sure, preferably to a multiple of 16-so it aligns nicely.
 Then modify the `.bss` section of your code, and create a small "spare" buffer right before your input buffer, something like this:
 
 [.programlisting]
 ....
 section	.bss
 	resb	16	; or whatever the value you came up with
 ibuffer	resb	BUFSIZE
 obuffer	resb	BUFSIZE
 ....
 
 You also need to modify your `ungetc` to pass the value of the byte to unget in `AL`:
 
 [.programlisting]
 ....
 ungetc:
 	dec	esi
 	inc	ebx
 	mov	[esi], al
 	ret
 ....
 
 With this modification, you can call `ungetc` up to 17 times in a row safely (the first call will still be within the buffer, the remaining 16 may be either within the buffer or within the "spare").
 
 [[x86-command-line]]
 == Command Line Arguments
 
 Our hex program will be more useful if it can read the names of an input and output file from its command line, i.e., if it can process the command line arguments.
 But... Where are they?
 
 Before a UNIX(R) system starts a program, it ``push``es some data on the stack, then jumps at the `_start` label of the program.
 Yes, I said jumps, not calls.
 That means the data can be accessed by reading `[esp+offset]`, or by simply ``pop``ping it.
 
 The value at the top of the stack contains the number of command line arguments.
 It is traditionally called `argc`, for "argument count."
 
 Command line arguments follow next, all `argc` of them.
 These are typically referred to as `argv`, for "argument value(s)." That is, we get `argv[0]`, `argv[1]`, `...`, `argv[argc-1]`.
 These are not the actual arguments, but pointers to arguments, i.e., memory addresses of the actual arguments.
 The arguments themselves are NUL-terminated character strings.
 
 The `argv` list is followed by a NULL pointer, which is simply a `0`. There is more, but this is enough for our purposes right now.
 
 [NOTE]
 ====
 If you have come from the MS-DOS(R) programming environment, the main difference is that each argument is in a separate string.
 The second difference is that there is no practical limit on how many arguments there can be.
 ====
 
 Armed with this knowledge, we are almost ready for the next version of [.filename]#hex.asm#.
 First, however, we need to add a few lines to [.filename]#system.inc#:
 
 First, we need to add two new entries to our list of system call numbers:
 
 [.programlisting]
 ....
 %define	SYS_open	5
 %define	SYS_close	6
 ....
 
 Then we add two new macros at the end of the file:
 
 [.programlisting]
 ....
 %macro	sys.open	0
 	system	SYS_open
 %endmacro
 
 %macro	sys.close	0
 	system	SYS_close
 %endmacro
 ....
 
 Here, then, is our modified source code:
 
 [.programlisting]
 ....
 %include	'system.inc'
 
 %define	BUFSIZE	2048
 
 section	.data
 fd.in	dd	stdin
 fd.out	dd	stdout
 hex	db	'0123456789ABCDEF'
 
 section .bss
 ibuffer	resb	BUFSIZE
 obuffer	resb	BUFSIZE
 
 section	.text
 align 4
 err:
 	push	dword 1		; return failure
 	sys.exit
 
 align 4
 global	_start
 _start:
 	add	esp, byte 8	; discard argc and argv[0]
 
 	pop	ecx
 	jecxz	.init		; no more arguments
 
 	; ECX contains the path to input file
 	push	dword 0		; O_RDONLY
 	push	ecx
 	sys.open
 	jc	err		; open failed
 
 	add	esp, byte 8
 	mov	[fd.in], eax
 
 	pop	ecx
 	jecxz	.init		; no more arguments
 
 	; ECX contains the path to output file
 	push	dword 420	; file mode (644 octal)
 	push	dword 0200h | 0400h | 01h
 	; O_CREAT | O_TRUNC | O_WRONLY
 	push	ecx
 	sys.open
 	jc	err
 
 	add	esp, byte 12
 	mov	[fd.out], eax
 
 .init:
 	sub	eax, eax
 	sub	ebx, ebx
 	sub	ecx, ecx
 	mov	edi, obuffer
 
 .loop:
 	; read a byte from input file or stdin
 	call	getchar
 
 	; convert it to hex
 	mov	dl, al
 	shr	al, 4
 	mov	al, [hex+eax]
 	call	putchar
 
 	mov	al, dl
 	and	al, 0Fh
 	mov	al, [hex+eax]
 	call	putchar
 
 	mov	al, ' '
 	cmp	dl, 0Ah
 	jne	.put
 	mov	al, dl
 
 .put:
 	call	putchar
 	cmp	al, dl
 	jne	.loop
 	call	write
 	jmp	short .loop
 
 align 4
 getchar:
 	or	ebx, ebx
 	jne	.fetch
 
 	call	read
 
 .fetch:
 	lodsb
 	dec	ebx
 	ret
 
 read:
 	push	dword BUFSIZE
 	mov	esi, ibuffer
 	push	esi
 	push	dword [fd.in]
 	sys.read
 	add	esp, byte 12
 	mov	ebx, eax
 	or	eax, eax
 	je	.done
 	sub	eax, eax
 	ret
 
 align 4
 .done:
 	call	write		; flush output buffer
 
 	; close files
 	push	dword [fd.in]
 	sys.close
 
 	push	dword [fd.out]
 	sys.close
 
 	; return success
 	push	dword 0
 	sys.exit
 
 align 4
 putchar:
 	stosb
 	inc	ecx
 	cmp	ecx, BUFSIZE
 	je	write
 	ret
 
 align 4
 write:
 	sub	edi, ecx	; start of buffer
 	push	ecx
 	push	edi
 	push	dword [fd.out]
 	sys.write
 	add	esp, byte 12
 	sub	eax, eax
 	sub	ecx, ecx	; buffer is empty now
 	ret
 ....
 
 In our `.data` section we now have two new variables, `fd.in` and `fd.out`.
 We store the input and output file descriptors here.
 
 In the `.text` section we have replaced the references to `stdin` and `stdout` with `[fd.in]` and `[fd.out]`.
 
 The `.text` section now starts with a simple error handler, which does nothing but exit the program with a return value of `1`.
 The error handler is before `_start` so we are within a short distance from where the errors occur.
 
 Naturally, the program execution still begins at `_start`.
 First, we remove `argc` and `argv[0]` from the stack: They are of no interest to us (in this program, that is).
 
 We pop `argv[1]` to `ECX`.
 This register is particularly suited for pointers, as we can handle NULL pointers with `jecxz`.
 If `argv[1]` is not NULL, we try to open the file named in the first argument.
 Otherwise, we continue the program as before: Reading from `stdin`, writing to `stdout`.
 If we fail to open the input file (e.g., it does not exist), we jump to the error handler and quit.
 
 If all went well, we now check for the second argument.
 If it is there, we open the output file.
 Otherwise, we send the output to `stdout`.
 If we fail to open the output file (e.g., it exists and we do not have the write permission), we, again, jump to the error handler.
 
 The rest of the code is the same as before, except we close the input and output files before exiting, and, as mentioned, we use `[fd.in]` and `[fd.out]`.
 
 Our executable is now a whopping 768 bytes long.
 
 Can we still improve it? Of course! Every program can be improved.
 Here are a few ideas of what we could do:
 
 * Have our error handler print a message to `stderr`.
 * Add error handlers to the `read` and `write` functions.
 * Close `stdin` when we open an input file, `stdout` when we open an output file.
 * Add command line switches, such as `-i` and `-o`, so we can list the input and output files in any order, or perhaps read from `stdin` and write to a file.
 * Print a usage message if command line arguments are incorrect.
 
 I shall leave these enhancements as an exercise to the reader: You already know everything you need to know to implement them.
 
 [[x86-environment]]
 == UNIX(R) Environment
 
 An important UNIX(R) concept is the environment, which is defined by _environment variables_.
 Some are set by the system, others by you, yet others by the shell, or any program that loads another program.
 
 [[x86-find-environment]]
 === How to Find Environment Variables
 
 I said earlier that when a program starts executing, the stack contains `argc` followed by the NULL-terminated `argv` array, followed by something else.
 The "something else" is the _environment_, or, to be more precise, a NULL-terminated array of pointers to _environment variables_.
 This is often referred to as `env`.
 
 The structure of `env` is the same as that of `argv`, a list of memory addresses followed by a NULL (`0`).
 In this case, there is no `"envc"`-we figure out where the array ends by searching for the final NULL.
 
 The variables usually come in the `name=value` format, but sometimes the `=value` part may be missing.
 We need to account for that possibility.
 
 [[x86-webvar]]
 === webvars
 
 I could just show you some code that prints the environment the same way the UNIX(R) env command does.
 But I thought it would be more interesting to write a simple assembly language CGI utility.
 
 [[x86-cgi]]
 ==== CGI: a Quick Overview
 
 I have a http://www.whizkidtech.redprince.net/cgi-bin/tutorial[detailed CGI tutorial] on my web site, but here is a very quick overview of CGI:
 
 * The web server communicates with the CGI program by setting _environment variables_.
 * The CGI program sends its output to [.filename]#stdout#. The web server reads it from there.
 * It must start with an HTTP header followed by two blank lines.
 * It then prints the HTML code, or whatever other type of data it is producing.
 
 [NOTE]
 ====
 While certain _environment variables_ use standard names, others vary, depending on the web server.
 That makes webvars quite a useful diagnostic tool.
 ====
 
 [[x86-webvars-the-code]]
 ==== The Code
 
 Our webvars program, then, must send out the HTTP header followed by some HTML mark-up.
 It then must read the _environment variables_ one by one and send them out as part of the HTML page.
 
 The code follows.
 I placed comments and explanations right inside the code:
 
 [.programlisting]
 ....
 ;;;;;;; webvars.asm ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;
 ; Copyright (c) 2000 G. Adam Stanislav
 ; All rights reserved.
 ;
 ; Redistribution and use in source and binary forms, with or without
 ; modification, are permitted provided that the following conditions
 ; are met:
 ; 1. Redistributions of source code must retain the above copyright
 ;    notice, this list of conditions and the following disclaimer.
 ; 2. Redistributions in binary form must reproduce the above copyright
 ;    notice, this list of conditions and the following disclaimer in the
 ;    documentation and/or other materials provided with the distribution.
 ;
 ; THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 ; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 ; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 ; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 ; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 ; OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 ; HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 ; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 ; OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 ; SUCH DAMAGE.
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;
 ; Version 1.0
 ;
 ; Started:	 8-Dec-2000
 ; Updated:	 8-Dec-2000
 ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 %include	'system.inc'
 
 section	.data
 http	db	'Content-type: text/html', 0Ah, 0Ah
 	db	'<?xml version="1.0" encoding="utf-8"?>', 0Ah
 	db	'<!DOCTYPE html PUBLIC "-//W3C/DTD XHTML Strict//EN" '
 	db	'"DTD/xhtml1-strict.dtd">', 0Ah
 	db	'<html xmlns="http://www.w3.org/1999/xhtml" '
 	db	'xml.lang="en" lang="en">', 0Ah
 	db	'<head>', 0Ah
 	db	'<title>Web Environment</title>', 0Ah
 	db	'<meta name="author" content="G. Adam Stanislav" />', 0Ah
 	db	'</head>', 0Ah, 0Ah
 	db	'<body bgcolor="#ffffff" text="#000000" link="#0000ff" '
 	db	'vlink="#840084" alink="#0000ff">', 0Ah
 	db	'<div class="webvars">', 0Ah
 	db	'<h1>Web Environment</h1>', 0Ah
 	db	'<p>The following <b>environment variables</b> are defined '
 	db	'on this web server:</p>', 0Ah, 0Ah
 	db	'<table align="center" width="80" border="0" cellpadding="10" '
 	db	'cellspacing="0" class="webvars">', 0Ah
 httplen	equ	$-http
 left	db	'<tr>', 0Ah
 	db	'<td class="name"><tt>'
 leftlen	equ	$-left
 middle	db	'</tt></td>', 0Ah
 	db	'<td class="value"><tt><b>'
 midlen	equ	$-middle
 undef	db	'<i>(undefined)</i>'
 undeflen	equ	$-undef
 right	db	'</b></tt></td>', 0Ah
 	db	'</tr>', 0Ah
 rightlen	equ	$-right
 wrap	db	'</table>', 0Ah
 	db	'</div>', 0Ah
 	db	'</body>', 0Ah
 	db	'</html>', 0Ah, 0Ah
 wraplen	equ	$-wrap
 
 section	.text
 global	_start
 _start:
 	; First, send out all the http and xhtml stuff that is
 	; needed before we start showing the environment
 	push	dword httplen
 	push	dword http
 	push	dword stdout
 	sys.write
 
 	; Now find how far on the stack the environment pointers
 	; are. We have 12 bytes we have pushed before "argc"
 	mov	eax, [esp+12]
 
 	; We need to remove the following from the stack:
 	;
 	;	The 12 bytes we pushed for sys.write
 	;	The  4 bytes of argc
 	;	The EAX*4 bytes of argv
 	;	The  4 bytes of the NULL after argv
 	;
 	; Total:
 	;	20 + eax * 4
 	;
 	; Because stack grows down, we need to ADD that many bytes
 	; to ESP.
 	lea	esp, [esp+20+eax*4]
 	cld		; This should already be the case, but let's be sure.
 
 	; Loop through the environment, printing it out
 .loop:
 	pop	edi
 	or	edi, edi	; Done yet?
 	je	near .wrap
 
 	; Print the left part of HTML
 	push	dword leftlen
 	push	dword left
 	push	dword stdout
 	sys.write
 
 	; It may be tempting to search for the '=' in the env string next.
 	; But it is possible there is no '=', so we search for the
 	; terminating NUL first.
 	mov	esi, edi	; Save start of string
 	sub	ecx, ecx
 	not	ecx		; ECX = FFFFFFFF
 	sub	eax, eax
 repne	scasb
 	not	ecx		; ECX = string length + 1
 	mov	ebx, ecx	; Save it in EBX
 
 	; Now is the time to find '='
 	mov	edi, esi	; Start of string
 	mov	al, '='
 repne	scasb
 	not	ecx
 	add	ecx, ebx	; Length of name
 
 	push	ecx
 	push	esi
 	push	dword stdout
 	sys.write
 
 	; Print the middle part of HTML table code
 	push	dword midlen
 	push	dword middle
 	push	dword stdout
 	sys.write
 
 	; Find the length of the value
 	not	ecx
 	lea	ebx, [ebx+ecx-1]
 
 	; Print "undefined" if 0
 	or	ebx, ebx
 	jne	.value
 
 	mov	ebx, undeflen
 	mov	edi, undef
 
 .value:
 	push	ebx
 	push	edi
 	push	dword stdout
 	sys.write
 
 	; Print the right part of the table row
 	push	dword rightlen
 	push	dword right
 	push	dword stdout
 	sys.write
 
 	; Get rid of the 60 bytes we have pushed
 	add	esp, byte 60
 
 	; Get the next variable
 	jmp	.loop
 
 .wrap:
 	; Print the rest of HTML
 	push	dword wraplen
 	push	dword wrap
 	push	dword stdout
 	sys.write
 
 	; Return success
 	push	dword 0
 	sys.exit
 ....
 
 This code produces a 1,396-byte executable.
 Most of it is data, i.e., the HTML mark-up we need to send out.
 
 Assemble and link it as usual:
 
 [source,shell]
 ....
 % nasm -f elf webvars.asm
 % ld -s -o webvars webvars.o
 ....
 
 To use it, you need to upload [.filename]#webvars# to your web server.
 Depending on how your web server is set up, you may have to store it in a special [.filename]#cgi-bin# directory, or perhaps rename it with a [.filename]#.cgi# extension.
 
 Then you need to use your browser to view its output.
 To see its output on my web server, please go to http://www.int80h.org/webvars/[http://www.int80h.org/webvars/].
 If curious about the additional environment variables present in a password protected web directory, go to http://www.int80h.org/private/[http://www.int80h.org/private/], using the name `asm` and password `programmer`.
 
 [[x86-files]]
 == Working with Files
 
 We have already done some basic file work: We know how to open and close them, how to read and write them using buffers.
 But UNIX(R) offers much more functionality when it comes to files.
 We will examine some of it in this section, and end up with a nice file conversion utility.
 
 Indeed, let us start at the end, that is, with the file conversion utility.
 It always makes programming easier when we know from the start what the end product is supposed to do.
 
 One of the first programs I wrote for UNIX(R) was link:ftp://ftp.int80h.org/unix/tuc/[tuc], a text-to-UNIX(R) file converter.
 It converts a text file from other operating systems to a UNIX(R) text file.
 In other words, it changes from different kind of line endings to the newline convention of UNIX(R).
 It saves the output in a different file.
 Optionally, it converts a UNIX(R) text file to a DOS text file.
 
 I have used tuc extensively, but always only to convert from some other OS to UNIX(R), never the other way.
 I have always wished it would just overwrite the file instead of me having to send the output to a different file.
 Most of the time, I end up using it like this:
 
 [source,shell]
 ....
 % tuc myfile tempfile
 % mv tempfile myfile
 ....
 
 It would be nice to have a ftuc, i.e., _fast tuc_, and use it like this:
 
 [source,shell]
 ....
 % ftuc myfile
 ....
 
 In this chapter, then, we will write ftuc in assembly language (the original tuc is in C), and study various file-oriented kernel services in the process.
 
 At first sight, such a file conversion is very simple: All you have to do is strip the carriage returns, right?
 
 If you answered yes, think again: That approach will work most of the time (at least with MS DOS text files), but will fail occasionally.
 
 The problem is that not all non UNIX(R) text files end their line with the carriage return / line feed sequence.
 Some use carriage returns without line feeds.
 Others combine several blank lines into a single carriage return followed by several line feeds.
 And so on.
 
 A text file converter, then, must be able to handle any possible line endings:
 
 * carriage return / line feed
 * carriage return
 * line feed / carriage return
 * line feed
 
 It should also handle files that use some kind of a combination of the above (e.g., carriage return followed by several line feeds).
 
 [[x86-finite-state-machine]]
 === Finite State Machine
 
 The problem is easily solved by the use of a technique called _finite state machine_, originally developed by the designers of digital electronic circuits.
 A _finite state machine_ is a digital circuit whose output is dependent not only on its input but on its previous input, i.e., on its state.
 The microprocessor is an example of a _finite state machine_: Our assembly language code is assembled to machine language in which some assembly language code produces a single byte of machine language, while others produce several bytes.
 As the microprocessor fetches the bytes from the memory one by one, some of them simply change its state rather than produce some output.
 When all the bytes of the op code are fetched, the microprocessor produces some output, or changes the value of a register, etc.
 
 Because of that, all software is essentially a sequence of state instructions for the microprocessor.
 Nevertheless, the concept of _finite state machine_ is useful in software design as well.
 
 Our text file converter can be designer as a _finite state machine_ with three possible states.
 We could call them states 0-2, but it will make our life easier if we give them symbolic names:
 
 * ordinary
 * cr
 * lf
 
 Our program will start in the ordinary state. During this state, the program action depends on its input as follows:
 
 * If the input is anything other than a carriage return or line feed, the input is simply passed on to the output.
 The state remains unchanged.
 * If the input is a carriage return, the state is changed to cr.
 The input is then discarded, i.e., no output is made.
 * If the input is a line feed, the state is changed to lf.
 The input is then discarded.
 
 Whenever we are in the cr state, it is because the last input was a carriage return, which was unprocessed.
 What our software does in this state again depends on the current input:
 
 * If the input is anything other than a carriage return or line feed, output a line feed, then output the input, then change the state to ordinary.
 * If the input is a carriage return, we have received two (or more) carriage returns in a row. We discard the input, we output a line feed, and leave the state unchanged.
 * If the input is a line feed, we output the line feed and change the state to ordinary. Note that this is not the same as the first case above - if we tried to combine them, we would be outputting two line feeds instead of one.
 
 Finally, we are in the lf state after we have received a line feed that was not preceded by a carriage return.
 This will happen when our file already is in UNIX(R) format, or whenever several lines in a row are expressed by a single carriage return followed by several line feeds, or when line ends with a line feed / carriage return sequence.
 Here is how we need to handle our input in this state:
 
 * If the input is anything other than a carriage return or line feed, we output a line feed, then output the input, then change the state to ordinary. This is exactly the same action as in the cr state upon receiving the same kind of input.
 * If the input is a carriage return, we discard the input, we output a line feed, then change the state to ordinary.
 * If the input is a line feed, we output the line feed, and leave the state unchanged.
 
 [[x86-final-state]]
 ==== The Final State
 
 The above _finite state machine_ works for the entire file, but leaves the possibility that the final line end will be ignored.
 That will happen whenever the file ends with a single carriage return or a single line feed.
 I did not think of it when I wrote tuc, just to discover that occasionally it strips the last line ending.
 
 This problem is easily fixed by checking the state after the entire file was processed.
 If the state is not ordinary, we simply need to output one last line feed.
 
 [NOTE]
 ====
 Now that we have expressed our algorithm as a _finite state machine_,
 we could easily design a dedicated digital electronic circuit (a "chip") to do the conversion for us.
 Of course, doing so would be considerably more expensive than writing an assembly language program.
 ====
 
 [[x86-tuc-counter]]
 ==== The Output Counter
 
 Because our file conversion program may be combining two characters into one, we need to use an output counter.
 We initialize it to `0`, and increase it every time we send a character to the output.
 At the end of the program, the counter will tell us what size we need to set the file to.
 
 [[x86-software-fsm]]
 === Implementing FSM in Software
 
 The hardest part of working with a _finite state machine_ is analyzing the problem and expressing it as a _finite state machine_.
 That accomplished, the software almost writes itself.
 
 In a high-level language, such as C, there are several main approaches.
 One is to use a `switch` statement which chooses what function should be run. For example,
 
 [.programlisting]
 ....
 switch (state) {
 	default:
 	case REGULAR:
 		regular(inputchar);
 		break;
 	case CR:
 		cr(inputchar);
 		break;
 	case LF:
 		lf(inputchar);
 		break;
 	}
 ....
 
 Another approach is by using an array of function pointers, something like this:
 
 [.programlisting]
 ....
 (output[state])(inputchar);
 ....
 
 Yet another is to have `state` be a function pointer, set to point at the appropriate function:
 
 [.programlisting]
 ....
 (*state)(inputchar);
 ....
 
 This is the approach we will use in our program because it is very easy to do in assembly language, and very fast, too.
 We will simply keep the address of the right procedure in `EBX`, and then just issue:
 
 [.programlisting]
 ....
 call	ebx
 ....
 
 This is possibly faster than hardcoding the address in the code because the microprocessor does not have to fetch the address from the memory-it is already stored in one of its registers.
 I said _possibly_ because with the caching modern microprocessors do, either way may be equally fast.
 
 [[memory-mapped-files]]
 === Memory Mapped Files
 
 Because our program works on a single file, we cannot use the approach that worked for us before, i.e.,
 to read from an input file and to write to an output file.
 
 UNIX(R) allows us to map a file, or a section of a file, into memory.
 To do that, we first need to open the file with the appropriate read/write flags.
 Then we use the `mmap` system call to map it into the memory.
 One nice thing about `mmap` is that it automatically works with virtual memory:
 We can map more of the file into the memory than we have physical memory available, yet still access it through regular memory op codes, such as `mov`, `lods`, and `stos`.
 Whatever changes we make to the memory image of the file will be written to the file by the system.
 We do not even have to keep the file open: As long as it stays mapped, we can read from it and write to it.
 
 The 32-bit Intel microprocessors can access up to four gigabytes of memory - physical or virtual.
 The FreeBSD system allows us to use up to a half of it for file mapping.
 
 For simplicity sake, in this tutorial we will only convert files that can be mapped into the memory in their entirety.
 There are probably not too many text files that exceed two gigabytes in size.
 If our program encounters one, it will simply display a message suggesting we use the original tuc instead.
 
 If you examine your copy of [.filename]#syscalls.master#, you will find two separate syscalls named `mmap`.
 This is because of evolution of UNIX(R): There was the traditional BSD `mmap`, syscall 71.
 That one was superseded by the POSIX(R) `mmap`, syscall 197.
 The FreeBSD system supports both because older programs were written by using the original BSD version.
 But new software uses the POSIX(R) version, which is what we will use.
 
 The [.filename]#syscalls.master# lists the POSIX(R) version like this:
 
 [.programlisting]
 ....
 197	STD	BSD	{ caddr_t mmap(caddr_t addr, size_t len, int prot, \
 			    int flags, int fd, long pad, off_t pos); }
 ....
 
 This differs slightly from what man:mmap[2] says.
 That is because man:mmap[2] describes the C version.
 
 The difference is in the `long pad` argument, which is not present in the C version.
 However, the FreeBSD syscalls add a 32-bit pad after ``push``ing a 64-bit argument.
 In this case, `off_t` is a 64-bit value.
 
 When we are finished working with a memory-mapped file, we unmap it with the `munmap` syscall:
 
 [TIP]
 ====
 For an in-depth treatment of `mmap`, see W. Richard Stevens' http://www.int80h.org/cgi-bin/isbn?isbn=0130810819[Unix Network Programming, Volume 2, Chapter 12].
 ====
 
 [[x86-file-size]]
 === Determining File Size
 
 Because we need to tell `mmap` how many bytes of the file to map into the memory, and because we want to map the entire file, we need to determine the size of the file.
 
 We can use the `fstat` syscall to get all the information about an open file that the system can give us.
 That includes the file size.
 
 Again, [.filename]#syscalls.master# lists two versions of `fstat`, a traditional one (syscall 62), and a POSIX(R) one (syscall 189).
 Naturally, we will use the POSIX(R) version:
 
 [.programlisting]
 ....
 189	STD	POSIX	{ int fstat(int fd, struct stat *sb); }
 ....
 
 This is a very straightforward call: We pass to it the address of a `stat` structure and the descriptor of an open file.
 It will fill out the contents of the `stat` structure.
 
 I do, however, have to say that I tried to declare the `stat` structure in the `.bss` section, and `fstat` did not like it: It set the carry flag indicating an error.
 After I changed the code to allocate the structure on the stack, everything was working fine.
 
 [[x86-ftruncate]]
 === Changing the File Size
 
 Because our program may combine carriage return / line feed sequences into straight line feeds, our output may be smaller than our input.
 However, since we are placing our output into the same file we read the input from, we may have to change the size of the file.
 
 The `ftruncate` system call allows us to do just that.
 Despite its somewhat misleading name, the `ftruncate` system call can be used to both truncate the file (make it smaller) and to grow it.
 
 And yes, we will find two versions of `ftruncate` in [.filename]#syscalls.master#, an older one (130), and a newer one (201).
 We will use the newer one:
 
 [.programlisting]
 ....
 201	STD	BSD	{ int ftruncate(int fd, int pad, off_t length); }
 ....
 
 Please note that this one contains a `int pad` again.
 
 [[x86-ftuc]]
 === ftuc
 
 We now know everything we need to write ftuc.
 We start by adding some new lines in [.filename]#system.inc#.
 First, we define some constants and structures, somewhere at or near the beginning of the file:
 
 [.programlisting]
 ....
 ;;;;;;; open flags
 %define	O_RDONLY	0
 %define	O_WRONLY	1
 %define	O_RDWR	2
 
 ;;;;;;; mmap flags
 %define	PROT_NONE	0
 %define	PROT_READ	1
 %define	PROT_WRITE	2
 %define	PROT_EXEC	4
 ;;
 %define	MAP_SHARED	0001h
 %define	MAP_PRIVATE	0002h
 
 ;;;;;;; stat structure
 struc	stat
 st_dev		resd	1	; = 0
 st_ino		resd	1	; = 4
 st_mode		resw	1	; = 8, size is 16 bits
 st_nlink	resw	1	; = 10, ditto
 st_uid		resd	1	; = 12
 st_gid		resd	1	; = 16
 st_rdev		resd	1	; = 20
 st_atime	resd	1	; = 24
 st_atimensec	resd	1	; = 28
 st_mtime	resd	1	; = 32
 st_mtimensec	resd	1	; = 36
 st_ctime	resd	1	; = 40
 st_ctimensec	resd	1	; = 44
 st_size		resd	2	; = 48, size is 64 bits
 st_blocks	resd	2	; = 56, ditto
 st_blksize	resd	1	; = 64
 st_flags	resd	1	; = 68
 st_gen		resd	1	; = 72
 st_lspare	resd	1	; = 76
 st_qspare	resd	4	; = 80
 endstruc
 ....
 
 We define the new syscalls:
 
 [.programlisting]
 ....
 %define	SYS_mmap	197
 %define	SYS_munmap	73
 %define	SYS_fstat	189
 %define	SYS_ftruncate	201
 ....
 
 We add the macros for their use:
 
 [.programlisting]
 ....
 %macro	sys.mmap	0
 	system	SYS_mmap
 %endmacro
 
 %macro	sys.munmap	0
 	system	SYS_munmap
 %endmacro
 
 %macro	sys.ftruncate	0
 	system	SYS_ftruncate
 %endmacro
 
 %macro	sys.fstat	0
 	system	SYS_fstat
 %endmacro
 ....
 
 And here is our code:
 
 [.programlisting]
 ....
 ;;;;;;; Fast Text-to-Unix Conversion (ftuc.asm) ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
 ;; Started:	21-Dec-2000
 ;; Updated:	22-Dec-2000
 ;;
 ;; Copyright 2000 G. Adam Stanislav.
 ;; All rights reserved.
 ;;
 ;;;;;;; v.1 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 %include	'system.inc'
 
 section	.data
 	db	'Copyright 2000 G. Adam Stanislav.', 0Ah
 	db	'All rights reserved.', 0Ah
 usg	db	'Usage: ftuc filename', 0Ah
 usglen	equ	$-usg
 co	db	"ftuc: Can't open file.", 0Ah
 colen	equ	$-co
 fae	db	'ftuc: File access error.', 0Ah
 faelen	equ	$-fae
 ftl	db	'ftuc: File too long, use regular tuc instead.', 0Ah
 ftllen	equ	$-ftl
 mae	db	'ftuc: Memory allocation error.', 0Ah
 maelen	equ	$-mae
 
 section	.text
 
 align 4
 memerr:
 	push	dword maelen
 	push	dword mae
 	jmp	short error
 
 align 4
 toolong:
 	push	dword ftllen
 	push	dword ftl
 	jmp	short error
 
 align 4
 facerr:
 	push	dword faelen
 	push	dword fae
 	jmp	short error
 
 align 4
 cantopen:
 	push	dword colen
 	push	dword co
 	jmp	short error
 
 align 4
 usage:
 	push	dword usglen
 	push	dword usg
 
 error:
 	push	dword stderr
 	sys.write
 
 	push	dword 1
 	sys.exit
 
 align 4
 global	_start
 _start:
 	pop	eax		; argc
 	pop	eax		; program name
 	pop	ecx		; file to convert
 	jecxz	usage
 
 	pop	eax
 	or	eax, eax	; Too many arguments?
 	jne	usage
 
 	; Open the file
 	push	dword O_RDWR
 	push	ecx
 	sys.open
 	jc	cantopen
 
 	mov	ebp, eax	; Save fd
 
 	sub	esp, byte stat_size
 	mov	ebx, esp
 
 	; Find file size
 	push	ebx
 	push	ebp		; fd
 	sys.fstat
 	jc	facerr
 
 	mov	edx, [ebx + st_size + 4]
 
 	; File is too long if EDX != 0 ...
 	or	edx, edx
 	jne	near toolong
 	mov	ecx, [ebx + st_size]
 	; ... or if it is above 2 GB
 	or	ecx, ecx
 	js	near toolong
 
 	; Do nothing if the file is 0 bytes in size
 	jecxz	.quit
 
 	; Map the entire file in memory
 	push	edx
 	push	edx		; starting at offset 0
 	push	edx		; pad
 	push	ebp		; fd
 	push	dword MAP_SHARED
 	push	dword PROT_READ | PROT_WRITE
 	push	ecx		; entire file size
 	push	edx		; let system decide on the address
 	sys.mmap
 	jc	near memerr
 
 	mov	edi, eax
 	mov	esi, eax
 	push	ecx		; for SYS_munmap
 	push	edi
 
 	; Use EBX for state machine
 	mov	ebx, ordinary
 	mov	ah, 0Ah
 	cld
 
 .loop:
 	lodsb
 	call	ebx
 	loop	.loop
 
 	cmp	ebx, ordinary
 	je	.filesize
 
 	; Output final lf
 	mov	al, ah
 	stosb
 	inc	edx
 
 .filesize:
 	; truncate file to new size
 	push	dword 0		; high dword
 	push	edx		; low dword
 	push	eax		; pad
 	push	ebp
 	sys.ftruncate
 
 	; close it (ebp still pushed)
 	sys.close
 
 	add	esp, byte 16
 	sys.munmap
 
 .quit:
 	push	dword 0
 	sys.exit
 
 align 4
 ordinary:
 	cmp	al, 0Dh
 	je	.cr
 
 	cmp	al, ah
 	je	.lf
 
 	stosb
 	inc	edx
 	ret
 
 align 4
 .cr:
 	mov	ebx, cr
 	ret
 
 align 4
 .lf:
 	mov	ebx, lf
 	ret
 
 align 4
 cr:
 	cmp	al, 0Dh
 	je	.cr
 
 	cmp	al, ah
 	je	.lf
 
 	xchg	al, ah
 	stosb
 	inc	edx
 
 	xchg	al, ah
 	; fall through
 
 .lf:
 	stosb
 	inc	edx
 	mov	ebx, ordinary
 	ret
 
 align 4
 .cr:
 	mov	al, ah
 	stosb
 	inc	edx
 	ret
 
 align 4
 lf:
 	cmp	al, ah
 	je	.lf
 
 	cmp	al, 0Dh
 	je	.cr
 
 	xchg	al, ah
 	stosb
 	inc	edx
 
 	xchg	al, ah
 	stosb
 	inc	edx
 	mov	ebx, ordinary
 	ret
 
 align 4
 .cr:
 	mov	ebx, ordinary
 	mov	al, ah
 	; fall through
 
 .lf:
 	stosb
 	inc	edx
 	ret
 ....
 
 [WARNING]
 ====
 Do not use this program on files stored on a disk formatted by MS-DOS(R) or Windows(R).
 There seems to be a subtle bug in the FreeBSD code when using `mmap` on these drives mounted under FreeBSD:
 If the file is over a certain size, `mmap` will just fill the memory with zeros, and then copy them to the file overwriting its contents.
 ====
 
 [[x86-one-pointed-mind]]
 == One-Pointed Mind
 
 As a student of Zen, I like the idea of a one-pointed mind: Do one thing at a time, and do it well.
 
 This, indeed, is very much how UNIX(R) works as well.
 While a typical Windows(R) application is attempting to do everything imaginable (and is, therefore, riddled with bugs), a typical UNIX(R) program does only one thing, and it does it well.
 
 The typical UNIX(R) user then essentially assembles his own applications by writing a shell script which combines the various existing programs by piping the output of one program to the input of another.
 
 When writing your own UNIX(R) software, it is generally a good idea to see what parts of the problem you need to solve can be handled by existing programs, and only write your own programs for that part of the problem that you do not have an existing solution for.
 
 [[x86-csv]]
 === CSV
 
 I will illustrate this principle with a specific real-life example I was faced with recently:
 
 I needed to extract the 11th field of each record from a database I downloaded from a web site.
 The database was a CSV file, i.e., a list of _comma-separated values_.
 That is quite a standard format for sharing data among people who may be using different database software.
 
 The first line of the file contains the list of various fields separated by commas.
 The rest of the file contains the data listed line by line, with values separated by commas.
 
 I tried awk, using the comma as a separator. But because several lines contained a quoted comma, awk was extracting the wrong field from those lines.
 
 Therefore, I needed to write my own software to extract the 11th field from the CSV file.
 However, going with the UNIX(R) spirit, I only needed to write a simple filter that would do the following:
 
 * Remove the first line from the file;
 * Change all unquoted commas to a different character;
 * Remove all quotation marks.
 
 Strictly speaking, I could use sed to remove the first line from the file, but doing so in my own program was very easy, so I decided to do it and reduce the size of the pipeline.
 
 At any rate, writing a program like this took me about 20 minutes.
 Writing a program that extracts the 11th field from the CSV file would take a lot longer,
 and I could not reuse it to extract some other field from some other database.
 
 This time I decided to let it do a little more work than a typical tutorial program would:
 
 * It parses its command line for options;
 * It displays proper usage if it finds wrong arguments;
 * It produces meaningful error messages.
 
 Here is its usage message:
 
 [source,shell]
 ....
 Usage: csv [-t<delim>] [-c<comma>] [-p] [-o <outfile>] [-i <infile>]
 ....
 
 All parameters are optional, and can appear in any order.
 
 The `-t` parameter declares what to replace the commas with.
 The `tab` is the default here.
 For example, `-t;` will replace all unquoted commas with semicolons.
 
 I did not need the `-c` option, but it may come in handy in the future.
 It lets me declare that I want a character other than a comma replaced with something else.
 For example, `-c@` will replace all at signs (useful if you want to split a list of email addresses to their user names and domains).
 
 The `-p` option preserves the first line, i.e., it does not delete it.
 By default, we delete the first line because in a CSV file it contains the field names rather than data.
 
 The `-i` and `-o` options let me specify the input and the output files.
 Defaults are [.filename]#stdin# and [.filename]#stdout#, so this is a regular UNIX(R) filter.
 
 I made sure that both `-i filename` and `-ifilename` are accepted.
 I also made sure that only one input and one output files may be specified.
 
 To get the 11th field of each record, I can now do:
 
 [source,shell]
 ....
 % csv '-t;' data.csv | awk '-F;' '{print $11}'
 ....
 
 The code stores the options (except for the file descriptors) in `EDX`: The comma in `DH`, the new separator in `DL`, and the flag for the `-p` option in the highest bit of `EDX`, so a check for its sign will give us a quick decision what to do.
 
 Here is the code:
 
 [.programlisting]
 ....
 ;;;;;;; csv.asm ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;
 ; Convert a comma-separated file to a something-else separated file.
 ;
 ; Started:	31-May-2001
 ; Updated:	 1-Jun-2001
 ;
 ; Copyright (c) 2001 G. Adam Stanislav
 ; All rights reserved.
 ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 %include	'system.inc'
 
 %define	BUFSIZE	2048
 
 section	.data
 fd.in	dd	stdin
 fd.out	dd	stdout
 usg	db	'Usage: csv [-t<delim>] [-c<comma>] [-p] [-o <outfile>] [-i <infile>]', 0Ah
 usglen	equ	$-usg
 iemsg	db	"csv: Can't open input file", 0Ah
 iemlen	equ	$-iemsg
 oemsg	db	"csv: Can't create output file", 0Ah
 oemlen	equ	$-oemsg
 
 section .bss
 ibuffer	resb	BUFSIZE
 obuffer	resb	BUFSIZE
 
 section	.text
 align 4
 ierr:
 	push	dword iemlen
 	push	dword iemsg
 	push	dword stderr
 	sys.write
 	push	dword 1		; return failure
 	sys.exit
 
 align 4
 oerr:
 	push	dword oemlen
 	push	dword oemsg
 	push	dword stderr
 	sys.write
 	push	dword 2
 	sys.exit
 
 align 4
 usage:
 	push	dword usglen
 	push	dword usg
 	push	dword stderr
 	sys.write
 	push	dword 3
 	sys.exit
 
 align 4
 global	_start
 _start:
 	add	esp, byte 8	; discard argc and argv[0]
 	mov	edx, (',' << 8) | 9
 
 .arg:
 	pop	ecx
 	or	ecx, ecx
 	je	near .init		; no more arguments
 
 	; ECX contains the pointer to an argument
 	cmp	byte [ecx], '-'
 	jne	usage
 
 	inc	ecx
 	mov	ax, [ecx]
 
 .o:
 	cmp	al, 'o'
 	jne	.i
 
 	; Make sure we are not asked for the output file twice
 	cmp	dword [fd.out], stdout
 	jne	usage
 
 	; Find the path to output file - it is either at [ECX+1],
 	; i.e., -ofile --
 	; or in the next argument,
 	; i.e., -o file
 
 	inc	ecx
 	or	ah, ah
 	jne	.openoutput
 	pop	ecx
 	jecxz	usage
 
 .openoutput:
 	push	dword 420	; file mode (644 octal)
 	push	dword 0200h | 0400h | 01h
 	; O_CREAT | O_TRUNC | O_WRONLY
 	push	ecx
 	sys.open
 	jc	near oerr
 
 	add	esp, byte 12
 	mov	[fd.out], eax
 	jmp	short .arg
 
 .i:
 	cmp	al, 'i'
 	jne	.p
 
 	; Make sure we are not asked twice
 	cmp	dword [fd.in], stdin
 	jne	near usage
 
 	; Find the path to the input file
 	inc	ecx
 	or	ah, ah
 	jne	.openinput
 	pop	ecx
 	or	ecx, ecx
 	je near usage
 
 .openinput:
 	push	dword 0		; O_RDONLY
 	push	ecx
 	sys.open
 	jc	near ierr		; open failed
 
 	add	esp, byte 8
 	mov	[fd.in], eax
 	jmp	.arg
 
 .p:
 	cmp	al, 'p'
 	jne	.t
 	or	ah, ah
 	jne	near usage
 	or	edx, 1 << 31
 	jmp	.arg
 
 .t:
 	cmp	al, 't'		; redefine output delimiter
 	jne	.c
 	or	ah, ah
 	je	near usage
 	mov	dl, ah
 	jmp	.arg
 
 .c:
 	cmp	al, 'c'
 	jne	near usage
 	or	ah, ah
 	je	near usage
 	mov	dh, ah
 	jmp	.arg
 
 align 4
 .init:
 	sub	eax, eax
 	sub	ebx, ebx
 	sub	ecx, ecx
 	mov	edi, obuffer
 
 	; See if we are to preserve the first line
 	or	edx, edx
 	js	.loop
 
 .firstline:
 	; get rid of the first line
 	call	getchar
 	cmp	al, 0Ah
 	jne	.firstline
 
 .loop:
 	; read a byte from stdin
 	call	getchar
 
 	; is it a comma (or whatever the user asked for)?
 	cmp	al, dh
 	jne	.quote
 
 	; Replace the comma with a tab (or whatever the user wants)
 	mov	al, dl
 
 .put:
 	call	putchar
 	jmp	short .loop
 
 .quote:
 	cmp	al, '"'
 	jne	.put
 
 	; Print everything until you get another quote or EOL. If it
 	; is a quote, skip it. If it is EOL, print it.
 .qloop:
 	call	getchar
 	cmp	al, '"'
 	je	.loop
 
 	cmp	al, 0Ah
 	je	.put
 
 	call	putchar
 	jmp	short .qloop
 
 align 4
 getchar:
 	or	ebx, ebx
 	jne	.fetch
 
 	call	read
 
 .fetch:
 	lodsb
 	dec	ebx
 	ret
 
 read:
 	jecxz	.read
 	call	write
 
 .read:
 	push	dword BUFSIZE
 	mov	esi, ibuffer
 	push	esi
 	push	dword [fd.in]
 	sys.read
 	add	esp, byte 12
 	mov	ebx, eax
 	or	eax, eax
 	je	.done
 	sub	eax, eax
 	ret
 
 align 4
 .done:
 	call	write		; flush output buffer
 
 	; close files
 	push	dword [fd.in]
 	sys.close
 
 	push	dword [fd.out]
 	sys.close
 
 	; return success
 	push	dword 0
 	sys.exit
 
 align 4
 putchar:
 	stosb
 	inc	ecx
 	cmp	ecx, BUFSIZE
 	je	write
 	ret
 
 align 4
 write:
 	jecxz	.ret	; nothing to write
 	sub	edi, ecx	; start of buffer
 	push	ecx
 	push	edi
 	push	dword [fd.out]
 	sys.write
 	add	esp, byte 12
 	sub	eax, eax
 	sub	ecx, ecx	; buffer is empty now
 .ret:
 	ret
 ....
 
 Much of it is taken from [.filename]#hex.asm# above.
 But there is one important difference: I no longer call `write` whenever I am outputting a line feed.
 Yet, the code can be used interactively.
 
 I have found a better solution for the interactive problem since I first started writing this chapter.
 I wanted to make sure each line is printed out separately only when needed.
 After all, there is no need to flush out every line when used non-interactively.
 
 The new solution I use now is to call `write` every time I find the input buffer empty.
 That way, when running in the interactive mode, the program reads one line from the user's keyboard, processes it, and sees its input buffer is empty.
 It flushes its output and reads the next line.
 
 [[x86-buffered-dark-side]]
 ==== The Dark Side of Buffering
 
 This change prevents a mysterious lockup in a very specific case.
 I refer to it as the _dark side of buffering_, mostly because it presents a danger that is not quite obvious.
 
 It is unlikely to happen with a program like the csv above, so let us consider yet another filter:
 In this case we expect our input to be raw data representing color values, such as the _red_, _green_, and _blue_ intensities of a pixel.
 Our output will be the negative of our input.
 
 Such a filter would be very simple to write.
 Most of it would look just like all the other filters we have written so far, so I am only going to show you its inner loop:
 
 [.programlisting]
 ....
 .loop:
 	call	getchar
 	not	al		; Create a negative
 	call	putchar
 	jmp	short .loop
 ....
 
 Because this filter works with raw data, it is unlikely to be used interactively.
 
 But it could be called by image manipulation software.
 And, unless it calls `write` before each call to `read`, chances are it will lock up.
 
 Here is what might happen:
 
 [.procedure]
 . The image editor will load our filter using the C function `popen()`.
 . It will read the first row of pixels from a bitmap or pixmap.
 . It will write the first row of pixels to the _pipe_ leading to the `fd.in` of our filter.
 . Our filter will read each pixel from its input, turn it to a negative, and write it to its output buffer.
 . Our filter will call `getchar` to fetch the next pixel.
 . `getchar` will find an empty input buffer, so it will call `read`.
 . `read` will call the `SYS_read` system call.
 . The _kernel_ will suspend our filter until the image editor sends more data to the pipe.
 . The image editor will read from the other pipe, connected to the `fd.out` of our filter so it can set the first row of the output image _before_ it sends us the second row of the input.
 . The _kernel_ suspends the image editor until it receives some output from our filter, so it can pass it on to the image editor.
 
 At this point our filter waits for the image editor to send it more data to process,
 while the image editor is waiting for our filter to send it the result of the processing of the first row.
 But the result sits in our output buffer.
 
 The filter and the image editor will continue waiting for each other forever (or, at least, until they are killed).
 Our software has just entered a crossref:secure[secure-race-conditions,race condition].
 
 This problem does not exist if our filter flushes its output buffer _before_ asking the _kernel_ for more input data.
 
 [[x86-fpu]]
 == Using the FPU
 
 Strangely enough, most of assembly language literature does not even mention the existence of the FPU, or _floating point unit_, let alone discuss programming it.
 
 Yet, never does assembly language shine more than when we create highly optimized FPU code by doing things that can be done _only_ in assembly language.
 
 [[x86-fpu-organization]]
 === Organization of the FPU
 
 The FPU consists of 8 80-bit floating-point registers.
 These are organized in a stack fashion-you can `push` a value on TOS (_top of stack_) and you can `pop` it.
 
 That said, the assembly language op codes are not `push` and `pop` because those are already taken.
 
 You can `push` a value on TOS by using `fld`, `fild`, and `fbld`.
 Several other op codes let you `push` many common _constants_-such as _pi_-on the TOS.
 
 Similarly, you can `pop` a value by using `fst`, `fstp`, `fist`, `fistp`, and `fbstp`.
 Actually, only the op codes that end with a _p_ will literally `pop` the value, the rest will `store` it somewhere else without removing it from the TOS.
 
 We can transfer the data between the TOS and the computer memory either as a 32-bit, 64-bit, or 80-bit _real_, a 16-bit, 32-bit, or 64-bit _integer_, or an 80-bit _packed decimal_.
 
 The 80-bit _packed decimal_ is a special case of _binary coded decimal_ which is very convenient when converting between the ASCII representation of data and the internal data of the FPU.
 It allows us to use 18 significant digits.
 
 No matter how we represent data in the memory, the FPU always stores it in the 80-bit _real_ format in its registers.
 
 Its internal precision is at least 19 decimal digits, so even if we choose to display results as ASCII in the full 18-digit precision, we are still showing correct results.
 
 We can perform mathematical operations on the TOS: We can calculate its _sine_, we can _scale_ it (i.e., we can multiply or divide it by a power of 2), we can calculate its base-2 _logarithm_, and many other things.
 
 We can also _multiply_ or _divide_ it by, _add_ it to, or _subtract_ it from, any of the FPU registers (including itself).
 
 The official Intel op code for the TOS is `st`, and for the _registers_ `st(0)`-`st(7)`.
 `st` and `st(0)`, then, refer to the same register.
 
 For whatever reasons, the original author of nasm has decided to use different op codes, namely `st0`-`st7`.
 In other words, there are no parentheses, and the TOS is always `st0`, never just `st`.
 
 [[x86-fpu-packed-decimal]]
 ==== The Packed Decimal Format
 
 The _packed decimal_ format uses 10 bytes (80 bits) of memory to represent 18 digits.
 The number represented there is always an _integer_.
 
 [TIP]
 ====
 You can use it to get decimal places by multiplying the TOS by a power of 10 first.
 ====
 
 The highest bit of the highest byte (byte 9) is the _sign bit_: If it is set, the number is _negative_, otherwise, it is _positive_.
 The rest of the bits of this byte are unused/ignored.
 
 The remaining 9 bytes store the 18 digits of the number: 2 digits per byte.
 
 The _more significant digit_ is stored in the high _nibble_ (4 bits), the _less significant digit_ in the low _nibble_.
 
 That said, you might think that `-1234567` would be stored in the memory like this (using hexadecimal notation):
 
 [.programlisting]
 ....
 80 00 00 00 00 00 01 23 45 67
 ....
 
 Alas it is not! As with everything else of Intel make, even the _packed decimal_ is _little-endian_.
 
 That means our `-1234567` is stored like this:
 
 [.programlisting]
 ....
 67 45 23 01 00 00 00 00 00 80
 ....
 
 Remember that, or you will be pulling your hair out in desperation!
 
 [NOTE]
 ====
 The book to read-if you can find it-is Richard Startz' http://www.amazon.com/exec/obidos/ASIN/013246604X/whizkidtechnomag[8087/80287/80387 for the IBM PC & Compatibles].
 Though it does seem to take the fact about the little-endian storage of the _packed decimal_ for granted.
 I kid you not about the desperation of trying to figure out what was wrong with the filter I show below _before_ it occurred to me I should try the little-endian order even for this type of data.
 ====
 
 [[x86-pinhole-photography]]
 === Excursion to Pinhole Photography
 
 To write meaningful software, we must not only understand our programming tools, but also the field we are creating software for.
 
 Our next filter will help us whenever we want to build a _pinhole camera_, so, we need some background in _pinhole photography_ before we can continue.
 
 [[x86-camera]]
 ==== The Camera
 
 The easiest way to describe any camera ever built is as some empty space enclosed in some lightproof material, with a small hole in the enclosure.
 
 The enclosure is usually sturdy (e.g., a box), though sometimes it is flexible (the bellows).
 It is quite dark inside the camera.
 However, the hole lets light rays in through a single point (though in some cases there may be several).
 These light rays form an image, a representation of whatever is outside the camera, in front of the hole.
 
 If some light sensitive material (such as film) is placed inside the camera, it can capture the image.
 
 The hole often contains a _lens_, or a lens assembly, often called the _objective_.
 
 [[x86-the-pinhole]]
 ==== The Pinhole
 
 But, strictly speaking, the lens is not necessary: The original cameras did not use a lens but a _pinhole_.
 Even today, _pinholes_ are used, both as a tool to study how cameras work, and to achieve a special kind of image.
 
 The image produced by the _pinhole_ is all equally sharp.
 Or _blurred_.
 There is an ideal size for a pinhole: If it is either larger or smaller, the image loses its sharpness.
 
 [[x86-focal-length]]
 ==== Focal Length
 
 This ideal pinhole diameter is a function of the square root of _focal length_, which is the distance of the pinhole from the film.
 
 [.programlisting]
 ....
 D = PC * sqrt(FL)
 ....
 
 In here, `D` is the ideal diameter of the pinhole, `FL` is the focal length, and `PC` is a pinhole constant.
 According to Jay Bender, its value is `0.04`, while Kenneth Connors has determined it to be `0.037`.
 Others have proposed other values.
 Plus, this value is for the daylight only: Other types of light will require a different constant, whose value can only be determined by experimentation.
 
 [[x86-f-number]]
 ==== The F-Number
 
 The f-number is a very useful measure of how much light reaches the film.
 A light meter can determine that, for example, to expose a film of specific sensitivity with f5.6 mkay require the exposure to last 1/1000 sec.
 
 It does not matter whether it is a 35-mm camera, or a 6x9cm camera, etc.
 As long as we know the f-number, we can determine the proper exposure.
 
 The f-number is easy to calculate:
 
 [.programlisting]
 ....
 F = FL / D
 ....
 
 In other words, the f-number equals the focal length divided by the diameter of the pinhole.
 It also means a higher f-number either implies a smaller pinhole or a larger focal distance, or both.
 That, in turn, implies, the higher the f-number, the longer the exposure has to be.
 
 Furthermore, while pinhole diameter and focal distance are one-dimensional measurements, both, the film and the pinhole, are two-dimensional.
 That means that if you have measured the exposure at f-number `A` as `t`, then the exposure at f-number `B` is:
 
 [.programlisting]
 ....
 t * (B / A)²
 ....
 
 [[x86-normalized-f-number]]
 ==== Normalized F-Number
 
 While many modern cameras can change the diameter of their pinhole, and thus their f-number, quite smoothly and gradually, such was not always the case.
 
 To allow for different f-numbers, cameras typically contained a metal plate with several holes of different sizes drilled to them.
 
 Their sizes were chosen according to the above formula in such a way that the resultant f-number was one of standard f-numbers used on all cameras everywhere.
 For example, a very old Kodak Duaflex IV camera in my possession has three such holes for f-numbers 8, 11, and 16.
 
 A more recently made camera may offer f-numbers of 2.8, 4, 5.6, 8, 11, 16, 22, and 32 (as well as others).
 These numbers were not chosen arbitrarily: They all are powers of the square root of 2, though they may be rounded somewha.
 
 [[x86-f-stop]]
 ==== The F-Stop
 
 A typical camera is designed in such a way that setting any of the normalized f-numbers changes the feel of the dial.
 It will naturally _stop_ in that position. Because of that, these positions of the dial are called f-stops.
 
 Since the f-numbers at each stop are powers of the square root of 2, moving the dial by 1 stop will double the amount of light required for proper exposure.
 Moving it by 2 stops will quadruple the required exposure.
 Moving the dial by 3 stops will require the increase in exposure 8 times, etc.
 
 [[x86-pinhole-software]]
 === Designing the Pinhole Software
 
 We are now ready to decide what exactly we want our pinhole software to do.
 
 [[xpinhole-processing-input]]
 ==== Processing Program Input
 
 Since its main purpose is to help us design a working pinhole camera, we will use the _focal length_ as the input to the program.
 This is something we can determine without software: Proper focal length is determined by the size of the film and by the need to shoot "regular" pictures, wide angle pictures, or telephoto pictures.
 
 Most of the programs we have written so far worked with individual characters, or bytes, as their input: The hex program converted individual bytes into a hexadecimal number, the csv program either let a character through, or deleted it, or changed it to a different character, etc.
 
 One program, ftuc used the state machine to consider at most two input bytes at a time.
 
 But our pinhole program cannot just work with individual characters, it has to deal with larger syntactic units.
 
 For example, if we want the program to calculate the pinhole diameter (and other values we will discuss later) at the focal lengths of `100 mm`, `150 mm`, and `210 mm`, we may want to enter something like this:
 
 [source,shell]
 ....
  100, 150, 210
 ....
 
 Our program needs to consider more than a single byte of input at a time.
 When it sees the first `1`, it must understand it is seeing the first digit of a decimal number.
 When it sees the `0` and the other `0`, it must know it is seeing more digits of the same number.
 
 When it encounters the first comma, it must know it is no longer receiving the digits of the first number.
 It must be able to convert the digits of the first number into the value of `100`.
 And the digits of the second number into the value of `150`.
 And, of course, the digits of the third number into the numeric value of `210`.
 
 We need to decide what delimiters to accept: Do the input numbers have to be separated by a comma? If so, how do we treat two numbers separated by something else?
 
 Personally, I like to keep it simple. Something either is a number, so I process it.
 Or it is not a number, so I discard it.
 I do not like the computer complaining about me typing in an extra character when it is _obvious_ that it is an extra character.
 Duh!
 
 Plus, it allows me to break up the monotony of computing and type in a query instead of just a number:
 
 [source,shell]
 ....
 What is the best pinhole diameter for the
 	    focal length of 150?
 ....
 
 There is no reason for the computer to spit out a number of complaints:
 
 [source,shell]
 ....
 Syntax error: What
 Syntax error: is
 Syntax error: the
 Syntax error: best
 ....
 
 Et cetera, et cetera, et cetera.
 
 Secondly, I like the `#` character to denote the start of a comment which extends to the end of the line.
 This does not take too much effort to code, and lets me treat input files for my software as executable scripts.
 
 In our case, we also need to decide what units the input should come in: We choose _millimeters_ because that is how most photographers measure the focus length.
 
 Finally, we need to decide whether to allow the use of the decimal point (in which case we must also consider the fact that much of the world uses a decimal _comma_).
 
 In our case allowing for the decimal point/comma would offer a false sense of precision: There is little if any noticeable difference between the focus lengths of `50` and `51`, so allowing the user to input something like `50.5` is not a good idea.
 This is my opinion, mind you, but I am the one writing this program.
 You can make other choices in yours, of course.
 
 [[x86-pinhole-options]]
 ==== Offering Options
 
 The most important thing we need to know when building a pinhole camera is the diameter of the pinhole.
 Since we want to shoot sharp images, we will use the above formula to calculate the pinhole diameter from focal length.
 As experts are offering several different values for the `PC` constant, we will need to have the choice.
 
 It is traditional in UNIX(R) programming to have two main ways of choosing program parameters, plus to have a default for the time the user does not make a choice.
 
 Why have two ways of choosing?
 
 One is to allow a (relatively) _permanent_ choice that applies automatically each time the software is run without us having to tell it over and over what we want it to do.
 
 The permanent choices may be stored in a configuration file, typically found in the user's home directory.
 The file usually has the same name as the application but is started with a dot.
 Often _"rc"_ is added to the file name.
 So, ours could be [.filename]#~/.pinhole# or [.filename]#~/.pinholerc#. (The [.filename]#~/# means current user's home directory.)
 
 The configuration file is used mostly by programs that have many configurable parameters.
 Those that have only one (or a few) often use a different method:
 They expect to find the parameter in an _environment variable_.
 In our case, we might look at an environment variable named `PINHOLE`.
 
 Usually, a program uses one or the other of the above methods.
 Otherwise, if a configuration file said one thing, but an environment variable another, the program might get confused (or just too complicated).
 
 Because we only need to choose _one_ such parameter, we will go with the second method and search the environment for a variable named `PINHOLE`.
 
 The other way allows us to make _ad hoc_ decisions: _"Though I usually want you to use 0.039, this time I want 0.03872."_
 In other words, it allows us to _override_ the permanent choice.
 
 This type of choice is usually done with command line parameters.
 
 Finally, a program _always_ needs a _default_.
 The user may not make any choices.
 Perhaps he does not know what to choose.
 Perhaps he is "just browsing."
 Preferably, the default will be the value most users would choose anyway.
 That way they do not need to choose.
 Or, rather, they can choose the default without an additional effort.
 
 Given this system, the program may find conflicting options, and handle them this way:
 
 [.procedure]
 . If it finds an _ad hoc_ choice (e.g., command line parameter), it should accept that choice. It must ignore any permanent choice and any default.
 . _Otherwise_, if it finds a permanent option (e.g., an environment variable), it should accept it, and ignore the default.
 . _Otherwise_, it should use the default.
 
 We also need to decide what _format_ our `PC` option should have.
 
 At first site, it seems obvious to use the `PINHOLE=0.04` format for the environment variable, and `-p0.04` for the command line.
 
 Allowing that is actually a security risk. The `PC` constant is a very small number.
 Naturally, we will test our software using various small values of `PC`.
 But what will happen if someone runs the program choosing a huge value?
 
 It may crash the program because we have not designed it to handle huge numbers.
 
 Or, we may spend more time on the program so it can handle huge numbers.
 We might do that if we were writing commercial software for computer illiterate audience.
 
 Or, we might say, _"Tough! The user should know better.""_
 
 Or, we just may make it impossible for the user to enter a huge number.
 This is the approach we will take: We will use an _implied 0._ prefix.
 
 In other words, if the user wants `0.04`, we will expect him to type `-p04`, or set `PINHOLE=04` in his environment.
 So, if he says `-p9999999`, we will interpret it as ``0.9999999``-still ridiculous but at least safer.
 
 Secondly, many users will just want to go with either Bender's constant or Connors' constant.
 To make it easier on them, we will interpret `-b` as identical to `-p04`, and `-c` as identical to `-p037`.
 
 [[x86-pinhole-output]]
 ==== The Output
 
 We need to decide what we want our software to send to the output, and in what format.
 
 Since our input allows for an unspecified number of focal length entries, it makes sense to use a traditional database-style output of showing the result of the calculation for each focal length on a separate line, while separating all values on one line by a `tab` character.
 
 Optionally, we should also allow the user to specify the use of the CSV format we have studied earlier.
 In this case, we will print out a line of comma-separated names describing each field of every line, then show our results as before, but substituting a `comma` for the `tab`.
 
 We need a command line option for the CSV format.
 We cannot use `-c` because that already means _use Connors' constant_.
 For some strange reason, many web sites refer to CSV files as _"Excel spreadsheet"_ (though the CSV format predates Excel).
 We will, therefore, use the `-e` switch to inform our software we want the output in the CSV format.
 
 We will start each line of the output with the focal length.
 This may sound repetitious at first, especially in the interactive mode:
 The user types in the focal length, and we are repeating it.
 
 But the user can type several focal lengths on one line.
 The input can also come in from a file or from the output of another program.
 In that case the user does not see the input at all.
 
 By the same token, the output can go to a file which we will want to examine later, or it could go to the printer, or become the input of another program.
 
 So, it makes perfect sense to start each line with the focal length as entered by the user.
 
 No, wait! Not as entered by the user.
 What if the user types in something like this:
 
 [source,shell]
 ....
  00000000150
 ....
 
 Clearly, we need to strip those leading zeros.
 
 So, we might consider reading the user input as is, converting it to binary inside the FPU, and printing it out from there.
 
 But...
 
 What if the user types something like this:
 
 [source,shell]
 ....
  17459765723452353453534535353530530534563507309676764423
 ....
 
 Ha! The packed decimal FPU format lets us input 18-digit numbers.
 But the user has entered more than 18 digits.
 How do we handle that?
 
 Well, we _could_ modify our code to read the first 18 digits, enter it to the FPU, then read more, multiply what we already have on the TOS by 10 raised to the number of additional digits, then `add` to it.
 
 Yes, we could do that.
 But in _this_ program it would be ridiculous (in a different one it may be just the thing to do): Even the circumference of the Earth expressed in millimeters only takes 11 digits.
 Clearly, we cannot build a camera that large (not yet, anyway).
 
 So, if the user enters such a huge number, he is either bored, or testing us, or trying to break into the system, or playing games-doing anything but designing a pinhole camera.
 
 What will we do?
 
 We will slap him in the face, in a manner of speaking:
 
 [source,shell]
 ....
 17459765723452353453534535353530530534563507309676764423	???	???	???	???	???
 ....
 
 To achieve that, we will simply ignore any leading zeros.
 Once we find a non-zero digit, we will initialize a counter to `0` and start taking three steps:
 
 [.procedure]
 . Send the digit to the output.
 . Append the digit to a buffer we will use later to produce the packed decimal we can send to the FPU.
 . Increase the counter.
 
 Now, while we are taking these three steps, we also need to watch out for one of two conditions:
 
 * If the counter grows above 18, we stop appending to the buffer. We continue reading the digits and sending them to the output.
 * If, or rather _when_, the next input character is not a digit, we are done inputting for now.
-+ 
++
 Incidentally, we can simply discard the non-digit, unless it is a `#`, which we must return to the input stream.
 It starts a comment, so we must see it after we are done producing output and start looking for more input.
 
 That still leaves one possibility uncovered: If all the user enters is a zero (or several zeros), we will never find a non-zero to display.
 
 We can determine this has happened whenever our counter stays at `0`.
 In that case we need to send `0` to the output, and perform another "slap in the face":
 
 [source,shell]
 ....
 0	???	???	???	???	???
 ....
 
 Once we have displayed the focal length and determined it is valid (greater than `0` but not exceeding 18 digits), we can calculate the pinhole diameter.
 
 It is not by coincidence that _pinhole_ contains the word _pin_.
 Indeed, many a pinhole literally is a _pin hole_, a hole carefully punched with the tip of a pin.
 
 That is because a typical pinhole is very small. Our formula gets the result in millimeters.
 We will multiply it by `1000`, so we can output the result in _microns_.
 
 At this point we have yet another trap to face: _Too much precision._
 
 Yes, the FPU was designed for high precision mathematics.
 But we are not dealing with high precision mathematics.
 We are dealing with physics (optics, specifically).
 
 Suppose we want to convert a truck into a pinhole camera (we would not be the first ones to do that!).
 Suppose its box is `12` meters long, so we have the focal length of `12000`.
 Well, using Bender's constant, it gives us square root of `12000` multiplied by `0.04`, which is `4.381780460` millimeters, or `4381.780460` microns.
 
 Put either way, the result is absurdly precise.
 Our truck is not _exactly_ `12000` millimeters long.
 We did not measure its length with such a precision, so stating we need a pinhole with the diameter of `4.381780460` millimeters is, well, deceiving.
 `4.4` millimeters would do just fine.
 
 [NOTE]
 ====
 I "only" used ten digits in the above example.
 Imagine the absurdity of going for all 18!
 ====
 
 We need to limit the number of significant digits of our result.
 One way of doing it is by using an integer representing microns.
 So, our truck would need a pinhole with the diameter of `4382` microns.
 Looking at that number, we still decide that `4400` microns, or `4.4` millimeters is close enough.
 
 Additionally, we can decide that no matter how big a result we get, we only want to display four significant digits (or any other number of them, of course).
 Alas, the FPU does not offer rounding to a specific number of digits (after all, it does not view the numbers as decimal but as binary).
 
 We, therefore, must devise an algorithm to reduce the number of significant digits.
 
 Here is mine (I think it is awkward-if you know a better one, _please_, let me know):
 
 [.procedure]
 . Initialize a counter to `0`.
 . While the number is greater than or equal to `10000`, divide it by `10` and increase the counter.
 . Output the result.
 . While the counter is greater than `0`, output `0` and decrease the counter.
 
 [NOTE]
 ====
 The `10000` is only good if you want _four_ significant digits.
 For any other number of significant digits, replace `10000` with `10` raised to the number of significant digits.
 ====
 
 We will, then, output the pinhole diameter in microns, rounded off to four significant digits.
 
 At this point, we know the _focal length_ and the _pinhole diameter_.
 That means we have enough information to also calculate the _f-number_.
 
 We will display the f-number, rounded to four significant digits.
 Chances are the f-number will tell us very little.
 To make it more meaningful, we can find the nearest _normalized f-number_, i.e., the nearest power of the square root of 2.
 
 We do that by multiplying the actual f-number by itself, which, of course, will give us its `square`.
 We will then calculate its base-2 logarithm, which is much easier to do than calculating the base-square-root-of-2 logarithm! We will round the result to the nearest integer.
 Next, we will raise 2 to the result.
 Actually, the FPU gives us a good shortcut to do that: We can use the `fscale` op code to "scale" 1, which is analogous to ``shift``ing an integer left.
 Finally, we calculate the square root of it all, and we have the nearest normalized f-number.
 
 If all that sounds overwhelming-or too much work, perhaps-it may become much clearer if you see the code.
 It takes 9 op codes altogether:
 
 [.programlisting]
 ....
 fmul	st0, st0
 	fld1
 	fld	st1
 	fyl2x
 	frndint
 	fld1
 	fscale
 	fsqrt
 	fstp	st1
 ....
 
 The first line, `fmul st0, st0`, squares the contents of the TOS (top of the stack, same as `st`, called `st0` by nasm).
 The `fld1` pushes `1` on the TOS.
 
 The next line, `fld st1`, pushes the square back to the TOS.
 At this point the square is both in `st` and `st(2)` (it will become clear why we leave a second copy on the stack in a moment).
 `st(1)` contains `1`.
 
 Next, `fyl2x` calculates base-2 logarithm of `st` multiplied by `st(1)`.
 That is why we placed `1` on `st(1)` before.
 
 At this point, `st` contains the logarithm we have just calculated, `st(1)` contains the square of the actual f-number we saved for later.
 
 `frndint` rounds the TOS to the nearest integer.
 `fld1` pushes a `1`.
 `fscale` shifts the `1` we have on the TOS by the value in `st(1)`, effectively raising 2 to `st(1)`.
 
 Finally, `fsqrt` calculates the square root of the result, i.e., the nearest normalized f-number.
 
 We now have the nearest normalized f-number on the TOS, the base-2 logarithm rounded to the nearest integer in `st(1)`, and the square of the actual f-number in `st(2)`.
 We are saving the value in `st(2)` for later.
 
 But we do not need the contents of `st(1)` anymore.
 The last line, `fstp st1`, places the contents of `st` to `st(1)`, and pops.
 As a result, what was `st(1)` is now `st`, what was `st(2)` is now `st(1)`, etc.
 The new `st` contains the normalized f-number.
 The new `st(1)` contains the square of the actual f-number we have stored there for posterity.
 
 At this point, we are ready to output the normalized f-number.
 Because it is normalized, we will not round it off to four significant digits, but will send it out in its full precision.
 
 The normalized f-number is useful as long as it is reasonably small and can be found on our light meter.
 Otherwise we need a different method of determining proper exposure.
 
 Earlier we have figured out the formula of calculating proper exposure at an arbitrary f-number from that measured at a different f-number.
 
 Every light meter I have ever seen can determine proper exposure at f5.6.
 We will, therefore, calculate an _"f5.6 multiplier,"_ i.e., by how much we need to multiply the exposure measured at f5.6 to determine the proper exposure for our pinhole camera.
 
 From the above formula we know this factor can be calculated by dividing our f-number (the actual one, not the normalized one) by `5.6`, and squaring the result.
 
 Mathematically, dividing the square of our f-number by the square of `5.6` will give us the same result.
 
 Computationally, we do not want to square two numbers when we can only square one.
 So, the first solution seems better at first.
 
 But...
 
 `5.6` is a _constant_.
 We do not have to have our FPU waste precious cycles.
 We can just tell it to divide the square of the f-number by whatever `5.6²` equals to.
 Or we can divide the f-number by `5.6`, and then square the result.
 The two ways now seem equal.
 
 But, they are not!
 
 Having studied the principles of photography above, we remember that the `5.6` is actually square root of 2 raised to the fifth power.
 An _irrational_ number.
 The square of this number is _exactly_ `32`.
 
 Not only is `32` an integer, it is a power of 2.
 We do not need to divide the square of the f-number by `32`.
 We only need to use `fscale` to shift it right by five positions.
 In the FPU lingo it means we will `fscale` it with `st(1)` equal to `-5`.
 That is _much faster_ than a division.
 
 So, now it has become clear why we have saved the square of the f-number on the top of the FPU stack.
 The calculation of the f5.6 multiplier is the easiest calculation of this entire program! We will output it rounded to four significant digits.
 
 There is one more useful number we can calculate: The number of stops our f-number is from f5.6.
 This may help us if our f-number is just outside the range of our light meter, but we have a shutter which lets us set various speeds, and this shutter uses stops.
 
 Say, our f-number is 5 stops from f5.6, and the light meter says we should use 1/1000 sec.
 Then we can set our shutter speed to 1/1000 first, then move the dial by 5 stops.
 
 This calculation is quite easy as well.
 All we have to do is to calculate the base-2 logarithm of the f5.6 multiplier we had just calculated (though we need its value from before we rounded it off).
 We then output the result rounded to the nearest integer.
 We do not need to worry about having more than four significant digits in this one: The result is most likely to have only one or two digits anyway.
 
 [[x86-fpu-optimizations]]
 === FPU Optimizations
 
 In assembly language we can optimize the FPU code in ways impossible in high languages, including C.
 
 Whenever a C function needs to calculate a floating-point value, it loads all necessary variables and constants into FPU registers.
 It then does whatever calculation is required to get the correct result.
 Good C compilers can optimize that part of the code really well.
 
 It "returns" the value by leaving the result on the TOS.
 However, before it returns, it cleans up.
 Any variables and constants it used in its calculation are now gone from the FPU.
 
 It cannot do what we just did above: We calculated the square of the f-number and kept it on the stack for later use by another function.
 
 We _knew_ we would need that value later on.
 We also knew we had enough room on the stack (which only has room for 8 numbers) to store it there.
 
 A C compiler has no way of knowing that a value it has on the stack will be required again in the very near future.
 
 Of course, the C programmer may know it.
 But the only recourse he has is to store the value in a memory variable.
 
 That means, for one, the value will be changed from the 80-bit precision used internally by the FPU to a C _double_ (64 bits) or even _single_ (32 bits).
 
 That also means that the value must be moved from the TOS into the memory, and then back again.
 Alas, of all FPU operations, the ones that access the computer memory are the slowest.
 
 So, whenever programming the FPU in assembly language, look for the ways of keeping intermediate results on the FPU stack.
 
 We can take that idea even further! In our program we are using a _constant_ (the one we named `PC`).
 
 It does not matter how many pinhole diameters we are calculating: 1, 10, 20, 1000, we are always using the same constant.
 Therefore, we can optimize our program by keeping the constant on the stack all the time.
 
 Early on in our program, we are calculating the value of the above constant.
 We need to divide our input by `10` for every digit in the constant.
 
 It is much faster to multiply than to divide.
 So, at the start of our program, we divide `10` into `1` to obtain `0.1`, which we then keep on the stack: Instead of dividing the input by `10` for every digit, we multiply it by `0.1`.
 
 By the way, we do not input `0.1` directly, even though we could.
 We have a reason for that: While `0.1` can be expressed with just one decimal place, we do not know how many _binary_ places it takes.
 We, therefore, let the FPU calculate its binary value to its own high precision.
 
 We are using other constants: We multiply the pinhole diameter by `1000` to convert it from millimeters to microns.
 We compare numbers to `10000` when we are rounding them off to four significant digits.
 So, we keep both, `1000` and `10000`, on the stack.
 And, of course, we reuse the `0.1` when rounding off numbers to four digits.
 
 Last but not least, we keep `-5` on the stack.
 We need it to scale the square of the f-number, instead of dividing it by `32`.
 It is not by coincidence we load this constant last.
 That makes it the top of the stack when only the constants are on it.
 So, when the square of the f-number is being scaled, the `-5` is at `st(1)`, precisely where `fscale` expects it to be.
 
 It is common to create certain constants from scratch instead of loading them from the memory.
 That is what we are doing with `-5`:
 
 [.programlisting]
 ....
 	fld1			; TOS =  1
 	fadd	st0, st0	; TOS =  2
 	fadd	st0, st0	; TOS =  4
 	fld1			; TOS =  1
 	faddp	st1, st0	; TOS =  5
 	fchs			; TOS = -5
 ....
 
 We can generalize all these optimizations into one rule: _Keep repeat values on the stack!_
 
 [TIP]
 ====
 _PostScript(R)_ is a stack-oriented programming language.
 There are many more books available about PostScript(R) than about the FPU assembly language: Mastering PostScript(R) will help you master the FPU.
 ====
 
 [[x86-pinhole-the-code]]
 === pinhole-The Code
 
 [.programlisting]
 ....
 ;;;;;;; pinhole.asm ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;
 ; Find various parameters of a pinhole camera construction and use
 ;
 ; Started:	 9-Jun-2001
 ; Updated:	10-Jun-2001
 ;
 ; Copyright (c) 2001 G. Adam Stanislav
 ; All rights reserved.
 ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 %include	'system.inc'
 
 %define	BUFSIZE	2048
 
 section	.data
 align 4
 ten	dd	10
 thousand	dd	1000
 tthou	dd	10000
 fd.in	dd	stdin
 fd.out	dd	stdout
 envar	db	'PINHOLE='	; Exactly 8 bytes, or 2 dwords long
 pinhole	db	'04,', 		; Bender's constant (0.04)
 connors	db	'037', 0Ah	; Connors' constant
 usg	db	'Usage: pinhole [-b] [-c] [-e] [-p <value>] [-o <outfile>] [-i <infile>]', 0Ah
 usglen	equ	$-usg
 iemsg	db	"pinhole: Can't open input file", 0Ah
 iemlen	equ	$-iemsg
 oemsg	db	"pinhole: Can't create output file", 0Ah
 oemlen	equ	$-oemsg
 pinmsg	db	"pinhole: The PINHOLE constant must not be 0", 0Ah
 pinlen	equ	$-pinmsg
 toobig	db	"pinhole: The PINHOLE constant may not exceed 18 decimal places", 0Ah
 biglen	equ	$-toobig
 huhmsg	db	9, '???'
 separ	db	9, '???'
 sep2	db	9, '???'
 sep3	db	9, '???'
 sep4	db	9, '???', 0Ah
 huhlen	equ	$-huhmsg
 header	db	'focal length in millimeters,pinhole diameter in microns,'
 	db	'F-number,normalized F-number,F-5.6 multiplier,stops '
 	db	'from F-5.6', 0Ah
 headlen	equ	$-header
 
 section .bss
 ibuffer	resb	BUFSIZE
 obuffer	resb	BUFSIZE
 dbuffer	resb	20		; decimal input buffer
 bbuffer	resb	10		; BCD buffer
 
 section	.text
 align 4
 huh:
 	call	write
 	push	dword huhlen
 	push	dword huhmsg
 	push	dword [fd.out]
 	sys.write
 	add	esp, byte 12
 	ret
 
 align 4
 perr:
 	push	dword pinlen
 	push	dword pinmsg
 	push	dword stderr
 	sys.write
 	push	dword 4		; return failure
 	sys.exit
 
 align 4
 consttoobig:
 	push	dword biglen
 	push	dword toobig
 	push	dword stderr
 	sys.write
 	push	dword 5		; return failure
 	sys.exit
 
 align 4
 ierr:
 	push	dword iemlen
 	push	dword iemsg
 	push	dword stderr
 	sys.write
 	push	dword 1		; return failure
 	sys.exit
 
 align 4
 oerr:
 	push	dword oemlen
 	push	dword oemsg
 	push	dword stderr
 	sys.write
 	push	dword 2
 	sys.exit
 
 align 4
 usage:
 	push	dword usglen
 	push	dword usg
 	push	dword stderr
 	sys.write
 	push	dword 3
 	sys.exit
 
 align 4
 global	_start
 _start:
 	add	esp, byte 8	; discard argc and argv[0]
 	sub	esi, esi
 
 .arg:
 	pop	ecx
 	or	ecx, ecx
 	je	near .getenv		; no more arguments
 
 	; ECX contains the pointer to an argument
 	cmp	byte [ecx], '-'
 	jne	usage
 
 	inc	ecx
 	mov	ax, [ecx]
 	inc	ecx
 
 .o:
 	cmp	al, 'o'
 	jne	.i
 
 	; Make sure we are not asked for the output file twice
 	cmp	dword [fd.out], stdout
 	jne	usage
 
 	; Find the path to output file - it is either at [ECX+1],
 	; i.e., -ofile --
 	; or in the next argument,
 	; i.e., -o file
 
 	or	ah, ah
 	jne	.openoutput
 	pop	ecx
 	jecxz	usage
 
 .openoutput:
 	push	dword 420	; file mode (644 octal)
 	push	dword 0200h | 0400h | 01h
 	; O_CREAT | O_TRUNC | O_WRONLY
 	push	ecx
 	sys.open
 	jc	near oerr
 
 	add	esp, byte 12
 	mov	[fd.out], eax
 	jmp	short .arg
 
 .i:
 	cmp	al, 'i'
 	jne	.p
 
 	; Make sure we are not asked twice
 	cmp	dword [fd.in], stdin
 	jne	near usage
 
 	; Find the path to the input file
 	or	ah, ah
 	jne	.openinput
 	pop	ecx
 	or	ecx, ecx
 	je near usage
 
 .openinput:
 	push	dword 0		; O_RDONLY
 	push	ecx
 	sys.open
 	jc	near ierr		; open failed
 
 	add	esp, byte 8
 	mov	[fd.in], eax
 	jmp	.arg
 
 .p:
 	cmp	al, 'p'
 	jne	.c
 	or	ah, ah
 	jne	.pcheck
 
 	pop	ecx
 	or	ecx, ecx
 	je	near usage
 
 	mov	ah, [ecx]
 
 .pcheck:
 	cmp	ah, '0'
 	jl	near usage
 	cmp	ah, '9'
 	ja	near usage
 	mov	esi, ecx
 	jmp	.arg
 
 .c:
 	cmp	al, 'c'
 	jne	.b
 	or	ah, ah
 	jne	near usage
 	mov	esi, connors
 	jmp	.arg
 
 .b:
 	cmp	al, 'b'
 	jne	.e
 	or	ah, ah
 	jne	near usage
 	mov	esi, pinhole
 	jmp	.arg
 
 .e:
 	cmp	al, 'e'
 	jne	near usage
 	or	ah, ah
 	jne	near usage
 	mov	al, ','
 	mov	[huhmsg], al
 	mov	[separ], al
 	mov	[sep2], al
 	mov	[sep3], al
 	mov	[sep4], al
 	jmp	.arg
 
 align 4
 .getenv:
 	; If ESI = 0, we did not have a -p argument,
 	; and need to check the environment for "PINHOLE="
 	or	esi, esi
 	jne	.init
 
 	sub	ecx, ecx
 
 .nextenv:
 	pop	esi
 	or	esi, esi
 	je	.default	; no PINHOLE envar found
 
 	; check if this envar starts with 'PINHOLE='
 	mov	edi, envar
 	mov	cl, 2		; 'PINHOLE=' is 2 dwords long
 rep	cmpsd
 	jne	.nextenv
 
 	; Check if it is followed by a digit
 	mov	al, [esi]
 	cmp	al, '0'
 	jl	.default
 	cmp	al, '9'
 	jbe	.init
 	; fall through
 
 align 4
 .default:
 	; We got here because we had no -p argument,
 	; and did not find the PINHOLE envar.
 	mov	esi, pinhole
 	; fall through
 
 align 4
 .init:
 	sub	eax, eax
 	sub	ebx, ebx
 	sub	ecx, ecx
 	sub	edx, edx
 	mov	edi, dbuffer+1
 	mov	byte [dbuffer], '0'
 
 	; Convert the pinhole constant to real
 .constloop:
 	lodsb
 	cmp	al, '9'
 	ja	.setconst
 	cmp	al, '0'
 	je	.processconst
 	jb	.setconst
 
 	inc	dl
 
 .processconst:
 	inc	cl
 	cmp	cl, 18
 	ja	near consttoobig
 	stosb
 	jmp	short .constloop
 
 align 4
 .setconst:
 	or	dl, dl
 	je	near perr
 
 	finit
 	fild	dword [tthou]
 
 	fld1
 	fild	dword [ten]
 	fdivp	st1, st0
 
 	fild	dword [thousand]
 	mov	edi, obuffer
 
 	mov	ebp, ecx
 	call	bcdload
 
 .constdiv:
 	fmul	st0, st2
 	loop	.constdiv
 
 	fld1
 	fadd	st0, st0
 	fadd	st0, st0
 	fld1
 	faddp	st1, st0
 	fchs
 
 	; If we are creating a CSV file,
 	; print header
 	cmp	byte [separ], ','
 	jne	.bigloop
 
 	push	dword headlen
 	push	dword header
 	push	dword [fd.out]
 	sys.write
 
 .bigloop:
 	call	getchar
 	jc	near done
 
 	; Skip to the end of the line if you got '#'
 	cmp	al, '#'
 	jne	.num
 	call	skiptoeol
 	jmp	short .bigloop
 
 .num:
 	; See if you got a number
 	cmp	al, '0'
 	jl	.bigloop
 	cmp	al, '9'
 	ja	.bigloop
 
 	; Yes, we have a number
 	sub	ebp, ebp
 	sub	edx, edx
 
 .number:
 	cmp	al, '0'
 	je	.number0
 	mov	dl, 1
 
 .number0:
 	or	dl, dl		; Skip leading 0's
 	je	.nextnumber
 	push	eax
 	call	putchar
 	pop	eax
 	inc	ebp
 	cmp	ebp, 19
 	jae	.nextnumber
 	mov	[dbuffer+ebp], al
 
 .nextnumber:
 	call	getchar
 	jc	.work
 	cmp	al, '#'
 	je	.ungetc
 	cmp	al, '0'
 	jl	.work
 	cmp	al, '9'
 	ja	.work
 	jmp	short .number
 
 .ungetc:
 	dec	esi
 	inc	ebx
 
 .work:
 	; Now, do all the work
 	or	dl, dl
 	je	near .work0
 
 	cmp	ebp, 19
 	jae	near .toobig
 
 	call	bcdload
 
 	; Calculate pinhole diameter
 
 	fld	st0	; save it
 	fsqrt
 	fmul	st0, st3
 	fld	st0
 	fmul	st5
 	sub	ebp, ebp
 
 	; Round off to 4 significant digits
 .diameter:
 	fcom	st0, st7
 	fstsw	ax
 	sahf
 	jb	.printdiameter
 	fmul	st0, st6
 	inc	ebp
 	jmp	short .diameter
 
 .printdiameter:
 	call	printnumber	; pinhole diameter
 
 	; Calculate F-number
 
 	fdivp	st1, st0
 	fld	st0
 
 	sub	ebp, ebp
 
 .fnumber:
 	fcom	st0, st6
 	fstsw	ax
 	sahf
 	jb	.printfnumber
 	fmul	st0, st5
 	inc	ebp
 	jmp	short .fnumber
 
 .printfnumber:
 	call	printnumber	; F number
 
 	; Calculate normalized F-number
 	fmul	st0, st0
 	fld1
 	fld	st1
 	fyl2x
 	frndint
 	fld1
 	fscale
 	fsqrt
 	fstp	st1
 
 	sub	ebp, ebp
 	call	printnumber
 
 	; Calculate time multiplier from F-5.6
 
 	fscale
 	fld	st0
 
 	; Round off to 4 significant digits
 .fmul:
 	fcom	st0, st6
 	fstsw	ax
 	sahf
 
 	jb	.printfmul
 	inc	ebp
 	fmul	st0, st5
 	jmp	short .fmul
 
 .printfmul:
 	call	printnumber	; F multiplier
 
 	; Calculate F-stops from 5.6
 
 	fld1
 	fxch	st1
 	fyl2x
 
 	sub	ebp, ebp
 	call	printnumber
 
 	mov	al, 0Ah
 	call	putchar
 	jmp	.bigloop
 
 .work0:
 	mov	al, '0'
 	call	putchar
 
 align 4
 .toobig:
 	call	huh
 	jmp	.bigloop
 
 align 4
 done:
 	call	write		; flush output buffer
 
 	; close files
 	push	dword [fd.in]
 	sys.close
 
 	push	dword [fd.out]
 	sys.close
 
 	finit
 
 	; return success
 	push	dword 0
 	sys.exit
 
 align 4
 skiptoeol:
 	; Keep reading until you come to cr, lf, or eof
 	call	getchar
 	jc	done
 	cmp	al, 0Ah
 	jne	.cr
 	ret
 
 .cr:
 	cmp	al, 0Dh
 	jne	skiptoeol
 	ret
 
 align 4
 getchar:
 	or	ebx, ebx
 	jne	.fetch
 
 	call	read
 
 .fetch:
 	lodsb
 	dec	ebx
 	clc
 	ret
 
 read:
 	jecxz	.read
 	call	write
 
 .read:
 	push	dword BUFSIZE
 	mov	esi, ibuffer
 	push	esi
 	push	dword [fd.in]
 	sys.read
 	add	esp, byte 12
 	mov	ebx, eax
 	or	eax, eax
 	je	.empty
 	sub	eax, eax
 	ret
 
 align 4
 .empty:
 	add	esp, byte 4
 	stc
 	ret
 
 align 4
 putchar:
 	stosb
 	inc	ecx
 	cmp	ecx, BUFSIZE
 	je	write
 	ret
 
 align 4
 write:
 	jecxz	.ret	; nothing to write
 	sub	edi, ecx	; start of buffer
 	push	ecx
 	push	edi
 	push	dword [fd.out]
 	sys.write
 	add	esp, byte 12
 	sub	eax, eax
 	sub	ecx, ecx	; buffer is empty now
 .ret:
 	ret
 
 align 4
 bcdload:
 	; EBP contains the number of chars in dbuffer
 	push	ecx
 	push	esi
 	push	edi
 
 	lea	ecx, [ebp+1]
 	lea	esi, [dbuffer+ebp-1]
 	shr	ecx, 1
 
 	std
 
 	mov	edi, bbuffer
 	sub	eax, eax
 	mov	[edi], eax
 	mov	[edi+4], eax
 	mov	[edi+2], ax
 
 .loop:
 	lodsw
 	sub	ax, 3030h
 	shl	al, 4
 	or	al, ah
 	mov	[edi], al
 	inc	edi
 	loop	.loop
 
 	fbld	[bbuffer]
 
 	cld
 	pop	edi
 	pop	esi
 	pop	ecx
 	sub	eax, eax
 	ret
 
 align 4
 printnumber:
 	push	ebp
 	mov	al, [separ]
 	call	putchar
 
 	; Print the integer at the TOS
 	mov	ebp, bbuffer+9
 	fbstp	[bbuffer]
 
 	; Check the sign
 	mov	al, [ebp]
 	dec	ebp
 	or	al, al
 	jns	.leading
 
 	; We got a negative number (should never happen)
 	mov	al, '-'
 	call	putchar
 
 .leading:
 	; Skip leading zeros
 	mov	al, [ebp]
 	dec	ebp
 	or	al, al
 	jne	.first
 	cmp	ebp, bbuffer
 	jae	.leading
 
 	; We are here because the result was 0.
 	; Print '0' and return
 	mov	al, '0'
 	jmp	putchar
 
 .first:
 	; We have found the first non-zero.
 	; But it is still packed
 	test	al, 0F0h
 	jz	.second
 	push	eax
 	shr	al, 4
 	add	al, '0'
 	call	putchar
 	pop	eax
 	and	al, 0Fh
 
 .second:
 	add	al, '0'
 	call	putchar
 
 .next:
 	cmp	ebp, bbuffer
 	jb	.done
 
 	mov	al, [ebp]
 	push	eax
 	shr	al, 4
 	add	al, '0'
 	call	putchar
 	pop	eax
 	and	al, 0Fh
 	add	al, '0'
 	call	putchar
 
 	dec	ebp
 	jmp	short .next
 
 .done:
 	pop	ebp
 	or	ebp, ebp
 	je	.ret
 
 .zeros:
 	mov	al, '0'
 	call	putchar
 	dec	ebp
 	jne	.zeros
 
 .ret:
 	ret
 ....
 
 The code follows the same format as all the other filters we have seen before, with one subtle exception:
 
 ____
 We are no longer assuming that the end of input implies the end of things to do, something we took for granted in the _character-oriented_ filters.
 
 This filter does not process characters. It processes a _language_ (albeit a very simple one, consisting only of numbers).
 
 When we have no more input, it can mean one of two things:
 
 * We are done and can quit. This is the same as before.
 * The last character we have read was a digit. We have stored it at the end of our ASCII-to-float conversion buffer. We now need to convert the contents of that buffer into a number and write the last line of our output.
 
 For that reason, we have modified our `getchar` and our `read` routines to return with the `carry flag` _clear_ whenever we are fetching another character from the input, or the `carry flag` _set_ whenever there is no more input.
 
 Of course, we are still using assembly language magic to do that! Take a good look at `getchar`.
 It _always_ returns with the `carry flag` _clear_.
 
 Yet, our main code relies on the `carry flag` to tell it when to quit-and it works.
 
 The magic is in `read`.
 Whenever it receives more input from the system, it just returns to `getchar`, which fetches a character from the input buffer, _clears_ the `carry flag` and returns.
 
 But when `read` receives no more input from the system, it does _not_ return to `getchar` at all.
 Instead, the `add esp, byte 4` op code adds `4` to `ESP`, _sets_ the `carry flag`, and returns.
 
 So, where does it return to? Whenever a program uses the `call` op code, the microprocessor ``push``es the return address, i.e.,
 it stores it on the top of the stack (not the FPU stack, the system stack, which is in the memory).
 When a program uses the `ret` op code, the microprocessor ``pop``s the return value from the stack, and jumps to the address that was stored there.
 
 But since we added `4` to `ESP` (which is the stack pointer register), we have effectively given the microprocessor a minor case of _amnesia_: It no longer remembers it was `getchar` that ``call``ed `read`.
 
 And since `getchar` never ``push``ed anything before ``call``ing `read`, the top of the stack now contains the return address to whatever or whoever ``call``ed `getchar`. As far as that caller is concerned, he ``call``ed `getchar`, which ``ret``urned with the `carry flag` set!
 ____
 
 Other than that, the `bcdload` routine is caught up in the middle of a Lilliputian conflict between the Big-Endians and the Little-Endians.
 
 It is converting the text representation of a number into that number: The text is stored in the big-endian order, but the _packed decimal_ is little-endian.
 
 To solve the conflict, we use the `std` op code early on.
 We cancel it with `cld` later on: It is quite important we do not `call` anything that may depend on the default setting of the _direction flag_ while `std` is active.
 
 Everything else in this code should be quit eclear, providing you have read the entire chapter that precedes it.
 
 It is a classical example of the adage that programming requires a lot of thought and only a little coding.
 Once we have thought through every tiny detail, the code almost writes itself.
 
 [[x86-pinhole-using]]
 === Using pinhole
 
 Because we have decided to make the program _ignore_ any input except for numbers (and even those inside a comment), we can actually perform _textual queries_.
 We do not _have to_, but we _can_.
 
 In my humble opinion, forming a textual query, instead of having to follow a very strict syntax, makes software much more user friendly.
 
 Suppose we want to build a pinhole camera to use the 4x5 inch film.
 The standard focal length for that film is about 150mm.
 We want to _fine-tune_ our focal length so the pinhole diameter is as round a number as possible.
 Let us also suppose we are quite comfortable with cameras but somewhat intimidated by computers.
 Rather than just have to type in a bunch of numbers, we want to _ask_ a couple of questions.
 
 Our session might look like this:
 
 [source,shell]
 ....
 % pinhole
 
 Computer,
 
 What size pinhole do I need for the focal length of 150?
 150	490	306	362	2930	12
 Hmmm... How about 160?
 160	506	316	362	3125	12
 Let's make it 155, please.
 155	498	311	362	3027	12
 Ah, let's try 157...
 157	501	313	362	3066	12
 156?
 156	500	312	362	3047	12
 That's it! Perfect! Thank you very much!
 ^D
 ....
 
 We have found that while for the focal length of 150, our pinhole diameter should be 490 microns, or 0.49 mm, if we go with the almost identical focal length of 156 mm, we can get away with a pinhole diameter of exactly one half of a millimeter.
 
 [[x86-pinhole-scripting]]
 === Scripting
 
 Because we have chosen the `#` character to denote the start of a comment, we can treat our pinhole software as a _scripting language_.
 
 You have probably seen shell _scripts_ that start with:
 
 [.programlisting]
 ....
 #! /bin/sh
 ....
 
 ...or...
 
 [.programlisting]
 ....
 #!/bin/sh
 ....
 
 ...because the blank space after the `#!` is optional.
 
 Whenever UNIX(R) is asked to run an executable file which starts with the `#!`, it assumes the file is a script.
 It adds the command to the rest of the first line of the script, and tries to execute that.
 
 Suppose now that we have installed pinhole in /usr/local/bin/, we can now write a script to calculate various pinhole diameters suitable for various focal lengths commonly used with the 120 film.
 
 The script might look something like this:
 
 [.programlisting]
 ....
 #! /usr/local/bin/pinhole -b -i
 # Find the best pinhole diameter
 # for the 120 film
 
 ### Standard
 80
 
 ### Wide angle
 30, 40, 50, 60, 70
 
 ### Telephoto
 100, 120, 140
 ....
 
 Because 120 is a medium size film, we may name this file medium.
 
 We can set its permissions to execute, and run it as if it were a program:
 
 [source,shell]
 ....
 % chmod 755 medium
 % ./medium
 ....
 
 UNIX(R) will interpret that last command as:
 
 [source,shell]
 ....
 % /usr/local/bin/pinhole -b -i ./medium
 ....
 
 It will run that command and display:
 
 [source,shell]
 ....
 80	358	224	256	1562	11
 30	219	137	128	586	9
 40	253	158	181	781	10
 50	283	177	181	977	10
 60	310	194	181	1172	10
 70	335	209	181	1367	10
 100	400	250	256	1953	11
 120	438	274	256	2344	11
 140	473	296	256	2734	11
 ....
 
 Now, let us enter:
 
 [source,shell]
 ....
 % ./medium -c
 ....
 
 UNIX(R) will treat that as:
 
 [source,shell]
 ....
 % /usr/local/bin/pinhole -b -i ./medium -c
 ....
 
 That gives it two conflicting options: `-b` and `-c` (Use Bender's constant and use Connors' constant).
 We have programmed it so later options override early ones-our program will calculate everything using Connors' constant:
 
 [source,shell]
 ....
 80	331	242	256	1826	11
 30	203	148	128	685	9
 40	234	171	181	913	10
 50	262	191	181	1141	10
 60	287	209	181	1370	10
 70	310	226	256	1598	11
 100	370	270	256	2283	11
 120	405	296	256	2739	11
 140	438	320	362	3196	12
 ....
 
 We decide we want to go with Bender's constant after all.
 We want to save its values as a comma-separated file:
 
 [source,shell]
 ....
 % ./medium -b -e > bender
 % cat bender
 focal length in millimeters,pinhole diameter in microns,F-number,normalized F-number,F-5.6 multiplier,stops from F-5.6
 80,358,224,256,1562,11
 30,219,137,128,586,9
 40,253,158,181,781,10
 50,283,177,181,977,10
 60,310,194,181,1172,10
 70,335,209,181,1367,10
 100,400,250,256,1953,11
 120,438,274,256,2344,11
 140,473,296,256,2734,11
 %
 ....
 
 [[x86-caveats]]
 == Caveats
 
 Assembly language programmers who "grew up" under MS-DOS(R) and Windows(R) often tend to take shortcuts.
 Reading the keyboard scan codes and writing directly to video memory are two classical examples of practices which, under MS-DOS(R) are not frowned upon but considered the right thing to do.
 
 The reason? Both the PC BIOS and MS-DOS(R) are notoriously slow when performing these operations.
 
 You may be tempted to continue similar practices in the UNIX(R) environment.
 For example, I have seen a web site which explains how to access the keyboard scan codes on a popular UNIX(R) clone.
 
 That is generally a _very bad idea_ in UNIX(R) environment! Let me explain why.
 
 [[x86-protected]]
 === UNIX(R) Is Protected
 
 For one thing, it may simply not be possible.
 UNIX(R) runs in protected mode.
 Only the kernel and device drivers are allowed to access hardware directly.
 Perhaps a particular UNIX(R) clone will let you read the keyboard scan codes, but chances are a real UNIX(R) operating system will not.
 And even if one version may let you do it, the next one may not, so your carefully crafted software may become a dinosaur overnight.
 
 [[x86-abstraction]]
 === UNIX(R) Is an Abstraction
 
 But there is a much more important reason not to try accessing the hardware directly (unless, of course, you are writing a device driver), even on the UNIX(R) like systems that let you do it:
 
 _UNIX(R) is an abstraction!_
 
 There is a major difference in the philosophy of design between MS-DOS(R) and UNIX(R).
 MS-DOS(R) was designed as a single-user system.
 It is run on a computer with a keyboard and a video screen attached directly to that computer.
 User input is almost guaranteed to come from that keyboard.
 Your program's output virtually always ends up on that screen.
 
 This is NEVER guaranteed under UNIX(R).
 It is quite common for a UNIX(R) user to pipe and redirect program input and output:
 
 [source,shell]
 ....
 % program1 | program2 | program3 > file1
 ....
 
 If you have written program2, your input does not come from the keyboard but from the output of program1.
 Similarly, your output does not go to the screen but becomes the input for program3 whose output, in turn, goes to [.filename]#file1#.
 
 But there is more! Even if you made sure that your input comes from, and your output goes to, the terminal, there is no guarantee the terminal is a PC: It may not have its video memory where you expect it, nor may its keyboard be producing PC-style scan codes.
 It may be a Macintosh(R), or any other computer.
 
 Now you may be shaking your head: My software is in PC assembly language, how can it run on a Macintosh(R)? But I did not say your software would be running on a Macintosh(R), only that its terminal may be a Macintosh(R).
 
 Under UNIX(R), the terminal does not have to be directly attached to the computer that runs your software, it can even be on another continent, or, for that matter, on another planet.
 It is perfectly possible that a Macintosh(R) user in Australia connects to a UNIX(R) system in North America (or anywhere else) via telnet.
 The software then runs on one computer, while the terminal is on a different computer: If you try to read the scan codes, you will get the wrong input!
 
 Same holds true about any other hardware: A file you are reading may be on a disk you have no direct access to.
 A camera you are reading images from may be on a space shuttle, connected to you via satellites.
 
 That is why under UNIX(R) you must never make any assumptions about where your data is coming from and going to.
 Always let the system handle the physical access to the hardware.
 
 [NOTE]
 ====
 These are caveats, not absolute rules.
 Exceptions are possible.
 For example, if a text editor has determined it is running on a local machine, it may want to read the scan codes directly for improved control.
 I am not mentioning these caveats to tell you what to do or what not to do, just to make you aware of certain pitfalls that await you if you have just arrived to UNIX(R) form MS-DOS(R).
 Of course, creative people often break rules, and it is OK as long as they know they are breaking them and why.
 ====
 
 [[x86-acknowledgements]]
 == Acknowledgements
 
 This tutorial would never have been possible without the help of many experienced FreeBSD programmers from the {freebsd-hackers}, many of whom have patiently answered my questions, and pointed me in the right direction in my attempts to explore the inner workings of UNIX(R) system programming in general and FreeBSD in particular.
 
 Thomas M. Sommers opened the door for me .
 His https://web.archive.org/web/20090914064615/http://www.codebreakers-journal.com/content/view/262/27[How do I write "Hello, world" in FreeBSD assembler?] web page was my first encounter with an example of assembly language programming under FreeBSD.
 
 Jake Burkholder has kept the door open by willingly answering all of my questions and supplying me with example assembly language source code.
 
 Copyright (R) 2000-2001 G. Adam Stanislav. All rights reserved.
diff --git a/documentation/content/en/books/faq/_index.adoc b/documentation/content/en/books/faq/_index.adoc
index c487cc8942..5f5554c60f 100644
--- a/documentation/content/en/books/faq/_index.adoc
+++ b/documentation/content/en/books/faq/_index.adoc
@@ -1,2644 +1,2644 @@
 ---
 title: Frequently Asked Questions for FreeBSD 11.X, 12.X, and 13.X
 authors: 
   - author: The FreeBSD Documentation Project
 copyright: 1995-2021 The FreeBSD Documentation Project
 description: Frequently Asked Questions, and answers, covering all aspects of FreeBSD
 trademarks: ["freebsd", "ibm", "ieee", "adobe", "intel", "linux", "microsoft", "opengroup", "sun", "netbsd", "general"] 
 weight: 5
 tags: ["FAQ", "FreeBSD FAQ"]
 ---
 
 = Frequently Asked Questions for FreeBSD {rel2-relx} and {rel-relx}
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnums:
 :sectnumlevels: 6
 :partnums:
 :chapter-signifier: Chapter
 :part-signifier: Part
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :rel-numbranch: 4
 :rel-head: 14-CURRENT
 :rel-head-relx: 14.X
 :rel-head-releng: head/
 :rel-relx: 13.X
 :rel-stable: 13-STABLE
 :rel-releng: stable/13/
 :rel-relengdate: December 2018
 :rel2-relx: 12.X
 :rel2-stable: 12-STABLE
 :rel2-releng: stable/12/
 :rel2-relengdate: December 2018
 :rel3-relx: 11.X
 :rel3-stable: 11-STABLE
 :rel3-releng: stable/11/
 :rel3-relengdate: October 2016
 
 
 ifeval::["{backend}" == "html5"]
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
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 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 endif::[]
 
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 [.abstract-title]
 Abstract
 
 This is the Frequently Asked Questions (FAQ) for FreeBSD versions {rel-relx}, {rel2-relx}, and {rel3-relx}. Every effort has been made to make this FAQ as informative as possible; if you have any suggestions as to how it may be improved, send them to the {freebsd-doc}.
 
 The latest version of this document is always available from the link:{faq}[FreeBSD website]. It may also be downloaded as one large link:.[HTML] file with HTTP or as a variety of other formats from the https://download.freebsd.org/ftp/doc/[FreeBSD FTP server].
 
 '''
 
 toc::[]
 
 [[introduction]]
 == Introduction
 
 [[what-is-FreeBSD]]
 === What is FreeBSD?
 
 FreeBSD is a modern operating system for desktops, laptops, servers, and embedded systems with support for a large number of https://www.FreeBSD.org/platforms/[platforms].
 
 It is based on U.C. Berkeley's "4.4BSD-Lite" release, with some "4.4BSD-Lite2" enhancements. It is also based indirectly on William Jolitz's port of U.C. Berkeley's "Net/2" to the i386(TM), known as "386BSD", though very little of the 386BSD code remains.
 
 FreeBSD is used by companies, Internet Service Providers, researchers, computer professionals, students and home users all over the world in their work, education and recreation.
 
 For more detailed information on FreeBSD, refer to the link:{handbook}[FreeBSD Handbook].
 
 [[FreeBSD-goals]]
 === What is the goal of the FreeBSD Project?
 
 The goal of the FreeBSD Project is to provide a stable and fast general purpose operating system that may be used for any purpose without strings attached.
 
 [[bsd-license-restrictions]]
 === Does the FreeBSD license have any restrictions?
 
 Yes. Those restrictions do not control how the code is used, but how to treat the FreeBSD Project itself. The license itself is available at https://www.FreeBSD.org/copyright/freebsd-license/[license] and can be summarized like this:
 
 * Do not claim that you wrote this.
 * Do not sue us if it breaks.
 * Do not remove or modify the license.
 
 Many of us have a significant investment in the project and would certainly not mind a little financial compensation now and then, but we definitely do not insist on it. We believe that our first and foremost "mission" is to provide code to any and all comers, and for whatever purpose, so that the code gets the widest possible use and provides the widest possible benefit. This, we believe, is one of the most fundamental goals of Free Software and one that we enthusiastically support.
 
 Code in our source tree which falls under the https://www.FreeBSD.org/copyright/COPYING[GNU General Public License (GPL)] or https://www.FreeBSD.org/copyright/COPYING.LIB[GNU Library General Public License (LGPL)] comes with slightly more strings attached, though at least on the side of enforced access rather than the usual opposite. Due to the additional complexities that can evolve in the commercial use of GPL software, we do, however, endeavor to replace such software with submissions under the more relaxed https://www.FreeBSD.org/copyright/freebsd-license/[FreeBSD license] whenever possible.
 
 [[replace-current-OS]]
 === Can FreeBSD replace my current operating system?
 
 For most people, yes. But this question is not quite that cut-and-dried.
 
 Most people do not actually use an operating system. They use applications. The applications are what really use the operating system. FreeBSD is designed to provide a robust and full-featured environment for applications. It supports a wide variety of web browsers, office suites, email readers, graphics programs, programming environments, network servers, and much more. Most of these applications can be managed through the https://www.FreeBSD.org/ports/[Ports Collection].
 
 If an application is only available on one operating system, that operating system cannot just be replaced. Chances are, there is a very similar application on FreeBSD, however. As a solid office or Internet server or a reliable workstation, FreeBSD will almost certainly do everything you need. Many computer users across the world, including both novices and experienced UNIX(R) administrators, use FreeBSD as their only desktop operating system.
 
 Users migrating to FreeBSD from another UNIX(R)-like environment will find FreeBSD to be similar. Windows(R) and Mac OS(R) users may be interested in instead using https://www.ghostbsd.org/[GhostBSD], https://www.midnightbsd.org/[MidnightBSD] or  https://www.nomadbsd.org/[NomadBSD] three FreeBSD-based desktop distributions. Non-UNIX(R) users should expect to invest some additional time learning the UNIX(R) way of doing things. This FAQ and the link:{handbook}[FreeBSD Handbook] are excellent places to start.
 
 [[why-called-FreeBSD]]
 === Why is it called FreeBSD?
 
 * It may be used free of charge, even by commercial users.
 * Full source for the operating system is freely available, and the minimum possible restrictions have been placed upon its use, distribution and incorporation into other work (commercial or non-commercial).
 * Anyone who has an improvement or bug fix is free to submit their code and have it added to the source tree (subject to one or two obvious provisions).
 
 It is worth pointing out that the word "free" is being used in two ways here: one meaning "at no cost" and the other meaning "do whatever you like". Apart from one or two things you _cannot_ do with the FreeBSD code, for example pretending you wrote it, you can really do whatever you like with it.
 
 [[differences-to-other-bsds]]
 === What are the differences between FreeBSD and NetBSD, OpenBSD, and other open source BSD operating systems?
 
 James Howard wrote a good explanation of the history and differences between the various projects, called https://jameshoward.us/archive/bsd-family-tree/[The BSD Family Tree] which goes a fair way to answering this question. Some of the information is out of date, but the history portion in particular remains accurate.
 
 Most of the BSDs share patches and code, even today. All of the BSDs have common ancestry.
 
 The design goals of FreeBSD are described in <<FreeBSD-goals>>, above. The design goals of the other most popular BSDs may be summarized as follows:
 
 * OpenBSD aims for operating system security above all else. The OpenBSD team wrote man:ssh[1] and man:pf[4], which have both been ported to FreeBSD.
 * NetBSD aims to be easily ported to other hardware platforms.
 * DragonFly BSD is a fork of FreeBSD 4.8 that has since developed many interesting features of its own, including the HAMMER file system and support for user-mode "vkernels".
 
 [[latest-version]]
 === What is the latest version of FreeBSD?
 
 At any point in the development of FreeBSD, there can be multiple parallel branches. {rel-relx} releases are made from the {rel-stable} branch, and {rel2-relx} releases are made from the {rel2-stable} branch.
 
 Up until the release of 12.0, the {rel2-relx} series was the one known as _-STABLE_. However, as of {rel-head-relx}, the {rel2-relx} branch will be designated for an "extended support" status and receive only fixes for major problems, such as security-related fixes. 
 
 Releases are made <<release-freq,every few months>>. While many people stay more up-to-date with the FreeBSD sources (see the questions on <<current,FreeBSD-CURRENT>> and <<stable,FreeBSD-STABLE>>) than that, doing so is more of a commitment, as the sources are a moving target.
 
 More information on FreeBSD releases can be found on the https://www.FreeBSD.org/releng/#release-build[Release Engineering page] and in man:release[7].
 
 [[current]]
 === What is _FreeBSD-CURRENT_?
 
 link:{handbook}#current[FreeBSD-CURRENT] is the development version of the operating system, which will in due course become the new FreeBSD-STABLE branch. As such, it is really only of interest to developers working on the system and die-hard hobbyists. See the link:{handbook}#current[relevant section] in the link:{handbook}[Handbook] for details on running _-CURRENT_.
 
 Users not familiar with FreeBSD should not use FreeBSD-CURRENT. This branch sometimes evolves quite quickly and due to mistake can be un-buildable at times. People that use FreeBSD-CURRENT are expected to be able to analyze, debug, and report problems.
 
 [[stable]]
 === What is the FreeBSD-STABLE concept?
 
 _FreeBSD-STABLE_ is the development branch from which major releases are made. Changes go into this branch at a slower pace and with the general assumption that they have first been tested in FreeBSD-CURRENT. However, at any given time, the sources for FreeBSD-STABLE may or may not be suitable for general use, as it may uncover bugs and corner cases that were not yet found in FreeBSD-CURRENT. Users who do not have the resources to perform testing should instead run the most recent release of FreeBSD. _FreeBSD-CURRENT_, on the other hand, has been one unbroken line since 2.0 was released.
 
 For more detailed information on branches see "link:{releng}#rel-branch[FreeBSD Release Engineering: Creating the Release Branch]", the status of the branches and the upcoming release schedule can be found on the https://www.FreeBSD.org/releng[Release Engineering Information] page.
 
 Version https://download.FreeBSD.org/ftp/releases/amd64/amd64/{rel121-current}-RELEASE/[{rel121-current}] is the latest release from the {rel-stable} branch; it was released in {rel121-current-date}. Version https://download.FreeBSD.org/ftp/releases/amd64/amd64/{rel113-current}-RELEASE/[{rel113-current}] is the latest release from the {rel2-stable} branch; it was released in {rel113-current-date}.
 
 [[release-freq]]
 === When are FreeBSD releases made?
 
 The {re} releases a new major version of FreeBSD about every 18 months and a new minor version about every 8 months, on average. Release dates are announced well in advance, so that the people working on the system know when their projects need to be finished and tested. A testing period precedes each release, to ensure that the addition of new features does not compromise the stability of the release. Many users regard this caution as one of the best things about FreeBSD, even though waiting for all the latest goodies to reach _-STABLE_ can be a little frustrating.
 
 More information on the release engineering process (including a schedule of upcoming releases) can be found on the https://www.FreeBSD.org/releng/[release engineering] pages on the FreeBSD Web site.
 
 For people who need or want a little more excitement, binary snapshots are made weekly as discussed above.
 
 [[snapshot-freq]]
 === When are FreeBSD snapshots made?
 
 FreeBSD link:https://www.FreeBSD.org/snapshots/[snapshot] releases are made based on the current state of the _-CURRENT_ and _-STABLE_ branches. The goals behind each snapshot release are:
 
 * To test the latest version of the installation software.
 * To give people who would like to run _-CURRENT_ or _-STABLE_ but who do not have the time or bandwidth to follow it on a day-to-day basis an easy way of bootstrapping it onto their systems.
 * To preserve a fixed reference point for the code in question, just in case we break something really badly later. (Although Subversion normally prevents anything horrible like this happening.)
 * To ensure that all new features and fixes in need of testing have the greatest possible number of potential testers.
 
 No claims are made that any _-CURRENT_ snapshot can be considered "production quality" for any purpose. If a stable and fully tested system is needed, stick to full releases.
 
 Snapshot releases are directly available from link:https://www.FreeBSD.org/snapshots/[snapshot].
 
 Official snapshots are generated on a regular basis for all actively developed branches.
 
 [[responsible]]
 === Who is responsible for FreeBSD?
 
 The key decisions concerning the FreeBSD project, such as the overall direction of the project and who is allowed to add code to the source tree, are made by a link:https://www.FreeBSD.org/administration#t-core[core team] of 9 people. There is a much larger team of more than 350 link:{contributors}#staff-committers[committers] who are authorized to make changes directly to the FreeBSD source tree.
 
 However, most non-trivial changes are discussed in advance in the <<mailing,mailing lists>>, and there are no restrictions on who may take part in the discussion.
 
 [[where-get]]
 === Where can I get FreeBSD?
 
 Every significant release of FreeBSD is available via anonymous FTP from the https://download.FreeBSD.org/ftp/releases/[FreeBSD FTP site]:
 
 * The latest {rel-stable} release, {rel121-current}-RELEASE can be found in the https://download.FreeBSD.org/ftp/releases/amd64/amd64/{rel121-current}-RELEASE/[{rel121-current}-RELEASE directory].
 * link:https://www.FreeBSD.org/snapshots/[Snapshot] releases are made monthly for the <<current,-CURRENT>> and <<stable,-STABLE>> branch, these being of service purely to bleeding-edge testers and developers.
 * The latest {rel2-stable} release, {rel113-current}-RELEASE can be found in the https://download.FreeBSD.org/ftp/releases/amd64/amd64/{rel113-current}-RELEASE/[{rel113-current}-RELEASE directory].
 
 Information about obtaining FreeBSD on CD, DVD, and other media can be found in link:{handbook}#mirrors/[the Handbook].
 
 [[access-pr]]
 === How do I access the Problem Report database?
 
 The Problem Report database of all user change requests may be queried by using our web-based PR https://bugs.FreeBSD.org/search/[query] interface.
 
 The link:https://www.FreeBSD.org/support/bugreports[web-based problem report submission interface] can be used to submit problem reports through a web browser.
 
 Before submitting a problem report, read link:{problem-reports}[Writing FreeBSD Problem Reports], an article on how to write good problem reports.
 
 [[support]]
 == Documentation and Support
 
 [[books]]
 === What good books are there about FreeBSD?
 
 The project produces a wide range of documentation, available online from this link: https://www.FreeBSD.org/docs/[https://www.FreeBSD.org/docs/]. 
 
 [[doc-formats]]
 === Is the documentation available in other formats, such as plain text (ASCII), or PDF?
 
 Yes. The documentation is available in a number of different formats and compression schemes on the FreeBSD FTP site, in the https://download.freebsd.org/ftp/doc/[/ftp/doc/] directory.
 
 The documentation is categorized in a number of different ways. These include:
 
 * The document's name, such as `faq`, or `handbook`.
 * The document's language and encoding. These are based on the locale names found under [.filename]#/usr/share/locale# on a FreeBSD system. The current languages and encodings are as follows:
 +
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Meaning
 
 |`en_US.ISO8859-1`
 |English (United States)
 
 |`bn_BD.ISO10646-1`
 |Bengali or Bangla (Bangladesh)
 
 |`da_DK.ISO8859-1`
 |Danish (Denmark)
 
 |`de_DE.ISO8859-1`
 |German (Germany)
 
 |`el_GR.ISO8859-7`
 |Greek (Greece)
 
 |`es_ES.ISO8859-1`
 |Spanish (Spain)
 
 |`fr_FR.ISO8859-1`
 |French (France)
 
 |`hu_HU.ISO8859-2`
 |Hungarian (Hungary)
 
 |`it_IT.ISO8859-15`
 |Italian (Italy)
 
 |`ja_JP.eucJP`
 |Japanese (Japan, EUC encoding)
 
 |`ko_KR.UTF-8`
 |Korean (Korea, UTF-8 encoding)
 
 |`mn_MN.UTF-8`
 |Mongolian (Mongolia, UTF-8 encoding)
 
 |`nl_NL.ISO8859-1`
 |Dutch (Netherlands)
 
 |`pl_PL.ISO8859-2`
 |Polish (Poland)
 
 |`pt_BR.ISO8859-1`
 |Portuguese (Brazil)
 
 |`ru_RU.KOI8-R`
 |Russian (Russia, KOI8-R encoding)
 
 |`tr_TR.ISO8859-9`
 |Turkish (Turkey)
 
 |`zh_CN.UTF-8`
 |Simplified Chinese (China, UTF-8 encoding)
 
 |`zh_TW.UTF-8`
 |Traditional Chinese (Taiwan, UTF-8 encoding)
 |===
 +
 [NOTE]
 ====
 Some documents may not be available in all languages.
 ====
 
 * The document's format. We produce the documentation in a number of different output formats. Each format has its own advantages and disadvantages. Some formats are better suited for online reading, while others are meant to be aesthetically pleasing when printed on paper. Having the documentation available in any of these formats ensures that our readers will be able to read the parts they are interested in, either on their monitor, or on paper after printing the documents. The currently available formats are:
 +
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | Format
 | Meaning
 
 |`html-split`
 |A collection of small, linked, HTML files.
 
 |`html`
 |One large HTML file containing the entire document
 
 |`pdf`
 |Adobe's Portable Document Format
 
 |`txt`
 |Plain text
 |===
 * The compression and packaging scheme.
 .. Where the format is `html-split`, the files are bundled up using man:tar[1]. The resulting [.filename]#.tar# is then compressed using the compression schemes detailed in the next point.
 .. All the other formats generate one file. For example, [.filename]#article.pdf#, [.filename]#book.html#, and so on.
-+ 
++
 These files are then compressed using either the `zip` or `bz2` compression schemes. man:tar[1] can be used to uncompress these files.
-+ 
++
 So the PDF version of the Handbook, compressed using `bzip2` will be stored in a file called [.filename]#book.pdf.bz2# in the [.filename]#handbook/# directory.
 
 After choosing the format and compression mechanism, download the compressed files, uncompress them, and then copy the appropriate documents into place.
 
 For example, the split HTML version of the FAQ, compressed using man:bzip2[1], can be found in [.filename]#doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2# To download and uncompress that file, type:
 
 [source,shell]
 ....
 # fetch https://download.freebsd.org/ftp/doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2
 # tar xvf book.html-split.tar.bz2
 ....
 
 If the file is compressed, tar will automatically detect the appropriate format and decompress it correctly, resulting in a collection of [.filename]#.html# files. The main one is called [.filename]#index.html#, which will contain the table of contents, introductory material, and links to the other parts of the document.
 
 [[mailing]]
 === Where do I find info on the FreeBSD mailing lists? What FreeBSD news groups are available?
 
 Refer to the link:{handbook}#eresources-mail[Handbook entry on mailing-lists] and the link:{handbook}#eresources-news/[Handbook entry on newsgroups].
 
 [[irc]]
 === Are there FreeBSD IRC (Internet Relay Chat) channels?
 
 Yes, most major IRC networks host a FreeBSD chat channel:
 
 * Channel `#FreeBSDhelp` on http://www.efnet.org/index.php[EFNet] is a channel dedicated to helping FreeBSD users.
 * Channel `#FreeBSD` on http://freenode.net/[Freenode] is a general help channel with many users at any time. The conversations have been known to run off-topic for a while, but priority is given to users with FreeBSD questions. Other users can help with the basics, referring to the Handbook whenever possible and providing links for learning more about a particular topic. This is primarily an English speaking channel, though it does have users from all over the world. Non-native English speakers should try to ask the question in English first and then relocate to `##freebsd-lang` as appropriate.
 * Channel `#FreeBSD` on http://www.dal.net/[DALNET] is available at `irc.dal.net` in the US and `irc.eu.dal.net` in Europe.
 * Channel `#FreeBSD` on http://www.undernet.org/[UNDERNET] is available at `us.undernet.org` in the US and `eu.undernet.org` in Europe. Since it is a help channel, be prepared to read the documents you are referred to.
 * Channel `#FreeBSD` on http://www.rusnet.org.ru/[RUSNET] is a Russian language channel dedicated to helping FreeBSD users. This is also a good place for non-technical discussions.
 * Channel `#bsdchat` on http://freenode.net/[Freenode] is a Traditional Chinese (UTF-8 encoding) language channel dedicated to helping FreeBSD users. This is also a good place for non-technical discussions.
 
 The FreeBSD wiki has a https://wiki.freebsd.org/IRC/Channels[good list] of IRC channels.
 
 Each of these channels are distinct and are not connected to each other. Since their chat styles differ, try each to find one suited to your chat style.
 
 [[forums]]
 === Are there any web based forums to discuss FreeBSD?
 
 The official FreeBSD forums are located at https://forums.FreeBSD.org/[https://forums.FreeBSD.org/].
 
 [[training]]
 === Where can I get commercial FreeBSD training and support?
 
 http://www.ixsystems.com[iXsystems, Inc.], parent company of the http://www.freebsdmall.com/[FreeBSD Mall], provides commercial FreeBSD and TrueOS software http://www.ixsystems.com/support[support], in addition to FreeBSD development and tuning solutions.
 
 BSD Certification Group, Inc. provides system administration certifications for DragonFly BSD, FreeBSD, NetBSD, and OpenBSD. Refer to http://www.BSDCertification.org[their site] for more information.
 
 Any other organizations providing training and support should contact the Project to be listed here.
 
 [[install]]
 == Installation
 
 [[which-architecture]]
 === Which platform should I download? I have a 64 bit capable Intel(R) CPU, but I only see amd64.
 
 amd64 is the term FreeBSD uses for 64-bit compatible x86 architectures (also known as "x86-64" or "x64"). Most modern computers should use amd64. Older hardware should use i386. When installing on a non-x86-compatible architecture, select the platform which best matches the hardware.
 
 [[floppy-download]]
 === Which file do I download to get FreeBSD?
 
 On the https://www.freebsd.org/where/[Getting FreeBSD] page, select `[iso]` next to the architecture that matches the hardware.
 
 Any of the following can be used:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | file
 | description
 
 |[.filename]#disc1.iso#
 |Contains enough to install FreeBSD and a minimal set of packages.
 
 |[.filename]#dvd1.iso#
 |Similar to [.filename]#disc1.iso# but with additional packages.
 
 |[.filename]#memstick.img#
 |A bootable image sufficient for writing to a USB stick.
 
 |[.filename]#bootonly.iso#
 |A minimal image that requires network access during installation to completely install FreeBSD.
 |===
 
 Full instructions on this procedure and a little bit more about installation issues in general can be found in the link:{handbook}#bsdinstall/[Handbook entry on installing FreeBSD].
 
 [[floppy-image-too-large]]
 === What do I do if the install image does not boot?
 
 This can be caused by not downloading the image in _binary_ mode when using FTP.
 
 Some FTP clients default their transfer mode to _ascii_ and attempt to change any end-of-line characters received to match the conventions used by the client's system. This will almost invariably corrupt the boot image. Check the SHA-256 checksum of the downloaded boot image: if it is not _exactly_ that on the server, then the download process is suspect.
 
 When using a command line FTP client, type _binary_ at the FTP command prompt after getting connected to the server and before starting the download of the image.
 
 [[install-instructions-location]]
 === Where are the instructions for installing FreeBSD?
 
 Installation instructions can be found at link:{handbook}#bsdinstall/[Handbook entry on installing FreeBSD].
 
 [[custom-boot-floppy]]
 === How can I make my own custom release or install disk?
 
 Customized FreeBSD installation media can be created by building a custom release. Follow the instructions in the link:{releng}[Release Engineering] article.
 
 [[windows-coexist]]
 === Can Windows(R) co-exist with FreeBSD? (x86-specific)
 
 If Windows(R) is installed first, then yes. FreeBSD's boot manager will then manage to boot Windows(R) and FreeBSD. If Windows(R) is installed afterwards, it will overwrite the boot manager. If that happens, see the next section.
 
 [[bootmanager-restore]]
 === Another operating system destroyed my Boot Manager. How do I get it back? (x86-specific)
 
 This depends upon the boot manager. The FreeBSD boot selection menu can be reinstalled using man:boot0cfg[8]. For example, to restore the boot menu onto the disk _ada0_:
 
 [source,shell]
 ....
 # boot0cfg -B ada0
 ....
 
 The non-interactive MBR bootloader can be installed using man:gpart[8]:
 
 [source,shell]
 ....
 # gpart bootcode -b /boot/mbr ada0
 ....
 
 For more complex situations, including GPT disks, see man:gpart[8].
 
 [[need-complete-sources]]
 === Do I need to install the source?
 
 In general, no. There is nothing in the base system which requires the presence of the source to operate. Some ports, like package:sysutils/lsof[], will not build unless the source is installed. In particular, if the port builds a kernel module or directly operates on kernel structures, the source must be installed.
 
 [[need-kernel]]
 === Do I need to build a kernel?
 
 Usually not. The supplied `GENERIC` kernel contains the drivers an ordinary computer will need. man:freebsd-update[8], the FreeBSD binary upgrade tool, cannot upgrade custom kernels, another reason to stick with the `GENERIC` kernel when possible. For computers with very limited RAM, such as embedded systems, it may be worthwhile to build a smaller custom kernel containing just the required drivers.
 
 [[password-encryption]]
 === Should I use DES, Blowfish, or MD5 passwords and how do I specify which form my users receive?
 
 FreeBSD uses _SHA512_ by default. DES passwords are still available for backwards compatibility with operating systems that still use the less secure password format. FreeBSD also supports the Blowfish and MD5 password formats. Which password format to use for new passwords is controlled by the `passwd_format` login capability in [.filename]#/etc/login.conf#, which takes values of `des`, `blf` (if these are available) or `md5`. See the man:login.conf[5] manual page for more information about login capabilities.
 
 [[ffs-limits]]
 === What are the limits for FFS file systems?
 
 For FFS file systems, the largest file system is practically limited by the amount of memory required to man:fsck[8] the file system. man:fsck[8] requires one bit per fragment, which with the default fragment size of 4 KB equates to 32 MB of memory per TB of disk. This does mean that on architectures which limit userland processes to 2 GB (e.g., i386(TM)), the maximum man:fsck[8]'able filesystem is ~60 TB.
 
 If there was not a man:fsck[8] memory limit the maximum filesystem size would be 2 ^ 64 (blocks) * 32 KB => 16 Exa * 32 KB => 512 ZettaBytes.
 
 The maximum size of a single FFS file is approximately 2 PB with the default block size of 32 KB. Each 32 KB block can point to 4096 blocks. With triple indirect blocks, the calculation is 32 KB * 12 + 32 KB * 4096 + 32 KB * 4096^2 + 32 KB * 4096^3. Increasing the block size to 64 KB will increase the max file size by a factor of 16.
 
 [[archsw-readin-failed-error]]
 === Why do I get an error message, readin failed after compiling and booting a new kernel?
 
 The world and kernel are out of sync. This is not supported. Be sure to use `make buildworld` and `make buildkernel` to update the kernel.
 
 Boot the system by specifying the kernel directly at the second stage, pressing any key when the `|` shows up before loader is started.
 
 [[general-configuration-tool]]
 === Is there a tool to perform post-installation configuration tasks?
 
 Yes. bsdconfig provides a nice interface to configure FreeBSD post-installation.
 
 [[hardware]]
 == Hardware Compatibility
 
 [[compatibility-general]]
 === General
 
 [[which-hardware-to-get]]
 ==== I want to get a piece of hardware for my FreeBSD system. Which model/brand/type is best?
 
 This is discussed continually on the FreeBSD mailing lists but is to be expected since hardware changes so quickly. Read through the Hardware Notes for FreeBSD link:{u-rel121-hardware}[{rel121-current}] or link:{u-rel113-hardware}[{rel113-current}] and search the mailing list https://www.FreeBSD.org/search/#mailinglists[archives] before asking about the latest and greatest hardware. Chances are a discussion about that type of hardware took place just last week.
 
 Before purchasing a laptop, check the archives for {freebsd-questions}, or possibly a specific mailing list for a particular hardware type.
 
 [[memory-upper-limitation]]
 ==== What are the limits for memory?
 
 FreeBSD as an operating system generally supports as much physical memory (RAM) as the platform it is running on does. Keep in mind that different platforms have different limits for memory; for example i386(TM) without PAE supports at most 4 GB of memory (and usually less than that because of PCI address space) and i386(TM) with PAE supports at most 64 GB memory. As of FreeBSD 10, AMD64 platforms support up to 4 TB of physical memory.
 
 [[memory-i386-over-4gb]]
 ==== Why does FreeBSD report less than 4 GB memory when installed on an i386(TM) machine?
 
 The total address space on i386(TM) machines is 32-bit, meaning that at most 4 GB of memory is addressable (can be accessed). Furthermore, some addresses in this range are reserved by hardware for different purposes, for example for using and controlling PCI devices, for accessing video memory, and so on. Therefore, the total amount of memory usable by the operating system for its kernel and applications is limited to significantly less than 4 GB. Usually, 3.2 GB to 3.7 GB is the maximum usable physical memory in this configuration.
 
 To access more than 3.2 GB to 3.7 GB of installed memory (meaning up to 4 GB but also more than 4 GB), a special tweak called PAE must be used. PAE stands for Physical Address Extension and is a way for 32-bit x86 CPUs to address more than 4 GB of memory. It remaps the memory that would otherwise be overlaid by address reservations for hardware devices above the 4 GB range and uses it as additional physical memory (see man:pae[4]). Using PAE has some drawbacks; this mode of memory access is a little bit slower than the normal (without PAE) mode and loadable modules (see man:kld[4]) are not supported. This means all drivers must be compiled into the kernel.
 
 The most common way to enable PAE is to build a new kernel with the special ready-provided kernel configuration file called [.filename]#PAE#, which is already configured to build a safe kernel. Note that some entries in this kernel configuration file are too conservative and some drivers marked as unready to be used with PAE are actually usable. A rule of thumb is that if the driver is usable on 64-bit architectures (like AMD64), it is also usable with PAE. When creating a custom kernel configuration file, PAE can be enabled by adding the following line:
 
 [.programlisting]
 ....
 options       PAE
 ....
 
 PAE is not much used nowadays because most new x86 hardware also supports running in 64-bit mode, known as AMD64 or Intel(R) 64. It has a much larger address space and does not need such tweaks. FreeBSD supports AMD64 and it is recommended that this version of FreeBSD be used instead of the i386(TM) version if 4 GB or more memory is required.
 
 [[compatibility-processors]]
 === Architectures and Processors
 
 [[architectures]]
 ==== Does FreeBSD support architectures other than the x86?
 
 Yes. FreeBSD divides support into multiple tiers. Tier 1 architectures, such as i386 or amd64; are fully supported. Tiers 2 and 3 are supported on a best-effort basis. A full explanation of the tier system is available in the link:{committers-guide}#archs/[Committer's Guide.]
 
 A complete list of supported architectures can be found on the https://www.FreeBSD.org/platforms/[platforms page.]
 
 [[smp-support]]
 ==== Does FreeBSD support Symmetric Multiprocessing (SMP)?
 
 FreeBSD supports symmetric multi-processor (SMP) on all non-embedded platforms (e.g, i386, amd64, etc.). SMP is also supported in arm and MIPS kernels, although some CPUs may not support this. FreeBSD's SMP implementation uses fine-grained locking, and performance scales nearly linearly with number of CPUs.
 
 man:smp[4] has more details.
 
 [[microcode]]
 ==== What is microcode? How do I install Intel(R) CPU microcode updates?
 
 Microcode is a method of programmatically implementing hardware level instructions. This allows for CPU bugs to be fixed without replacing the on board chip.
 
 Install package:sysutils/devcpu-data[], then add:
 
 [.programlisting]
 ....
 microcode_update_enable="YES"
 ....
 
 to [.filename]#/etc/rc.conf#
 
 [[compatibility-peripherals]]
 === Peripherals
 
 [[supported-peripherals]]
 ==== What kind of peripherals does FreeBSD support?
 
 See the complete list in the Hardware Notes for FreeBSD link:{u-rel121-hardware}[{rel121-current}] or link:{u-rel113-hardware}[{rel113-current}].
 
 [[compatibility-kbd-mice]]
 === Keyboards and Mice
 
 [[moused]]
 ==== Is it possible to use a mouse outside the X Window system?
 
 The default console driver, man:vt[4], provides the ability to use a mouse pointer in text consoles to cut & paste text. Run the mouse daemon, man:moused[8], and turn on the mouse pointer in the virtual console:
 
 [source,shell]
 ....
 # moused -p /dev/xxxx -t yyyy
 # vidcontrol -m on
 ....
 
 Where _xxxx_ is the mouse device name and _yyyy_ is a protocol type for the mouse. The mouse daemon can automatically determine the protocol type of most mice, except old serial mice. Specify the `auto` protocol to invoke automatic detection. If automatic detection does not work, see the man:moused[8] manual page for a list of supported protocol types.
 
 For a PS/2 mouse, add `moused_enable="YES"` to [.filename]#/etc/rc.conf# to start the mouse daemon at boot time. Additionally, to use the mouse daemon on all virtual terminals instead of just the console, add `allscreens_flags="-m on"` to [.filename]#/etc/rc.conf#.
 
 When the mouse daemon is running, access to the mouse must be coordinated between the mouse daemon and other programs such as X Windows. Refer to the FAQ<<x-and-moused,Why does my mouse not work with X?>> for more details on this issue.
 
 [[text-mode-cut-paste]]
 ==== How do I cut and paste text with a mouse in the text console?
 
 It is not possible to remove data using the mouse. However, it is possible to copy and paste. Once the mouse daemon is running as described in the <<moused,previous question>>, hold down button 1 (left button) and move the mouse to select a region of text. Then, press button 2 (middle button) to paste it at the text cursor. Pressing button 3 (right button) will "extend" the selected region of text.
 
 If the mouse does not have a middle button, it is possible to emulate one or remap buttons using mouse daemon options. See the man:moused[8] manual page for details.
 
 [[mouse-wheel-buttons]]
 ==== My mouse has a fancy wheel and buttons. Can I use them in FreeBSD?
 
 The answer is, unfortunately, "It depends". These mice with additional features require specialized driver in most cases. Unless the mouse device driver or the user program has specific support for the mouse, it will act just like a standard two, or three button mouse.
 
 For the possible usage of wheels in the X Window environment, refer to <<x-and-wheel,that section>>.
 
 [[keyboard-delete-key]]
 ==== How do I use my delete key in sh and csh?
 
 For the Bourne Shell, add the following lines to [.filename]#~/.shrc#. See man:sh[1] and man:editrc[5].
 
 [.programlisting]
 ....
 bind ^[[3~ ed-delete-next-char # for xterm
 ....
 
 For the C Shell, add the following lines to [.filename]#~/.cshrc#. See man:csh[1].
 
 [.programlisting]
 ....
 bindkey ^[[3~ delete-char # for xterm
 ....
 
 [[compatibility-other]]
 === Other Hardware
 
 [[es1370-silent-pcm]]
 ==== Workarounds for no sound from my man:pcm[4] sound card?
 
 Some sound cards set their output volume to 0 at every boot. Run the following command every time the machine boots:
 
 [source,shell]
 ....
 # mixer pcm 100 vol 100 cd 100
 ....
 
 [[power-management-support]]
 ==== Does FreeBSD support power management on my laptop?
 
 FreeBSD supports the ACPI features found in modern hardware. Further information can be found in man:acpi[4].
 
 [[troubleshoot]]
 == Troubleshooting
 
 [[pae]]
 === Why is FreeBSD finding the wrong amount of memory on i386(TM) hardware?
 
 The most likely reason is the difference between physical memory addresses and virtual addresses.
 
 The convention for most PC hardware is to use the memory area between 3.5 GB and 4 GB for a special purpose (usually for PCI). This address space is used to access PCI hardware. As a result real, physical memory cannot be accessed by that address space.
 
 What happens to the memory that should appear in that location is hardware dependent. Unfortunately, some hardware does nothing and the ability to use that last 500 MB of RAM is entirely lost.
 
 Luckily, most hardware remaps the memory to a higher location so that it can still be used. However, this can cause some confusion when watching the boot messages.
 
 On a 32-bit version of FreeBSD, the memory appears lost, since it will be remapped above 4 GB, which a 32-bit kernel is unable to access. In this case, the solution is to build a PAE enabled kernel. See the entry on memory limits for more information.
 
 On a 64-bit version of FreeBSD, or when running a PAE-enabled kernel, FreeBSD will correctly detect and remap the memory so it is usable. During boot, however, it may seem as if FreeBSD is detecting more memory than the system really has, due to the described remapping. This is normal and the available memory will be corrected as the boot process completes.
 
 [[signal11]]
 === Why do my programs occasionally die with Signal 11 errors?
 
 Signal 11 errors are caused when a process has attempted to access memory which the operating system has not granted it access to. If something like this is happening at seemingly random intervals, start investigating the cause.
 
 These problems can usually be attributed to either:
 
 . If the problem is occurring only in a specific custom application, it is probably a bug in the code.
 . If it is a problem with part of the base FreeBSD system, it may also be buggy code, but more often than not these problems are found and fixed long before us general FAQ readers get to use these bits of code (that is what -CURRENT is for).
 
 It is probably not a FreeBSD bug if the problem occurs compiling a program, but the activity that the compiler is carrying out changes each time.
 
 For example, if `make buildworld` fails while trying to compile [.filename]#ls.c# into [.filename]#ls.o# and, when run again, it fails in the same place, this is a broken build. Try updating source and try again. If the compile fails elsewhere, it is almost certainly due to hardware.
 
 In the first case, use a debugger such as man:gdb[1] to find the point in the program which is attempting to access a bogus address and fix it.
 
 In the second case, verify which piece of hardware is at fault.
 
 Common causes of this include:
 
 . The hard disks might be overheating: Check that the fans are still working, as the disk and other hardware might be overheating.
 . The processor running is overheating: This might be because the processor has been overclocked, or the fan on the processor might have died. In either case, ensure that the hardware is running at what it is specified to run at, at least while trying to solve this problem. If it is not, clock it back to the default settings.)
-+ 
++
 Regarding overclocking, it is far cheaper to have a slow system than a fried system that needs replacing! Also the community is not sympathetic to problems on overclocked systems.
 . Dodgy memory: if multiple memory SIMMS/DIMMS are installed, pull them all out and try running the machine with each SIMM or DIMM individually to narrow the problem down to either the problematic DIMM/SIMM or perhaps even a combination.
 . Over-optimistic motherboard settings: the BIOS settings, and some motherboard jumpers, provide options to set various timings. The defaults are often sufficient, but sometimes setting the wait states on RAM too low, or setting the "RAM Speed: Turbo" option will cause strange behavior. A possible idea is to set to BIOS defaults, after noting the current settings first.
 . Unclean or insufficient power to the motherboard. Remove any unused I/O boards, hard disks, or CD-ROMs, or disconnect the power cable from them, to see if the power supply can manage a smaller load. Or try another power supply, preferably one with a little more power. For instance, if the current power supply is rated at 250 Watts, try one rated at 300 Watts.
 
 Read the section on <<signal11,Signal 11>> for a further explanation and a discussion on how memory testing software or hardware can still pass faulty memory. There is an extensive FAQ on this at http://www.bitwizard.nl/sig11/[the SIG11 problem FAQ].
 
 Finally, if none of this has helped, it is possibly a bug in FreeBSD. Follow <<access-pr,these instructions>> to send a problem report.
 
 [[trap-12-panic]]
 === My system crashes with either Fatal trap 12: page fault in kernel mode, or panic:, and spits out a bunch of information. What should I do?
 
 The FreeBSD developers are interested in these errors, but need more information than just the error message. Copy the full crash message. Then consult the FAQ section on <<kernel-panic-troubleshooting,kernel panics>>, build a debugging kernel, and get a backtrace. This might sound difficult, but does not require any programming skills. Just follow the instructions.
 
 [[proc-table-full]]
 === What is the meaning of the error maxproc limit exceeded by uid %i, please see tuning(7) and login.conf(5)?
 
 The FreeBSD kernel will only allow a certain number of processes to exist at one time. The number is based on the `kern.maxusers` man:sysctl[8] variable. `kern.maxusers` also affects various other in-kernel limits, such as network buffers. If the machine is heavily loaded, increase `kern.maxusers`. This will increase these other system limits in addition to the maximum number of processes.
 
 To adjust the `kern.maxusers` value, see the link:{handbook}#kern-maxfiles[File/Process Limits] section of the Handbook. While that section refers to open files, the same limits apply to processes.
 
 If the machine is lightly loaded but running a very large number of processes, adjust the `kern.maxproc` tunable by defining it in [.filename]#/boot/loader.conf#. The tunable will not get adjusted until the system is rebooted. For more information about tuning tunables, see man:loader.conf[5]. If these processes are being run by a single user, adjust `kern.maxprocperuid` to be one less than the new `kern.maxproc` value. It must be at least one less because one system program, man:init[8], must always be running.
 
 [[remote-fullscreen]]
 === Why do full screen applications on remote machines misbehave?
 
 The remote machine may be setting the terminal type to something other than `xterm` which is required by the FreeBSD console. Alternatively the kernel may have the wrong values for the width and height of the terminal.
 
 Check the value of the `TERM` environment variable is `xterm`. If the remote machine does not support that try `vt100`.
 
 Run `stty -a` to check what the kernel thinks the terminal dimensions are. If they are incorrect, they can be changed by running `stty rows _RR_ cols _CC_`.
 
 Alternatively, if the client machine has package:x11/xterm[] installed, then running `resize` will query the terminal for the correct dimensions and set them.
 
 [[connection-delay]]
 === Why does it take so long to connect to my computer via ssh or telnet?
 
 The symptom: there is a long delay between the time the TCP connection is established and the time when the client software asks for a password (or, in man:telnet[1]'s case, when a login prompt appears).
 
 The problem: more likely than not, the delay is caused by the server software trying to resolve the client's IP address into a hostname. Many servers, including the Telnet and SSH servers that come with FreeBSD, do this to store the hostname in a log file for future reference by the administrator.
 
 The remedy: if the problem occurs whenever connecting the client computer to any server, the problem is with the client. If the problem only occurs when someone connects to the server computer, the problem is with the server.
 
 If the problem is with the client, the only remedy is to fix the DNS so the server can resolve it. If this is on a local network, consider it a server problem and keep reading. If this is on the Internet, contact your ISP.
 
 If the problem is with the server on a local network, configure the server to resolve address-to-hostname queries for the local address range. See man:hosts[5] and man:named[8] for more information. If this is on the Internet, the problem may be that the local server's resolver is not functioning correctly. To check, try to look up another host such as `www.yahoo.com`. If it does not work, that is the problem.
 
 Following a fresh install of FreeBSD, it is also possible that domain and name server information is missing from [.filename]#/etc/resolv.conf#. This will often cause a delay in SSH, as the option `UseDNS` is set to `yes` by default in [.filename]#/etc/ssh/sshd_config#. If this is causing the problem, either fill in the missing information in [.filename]#/etc/resolv.conf# or set `UseDNS` to `no` in [.filename]#sshd_config# as a temporary workaround.
 
 [[file-table-full]]
 === Why does file: table is full show up repeatedly in man:dmesg[8]?
 
 This error message indicates that the number of available file descriptors have been exhausted on the system. Refer to the link:{handbook}#kern-maxfiles[kern.maxfiles] section of the link:{handbook}#configtuning-kernel-limits/[Tuning Kernel Limits] section of the Handbook for a discussion and solution.
 
 [[computer-clock-skew]]
 === Why does the clock on my computer keep incorrect time?
 
 The computer has two or more clocks, and FreeBSD has chosen to use the wrong one.
 
 Run man:dmesg[8], and check for lines that contain `Timecounter`. The one with the highest quality value that FreeBSD chose.
 
 [source,shell]
 ....
 # dmesg | grep Timecounter
 Timecounter "i8254" frequency 1193182 Hz quality 0
 Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
 Timecounter "TSC" frequency 2998570050 Hz quality 800
 Timecounters tick every 1.000 msec
 ....
 
 Confirm this by checking the `kern.timecounter.hardware` man:sysctl[3].
 
 [source,shell]
 ....
 # sysctl kern.timecounter.hardware
 kern.timecounter.hardware: ACPI-fast
 ....
 
 It may be a broken ACPI timer. The simplest solution is to disable the ACPI timer in [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 debug.acpi.disabled="timer"
 ....
 
 Or the BIOS may modify the TSC clock-perhaps to change the speed of the processor when running from batteries, or going into a power saving mode, but FreeBSD is unaware of these adjustments, and appears to gain or lose time.
 
 In this example, the `i8254` clock is also available, and can be selected by writing its name to the `kern.timecounter.hardware` man:sysctl[3].
 
 [source,shell]
 ....
 # sysctl kern.timecounter.hardware=i8254
 kern.timecounter.hardware: TSC -> i8254
 ....
 
 The computer should now start keeping more accurate time.
 
 To have this change automatically run at boot time, add the following line to [.filename]#/etc/sysctl.conf#:
 
 [.programlisting]
 ....
 kern.timecounter.hardware=i8254
 ....
 
 [[indefinite-wait-buffer]]
 === What does the error swap_pager: indefinite wait buffer: mean?
 
 This means that a process is trying to page memory from disk, and the page attempt has hung trying to access the disk for more than 20 seconds. It might be caused by bad blocks on the disk drive, disk wiring, cables, or any other disk I/O-related hardware. If the drive itself is bad, disk errors will appear in [.filename]#/var/log/messages# and in the output of `dmesg`. Otherwise, check the cables and connections.
 
 [[lock-order-reversal]]
 === What is a lock order reversal?
 
 The FreeBSD kernel uses a number of resource locks to arbitrate contention for certain resources. When multiple kernel threads try to obtain multiple resource locks, there's always the potential for a deadlock, where two threads have each obtained one of the locks and blocks forever waiting for the other thread to release one of the other locks. This sort of locking problem can be avoided if all threads obtain the locks in the same order.
 
 A run-time lock diagnostic system called man:witness[4], enabled in FreeBSD-CURRENT and disabled by default for stable branches and releases, detects the potential for deadlocks due to locking errors, including errors caused by obtaining multiple resource locks with a different order from different parts of the kernel. The man:witness[4] framework tries to detect this problem as it happens, and reports it by printing a message to the system console about a `lock order reversal` (often referred to also as LOR).
 
 It is possible to get false positives, as man:witness[4] is conservative. A true positive report _does not_ mean that a system is dead-locked; instead it should be understood as a warning that a deadlock could have happened here.
 
 [NOTE]
 ====
 Problematic LORs tend to get fixed quickly, so check the {freebsd-current} before posting to it.
 ====
 
 [[called-with-non-sleepable-locks-held]]
 === What does Called ... with the following non-sleepable locks held mean?
 
 This means that a function that may sleep was called while a mutex (or other unsleepable) lock was held.
 
 The reason this is an error is because mutexes are not intended to be held for long periods of time; they are supposed to only be held to maintain short periods of synchronization. This programming contract allows device drivers to use mutexes to synchronize with the rest of the kernel during interrupts. Interrupts (under FreeBSD) may not sleep. Hence it is imperative that no subsystem in the kernel block for an extended period while holding a mutex.
 
 To catch such errors, assertions may be added to the kernel that interact with the man:witness[4] subsystem to emit a warning or fatal error (depending on the system configuration) when a potentially blocking call is made while holding a mutex.
 
 In summary, such warnings are non-fatal, however with unfortunate timing they could cause undesirable effects ranging from a minor blip in the system's responsiveness to a complete system lockup.
 
 For additional information about locking in FreeBSD see man:locking[9].
 
 [[touch-not-found]]
 === Why does buildworld/installworld die with the message touch: not found?
 
 This error does not mean that the man:touch[1] utility is missing. The error is instead probably due to the dates of the files being set sometime in the future. If the CMOS clock is set to local time, run `adjkerntz -i` to adjust the kernel clock when booting into single-user mode.
 
 [[applications]]
 == User Applications
 
 [[user-apps]]
 === Where are all the user applications?
 
 Refer to link:https://www.FreeBSD.org/ports/[the ports page] for info on software packages ported to FreeBSD.
 
 Most ports should work on all supported versions of FreeBSD. Those that do not are specifically marked as such. Each time a FreeBSD release is made, a snapshot of the ports tree at the time of release is also included in the [.filename]#ports/# directory.
 
 FreeBSD supports compressed binary packages to easily install and uninstall ports. Use man:pkg[7] to control the installation of packages.
 
 [[how-do-download-ports-tree]]
 === How do I download the Ports tree? Should I be using Git?
 
 See crossref:handbook[ports-using-installation-methods,Installing the Ports Collection].
 
 [[ports-4x]]
 === Why can I not build this port on my {rel2-relx} -, or {rel-relx} -STABLE machine?
 
 If the installed FreeBSD version lags significantly behind _-CURRENT_ or _-STABLE_, update the Ports Collection using the instructions in link:{handbook}#ports-using/[Using the Ports Collection]. If the system is up-to-date, someone might have committed a change to the port which works for _-CURRENT_ but which broke the port for _-STABLE_. https://bugs.FreeBSD.org/submit/[Submit] a bug report, since the Ports Collection is supposed to work for both the _-CURRENT_ and _-STABLE_ branches.
 
 [[make-index]]
 === I just tried to build INDEX using make index, and it failed. Why?
 
 First, make sure that the Ports Collection is up-to-date. Errors that affect building [.filename]#INDEX# from an up-to-date copy of the Ports Collection are high-visibility and are thus almost always fixed immediately.
 
 There are rare cases where [.filename]#INDEX# will not build due to odd cases involving `OPTIONS_SET` being set in [.filename]#make.conf#. If you suspect that this is the case, try to make [.filename]#INDEX# with those variables turned off before reporting it to {freebsd-ports}.
 
 [[ports-update]]
 === I updated the sources, now how do I update my installed ports?
 
 FreeBSD does not include a port upgrading tool, but it does have some tools to make the upgrade process somewhat easier. Additional tools are available to simplify port handling and are described the link:{handbook}#ports-using/[Upgrading Ports] section in the FreeBSD Handbook.
 
 [[ports-major-upgrade]]
 === Do I need to recompile every port each time I perform a major version update?
 
 Yes! While a recent system will run with software compiled under an older release, things will randomly crash and fail to work once other ports are installed or updated.
 
 When the system is upgraded, various shared libraries, loadable modules, and other parts of the system will be replaced with newer versions. Applications linked against the older versions may fail to start or, in other cases, fail to function properly.
 
 For more information, see link:{handbook}#freebsdupdate-upgrade[the section on upgrades] in the FreeBSD Handbook.
 
 [[ports-minor-upgrade]]
 === Do I need to recompile every port each time I perform a minor version update?
 
 In general, no. FreeBSD developers do their utmost to guarantee binary compatibility across all releases with the same major version number. Any exceptions will be documented in the Release Notes, and advice given there should be followed.
 
 [[minimal-sh]]
 === Why is /bin/sh so minimal? Why does FreeBSD not use bash or another shell?
 
 Many people need to write shell scripts which will be portable across many systems. That is why POSIX(R) specifies the shell and utility commands in great detail. Most scripts are written in Bourne shell (man:sh[1]), and because several important programming interfaces (man:make[1], man:system[3], man:popen[3], and analogues in higher-level scripting languages like Perl and Tcl) are specified to use the Bourne shell to interpret commands. As the Bourne shell is so often and widely used, it is important for it to be quick to start, be deterministic in its behavior, and have a small memory footprint.
 
 The existing implementation is our best effort at meeting as many of these requirements simultaneously as we can. To keep `/bin/sh` small, we have not provided many of the convenience features that other shells have. That is why other more featureful shells like `bash`, `scsh`, man:tcsh[1], and `zsh` are available. Compare the memory utilization of these shells by looking at the "VSZ" and "RSS" columns in a `ps -u` listing.
 
 [[kernelconfig]]
 == Kernel Configuration
 
 [[make-kernel]]
 === I would like to customize my kernel. Is it difficult?
 
 Not at all! Check out the link:{handbook}#kernelconfig/[kernel config section of the Handbook].
 
 [NOTE]
 ====
 The new [.filename]#kernel# will be installed to the [.filename]#/boot/kernel# directory along with its modules, while the old kernel and its modules will be moved to the [.filename]#/boot/kernel.old# directory. If a mistake is made in the configuration, simply boot the previous version of the kernel.
 ====
 
 [[why-kernel-big]]
 === Why is my kernel so big?
 
 `GENERIC` kernels shipped with FreeBSD are compiled in _debug mode_. Kernels built in debug mode contain debug data in separate files that are used for debugging. FreeBSD releases prior to 11.0 store these debug files in the same directory as the kernel itself, [.filename]#/boot/kernel/#. In FreeBSD 11.0 and later the debug files are stored in [.filename]#/usr/lib/debug/boot/kernel/#. Note that there will be little or no performance loss from running a debug kernel, and it is useful to keep one around in case of a system panic.
 
 When running low on disk space, there are different options to reduce the size of [.filename]#/boot/kernel/# and [.filename]#/usr/lib/debug/#.
 
 To not install the symbol files, make sure the following line exists in [.filename]#/etc/src.conf#:
 
 [.programlisting]
 ....
 WITHOUT_KERNEL_SYMBOLS=yes
 ....
 
 For more information see man:src.conf[5].
 
 If you want to avoid building debug files altogether, make sure that both of the following are true:
 
 * This line does not exist in the kernel configuration file:
 +
 [.programlisting]
 ....
 makeoptions DEBUG=-g
 ....
 
 * Do not run man:config[8] with `-g`.
 
 Either of the above settings will cause the kernel to be built in debug mode.
 
 To build and install only the specified modules, list them in [.filename]#/etc/make.conf#:
 
 [.programlisting]
 ....
 MODULES_OVERRIDE= accf_http ipfw
 ....
 
 Replace _accf_httpd ipfw_ with a list of needed modules. Only the listed modules will be built. This reduces the size of the kernel directory and decreases the amount of time needed to build the kernel. For more information, read [.filename]#/usr/share/examples/etc/make.conf#.
 
 Unneeded devices can be removed from the kernel to further reduce the size. See <<make-kernel>> for more information.
 
 To put any of these options into effect, follow the instructions to link:{handbook}#kernelconfig-building/[build and install] the new kernel.
 
 For reference, the FreeBSD 11 amd64 kernel ([.filename]#/boot/kernel/kernel#) is approximately 25 MB.
 
 [[generic-kernel-build-failure]]
 === Why does every kernel I try to build fail to compile, even GENERIC?
 
 There are a number of possible causes for this problem:
 
 * The source tree is different from the one used to build the currently running system. When attempting an upgrade, read [.filename]#/usr/src/UPDATING#, paying particular attention to the "COMMON ITEMS" section at the end.
 * The `make buildkernel` did not complete successfully. The `make buildkernel` target relies on files generated by the `make buildworld` target to complete its job correctly.
 * Even when building <<stable,FreeBSD-STABLE>>, it is possible that the source tree was fetched at a time when it was either being modified or it was broken. Only releases are guaranteed to be buildable, although <<stable,FreeBSD-STABLE>> builds fine the majority of the time. Try re-fetching the source tree and see if the problem goes away. Try using a different mirror in case the previous one is having problems.
 
 [[scheduler-in-use]]
 === Which scheduler is in use on a running system?
 
 The name of the scheduler currently being used is directly available as the value of the `kern.sched.name` sysctl:
 
 [source,shell]
 ....
 % sysctl kern.sched.name
 kern.sched.name: ULE
 ....
 
 [[scheduler-kern-quantum]]
 === What is kern.sched.quantum?
 
 `kern.sched.quantum` is the maximum number of ticks a process can run without being preempted in the 4BSD scheduler.
 
 [[disks]]
 == Disks, File Systems, and Boot Loaders
 
 [[adding-disks]]
 === How can I add my new hard disk to my FreeBSD system?
 
 See the link:{handbook}#disks-adding/[Adding Disks] section in the FreeBSD Handbook.
 
 [[new-huge-disk]]
 === How do I move my system over to my huge new disk?
 
 The best way is to reinstall the operating system on the new disk, then move the user data over. This is highly recommended when tracking _-STABLE_ for more than one release or when updating a release instead of installing a new one. Install booteasy on both disks with man:boot0cfg[8] and dual boot until you are happy with the new configuration. Skip the next paragraph to find out how to move the data after doing this.
 
 Alternatively, partition and label the new disk with either man:sade[8] or man:gpart[8]. If the disks are MBR-formatted, booteasy can be installed on both disks with man:boot0cfg[8] so that the computer can dual boot to the old or new system after the copying is done.
 
 Once the new disk set up, the data cannot just be copied. Instead, use tools that understand device files and system flags, such as man:dump[8]. Although it is recommended to move the data while in single-user mode, it is not required.
 
 When the disks are formatted with UFS, never use anything but man:dump[8] and man:restore[8] to move the root file system. These commands should also be used when moving a single partition to another empty partition. The sequence of steps to use `dump` to move the data from one UFS partitions to a new partition is:
 
 [.procedure]
 ====
 . `newfs` the new partition.
 . `mount` it on a temporary mount point.
 . `cd` to that directory.
 . `dump` the old partition, piping output to the new one.
 ====
 
 For example, to move [.filename]#/dev/ada1s1a# with [.filename]#/mnt# as the temporary mount point, type:
 
 [source,shell]
 ....
 # newfs /dev/ada1s1a
 # mount /dev/ada1s1a /mnt
 # cd /mnt
 # dump 0af - / | restore rf -
 ....
 
 Rearranging partitions with `dump` takes a bit more work. To merge a partition like [.filename]#/var# into its parent, create the new partition large enough for both, move the parent partition as described above, then move the child partition into the empty directory that the first move created:
 
 [source,shell]
 ....
 # newfs /dev/ada1s1a
 # mount /dev/ada1s1a /mnt
 # cd /mnt
 # dump 0af - / | restore rf -
 # cd var
 # dump 0af - /var | restore rf -
 ....
 
 To split a directory from its parent, say putting [.filename]#/var# on its own partition when it was not before, create both partitions, then mount the child partition on the appropriate directory in the temporary mount point, then move the old single partition:
 
 [source,shell]
 ....
 # newfs /dev/ada1s1a
 # newfs /dev/ada1s1d
 # mount /dev/ada1s1a /mnt
 # mkdir /mnt/var
 # mount /dev/ada1s1d /mnt/var
 # cd /mnt
 # dump 0af - / | restore rf -
 ....
 
 The man:cpio[1] and man:pax[1] utilities are also available for moving user data. These are known to lose file flag information, so use them with caution.
 
 [[safe-softupdates]]
 === Which partitions can safely use Soft Updates? I have heard that Soft Updates on / can cause problems. What about Journaled Soft Updates?
 
 Short answer: Soft Updates can usually be safely used on all partitions.
 
 Long answer: Soft Updates has two characteristics that may be undesirable on certain partitions. First, a Soft Updates partition has a small chance of losing data during a system crash. The partition will not be corrupted as the data will simply be lost. Second, Soft Updates can cause temporary space shortages.
 
 When using Soft Updates, the kernel can take up to thirty seconds to write changes to the physical disk. When a large file is deleted the file still resides on disk until the kernel actually performs the deletion. This can cause a very simple race condition. Suppose one large file is deleted and another large file is immediately created. The first large file is not yet actually removed from the physical disk, so the disk might not have enough room for the second large file. This will produce an error that the partition does not have enough space, even though a large chunk of space has just been released. A few seconds later, the file creation works as expected.
 
 If a system should crash after the kernel accepts a chunk of data for writing to disk, but before that data is actually written out, data could be lost. This risk is extremely small, but generally manageable.
 
 These issues affect all partitions using Soft Updates. So, what does this mean for the root partition?
 
 Vital information on the root partition changes very rarely. If the system crashed during the thirty-second window after such a change is made, it is possible that data could be lost. This risk is negligible for most applications, but be aware that it exists. If the system cannot tolerate this much risk, do not use Soft Updates on the root file system!
 
 [.filename]#/# is traditionally one of the smallest partitions. If [.filename]#/tmp# is on [.filename]#/#, there may be intermittent space problems. Symlinking [.filename]#/tmp# to [.filename]#/var/tmp# will solve this problem.
 
 Finally, man:dump[8] does not work in live mode (-L) on a filesystem, with Journaled Soft Updates (SU+J).
 
 [[mount-foreign-fs]]
 === Can I mount other foreign file systems under FreeBSD?
 
 FreeBSD supports a variety of other file systems.
 
 UFS::
 UFS CD-ROMs can be mounted directly on FreeBSD. Mounting disk partitions from Digital UNIX and other systems that support UFS may be more complex, depending on the details of the disk partitioning for the operating system in question.
 
 ext2/ext3::
 FreeBSD supports `ext2fs`, `ext3fs`, and `ext4fs` partitions. See man:ext2fs[5] for more information.
 
 NTFS::
 FUSE based NTFS support is available as a port (package:sysutils/fusefs-ntfs[]). For more information, see man:ntfs-3g[8].
 
 FAT::
 FreeBSD includes a read-write FAT driver. For more information, see man:mount_msdosfs[8].
 
 ZFS::
 FreeBSD includes a port of Sun(TM)'s ZFS driver. The current recommendation is to use it only on amd64 platforms with sufficient memory. For more information, see man:zfs[8].
 
 FreeBSD includes the Network File System NFS and the FreeBSD Ports Collection provides several FUSE applications to support many other file systems.
 
 [[mount-dos]]
 === How do I mount a secondary DOS partition?
 
 The secondary DOS partitions are found after _all_ the primary partitions. For example, if `E` is the second DOS partition on the second SCSI drive, there will be a device file for "slice 5" in [.filename]#/dev#. To mount it:
 
 [source,shell]
 ....
 # mount -t msdosfs /dev/da1s5 /dos/e
 ....
 
 [[crypto-file-system]]
 === Is there a cryptographic file system for FreeBSD?
 
 Yes, man:gbde[8] and man:geli[8]. See the link:{handbook}#disks-encrypting/[Encrypting Disk Partitions] section of the FreeBSD Handbook.
 
 [[grub-loader]]
 === How do I boot FreeBSD and Linux(R) using GRUB?
 
 To boot FreeBSD using GRUB, add the following to either [.filename]#/boot/grub/menu.lst# or [.filename]#/boot/grub/grub.conf#, depending upon which is used by the Linux(R) distribution.
 
 [.programlisting]
 ....
 title FreeBSD 9.1
 	root (hd0,a)
 	kernel /boot/loader
 ....
 
 Where _hd0,a_ points to the root partition on the first disk. To specify the slice number, use something like this _(hd0,2,a)_. By default, if the slice number is omitted, GRUB searches the first slice which has the `a` partition.
 
 [[booteasy-loader]]
 === How do I boot FreeBSD and Linux(R) using BootEasy?
 
 Install LILO at the start of the Linux(R) boot partition instead of in the Master Boot Record. Then boot LILO from BootEasy.
 
 This is recommended when running Windows(R) and Linux(R) as it makes it simpler to get Linux(R) booting again if Windows(R) is reinstalled.
 
 [[changing-bootprompt]]
 === How do I change the boot prompt from ??? to something more meaningful?
 
 This cannot be accomplished with the standard boot manager without rewriting it. There are a number of other boot managers in the [.filename]#sysutils# category of the Ports Collection.
 
 [[removable-drives]]
 === How do I use a new removable drive?
 
 If the drive already has a file system on it, use a command like this:
 
 [source,shell]
 ....
 # mount -t msdosfs /dev/da0s1 /mnt
 ....
 
 If the drive will only be used with FreeBSD systems, partition it with UFS or ZFS. This will provide long filename support, improvement in performance, and stability. If the drive will be used by other operating systems, a more portable choice, such as msdosfs, is better.
 
 [source,shell]
 ....
 # dd if=/dev/zero of=/dev/da0 count=2
 # gpart create -s GPT /dev/da0
 # gpart add -t freebsd-ufs /dev/da0
 ....
 
 Finally, create a new file system:
 
 [source,shell]
 ....
 # newfs /dev/da0p1
 ....
 
 and mount it:
 
 [source,shell]
 ....
 # mount /dev/da0s1 /mnt
 ....
 
 It is a good idea to add a line to [.filename]#/etc/fstab# (see man:fstab[5]) so you can just type `mount /mnt` in the future:
 
 [.programlisting]
 ....
 /dev/da0p1 /mnt ufs rw,noauto 0 0
 ....
 
 [[mount-cd-superblock]]
 === Why do I get Incorrect super block when mounting a CD?
 
 The type of device to mount must be specified. This is described in the Handbook section on link:{handbook}#mounting-cd[Using Data CDs].
 
 [[cdrom-not-configured]]
 === Why do I get Device not configured when mounting a CD?
 
 This generally means that there is no CD in the drive, or the drive is not visible on the bus. Refer to the link:{handbook}#mounting-cd[Using Data CDs] section of the Handbook for a detailed discussion of this issue.
 
 [[cdrom-unicode-filenames]]
 === Why do all non-English characters in filenames show up as ? on my CDs when mounted in FreeBSD?
 
 The CD probably uses the "Joliet" extension for storing information about files and directories. This is discussed in the Handbook section on link:{handbook}#mounting-cd[Using Data CD-ROMs].
 
 [[burncd-isofs]]
 === A CD burned under FreeBSD cannot be read under any other operating system. Why?
 
 This means a raw file was burned to the CD, rather than creating an ISO 9660 file system. Take a look at the Handbook section on link:{handbook}#mounting-cd[Using Data CDs].
 
 [[copy-cd]]
 === How can I create an image of a data CD?
 
 This is discussed in the Handbook section on link:{handbook}#mkisofs[Writing Data to an ISO File System]. For more on working with CD-ROMs, see the link:{handbook}#creating-cds/[Creating CDs Section] in the Storage chapter in the Handbook.
 
 [[mount-audio-CD]]
 === Why can I not mount an audio CD?
 
 Trying to mount an audio CD will produce an error like `cd9660: /dev/cd0: Invalid argument`. This is because `mount` only works on file systems. Audio CDs do not have file systems; they just have data. Instead, use a program that reads audio CDs, such as the package:audio/xmcd[] package or port.
 
 [[multi-session-CD]]
 === How do I mount a multi-session CD?
 
 By default, man:mount[8] will attempt to mount the last data track (session) of a CD. To load an earlier session, use the `-s` command line argument. Refer to man:mount_cd9660[8] for specific examples.
 
 [[user-floppymount]]
 === How do I let ordinary users mount CD-ROMs, DVDs, USB drives, and other removable media?
 
 As `root` set the sysctl variable `vfs.usermount` to `1`.
 
 [source,shell]
 ....
 # sysctl vfs.usermount=1
 ....
 
 To make this persist across reboots, add the line `vfs.usermount=1` to [.filename]#/etc/sysctl.conf# so that it is reset at system boot time.
 
 Users can only mount devices they have read permissions to. To allow users to mount a device permissions must be set in [.filename]#/etc/devfs.conf#.
 
 For example, to allow users to mount the first USB drive add:
 
 [.programlisting]
 ....
 # Allow all users to mount a USB drive.
 	    own       /dev/da0       root:operator
 	    perm      /dev/da0       0666
 ....
 
 All users can now mount devices they could read onto a directory that they own:
 
 [source,shell]
 ....
 % mkdir ~/my-mount-point
 % mount -t msdosfs /dev/da0 ~/my-mount-point
 ....
 
 Unmounting the device is simple:
 
 [source,shell]
 ....
 % umount ~/my-mount-point
 ....
 
 Enabling `vfs.usermount`, however, has negative security implications. A better way to access MS-DOS(R) formatted media is to use the package:emulators/mtools[] package in the Ports Collection.
 
 [NOTE]
 ====
 The device name used in the previous examples must be changed according to the configuration.
 ====
 
 [[du-vs-df]]
 === The du and df commands show different amounts of disk space available. What is going on?
 
 This is due to how these commands actually work. `du` goes through the directory tree, measures how large each file is, and presents the totals. `df` just asks the file system how much space it has left. They seem to be the same thing, but a file without a directory entry will affect `df` but not `du`.
 
 When a program is using a file, and the file is deleted, the file is not really removed from the file system until the program stops using it. The file is immediately deleted from the directory listing, however. As an example, consider a file large enough to affect the output of `du` and `df`. A file being viewed with `more` can be deleted without causing an error. The entry is removed from the directory so no other program or user can access it. However, `du` shows that it is gone as it has walked the directory tree and the file is not listed. `df` shows that it is still there, as the file system knows that `more` is still using that space. Once the `more` session ends, `du` and `df` will agree.
 
 This situation is common on web servers. Many people set up a FreeBSD web server and forget to rotate the log files. The access log fills up [.filename]#/var#. The new administrator deletes the file, but the system still complains that the partition is full. Stopping and restarting the web server program would free the file, allowing the system to release the disk space. To prevent this from happening, set up man:newsyslog[8].
 
 Note that Soft Updates can delay the freeing of disk space and it can take up to 30 seconds for the change to be visible.
 
 [[add-swap-space]]
 === How can I add more swap space?
 
 This section link:{handbook}#adding-swap-space/[of the Handbook] describes how to do this.
 
 [[manufacturer-disk-size]]
 === Why does FreeBSD see my disk as smaller than the manufacturer says it is?
 
 Disk manufacturers calculate gigabytes as a billion bytes each, whereas FreeBSD calculates them as 1,073,741,824 bytes each. This explains why, for example, FreeBSD's boot messages will report a disk that supposedly has 80 GB as holding 76,319 MB.
 
 Also note that FreeBSD will (by default) <<disk-more-than-full,reserve>> 8% of the disk space.
 
 [[disk-more-than-full]]
 === How is it possible for a partition to be more than 100% full?
 
 A portion of each UFS partition (8%, by default) is reserved for use by the operating system and the `root` user. man:df[1] does not count that space when calculating the `Capacity` column, so it can exceed 100%. Notice that the `Blocks` column is always greater than the sum of the `Used` and `Avail` columns, usually by a factor of 8%.
 
 For more details, look up `-m` in man:tunefs[8].
 
 [[all-about-zfs]]
 == ZFS
 
 [[how-much-ram-for-zfs]]
 === What is the minimum amount of RAM one should have to run ZFS?
 
 A minimum of 4GB of RAM is required for comfortable usage, but individual workloads can vary widely.
 
 [[what-is-zil]]
 === What is the ZIL and when does it get used?
 
 The ZIL (ZFS intent log) is a write log used to implement posix write commitment semantics across crashes. Normally writes are bundled up into transaction groups and written to disk when filled ("Transaction Group Commit"). However syscalls like man:fsync[2] require a commitment that the data is written to stable storage before returning. The ZIL is needed for writes that have been acknowledged as written but which are not yet on disk as part of a transaction. The transaction groups are timestamped. In the event of a crash the last valid timestamp is found and missing data is merged in from the ZIL.
 
 [[need-ssd-for-zil]]
 === Do I need a SSD for ZIL?
 
 By default, ZFS stores the ZIL in the pool with all the data. If an application has a heavy write load, storing the ZIL in a separate device that has very fast synchronous, sequential write performance can improve overall system performance. For other workloads, a SSD is unlikely to make much of an improvement.
 
 [[what-is-l2arc]]
 === What is the L2ARC?
 
 The L2ARC is a read cache stored on a fast device such as an SSD. This cache is not persistent across reboots. Note that RAM is used as the first layer of cache and the L2ARC is only needed if there is insufficient RAM.
 
 L2ARC needs space in the ARC to index it. So, perversely, a working set that fits perfectly in the ARC will not fit perfectly any more if a L2ARC is used because part of the ARC is holding the L2ARC index, pushing part of the working set into the L2ARC which is slower than RAM.
 
 [[should-enable-dedup]]
 === Is enabling deduplication advisable?
 
 Generally speaking, no.
 
 Deduplication takes up a significant amount of RAM and may slow down read and write disk access times. Unless one is storing data that is very heavily duplicated, such as virtual machine images or user backups, it is possible that deduplication will do more harm than good. Another consideration is the inability to revert deduplication status. If data is written when deduplication is enabled, disabling dedup will not cause those blocks which were deduplicated to be replicated until they are next modified.
 
 Deduplication can also lead to some unexpected situations. In particular, deleting files may become much slower.
 
 [[zpool-fully-full]]
 === I cannot delete or create files on my ZFS pool. How can I fix this?
 
 This could happen because the pool is 100% full. ZFS requires space on the disk to write transaction metadata. To restore the pool to a usable state, truncate the file to delete:
 
 [source,shell]
 ....
 % truncate -s 0 unimportant-file
 ....
 
 File truncation works because a new transaction is not started, new spare blocks are created instead.
 
 [NOTE]
 ====
 On systems with additional ZFS dataset tuning, such as deduplication, the space may not be immediately available
 ====
 
 [[zfs-ssd-trim]]
 === Does ZFS support TRIM for Solid State Drives?
 
 ZFS TRIM support was added to FreeBSD 10-CURRENT with revision link:https://svnweb.freebsd.org/changeset/base/240868[r240868]. ZFS TRIM support was added to all FreeBSD-STABLE branches in link:https://svnweb.freebsd.org/changeset/base/252162[r252162] and link:https://svnweb.freebsd.org/changeset/base/251419[r251419], respectively.
 
 ZFS TRIM is enabled by default, and can be turned off by adding this line to [.filename]#/etc/sysctl.conf#:
 
 [.programlisting]
 ....
 vfs.zfs.trim.enabled=0
 ....
 
 [NOTE]
 ====
 ZFS TRIM support was added to GELI as of link:https://svnweb.freebsd.org/changeset/base/286444[r286444]. Please see man:geli[8] and the `-T` switch.
 ====
 
 [[admin]]
 == System Administration
 
 [[startup-config-files]]
 === Where are the system start-up configuration files?
 
 The primary configuration file is [.filename]#/etc/defaults/rc.conf# which is described in man:rc.conf[5]. System startup scripts such as [.filename]#/etc/rc# and [.filename]#/etc/rc.d#, which are described in man:rc[8], include this file. _Do not edit this file!_ Instead, to edit an entry in [.filename]#/etc/defaults/rc.conf#, copy the line into [.filename]#/etc/rc.conf# and change it there.
 
 For example, to start man:sshd[8], the included OpenSSH daemon:
 
 [source,shell]
 ....
 # echo 'sshd_enable="YES"' >> /etc/rc.conf
 ....
 
 Alternatively, use man:sysrc[8] to modify [.filename]#/etc/rc.conf#:
 
 [source,shell]
 ....
 # sysrc sshd_enable="YES"
 ....
 
 To start up local services, place shell scripts in the [.filename]#/usr/local/etc/rc.d# directory. These shell scripts should be set executable, the default file mode is `555`.
 
 [[adding-users]]
 === How do I add a user easily?
 
 Use the man:adduser[8] command, or the man:pw[8] command for more complicated situations.
 
 To remove the user, use the man:rmuser[8] command or, if necessary, man:pw[8].
 
 [[root-not-found-cron-errors]]
 === Why do I keep getting messages like root: not found after editing /etc/crontab?
 
 This is normally caused by editing the system crontab. This is not the correct way to do things as the system crontab has a different format to the per-user crontabs. The system crontab has an extra field, specifying which user to run the command as. man:cron[8] assumes this user is the first word of the command to execute. Since no such command exists, this error message is displayed.
 
 To delete the extra, incorrect crontab:
 
 [source,shell]
 ....
 # crontab -r
 ....
 
 [[su-wheel-group]]
 === Why do I get the error, you are not in the correct group to su root when I try to su to root?
 
 This is a security feature. In order to `su` to `root`, or any other account with superuser privileges, the user account must be a member of the `wheel` group. If this feature were not there, anybody with an account on a system who also found out ``root``'s password would be able to gain superuser level access to the system.
 
 To allow someone to `su` to `root`, put them in the `wheel` group using `pw`:
 
 [source,shell]
 ....
 # pw groupmod wheel -m lisa
 ....
 
 The above example will add user `lisa` to the group `wheel`.
 
 [[rcconf-readonly]]
 === I made a mistake in rc.conf, or another startup file, and now I cannot edit it because the file system is read-only. What should I do?
 
 Restart the system using `boot -s` at the loader prompt to enter single-user mode. When prompted for a shell pathname, press kbd:[Enter] and run `mount -urw /` to re-mount the root file system in read/write mode. You may also need to run `mount -a -t ufs` to mount the file system where your favorite editor is defined. If that editor is on a network file system, either configure the network manually before mounting the network file systems, or use an editor which resides on a local file system, such as man:ed[1].
 
 In order to use a full screen editor such as man:vi[1] or man:emacs[1], run `export TERM=xterm` so that these editors can load the correct data from the man:termcap[5] database.
 
 After performing these steps, edit [.filename]#/etc/rc.conf# to fix the syntax error. The error message displayed immediately after the kernel boot messages should indicate the number of the line in the file which is at fault.
 
 [[printer-setup]]
 === Why am I having trouble setting up my printer?
 
 See the link:{handbook}#printing/[Handbook entry on printing] for troubleshooting tips.
 
 [[keyboard-mappings]]
 === How can I correct the keyboard mappings for my system?
 
 Refer to the Handbook section on link:{handbook}#using-localization/[using localization], specifically the section on link:{handbook}#setting-console[console setup].
 
 [[user-quotas]]
 === Why can I not get user quotas to work properly?
 
 . It is possible that the kernel is not configured to use quotas. In this case, add the following line to the kernel configuration file and recompile the kernel:
 +
 [.programlisting]
 ....
 options QUOTA
 ....
-+ 
++
 Refer to the link:{handbook}#quotas/[Handbook entry on quotas] for full details.
 . Do not turn on quotas on [.filename]#/#.
 . Put the quota file on the file system that the quotas are to be enforced on:
 +
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | File System
 | Quota file
 
 |[.filename]#/usr#
 |[.filename]#/usr/admin/quotas#
 
 |[.filename]#/home#
 |[.filename]#/home/admin/quotas#
 
 |...
 |...
 |===
 
 [[sysv-ipc]]
 === Does FreeBSD support System V IPC primitives?
 
 Yes, FreeBSD supports System V-style IPC, including shared memory, messages and semaphores, in the [.filename]#GENERIC# kernel. With a custom kernel, support may be loaded with the [.filename]#sysvshm.ko#, [.filename]#sysvsem.ko# and [.filename]#sysvmsg.ko# kernel modules, or enabled in the custom kernel by adding the following lines to the kernel configuration file:
 
 [.programlisting]
 ....
 options    SYSVSHM          # enable shared memory
 options    SYSVSEM          # enable for semaphores
 options    SYSVMSG          # enable for messaging
 ....
 
 Recompile and install the kernel.
 
 [[sendmail-alternative]]
 === What other mail-server software can I use instead of Sendmail?
 
 The http://www.sendmail.org/[Sendmail] server is the default mail-server software for FreeBSD, but it can be replaced with another MTA installed from the Ports Collection. Available ports include package:mail/exim[], package:mail/postfix[], and package:mail/qmail[]. Search the mailing lists for discussions regarding the advantages and disadvantages of the available MTAs.
 
 [[forgot-root-pw]]
 === I have forgotten the root password! What do I do?
 
 Do not panic! Restart the system, type `boot -s` at the `Boot:` prompt to enter single-user mode. At the question about the shell to use, hit kbd:[Enter] which will display a # prompt. Enter `mount -urw /` to remount the root file system read/write, then run `mount -a` to remount all the file systems. Run `passwd root` to change the `root` password then run man:exit[1] to continue booting.
 
 [NOTE]
 ====
 If you are still prompted to give the `root` password when entering the single-user mode, it means that the console has been marked as `insecure` in [.filename]#/etc/ttys#. In this case, it will be required to boot from a FreeBSD installation disk, choose the [.guimenuitem]#Live CD# or [.guimenuitem]#Shell# at the beginning of the install process and issue the commands mentioned above. Mount the specific partition in this case and then chroot to it. For example, replace `mount -urw /` with `mount /dev/ada0p1 /mnt; chroot /mnt` for a system on _ada0p1_.
 ====
 
 [NOTE]
 ====
 If the root partition cannot be mounted from single-user mode, it is possible that the partitions are encrypted and it is impossible to mount them without the access keys. For more information see the section about encrypted disks in the FreeBSD link:{handbook}#disks-encrypting/[Handbook].
 ====
 
 [[CAD-reboot]]
 === How do I keep kbd:[Control] + kbd:[Alt] + kbd:[Delete] from rebooting the system?
 
 When using man:vt[4], the default console driver, this can be done by setting the following man:sysctl[8]:
 
 [source,shell]
 ....
 # sysctl kern.vt.kbd_reboot=0
 ....
 
 [[dos-to-unix-txt]]
 === How do I reformat DOS text files to UNIX(R) ones?
 
 Use this man:perl[1] command:
 
 [source,shell]
 ....
 % perl -i.bak -npe 's/\r\n/\n/g' file(s)
 ....
 
 where _file(s)_ is one or more files to process. The modification is done in-place, with the original file stored with a [.filename]#.bak# extension.
 
 Alternatively, use man:tr[1]:
 
 [source,shell]
 ....
 % tr -d '\r' < dos-text-file > unix-file
 ....
 
 _dos-text-file_ is the file containing DOS text while _unix-file_ will contain the converted output. This can be quite a bit faster than using `perl`.
 
 Yet another way to reformat DOS text files is to use the package:converters/dosunix[] port from the Ports Collection. Consult its documentation about the details.
 
 [[reread-rc]]
 === How do I re-read [.filename]#/etc/rc.conf# and re-start [.filename]#/etc/rc# without a reboot?
 
 Go into single-user mode and then back to multi-user mode:
 
 [source,shell]
 ....
 # shutdown now
 # return
 # exit
 ....
 
 [[release-candidate]]
 === I tried to update my system to the latest _-STABLE_, but got _-BETAx_, _-RC_ or __-PRERELEASE__! What is going on?
 
 Short answer: it is just a name. _RC_ stands for "Release Candidate". It signifies that a release is imminent. In FreeBSD, _-PRERELEASE_ is typically synonymous with the code freeze before a release. (For some releases, the _-BETA_ label was used in the same way as _-PRERELEASE_.)
 
 Long answer: FreeBSD derives its releases from one of two places. Major, dot-zero, releases, such as 9.0-RELEASE are branched from the head of the development stream, commonly referred to as <<current,-CURRENT>>. Minor releases, such as 6.3-RELEASE or 5.2-RELEASE, have been snapshots of the active <<stable,-STABLE>> branch. Starting with 4.3-RELEASE, each release also now has its own branch which can be tracked by people requiring an extremely conservative rate of development (typically only security advisories).
 
 When a release is about to be made, the branch from which it will be derived from has to undergo a certain process. Part of this process is a code freeze. When a code freeze is initiated, the name of the branch is changed to reflect that it is about to become a release. For example, if the branch used to be called 6.2-STABLE, its name will be changed to 6.3-PRERELEASE to signify the code freeze and signify that extra pre-release testing should be happening. Bug fixes can still be committed to be part of the release. When the source code is in shape for the release the name will be changed to 6.3-RC to signify that a release is about to be made from it. Once in the RC stage, only the most critical bugs found can be fixed. Once the release (6.3-RELEASE in this example) and release branch have been made, the branch will be renamed to 6.3-STABLE.
 
 For more information on version numbers and the various Subversion branches, refer to the link:{releng}[Release Engineering] article.
 
 [[kernel-chflag-failure]]
 === I tried to install a new kernel, and the man:chflags[1] failed. How do I get around this?
 
 Short answer: the security level is greater than 0. Reboot directly to single-user mode to install the kernel.
 
 Long answer: FreeBSD disallows changing system flags at security levels greater than 0. To check the current security level:
 
 [source,shell]
 ....
 # sysctl kern.securelevel
 ....
 
 The security level cannot be lowered in multi-user mode, so boot to single-user mode to install the kernel, or change the security level in [.filename]#/etc/rc.conf# then reboot. See the man:init[8] manual page for details on `securelevel`, and see [.filename]#/etc/defaults/rc.conf# and the man:rc.conf[5] manual page for more information on [.filename]#rc.conf#.
 
 [[kernel-securelevel-time]]
 === I cannot change the time on my system by more than one second! How do I get around this?
 
 Short answer: the system is at a security level greater than 1. Reboot directly to single-user mode to change the date.
 
 Long answer: FreeBSD disallows changing the time by more that one second at security levels greater than 1. To check the security level:
 
 [source,shell]
 ....
 # sysctl kern.securelevel
 ....
 
 The security level cannot be lowered in multi-user mode. Either boot to single-user mode to change the date or change the security level in [.filename]#/etc/rc.conf# and reboot. See the man:init[8] manual page for details on `securelevel`, and see [.filename]#/etc/defaults/rc.conf# and the man:rc.conf[5] manual page for more information on [.filename]#rc.conf#.
 
 [[statd-mem-leak]]
 === Why is rpc.statd using 256 MB of memory?
 
 No, there is no memory leak, and it is not using 256 MB of memory. For convenience, `rpc.statd` maps an obscene amount of memory into its address space. There is nothing terribly wrong with this from a technical standpoint; it just throws off things like man:top[1] and man:ps[1].
 
 man:rpc.statd[8] maps its status file (resident on [.filename]#/var#) into its address space; to save worrying about remapping the status file later when it needs to grow, it maps the status file with a generous size. This is very evident from the source code, where one can see that the length argument to man:mmap[2] is `0x10000000`, or one sixteenth of the address space on an IA32, or exactly 256 MB.
 
 [[unsetting-schg]]
 === Why can I not unset the schg file flag?
 
 The system is running at securelevel greater than 0. Lower the securelevel and try again. For more information, see <<securelevel,the FAQ entry on securelevel>> and the man:init[8] manual page.
 
 [[vnlru]]
 === What is vnlru?
 
 `vnlru` flushes and frees vnodes when the system hits the `kern.maxvnodes` limit. This kernel thread sits mostly idle, and only activates when there is a huge amount of RAM and users are accessing tens of thousands of tiny files.
 
 [[top-memory-states]]
 === What do the various memory states displayed by top mean?
 
 * `Active`: pages recently statistically used.
 * `Inactive`: pages recently statistically unused.
 * `Laundry`: pages recently statistically unused but known to be dirty, that is, whose contents needs to be paged out before they can be reused.
 * `Free`: pages without data content, which can be immediately reused.
 * `Wired`: pages that are fixed into memory, usually for kernel purposes, but also sometimes for special use in processes.
 
 Pages are most often written to disk (sort of a VM sync) when they are in the laundry state, but active or inactive pages can also be synced. This depends upon the CPU tracking of the modified bit being available, and in certain situations there can be an advantage for a block of VM pages to be synced, regardless of the queue they belong to. In most common cases, it is best to think of the laundry queue as a queue of relatively unused pages that might or might not be in the process of being written to disk. The inactive queue contains a mix of clean and dirty pages; clean pages near the head of the queue are reclaimed immediately to alleviate a free page shortage, and dirty pages are moved to the laundry queue for deferred processing.
 
 There are some other flags (e.g., busy flag or busy count) that might modify some of the described rules.
 
 [[free-memory-amount]]
 === How much free memory is available?
 
 There are a couple of kinds of "free memory". The most common is the amount of memory immediately available without reclaiming memory already in use. That is the size of the free pages queue plus some other reserved pages. This amount is exported by the `vm.stats.vm.v_free_count` man:sysctl[8], shown, for instance, by man:top[1]. Another kind of "free memory" is the total amount of virtual memory available to userland processes, which depends on the sum of swap space and usable memory. Other kinds of "free memory" descriptions are also possible, but it is relatively useless to define these, but rather it is important to make sure that the paging rate is kept low, and to avoid running out of swap space.
 
 [[var-empty]]
 === What is [.filename]#/var/empty#?
 
 [.filename]#/var/empty# is a directory that the man:sshd[8] program uses when performing privilege separation. The [.filename]#/var/empty# directory is empty, owned by `root` and has the `schg` flag set. This directory should not be deleted.
 
 [[newsyslog-expectations]]
 === I just changed [.filename]#/etc/newsyslog.conf#. How can I check if it does what I expect?
 
 To see what man:newsyslog[8] will do, use the following:
 
 [source,shell]
 ....
 % newsyslog -nrvv
 ....
 
 [[timezone]]
 === My time is wrong, how can I change the timezone?
 
 Use man:tzsetup[8].
 
 [[X11]]
 == The X Window System and Virtual Consoles
 
 [[whatis-X]]
 === What is the X Window System?
 
 The X Window System (commonly `X11`) is the most widely available windowing system capable of running on UNIX(R) or UNIX(R) like systems, including FreeBSD. http://www.x.org/wiki/[The X.Org Foundation] administers the http://en.wikipedia.org/wiki/X_Window_System_core_protocol[X protocol standards], with the current reference implementation, version 11 release 7.7, so references are often shortened to `X11`.
 
 Many implementations are available for different architectures and operating systems. An implementation of the server-side code is properly known as an `X server`.
 
 [[running-X]]
 === I want to run Xorg, how do I go about it?
 
 To install Xorg do one of the following:
 
 Use the package:x11/xorg[] meta-port, which builds and installs every Xorg component.
 
 Use package:x11/xorg-minimal[], which builds and installs only the necessary Xorg components.
 
 Install Xorg from FreeBSD packages:
 
 [source,shell]
 ....
 # pkg install xorg
 ....
 
 After the installation of Xorg, follow the instructions from the link:{handbook}#x-config/[X11 Configuration] section of the FreeBSD Handbook.
 
 [[running-X-securelevels]]
 === I tried to run X, but I get a No devices detected. error when I type startx. What do I do now?
 
 The system is probably running at a raised `securelevel`. It is not possible to start X at a raised `securelevel` because X requires write access to man:io[4]. For more information, see at the man:init[8] manual page.
 
 There are two solutions to the problem: set the `securelevel` back down to zero or run man:xdm[1] (or an alternative display manager) at boot time before the `securelevel` is raised.
 
 See <<xdm-boot>> for more information about running man:xdm[1] at boot time.
 
 [[x-and-moused]]
 === Why does my mouse not work with X?
 
 When using man:vt[4], the default console driver, FreeBSD can be configured to support a mouse pointer on each virtual screen. To avoid conflicting with X, man:vt[4] supports a virtual device called [.filename]#/dev/sysmouse#. All mouse events received from the real mouse device are written to the man:sysmouse[4] device via man:moused[8]. To use the mouse on one or more virtual consoles, _and_ use X, see <<moused>> and set up man:moused[8].
 
 Then edit [.filename]#/etc/X11/xorg.conf# and make sure the following lines exist:
 
 [.programlisting]
 ....
 Section "InputDevice"
    Option          "Protocol" "SysMouse"
    Option          "Device" "/dev/sysmouse"
 .....
 ....
 
 Starting with Xorg version 7.4, the `InputDevice` sections in [.filename]#xorg.conf# are ignored in favor of autodetected devices. To restore the old behavior, add the following line to the `ServerLayout` or `ServerFlags` section:
 
 [.programlisting]
 ....
 Option "AutoAddDevices" "false"
 ....
 
 Some people prefer to use [.filename]#/dev/mouse# under X. To make this work, [.filename]#/dev/mouse# should be linked to [.filename]#/dev/sysmouse# (see man:sysmouse[4]) by adding the following line to [.filename]#/etc/devfs.conf# (see man:devfs.conf[5]):
 
 [.programlisting]
 ....
 link    sysmouse    mouse
 ....
 
 This link can be created by restarting man:devfs[5] with the following command (as `root`):
 
 [source,shell]
 ....
 # service devfs restart
 ....
 
 [[x-and-wheel]]
 === My mouse has a fancy wheel. Can I use it in X?
 
 Yes, if X is configured for a 5 button mouse. To do this, add the lines `Buttons 5` and `ZAxisMapping 4 5` to the "InputDevice" section of [.filename]#/etc/X11/xorg.conf#, as seen in this example:
 
 [.programlisting]
 ....
 Section "InputDevice"
    Identifier      "Mouse1"
    Driver          "mouse"
    Option          "Protocol" "auto"
    Option          "Device" "/dev/sysmouse"
    Option          "Buttons" "5"
    Option          "ZAxisMapping" "4 5"
 EndSection
 ....
 
 The mouse can be enabled in Emacs by adding these lines to [.filename]#~/.emacs#:
 
 [.programlisting]
 ....
 ;; wheel mouse
 (global-set-key [mouse-4] 'scroll-down)
 (global-set-key [mouse-5] 'scroll-up)
 ....
 
 [[x-and-synaptic]]
 === My laptop has a Synaptics touchpad. Can I use it in X?
 
 Yes, after configuring a few things to make it work.
 
 In order to use the Xorg synaptics driver, first remove `moused_enable` from [.filename]#rc.conf#.
 
 To enable synaptics, add the following line to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 hw.psm.synaptics_support="1"
 ....
 
 Add the following to [.filename]#/etc/X11/xorg.conf#:
 
 [.programlisting]
 ....
 Section "InputDevice"
 Identifier  "Touchpad0"
 Driver      "synaptics"
 Option      "Protocol" "psm"
 Option      "Device" "/dev/psm0"
 EndSection
 ....
 
 And be sure to add the following into the "ServerLayout" section:
 
 [.programlisting]
 ....
 InputDevice    "Touchpad0" "SendCoreEvents"
 ....
 
 [[no-remote-x11]]
 === How do I use remote X displays?
 
 For security reasons, the default setting is to not allow a machine to remotely open a window.
 
 To enable this feature, start X with the optional `-listen_tcp` argument:
 
 [source,shell]
 ....
 % startx -listen_tcp
 ....
 
 [[virtual-console]]
 === What is a virtual console and how do I make more?
 
 Virtual consoles provide several simultaneous sessions on the same machine without doing anything complicated like setting up a network or running X.
 
 When the system starts, it will display a login prompt on the monitor after displaying all the boot messages. Type in your login name and password to start working on the first virtual console.
 
 To start another session, perhaps to look at documentation for a program or to read mail while waiting for an FTP transfer to finish, hold down kbd:[Alt] and press kbd:[F2]. This will display the login prompt for the second virtual console. To go back to the original session, press kbd:[Alt+F1].
 
 The default FreeBSD installation has eight virtual consoles enabled. kbd:[Alt+F1], kbd:[Alt+F2], kbd:[Alt+F3], and so on will switch between these virtual consoles.
 
 To enable more of virtual consoles, edit [.filename]#/etc/ttys# (see man:ttys[5]) and add entries for [.filename]#ttyv8# to [.filename]#ttyvc#, after the comment on "Virtual terminals":
 
 [.programlisting]
 ....
 # Edit the existing entry for ttyv8 in /etc/ttys and change
 # "off" to "on".
 ttyv8   "/usr/libexec/getty Pc"         xterm  on secure
 ttyv9   "/usr/libexec/getty Pc"         xterm  on secure
 ttyva   "/usr/libexec/getty Pc"         xterm  on secure
 ttyvb   "/usr/libexec/getty Pc"         xterm  on secure
 ....
 
 The more virtual terminals, the more resources that are used. This can be problematic on systems with 8 MB RAM or less. Consider changing `secure` to `insecure`.
 
 [IMPORTANT]
 ====
 In order to run an X server, at least one virtual terminal must be left to `off` for it to use. This means that only eleven of the Alt-function keys can be used as virtual consoles so that one is left for the X server.
 ====
 
 For example, to run X and eleven virtual consoles, the setting for virtual terminal 12 should be:
 
 [.programlisting]
 ....
 ttyvb   "/usr/libexec/getty Pc"         xterm  off secure
 ....
 
 The easiest way to activate the virtual consoles is to reboot.
 
 [[vty-from-x]]
 === How do I access the virtual consoles from X?
 
 Use kbd:[Ctrl+Alt+Fn] to switch back to a virtual console. Press kbd:[Ctrl+Alt+F1] to return to the first virtual console.
 
 Once at a text console, use kbd:[Alt+Fn] to move between them.
 
 To return to the X session, switch to the virtual console running X. If X was started from the command line using `startx`, the X session will attach to the next unused virtual console, not the text console from which it was invoked. For eight active virtual terminals, X will run on the ninth, so use kbd:[Alt+F9].
 
 [[xdm-boot]]
 === How do I start XDM on boot?
 
 There are two schools of thought on how to start man:xdm[1]. One school starts `xdm` from [.filename]#/etc/ttys# (see man:ttys[5]) using the supplied example, while the other sets `xdm_enable=yes` in [.filename]#/etc/rc.conf#. Both are equally valid, and one may work in situations where the other does not. In both cases the result is the same: X will pop up a graphical login prompt.
 
 The man:ttys[5] method has the advantage of documenting which vty X will start on and passing the responsibility of restarting the X server on logout to man:init[8]. The man:rc[8] method makes it easy to `kill xdm` if there is a problem starting the X server.
 
 When using the man:rc[8] method, `xdm_tty` (default `ttyv8`) can be set in [.filename]#/etc/rc.conf# to choose which vty man:xdm[1] opens on.
 
 [[xconsole-failure]]
 === Why do I get Couldn't open console when I run xconsole?
 
 When X is started with `startx`, the permissions on [.filename]#/dev/console# will _not_ get changed, resulting in things like `xterm -C` and `xconsole` not working.
 
 This is because of the way console permissions are set by default. On a multi-user system, one does not necessarily want just any user to be able to write on the system console. For users who are logging directly onto a machine with a VTY, the man:fbtab[5] file exists to solve such problems.
 
 In a nutshell, make sure an uncommented line of the form is in [.filename]#/etc/fbtab# (see man:fbtab[5]):
 
 [.programlisting]
 ....
 /dev/ttyv0 0600 /dev/console
 ....
 
 It will ensure that whomever logs in on [.filename]#/dev/ttyv0# will own the console.
 
 [[ps2-x]]
 === Why does my PS/2 mouse misbehave under X?
 
 The mouse and the mouse driver may have become out of synchronization. In rare cases, the driver may also erroneously report synchronization errors:
 
 [.programlisting]
 ....
 psmintr: out of sync (xxxx != yyyy)
 ....
 
 If this happens, disable the synchronization check code by setting the driver flags for the PS/2 mouse driver to `0x100`. This can be easiest achieved by adding `hint.psm.0.flags="0x100"` to [.filename]#/boot/loader.conf# and rebooting.
 
 [[mouse-button-reverse]]
 === How do I reverse the mouse buttons?
 
 Type `xmodmap -e "pointer = 3 2 1"`. Add this command to [.filename]#~/.xinitrc# or [.filename]#~/.xsession# to make it happen automatically.
 
 [[install-splash]]
 === How do I install a splash screen and where do I find them?
 
 The detailed answer for this question can be found in the link:{handbook}#boot-splash/[Boot Time Splash Screens] section of the FreeBSD Handbook.
 
 [[windows-keys]]
 === Can I use the kbd:[Windows] keys on my keyboard in X?
 
 Yes. Use man:xmodmap[1] to define which functions the keys should perform.
 
 Assuming all Windows keyboards are standard, the keycodes for these three keys are the following:
 
 * 115 - kbd:[Windows] key, between the left-hand kbd:[Ctrl] and kbd:[Alt] keys
 * 116 - kbd:[Windows] key, to the right of kbd:[AltGr]
 * 117 - kbd:[Menu], to the left of the right-hand kbd:[Ctrl]
 
 To have the left kbd:[Windows] key print a comma, try this.
 
 [source,shell]
 ....
 # xmodmap -e "keycode 115 = comma"
 ....
 
 To have the kbd:[Windows] key-mappings enabled automatically every time X is started, either put the `xmodmap` commands in [.filename]#~/.xinitrc# or, preferably, create a [.filename]#~/.xmodmaprc# and include the `xmodmap` options, one per line, then add the following line to [.filename]#~/.xinitrc#:
 
 [.programlisting]
 ....
 xmodmap $HOME/.xmodmaprc
 ....
 
 For example, to map the 3 keys to be kbd:[F13], kbd:[F14], and kbd:[F15], respectively. This would make it easy to map them to useful functions within applications or the window manager.
 
 To do this, put the following in [.filename]#~/.xmodmaprc#.
 
 [.programlisting]
 ....
 keycode 115 = F13
 keycode 116 = F14
 keycode 117 = F15
 ....
 
 For the package:x11-wm/fvwm2[] desktop manager, one could map the keys so that kbd:[F13] iconifies or de-iconifies the window the cursor is in, kbd:[F14] brings the window the cursor is in to the front or, if it is already at the front, pushes it to the back, and kbd:[F15] pops up the main Workplace menu even if the cursor is not on the desktop, which is useful when no part of the desktop is visible.
 
 The following entries in [.filename]#~/.fvwmrc# implement the aforementioned setup:
 
 [.programlisting]
 ....
 Key F13        FTIWS    A        Iconify
 Key F14        FTIWS    A        RaiseLower
 Key F15        A        A        Menu Workplace Nop
 ....
 
 [[x-3d-acceleration]]
 === How can I get 3D hardware acceleration for OpenGL(R)?
 
 The availability of 3D acceleration depends on the version of Xorg and the type of video chip. For an nVidia chip, use the binary drivers provided for FreeBSD by installing one of the following ports:
 
 The latest versions of nVidia cards are supported by the package:x11/nvidia-driver[] port.
 
 Older drivers are available as package:x11/nvidia-driver-[]
 
 nVidia provides detailed information on which card is supported by which driver on their web site: http://www.nvidia.com/object/IO_32667.html[http://www.nvidia.com/object/IO_32667.html].
 
 For Matrox G200/G400, check the package:x11-drivers/xf86-video-mga[] port.
 
 For ATI Rage 128 and Radeon see man:ati[4], man:r128[4] and man:radeon[4].
 
 [[networking]]
 == Networking
 
 [[diskless-booting]]
 === Where can I get information on diskless booting?
 
 "Diskless booting" means that the FreeBSD box is booted over a network, and reads the necessary files from a server instead of its hard disk. For full details, see link:{handbook}#network-diskless/[the Handbook entry on diskless booting].
 
 [[router]]
 === Can a FreeBSD box be used as a dedicated network router?
 
 Yes. Refer to the Handbook entry on link:{handbook}#advanced-networking/[advanced networking], specifically the section on link:{handbook}#network-routing/[routing and gateways].
 
 [[natd]]
 === Does FreeBSD support NAT or Masquerading?
 
 Yes. For instructions on how to use NAT over a PPP connection, see the link:{handbook}#userppp/[Handbook entry on PPP]. To use NAT over some other sort of network connection, look at the link:{handbook}#network-natd[natd] section of the Handbook.
 
 [[ethernet-aliases]]
 === How can I set up Ethernet aliases?
 
 If the alias is on the same subnet as an address already configured on the interface, add `netmask 0xffffffff` to this command:
 
 [source,shell]
 ....
 # ifconfig ed0 alias 192.0.2.2 netmask 0xffffffff
 ....
 
 Otherwise, specify the network address and netmask as usual:
 
 [source,shell]
 ....
 # ifconfig ed0 alias 172.16.141.5 netmask 0xffffff00
 ....
 
 More information can be found in the FreeBSD link:{handbook}#configtuning-virtual-hosts/[Handbook].
 
 [[nfs-linux]]
 === Why can I not NFS-mount from a Linux(R) box?
 
 Some versions of the Linux(R) NFS code only accept mount requests from a privileged port; try to issue the following command:
 
 [source,shell]
 ....
 # mount -o -P linuxbox:/blah /mnt
 ....
 
 [[exports-errors]]
 === Why does mountd keep telling me it can't change attributes and that I have a bad exports list on my FreeBSD NFS server?
 
 The most frequent problem is not understanding the correct format of [.filename]#/etc/exports#. Review man:exports[5] and the link:{handbook}#network-nfs/[NFS] entry in the Handbook, especially the section on link:{handbook}#configuring-nfs[configuring NFS].
 
 [[ip-multicast]]
 === How do I enable IP multicast support?
 
 Install the package:net/mrouted[] package or port and add `mrouted_enable="YES"` to [.filename]#/etc/rc.conf# start this service at boot time.
 
 [[fqdn-hosts]]
 === Why do I have to use the FQDN for hosts on my site?
 
 See the answer in the FreeBSD link:{handbook}#mail-trouble/[Handbook].
 
 [[network-permission-denied]]
 === Why do I get an error, Permission denied, for all networking operations?
 
 If the kernel is compiled with the `IPFIREWALL` option, be aware that the default policy is to deny all packets that are not explicitly allowed.
 
 If the firewall is unintentionally misconfigured, restore network operability by typing the following as `root`:
 
 [source,shell]
 ....
 # ipfw add 65534 allow all from any to any
 ....
 
 Consider setting `firewall_type="open"` in [.filename]#/etc/rc.conf#.
 
 For further information on configuring this firewall, see the link:{handbook}#firewalls-ipfw/[Handbook chapter].
 
 [[ipfw-fwd]]
 === Why is my `ipfw` “fwd” rule to redirect a service to another machine not working?
 
 Possibly because network address translation (NAT) is needed instead of just forwarding packets. A "fwd" rule only forwards packets, it does not actually change the data inside the packet. Consider this rule:
 
 [source,shell]
 ....
 01000 fwd 10.0.0.1 from any to foo 21
 ....
 
 When a packet with a destination address of _foo_ arrives at the machine with this rule, the packet is forwarded to _10.0.0.1_, but it still has the destination address of _foo_. The destination address of the packet is not changed to _10.0.0.1_. Most machines would probably drop a packet that they receive with a destination address that is not their own. Therefore, using a "fwd" rule does not often work the way the user expects. This behavior is a feature and not a bug.
 
 See the <<service-redirect,FAQ about redirecting services>>, the man:natd[8] manual, or one of the several port redirecting utilities in the link:https://www.FreeBSD.org/ports/[Ports Collection] for a correct way to do this.
 
 [[service-redirect]]
 === How can I redirect service requests from one machine to another?
 
 FTP and other service requests can be redirected with the package:sysutils/socket[] package or port. Replace the entry for the service in [.filename]#/etc/inetd.conf# to call `socket`, as seen in this example for ftpd:
 
 [.programlisting]
 ....
 ftp stream tcp nowait nobody /usr/local/bin/socket socket ftp.example.com ftp
 ....
 
 where _ftp.example.com_ and _ftp_ are the host and port to redirect to, respectively.
 
 [[bandwidth-mgr-tool]]
 === Where can I get a bandwidth management tool?
 
 There are three bandwidth management tools available for FreeBSD. man:dummynet[4] is integrated into FreeBSD as part of man:ipfw[4]. http://www.sonycsl.co.jp/person/kjc/programs.html[ALTQ] has been integrated into FreeBSD as part of man:pf[4]. Bandwidth Manager from http://www.etinc.com/[Emerging Technologies] is a commercial product.
 
 [[bpf-not-configured]]
 === Why do I get /dev/bpf0: device not configured?
 
 The running application requires the Berkeley Packet Filter (man:bpf[4]), but it was removed from a custom kernel. Add this to the kernel config file and build a new kernel:
 
 [.programlisting]
 ....
 device bpf        # Berkeley Packet Filter
 ....
 
 [[mount-smb-share]]
 === How do I mount a disk from a Windows(R) machine that is on my network, like smbmount in Linux(R)?
 
 Use the SMBFS toolset. It includes a set of kernel modifications and a set of userland programs. The programs and information are available as man:mount_smbfs[8] in the base system.
 
 [[icmp-response-bw-limit]]
 === What are these messages about: Limiting icmp/open port/closed port response in my log files?
 
 This kernel message indicates that some activity is provoking it to send a large amount of ICMP or TCP reset (RST) responses. ICMP responses are often generated as a result of attempted connections to unused UDP ports. TCP resets are generated as a result of attempted connections to unopened TCP ports. Among others, these are the kinds of activities which may cause these messages:
 
 * Brute-force denial of service (DoS) attacks (as opposed to single-packet attacks which exploit a specific vulnerability).
 * Port scans which attempt to connect to a large number of ports (as opposed to only trying a few well-known ports).
 
 The first number in the message indicates how many packets the kernel would have sent if the limit was not in place, and the second indicates the limit. This limit is controlled using `net.inet.icmp.icmplim`. This example sets the limit to `300` packets per second:
 
 [source,shell]
 ....
 # sysctl net.inet.icmp.icmplim=300
 ....
 
 To disable these messages without disabling response limiting, use `net.inet.icmp.icmplim_output` to disable the output:
 
 [source,shell]
 ....
 # sysctl net.inet.icmp.icmplim_output=0
 ....
 
 Finally, to disable response limiting completely, set `net.inet.icmp.icmplim` to `0`. Disabling response limiting is discouraged for the reasons listed above.
 
 [[unknown-hw-addr-format]]
 === What are these arp: unknown hardware address format error messages?
 
 This means that some device on the local Ethernet is using a MAC address in a format that FreeBSD does not recognize. This is probably caused by someone experimenting with an Ethernet card somewhere else on the network. This is most commonly seen on cable modem networks. It is harmless, and should not affect the performance of the FreeBSD system.
 
 [[arp-wrong-iface]]
 === Why do I keep seeing messages like: 192.168.0.10 is on fxp1 but got reply from 00:15:17:67:cf:82 on rl0, and how do I disable it?
 
 A packet is coming from outside the network unexpectedly. To disable them, set `net.link.ether.inet.log_arp_wrong_iface` to `0`.
 
 [[ipv6-only]]
 === How do I compile an IPv6 only kernel?
 
 Configure your kernel with these settings: 
 
 [source,shell]
 ....
 include GENERIC
 ident GENERIC-IPV6ONLY
 makeoptions MKMODULESENV+="WITHOUT_INET_SUPPORT="
 nooptions INET
 nodevice gre
 ....
 
 [[security]]
 == Security
 
 [[sandbox]]
 === What is a sandbox?
 
 "Sandbox" is a security term. It can mean two things:
 
 * A process which is placed inside a set of virtual walls that are designed to prevent someone who breaks into the process from being able to break into the wider system.
-+ 
++
 The process is only able to run inside the walls. Since nothing the process does in regards to executing code is supposed to be able to breach the walls, a detailed audit of its code is not needed in order to be able to say certain things about its security.
-+ 
++
 The walls might be a user ID, for example. This is the definition used in the man:security[7] and man:named[8] man pages.
-+ 
++
 Take the `ntalk` service, for example (see man:inetd[8]). This service used to run as user ID `root`. Now it runs as user ID `tty`. The `tty` user is a sandbox designed to make it more difficult for someone who has successfully hacked into the system via `ntalk` from being able to hack beyond that user ID.
 * A process which is placed inside a simulation of the machine. It means that someone who is able to break into the process may believe that he can break into the wider machine but is, in fact, only breaking into a simulation of that machine and not modifying any real data.
-+ 
++
 The most common way to accomplish this is to build a simulated environment in a subdirectory and then run the processes in that directory chrooted so that [.filename]#/# for that process is this directory, not the real [.filename]#/# of the system).
-+ 
++
 Another common use is to mount an underlying file system read-only and then create a file system layer on top of it that gives a process a seemingly writeable view into that file system. The process may believe it is able to write to those files, but only the process sees the effects - other processes in the system do not, necessarily.
-+ 
++
 An attempt is made to make this sort of sandbox so transparent that the user (or hacker) does not realize that he is sitting in it.
 
 UNIX(R) implements two core sandboxes. One is at the process level, and one is at the userid level.
 
 Every UNIX(R) process is completely firewalled off from every other UNIX(R) process. One process cannot modify the address space of another.
 
 A UNIX(R) process is owned by a particular userid. If the user ID is not the `root` user, it serves to firewall the process off from processes owned by other users. The user ID is also used to firewall off on-disk data.
 
 [[securelevel]]
 === What is securelevel?
 
 `securelevel` is a security mechanism implemented in the kernel. When the securelevel is positive, the kernel restricts certain tasks; not even the superuser (`root`) is allowed to do them. The securelevel mechanism limits the ability to:
 
 * Unset certain file flags, such as `schg` (the system immutable flag).
 * Write to kernel memory via [.filename]#/dev/mem# and [.filename]#/dev/kmem#.
 * Load kernel modules.
 * Alter firewall rules.
 
 To check the status of the securelevel on a running system:
 
 [source,shell]
 ....
 # sysctl -n kern.securelevel
 ....
 
 The output contains the current value of the securelevel. If it is greater than 0, at least some of the securelevel's protections are enabled.
 
 The securelevel of a running system cannot be lowered as this would defeat its purpose. If a task requires that the securelevel be non-positive, change the `kern_securelevel` and `kern_securelevel_enable` variables in [.filename]#/etc/rc.conf# and reboot.
 
 For more information on securelevel and the specific things all the levels do, consult man:init[8].
 
 [WARNING]
 ====
 
 Securelevel is not a silver bullet; it has many known deficiencies. More often than not, it provides a false sense of security.
 
 One of its biggest problems is that in order for it to be at all effective, all files used in the boot process up until the securelevel is set must be protected. If an attacker can get the system to execute their code prior to the securelevel being set (which happens quite late in the boot process since some things the system must do at start-up cannot be done at an elevated securelevel), its protections are invalidated. While this task of protecting all files used in the boot process is not technically impossible, if it is achieved, system maintenance will become a nightmare since one would have to take the system down, at least to single-user mode, to modify a configuration file.
 
 This point and others are often discussed on the mailing lists, particularly the {freebsd-security}. Search the archives link:https://www.FreeBSD.org/search/[here] for an extensive discussion. A more fine-grained mechanism is preferred.
 ====
 
 [[toor-account]]
 === What is this UID 0 toor account? Have I been compromised?
 
 Do not worry. `toor` is an "alternative" superuser account, where toor is root spelled backwards. It is intended to be used with a non-standard shell so the default shell for `root` does not need to change. This is important as shells which are not part of the base distribution, but are instead installed from ports or packages, are installed in [.filename]#/usr/local/bin# which, by default, resides on a different file system. If ``root``'s shell is located in [.filename]#/usr/local/bin# and the file system containing [.filename]#/usr/local/bin#) is not mounted, `root` will not be able to log in to fix a problem and will have to reboot into single-user mode in order to enter the path to a shell.
 
 Some people use `toor` for day-to-day `root` tasks with a non-standard shell, leaving `root`, with a standard shell, for single-user mode or emergencies. By default, a user cannot log in using `toor` as it does not have a password, so log in as `root` and set a password for `toor` before using it to login.
 
 [[serial]]
 == Serial Communications
 
 This section answers common questions about serial communications with FreeBSD.
 
 [[serial-console-prompt]]
 === How do I get the boot: prompt to show on the serial console?
 
 See link:{handbook}#serialconsole-setup/[this section of the Handbook].
 
 [[found-serial]]
 === How do I tell if FreeBSD found my serial ports or modem cards?
 
 As the FreeBSD kernel boots, it will probe for the serial ports for which the kernel is configured. Either watch the boot messages closely or run this command after the system is up and running:
 
 [source,shell]
 ....
 % grep -E '^(sio|uart)[0-9]' < /var/run/dmesg.boot
 sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
 sio0: type 16550A
 sio1: <16550A-compatible COM port> port 0x2f8-0x2ff irq 3 on acpi0
 sio1: type 16550A
 ....
 
 This example shows two serial ports. The first is on IRQ4, port address `0x3f8`, and has a 16550A-type UART chip. The second uses the same kind of chip but is on IRQ3 and is at port address `0x2f8`. Internal modem cards are treated just like serial ports, except that they always have a modem attached to the port.
 
 The [.filename]#GENERIC# kernel includes support for two serial ports using the same IRQ and port address settings in the above example. If these settings are not right for the system, or if there are more modem cards or serial ports than the kernel is configured for, reconfigure using the instructions in <<make-kernel,building a kernel>> for more details.
 
 [[access-serial-ports]]
 === How do I access the serial ports on FreeBSD? (x86-specific)
 
 The third serial port, [.filename]#sio2#, or [.filename]#COM3#, is on [.filename]#/dev/cuad2# for dial-out devices, and on [.filename]#/dev/ttyd2# for dial-in devices. What is the difference between these two classes of devices?
 
 When opening [.filename]#/dev/ttydX# in blocking mode, a process will wait for the corresponding [.filename]#cuadX# device to become inactive, and then wait for the carrier detect line to go active. When the [.filename]#cuadX# device is opened, it makes sure the serial port is not already in use by the [.filename]#ttydX# device. If the port is available, it steals it from the [.filename]#ttydX# device. Also, the [.filename]#cuadX# device does not care about carrier detect. With this scheme and an auto-answer modem, remote users can log in and local users can still dial out with the same modem and the system will take care of all the conflicts.
 
 [[enable-multiport-serial]]
 === How do I enable support for a multi-port serial card?
 
 The section on kernel configuration provides information about configuring the kernel. For a multi-port serial card, place an man:sio[4] line for each serial port on the card in the man:device.hints[5] file. But place the IRQ specifiers on only one of the entries. All of the ports on the card should share one IRQ. For consistency, use the last serial port to specify the IRQ. Also, specify the following option in the kernel configuration file:
 
 [.programlisting]
 ....
 options COM_MULTIPORT
 ....
 
 The following [.filename]#/boot/device.hints# example is for an AST 4-port serial card on IRQ 12:
 
 [.programlisting]
 ....
 hint.sio.4.at="isa"
 hint.sio.4.port="0x2a0"
 hint.sio.4.flags="0x701"
 hint.sio.5.at="isa"
 hint.sio.5.port="0x2a8"
 hint.sio.5.flags="0x701"
 hint.sio.6.at="isa"
 hint.sio.6.port="0x2b0"
 hint.sio.6.flags="0x701"
 hint.sio.7.at="isa"
 hint.sio.7.port="0x2b8"
 hint.sio.7.flags="0x701"
 hint.sio.7.irq="12"
 ....
 
 The flags indicate that the master port has minor number `7` (`0x700`), and all the ports share an IRQ (`0x001`).
 
 [[default-serial-params]]
 === Can I set the default serial parameters for a port?
 
 See the link:{handbook}#serial/#serial-hw-config[Serial Communications] section in the FreeBSD Handbook.
 
 [[cannot-tip]]
 === Why can I not run tip or cu?
 
 The built-in man:tip[1] and man:cu[1] utilities can only access the [.filename]#/var/spool/lock# directory via user `uucp` and group `dialer`. Use the `dialer` group to control who has access to the modem or remote systems by adding user accounts to `dialer`.
 
 Alternatively, everyone can be configured to run man:tip[1] and man:cu[1] by typing:
 
 [source,shell]
 ....
 # chmod 4511 /usr/bin/cu
 # chmod 4511 /usr/bin/tip
 ....
 
 [[misc]]
 == Miscellaneous Questions
 
 [[more-swap]]
 === FreeBSD uses a lot of swap space even when the computer has free memory left. Why?
 
 FreeBSD will proactively move entirely idle, unused pages of main memory into swap in order to make more main memory available for active use. This heavy use of swap is balanced by using the extra free memory for caching.
 
 Note that while FreeBSD is proactive in this regard, it does not arbitrarily decide to swap pages when the system is truly idle. Thus, the system will not be all paged out after leaving it idle overnight.
 
 [[top-freemem]]
 === Why does top show very little free memory even when I have very few programs running?
 
 The simple answer is that free memory is wasted memory. Any memory that programs do not actively allocate is used within the FreeBSD kernel as disk cache. The values shown by man:top[1] labeled as `Inact` and `Laundry` are cached data at different aging levels. This cached data means the system does not have to access a slow disk again for data it has accessed recently, thus increasing overall performance. In general, a low value shown for `Free` memory in man:top[1] is good, provided it is not _very_ low.
 
 [[chmod-symlinks]]
 === Why will `chmod` not change the permissions on symlinks?
 
 Symlinks do not have permissions, and by default, man:chmod[1] will follow symlinks to change the permissions on the source file, if possible. For the file, [.filename]#foo# with a symlink named [.filename]#bar#, this command will always succeed.
 
 [source,shell]
 ....
 % chmod g-w bar
 ....
 
 However, the permissions on [.filename]#bar# will not have changed.
 
 When changing modes of the file hierarchies rooted in the files instead of the files themselves, use either `-H` or `-L` together with `-R` to make this work. See man:chmod[1] and man:symlink[7] for more information.
 
 [WARNING]
 ====
 
 `-R` does a _recursive_ man:chmod[1]. Be careful about specifying directories or symlinks to directories to man:chmod[1]. To change the permissions of a directory referenced by a symlink, use man:chmod[1] without any options and follow the symlink with a trailing slash ([.filename]#/#). For example, if [.filename]#foo# is a symlink to directory [.filename]#bar#, to change the permissions of [.filename]#foo# (actually [.filename]#bar#), do something like:
 
 [source,shell]
 ....
 % chmod 555 foo/
 ....
 
 With the trailing slash, man:chmod[1] will follow the symlink, [.filename]#foo#, to change the permissions of the directory, [.filename]#bar#.
 ====
 
 [[dos-binaries]]
 === Can I run DOS binaries under FreeBSD?
 
 Yes. A DOS emulation program, package:emulators/doscmd[], is available in the FreeBSD Ports Collection.
 
 If doscmd will not suffice, package:emulators/pcemu[] emulates an 8088 and enough BIOS services to run many DOS text-mode applications. It requires the X Window System.
 
 The Ports Collection also has package:emulators/dosbox[]. The main focus of this application is emulating old DOS games using the local file system for files.
 
 [[translation]]
 === What do I need to do to translate a FreeBSD document into my native language?
 
 See the link:{fdp-primer}#translations/[Translation FAQ] in the FreeBSD Documentation Project Primer.
 
 [[freebsd-mail-bounces]]
 === Why does my email to any address at FreeBSD.org bounce?
 
 The `FreeBSD.org` mail system implements some Postfix checks on incoming mail and rejects mail that is either from misconfigured relays or otherwise appears likely to be spam. Some of the specific requirements are:
 
 * The IP address of the SMTP client must "reverse-resolve" to a forward confirmed hostname.
 * The fully-qualified hostname given in the SMTP conversation (either HELO or EHLO) must resolve to the IP address of the client.
 
 Other advice to help mail reach its destination include:
 
 * Mail should be sent in plain text, and messages sent to mailing lists should generally be no more than 200KB in length.
 * Avoid excessive cross posting. Choose _one_ mailing list which seems most relevant and send it there.
 
 If you still have trouble with email infrastructure at `FreeBSD.org`, send a note with the details to mailto:postmaster@freebsd.org[postmaster@freebsd.org]; Include a date/time interval so that logs may be reviewed - and note that we only keep one week's worth of mail logs. (Be sure to specify the time zone or offset from UTC.)
 
 [[free-account]]
 === Where can I find a free FreeBSD account?
 
 While FreeBSD does not provide open access to any of their servers, others do provide open access UNIX(R) systems. The charge varies and limited services may be available.
 
 http://www.arbornet.org/[Arbornet, Inc], also known as _M-Net_, has been providing open access to UNIX(R) systems since 1983. Starting on an Altos running System III, the site switched to BSD/OS in 1991. In June of 2000, the site switched again to FreeBSD. _M-Net_ can be accessed via telnet and SSH and provides basic access to the entire FreeBSD software suite. However, network access is limited to members and patrons who donate to the system, which is run as a non-profit organization. _M-Net_ also provides an bulletin board system and interactive chat.
 
 [[daemon-name]]
 === What is the cute little red guy's name?
 
 He does not have one, and is just called "the BSD daemon". If you insist upon using a name, call him "beastie". Note that "beastie" is pronounced "BSD".
 
 More about the BSD daemon is available on his http://www.mckusick.com/beastie/index.html[home page].
 
 [[use-beastie]]
 === Can I use the BSD daemon image?
 
 Perhaps. The BSD daemon is copyrighted by Marshall Kirk McKusick. Check his http://www.mckusick.com/beastie/mainpage/copyright.html[Statement on the Use of the BSD Daemon Figure] for detailed usage terms.
 
 In summary, the image can be used in a tasteful manner, for personal use, so long as appropriate credit is given. Before using the logo commercially, contact {mckusick} for permission. More details are available on the http://www.mckusick.com/beastie/index.html[BSD Daemon's home page].
 
 [[daemon-images]]
 === Do you have any BSD daemon images I could use?
 
 Xfig and eps drawings are available under [.filename]#/usr/share/examples/BSD_daemon/#.
 
 [[glossary]]
 === I have seen an acronym or other term on the mailing lists and I do not understand what it means. Where should I look?
 
 Refer to the link:{handbook}#freebsd-glossary/[FreeBSD Glossary].
 
 [[bikeshed-painting]]
 === Why should I care what color the bikeshed is?
 
 The really, really short answer is that you should not. The somewhat longer answer is that just because you are capable of building a bikeshed does not mean you should stop others from building one just because you do not like the color they plan to paint it. This is a metaphor indicating that you need not argue about every little feature just because you know enough to do so. Some people have commented that the amount of noise generated by a change is inversely proportional to the complexity of the change.
 
 The longer and more complete answer is that after a very long argument about whether man:sleep[1] should take fractional second arguments, {phk} posted a long message entitled link:http://www.bikeshed.com[A bike shed (any color will do) on greener grass...]. The appropriate portions of that message are quoted below.
 
 ****
 “What is it about this bike shed?” Some of you have asked me.
 
 It is a long story, or rather it is an old story, but it is quite short actually. C. Northcote Parkinson wrote a book in the early 1960s, called “Parkinson's Law”, which contains a lot of insight into the dynamics of management.
 
 [snip a bit of commentary on the book]
 
 In the specific example involving the bike shed, the other vital component is an atomic power-plant, I guess that illustrates the age of the book.
 
 Parkinson shows how you can go into the board of directors and get approval for building a multi-million or even billion dollar atomic power plant, but if you want to build a bike shed you will be tangled up in endless discussions.
 
 Parkinson explains that this is because an atomic plant is so vast, so expensive and so complicated that people cannot grasp it, and rather than try, they fall back on the assumption that somebody else checked all the details before it got this far. Richard P. Feynmann gives a couple of interesting, and very much to the point, examples relating to Los Alamos in his books.
 
 A bike shed on the other hand. Anyone can build one of those over a weekend, and still have time to watch the game on TV. So no matter how well prepared, no matter how reasonable you are with your proposal, somebody will seize the chance to show that he is doing his job, that he is paying attention, that he is here.
 
 In Denmark we call it “setting your fingerprint”. It is about personal pride and prestige, it is about being able to point somewhere and say “There! I did that.” It is a strong trait in politicians, but present in most people given the chance. Just think about footsteps in wet cement.
 
 --Poul-Henning Kamp <phk@FreeBSD.org> on freebsd-hackers, October 2, 1999
 ****
 
 [[funnies]]
 == The FreeBSD Funnies
 
 [[very-very-cool]]
 === How cool is FreeBSD?
 
 [qanda]
 Q::Has anyone done any temperature testing while running FreeBSD? I know Linux(R) runs cooler than DOS, but have never seen a mention of FreeBSD. It seems to run really hot.
 A:: No, but we have done numerous taste tests on blindfolded volunteers who have also had 250 micrograms of LSD-25 administered beforehand. 35% of the volunteers said that FreeBSD tasted sort of orange, whereas Linux(R) tasted like purple haze. Neither group mentioned any significant variances in temperature. We eventually had to throw the results of this survey out entirely anyway when we found that too many volunteers were wandering out of the room during the tests, thus skewing the results. We think most of the volunteers are at Apple now, working on their new "scratch and sniff" GUI. It is a funny old business we are in!
 
 Seriously, FreeBSD uses the HLT (halt) instruction when the system is idle thus lowering its energy consumption and therefore the heat it generates. Also if you have ACPI (Advanced Configuration and Power Interface) configured, then FreeBSD can also put the CPU into a low power mode.
 
 [[letmeoutofhere]]
 === Who is scratching in my memory banks??
 
 [qanda]
 Q:: Is there anything "odd" that FreeBSD does when compiling the kernel which would cause the memory to make a scratchy sound? When compiling (and for a brief moment after recognizing the floppy drive upon startup, as well), a strange scratchy sound emanates from what appears to be the memory banks.
 A:: Yes! You will see frequent references to "daemons" in the BSD documentation, and what most people do not know is that this refers to genuine, non-corporeal entities that now possess your computer. The scratchy sound coming from your memory is actually high-pitched whispering exchanged among the daemons as they best decide how to deal with various system administration tasks.
 
 If the noise gets to you, a good `fdisk /mbr` from DOS will get rid of them, but do not be surprised if they react adversely and try to stop you. In fact, if at any point during the exercise you hear the satanic voice of Bill Gates coming from the built-in speaker, take off running and do not ever look back! Freed from the counterbalancing influence of the BSD daemons, the twin demons of DOS and Windows(R) are often able to re-assert total control over your machine to the eternal damnation of your soul. Now that you know, given a choice you would probably prefer to get used to the scratchy noises, no?
 
 [[changing-lightbulbs]]
 === How many FreeBSD hackers does it take to change a lightbulb?
 
 One thousand, one hundred and sixty-nine:
 
 Twenty-three to complain to -CURRENT about the lights being out;
 
 Four to claim that it is a configuration problem, and that such matters really belong on -questions;
 
 Three to submit PRs about it, one of which is misfiled under doc and consists only of "it's dark";
 
 One to commit an untested lightbulb which breaks buildworld, then back it out five minutes later;
 
 Eight to flame the PR originators for not including patches in their PRs;
 
 Five to complain about buildworld being broken;
 
 Thirty-one to answer that it works for them, and they must have updated at a bad time;
 
 One to post a patch for a new lightbulb to -hackers;
 
 One to complain that he had patches for this three years ago, but when he sent them to -CURRENT they were just ignored, and he has had bad experiences with the PR system; besides, the proposed new lightbulb is non-reflexive;
 
 Thirty-seven to scream that lightbulbs do not belong in the base system, that committers have no right to do things like this without consulting the Community, and WHAT IS -CORE DOING ABOUT IT!?
 
 Two hundred to complain about the color of the bicycle shed;
 
 Three to point out that the patch breaks man:style[9];
 
 Seventeen to complain that the proposed new lightbulb is under GPL;
 
 Five hundred and eighty-six to engage in a flame war about the comparative advantages of the GPL, the BSD license, the MIT license, the NPL, and the personal hygiene of unnamed FSF founders;
 
 Seven to move various portions of the thread to -chat and -advocacy;
 
 One to commit the suggested lightbulb, even though it shines dimmer than the old one;
 
 Two to back it out with a furious flame of a commit message, arguing that FreeBSD is better off in the dark than with a dim lightbulb;
 
 Forty-six to argue vociferously about the backing out of the dim lightbulb and demanding a statement from -core;
 
 Eleven to request a smaller lightbulb so it will fit their Tamagotchi if we ever decide to port FreeBSD to that platform;
 
 Seventy-three to complain about the SNR on -hackers and -chat and unsubscribe in protest;
 
 Thirteen to post "unsubscribe", "How do I unsubscribe?", or "Please remove me from the list", followed by the usual footer;
 
 One to commit a working lightbulb while everybody is too busy flaming everybody else to notice;
 
 Thirty-one to point out that the new lightbulb would shine 0.364% brighter if compiled with TenDRA (although it will have to be reshaped into a cube), and that FreeBSD should therefore switch to TenDRA instead of GCC;
 
 One to complain that the new lightbulb lacks fairings;
 
 Nine (including the PR originators) to ask "what is MFC?";
 
 Fifty-seven to complain about the lights being out two weeks after the bulb has been changed.
 
 _{nik} adds:_
 
 _I was laughing quite hard at this._
 
 _And then I thought, "Hang on, shouldn't there be '1 to document it.' in that list somewhere?"_
 
 _And then I was enlightened :-)_
 
 _{tabthorpe}_ says: "None, _real_ FreeBSD hackers are not afraid of the dark!"
 
 [[dev-null]]
 === Where does data written to [.filename]#/dev/null# go?
 
 It goes into a special data sink in the CPU where it is converted to heat which is vented through the heatsink / fan assembly. This is why CPU cooling is increasingly important; as people get used to faster processors, they become careless with their data and more and more of it ends up in [.filename]#/dev/null#, overheating their CPUs. If you delete [.filename]#/dev/null# (which effectively disables the CPU data sink) your CPU may run cooler but your system will quickly become constipated with all that excess data and start to behave erratically. If you have a fast network connection you can cool down your CPU by reading data out of [.filename]#/dev/random# and sending it off somewhere; however you run the risk of overheating your network connection and [.filename]#/# or angering your ISP, as most of the data will end up getting converted to heat by their equipment, but they generally have good cooling, so if you do not overdo it you should be OK.
 
 _Paul Robinson adds:_
 
 There are other methods. As every good sysadmin knows, it is part of standard practice to send data to the screen of interesting variety to keep all the pixies that make up your picture happy. Screen pixies (commonly mis-typed or re-named as "pixels") are categorized by the type of hat they wear (red, green or blue) and will hide or appear (thereby showing the color of their hat) whenever they receive a little piece of food. Video cards turn data into pixie-food, and then send them to the pixies - the more expensive the card, the better the food, so the better behaved the pixies are. They also need constant stimulation - this is why screen savers exist.
 
 To take your suggestions further, you could just throw the random data to console, thereby letting the pixies consume it. This causes no heat to be produced at all, keeps the pixies happy and gets rid of your data quite quickly, even if it does make things look a bit messy on your screen.
 
 Incidentally, as an ex-admin of a large ISP who experienced many problems attempting to maintain a stable temperature in a server room, I would strongly discourage people sending the data they do not want out to the network. The fairies who do the packet switching and routing get annoyed by it as well.
 
 [[punk-my-friend]]
 === My colleague sits at the computer too much, how can I prank her?
 
 Install package:games/sl[] and wait for her to mistype `sl` for `ls`.
 
 [[advanced]]
 == Advanced Topics
 
 [[learn-advanced]]
 === How can I learn more about FreeBSD's internals?
 
 See the link:{arch-handbook}[FreeBSD Architecture Handbook].
 
 Additionally, much general UNIX(R) knowledge is directly applicable to FreeBSD.
 
 [[how-to-contribute]]
 === How can I contribute to FreeBSD? What can I do to help?
 
 We accept all types of contributions: documentation, code, and even art. See the article on link:{contributing}[Contributing to FreeBSD] for specific advice on how to do this.
 
 And thanks for the thought!
 
 [[define-snap-release]]
 === What are snapshots and releases?
 
 There are currently {rel-numbranch} active/semi-active branches in the FreeBSD http://svnweb.FreeBSD.org/base/[Subversion Repository]. (Earlier branches are only changed very rarely, which is why there are only {rel-numbranch} active branches of development):
 
 * {rel2-releng} AKA {rel2-stable}
 * {rel-releng} AKA {rel-stable}
 * {rel-head-releng} AKA _-CURRENT_ AKA {rel-head}
 
 `HEAD` is not an actual branch tag. It is a symbolic constant for the current, non-branched development stream known as _-CURRENT_.
 
 Right now, _-CURRENT_ is the {rel-head-relx} development stream; the {rel-stable} branch, {rel-releng}, forked off from _-CURRENT_ in {rel-relengdate} and the {rel2-stable} branch, {rel2-releng}, forked off from _-CURRENT_ in {rel2-relengdate}.
 
 [[kernel-panic-troubleshooting]]
 === How can I make the most of the data I see when my kernel panics?
 
 Here is typical kernel panic:
 
 [.programlisting]
 ....
 Fatal trap 12: page fault while in kernel mode
 fault virtual address   = 0x40
 fault code              = supervisor read, page not present
 instruction pointer     = 0x8:0xf014a7e5
 stack pointer           = 0x10:0xf4ed6f24
 frame pointer           = 0x10:0xf4ed6f28
 code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, def32 1, gran 1
 processor eflags        = interrupt enabled, resume, IOPL = 0
 current process         = 80 (mount)
 interrupt mask          =
 trap number             = 12
 panic: page fault
 ....
 
 This message is not enough. While the instruction pointer value is important, it is also configuration dependent as it varies depending on the kernel image. If it is a [.filename]#GENERIC# kernel image from one of the snapshots, it is possible for somebody else to track down the offending function, but for a custom kernel, only you can tell us where the fault occurred.
 
 To proceed:
 
 [.procedure]
 ====
 . Write down the instruction pointer value. Note that the `0x8:` part at the beginning is not significant in this case: it is the `0xf0xxxxxx` part that we want.
 . When the system reboots, do the following:
 +
 [source,shell]
 ....
 % nm -n kernel.that.caused.the.panic | grep f0xxxxxx
 ....
-+ 
++
 where `f0xxxxxx` is the instruction pointer value. The odds are you will not get an exact match since the symbols in the kernel symbol table are for the entry points of functions and the instruction pointer address will be somewhere inside a function, not at the start. If you do not get an exact match, omit the last digit from the instruction pointer value and try again:
 +
 [source,shell]
 ....
 % nm -n kernel.that.caused.the.panic | grep f0xxxxx
 ....
-+ 
++
 If that does not yield any results, chop off another digit. Repeat until there is some sort of output. The result will be a possible list of functions which caused the panic. This is a less than exact mechanism for tracking down the point of failure, but it is better than nothing.
 ====
 
 However, the best way to track down the cause of a panic is by capturing a crash dump, then using man:kgdb[1] to generate a stack trace on the crash dump.
 
 In any case, the method is this:
 
 [.procedure]
 ====
 . Make sure that the following line is included in the kernel configuration file:
 +
 [.programlisting]
 ....
 makeoptions     DEBUG=-g          # Build kernel with gdb(1) debug symbols
 ....
 
 . Change to the [.filename]#/usr/src# directory:
 +
 [source,shell]
 ....
 # cd /usr/src
 ....
 
 . Compile the kernel:
 +
 [source,shell]
 ....
 # make buildkernel KERNCONF=MYKERNEL
 ....
 
 . Wait for man:make[1] to finish compiling.
 +
 [source,shell]
 ....
 # make installkernel KERNCONF=MYKERNEL
 ....
 
 . Reboot.
 ====
 
 [NOTE]
 ====
 If `KERNCONF` is not included, the [.filename]#GENERIC# kernel will instead be built and installed.
 ====
 
 The man:make[1] process will have built two kernels. [.filename]#/usr/obj/usr/src/sys/MYKERNEL/kernel# and [.filename]#/usr/obj/usr/src/sys/MYKERNEL/kernel.debug#. [.filename]#kernel# was installed as [.filename]#/boot/kernel/kernel#, while [.filename]#kernel.debug# can be used as the source of debugging symbols for man:kgdb[1].
 
 To capture a crash dump, edit [.filename]#/etc/rc.conf# and set `dumpdev` to point to either the swap partition or `AUTO`. This will cause the man:rc[8] scripts to use the man:dumpon[8] command to enable crash dumps. This command can also be run manually. After a panic, the crash dump can be recovered using man:savecore[8]; if `dumpdev` is set in [.filename]#/etc/rc.conf#, the man:rc[8] scripts will run man:savecore[8] automatically and put the crash dump in [.filename]#/var/crash#.
 
 [NOTE]
 ====
 FreeBSD crash dumps are usually the same size as physical RAM. Therefore, make sure there is enough space in [.filename]#/var/crash# to hold the dump. Alternatively, run man:savecore[8] manually and have it recover the crash dump to another directory with more room. It is possible to limit the size of the crash dump by using `options MAXMEM=N` where _N_ is the size of kernel's memory usage in KBs. For example, for 1 GB of RAM, limit the kernel's memory usage to 128 MB, so that the crash dump size will be 128 MB instead of 1 GB.
 ====
 
 Once the crash dump has been recovered , get a stack trace as follows:
 
 [source,shell]
 ....
 % kgdb /usr/obj/usr/src/sys/MYKERNEL/kernel.debug /var/crash/vmcore.0
 (kgdb) backtrace
 ....
 
 Note that there may be several screens worth of information. Ideally, use man:script[1] to capture all of them. Using the unstripped kernel image with all the debug symbols should show the exact line of kernel source code where the panic occurred. The stack trace is usually read from the bottom up to trace the exact sequence of events that lead to the crash. man:kgdb[1] can also be used to print out the contents of various variables or structures to examine the system state at the time of the crash.
 
 [TIP]
 ====
 
 If a second computer is available, man:kgdb[1] can be configured to do remote debugging, including setting breakpoints and single-stepping through the kernel code.
 ====
 
 [NOTE]
 ====
 If `DDB` is enabled and the kernel drops into the debugger, a panic and a crash dump can be forced by typing `panic` at the `ddb` prompt. It may stop in the debugger again during the panic phase. If it does, type `continue` and it will finish the crash dump.
 ====
 
 [[dlsym-failure]]
 === Why has dlsym() stopped working for ELF executables?
 
 The ELF toolchain does not, by default, make the symbols defined in an executable visible to the dynamic linker. Consequently `dlsym()` searches on handles obtained from calls to `dlopen(NULL, flags)` will fail to find such symbols.
 
 To search, using `dlsym()`, for symbols present in the main executable of a process, link the executable using the `--export-dynamic` option to the ELF linker (man:ld[1]).
 
 [[change-kernel-address-space]]
 === How can I increase or reduce the kernel address space on i386?
 
 By default, the kernel address space is 1 GB (2 GB for PAE) for i386. When running a network-intensive server or using ZFS, this will probably not be enough.
 
 Add the following line to the kernel configuration file to increase available space and rebuild the kernel:
 
 [.programlisting]
 ....
 options KVA_PAGES=N
 ....
 
 To find the correct value of _N_, divide the desired address space size (in megabytes) by four. (For example, it is `512` for 2 GB.)
 
 [[acknowledgments]]
 == Acknowledgments
 
 This innocent little Frequently Asked Questions document has been written, rewritten, edited, folded, spindled, mutilated, eviscerated, contemplated, discombobulated, cogitated, regurgitated, rebuilt, castigated, and reinvigorated over the last decade, by a cast of hundreds if not thousands. Repeatedly.
 
 We wish to thank every one of the people responsible, and we encourage you to link:{contributing}[join them] in making this FAQ even better.
diff --git a/documentation/content/en/books/fdp-primer/overview/_index.adoc b/documentation/content/en/books/fdp-primer/overview/_index.adoc
index 10551ad3a2..2fef4f9b53 100644
--- a/documentation/content/en/books/fdp-primer/overview/_index.adoc
+++ b/documentation/content/en/books/fdp-primer/overview/_index.adoc
@@ -1,124 +1,124 @@
 ---
 title: Chapter 1. Overview
 prev: books/fdp-primer/preface
 next: books/fdp-primer/tools
 description: Overview about the FreeBSD Documentation Process
 tags: ["overview", "FreeBSD Documentation Project", "quick start"]
 ---
 
 [[overview]]
 = Overview
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 1
 
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 
 Welcome to the FreeBSD Documentation Project (FDP).
 Quality documentation is crucial to the success of FreeBSD, and we value your contributions very highly.
 
 This document describes how the FDP is organized, how to write and submit documentation, and how to effectively use the available tools.
 
 Everyone is welcome to contribute to the FDP.
 Willingness to contribute is the only membership requirement.
 
 This primer shows how to:
 
 * Identify which parts of FreeBSD are maintained by the FDP.
 * Install the required documentation tools and files.
 * Make changes to the documentation.
 * Submit changes back for review and inclusion in the FreeBSD documentation.
 
 [[overview-quick-start]]
 == Quick Start
 
 Some preparatory steps must be taken before editing the FreeBSD documentation.
 First, subscribe to the {freebsd-doc}.
 Some team members also interact on the `#bsddocs` IRC channel on http://www.efnet.org/[EFnet].
 These people can help with questions or problems involving the documentation.
 
 [.procedure]
 ====
 . Install these packages. These packages are all of the software needed to edit and build FreeBSD documentation. The Git package is needed to obtain a working copy of the documentation and generate patches with.
 +
 [source,shell]
 ....
 # pkg install gohugo python3 git-lite rubygem-asciidoctor rubygem-rouge
 ....
 +
 . Optional: to generate PDF documentation install `asciidoctor-pdf`
 +
 [source,shell]
 ....
 # pkg install rubygem-asciidoctor-pdf 
 ....
 +
 . Install a local working copy of the documentation from the FreeBSD repository in [.filename]#~/doc# (see crossref:working-copy[working-copy,The Working Copy]).
 +
 [source,shell]
 ....
 % git clone https://git.FreeBSD.org/doc.git ~/doc
 ....
 +
 . Edit the documentation files that require changes. If a file needs major changes, consult the mailing list for input.
-+ 
++
 Review the output and edit the file to fix any problems shown, then rerun the command to find any remaining problems.
 Repeat until all of the errors are resolved.
 +
 . *_Always_* build and test the changes before submitting them. Running `make` in the top-level directory of the documentation will generate that documentation in HTML format.
 +
 [source,shell]
 ....
 % make
 ....
 +
 . When changes are complete and tested, generate a "diff file":
 +
 [source,shell]
 ....
 % cd ~/doc
 % git diff > bsdinstall.diff.txt
 ....
-+ 
++
 Give the diff file a descriptive name.
 In the example above, changes have been made to the [.filename]#bsdinstall# portion of the Handbook.
 . Submit the diff file using the web-based https://bugs.FreeBSD.org/bugzilla/enter_bug.cgi?product=Documentation[Problem Report] system. If using the web form, enter a Summary of _[patch] short description of problem_. Select the Component `Documentation`. In the Description field, enter a short description of the changes and any important details about them. Use the btn:[Add an attachment] button to attach the diff file. Finally, use the btn:[Submit Bug] button to submit your diff to the problem report system.
 ====
 
 [[overview-doc]]
 == The FreeBSD Documentation Set
 
 The FDP is responsible for four categories of FreeBSD documentation.
 
 * _Handbook_: The Handbook is the comprehensive online resource and reference for FreeBSD users.
 * _FAQ_: The FAQ uses a short question and answer format to address questions that are frequently asked on the various mailing lists and forums devoted to FreeBSD. This format does not permit long and comprehensive answers.
 * _Manual pages_: The English language system manual pages are usually not written by the FDP, as they are part of the base system. However, the FDP can reword parts of existing manual pages to make them clearer or to correct inaccuracies.
 * _Web site_: This is the main FreeBSD presence on the web, visible at https://www.freebsd.org/[https://www.FreeBSD.org/] and many mirrors around the world. The web site is typically a new user's first exposure to FreeBSD.
 
 Translation teams are responsible for translating the Handbook and web site into different languages.
 Manual pages are not translated at present.
 
 Documentation source for the FreeBSD web site, Handbook, and FAQ is available in the documentation repository at `https://cgit.freebsd.org/doc/`.
 
 Source for manual pages is available in a separate source repository located at `https://cgit.freebsd.org/src/`.
 
 Documentation commit messages are visible with `git log`.
 Commit messages are also archived at link:{git-doc-all}.
 
 Web frontends to both of these repositories are available at https://cgit.freebsd.org/doc/[] and https://cgit.freebsd.org/src/[].
 
 Many people have written tutorials or how-to articles about FreeBSD.
 Some are stored as part of the FDP files.
 In other cases, the author has decided to keep the documentation separate.
 The FDP endeavors to provide links to as much of this external documentation as possible.
diff --git a/documentation/content/en/books/fdp-primer/po-translations/_index.adoc b/documentation/content/en/books/fdp-primer/po-translations/_index.adoc
index 8dc6a58602..7e33cf1742 100644
--- a/documentation/content/en/books/fdp-primer/po-translations/_index.adoc
+++ b/documentation/content/en/books/fdp-primer/po-translations/_index.adoc
@@ -1,420 +1,420 @@
 ---
 title: Chapter 9. PO Translations
 prev: books/fdp-primer/translations
 next: books/fdp-primer/manual-pages
 description: How to work with PO translation in the FreeBSD Documentation Project
 tags: ["po", "translations", "tutorial", "quick start"]
 ---
 
 [[po-translations]]
 = PO Translations
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 9
 
 include::shared/en/urls.adoc[]
 
 toc::[] 
 
 [[po-translations-introduction]]
 == Introduction
 
 The http://www.gnu.org/software/gettext/[GNU gettext] system offers translators an easy way to create and maintain translations of documents.
 Translatable strings are extracted from the original document into a PO (Portable Object) file.
 Translated versions of the strings are entered with a separate editor.
 The strings can be used directly or built into a complete translated version of the original document.
 
 [[po-translations-quick-start]]
 == Quick Start
 
 The procedure shown in crossref:overview[overview-quick-start,Quick Start] is assumed to have already been performed.
 The `TRANSLATOR` option is required and already enabled by default in the package:textproc/docproj[] port.
 
 This example shows the creation of a Spanish translation of the short link:{leap-seconds}[Leap Seconds] article.
 
 [[po-translations-quick-start-install-po-editor]]
 
 [.procedure]
 ====
 .Procedure: Install a PO Editor
 . A PO editor is needed to edit translation files. This example uses package:editors/poedit[].
 +
 [source,shell]
 ....
 # pkg install poedit
 ....
 ====
 
 [[po-translations-quick-start-initial-setup]]
 [.procedure]
 ====
 .Procedure: Initial Setup
 
 When a new translation is first created, the directory structure must be created or copied from the English original:
 
 . Create a directory for the new translation. The English article source is in [.filename]#~/doc/documentation/content/en/articles/leap-seconds/#. The Spanish translation will go in [.filename]#~/doc/documentation/content/es/articles/leap-seconds/#. The path is the same except for the name of the language directory.
 The English article source is in [.filename]#~/doc/en/articles/leap-seconds/#.
 The Spanish translation will go in [.filename]#~/doc/es/articles/leap-seconds/#.
 The path is the same except for the name of the language directory.
 +
 [source,shell]
 ....
 % mkdir ~/doc/documentation/content/es/articles/leap-seconds
 ....
 
 . Copy the [.filename]#_index.adoc# from the original document into the translation directory:
 +
 [source,shell]
 ....
 % cp ~/doc/documentation/content/en/articles/leap-seconds/_index.adoc \
   ~/doc/documentation/content/es/articles/leap-seconds/
 ....
 ====
 
 [[po-translations-quick-start-translation]]
 [.procedure]
 ====
 .Procedure: Translation
 
 Translating a document consists of two steps: extracting translatable strings from the original document, and entering translations for those strings.
 These steps are repeated until the translator feels that enough of the document has been translated to produce a usable translated document.
 
 . Extract the translatable strings from the original English version into a PO file:
 +
 [source,shell]
 ....
 % cd ~/doc
 % po4a-gettextize \
   --format asciidoc \
   --option compat=asciidoctor \
   --option yfm_keys=title,part,description \
   --master "documentation/content/en/articles/leap-seconds/_index.adoc" \
   --master-charset "UTF-8" \
   --copyright-holder "The FreeBSD Project" \
   --package-name "FreeBSD Documentation" \
   --po "documentation/content/es/articles/leap-seconds/_index.po"
 ....
 +
 . Use a PO editor to enter translations in the PO file. There are several different editors available. [.filename]#poedit# from package:editors/poedit[] is shown here.
-+ 
++
 [source,shell]
 ....
 % poedit documentation/content/es/articles/leap-seconds/_index.po
 ....
 ====
 
 [[po-translations-quick-generating-a-translated-document]]
 [.procedure]
 ====
 .Procedure: Generating a Translated Document
 . Generate the translated document:
 +
 [source,shell]
 ....
 % cd ~/doc
 % po4a-translate \
   --format asciidoc \
   --option compat=asciidoctor \
   --option yfm_keys=title,part,description \
   --master "documentation/content/en/articles/leap-seconds/_index.adoc" \
   --master-charset "UTF-8" \
   --po "documentation/content/es/articles/leap-seconds/_index.po" \
   --localized "documentation/content/es/articles/leap-seconds/_index.adoc" \
   --localized-charset "UTF-8" \
   --keep 0
 ....
-+ 
++
 The name of the generated document matches the name of the English original, usually [.filename]#_index.adoc#.
 +
 . Check the generated file by rendering it to HTML and viewing it with a web browser:
 +
 [source,shell]
 ....
 % cd ~/doc/documentation
 % make
 ....
 ====
 
 [[po-translations-creating]]
 == Creating New Translations
 
 The first step to creating a new translated document is locating or creating a directory to hold it.
 FreeBSD puts translated documents in a subdirectory named for their language and region in the format [.filename]#lang#.
 _lang_ is a two-character lowercase code.
 
 [[po-translations-language-names]]
 .Language Names
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Language
 | Region
 | Translated Directory Name
 
 |English
 |United States
 |[.filename]#en#
 
 |Bengali
 |Bangladesh
 |[.filename]#bn#
 
 |Danish
 |Denmark
 |[.filename]#da#
 
 |German
 |Germany
 |[.filename]#de#
 
 |Greek
 |Greece
 |[.filename]#el#
 
 |Spanish
 |Spain
 |[.filename]#es#
 
 |French
 |France
 |[.filename]#fr#
 
 |Hungarian
 |Hungary
 |[.filename]#hu#
 
 |Italian
 |Italy
 |[.filename]#it#
 
 |Japanese
 |Japan
 |[.filename]#ja#
 
 |Korean
 |Korea
 |[.filename]#ko#
 
 |Mongolian
 |Mongolia
 |[.filename]#mn#
 
 |Dutch
 |Netherlands
 |[.filename]#nl#
 
 |Polish
 |Poland
 |[.filename]#pl#
 
 |Portuguese
 |Brazil
 |[.filename]#pt-br#
 
 |Russian
 |Russia
 |[.filename]#ru#
 
 |Turkish
 |Turkey
 |[.filename]#tr#
 
 |Chinese
 |China
 |[.filename]#zh-cn#
 
 |Chinese
 |Taiwan
 |[.filename]#zh-tw#
 |===
 
 The translations are in subdirectories of the main documentation directory,
 here assumed to be [.filename]#~/doc/documentation/# as shown in <<overview-quick-start>>.
 For example, German translations are located in [.filename]#~/doc/documentation/content/de/#,
 and French translations are in [.filename]#~/doc/documentation/content/fr/#.
 
 Each language directory contains separate subdirectories named for the type of documents, usually [.filename]#articles/# and [.filename]#books/#.
 
 Combining these directory names gives the complete path to an article or book.
 For example, the French translation of the NanoBSD article is in [.filename]#~/doc/documentation/content/fr/articles/nanobsd/#,
 and the Mongolian translation of the Handbook is in [.filename]#~/doc/documentation/content/mn/books/handbook/#.
 
 A new language directory must be created when translating a document to a new language.
 If the language directory already exists, only a subdirectory in the [.filename]#articles/# or [.filename]#books/# directory is needed.
 
 [[po-translations-creating-example]]
 .Creating a Spanish Translation of the Porter's Handbook
 [example]
 ====
 Create a new Spanish translation of the link:{porters-handbook}[Porter's Handbook].
 The original is a book in [.filename]#~/doc/documentation/content/en/books/porters-handbook/#.
 
 [.procedure]
 ======
 
 . The Spanish language books directory [.filename]#~/doc/documentation/content/es/books/# already exists, so only a new subdirectory for the Porter's Handbook is needed:
 +
 [source,shell]
 ....
 % cd ~/doc/documentation/content/es/books
 % mkdir porters-handbook
 ....
 
 . Copy the content from the original book:
 +
 [source,shell]
 ....
 % cd porters-handbook
 % cp -R ~/doc/documentation/content/en/books/porters-handbook/* .
 ....
-+ 
++
 Now the document structure is ready for the translator to begin translating with `po4a` command.
 ======
 ====
 
 [[po-translations-translating]]
 == Translating
 
 The gettext system greatly reduces the number of things that must be tracked by a translator.
 Strings to be translated are extracted from the original document into a PO file.
 Then a PO editor is used to enter the translated versions of each string.
 
 The FreeBSD PO translation system does not overwrite PO files, so the extraction step can be run at any time to update the PO file.
 
 A PO editor is used to edit the file.
 package:editors/poedit[] is shown in these examples because it is simple and has minimal requirements.
 Other PO editors offer features to make the job of translating easier.
 The Ports Collection offers several of these editors, including package:devel/gtranslator[].
 
 It is important to preserve the PO file.
 It contains all of the work that translators have done.
 
 [[po-translations-translating-example]]
 .Translating the Porter's Handbook to Spanish
 [example]
 ====
 
 [.procedure]
 ======
 . Change to the base directory and update all PO files.
 +
 [source,shell]
 ....
 % cd ~/doc
 % po4a-gettextize \
   --format asciidoc \
   --option compat=asciidoctor \
   --option yfm_keys=title,part,description \
   --master "documentation/content/en/books/porters-handbook/_index.adoc" \
   --master-charset "UTF-8" \
   --copyright-holder "The FreeBSD Project" \
   --package-name "FreeBSD Documentation" \
   --po "documentation/content/es/books/porters-handbook/_index.po"
 ....
 
 . Enter translations using a PO editor:
 +
 [source,shell]
 ....
 % poedit documentation/content/es/books/porters-handbook/_index.po
 ....
 ======
 
 These steps are necessary for all `.adoc` files, excluding `chapters-order.adoc` and `toc-*.adoc`.
 
 ====
 
 [[po-translations-tips]]
 == Tips for Translators
 
 [[po-translations-tips-xmltags]]
 === Preserving AsciiDoc macros
 
 Preserve AsciiDoc macros that are shown in the English original.
 
 .Preserving AsciiDoc macros
 [example]
 ====
 English original:
 
 [.programlisting]
 ....
 msgid ""
 "This example shows the creation of a Spanish translation of the short "
 "link:{leap-seconds}[Leap Seconds] article."
 ....
 
 Spanish translation:
 
 [.programlisting]
 ....
 msgid ""
 "Este ejemplo muestra la creación de un artículo con poco contenido como el artículo "
 "link:{leap-seconds}[Leap Seconds]."
 ....
 
 ====
 
 [[po-translations-tips-spaces]]
 === Preserving Spaces
 
 Preserve existing spaces at the beginning and end of strings to be translated.
 The translated version must have these spaces also.
 
 [[po-translations-tips-verbatim]]
 === Verbatim Tags
 
 The contents of some tags should be copied verbatim, not translated:
 
 * `man:man[1]`
 * `package:package[]`
 * `link`
 * `image`
 * `include`
 * `Admonitions`
 * `id's`
 * `Heading tags`
 * `source`
 
 [[po-translations-building]]
 == Building a Translated Document
 
 A translated version of the original document can be created at any time.
 Any untranslated portions of the original will be included in English in the resulting document.
 Most PO editors have an indicator that shows how much of the translation has been completed.
 This makes it easy for the translator to see when enough strings have been translated to make building the final document worthwhile.
 
 [[po-translations-submitting]]
 == Submitting the New Translation
 
 Prepare the new translation files for submission.
 This includes adding the files to the version control system, setting additional properties on them, then creating a diff for submission.
 
 The diff files created by these examples can be attached to a https://bugs.freebsd.org/bugzilla/enter_bug.cgi?product=Documentation[documentation bug report] or https://reviews.freebsd.org/[code review].
 
 [[po-translations-submitting-spanish]]
 .Spanish Translation of the NanoBSD Article
 [example]
 ====
 [.procedure]
 ======
 
 . Create a diff of the new files from the [.filename]#~/doc/# base directory so the full path is shown with the filenames. This helps committers identify the target language directory.
 +
 [source,shell]
 ....
 % cd ~/doc
 % git diff documentation/content/es/articles/nanobsd/ > /tmp/es_nanobsd.diff
 ....
 ======
 
 ====
diff --git a/documentation/content/en/books/handbook/advanced-networking/_index.adoc b/documentation/content/en/books/handbook/advanced-networking/_index.adoc
index a64a5e8fa5..b8ea334437 100644
--- a/documentation/content/en/books/handbook/advanced-networking/_index.adoc
+++ b/documentation/content/en/books/handbook/advanced-networking/_index.adoc
@@ -1,3259 +1,3259 @@
 ---
 title: Chapter 32. Advanced Networking
 part: IV. Network Communication
 prev: books/handbook/firewalls
 next: books/handbook/partv
 description: "Advanced networking in FreeBSD:  basics of gateways and routes, CARP, how to configure multiple VLANs on FreeBSD, etc"
 tags: ["Advanced Networking", "Handbook", "gateway", "routes", "wireless", "tethering", "bluetooth", "bridging", "ipv6", "CARP", "VLAN"]
 ---
 
 [[advanced-networking]]
 = Advanced Networking
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 32
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/advanced-networking/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/advanced-networking/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/advanced-networking/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[advanced-networking-synopsis]]
 == Synopsis
 
 This chapter covers a number of advanced networking topics.
 
 After reading this chapter, you will know:
 
 * The basics of gateways and routes.
 * How to set up USB tethering.
 * How to set up IEEE(R) 802.11 and Bluetooth(R) devices.
 * How to make FreeBSD act as a bridge.
 * How to set up network PXE booting.
 * How to set up IPv6 on a FreeBSD machine.
 * How to enable and utilize the features of the Common Address Redundancy Protocol (CARP) in FreeBSD.
 * How to configure multiple VLANs on FreeBSD.
 * Configure bluetooth headset.
 
 Before reading this chapter, you should:
 
 * Understand the basics of the [.filename]#/etc/rc# scripts.
 * Be familiar with basic network terminology.
 * Know how to configure and install a new FreeBSD kernel (crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel]).
 * Know how to install additional third-party software (crossref:ports[ports,Installing Applications: Packages and Ports]).
 
 [[network-routing]]
 == Gateways and Routes
 
 _Routing_ is the mechanism that allows a system to find the network path to another system.
 A _route_ is a defined pair of addresses which represent the "destination" and a "gateway".
 The route indicates that when trying to get to the specified destination, send the packets through the specified gateway.
 There are three types of destinations: individual hosts, subnets, and "default".
 The "default route" is used if no other routes apply.
 There are also three types of gateways: individual hosts, interfaces, also called links, and Ethernet hardware (MAC) addresses.
 Known routes are stored in a routing table.
 
 This section provides an overview of routing basics.
 It then demonstrates how to configure a FreeBSD system as a router and offers some troubleshooting tips.
 
 [[network-routing-default]]
 === Routing Basics
 
 To view the routing table of a FreeBSD system, use man:netstat[1]:
 
 [source,shell]
 ....
 % netstat -r
 Routing tables
 
 Internet:
 Destination      Gateway            Flags     Refs     Use     Netif Expire
 default          outside-gw         UGS        37      418       em0
 localhost        localhost          UH          0      181       lo0
 test0            0:e0:b5:36:cf:4f   UHLW        5    63288       re0     77
 10.20.30.255     link#1             UHLW        1     2421
 example.com      link#1             UC          0        0
 host1            0:e0:a8:37:8:1e    UHLW        3     4601       lo0
 host2            0:e0:a8:37:8:1e    UHLW        0        5       lo0 =>
 host2.example.com link#1            UC          0        0
 224              link#1             UC          0        0
 ....
 
 The entries in this example are as follows:
 
 default::
 The first route in this table specifies the `default` route.
 When the local system needs to make a connection to a remote host, it checks the routing table to determine if a known path exists.
 If the remote host matches an entry in the table, the system checks to see if it can connect using the interface specified in that entry.
 +
 If the destination does not match an entry, or if all known paths fail, the system uses the entry for the default route.
 For hosts on a local area network, the `Gateway` field in the default route is set to the system which has a direct connection to the Internet.
 When reading this entry, verify that the `Flags` column indicates that the gateway is usable (`UG`).
 +
 The default route for a machine which itself is functioning as the gateway to the outside world will be the gateway machine at the Internet Service Provider (ISP).
 
 localhost::
 The second route is the `localhost` route.
 The interface specified in the `Netif` column for `localhost` is [.filename]#lo0#, also known as the loopback device.
 This indicates that all traffic for this destination should be internal, rather than sending it out over the network.
 
 MAC address::
 The addresses beginning with `0:e0:` are MAC addresses.
 FreeBSD will automatically identify any hosts, `test0` in the example, on the local Ethernet and add a route for that host over the Ethernet interface, [.filename]#re0#.
 This type of route has a timeout, seen in the `Expire` column, which is used if the host does not respond in a specific amount of time.
 When this happens, the route to this host will be automatically deleted.
 These hosts are identified using the Routing Information Protocol (RIP), which calculates routes to local hosts based upon a shortest path determination.
 
 subnet::
 FreeBSD will automatically add subnet routes for the local subnet.
 In this example, `10.20.30.255` is the broadcast address for the subnet `10.20.30` and `example.com` is the domain name associated with that subnet. 
 The designation `link#1` refers to the first Ethernet card in the machine.
 +
 Local network hosts and local subnets have their routes automatically configured by a daemon called man:routed[8].
 If it is not running, only routes which are statically defined by the administrator will exist.
 
 host::
 The `host1` line refers to the host by its Ethernet address.
 Since it is the sending host, FreeBSD knows to use the loopback interface ([.filename]#lo0#) rather than the Ethernet interface.
 +
 The two `host2` lines represent aliases which were created using man:ifconfig[8].
 The `=>` symbol after the [.filename]#lo0# interface says that an alias has been set in addition to the loopback address.
 Such routes only show up on the host that supports the alias and all other hosts on the local network will have a `link#1` line for such routes.
 
 224::
 The final line (destination subnet `224`) deals with multicasting.
 
 Various attributes of each route can be seen in the `Flags` column.
 <<routeflags>> summarizes some of these flags and their meanings:
 
 [[routeflags]]
 .Commonly Seen Routing Table Flags
 [cols="1,1", frame="none", options="header"]
 |===
 | Command
 | Purpose
 
 |U
 |The route is active (up).
 
 |H
 |The route destination is a single host.
 
 |G
 |Send anything for this destination on to this gateway, which will figure out from there where to send it.
 
 |S
 |This route was statically configured.
 
 |C
 |Clones a new route based upon this route for machines to connect to. This type of route is normally used for local networks.
 
 |W
 |The route was auto-configured based upon a local area network (clone) route.
 
 |L
 |Route involves references to Ethernet (link) hardware.
 |===
 
 On a FreeBSD system, the default route can defined in [.filename]#/etc/rc.conf# by specifying the IP address of the default gateway:
 
 [.programlisting]
 ....
 defaultrouter="10.20.30.1"
 ....
 
 It is also possible to manually add the route using `route`:
 
 [source,shell]
 ....
 # route add default 10.20.30.1
 ....
 
 Note that manually added routes will not survive a reboot.
 For more information on manual manipulation of network routing tables, refer to man:route[8].
 
 [[network-static-routes]]
 === Configuring a Router with Static Routes
 
 A FreeBSD system can be configured as the default gateway, or router, for a network if it is a dual-homed system.
 A dual-homed system is a host which resides on at least two different networks.
 Typically, each network is connected to a separate network interface, though IP aliasing can be used to bind multiple addresses, each on a different subnet, to one physical interface.
 
 In order for the system to forward packets between interfaces, FreeBSD must be configured as a router.
 Internet standards and good engineering practice prevent the FreeBSD Project from enabling this feature by default, but it can be configured to start at boot by adding this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 gateway_enable="YES"          # Set to YES if this host will be a gateway
 ....
 
 To enable routing now, set the man:sysctl[8] variable `net.inet.ip.forwarding` to `1`.
 To stop routing, reset this variable to `0`.
 
 The routing table of a router needs additional routes so it knows how to reach other networks.
 Routes can be either added manually using static routes or routes can be automatically learned using a routing protocol.
 Static routes are appropriate for small networks and this section describes how to add a static routing entry for a small network.
 
 [NOTE]
 ====
 For large networks, static routes quickly become unscalable.
 FreeBSD comes with the standard BSD routing daemon man:routed[8], which provides the routing protocols RIP, versions 1 and 2, and IRDP.
 Support for the BGP and OSPF routing protocols can be installed using the package:net/zebra[] package or port.
 ====
 
 Consider the following network:
 
 image::static-routes.png[]
 
 In this scenario, `RouterA` is a FreeBSD machine that is acting as a router to the rest of the Internet.
 It has a default route set to `10.0.0.1` which allows it to connect with the outside world.
 `RouterB` is already configured to use `192.168.1.1` as its default gateway.
 
 Before adding any static routes, the routing table on `RouterA` looks like this:
 
 [source,shell]
 ....
 % netstat -nr
 Routing tables
 
 Internet:
 Destination        Gateway            Flags    Refs      Use  Netif  Expire
 default            10.0.0.1           UGS         0    49378    xl0
 127.0.0.1          127.0.0.1          UH          0        6    lo0
 10.0.0.0/24        link#1             UC          0        0    xl0
 192.168.1.0/24     link#2             UC          0        0    xl1
 ....
 
 With the current routing table, `RouterA` does not have a route to the `192.168.2.0/24` network.
 The following command adds the `Internal Net 2` network to ``RouterA``'s routing table using `192.168.1.2` as the next hop:
 
 [source,shell]
 ....
 # route add -net 192.168.2.0/24 192.168.1.2
 ....
 
 Now, `RouterA` can reach any host on the `192.168.2.0/24` network.
 However, the routing information will not persist if the FreeBSD system reboots.
 If a static route needs to be persistent, add it to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 # Add Internal Net 2 as a persistent static route
 static_routes="internalnet2"
 route_internalnet2="-net 192.168.2.0/24 192.168.1.2"
 ....
 
 The `static_routes` configuration variable is a list of strings separated by a space, where each string references a route name.
 The variable `route_internalnet2` contains the static route for that route name.
 
 Using more than one string in `static_routes` creates multiple static routes.
 The following shows an example of adding static routes for the `192.168.0.0/24` and `192.168.1.0/24` networks:
 
 [.programlisting]
 ....
 static_routes="net1 net2"
 route_net1="-net 192.168.0.0/24 192.168.0.1"
 route_net2="-net 192.168.1.0/24 192.168.1.1"
 ....
 
 [[network-routing-troubleshooting]]
 === Troubleshooting
 
 When an address space is assigned to a network, the service provider configures their routing tables so that all traffic for the network will be sent to the link for the site.
 But how do external sites know to send their packets to the network's ISP?
 
 There is a system that keeps track of all assigned address spaces and defines their point of connection to the Internet backbone, or the main trunk lines that carry Internet traffic across the country and around the world.
 Each backbone machine has a copy of a master set of tables, which direct traffic for a particular network to a specific backbone carrier, and from there down the chain of service providers until it reaches a particular network.
 
 It is the task of the service provider to advertise to the backbone sites that they are the point of connection, and thus the path inward, for a site.
 This is known as route propagation.
 
 Sometimes, there is a problem with route propagation and some sites are unable to connect.
 Perhaps the most useful command for trying to figure out where routing is breaking down is `traceroute`.
 It is useful when `ping` fails.
 
 When using `traceroute`, include the address of the remote host to connect to.
 The output will show the gateway hosts along the path of the attempt, eventually either reaching the target host, or terminating because of a lack of connection.
 For more information, refer to man:traceroute[8].
 
 [[network-routing-multicast]]
 === Multicast Considerations
 
 FreeBSD natively supports both multicast applications and multicast routing.
 Multicast applications do not require any special configuration in order to run on FreeBSD.
 Support for multicast routing requires that the following option be compiled into a custom kernel:
 
 [.programlisting]
 ....
 options MROUTING
 ....
 
 The multicast routing daemon, mrouted can be installed using the package:net/mrouted[] package or port.
 This daemon implements the DVMRP multicast routing protocol and is configured by editing [.filename]#/usr/local/etc/mrouted.conf# in order to set up the tunnels and DVMRP.
 The installation of mrouted also installs map-mbone and mrinfo, as well as their associated man pages.
 Refer to these for configuration examples.
 
 [NOTE]
 ====
 DVMRP has largely been replaced by the PIM protocol in many multicast installations.
 Refer to man:pim[4] for more information.
 ====
 
 [[network-wireless]]
 == Wireless Networking
 
 === Wireless Networking Basics
 
 Most wireless networks are based on the IEEE(R) 802.11 standards.
 A basic wireless network consists of multiple stations communicating with radios that broadcast in either the 2.4GHz or 5GHz band, though this varies according to the locale and is also changing to enable communication in the 2.3GHz and 4.9GHz ranges.
 
 802.11 networks are organized in two ways.
 In _infrastructure mode_, one station acts as a master with all the other stations associating to it, the network is known as a BSS, and the master station is termed an access point (AP).
 In a BSS, all communication passes through the AP; even when one station wants to communicate with another wireless station, messages must go through the AP.
 In the second form of network, there is no master and stations communicate directly.
 This form of network is termed an IBSS and is commonly known as an _ad-hoc network_.
 
 802.11 networks were first deployed in the 2.4GHz band using protocols defined by the IEEE(R) 802.11 and 802.11b standard.
 These specifications include the operating frequencies and the MAC layer characteristics, including framing and transmission rates, as communication can occur at various rates.
 Later, the 802.11a standard defined operation in the 5GHz band, including different signaling mechanisms and higher transmission rates.
 Still later, the 802.11g standard defined the use of 802.11a signaling and transmission mechanisms in the 2.4GHz band in such a way as to be backwards compatible with 802.11b networks.
 
 Separate from the underlying transmission techniques, 802.11 networks have a variety of security mechanisms.
 The original 802.11 specifications defined a simple security protocol called WEP.
 This protocol uses a fixed pre-shared key and the RC4 cryptographic cipher to encode data transmitted on a network.
 Stations must all agree on the fixed key in order to communicate.
 This scheme was shown to be easily broken and is now rarely used except to discourage transient users from joining networks.
 Current security practice is given by the IEEE(R) 802.11i specification that defines new cryptographic ciphers and an additional protocol to authenticate stations to an access point and exchange keys for data communication.
 Cryptographic keys are periodically refreshed and there are mechanisms for detecting and countering intrusion attempts.
 Another security protocol specification commonly used in wireless networks is termed WPA, which was a precursor to 802.11i.
 WPA specifies a subset of the requirements found in 802.11i and is designed for implementation on legacy hardware.
 Specifically, WPA requires only the TKIP cipher that is derived from the original WEP cipher.
 802.11i permits use of TKIP but also requires support for a stronger cipher, AES-CCM, for encrypting data.
 The AES cipher was not required in WPA because it was deemed too computationally costly to be implemented on legacy hardware.
 
 The other standard to be aware of is 802.11e. It defines protocols for deploying multimedia applications, such as streaming video and voice over IP (VoIP), in an 802.11 network.
 Like 802.11i, 802.11e also has a precursor specification termed WME (later renamed WMM) that has been defined by an industry group as a subset of 802.11e that can be deployed now to enable multimedia applications while waiting for the final ratification of 802.11e.
 The most important thing to know about 802.11e and WME/WMM is that it enables prioritized traffic over a wireless network through Quality of Service (QoS) protocols and enhanced media access protocols.
 Proper implementation of these protocols enables high speed bursting of data and prioritized traffic flow.
 
 FreeBSD supports networks that operate using 802.11a, 802.11b, and 802.11g.
 The WPA and 802.11i security protocols are likewise supported (in conjunction with any of 11a, 11b, and 11g) and QoS and traffic prioritization required by the WME/WMM protocols are supported for a limited set of wireless devices.
 
 [[network-wireless-quick-start]]
 === Quick Start
 
 Connecting a computer to an existing wireless network is a very common situation.
 This procedure shows the steps required.
 
 [.procedure]
 . Obtain the SSID (Service Set Identifier) and PSK (Pre-Shared Key) for the wireless network from the network administrator.
 . Identify the wireless adapter. The FreeBSD [.filename]#GENERIC# kernel includes drivers for many common wireless adapters. If the wireless adapter is one of those models, it will be shown in the output from man:ifconfig[8]:
 +
 [source,shell]
 ....
 % ifconfig | grep -B3 -i wireless
 ....
-+ 
++
 On FreeBSD 11 or higher, use this command instead:
 +
 [source,shell]
 ....
 % sysctl net.wlan.devices
 ....
-+ 
++
 If a wireless adapter is not listed, an additional kernel module might be required, or it might be a model not supported by FreeBSD.
-+ 
++
 This example shows the Atheros `ath0` wireless adapter.
 . Add an entry for this network to [.filename]#/etc/wpa_supplicant.conf#. If the file does not exist, create it. Replace _myssid_ and _mypsk_ with the SSID and PSK provided by the network administrator.
 +
 [.programlisting]
 ....
 network={
 	ssid="myssid"
 	psk="mypsk"
 }
 ....
 
 . Add entries to [.filename]#/etc/rc.conf# to configure the network on startup:
 +
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="WPA SYNCDHCP"
 ....
 
 . Restart the computer, or restart the network service to connect to the network:
 +
 [source,shell]
 ....
 # service netif restart
 ....
 
 [[network-wireless-basic]]
 === Basic Setup
 
 ==== Kernel Configuration
 
 To use wireless networking, a wireless networking card is needed and the kernel needs to be configured with the appropriate wireless networking support. 
 The kernel is separated into multiple modules so that only the required support needs to be configured.
 
 The most commonly used wireless devices are those that use parts made by Atheros.
 These devices are supported by man:ath[4] and require the following line to be added to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 if_ath_load="YES"
 ....
 
 The Atheros driver is split up into three separate pieces: the driver (man:ath[4]), the hardware support layer that handles chip-specific functions (man:ath_hal[4]), and an algorithm for selecting the rate for transmitting frames.
 When this support is loaded as kernel modules, any dependencies are automatically handled.
 To load support for a different type of wireless device, specify the module for that device.
 This example is for devices based on the Intersil Prism parts (man:wi[4]) driver:
 
 [.programlisting]
 ....
 if_wi_load="YES"
 ....
 
 [NOTE]
 ====
 The examples in this section use an man:ath[4] device and the device name in the examples must be changed according to the configuration.
 A list of available wireless drivers and supported adapters can be found in the FreeBSD Hardware Notes, available on the https://www.FreeBSD.org/releases/[Release Information] page of the FreeBSD website.
 If a native FreeBSD driver for the wireless device does not exist, it may be possible to use the Windows(R) driver with the help of the crossref:config[config-network-ndis,NDIS] driver wrapper.
 ====
 
 In addition, the modules that implement cryptographic support for the security protocols to use must be loaded.
 These are intended to be dynamically loaded on demand by the man:wlan[4] module, but for now they must be manually configured.
 The following modules are available: man:wlan_wep[4], man:wlan_ccmp[4], and man:wlan_tkip[4].
 The man:wlan_ccmp[4] and man:wlan_tkip[4] drivers are only needed when using the WPA or 802.11i security protocols.
 If the network does not use encryption, man:wlan_wep[4] support is not needed.
 To load these modules at boot time, add the following lines to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 wlan_wep_load="YES"
 wlan_ccmp_load="YES"
 wlan_tkip_load="YES"
 ....
 
 Once this information has been added to [.filename]#/boot/loader.conf#, reboot the FreeBSD box.
 Alternately, load the modules by hand using man:kldload[8].
 
 [NOTE]
 ====
 For users who do not want to use modules, it is possible to compile these drivers into the kernel by adding the following lines to a custom kernel configuration file:
 
 [.programlisting]
 ....
 device wlan              # 802.11 support
 device wlan_wep          # 802.11 WEP support
 device wlan_ccmp         # 802.11 CCMP support
 device wlan_tkip         # 802.11 TKIP support
 device wlan_amrr         # AMRR transmit rate control algorithm
 device ath               # Atheros pci/cardbus NIC's
 device ath_hal           # pci/cardbus chip support
 options AH_SUPPORT_AR5416 # enable AR5416 tx/rx descriptors
 device ath_rate_sample   # SampleRate tx rate control for ath
 ....
 
 With this information in the kernel configuration file, recompile the kernel and reboot the FreeBSD machine.
 ====
 
 Information about the wireless device should appear in the boot messages, like this:
 
 [source,shell]
 ....
 ath0: <Atheros 5212> mem 0x88000000-0x8800ffff irq 11 at device 0.0 on cardbus1
 ath0: [ITHREAD]
 ath0: AR2413 mac 7.9 RF2413 phy 4.5
 ....
 
 ==== Setting the Correct Region
 
 Since the regulatory situation is different in various parts of the world, it is necessary to correctly set the domains that apply to your location to have the correct information about what channels can be used.
 
 The available region definitions can be found in [.filename]#/etc/regdomain.xml#.
 To set the data at runtime, use `ifconfig`:
 
 [source,shell]
 ....
 # ifconfig wlan0 regdomain ETSI country AT
 ....
 
 To persist the settings, add it to [.filename]#/etc/rc.conf#:
 
 [source,shell]
 ....
 # sysrc create_args_wlan0="country AT regdomain ETSI"
 ....
 
 === Infrastructure Mode
 
 Infrastructure (BSS) mode is the mode that is typically used.
 In this mode, a number of wireless access points are connected to a wired network.
 Each wireless network has its own name, called the SSID.
 Wireless clients connect to the wireless access points.
 
 ==== FreeBSD Clients
 
 ===== How to Find Access Points
 
 To scan for available networks, use man:ifconfig[8].
 This request may take a few moments to complete as it requires the system to switch to each available wireless frequency and probe for available access points.
 Only the superuser can initiate a scan:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0
 # ifconfig wlan0 up scan
 SSID/MESH ID    BSSID              CHAN RATE   S:N     INT CAPS
 dlinkap         00:13:46:49:41:76   11   54M -90:96   100 EPS  WPA WME
 freebsdap       00:11:95:c3:0d:ac    1   54M -83:96   100 EPS  WPA
 ....
 
 [NOTE]
 ====
 The interface must be `up` before it can scan.
 Subsequent scan requests do not require the interface to be marked as up again.
 ====
 
 The output of a scan request lists each BSS/IBSS network found.
 Besides listing the name of the network, the `SSID`, the output also shows the `BSSID`, which is the MAC address of the access point.
 The `CAPS` field identifies the type of each network and the capabilities of the stations operating there:
 
 .Station Capability Codes
 [cols="1,1", frame="none", options="header"]
 |===
 | Capability Code
 | Meaning
 
 |`E`
 |Extended Service Set (ESS). Indicates that the station is part of an infrastructure network rather than an IBSS/ad-hoc network.
 
 |`I`
 |IBSS/ad-hoc network. Indicates that the station is part of an ad-hoc network rather than an ESS network.
 
 |`P`
 |Privacy. Encryption is required for all data frames exchanged within the BSS using cryptographic means such as WEP, TKIP or AES-CCMP.
 
 |`S`
 |Short Preamble. Indicates that the network is using short preambles, defined in 802.11b High Rate/DSSS PHY, and utilizes a 56 bit sync field rather than the 128 bit field used in long preamble mode.
 
 |`s`
 |Short slot time. Indicates that the 802.11g network is using a short slot time because there are no legacy (802.11b) stations present.
 |===
 
 One can also display the current list of known networks with:
 
 [source,shell]
 ....
 # ifconfig wlan0 list scan
 ....
 
 This information may be updated automatically by the adapter or manually with a `scan` request.
 Old data is automatically removed from the cache, so over time this list may shrink unless more scans are done.
 
 ===== Basic Settings
 
 This section provides a simple example of how to make the wireless network adapter work in FreeBSD without encryption.
 Once familiar with these concepts, it is strongly recommend to use <<network-wireless-wpa,WPA>> to set up the wireless network.
 
 There are three basic steps to configure a wireless network: select an access point, authenticate the station, and configure an IP address.
 The following sections discuss each step.
 
 ====== Selecting an Access Point
 
 Most of the time, it is sufficient to let the system choose an access point using the builtin heuristics.
 This is the default behavior when an interface is marked as up or it is listed in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="DHCP"
 ....
 
 If there are multiple access points, a specific one can be selected by its SSID:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="ssid your_ssid_here DHCP"
 ....
 
 In an environment where there are multiple access points with the same SSID, which is often done to simplify roaming, it may be necessary to associate to one specific device.
 In this case, the BSSID of the access point can be specified, with or without the SSID:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="ssid your_ssid_here bssid xx:xx:xx:xx:xx:xx DHCP"
 ....
 
 There are other ways to constrain the choice of an access point, such as limiting the set of frequencies the system will scan on.
 This may be useful for a multi-band wireless card as scanning all the possible channels can be time-consuming.
 To limit operation to a specific band, use the `mode` parameter:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="mode 11g ssid your_ssid_here DHCP"
 ....
 
 This example will force the card to operate in 802.11g, which is defined only for 2.4GHz frequencies so any 5GHz channels will not be considered.
 This can also be achieved with the `channel` parameter, which locks operation to one specific frequency, and the `chanlist` parameter, to specify a list of channels for scanning.
 More information about these parameters can be found in man:ifconfig[8].
 
 ====== Authentication
 
 Once an access point is selected, the station needs to authenticate before it can pass data.
 Authentication can happen in several ways.
 The most common scheme, open authentication, allows any station to join the network and communicate.
 This is the authentication to use for test purposes the first time a wireless network is setup.
 Other schemes require cryptographic handshakes to be completed before data traffic can flow, either using pre-shared keys or secrets, or more complex schemes that involve backend services such as RADIUS.
 Open authentication is the default setting.
 The next most common setup is WPA-PSK, also known as WPA Personal, which is described in <<network-wireless-wpa-wpa-psk>>.
 
 [NOTE]
 ====
 If using an Apple(R) AirPort(R) Extreme base station for an access point, shared-key authentication together with a WEP key needs to be configured.
 This can be configured in [.filename]#/etc/rc.conf# or by using man:wpa_supplicant[8].
 For a single AirPort(R) base station, access can be configured with:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="authmode shared wepmode on weptxkey 1 wepkey 01234567 DHCP"
 ....
 
 In general, shared key authentication should be avoided because it uses the WEP key material in a highly-constrained manner, making it even easier to crack the key.
 If WEP must be used for compatibility with legacy devices, it is better to use WEP with `open` authentication.
 More information regarding WEP can be found in <<network-wireless-wep>>.
 ====
 
 ====== Getting an IP Address with DHCP
 
 Once an access point is selected and the authentication parameters are set, an IP address must be obtained in order to communicate.
 Most of the time, the IP address is obtained via DHCP.
 To achieve that, edit [.filename]#/etc/rc.conf# and add `DHCP` to the configuration for the device:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="DHCP"
 ....
 
 The wireless interface is now ready to bring up:
 
 [source,shell]
 ....
 # service netif start
 ....
 
 Once the interface is running, use man:ifconfig[8] to see the status of the interface [.filename]#ath0#:
 
 [source,shell]
 ....
 # ifconfig wlan0
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         ether 00:11:95:d5:43:62
         inet 192.168.1.100 netmask 0xffffff00 broadcast 192.168.1.255
         media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g
         status: associated
         ssid dlinkap channel 11 (2462 Mhz 11g) bssid 00:13:46:49:41:76
         country US ecm authmode OPEN privacy OFF txpower 21.5 bmiss 7
         scanvalid 60 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7
         roam:rate 5 protmode CTS wme burst
 ....
 
 The `status: associated` line means that it is connected to the wireless network.
 The `bssid 00:13:46:49:41:76` is the MAC address of the access point and `authmode OPEN` indicates that the communication is not encrypted.
 
 ====== Static IP Address
 
 If an IP address cannot be obtained from a DHCP server, set a fixed IP address.
 Replace the `DHCP` keyword shown above with the address information.
 Be sure to retain any other parameters for selecting the access point:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="inet 192.168.1.100 netmask 255.255.255.0 ssid your_ssid_here"
 ....
 
 [[network-wireless-wpa]]
 ===== WPA
 
 Wi-Fi Protected Access (WPA) is a security protocol used together with 802.11 networks to address the lack of proper authentication and the weakness of WEP.
 WPA leverages the 802.1X authentication protocol and uses one of several ciphers instead of WEP for data integrity.
 The only cipher required by WPA is the Temporary Key Integrity Protocol (TKIP).
 TKIP is a cipher that extends the basic RC4 cipher used by WEP by adding integrity checking, tamper detection, and measures for responding to detected intrusions.
 TKIP is designed to work on legacy hardware with only software modification.
 It represents a compromise that improves security but is still not entirely immune to attack.
 WPA also specifies the AES-CCMP cipher as an alternative to TKIP, and that is preferred when possible.
 For this specification, the term WPA2 or RSN is commonly used.
 
 WPA defines authentication and encryption protocols.
 Authentication is most commonly done using one of two techniques: by 802.1X and a backend authentication service such as RADIUS, or by a minimal handshake between the station and the access point using a pre-shared secret.
 The former is commonly termed WPA Enterprise and the latter is known as WPA Personal.
 Since most people will not set up a RADIUS backend server for their wireless network, WPA-PSK is by far the most commonly encountered configuration for WPA.
 
 The control of the wireless connection and the key negotiation or authentication with a server is done using man:wpa_supplicant[8].
 This program requires a configuration file, [.filename]#/etc/wpa_supplicant.conf#, to run.
 More information regarding this file can be found in man:wpa_supplicant.conf[5].
 
 [[network-wireless-wpa-wpa-psk]]
 ====== WPA-PSK
 
 WPA-PSK, also known as WPA Personal, is based on a pre-shared key (PSK) which is generated from a given password and used as the master key in the wireless network.
 This means every wireless user will share the same key.
 WPA-PSK is intended for small networks where the use of an authentication server is not possible or desired.
 
 [WARNING]
 ====
 Always use strong passwords that are sufficiently long and made from a rich alphabet so that they will not be easily guessed or attacked.
 ====
 
 The first step is the configuration of [.filename]#/etc/wpa_supplicant.conf# with the SSID and the pre-shared key of the network:
 
 [.programlisting]
 ....
 network={
   ssid="freebsdap"
   psk="freebsdmall"
 }
 ....
 
 Then, in [.filename]#/etc/rc.conf#, indicate that the wireless device configuration will be done with WPA and the IP address will be obtained with DHCP:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="WPA DHCP"
 ....
 
 Then, bring up the interface:
 
 [source,shell]
 ....
 # service netif start
 Starting wpa_supplicant.
 DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
 DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 6
 DHCPOFFER from 192.168.0.1
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67
 DHCPACK from 192.168.0.1
 bound to 192.168.0.254 -- renewal in 300 seconds.
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       ether 00:11:95:d5:43:62
       inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
       media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g
       status: associated
       ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
       country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
       AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
       bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
       wme burst roaming MANUAL
 ....
 
 Or, try to configure the interface manually using the information in [.filename]#/etc/wpa_supplicant.conf#:
 
 [source,shell]
 ....
 # wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf
 Trying to associate with 00:11:95:c3:0d:ac (SSID='freebsdap' freq=2412 MHz)
 Associated with 00:11:95:c3:0d:ac
 WPA: Key negotiation completed with 00:11:95:c3:0d:ac [PTK=CCMP GTK=CCMP]
 CTRL-EVENT-CONNECTED - Connection to 00:11:95:c3:0d:ac completed (auth) [id=0 id_str=]
 ....
 
 The next operation is to launch man:dhclient[8] to get the IP address from the DHCP server:
 
 [source,shell]
 ....
 # dhclient wlan0
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67
 DHCPACK from 192.168.0.1
 bound to 192.168.0.254 -- renewal in 300 seconds.
 # ifconfig wlan0
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       ether 00:11:95:d5:43:62
       inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
       media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g
       status: associated
       ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
       country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
       AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
       bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
       wme burst roaming MANUAL
 ....
 
 [NOTE]
 ====
 If [.filename]#/etc/rc.conf# has an `ifconfig_wlan0="DHCP"` entry, man:dhclient[8] will be launched automatically after man:wpa_supplicant[8] associates with the access point.
 ====
 
 If DHCP is not possible or desired, set a static IP address after man:wpa_supplicant[8] has authenticated the station:
 
 [source,shell]
 ....
 # ifconfig wlan0 inet 192.168.0.100 netmask 255.255.255.0
 # ifconfig wlan0
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       ether 00:11:95:d5:43:62
       inet 192.168.0.100 netmask 0xffffff00 broadcast 192.168.0.255
       media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g
       status: associated
       ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
       country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
       AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
       bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
       wme burst roaming MANUAL
 ....
 
 When DHCP is not used, the default gateway and the nameserver also have to be manually set:
 
 [source,shell]
 ....
 # route add default your_default_router
 # echo "nameserver your_DNS_server" >> /etc/resolv.conf
 ....
 
 [[network-wireless-wpa-eap-tls]]
 ====== WPA with EAP-TLS
 
 The second way to use WPA is with an 802.1X backend authentication server.
 In this case, WPA is called WPA Enterprise to differentiate it from the less secure WPA Personal.
 Authentication in WPA Enterprise is based on the Extensible Authentication Protocol (EAP).
 
 EAP does not come with an encryption method.
 Instead, EAP is embedded inside an encrypted tunnel.
 There are many EAP authentication methods, but EAP-TLS, EAP-TTLS, and EAP-PEAP are the most common.
 
 EAP with Transport Layer Security (EAP-TLS) is a well-supported wireless authentication protocol since it was the first EAP method to be certified by the http://www.wi-fi.org/[Wi-Fi Alliance].
 EAP-TLS requires three certificates to run: the certificate of the Certificate Authority (CA) installed on all machines, the server certificate for the authentication server, and one client certificate for each wireless client.
 In this EAP method, both the authentication server and wireless client authenticate each other by presenting their respective certificates, and then verify that these certificates were signed by the organization's CA.
 
 As previously, the configuration is done via [.filename]#/etc/wpa_supplicant.conf#:
 
 [.programlisting]
 ....
 network={
   ssid="freebsdap" <.>
   proto=RSN  <.>
   key_mgmt=WPA-EAP <.>
   eap=TLS <.>
   identity="loader" <.>
   ca_cert="/etc/certs/cacert.pem" <.>
   client_cert="/etc/certs/clientcert.pem" <.>
   private_key="/etc/certs/clientkey.pem" <.>
   private_key_passwd="freebsdmallclient" <.>
 }
 ....
 
 <.> This field indicates the network name (SSID).
 <.> This example uses the RSN IEEE(R) 802.11i protocol, also known as WPA2.
 <.> The `key_mgmt` line refers to the key management protocol to use. In this example, it is WPA using EAP authentication.
 <.> This field indicates the EAP method for the connection.
 <.> The `identity` field contains the identity string for EAP.
 <.> The `ca_cert` field indicates the pathname of the CA certificate file. This file is needed to verify the server certificate.
 <.> The `client_cert` line gives the pathname to the client certificate file. This certificate is unique to each wireless client of the network.
 <.> The `private_key` field is the pathname to the client certificate private key file.
 <.> The `private_key_passwd` field contains the passphrase for the private key.
 
 Then, add the following lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="WPA DHCP"
 ....
 
 The next step is to bring up the interface:
 
 [source,shell]
 ....
 # service netif start
 Starting wpa_supplicant.
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15
 DHCPACK from 192.168.0.20
 bound to 192.168.0.254 -- renewal in 300 seconds.
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       ether 00:11:95:d5:43:62
       inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
       media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g
       status: associated
       ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
       country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
       AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
       bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
       wme burst roaming MANUAL
 ....
 
 It is also possible to bring up the interface manually using man:wpa_supplicant[8] and man:ifconfig[8].
 
 [[network-wireless-wpa-eap-ttls]]
 ====== WPA with EAP-TTLS
 
 With EAP-TLS, both the authentication server and the client need a certificate.
 With EAP-TTLS, a client certificate is optional.
 This method is similar to a web server which creates a secure SSL tunnel even if visitors do not have client-side certificates.
 EAP-TTLS uses an encrypted TLS tunnel for safe transport of the authentication data.
 
 The required configuration can be added to [.filename]#/etc/wpa_supplicant.conf#:
 
 [.programlisting]
 ....
 network={
   ssid="freebsdap"
   proto=RSN
   key_mgmt=WPA-EAP
   eap=TTLS <.>
   identity="test" <.>
   password="test" <.>
   ca_cert="/etc/certs/cacert.pem" <.>
   phase2="auth=MD5" <.>
 }
 ....
 
 <.> This field specifies the EAP method for the connection.
 <.> The `identity` field contains the identity string for EAP authentication inside the encrypted TLS tunnel.
 <.> The `password` field contains the passphrase for the EAP authentication.
 <.> The `ca_cert` field indicates the pathname of the CA certificate file. This file is needed to verify the server certificate.
 <.> This field specifies the authentication method used in the encrypted TLS tunnel. In this example, EAP with MD5-Challenge is used. The "inner authentication" phase is often called "phase2".
 
 Next, add the following lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="WPA DHCP"
 ....
 
 The next step is to bring up the interface:
 
 [source,shell]
 ....
 # service netif start
 Starting wpa_supplicant.
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 21
 DHCPACK from 192.168.0.20
 bound to 192.168.0.254 -- renewal in 300 seconds.
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       ether 00:11:95:d5:43:62
       inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
       media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g
       status: associated
       ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
       country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
       AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
       bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
       wme burst roaming MANUAL
 ....
 
 [[network-wireless-wpa-eap-peap]]
 ====== WPA with EAP-PEAP
 
 [NOTE]
 ====
 PEAPv0/EAP-MSCHAPv2 is the most common PEAP method.
 In this chapter, the term PEAP is used to refer to that method.
 ====
 
 Protected EAP (PEAP) is designed as an alternative to EAP-TTLS and is the most used EAP standard after EAP-TLS.
 In a network with mixed operating systems, PEAP should be the most supported standard after EAP-TLS.
 
 PEAP is similar to EAP-TTLS as it uses a server-side certificate to authenticate clients by creating an encrypted TLS tunnel between the client and the authentication server, which protects the ensuing exchange of authentication information.
 PEAP authentication differs from EAP-TTLS as it broadcasts the username in the clear and only the password is sent in the encrypted TLS tunnel.
 EAP-TTLS will use the TLS tunnel for both the username and password.
 
 Add the following lines to [.filename]#/etc/wpa_supplicant.conf# to configure the EAP-PEAP related settings:
 
 [.programlisting]
 ....
 network={
   ssid="freebsdap"
   proto=RSN
   key_mgmt=WPA-EAP
   eap=PEAP <.>
   identity="test" <.>
   password="test" <.>
   ca_cert="/etc/certs/cacert.pem" <.>
   phase1="peaplabel=0" <.>
   phase2="auth=MSCHAPV2" <.>
 }
 ....
 
 <.> This field specifies the EAP method for the connection.
 <.> The `identity` field contains the identity string for EAP authentication inside the encrypted TLS tunnel.
 <.> The `password` field contains the passphrase for the EAP authentication.
 <.> The `ca_cert` field indicates the pathname of the CA certificate file. This file is needed to verify the server certificate.
 <.> This field contains the parameters for the first phase of authentication, the TLS tunnel. According to the authentication server used, specify a specific label for authentication. Most of the time, the label will be "client EAP encryption" which is set by using `peaplabel=0`. More information can be found in man:wpa_supplicant.conf[5].
 <.> This field specifies the authentication protocol used in the encrypted TLS tunnel. In the case of PEAP, it is `auth=MSCHAPV2`.
 
 Add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 ifconfig_wlan0="WPA DHCP"
 ....
 
 Then, bring up the interface:
 
 [source,shell]
 ....
 # service netif start
 Starting wpa_supplicant.
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15
 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 21
 DHCPACK from 192.168.0.20
 bound to 192.168.0.254 -- renewal in 300 seconds.
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       ether 00:11:95:d5:43:62
       inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
       media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g
       status: associated
       ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
       country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
       AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
       bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
       wme burst roaming MANUAL
 ....
 
 [[network-wireless-wep]]
 ===== WEP
 
 Wired Equivalent Privacy (WEP) is part of the original 802.11 standard.
 There is no authentication mechanism, only a weak form of access control which is easily cracked.
 
 WEP can be set up using man:ifconfig[8]:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0
 # ifconfig wlan0 inet 192.168.1.100 netmask 255.255.255.0 \
 	    ssid my_net wepmode on weptxkey 3 wepkey 3:0x3456789012
 ....
 
 * The `weptxkey` specifies which WEP key will be used in the transmission. This example uses the third key. This must match the setting on the access point. When unsure which key is used by the access point, try `1` (the first key) for this value.
 * The `wepkey` selects one of the WEP keys. It should be in the format _index:key_. Key `1` is used by default; the index only needs to be set when using a key other than the first key.
 +
 [NOTE]
 ====
 Replace the `0x3456789012` with the key configured for use on the access point.
 ====
 
 Refer to man:ifconfig[8] for further information.
 
 The man:wpa_supplicant[8] facility can be used to configure a wireless interface with WEP.
 The example above can be set up by adding the following lines to [.filename]#/etc/wpa_supplicant.conf#:
 
 [.programlisting]
 ....
 network={
   ssid="my_net"
   key_mgmt=NONE
   wep_key3=3456789012
   wep_tx_keyidx=3
 }
 ....
 
 Then:
 
 [source,shell]
 ....
 # wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf
 Trying to associate with 00:13:46:49:41:76 (SSID='dlinkap' freq=2437 MHz)
 Associated with 00:13:46:49:41:76
 ....
 
 === Ad-hoc Mode
 
 IBSS mode, also called ad-hoc mode, is designed for point to point connections.
 For example, to establish an ad-hoc network between the machines `A` and `B`, choose two IP addresses and a SSID.
 
 On `A`:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0 wlanmode adhoc
 # ifconfig wlan0 inet 192.168.0.1 netmask 255.255.255.0 ssid freebsdap
 # ifconfig wlan0
   wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	  ether 00:11:95:c3:0d:ac
 	  inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
 	  media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <adhoc>
 	  status: running
 	  ssid freebsdap channel 2 (2417 Mhz 11g) bssid 02:11:95:c3:0d:ac
 	  country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60
 	  protmode CTS wme burst
 ....
 
 The `adhoc` parameter indicates that the interface is running in IBSS mode.
 
 `B` should now be able to detect `A`:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0 wlanmode adhoc
 # ifconfig wlan0 up scan
   SSID/MESH ID    BSSID              CHAN RATE   S:N     INT CAPS
   freebsdap       02:11:95:c3:0d:ac    2   54M -64:-96  100 IS   WME
 ....
 
 The `I` in the output confirms that `A` is in ad-hoc mode.
 Now, configure `B` with a different IP address:
 
 [source,shell]
 ....
 # ifconfig wlan0 inet 192.168.0.2 netmask 255.255.255.0 ssid freebsdap
 # ifconfig wlan0
   wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	  ether 00:11:95:d5:43:62
 	  inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
 	  media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <adhoc>
 	  status: running
 	  ssid freebsdap channel 2 (2417 Mhz 11g) bssid 02:11:95:c3:0d:ac
 	  country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60
 	  protmode CTS wme burst
 ....
 
 Both `A` and `B` are now ready to exchange information.
 
 [[network-wireless-ap]]
 === FreeBSD Host Access Points
 
 FreeBSD can act as an Access Point (AP) which eliminates the need to buy a hardware AP or run an ad-hoc network.
 This can be particularly useful when a FreeBSD machine is acting as a gateway to another network such as the Internet.
 
 [[network-wireless-ap-basic]]
 ==== Basic Settings
 
 Before configuring a FreeBSD machine as an AP, the kernel must be configured with the appropriate networking support for the wireless card as well as the security protocols being used.
 For more details, see <<network-wireless-basic>>.
 
 [NOTE]
 ====
 The NDIS driver wrapper for Windows(R) drivers does not currently support AP operation.
 Only native FreeBSD wireless drivers support AP mode.
 ====
 
 Once wireless networking support is loaded, check if the wireless device supports the host-based access point mode, also known as hostap mode:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0
 # ifconfig wlan0 list caps
 drivercaps=6f85edc1<STA,FF,TURBOP,IBSS,HOSTAP,AHDEMO,TXPMGT,SHSLOT,SHPREAMBLE,MONITOR,MBSS,WPA1,WPA2,BURST,WME,WDS,BGSCAN,TXFRAG>
 cryptocaps=1f<WEP,TKIP,AES,AES_CCM,TKIPMIC>
 ....
 
 This output displays the card's capabilities.
 The `HOSTAP` word confirms that this wireless card can act as an AP.
 Various supported ciphers are also listed: WEP, TKIP, and AES.
 This information indicates which security protocols can be used on the AP.
 
 The wireless device can only be put into hostap mode during the creation of the network pseudo-device, so a previously created device must be destroyed first:
 
 [source,shell]
 ....
 # ifconfig wlan0 destroy
 ....
 
 then regenerated with the correct option before setting the other parameters:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0 wlanmode hostap
 # ifconfig wlan0 inet 192.168.0.1 netmask 255.255.255.0 ssid freebsdap mode 11g channel 1
 ....
 
 Use man:ifconfig[8] again to see the status of the [.filename]#wlan0# interface:
 
 [source,shell]
 ....
 # ifconfig wlan0
   wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	  ether 00:11:95:c3:0d:ac
 	  inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
 	  media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <hostap>
 	  status: running
 	  ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
 	  country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60
 	  protmode CTS wme burst dtimperiod 1 -dfs
 ....
 
 The `hostap` parameter indicates the interface is running in the host-based access point mode.
 
 The interface configuration can be done automatically at boot time by adding the following lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 wlans_ath0="wlan0"
 create_args_wlan0="wlanmode hostap"
 ifconfig_wlan0="inet 192.168.0.1 netmask 255.255.255.0 ssid freebsdap mode 11g channel 1"
 ....
 
 ==== Host-based Access Point Without Authentication or Encryption
 
 Although it is not recommended to run an AP without any authentication or encryption, this is a simple way to check if the AP is working.
 This configuration is also important for debugging client issues.
 
 Once the AP is configured, initiate a scan from another wireless machine to find the AP:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0
 # ifconfig wlan0 up scan
 SSID/MESH ID    BSSID              CHAN RATE   S:N     INT CAPS
 freebsdap       00:11:95:c3:0d:ac    1   54M -66:-96  100 ES   WME
 ....
 
 The client machine found the AP and can be associated with it:
 
 [source,shell]
 ....
 # ifconfig wlan0 inet 192.168.0.2 netmask 255.255.255.0 ssid freebsdap
 # ifconfig wlan0
   wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	  ether 00:11:95:d5:43:62
 	  inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
 	  media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g
 	  status: associated
 	  ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
 	  country US ecm authmode OPEN privacy OFF txpower 21.5 bmiss 7
 	  scanvalid 60 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7
 	  roam:rate 5 protmode CTS wme burst
 ....
 
 [[network-wireless-ap-wpa]]
 ==== WPA2 Host-based Access Point
 
 This section focuses on setting up a FreeBSD access point using the WPA2 security protocol.
 More details regarding WPA and the configuration of WPA-based wireless clients can be found in <<network-wireless-wpa>>.
 
 The man:hostapd[8] daemon is used to deal with client authentication and key management on the WPA2-enabled AP.
 
 The following configuration operations are performed on the FreeBSD machine acting as the AP.
 Once the AP is correctly working, man:hostapd[8] can be automatically started at boot with this line in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 hostapd_enable="YES"
 ....
 
 Before trying to configure man:hostapd[8], first configure the basic settings introduced in <<network-wireless-ap-basic>>.
 
 ===== WPA2-PSK
 
 WPA2-PSK is intended for small networks where the use of a backend authentication server is not possible or desired.
 
 The configuration is done in [.filename]#/etc/hostapd.conf#:
 
 [.programlisting]
 ....
 interface=wlan0                  <.>
 debug=1                          <.>
 ctrl_interface=/var/run/hostapd  <.>
 ctrl_interface_group=wheel       <.>
 ssid=freebsdap                   <.>
 wpa=2                            <.>
 wpa_passphrase=freebsdmall       <.>
 wpa_key_mgmt=WPA-PSK             <.>
 wpa_pairwise=CCMP                <.>
 ....
 
 <.> Wireless interface used for the access point.
 <.> Level of verbosity used during the execution of man:hostapd[8]. A value of `1` represents the minimal level.
 <.> Pathname of the directory used by man:hostapd[8] to store domain socket files for communication with external programs such as man:hostapd_cli[8]. The default value is used in this example.
 <.> The group allowed to access the control interface files.
 <.> The wireless network name, or SSID, that will appear in wireless scans.
 <.> Enable WPA and specify which WPA authentication protocol will be required. A value of `2` configures the AP for WPA2 and is recommended. Set to `1` only if the obsolete WPA is required.
 <.> ASCII passphrase for WPA authentication.
 <.> The key management protocol to use. This example sets WPA-PSK.
 <.> Encryption algorithms accepted by the access point. In this example, only the CCMP (AES) cipher is accepted. CCMP is an alternative to TKIP and is strongly preferred when possible. TKIP should be allowed only when there are stations incapable of using CCMP.
 
 The next step is to start man:hostapd[8]:
 
 [source,shell]
 ....
 # service hostapd forcestart
 ....
 
 [source,shell]
 ....
 # ifconfig wlan0
 wlan0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	ether 04:f0:21:16:8e:10
 	inet6 fe80::6f0:21ff:fe16:8e10%wlan0 prefixlen 64 scopeid 0x9
 	nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
 	media: IEEE 802.11 Wireless Ethernet autoselect mode 11na <hostap>
 	status: running
 	ssid No5ignal channel 36 (5180 MHz 11a ht/40+) bssid 04:f0:21:16:8e:10
 	country US ecm authmode WPA2/802.11i privacy MIXED deftxkey 2
 	AES-CCM 2:128-bit AES-CCM 3:128-bit txpower 17 mcastrate 6 mgmtrate 6
 	scanvalid 60 ampdulimit 64k ampdudensity 8 shortgi wme burst
 	dtimperiod 1 -dfs
 	groups: wlan
 ....
 
 Once the AP is running, the clients can associate with it.
 See <<network-wireless-wpa>> for more details.
 It is possible to see the stations associated with the AP using `ifconfig _wlan0_ list sta`.
 
 ==== WEP Host-based Access Point
 
 It is not recommended to use WEP for setting up an AP since there is no authentication mechanism and the encryption is easily cracked.
 Some legacy wireless cards only support WEP and these cards will only support an AP without authentication or encryption.
 
 The wireless device can now be put into hostap mode and configured with the correct SSID and IP address:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0 wlanmode hostap
 # ifconfig wlan0 inet 192.168.0.1 netmask 255.255.255.0 \
 	ssid freebsdap wepmode on weptxkey 3 wepkey 3:0x3456789012 mode 11g
 ....
 
 * The `weptxkey` indicates which WEP key will be used in the transmission. This example uses the third key as key numbering starts with `1`. This parameter must be specified in order to encrypt the data.
 * The `wepkey` sets the selected WEP key. It should be in the format _index:key_. If the index is not given, key `1` is set. The index needs to be set when using keys other than the first key.
 
 Use man:ifconfig[8] to see the status of the [.filename]#wlan0# interface:
 
 [source,shell]
 ....
 # ifconfig wlan0
   wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	  ether 00:11:95:c3:0d:ac
 	  inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
 	  media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <hostap>
 	  status: running
 	  ssid freebsdap channel 4 (2427 Mhz 11g) bssid 00:11:95:c3:0d:ac
 	  country US ecm authmode OPEN privacy ON deftxkey 3 wepkey 3:40-bit
 	  txpower 21.5 scanvalid 60 protmode CTS wme burst dtimperiod 1 -dfs
 ....
 
 From another wireless machine, it is now possible to initiate a scan to find the AP:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0
 # ifconfig wlan0 up scan
 SSID            BSSID              CHAN RATE  S:N   INT CAPS
 freebsdap       00:11:95:c3:0d:ac    1   54M 22:1   100 EPS
 ....
 
 In this example, the client machine found the AP and can associate with it using the correct parameters.
 See <<network-wireless-wep>> for more details.
 
 === Using Both Wired and Wireless Connections
 
 A wired connection provides better performance and reliability, while a wireless connection provides flexibility and mobility.
 Laptop users typically want to roam seamlessly between the two types of connections.
 
 On FreeBSD, it is possible to combine two or even more network interfaces together in a "failover" fashion.
 This type of configuration uses the most preferred and available connection from a group of network interfaces, and the operating system switches automatically when the link state changes.
 
 Link aggregation and failover is covered in <<network-aggregation>> and an example for using both wired and wireless connections is provided at <<networking-lagg-wired-and-wireless>>.
 
 === Troubleshooting
 
 This section describes a number of steps to help troubleshoot common wireless networking problems.
 
 * If the access point is not listed when scanning, check that the configuration has not limited the wireless device to a limited set of channels.
 * If the device cannot associate with an access point, verify that the configuration matches the settings on the access point. This includes the authentication scheme and any security protocols. Simplify the configuration as much as possible. If using a security protocol such as WPA or WEP, configure the access point for open authentication and no security to see if traffic will pass.
-+ 
++
 Debugging support is provided by man:wpa_supplicant[8]. Try running this utility manually with `-dd` and look at the system logs.
 * Once the system can associate with the access point, diagnose the network configuration using tools like man:ping[8].
 * There are many lower-level debugging tools. Debugging messages can be enabled in the 802.11 protocol support layer using man:wlandebug[8]. For example, to enable console messages related to scanning for access points and the 802.11 protocol handshakes required to arrange communication:
 +
 [source,shell]
 ....
 # wlandebug -i wlan0 +scan+auth+debug+assoc
   net.wlan.0.debug: 0 => 0xc80000<assoc,auth,scan>
 ....
-+ 
++
 Many useful statistics are maintained by the 802.11 layer and `wlanstats`, found in [.filename]#/usr/src/tools/tools/net80211#, will dump this information. 
 These statistics should display all errors identified by the 802.11 layer.
 However, some errors are identified in the device drivers that lie below the 802.11 layer so they may not show up.
 To diagnose device-specific problems, refer to the drivers' documentation.
 
 If the above information does not help to clarify the problem, submit a problem report and include output from the above tools.
 
 [[network-usb-tethering]]
 == USB Tethering
 
 Many cellphones provide the option to share their data connection over USB (often called "tethering").
 This feature uses one of RNDIS, CDC, or a custom Apple(R) iPhone(R)/iPad(R) protocol.
 
 * Android(TM) devices generally use the man:urndis[4] driver.
 * Apple(R) devices use the man:ipheth[4] driver.
 * Older devices will often use the man:cdce[4] driver.
 
 Before attaching a device, load the appropriate driver into the kernel:
 
 [source,shell]
 ....
 # kldload if_urndis
 # kldload if_cdce
 # kldload if_ipheth
 ....
 
 Once the device is attached ``ue``_0_ will be available for use like a normal network device.
 Be sure that the "USB tethering" option is enabled on the device.
 
 To make this change permanent and load the driver as a module at boot time, place the appropriate line of the following in [.filename]#/boot/loader.conf#:
 
 [source,shell]
 ....
 if_urndis_load="YES"
 if_cdce_load="YES"
 if_ipheth_load="YES"
 ....
 
 [[network-bluetooth]]
 == Bluetooth
 
 Bluetooth is a wireless technology for creating personal networks operating in the 2.4 GHz unlicensed band, with a range of 10 meters.
 Networks are usually formed ad-hoc from portable devices such as cellular phones, handhelds, and laptops.
 Unlike Wi-Fi wireless technology, Bluetooth offers higher level service profiles, such as FTP-like file servers, file pushing, voice transport, serial line emulation, and more.
 
 This section describes the use of a USB Bluetooth dongle on a FreeBSD system.
 It then describes the various Bluetooth protocols and utilities.
 
 === Loading Bluetooth Support
 
 The Bluetooth stack in FreeBSD is implemented using the man:netgraph[4] framework.
 A broad variety of Bluetooth USB dongles is supported by man:ng_ubt[4].
 Broadcom BCM2033 based Bluetooth devices are supported by the man:ubtbcmfw[4] and man:ng_ubt[4] drivers.
 The 3Com Bluetooth PC Card 3CRWB60-A is supported by the man:ng_bt3c[4] driver.
 Serial and UART based Bluetooth devices are supported by man:sio[4], man:ng_h4[4], and man:hcseriald[8].
 
 Before attaching a device, determine which of the above drivers it uses, then load the driver.
 For example, if the device uses the man:ng_ubt[4] driver:
 
 [source,shell]
 ....
 # kldload ng_ubt
 ....
 
 If the Bluetooth device will be attached to the system during system startup, the system can be configured to load the module at boot time by adding the driver to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 ng_ubt_load="YES"
 ....
 
 Once the driver is loaded, plug in the USB dongle.
 If the driver load was successful, output similar to the following should appear on the console and in [.filename]#/var/log/messages#:
 
 [source,shell]
 ....
 ubt0: vendor 0x0a12 product 0x0001, rev 1.10/5.25, addr 2
 ubt0: Interface 0 endpoints: interrupt=0x81, bulk-in=0x82, bulk-out=0x2
 ubt0: Interface 1 (alt.config 5) endpoints: isoc-in=0x83, isoc-out=0x3,
       wMaxPacketSize=49, nframes=6, buffer size=294
 ....
 
 To start and stop the Bluetooth stack, use its startup script. It is a good idea to stop the stack before unplugging the device.
 Starting the bluetooth stack might require man:hcsecd[8] to be started.
 When starting the stack, the output should be similar to the following:
 
 [source,shell]
 ....
 # service bluetooth start ubt0
 BD_ADDR: 00:02:72:00:d4:1a
 Features: 0xff 0xff 0xf 00 00 00 00 00
 <3-Slot> <5-Slot> <Encryption> <Slot offset>
 <Timing accuracy> <Switch> <Hold mode> <Sniff mode>
 <Park mode> <RSSI> <Channel quality> <SCO link>
 <HV2 packets> <HV3 packets> <u-law log> <A-law log> <CVSD>
 <Paging scheme> <Power control> <Transparent SCO data>
 Max. ACL packet size: 192 bytes
 Number of ACL packets: 8
 Max. SCO packet size: 64 bytes
 Number of SCO packets: 8
 ....
 
 === Finding Other Bluetooth Devices
 
 The Host Controller Interface (HCI) provides a uniform method for accessing Bluetooth baseband capabilities.
 In FreeBSD, a netgraph HCI node is created for each Bluetooth device.
 For more details, refer to man:ng_hci[4].
 
 One of the most common tasks is discovery of Bluetooth devices within RF proximity.
 This operation is called _inquiry_.
 Inquiry and other HCI related operations are done using man:hccontrol[8].
 The example below shows how to find out which Bluetooth devices are in range.
 The list of devices should be displayed in a few seconds.
 Note that a remote device will only answer the inquiry if it is set to _discoverable_ mode.
 
 [source,shell]
 ....
 % hccontrol -n ubt0hci inquiry
 Inquiry result, num_responses=1
 Inquiry result #0
        BD_ADDR: 00:80:37:29:19:a4
        Page Scan Rep. Mode: 0x1
        Page Scan Period Mode: 00
        Page Scan Mode: 00
        Class: 52:02:04
        Clock offset: 0x78ef
 Inquiry complete. Status: No error [00]
 ....
 
 The `BD_ADDR` is the unique address of a Bluetooth device, similar to the MAC address of a network card.
 This address is needed for further communication with a device and it is possible to assign a human readable name to a `BD_ADDR`.
 Information regarding the known Bluetooth hosts is contained in [.filename]#/etc/bluetooth/hosts#.
 The following example shows how to obtain the human readable name that was assigned to the remote device:
 
 [source,shell]
 ....
 % hccontrol -n ubt0hci remote_name_request 00:80:37:29:19:a4
 BD_ADDR: 00:80:37:29:19:a4
 Name: Pav's T39
 ....
 
 If an inquiry is performed on a remote Bluetooth device, it will find the computer as "your.host.name (ubt0)".
 The name assigned to the local device can be changed at any time.
 
 Remote devices can be assigned aliases in [.filename]#/etc/bluetooth/hosts#.
 More information about [.filename]#/etc/bluetooth/hosts# file might be found in man:bluetooth.hosts[5].
 
 The Bluetooth system provides a point-to-point connection between two Bluetooth units, or a point-to-multipoint connection which is shared among several Bluetooth devices.
 The following example shows how to create a connection to a remote device:
 
 [source,shell]
 ....
 % hccontrol -n ubt0hci create_connection BT_ADDR
 ....
 
 `create_connection` accepts `BT_ADDR` as well as host aliases in [.filename]#/etc/bluetooth/hosts#.
 
 The following example shows how to obtain the list of active baseband connections for the local device:
 
 [source,shell]
 ....
 % hccontrol -n ubt0hci read_connection_list
 Remote BD_ADDR    Handle Type Mode Role Encrypt Pending Queue State
 00:80:37:29:19:a4     41  ACL    0 MAST    NONE       0     0 OPEN
 ....
 
 A _connection handle_ is useful when termination of the baseband connection is required, though it is normally not required to do this by hand.
 The stack will automatically terminate inactive baseband connections.
 
 [source,shell]
 ....
 # hccontrol -n ubt0hci disconnect 41
 Connection handle: 41
 Reason: Connection terminated by local host [0x16]
 ....
 
 Type `hccontrol help` for a complete listing of available HCI commands.
 Most of the HCI commands do not require superuser privileges.
 
 === Device Pairing
 
 By default, Bluetooth communication is not authenticated, and any device can talk to any other device.
 A Bluetooth device, such as a cellular phone, may choose to require authentication to provide a particular service.
 Bluetooth authentication is normally done with a _PIN code_, an ASCII string up to 16 characters in length.
 The user is required to enter the same PIN code on both devices.
 Once the user has entered the PIN code, both devices will generate a _link key_.
 After that, the link key can be stored either in the devices or in a persistent storage.
 Next time, both devices will use the previously generated link key.
 This procedure is called _pairing_.
 Note that if the link key is lost by either device, the pairing must be repeated.
 
 The man:hcsecd[8] daemon is responsible for handling Bluetooth authentication requests.
 The default configuration file is [.filename]#/etc/bluetooth/hcsecd.conf#.
 An example section for a cellular phone with the PIN code set to `1234` is shown below:
 
 [.programlisting]
 ....
 device {
         bdaddr  00:80:37:29:19:a4;
         name    "Pav's T39";
         key     nokey;
         pin     "1234";
       }
 ....
 
 The only limitation on PIN codes is length.
 Some devices, such as Bluetooth headsets, may have a fixed PIN code built in.
 The `-d` switch forces man:hcsecd[8] to stay in the foreground, so it is easy to see what is happening.
 Set the remote device to receive pairing and initiate the Bluetooth connection to the remote device.
 The remote device should indicate that pairing was accepted and request the PIN code.
 Enter the same PIN code listed in [.filename]#hcsecd.conf#.
 Now the computer and the remote device are paired.
 Alternatively, pairing can be initiated on the remote device.
 
 The following line can be added to [.filename]#/etc/rc.conf# to configure man:hcsecd[8] to start automatically on system start:
 
 [.programlisting]
 ....
 hcsecd_enable="YES"
 ....
 
 The following is a sample of the man:hcsecd[8] daemon output:
 
 [.programlisting]
 ....
 hcsecd[16484]: Got Link_Key_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4
 hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', link key doesn't exist
 hcsecd[16484]: Sending Link_Key_Negative_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4
 hcsecd[16484]: Got PIN_Code_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4
 hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', PIN code exists
 hcsecd[16484]: Sending PIN_Code_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4
 ....
 
 === Network Access with PPP Profiles
 
 A Dial-Up Networking (DUN) profile can be used to configure a cellular phone as a wireless modem for connecting to a dial-up Internet access server.
 It can also be used to configure a computer to receive data calls from a cellular phone.
 
 Network access with a PPP profile can be used to provide LAN access for a single Bluetooth device or multiple Bluetooth devices.
 It can also provide PC to PC connection using PPP networking over serial cable emulation.
 
 In FreeBSD, these profiles are implemented with man:ppp[8] and the man:rfcomm_pppd[8] wrapper which converts a Bluetooth connection into something PPP can use.
 Before a profile can be used, a new PPP label must be created in [.filename]#/etc/ppp/ppp.conf#.
 Consult man:rfcomm_pppd[8] for examples.
 
 In this example, man:rfcomm_pppd[8] is used to open a connection to a remote device with a `BD_ADDR` of `00:80:37:29:19:a4` on a DUNRFCOMM channel:
 
 [source,shell]
 ....
 # rfcomm_pppd -a 00:80:37:29:19:a4 -c -C dun -l rfcomm-dialup
 ....
 
 The actual channel number will be obtained from the remote device using the SDP protocol.
 It is possible to specify the RFCOMM channel by hand, and in this case man:rfcomm_pppd[8] will not perform the SDP query.
 Use man:sdpcontrol[8] to find out the RFCOMM channel on the remote device.
 
 In order to provide network access with the PPPLAN service, man:sdpd[8] must be running and a new entry for LAN clients must be created in [.filename]#/etc/ppp/ppp.conf#.
 Consult man:rfcomm_pppd[8] for examples.
 Finally, start the RFCOMMPPP server on a valid RFCOMM channel number.
 The RFCOMMPPP server will automatically register the Bluetooth LAN service with the local SDP daemon.
 The example below shows how to start the RFCOMMPPP server.
 
 [source,shell]
 ....
 # rfcomm_pppd -s -C 7 -l rfcomm-server
 ....
 
 === Bluetooth Protocols
 
 This section provides an overview of the various Bluetooth protocols, their function, and associated utilities.
 
 ==== Logical Link Control and Adaptation Protocol (L2CAP)
 
 The Logical Link Control and Adaptation Protocol (L2CAP) provides connection-oriented and connectionless data services to upper layer protocols.
 L2CAP permits higher level protocols and applications to transmit and receive L2CAP data packets up to 64 kilobytes in length.
 
 L2CAP is based around the concept of _channels_.
 A channel is a logical connection on top of a baseband connection, where each channel is bound to a single protocol in a many-to-one fashion.
 Multiple channels can be bound to the same protocol, but a channel cannot be bound to multiple protocols.
 Each L2CAP packet received on a channel is directed to the appropriate higher level protocol.
 Multiple channels can share the same baseband connection.
 
 In FreeBSD, a netgraph L2CAP node is created for each Bluetooth device.
 This node is normally connected to the downstream Bluetooth HCI node and upstream Bluetooth socket nodes.
 The default name for the L2CAP node is "devicel2cap".
 For more details refer to man:ng_l2cap[4].
 
 A useful command is man:l2ping[8], which can be used to ping other devices. 
 Some Bluetooth implementations might not return all of the data sent to them, so `0 bytes` in the following example is normal.
 
 [source,shell]
 ....
 # l2ping -a 00:80:37:29:19:a4
 0 bytes from 0:80:37:29:19:a4 seq_no=0 time=48.633 ms result=0
 0 bytes from 0:80:37:29:19:a4 seq_no=1 time=37.551 ms result=0
 0 bytes from 0:80:37:29:19:a4 seq_no=2 time=28.324 ms result=0
 0 bytes from 0:80:37:29:19:a4 seq_no=3 time=46.150 ms result=0
 ....
 
 The man:l2control[8] utility is used to perform various operations on L2CAP nodes.
 This example shows how to obtain the list of logical connections (channels) and the list of baseband connections for the local device:
 
 [source,shell]
 ....
 % l2control -a 00:02:72:00:d4:1a read_channel_list
 L2CAP channels:
 Remote BD_ADDR     SCID/ DCID   PSM  IMTU/ OMTU State
 00:07:e0:00:0b:ca    66/   64     3   132/  672 OPEN
 % l2control -a 00:02:72:00:d4:1a read_connection_list
 L2CAP connections:
 Remote BD_ADDR    Handle Flags Pending State
 00:07:e0:00:0b:ca     41 O           0 OPEN
 ....
 
 Another diagnostic tool is man:btsockstat[1].
 It is similar to man:netstat[1], but for Bluetooth network-related data structures.
 The example below shows the same logical connection as man:l2control[8] above.
 
 [source,shell]
 ....
 % btsockstat
 Active L2CAP sockets
 PCB      Recv-Q Send-Q Local address/PSM       Foreign address   CID   State
 c2afe900      0      0 00:02:72:00:d4:1a/3     00:07:e0:00:0b:ca 66    OPEN
 Active RFCOMM sessions
 L2PCB    PCB      Flag MTU   Out-Q DLCs State
 c2afe900 c2b53380 1    127   0     Yes  OPEN
 Active RFCOMM sockets
 PCB      Recv-Q Send-Q Local address     Foreign address   Chan DLCI State
 c2e8bc80      0    250 00:02:72:00:d4:1a 00:07:e0:00:0b:ca 3    6    OPEN
 ....
 
 ==== Radio Frequency Communication (RFCOMM)
 
 The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol.
 RFCOMM is a simple transport protocol, with additional provisions for emulating the 9 circuits of RS-232 (EIATIA-232-E) serial ports.
 It supports up to 60 simultaneous connections (RFCOMM channels) between two Bluetooth devices.
 
 For the purposes of RFCOMM, a complete communication path involves two applications running on the communication endpoints with a communication segment between them.
 RFCOMM is intended to cover applications that make use of the serial ports of the devices in which they reside.
 The communication segment is a direct connect Bluetooth link from one device to another.
 
 RFCOMM is only concerned with the connection between the devices in the direct connect case, or between the device and a modem in the network case. 
 RFCOMM can support other configurations, such as modules that communicate via Bluetooth wireless technology on one side and provide a wired interface on the other side.
 
 In FreeBSD, RFCOMM is implemented at the Bluetooth sockets layer.
 
 ==== Service Discovery Protocol (SDP)
 
 The Service Discovery Protocol (SDP) provides the means for client applications to discover the existence of services provided by server applications as well as the attributes of those services.
 The attributes of a service include the type or class of service offered and the mechanism or protocol information needed to utilize the service.
 
 SDP involves communication between a SDP server and a SDP client.
 The server maintains a list of service records that describe the characteristics of services associated with the server.
 Each service record contains information about a single service.
 A client may retrieve information from a service record maintained by the SDP server by issuing a SDP request.
 If the client, or an application associated with the client, decides to use a service, it must open a separate connection to the service provider in order to utilize the service.
 SDP provides a mechanism for discovering services and their attributes, but it does not provide a mechanism for utilizing those services.
 
 Normally, a SDP client searches for services based on some desired characteristics of the services.
 However, there are times when it is desirable to discover which types of services are described by an SDP server's service records without any prior information about the services.
 This process of looking for any offered services is called _browsing_.
 
 The Bluetooth SDP server, man:sdpd[8], and command line client, man:sdpcontrol[8], are included in the standard FreeBSD installation.
 The following example shows how to perform a SDP browse query.
 
 [source,shell]
 ....
 % sdpcontrol -a 00:01:03:fc:6e:ec browse
 Record Handle: 00000000
 Service Class ID List:
         Service Discovery Server (0x1000)
 Protocol Descriptor List:
         L2CAP (0x0100)
                 Protocol specific parameter #1: u/int/uuid16 1
                 Protocol specific parameter #2: u/int/uuid16 1
 
 Record Handle: 0x00000001
 Service Class ID List:
         Browse Group Descriptor (0x1001)
 
 Record Handle: 0x00000002
 Service Class ID List:
         LAN Access Using PPP (0x1102)
 Protocol Descriptor List:
         L2CAP (0x0100)
         RFCOMM (0x0003)
                 Protocol specific parameter #1: u/int8/bool 1
 Bluetooth Profile Descriptor List:
         LAN Access Using PPP (0x1102) ver. 1.0
 ....
 
 Note that each service has a list of attributes, such as the RFCOMM channel.
 Depending on the service, the user might need to make note of some of the attributes.
 Some Bluetooth implementations do not support service browsing and may return an empty list.
 In this case, it is possible to search for the specific service.
 The example below shows how to search for the OBEX Object Push (OPUSH) service:
 
 [source,shell]
 ....
 % sdpcontrol -a 00:01:03:fc:6e:ec search OPUSH
 ....
 
 Offering services on FreeBSD to Bluetooth clients is done with the man:sdpd[8] server.
 The following line can be added to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 sdpd_enable="YES"
 ....
 
 Then the man:sdpd[8] daemon can be started with:
 
 [source,shell]
 ....
 # service sdpd start
 ....
 
 The local server application that wants to provide a Bluetooth service to remote clients will register the service with the local SDP daemon.
 An example of such an application is man:rfcomm_pppd[8].
 Once started, it will register the Bluetooth LAN service with the local SDP daemon.
 
 The list of services registered with the local SDP server can be obtained by issuing a SDP browse query via the local control channel:
 
 [source,shell]
 ....
 # sdpcontrol -l browse
 ....
 
 ==== OBEX Object Push (OPUSH)
 
 Object Exchange (OBEX) is a widely used protocol for simple file transfers between mobile devices.
 Its main use is in infrared communication, where it is used for generic file transfers between notebooks or PDAs, and for sending business cards or calendar entries between cellular phones and other devices with Personal Information Manager (PIM) applications.
 
 The OBEX server and client are implemented by obexapp, which can be installed using the package:comms/obexapp[] package or port.
 
 The OBEX client is used to push and/or pull objects from the OBEX server.
 An example object is a business card or an appointment.
 The OBEX client can obtain the RFCOMM channel number from the remote device via SDP.
 This can be done by specifying the service name instead of the RFCOMM channel number.
 Supported service names are: `IrMC`, `FTRN`, and `OPUSH`.
 It is also possible to specify the RFCOMM channel as a number.
 Below is an example of an OBEX session where the device information object is pulled from the cellular phone, and a new object, the business card, is pushed into the phone's directory.
 
 [source,shell]
 ....
 % obexapp -a 00:80:37:29:19:a4 -C IrMC
 obex> get telecom/devinfo.txt devinfo-t39.txt
 Success, response: OK, Success (0x20)
 obex> put new.vcf
 Success, response: OK, Success (0x20)
 obex> di
 Success, response: OK, Success (0x20)
 ....
 
 In order to provide the OPUSH service, man:sdpd[8] must be running and a root folder, where all incoming objects will be stored, must be created.
 The default path to the root folder is [.filename]#/var/spool/obex#.
 Finally, start the OBEX server on a valid RFCOMM channel number.
 The OBEX server will automatically register the OPUSH service with the local SDP daemon.
 The example below shows how to start the OBEX server.
 
 [source,shell]
 ....
 # obexapp -s -C 10
 ....
 
 ==== Serial Port Profile (SPP)
 
 The Serial Port Profile (SPP) allows Bluetooth devices to perform serial cable emulation.
 This profile allows legacy applications to use Bluetooth as a cable replacement, through a virtual serial port abstraction.
 
 In FreeBSD, man:rfcomm_sppd[1] implements SPP and a pseudo tty is used as a virtual serial port abstraction.
 The example below shows how to connect to a remote device's serial port service.
 A RFCOMM channel does not have to be specified as man:rfcomm_sppd[1] can obtain it from the remote device via SDP.
 To override this, specify a RFCOMM channel on the command line.
 
 [source,shell]
 ....
 # rfcomm_sppd -a 00:07:E0:00:0B:CA -t
 rfcomm_sppd[94692]: Starting on /dev/pts/6...
 /dev/pts/6
 ....
 
 Once connected, the pseudo tty can be used as serial port:
 
 [source,shell]
 ....
 # cu -l /dev/pts/6
 ....
 
 The pseudo tty is printed on stdout and can be read by wrapper scripts:
 
 [.programlisting]
 ....
 PTS=`rfcomm_sppd -a 00:07:E0:00:0B:CA -t`
 cu -l $PTS
 ....
 
 === Troubleshooting
 
 By default, when FreeBSD is accepting a new connection, it tries to perform a role switch and become master.
 Some older Bluetooth devices which do not support role switching will not be able to connect.
 Since role switching is performed when a new connection is being established, it is not possible to ask the remote device if it supports role switching. 
 However, there is a HCI option to disable role switching on the local side:
 
 [source,shell]
 ....
 # hccontrol -n ubt0hci write_node_role_switch 0
 ....
 
 To display Bluetooth packets, use the third-party package hcidump, which can be installed using the package:comms/hcidump[] package or port.
 This utility is similar to man:tcpdump[1] and can be used to display the contents of Bluetooth packets on the terminal and to dump the Bluetooth packets to a file.
 
 [[network-bridging]]
 == Bridging
 
 It is sometimes useful to divide a network, such as an Ethernet segment, into network segments without having to create IP subnets and use a router to connect the segments together.
 A device that connects two networks together in this fashion is called a "bridge".
 
 A bridge works by learning the MAC addresses of the devices on each of its network interfaces.
 It forwards traffic between networks only when the source and destination MAC addresses are on different networks.
 In many respects, a bridge is like an Ethernet switch with very few ports.
 A FreeBSD system with multiple network interfaces can be configured to act as a bridge.
 
 Bridging can be useful in the following situations:
 
 Connecting Networks::
 The basic operation of a bridge is to join two or more network segments.
 There are many reasons to use a host-based bridge instead of networking equipment, such as cabling constraints or firewalling.
 A bridge can also connect a wireless interface running in hostap mode to a wired network and act as an access point.
 
 Filtering/Traffic Shaping Firewall::
 A bridge can be used when firewall functionality is needed without routing or Network Address Translation (NAT).
 +
 An example is a small company that is connected via DSL or ISDN to an ISP.
 There are thirteen public IP addresses from the ISP and ten computers on the network.
 In this situation, using a router-based firewall is difficult because of subnetting issues.
 A bridge-based firewall can be configured without any IP addressing issues.
 
 Network Tap::
 A bridge can join two network segments in order to inspect all Ethernet frames that pass between them using man:bpf[4] and man:tcpdump[1] on the bridge interface or by sending a copy of all frames out an additional interface known as a span port.
 
 Layer 2 VPN::
 Two Ethernet networks can be joined across an IP link by bridging the networks to an EtherIP tunnel or a man:tap[4] based solution such as OpenVPN.
 
 Layer 2 Redundancy::
 A network can be connected together with multiple links and use the Spanning Tree Protocol (STP) to block redundant paths.
 
 This section describes how to configure a FreeBSD system as a bridge using man:if_bridge[4].
 A netgraph bridging driver is also available, and is described in man:ng_bridge[4].
 
 [NOTE]
 ====
 Packet filtering can be used with any firewall package that hooks into the man:pfil[9] framework.
 The bridge can be used as a traffic shaper with man:altq[4] or man:dummynet[4].
 ====
 
 === Enabling the Bridge
 
 In FreeBSD, man:if_bridge[4] is a kernel module which is automatically loaded by man:ifconfig[8] when creating a bridge interface.
 It is also possible to compile bridge support into a custom kernel by adding `device if_bridge` to the custom kernel configuration file.
 
 The bridge is created using interface cloning.
 To create the bridge interface:
 
 [source,shell]
 ....
 # ifconfig bridge create
 bridge0
 # ifconfig bridge0
 bridge0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
         ether 96:3d:4b:f1:79:7a
         id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
         maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
         root id 00:00:00:00:00:00 priority 0 ifcost 0 port 0
 ....
 
 When a bridge interface is created, it is automatically assigned a randomly generated Ethernet address.
 The `maxaddr` and `timeout` parameters control how many MAC addresses the bridge will keep in its forwarding table and how many seconds before each entry is removed after it is last seen.
 The other parameters control how STP operates.
 
 Next, specify which network interfaces to add as members of the bridge.
 For the bridge to forward packets, all member interfaces and the bridge need to be up:
 
 [source,shell]
 ....
 # ifconfig bridge0 addm fxp0 addm fxp1 up
 # ifconfig fxp0 up
 # ifconfig fxp1 up
 ....
 
 The bridge can now forward Ethernet frames between [.filename]#fxp0# and [.filename]#fxp1#.
 Add the following lines to [.filename]#/etc/rc.conf# so the bridge is created at startup:
 
 [.programlisting]
 ....
 cloned_interfaces="bridge0"
 ifconfig_bridge0="addm fxp0 addm fxp1 up"
 ifconfig_fxp0="up"
 ifconfig_fxp1="up"
 ....
 
 If the bridge host needs an IP address, set it on the bridge interface, not on the member interfaces.
 The address can be set statically or via DHCP.
 This example sets a static IP address:
 
 [source,shell]
 ....
 # ifconfig bridge0 inet 192.168.0.1/24
 ....
 
 It is also possible to assign an IPv6 address to a bridge interface.
 To make the changes permanent, add the addressing information to [.filename]#/etc/rc.conf#.
 
 [NOTE]
 ====
 When packet filtering is enabled, bridged packets will pass through the filter inbound on the originating interface on the bridge interface, and outbound on the appropriate interfaces.
 Either stage can be disabled.
 When direction of the packet flow is important, it is best to firewall on the member interfaces rather than the bridge itself.
 
 The bridge has several configurable settings for passing non-IP and IP packets, and layer2 firewalling with man:ipfw[8].
 See man:if_bridge[4] for more information.
 ====
 
 === Enabling Spanning Tree
 
 For an Ethernet network to function properly, only one active path can exist between two devices.
 The STP protocol detects loops and puts redundant links into a blocked state.
 Should one of the active links fail, STP calculates a different tree and enables one of the blocked paths to restore connectivity to all points in the network.
 
 The Rapid Spanning Tree Protocol (RSTP or 802.1w) provides backwards compatibility with legacy STP.
 RSTP provides faster convergence and exchanges information with neighboring switches to quickly transition to forwarding mode without creating loops. 
 FreeBSD supports RSTP and STP as operating modes, with RSTP being the default mode.
 
 STP can be enabled on member interfaces using man:ifconfig[8].
 For a bridge with [.filename]#fxp0# and [.filename]#fxp1# as the current interfaces, enable STP with:
 
 [source,shell]
 ....
 # ifconfig bridge0 stp fxp0 stp fxp1
 bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
         ether d6:cf:d5:a0:94:6d
         id 00:01:02:4b:d4:50 priority 32768 hellotime 2 fwddelay 15
         maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
         root id 00:01:02:4b:d4:50 priority 32768 ifcost 0 port 0
         member: fxp0 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
                 port 3 priority 128 path cost 200000 proto rstp
                 role designated state forwarding
         member: fxp1 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
                 port 4 priority 128 path cost 200000 proto rstp
                 role designated state forwarding
 ....
 
 This bridge has a spanning tree ID of `00:01:02:4b:d4:50` and a priority of `32768`.
 As the `root id` is the same, it indicates that this is the root bridge for the tree.
 
 Another bridge on the network also has STP enabled:
 
 [source,shell]
 ....
 bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
         ether 96:3d:4b:f1:79:7a
         id 00:13:d4:9a:06:7a priority 32768 hellotime 2 fwddelay 15
         maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
         root id 00:01:02:4b:d4:50 priority 32768 ifcost 400000 port 4
         member: fxp0 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
                 port 4 priority 128 path cost 200000 proto rstp
                 role root state forwarding
         member: fxp1 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
                 port 5 priority 128 path cost 200000 proto rstp
                 role designated state forwarding
 ....
 
 The line `root id 00:01:02:4b:d4:50 priority 32768 ifcost 400000 port 4` shows that the root bridge is `00:01:02:4b:d4:50` and has a path cost of `400000` from this bridge.
 The path to the root bridge is via `port 4` which is [.filename]#fxp0#.
 
 === Bridge Interface Parameters
 
 Several `ifconfig` parameters are unique to bridge interfaces.
 This section summarizes some common uses for these parameters.
 The complete list of available parameters is described in man:ifconfig[8].
 
 private::
 A private interface does not forward any traffic to any other port that is also designated as a private interface.
 The traffic is blocked unconditionally so no Ethernet frames will be forwarded, including ARP packets.
 If traffic needs to be selectively blocked, a firewall should be used instead.
 
 span::
 A span port transmits a copy of every Ethernet frame received by the bridge.
 The number of span ports configured on a bridge is unlimited, but if an interface is designated as a span port, it cannot also be used as a regular bridge port.
 This is most useful for snooping a bridged network passively on another host connected to one of the span ports of the bridge.
 For example, to send a copy of all frames out the interface named [.filename]#fxp4#:
 +
 [source,shell]
 ....
 # ifconfig bridge0 span fxp4
 ....
 
 sticky::
 If a bridge member interface is marked as sticky, dynamically learned address entries are treated as static entries in the forwarding cache.
 Sticky entries are never aged out of the cache or replaced, even if the address is seen on a different interface.
 This gives the benefit of static address entries without the need to pre-populate the forwarding table.
 Clients learned on a particular segment of the bridge cannot roam to another segment.
 +
 An example of using sticky addresses is to combine the bridge with VLANs in order to isolate customer networks without wasting IP address space. 
 Consider that `CustomerA` is on `vlan100`, `CustomerB` is on `vlan101`, and the bridge has the address `192.168.0.1`:
 +
 [source,shell]
 ....
 # ifconfig bridge0 addm vlan100 sticky vlan100 addm vlan101 sticky vlan101
 # ifconfig bridge0 inet 192.168.0.1/24
 ....
 +
 In this example, both clients see `192.168.0.1` as their default gateway.
 Since the bridge cache is sticky, one host cannot spoof the MAC address of the other customer in order to intercept their traffic.
 +
 Any communication between the VLANs can be blocked using a firewall or, as seen in this example, private interfaces:
 +
 [source,shell]
 ....
 # ifconfig bridge0 private vlan100 private vlan101
 ....
 +
 The customers are completely isolated from each other and the full `/24` address range can be allocated without subnetting.
 +
 The number of unique source MAC addresses behind an interface can be limited.
 Once the limit is reached, packets with unknown source addresses are dropped until an existing host cache entry expires or is removed.
 +
 The following example sets the maximum number of Ethernet devices for `CustomerA` on `vlan100` to 10:
 +
 [source,shell]
 ....
 # ifconfig bridge0 ifmaxaddr vlan100 10
 ....
 
 Bridge interfaces also support monitor mode, where the packets are discarded after man:bpf[4] processing and are not processed or forwarded further. 
 This can be used to multiplex the input of two or more interfaces into a single man:bpf[4] stream.
 This is useful for reconstructing the traffic for network taps that transmit the RX/TX signals out through two separate interfaces.
 For example, to read the input from four network interfaces as one stream:
 
 [source,shell]
 ....
 # ifconfig bridge0 addm fxp0 addm fxp1 addm fxp2 addm fxp3 monitor up
 # tcpdump -i bridge0
 ....
 
 === SNMP Monitoring
 
 The bridge interface and STP parameters can be monitored via man:bsnmpd[1] which is included in the FreeBSD base system.
 The exported bridge MIBs conform to IETF standards so any SNMP client or monitoring package can be used to retrieve the data.
 
 To enable monitoring on the bridge, uncomment this line in [.filename]#/etc/snmpd.config# by removing the beginning `#` symbol:
 
 [.programlisting]
 ....
 begemotSnmpdModulePath."bridge" = "/usr/lib/snmp_bridge.so"
 ....
 
 Other configuration settings, such as community names and access lists, may need to be modified in this file.
 See man:bsnmpd[1] and man:snmp_bridge[3] for more information.
 Once these edits are saved, add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 bsnmpd_enable="YES"
 ....
 
 Then, start man:bsnmpd[1]:
 
 [source,shell]
 ....
 # service bsnmpd start
 ....
 
 The following examples use the Net-SNMP software (package:net-mgmt/net-snmp[]) to query a bridge from a client system.
 The package:net-mgmt/bsnmptools[] port can also be used.
 From the SNMP client which is running Net-SNMP, add the following lines to [.filename]#$HOME/.snmp/snmp.conf# in order to import the bridge MIB definitions:
 
 [.programlisting]
 ....
 mibdirs +/usr/share/snmp/mibs
 mibs +BRIDGE-MIB:RSTP-MIB:BEGEMOT-MIB:BEGEMOT-BRIDGE-MIB
 ....
 
 To monitor a single bridge using the IETF BRIDGE-MIB (RFC4188):
 
 [source,shell]
 ....
 % snmpwalk -v 2c -c public bridge1.example.com mib-2.dot1dBridge
 BRIDGE-MIB::dot1dBaseBridgeAddress.0 = STRING: 66:fb:9b:6e:5c:44
 BRIDGE-MIB::dot1dBaseNumPorts.0 = INTEGER: 1 ports
 BRIDGE-MIB::dot1dStpTimeSinceTopologyChange.0 = Timeticks: (189959) 0:31:39.59 centi-seconds
 BRIDGE-MIB::dot1dStpTopChanges.0 = Counter32: 2
 BRIDGE-MIB::dot1dStpDesignatedRoot.0 = Hex-STRING: 80 00 00 01 02 4B D4 50
 ...
 BRIDGE-MIB::dot1dStpPortState.3 = INTEGER: forwarding(5)
 BRIDGE-MIB::dot1dStpPortEnable.3 = INTEGER: enabled(1)
 BRIDGE-MIB::dot1dStpPortPathCost.3 = INTEGER: 200000
 BRIDGE-MIB::dot1dStpPortDesignatedRoot.3 = Hex-STRING: 80 00 00 01 02 4B D4 50
 BRIDGE-MIB::dot1dStpPortDesignatedCost.3 = INTEGER: 0
 BRIDGE-MIB::dot1dStpPortDesignatedBridge.3 = Hex-STRING: 80 00 00 01 02 4B D4 50
 BRIDGE-MIB::dot1dStpPortDesignatedPort.3 = Hex-STRING: 03 80
 BRIDGE-MIB::dot1dStpPortForwardTransitions.3 = Counter32: 1
 RSTP-MIB::dot1dStpVersion.0 = INTEGER: rstp(2)
 ....
 
 The `dot1dStpTopChanges.0` value is two, indicating that the STP bridge topology has changed twice.
 A topology change means that one or more links in the network have changed or failed and a new tree has been calculated.
 The `dot1dStpTimeSinceTopologyChange.0` value will show when this happened.
 
 To monitor multiple bridge interfaces, the private BEGEMOT-BRIDGE-MIB can be used:
 
 [source,shell]
 ....
 % snmpwalk -v 2c -c public bridge1.example.com
 enterprises.fokus.begemot.begemotBridge
 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge0" = STRING: bridge0
 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge2" = STRING: bridge2
 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseAddress."bridge0" = STRING: e:ce:3b:5a:9e:13
 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseAddress."bridge2" = STRING: 12:5e:4d:74:d:fc
 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseNumPorts."bridge0" = INTEGER: 1
 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseNumPorts."bridge2" = INTEGER: 1
 ...
 BEGEMOT-BRIDGE-MIB::begemotBridgeStpTimeSinceTopologyChange."bridge0" = Timeticks: (116927) 0:19:29.27 centi-seconds
 BEGEMOT-BRIDGE-MIB::begemotBridgeStpTimeSinceTopologyChange."bridge2" = Timeticks: (82773) 0:13:47.73 centi-seconds
 BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge0" = Counter32: 1
 BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge2" = Counter32: 1
 BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge0" = Hex-STRING: 80 00 00 40 95 30 5E 31
 BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge2" = Hex-STRING: 80 00 00 50 8B B8 C6 A9
 ....
 
 To change the bridge interface being monitored via the `mib-2.dot1dBridge` subtree:
 
 [source,shell]
 ....
 % snmpset -v 2c -c private bridge1.example.com
 BEGEMOT-BRIDGE-MIB::begemotBridgeDefaultBridgeIf.0 s bridge2
 ....
 
 [[network-aggregation]]
 == Link Aggregation and Failover
 
 FreeBSD provides the man:lagg[4] interface which can be used to aggregate multiple network interfaces into one virtual interface in order to provide failover and link aggregation.
 Failover allows traffic to continue to flow as long as at least one aggregated network interface has an established link.
 Link aggregation works best on switches which support LACP, as this protocol distributes traffic bi-directionally while responding to the failure of individual links.
 
 The aggregation protocols supported by the lagg interface determine which ports are used for outgoing traffic and whether or not a specific port accepts incoming traffic.
 The following protocols are supported by man:lagg[4]:
 
 failover::
 This mode sends and receives traffic only through the master port.
 If the master port becomes unavailable, the next active port is used.
 The first interface added to the virtual interface is the master port and all subsequently added interfaces are used as failover devices.
 If failover to a non-master port occurs, the original port becomes master once it becomes available again.
 
 fec / loadbalance::
 Cisco(R) Fast EtherChannel(R) (FEC) is found on older Cisco(R) switches.
 It provides a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link.
 If the switch supports LACP, that should be used instead.
 
 lacp::
 The IEEE(R) 802.3ad Link Aggregation Control Protocol (LACP) negotiates a set of aggregable links with the peer into one or more Link Aggregated Groups (LAGs).
 Each LAG is composed of ports of the same speed, set to full-duplex operation, and traffic is balanced across the ports in the LAG with the greatest total speed.
 Typically, there is only one LAG which contains all the ports.
 In the event of changes in physical connectivity, LACP will quickly converge to a new configuration.
 +
 LACP balances outgoing traffic across the active ports based on hashed protocol header information and accepts incoming traffic from any active port. 
 The hash includes the Ethernet source and destination address and, if available, the VLAN tag, and the IPv4 or IPv6 source and destination address.
 
 roundrobin::
 This mode distributes outgoing traffic using a round-robin scheduler through all active ports and accepts incoming traffic from any active port.
 Since this mode violates Ethernet frame ordering, it should be used with caution.
 
 === Configuration Examples
 
 This section demonstrates how to configure a Cisco(R) switch and a FreeBSD system for LACP load balancing.
 It then shows how to configure two Ethernet interfaces in failover mode as well as how to configure failover mode between an Ethernet and a wireless interface.
 
 [[networking-lacp-aggregation-cisco]]
 .LACP Aggregation with a Cisco(R) Switch
 [example]
 ====
 This example connects two man:fxp[4] Ethernet interfaces on a FreeBSD machine to the first two Ethernet ports on a Cisco(R) switch as a single load balanced and fault tolerant link.
 More interfaces can be added to increase throughput and fault tolerance.
 Replace the names of the Cisco(R) ports, Ethernet devices, channel group number, and IP address shown in the example to match the local configuration.
 
 Frame ordering is mandatory on Ethernet links and any traffic between two stations always flows over the same physical link, limiting the maximum speed to that of one interface.
 The transmit algorithm attempts to use as much information as it can to distinguish different traffic flows and balance the flows across the available interfaces.
 
 On the Cisco(R) switch, add the _FastEthernet0/1_ and _FastEthernet0/2_ interfaces to channel group _1_:
 
 [source,shell]
 ....
 interface FastEthernet0/1
  channel-group 1 mode active
  channel-protocol lacp
 !
 interface FastEthernet0/2
  channel-group 1 mode active
  channel-protocol lacp
 ....
 
 On the FreeBSD system, create the man:lagg[4] interface using the physical interfaces _fxp0_ and _fxp1_ and bring the interfaces up with an IP address of _10.0.0.3/24_:
 
 [source,shell]
 ....
 # ifconfig fxp0 up
 # ifconfig fxp1 up
 # ifconfig lagg0 create
 # ifconfig lagg0 up laggproto lacp laggport fxp0 laggport fxp1 10.0.0.3/24
 ....
 
 Next, verify the status of the virtual interface:
 
 [source,shell]
 ....
 # ifconfig lagg0
 lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
         options=8<VLAN_MTU>
         ether 00:05:5d:71:8d:b8
         inet 10.0.0.3 netmask 0xffffff00 broadcast 10.0.0.255
         media: Ethernet autoselect
         status: active
         laggproto lacp
         laggport: fxp1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
         laggport: fxp0 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
 ....
 
 Ports marked as `ACTIVE` are part of the LAG that has been negotiated with the remote switch.
 Traffic will be transmitted and received through these active ports.
 Add `-v` to the above command to view the LAG identifiers.
 
 To see the port status on the Cisco(R) switch:
 
 [source,shell]
 ....
 switch# show lacp neighbor
 Flags:  S - Device is requesting Slow LACPDUs
         F - Device is requesting Fast LACPDUs
         A - Device is in Active mode       P - Device is in Passive mode
 
 Channel group 1 neighbors
 
 Partner's information:
 
                   LACP port                        Oper    Port     Port
 Port      Flags   Priority  Dev ID         Age     Key     Number   State
 Fa0/1     SA      32768     0005.5d71.8db8  29s    0x146   0x3      0x3D
 Fa0/2     SA      32768     0005.5d71.8db8  29s    0x146   0x4      0x3D
 ....
 
 For more detail, type `show lacp neighbor detail`.
 
 To retain this configuration across reboots, add the following entries to [.filename]#/etc/rc.conf# on the FreeBSD system:
 
 [.programlisting]
 ....
 ifconfig_fxp0="up"
 ifconfig_fxp1="up"
 cloned_interfaces="lagg0"
 ifconfig_lagg0="laggproto lacp laggport fxp0 laggport fxp1 10.0.0.3/24"
 ....
 
 ====
 
 [[networking-lagg-failover]]
 .Failover Mode
 [example]
 ====
 
 Failover mode can be used to switch over to a secondary interface if the link is lost on the master interface.
 To configure failover, make sure that the underlying physical interfaces are up, then create the man:lagg[4] interface.
 In this example, _fxp0_ is the master interface, _fxp1_ is the secondary interface, and the virtual interface is assigned an IP address of _10.0.0.15/24_:
 
 [source,shell]
 ....
 # ifconfig fxp0 up
 # ifconfig fxp1 up
 # ifconfig lagg0 create
 # ifconfig lagg0 up laggproto failover laggport fxp0 laggport fxp1 10.0.0.15/24
 ....
 
 The virtual interface should look something like this:
 
 [source,shell]
 ....
 # ifconfig lagg0
 lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
         options=8<VLAN_MTU>
         ether 00:05:5d:71:8d:b8
         inet 10.0.0.15 netmask 0xffffff00 broadcast 10.0.0.255
         media: Ethernet autoselect
         status: active
         laggproto failover
         laggport: fxp1 flags=0<>
         laggport: fxp0 flags=5<MASTER,ACTIVE>
 ....
 
 Traffic will be transmitted and received on _fxp0_.
 If the link is lost on _fxp0_, _fxp1_ will become the active link.
 If the link is restored on the master interface, it will once again become the active link.
 
 To retain this configuration across reboots, add the following entries to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 ifconfig_fxp0="up"
 ifconfig_fxp1="up"
 cloned_interfaces="lagg0"
 ifconfig_lagg0="laggproto failover laggport fxp0 laggport fxp1 10.0.0.15/24"
 ....
 
 ====
 
 [[networking-lagg-wired-and-wireless]]
 .Failover Mode Between Ethernet and Wireless Interfaces
 [example]
 ====
 
 For laptop users, it is usually desirable to configure the wireless device as a secondary which is only used when the Ethernet connection is not available. 
 With man:lagg[4], it is possible to configure a failover which prefers the Ethernet connection for both performance and security reasons, while maintaining the ability to transfer data over the wireless connection.
 
 This is achieved by overriding the Ethernet interface's MAC address with that of the wireless interface.
 
 [NOTE]
 ****
 In theory, either the Ethernet or wireless MAC address can be changed to match the other.
 However, some popular wireless interfaces lack support for overriding the MAC address.
 We therefore recommend overriding the Ethernet MAC address for this purpose.
 ****
 
 [NOTE]
 ****
 If the driver for the wireless interface is not loaded in the `GENERIC` or custom kernel, and the computer is running FreeBSD {rel121-current}, load the corresponding [.filename]#.ko# in [.filename]#/boot/loader.conf# by adding `*driver_load="YES"*` to that file and rebooting.
 Another, better way is to load the driver in [.filename]#/etc/rc.conf# by adding it to `kld_list` (see man:rc.conf[5] for details) in that file and rebooting. 
 This is needed because otherwise the driver is not loaded yet at the time the man:lagg[4] interface is set up.
 ****
 
 In this example, the Ethernet interface, _re0_, is the master and the wireless interface, _wlan0_, is the failover.
 The _wlan0_ interface was created from the _ath0_ physical wireless interface, and the Ethernet interface will be configured with the MAC address of the wireless interface.
 First, determine the MAC address of the wireless interface:
 
 [source,shell]
 ....
 # ifconfig wlan0
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 	ether b8:ee:65:5b:32:59
 	groups: wlan
 	ssid Bbox-A3BD2403 channel 6 (2437 MHz 11g ht/20) bssid 00:37:b7:56:4b:60
 	regdomain ETSI country FR indoor ecm authmode WPA2/802.11i privacy ON
 	deftxkey UNDEF AES-CCM 2:128-bit txpower 30 bmiss 7 scanvalid 60
 	protmode CTS ampdulimit 64k ampdudensity 8 shortgi -stbctx stbcrx
 	-ldpc wme burst roaming MANUAL
 	media: IEEE 802.11 Wireless Ethernet MCS mode 11ng
 	status: associated
 	nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
 ....
 
 Replace _wlan0_ to match the system's wireless interface name.
 The `ether` line will contain the MAC address of the specified interface.
 Now, change the MAC address of the Ethernet interface:
 
 [source,shell]
 ....
 # ifconfig re0 ether b8:ee:65:5b:32:59
 ....
 
 Bring the wireless interface up (replacing _FR_ with your own 2-letter country code), but do not set an IP address:
 
 [source,shell]
 ....
 # ifconfig wlan0 create wlandev ath0 country FR ssid my_router up
 ....
 
 Make sure the _re0_ interface is up, then create the man:lagg[4] interface with _re0_ as master with failover to _wlan0_:
 
 [source,shell]
 ....
 # ifconfig re0 up
 # ifconfig lagg0 create
 # ifconfig lagg0 up laggproto failover laggport re0 laggport wlan0
 ....
 
 The virtual interface should look something like this:
 
 [source,shell]
 ....
 # ifconfig lagg0
 lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
         options=8<VLAN_MTU>
         ether b8:ee:65:5b:32:59
         laggproto failover lagghash l2,l3,l4
         laggport: re0 flags=5<MASTER,ACTIVE>
         laggport: wlan0 flags=0<>
         groups: lagg
         media: Ethernet autoselect
         status: active
 ....
 
 Then, start the DHCP client to obtain an IP address:
 
 [source,shell]
 ....
 # dhclient lagg0
 ....
 
 To retain this configuration across reboots, add the following entries to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 ifconfig_re0="ether b8:ee:65:5b:32:59"
 wlans_ath0="wlan0"
 ifconfig_wlan0="WPA"
 create_args_wlan0="country FR"
 cloned_interfaces="lagg0"
 ifconfig_lagg0="up laggproto failover laggport re0 laggport wlan0 DHCP"
 ....
 
 ====
 
 [[network-diskless]]
 == Diskless Operation with PXE
 
 The Intel(R) Preboot eXecution Environment (PXE) allows an operating system to boot over the network.
 For example, a FreeBSD system can boot over the network and operate without a local disk, using file systems mounted from an NFS server.
 PXE support is usually available in the BIOS.
 To use PXE when the machine starts, select the `Boot from network` option in the BIOS setup or type a function key during system initialization.
 
 In order to provide the files needed for an operating system to boot over the network, a PXE setup also requires properly configured DHCP, TFTP, and NFS servers, where:
 
 * Initial parameters, such as an IP address, executable boot filename and location, server name, and root path are obtained from the DHCP server.
 * The operating system loader file is booted using TFTP.
 * The file systems are loaded using NFS.
 
 When a computer PXE boots, it receives information over DHCP about where to obtain the initial boot loader file.
 After the host computer receives this information, it downloads the boot loader via TFTP and then executes the boot loader.
 In FreeBSD, the boot loader file is [.filename]#/boot/pxeboot#.
 After [.filename]#/boot/pxeboot# executes, the FreeBSD kernel is loaded and the rest of the FreeBSD bootup sequence proceeds, as described in crossref:boot[boot,The FreeBSD Booting Process].
 
 This section describes how to configure these services on a FreeBSD system so that other systems can PXE boot into FreeBSD.
 Refer to man:diskless[8] for more information.
 
 [CAUTION]
 ====
 As described, the system providing these services is insecure.
 It should live in a protected area of a network and be untrusted by other hosts.
 ====
 
 [[network-pxe-nfs]]
 === Setting Up the PXE Environment
 
 The steps shown in this section configure the built-in NFS and TFTP servers.
 The next section demonstrates how to install and configure the DHCP server.
 In this example, the directory which will contain the files used by PXE users is [.filename]#/b/tftpboot/FreeBSD/install#.
 It is important that this directory exists and that the same directory name is set in both [.filename]#/etc/inetd.conf# and [.filename]#/usr/local/etc/dhcpd.conf#.
 
 [NOTE]
 ====
 The command examples below assume use of the man:sh[1] shell.
 man:csh[1] and man:tcsh[1] users will need to start a man:sh[1] shell or adapt the commands to man:csh[1] syntax.
 ====
 
 [.procedure]
 . Create the root directory which will contain a FreeBSD installation to be NFS mounted:
 +
 [source,shell]
 ....
 # export NFSROOTDIR=/b/tftpboot/FreeBSD/install
 # mkdir -p ${NFSROOTDIR}
 ....
 
 . Enable the NFS server by adding this line to [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 nfs_server_enable="YES"
 ....
 
 . Export the diskless root directory via NFS by adding the following to [.filename]#/etc/exports#:
 +
 [.programlisting]
 ....
 /b -ro -alldirs -maproot=root
 ....
 
 . Start the NFS server:
 +
 [source,shell]
 ....
 # service nfsd start
 ....
 
 . Enable man:inetd[8] by adding the following line to [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 inetd_enable="YES"
 ....
 
 . Uncomment the following line in [.filename]#/etc/inetd.conf# by making sure it does not start with a `#` symbol:
 +
 [.programlisting]
 ....
 tftp dgram udp wait root /usr/libexec/tftpd tftpd -l -s /b/tftpboot
 ....
 +
 [NOTE]
 ====
 Some PXE versions require the TCP version of TFTP.
 In this case, uncomment the second `tftp` line which contains `stream tcp`.
 ====
 
 . Start man:inetd[8]:
 +
 [source,shell]
 ....
 # service inetd start
 ....
 
 . Install the base system into [.filename]#${NFSROOTDIR}#, either by decompressing the official archives or by rebuilding the FreeBSD kernel and userland (refer to crossref:cutting-edge[makeworld,“Updating FreeBSD from Source”] for more detailed instructions, but do not forget to add `DESTDIR=_${NFSROOTDIR}_` when running the `make installkernel` and `make installworld` commands.
 . Test that the TFTP server works and can download the boot loader which will be obtained via PXE:
 +
 [source,shell]
 ....
 # tftp localhost
 tftp> get FreeBSD/install/boot/pxeboot
 Received 264951 bytes in 0.1 seconds
 ....
 
 . Edit [.filename]#${NFSROOTDIR}/etc/fstab# and create an entry to mount the root file system over NFS:
 +
 [.programlisting]
 ....
 # Device                                         Mountpoint    FSType   Options  Dump Pass
 myhost.example.com:/b/tftpboot/FreeBSD/install       /         nfs      ro        0    0
 ....
-+ 
++
 Replace _myhost.example.com_ with the hostname or IP address of the NFS server.
 In this example, the root file system is mounted read-only in order to prevent NFS clients from potentially deleting the contents of the root file system.
 . Set the root password in the PXE environment for client machines which are PXE booting :
 +
 [source,shell]
 ....
 # chroot ${NFSROOTDIR}
 # passwd
 ....
 
 . If needed, enable man:ssh[1] root logins for client machines which are PXE booting by editing [.filename]#${NFSROOTDIR}/etc/ssh/sshd_config# and enabling `PermitRootLogin`. This option is documented in man:sshd_config[5].
 . Perform any other needed customizations of the PXE environment in [.filename]#${NFSROOTDIR}#. These customizations could include things like installing packages or editing the password file with man:vipw[8].
 
 When booting from an NFS root volume, [.filename]#/etc/rc# detects the NFS boot and runs [.filename]#/etc/rc.initdiskless#.
 In this case, [.filename]#/etc# and [.filename]#/var# need to be memory backed file systems so that these directories are writable but the NFS root directory is read-only:
 
 [source,shell]
 ....
 # chroot ${NFSROOTDIR}
 # mkdir -p conf/base
 # tar -c -v -f conf/base/etc.cpio.gz --format cpio --gzip etc
 # tar -c -v -f conf/base/var.cpio.gz --format cpio --gzip var
 ....
 
 When the system boots, memory file systems for [.filename]#/etc# and [.filename]#/var# will be created and mounted and the contents of the [.filename]#cpio.gz# files will be copied into them.
 By default, these file systems have a maximum capacity of 5 megabytes.
 If your archives do not fit, which is usually the case for [.filename]#/var# when binary packages have been installed, request a larger size by putting the number of 512 byte sectors needed (e.g., 5 megabytes is 10240 sectors) in [.filename]#${NFSROOTDIR}/conf/base/etc/md_size# and [.filename]#${NFSROOTDIR}/conf/base/var/md_size# files for [.filename]#/etc# and [.filename]#/var# file systems respectively.
 
 [[network-pxe-setting-up-dhcp]]
 === Configuring the DHCP Server
 
 The DHCP server does not need to be the same machine as the TFTP and NFS server, but it needs to be accessible in the network.
 
 DHCP is not part of the FreeBSD base system but can be installed using the package:net/isc-dhcp43-server[] port or package.
 
 Once installed, edit the configuration file, [.filename]#/usr/local/etc/dhcpd.conf#.
 Configure the `next-server`, `filename`, and `root-path` settings as seen in this example:
 
 [.programlisting]
 ....
 subnet 192.168.0.0 netmask 255.255.255.0 {
    range 192.168.0.2 192.168.0.3 ;
    option subnet-mask 255.255.255.0 ;
    option routers 192.168.0.1 ;
    option broadcast-address 192.168.0.255 ;
    option domain-name-servers 192.168.35.35, 192.168.35.36 ;
    option domain-name "example.com";
 
    # IP address of TFTP server
    next-server 192.168.0.1 ;
 
    # path of boot loader obtained via tftp
    filename "FreeBSD/install/boot/pxeboot" ;
 
    # pxeboot boot loader will try to NFS mount this directory for root FS
    option root-path "192.168.0.1:/b/tftpboot/FreeBSD/install/" ;
 
 }
 ....
 
 The `next-server` directive is used to specify the IP address of the TFTP server.
 
 The `filename` directive defines the path to [.filename]#/boot/pxeboot#.
 A relative filename is used, meaning that [.filename]#/b/tftpboot# is not included in the path.
 
 The `root-path` option defines the path to the NFS root file system.
 
 Once the edits are saved, enable DHCP at boot time by adding the following line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 dhcpd_enable="YES"
 ....
 
 Then start the DHCP service:
 
 [source,shell]
 ....
 # service isc-dhcpd start
 ....
 
 === Debugging PXE Problems
 
 Once all of the services are configured and started, PXE clients should be able to automatically load FreeBSD over the network.
 If a particular client is unable to connect, when that client machine boots up, enter the BIOS configuration menu and confirm that it is set to boot from the network.
 
 This section describes some troubleshooting tips for isolating the source of the configuration problem should no clients be able to PXE boot.
 
 [.procedure]
 ****
 . Use the package:net/wireshark[] package or port to debug the network traffic involved during the PXE booting process, which is illustrated in the diagram below.
 +
 .PXE Booting Process with NFS Root Mount
 image::pxe-nfs.png[]
 +
 1. Client broadcasts a DHCPDISCOVER message.
 +
 2. The DHCP server responds with the IP address, next-server, filename, and root-path values.
 +
 3. The client sends a TFTP request to next-server, asking to retrieve filename.
 +
 4. The TFTP server responds and sends filename to client.
 +
 5. The client executes filename, which is pxeboot(8), which then loads the kernel. When the kernel executes, the root file system specified by root-path is mounted over NFS.
 +
 . On the TFTP server, read [.filename]#/var/log/xferlog# to ensure that [.filename]#pxeboot# is being retrieved from the correct location. To test this example configuration:
 +
 [source,shell]
 ....
 # tftp 192.168.0.1
 tftp> get FreeBSD/install/boot/pxeboot
 Received 264951 bytes in 0.1 seconds
 ....
-+ 
++
 The `BUGS` sections in man:tftpd[8] and man:tftp[1] document some limitations with TFTP.
 . Make sure that the root file system can be mounted via NFS. To test this example configuration:
 +
 [source,shell]
 ....
 # mount -t nfs 192.168.0.1:/b/tftpboot/FreeBSD/install /mnt
 ....
 ****
 
 [[network-ipv6]]
 == IPv6
 
 IPv6 is the new version of the well known IP protocol, also known as IPv4.
 IPv6 provides several advantages over IPv4 as well as many new features:
 
 * Its 128-bit address space allows for 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses. This addresses the IPv4 address shortage and eventual IPv4 address exhaustion.
 * Routers only store network aggregation addresses in their routing tables, thus reducing the average space of a routing table to 8192 entries. This addresses the scalability issues associated with IPv4, which required every allocated block of IPv4 addresses to be exchanged between Internet routers, causing their routing tables to become too large to allow efficient routing.
 
 * Address autoconfiguration (http://www.ietf.org/rfc/rfc2462.txt[RFC2462]).
 * Mandatory multicast addresses.
 * Built-in IPsec (IP security).
 * Simplified header structure.
 * Support for mobile IP.
 * IPv6-to-IPv4 transition mechanisms.
 
 FreeBSD includes the http://www.kame.net/[http://www.kame.net/] IPv6 reference implementation and comes with everything needed to use IPv6.
 This section focuses on getting IPv6 configured and running.
 
 === Background on IPv6 Addresses
 
 There are three different types of IPv6 addresses:
 
 Unicast::
 A packet sent to a unicast address arrives at the interface belonging to the address.
 
 Anycast::
 These addresses are syntactically indistinguishable from unicast addresses but they address a group of interfaces.
 The packet destined for an anycast address will arrive at the nearest router interface.
 Anycast addresses are only used by routers.
 
 Multicast::
 These addresses identify a group of interfaces.
 A packet destined for a multicast address will arrive at all interfaces belonging to the multicast group.
 The IPv4 broadcast address, usually `xxx.xxx.xxx.255`, is expressed by multicast addresses in IPv6.
 
 When reading an IPv6 address, the canonical form is represented as `x:x:x:x:x:x:x:x`, where each `x` represents a 16 bit hex value.
 An example is `FEBC:A574:382B:23C1:AA49:4592:4EFE:9982`.
 
 Often, an address will have long substrings of all zeros.
 A `::` (double colon) can be used to replace one substring per address.
 Also, up to three leading ``0``s per hex value can be omitted.
 For example, `fe80::1` corresponds to the canonical form `fe80:0000:0000:0000:0000:0000:0000:0001`.
 
 A third form is to write the last 32 bits using the well known IPv4 notation.
 For example, `2002::10.0.0.1` corresponds to the hexadecimal canonical representation `2002:0000:0000:0000:0000:0000:0a00:0001`, which in turn is equivalent to `2002::a00:1`.
 
 To view a FreeBSD system's IPv6  address, use man:ifconfig[8]:
 
 [source,shell]
 ....
 # ifconfig
 ....
 
 [.programlisting]
 ....
 rl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
          inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255
          inet6 fe80::200:21ff:fe03:8e1%rl0 prefixlen 64 scopeid 0x1
          ether 00:00:21:03:08:e1
          media: Ethernet autoselect (100baseTX )
          status: active
 ....
 
 In this example, the [.filename]#rl0# interface is using `fe80::200:21ff:fe03:8e1%rl0`, an auto-configured link-local address which was automatically generated from the MAC address.
 
 Some IPv6 addresses are reserved.
 A summary of these reserved addresses is seen in <<reservedip6>>:
 
 [[reservedip6]]
 .Reserved IPv6 Addresses
 [cols="1,1,1,1", frame="none", options="header"]
 |===
 | IPv6 address
 | Prefixlength (Bits)
 | Description
 | Notes
 
 |`::`
 |128 bits
 |unspecified
 |Equivalent to `0.0.0.0` in IPv4.
 
 |`::1`
 |128 bits
 |loopback address
 |Equivalent to `127.0.0.1` in IPv4.
 
 |`::00:xx:xx:xx:xx`
 |96 bits
 |embedded IPv4
 |The lower 32 bits are the compatible IPv4 address.
 
 |`::ff:xx:xx:xx:xx`
 |96 bits
 |IPv4 mapped IPv6 address
 |The lower 32 bits are the IPv4 address for hosts which do not support IPv6.
 
 |`fe80::/10`
 |10 bits
 |link-local
 |Equivalent to 169.254.0.0/16 in IPv4.
 
 |`fc00::/7`
 |7 bits
 |unique-local
 |Unique local addresses are intended for local communication and are only routable within a set of cooperating sites.
 
 |`ff00::`
 |8 bits
 |multicast
 |
 
 |``2000::-3fff::``
 |3 bits
 |global unicast
 |All global unicast addresses are assigned from this pool. The first 3 bits are `001`.
 |===
 
 For further information on the structure of IPv6 addresses, refer to http://www.ietf.org/rfc/rfc3513.txt[RFC3513].
 
 === Configuring IPv6
 
 To configure a FreeBSD system as an IPv6 client, add these two lines to [.filename]#rc.conf#:
 
 [.programlisting]
 ....
 ifconfig_rl0_ipv6="inet6 accept_rtadv"
 rtsold_enable="YES"
 ....
 
 The first line enables the specified interface to receive router advertisement messages.
 The second line enables the router solicitation daemon, man:rtsol[8].
 
 If the interface needs a statically assigned IPv6 address, add an entry to specify the static address and associated prefix length:
 
 [.programlisting]
 ....
 ifconfig_rl0_ipv6="inet6 2001:db8:4672:6565:2026:5043:2d42:5344 prefixlen 64"
 ....
 
 To assign a default router, specify its address:
 
 [.programlisting]
 ....
 ipv6_defaultrouter="2001:db8:4672:6565::1"
 ....
 
 === Connecting to a Provider
 
 In order to connect to other IPv6 networks, one must have a provider or a tunnel that supports IPv6:
 
 * Contact an Internet Service Provider to see if they offer IPv6.
 * http://www.tunnelbroker.net[Hurricane Electric] offers tunnels with end-points all around the globe.
 
 [NOTE]
 ====
 Install the package:net/freenet6[] package or port for a dial-up connection.
 ====
 
 This section demonstrates how to take the directions from a tunnel provider and convert them into [.filename]#/etc/rc.conf# settings that will persist through reboots.
 
 The first [.filename]#/etc/rc.conf# entry creates the generic tunneling interface [.filename]#gif0#:
 
 [.programlisting]
 ....
 cloned_interfaces="gif0"
 ....
 
 Next, configure that interface with the IPv4 addresses of the local and remote endpoints.
 Replace `_MY_IPv4_ADDR_` and `_REMOTE_IPv4_ADDR_` with the actual IPv4 addresses:
 
 [.programlisting]
 ....
 create_args_gif0="tunnel MY_IPv4_ADDR REMOTE_IPv4_ADDR"
 ....
 
 To apply the IPv6 address that has been assigned for use as the IPv6 tunnel endpoint, add this line, replacing `_MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR_` with the assigned address:
 
 [.programlisting]
 ....
 ifconfig_gif0_ipv6="inet6 MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR"
 ....
 
 Then, set the default route for the other side of the IPv6 tunnel.
 Replace `_MY_IPv6_REMOTE_TUNNEL_ENDPOINT_ADDR_` with the default gateway address assigned by the provider:
 
 [.programlisting]
 ....
 ipv6_defaultrouter="MY_IPv6_REMOTE_TUNNEL_ENDPOINT_ADDR"
 ....
 
 If the FreeBSD system will route IPv6 packets between the rest of the network and the world, enable the gateway using this line:
 
 [.programlisting]
 ....
 ipv6_gateway_enable="YES"
 ....
 
 === Router Advertisement and Host Auto Configuration
 
 This section demonstrates how to setup man:rtadvd[8] to advertise the IPv6 default route.
 
 To enable man:rtadvd[8], add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 rtadvd_enable="YES"
 ....
 
 It is important to specify the interface on which to do IPv6 router advertisement.
 For example, to tell man:rtadvd[8] to use [.filename]#rl0#:
 
 [.programlisting]
 ....
 rtadvd_interfaces="rl0"
 ....
 
 Next, create the configuration file, [.filename]#/etc/rtadvd.conf# as seen in this example:
 
 [.programlisting]
 ....
 rl0:\
 	:addrs#1:addr="2001:db8:1f11:246::":prefixlen#64:tc=ether:
 ....
 
 Replace [.filename]#rl0# with the interface to be used and `2001:db8:1f11:246::` with the prefix of the allocation.
 
 For a dedicated `/64` subnet, nothing else needs to be changed.
 Otherwise, change the `prefixlen#` to the correct value.
 
 === IPv6 and IPv6 Address Mapping
 
 When IPv6 is enabled on a server, there may be a need to enable IPv4 mapped IPv6 address communication.
 This compatibility option allows for IPv4 addresses to be represented as IPv6 addresses.
 Permitting IPv6 applications to communicate with IPv4 and vice versa may be a security issue.
 
 This option may not be required in most cases and is available only for compatibility.
 This option will allow IPv6-only applications to work with IPv4 in a dual stack environment.
 This is most useful for third party applications which may not support an IPv6-only environment.
 To enable this feature, add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 ipv6_ipv4mapping="YES"
 ....
 
 Reviewing the information in RFC 3493, section 3.6 and 3.7 as well as RFC 4038 section 4.2 may be useful to some administrators.
 
 [[carp]]
 == Common Address Redundancy Protocol (CARP)
 
 The Common Address Redundancy Protocol (CARP) allows multiple hosts to share the same IP address and Virtual Host ID (VHID) in order to provide _high availability_ for one or more services.
 This means that one or more hosts can fail, and the other hosts will transparently take over so that users do not see a service failure.
 
 In addition to the shared IP address, each host has its own IP address for management and configuration.
 All of the machines that share an IP address have the same VHID.
 The VHID for each virtual IP address must be unique across the broadcast domain of the network interface.
 
 High availability using CARP is built into FreeBSD, though the steps to configure it vary slightly depending upon the FreeBSD version.
 This section provides the same example configuration for versions before and equal to or after FreeBSD 10.
 
 This example configures failover support with three hosts, all with unique IP addresses, but providing the same web content.
 It has two different masters named `hosta.example.org` and `hostb.example.org`, with a shared backup named `hostc.example.org`.
 
 These machines are load balanced with a Round Robin DNS configuration.
 The master and backup machines are configured identically except for their hostnames and management IP addresses.
 These servers must have the same configuration and run the same services.
 When the failover occurs, requests to the service on the shared IP address can only be answered correctly if the backup server has access to the same content.
 The backup machine has two additional CARP interfaces, one for each of the master content server's IP addresses.
 When a failure occurs, the backup server will pick up the failed master machine's IP address.
 
 [[carp-10x]]
 === Using CARP on FreeBSD 10 and Later
 
 Enable boot-time support for CARP by adding an entry for the [.filename]#carp.ko# kernel module in [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 carp_load="YES"
 ....
 
 To load the module now without rebooting:
 
 [source,shell]
 ....
 # kldload carp
 ....
 
 For users who prefer to use a custom kernel, include the following line in the custom kernel configuration file and compile the kernel as described in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel]:
 
 [.programlisting]
 ....
 device	carp
 ....
 
 The hostname, management IP address and subnet mask, shared IP address, and VHID are all set by adding entries to [.filename]#/etc/rc.conf#. This example is for `hosta.example.org`:
 
 [.programlisting]
 ....
 hostname="hosta.example.org"
 ifconfig_em0="inet 192.168.1.3 netmask 255.255.255.0"
 ifconfig_em0_alias0="inet vhid 1 pass testpass alias 192.168.1.50/32"
 ....
 
 The next set of entries are for `hostb.example.org`.
 Since it represents a second master, it uses a different shared IP address and VHID.
 However, the passwords specified with `pass` must be identical as CARP will only listen to and accept advertisements from machines with the correct password.
 
 [.programlisting]
 ....
 hostname="hostb.example.org"
 ifconfig_em0="inet 192.168.1.4 netmask 255.255.255.0"
 ifconfig_em0_alias0="inet vhid 2 pass testpass alias 192.168.1.51/32"
 ....
 
 The third machine, `hostc.example.org`, is configured to handle failover from either master.
 This machine is configured with two CARPVHIDs, one to handle the virtual IP address for each of the master hosts.
 The CARP advertising skew, `advskew`, is set to ensure that the backup host advertises later than the master, since `advskew` controls the order of precedence when there are multiple backup servers.
 
 [.programlisting]
 ....
 hostname="hostc.example.org"
 ifconfig_em0="inet 192.168.1.5 netmask 255.255.255.0"
 ifconfig_em0_alias0="inet vhid 1 advskew 100 pass testpass alias 192.168.1.50/32"
 ifconfig_em0_alias1="inet vhid 2 advskew 100 pass testpass alias 192.168.1.51/32"
 ....
 
 Having two CARPVHIDs configured means that `hostc.example.org` will notice if either of the master servers becomes unavailable.
 If a master fails to advertise before the backup server, the backup server will pick up the shared IP address until the master becomes available again.
 
 [NOTE]
 ====
 If the original master server becomes available again, `hostc.example.org` will not release the virtual IP address back to it automatically.
 For this to happen, preemption has to be enabled.
 The feature is disabled by default, it is controlled via the man:sysctl[8] variable `net.inet.carp.preempt`.
 The administrator can force the backup server to return the IP address to the master:
 
 [source,shell]
 ....
 # ifconfig em0 vhid 1 state backup
 ....
 
 ====
 
 Once the configuration is complete, either restart networking or reboot each system.
 High availability is now enabled.
 
 CARP functionality can be controlled via several man:sysctl[8] variables documented in the man:carp[4] manual pages.
 Other actions can be triggered from CARP events by using man:devd[8].
 
 [[carp-9x]]
 === Using CARP on FreeBSD 9 and Earlier
 
 The configuration for these versions of FreeBSD is similar to the one described in the previous section, except that a CARP device must first be created and referred to in the configuration.
 
 Enable boot-time support for CARP by loading the [.filename]#if_carp.ko# kernel module in [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 if_carp_load="YES"
 ....
 
 To load the module now without rebooting:
 
 [source,shell]
 ....
 # kldload carp
 ....
 
 For users who prefer to use a custom kernel, include the following line in the custom kernel configuration file and compile the kernel as described in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel]:
 
 [.programlisting]
 ....
 device	carp
 ....
 
 Next, on each host, create a CARP device:
 
 [source,shell]
 ....
 # ifconfig carp0 create
 ....
 
 Set the hostname, management IP address, the shared IP address, and VHID by adding the required lines to [.filename]#/etc/rc.conf#.
 Since a virtual CARP device is used instead of an alias, the actual subnet mask of `/24` is used instead of `/32`.
 Here are the entries for `hosta.example.org`:
 
 [.programlisting]
 ....
 hostname="hosta.example.org"
 ifconfig_fxp0="inet 192.168.1.3 netmask 255.255.255.0"
 cloned_interfaces="carp0"
 ifconfig_carp0="vhid 1 pass testpass 192.168.1.50/24"
 ....
 
 On `hostb.example.org`:
 
 [.programlisting]
 ....
 hostname="hostb.example.org"
 ifconfig_fxp0="inet 192.168.1.4 netmask 255.255.255.0"
 cloned_interfaces="carp0"
 ifconfig_carp0="vhid 2 pass testpass 192.168.1.51/24"
 ....
 
 The third machine, `hostc.example.org`, is configured to handle failover from either of the master hosts:
 
 [.programlisting]
 ....
 hostname="hostc.example.org"
 ifconfig_fxp0="inet 192.168.1.5 netmask 255.255.255.0"
 cloned_interfaces="carp0 carp1"
 ifconfig_carp0="vhid 1 advskew 100 pass testpass 192.168.1.50/24"
 ifconfig_carp1="vhid 2 advskew 100 pass testpass 192.168.1.51/24"
 ....
 
 [NOTE]
 ====
 Preemption is disabled in the [.filename]#GENERIC# FreeBSD kernel.
 If preemption has been enabled with a custom kernel, `hostc.example.org` may not release the IP address back to the original content server.
 The administrator can force the backup server to return the IP address to the master with the command:
 
 [source,shell]
 ....
 # ifconfig carp0 down && ifconfig carp0 up
 ....
 
 This should be done on the [.filename]#carp# interface which corresponds to the correct host.
 ====
 
 Once the configuration is complete, either restart networking or reboot each system.
 High availability is now enabled.
 
 [[network-vlan]]
 == VLANs
 
 VLANs are a way of virtually dividing up a network into many different subnetworks, also referred to as segmenting.
 Each segment will have its own broadcast domain and be isolated from other VLANs.
 
 On FreeBSD, VLANs must be supported by the network card driver.
 To see which drivers support vlans, refer to the man:vlan[4] manual page.
 
 When configuring a VLAN, a couple pieces of information must be known.
 First, which network interface? Second, what is the VLAN tag?
 
 To configure VLANs at run time, with a NIC of `em0` and a VLAN tag of `5` the command would look like this:
 
 [source,shell]
 ....
 # ifconfig em0.5 create vlan 5 vlandev em0 inet 192.168.20.20/24
 ....
 
 [NOTE]
 ====
 See how the interface name includes the NIC driver name and the VLAN tag, separated by a period? This is a best practice to make maintaining the VLAN configuration easy when many VLANs are present on a machine.
 ====
 
 To configure VLANs at boot time, [.filename]#/etc/rc.conf# must be updated.
 To duplicate the configuration above, the following will need to be added:
 
 [.programlisting]
 ....
 vlans_em0="5"
 ifconfig_em0_5="inet 192.168.20.20/24"
 ....
 
 Additional VLANs may be added, by simply adding the tag to the `vlans_em0` field and adding an additional line configuring the network on that VLAN tag's interface.
 
 It is useful to assign a symbolic name to an interface so that when the associated hardware is changed, only a few configuration variables need to be updated.
 For example, security cameras need to be run over VLAN 1 on `em0`.
 Later, if the `em0` card is replaced with a card that uses the man:ixgb[4] driver, all references to `em0.1` will not have to change to `ixgb0.1`.
 
 To configure VLAN `5`, on the NIC `em0`, assign the interface name `cameras`, and assign the interface an IP address of `_192.168.20.20_` with a `24`-bit prefix, use this command:
 
 [source,shell]
 ....
 # ifconfig em0.5 create vlan 5 vlandev em0 name cameras inet 192.168.20.20/24
 ....
 
 For an interface named `video`, use the following:
 
 [source,shell]
 ....
 # ifconfig video.5 create vlan 5 vlandev video name cameras inet 192.168.20.20/24
 ....
 
 To apply the changes at boot time, add the following lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 vlans_video="cameras"
 create_args_cameras="vlan 5"
 ifconfig_cameras="inet 192.168.20.20/24"
 ....
diff --git a/documentation/content/en/books/handbook/bibliography/_index.adoc b/documentation/content/en/books/handbook/bibliography/_index.adoc
index f09c867678..6d990d7712 100644
--- a/documentation/content/en/books/handbook/bibliography/_index.adoc
+++ b/documentation/content/en/books/handbook/bibliography/_index.adoc
@@ -1,151 +1,151 @@
 ---
 title: Appendix B. Bibliography
 part: Part V. Appendices
 prev: books/handbook/mirrors
 next: books/handbook/eresources
 description: FreeBSD Handbook Bibliography
 tags: ["appendix", "bibliography", "handbook", "books", "guides", "security", "periodicals", "journals", "magazines"]
 ---
 
 [appendix]
 [[bibliography]]
 = Bibliography
 :doctype: book
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: B
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 While manual pages provide a definitive reference for individual pieces of the FreeBSD operating system, they seldom illustrate how to put the pieces together to make the whole operating system run smoothly.
 For this, there is no substitute for a good book or users' manual on UNIX(R) system administration.
 
 [[bibliography-freebsd]]
 == Books Specific to FreeBSD
 
 International books:
 
 * http://jdli.tw.FreeBSD.org/publication/book/freebsd2/index.htm[Using FreeBSD] (in Traditional Chinese), published by http://www.drmaster.com.tw/[Drmaster], 1997. ISBN 9-578-39435-7.
 * FreeBSD Unleashed (Simplified Chinese translation), published by http://www.hzbook.com/[China Machine Press]. ISBN 7-111-10201-0.
 * FreeBSD From Scratch Second Edition (in Simplified Chinese), published by China Machine Press. ISBN 7-111-10286-X.
 * FreeBSD Handbook Second Edition (Simplified Chinese translation), published by http://www.ptpress.com.cn/[Posts & Telecom Press]. ISBN 7-115-10541-3.
 * FreeBSD & Windows (in Simplified Chinese), published by http://www.tdpress.com/[China Railway Publishing House]. ISBN 7-113-03845-X
 * FreeBSD Internet Services HOWTO (in Simplified Chinese), published by China Railway Publishing House. ISBN 7-113-03423-3
 * FreeBSD (in Japanese), published by CUTT. ISBN 4-906391-22-2 C3055 P2400E.
 * http://www.shoeisha.com/book/Detail.asp?bid=650[Complete Introduction to FreeBSD] (in Japanese), published by http://www.shoeisha.co.jp/[Shoeisha Co., Ltd]. ISBN 4-88135-473-6 P3600E.
 * http://www.ascii.co.jp/pb/book1/shinkan/detail/1322785.html[Personal UNIX Starter Kit FreeBSD] (in Japanese), published by http://www.ascii.co.jp/[ASCII]. ISBN 4-7561-1733-3 P3000E.
 * FreeBSD Handbook (Japanese translation), published by http://www.ascii.co.jp/[ASCII]. ISBN 4-7561-1580-2 P3800E.
 * FreeBSD mit Methode (in German), published by http://www.cul.de[Computer und Literatur Verlag]/Vertrieb Hanser, 1998. ISBN 3-932311-31-0.
 * http://www.mitp.de/vmi/mitp/detail/pWert/1343/[FreeBSD de Luxe] (in German), published by http://www.mitp.de[Verlag Modere Industrie], 2003. ISBN 3-8266-1343-0.
 * http://www.pc.mycom.co.jp/FreeBSD/install-manual.html[FreeBSD Install and Utilization Manual] (in Japanese), published by http://www.pc.mycom.co.jp/[Mainichi Communications Inc.], 1998. ISBN 4-8399-0112-0.
 * Onno W Purbo, Dodi Maryanto, Syahrial Hubbany, Widjil Widodo _http://maxwell.itb.ac.id/[Building Internet Server with FreeBSD]_ (in Indonesia Language), published by http://www.elexmedia.co.id/[Elex Media Komputindo].
 * Absolute BSD: The Ultimate Guide to FreeBSD (Traditional Chinese translation), published by http://www.grandtech.com.tw/[GrandTech Press], 2003. ISBN 986-7944-92-5.
 * http://www.twbsd.org/cht/book/[The FreeBSD 6.0 Book] (in Traditional Chinese), published by Drmaster, 2006. ISBN 9-575-27878-X.
 
 English language books:
 
 * http://www.absoluteFreeBSD.com/[Absolute FreeBSD, 2nd Edition: The Complete Guide to FreeBSD], published by http://www.nostarch.com/[No Starch Press], 2007. ISBN: 978-1-59327-151-0
 * http://www.freebsdmall.com/cgi-bin/fm/bsdcomp[The Complete FreeBSD], published by http://www.oreilly.com/[O'Reilly], 2003. ISBN: 0596005164
 * http://www.freebsd-corp-net-guide.com/[The FreeBSD Corporate Networker's Guide], published by http://www.awl.com/aw/[Addison-Wesley], 2000. ISBN: 0201704811
 * http://andrsn.stanford.edu/FreeBSD/introbook/[FreeBSD: An Open-Source Operating System for Your Personal Computer], published by The Bit Tree Press, 2001. ISBN: 0971204500
 * Teach Yourself FreeBSD in 24 Hours, published by http://www.samspublishing.com/[Sams], 2002. ISBN: 0672324245
 * FreeBSD 6 Unleashed, published by http://www.samspublishing.com/[Sams], 2006. ISBN: 0672328755
 * FreeBSD: The Complete Reference, published by http://books.mcgraw-hill.com[McGrawHill], 2003. ISBN: 0072224096
 
 [[bibliography-userguides]]
 == Users' Guides
 
 * Ohio State University has written a http://www.cs.duke.edu/csl/docs/unix_course/[UNIX Introductory Course] which is available online in HTML and PostScript format.
-+ 
++
 An Italian https://www.FreeBSD.org/doc/it_IT.ISO8859-15/books/unix-introduction/[translation] of this document is available as part of the FreeBSD Italian Documentation Project.
 * http://www.jp.FreeBSD.org/[Jpman Project, Japan FreeBSD Users Group]. FreeBSD User's Reference Manual (Japanese translation). http://www.pc.mycom.co.jp/[Mainichi Communications Inc.], 1998. ISBN4-8399-0088-4 P3800E.
 * http://www.ed.ac.uk/[Edinburgh University] has written an http://www.ed.ac.uk/information-services/help-consultancy/is-skills/catalogue/program-op-sys-catalogue/unix1[Online Guide] for newcomers to the UNIX environment.
 
 [[bibliography-adminguides]]
 == Administrators' Guides
 
 * http://www.jp.FreeBSD.org/[Jpman Project, Japan FreeBSD Users Group]. FreeBSD System Administrator's Manual (Japanese translation). http://www.pc.mycom.co.jp/[Mainichi Communications Inc.], 1998. ISBN4-8399-0109-0 P3300E.
 * Dreyfus, Emmanuel. http://www.eyrolles.com/Informatique/Livre/9782212114638/[Cahiers de l'Admin: BSD] 2nd Ed. (in French), Eyrolles, 2004. ISBN 2-212-11463-X
 
 [[bibliography-programmers]]
 == Programmers' Guides
 
 * Computer Systems Research Group, UC Berkeley. _4.4BSD Programmer's Reference Manual_. O'Reilly & Associates, Inc., 1994. ISBN 1-56592-078-3
 * Computer Systems Research Group, UC Berkeley. _4.4BSD Programmer's Supplementary Documents_. O'Reilly & Associates, Inc., 1994. ISBN 1-56592-079-1
 * Harbison, Samuel P. and Steele, Guy L. Jr. _C: A Reference Manual_. 4th Ed. Prentice Hall, 1995. ISBN 0-13-326224-3
 * Kernighan, Brian and Dennis M. Ritchie. _The C Programming Language_. 2nd Ed. PTR Prentice Hall, 1988. ISBN 0-13-110362-8
 * Lehey, Greg. _Porting UNIX Software_. O'Reilly & Associates, Inc., 1995. ISBN 1-56592-126-7
 * Plauger, P. J. _The Standard C Library_. Prentice Hall, 1992. ISBN 0-13-131509-9
 * Spinellis, Diomidis. http://www.spinellis.gr/codereading/[Code Reading: The Open Source Perspective]. Addison-Wesley, 2003. ISBN 0-201-79940-5
 * Spinellis, Diomidis. http://www.spinellis.gr/codequality/[Code Quality: The Open Source Perspective]. Addison-Wesley, 2006. ISBN 0-321-16607-8
 * Stevens, W. Richard and Stephen A. Rago. _Advanced Programming in the UNIX Environment_. 2nd Ed. Reading, Mass. : Addison-Wesley, 2005. ISBN 0-201-43307-9
 * Stevens, W. Richard. _UNIX Network Programming_. 2nd Ed, PTR Prentice Hall, 1998. ISBN 0-13-490012-X
 
 [[bibliography-osinternals]]
 == Operating System Internals
 
 * Andleigh, Prabhat K. _UNIX System Architecture_. Prentice-Hall, Inc., 1990. ISBN 0-13-949843-5
 * Jolitz, William. "Porting UNIX to the 386". _Dr. Dobb's Journal_. January 1991-July 1992.
 * Leffler, Samuel J., Marshall Kirk McKusick, Michael J Karels and John Quarterman _The Design and Implementation of the 4.3BSD UNIX Operating System_. Reading, Mass. : Addison-Wesley, 1989. ISBN 0-201-06196-1
 * Leffler, Samuel J., Marshall Kirk McKusick, _The Design and Implementation of the 4.3BSD UNIX Operating System: Answer Book_. Reading, Mass. : Addison-Wesley, 1991. ISBN 0-201-54629-9
 * McKusick, Marshall Kirk, Keith Bostic, Michael J Karels, and John Quarterman. _The Design and Implementation of the 4.4BSD Operating System_. Reading, Mass. : Addison-Wesley, 1996. ISBN 0-201-54979-4
-+ 
++
 (Chapter 2 of this book is available link:{design-44bsd}[online] as part of the FreeBSD Documentation Project.)
 * Marshall Kirk McKusick, George V. Neville-Neil _The Design and Implementation of the FreeBSD Operating System_. Boston, Mass. : Addison-Wesley, 2004. ISBN 0-201-70245-2
 * Marshall Kirk McKusick, George V. Neville-Neil, Robert N. M. Watson _The Design and Implementation of the FreeBSD Operating System, 2nd Ed._. Westford, Mass. : Pearson Education, Inc., 2014. ISBN 0-321-96897-2
 * Stevens, W. Richard. _TCP/IP Illustrated, Volume 1: The Protocols_. Reading, Mass. : Addison-Wesley, 1996. ISBN 0-201-63346-9
 * Schimmel, Curt. _Unix Systems for Modern Architectures_. Reading, Mass. : Addison-Wesley, 1994. ISBN 0-201-63338-8
 * Stevens, W. Richard. _TCP/IP Illustrated, Volume 3: TCP for Transactions, HTTP, NNTP and the UNIX Domain Protocols_. Reading, Mass. : Addison-Wesley, 1996. ISBN 0-201-63495-3
 * Vahalia, Uresh. _UNIX Internals -- The New Frontiers_. Prentice Hall, 1996. ISBN 0-13-101908-2
 * Wright, Gary R. and W. Richard Stevens. _TCP/IP Illustrated, Volume 2: The Implementation_. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-63354-X
 
 [[bibliography-security]]
 == Security Reference
 
 * Cheswick, William R. and Steven M. Bellovin. _Firewalls and Internet Security: Repelling the Wily Hacker_. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-63357-4
 * Garfinkel, Simson. _PGP Pretty Good Privacy_ O'Reilly & Associates, Inc., 1995. ISBN 1-56592-098-8
 
 [[bibliography-hardware]]
 == Hardware Reference
 
 * Anderson, Don and Tom Shanley. _Pentium Processor System Architecture_. 2nd Ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-40992-5
 * Ferraro, Richard F. _Programmer's Guide to the EGA, VGA, and Super VGA Cards_. 3rd ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-62490-7
 * Intel Corporation publishes documentation on their CPUs, chipsets and standards on their http://developer.intel.com/[developer web site], usually as PDF files.
 * Shanley, Tom. _80486 System Architecture_. 3rd Ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-40994-1
 * Shanley, Tom. _ISA System Architecture_. 3rd Ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-40996-8
 * Shanley, Tom. _PCI System Architecture_. 4th Ed. Reading, Mass. : Addison-Wesley, 1999. ISBN 0-201-30974-2
 * Van Gilluwe, Frank. _The Undocumented PC_, 2nd Ed. Reading, Mass: Addison-Wesley Pub. Co., 1996. ISBN 0-201-47950-8
 * Messmer, Hans-Peter. _The Indispensable PC Hardware Book_, 4th Ed. Reading, Mass : Addison-Wesley Pub. Co., 2002. ISBN 0-201-59616-4
 
 [[bibliography-history]]
 == UNIX(R) History
 
 * Lion, John _Lion's Commentary on UNIX, 6th Ed. With Source Code_. ITP Media Group, 1996. ISBN 1573980137
 * Raymond, Eric S. _The New Hacker's Dictionary, 3rd edition_. MIT Press, 1996. ISBN 0-262-68092-0. Also known as the http://www.catb.org/~esr/jargon/html/index.html[Jargon File]
 * Salus, Peter H. _A quarter century of UNIX_. Addison-Wesley Publishing Company, Inc., 1994. ISBN 0-201-54777-5
 * Simon Garfinkel, Daniel Weise, Steven Strassmann. _The UNIX-HATERS Handbook_. IDG Books Worldwide, Inc., 1994. ISBN 1-56884-203-1. Out of print, but available http://www.simson.net/ref/ugh.pdf[online].
 * Don Libes, Sandy Ressler _Life with UNIX_ - special edition. Prentice-Hall, Inc., 1989. ISBN 0-13-536657-7
 * _The BSD family tree_. https://cgit.freebsd.org/src/tree/share/misc/bsd-family-tree[https://cgit.freebsd.org/src/tree/share/misc/bsd-family-tree] or link:file://localhost/usr/share/misc/bsd-family-tree[/usr/share/misc/bsd-family-tree] on a FreeBSD machine.
 * _Networked Computer Science Technical Reports Library_.
 * _Old BSD releases from the Computer Systems Research group (CSRG)_. http://www.mckusick.com/csrg/[http://www.mckusick.com/csrg/]: The 4CD set covers all BSD versions from 1BSD to 4.4BSD and 4.4BSD-Lite2 (but not 2.11BSD, unfortunately). The last disk also holds the final sources plus the SCCS files.
 * Kernighan, Brian _Unix: A History and a Memoir_.  Kindle Direct Publishing, 2020.  ISBN 978-169597855-3
 
 [[bibliography-journals]]
 == Periodicals, Journals, and Magazines
 
 * http://www.admin-magazin.de/[Admin Magazin] (in German), published by Medialinx AG. ISSN: 2190-1066
 * http://www.bsdmag.org/[BSD Magazine], published by Software Press Sp. z o.o. SK. ISSN: 1898-9144
 * http://www.bsdnow.tv/[BSD Now - Video Podcast], published by Jupiter Broadcasting LLC
 * http://bsdtalk.blogspot.com/[BSD Talk Podcast], by Will Backman
 * http://freebsdjournal.com/[FreeBSD Journal], published by S&W Publishing, sponsored by The FreeBSD Foundation. ISBN: 978-0-615-88479-0
diff --git a/documentation/content/en/books/handbook/bsdinstall/_index.adoc b/documentation/content/en/books/handbook/bsdinstall/_index.adoc
index cd11a7f59e..5c09b033c6 100644
--- a/documentation/content/en/books/handbook/bsdinstall/_index.adoc
+++ b/documentation/content/en/books/handbook/bsdinstall/_index.adoc
@@ -1,1292 +1,1292 @@
 ---
 title: Chapter 2. Installing FreeBSD
 part: Part I. Getting Started
 prev: books/handbook/introduction
 next: books/handbook/basics
 description: Guide about how to install FreeBSD, the minimum hardware requirements and supported architectures, how to create the installation media, etc
 tags: ["bsdinstall", "installing FreeBSD", "requirements", "tutorial", "guide"]
 ---
 
 [[bsdinstall]]
 = Installing FreeBSD
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 toc::[]
 
 [[bsdinstall-synopsis]]
 == Synopsis
 
 There are several different ways of getting FreeBSD to run, depending on the environment.
 Those are:
 
 * Virtual Machine images, to download and import on a virtual environment of choice. These can be downloaded from the https://www.freebsd.org/where/[Download FreeBSD] page. There are images for KVM ("qcow2"), VMWare ("vmdk"), Hyper-V ("vhd"), and raw device images that are universally supported. These are not installation images, but rather the preconfigured ("already installed") instances, ready to run and perform post-installation tasks.
 * Virtual Machine images available at Amazon's https://aws.amazon.com/marketplace/pp/B07L6QV354[AWS Marketplace], https://azuremarketplace.microsoft.com/en-us/marketplace/apps?search=freebsd&page=1[Microsoft Azure Marketplace], and https://console.cloud.google.com/marketplace/details/freebsd-cloud/freebsd-12[Google Cloud Platform], to run on their respective hosting services. For more information on deploying FreeBSD on Azure please consult the relevant chapter in the https://docs.microsoft.com/en-us/azure/virtual-machines/linux/freebsd-intro-on-azure[Azure Documentation].
 * SD card images, for embedded systems such as Raspberry Pi or BeagleBone Black. These can be downloaded from the https://www.freebsd.org/where/[Download FreeBSD] page. These files must be uncompressed and written as a raw image to an SD card, from which the board will then boot.
 * Installation images, to install FreeBSD on a hard drive for the usual desktop, laptop, or server systems.
 
 The rest of this chapter describes the fourth case, explaining how to install FreeBSD using the text-based installation program named bsdinstall.
 
 In general, the installation instructions in this chapter are written for the i386(TM) and AMD64 architectures.
 Where applicable, instructions specific to other platforms will be listed.
 There may be minor differences between the installer and what is shown here, so use this chapter as a general guide rather than as a set of literal instructions.
 
 [NOTE]
 ====
 Users who prefer to install FreeBSD using a graphical installer may be interested in https://ghostbsd.org[GhostBSD], https://www.midnightbsd.org[MidnightBSD] or https://nomadbsd.org[NomadBSD].
 ====
 
 After reading this chapter, you will know:
 
 * The minimum hardware requirements and FreeBSD supported architectures.
 * How to create the FreeBSD installation media.
 * How to start bsdinstall.
 * The questions bsdinstall will ask, what they mean, and how to answer them.
 * How to troubleshoot a failed installation.
 * How to access a live version of FreeBSD before committing to an installation.
 
 Before reading this chapter, you should:
 
 * Read the supported hardware list that shipped with the version of FreeBSD to be installed and verify that the system's hardware is supported.
 
 [[bsdinstall-hardware]]
 == Minimum Hardware Requirements
 
 The hardware requirements to install FreeBSD vary by architecture.
 Hardware architectures and devices supported by a FreeBSD release are listed on the link:https://www.FreeBSD.org/releases/[FreeBSD Release Information] page.
 The link:https://www.FreeBSD.org/where/[FreeBSD download page] also has recommendations for choosing the correct image for different architectures.
 
 A FreeBSD installation requires a minimum of 96 MB of RAM and 1.5 GB of free hard drive space.
 However, such small amounts of memory and disk space are really only suitable for custom applications like embedded appliances.
 General-purpose desktop systems need more resources.
 2-4 GB RAM and at least 8 GB hard drive space is a good starting point.
 
 These are the processor requirements for each architecture:
 
 amd64::
 This is the most common desktop and laptop processor type, used in most modern systems.
 Intel(R) calls it Intel64.
 Other manufacturers sometimes call it x86-64.
 +
 Examples of amd64 compatible processors include: AMD Athlon(TM)64, AMD Opteron(TM), multi-core Intel(R) Xeon(TM), and Intel(R) Core(TM) 2 and later processors.
 
 i386::
 Older desktops and laptops often use this 32-bit, x86 architecture.
 +
 Almost all i386-compatible processors with a floating point unit are supported.
 All Intel(R) processors 486 or higher are supported.
 However, binaries released by the project are compiled for the 686 processor, so a special build will be needed for 486 and 586 systems.
 +
 FreeBSD will take advantage of Physical Address Extensions (PAE) support on CPUs with this feature.
 A kernel with the PAE feature enabled will detect memory above 4 GB and allow it to be used by the system.
 However, using PAE places constraints on device drivers and other features of FreeBSD.
 
 arm64::
 Most embedded boards are 64-bit ARM computers.
 A number of arm64 servers are supported.
 
 arm::
 Older armv7 boards are supported.
 
 powerpc::
 All New World ROM Apple(R) Mac(R) systems with built-in USB are supported.
 SMP is supported on machines with multiple CPUs.
 +
 A 32-bit kernel can only use the first 2 GB of RAM.
 
 [[bsdinstall-pre]]
 == Pre-Installation Tasks
 
 Once it has been determined that the system meets the minimum hardware requirements for installing FreeBSD, the installation file should be downloaded and the installation media prepared.
 Before doing this, check that the system is ready for an installation by verifying the items in this checklist:
 
 [.procedure]
 . *Back Up Important Data*
-+ 
++
 Before installing any operating system, _always_ backup all important data first.
 Do not store the backup on the system being installed.
 Instead, save the data to a removable disk such as a USB drive, another system on the network, or an online backup service.
 Test the backup before starting the installation to make sure it contains all of the needed files.
 Once the installer formats the system's disk, all data stored on that disk will be lost.
 . *Decide Where to Install FreeBSD*
-+ 
++
 If FreeBSD will be the only operating system installed, this step can be skipped.
 But if FreeBSD will share the disk with another operating system, decide which disk or partition will be used for FreeBSD.
-+ 
++
 In the i386 and amd64 architectures, disks can be divided into multiple partitions using one of two partitioning schemes.
 A traditional _Master Boot Record_ (MBR) holds a partition table defining up to four _primary partitions_.
 For historical reasons, FreeBSD calls these primary partition _slices_.
 One of these primary partitions can be made into an _extended partition_ containing multiple _logical partitions_.
 The _GUID Partition Table_ (GPT) is a newer and simpler method of partitioning a disk.
 Common GPT implementations allow up to 128 partitions per disk, eliminating the need for logical partitions.
-+ 
++
 The FreeBSD boot loader requires either a primary or GPT partition.
 If all of the primary or GPT partitions are already in use, one must be freed for FreeBSD.
 To create a partition without deleting existing data, use a partition resizing tool to shrink an existing partition and create a new partition using the freed space.
-+ 
++
 A variety of free and commercial partition resizing tools are listed at http://en.wikipedia.org/wiki/List_of_disk_partitioning_software[http://en.wikipedia.org/wiki/List_of_disk_partitioning_software].
 GParted Live (http://gparted.sourceforge.net/livecd.php[http://gparted.sourceforge.net/livecd.php]) is a free live CD which includes the GParted partition editor.
 GParted is also included with many other Linux live CD distributions.
 +
 [WARNING]
 ====
 When used properly, disk shrinking utilities can safely create space for creating a new partition.
 Since the possibility of selecting the wrong partition exists, always backup any important data and verify the integrity of the backup before modifying disk partitions.
 ====
-+ 
++
 Disk partitions containing different operating systems make it possible to install multiple operating systems on one computer.
 An alternative is to use virtualization (crossref:virtualization[virtualization,Virtualization]) which allows multiple operating systems to run at the same time without modifying any disk partitions.
 . *Collect Network Information*
-+ 
++
 Some FreeBSD installation methods require a network connection in order to download the installation files.
 After any installation, the installer will offer to setup the system's network interfaces.
-+ 
++
 If the network has a DHCP server, it can be used to provide automatic network configuration.
 If DHCP is not available, the following network information for the system must be obtained from the local network administrator or Internet service provider:
 +
 [[bsdinstall-collect-network-information]]
 Required Network Information
 
 .. IP address
 .. Subnet mask
 .. IP address of default gateway
 .. Domain name of the network
 .. IP addresses of the network's DNS servers
 
 . *Check for FreeBSD Errata*
 +
 Although the FreeBSD Project strives to ensure that each release of FreeBSD is as stable as possible, bugs occasionally creep into the process.
 On very rare occasions those bugs affect the installation process.
 As these problems are discovered and fixed, they are noted in the FreeBSD Errata (link:https://www.FreeBSD.org/releases/{rel121-current}R/errata/[https://www.freebsd.org/releases/{rel121-current}R/errata/]) on the FreeBSD web site.
 Check the errata before installing to make sure that there are no problems that might affect the installation.
-+ 
++
 Information and errata for all the releases can be found on the release information section of the FreeBSD web site (link:https://www.FreeBSD.org/releases/[https://www.freebsd.org/releases/]).
 
 [[bsdinstall-installation-media]]
 === Prepare the Installation Media
 
 The FreeBSD installer is not an application that can be run from within another operating system.
 Instead, download a FreeBSD installation file, burn it to the media associated with its file type and size (CD, DVD, or USB), and boot the system to install from the inserted media.
 
 FreeBSD installation files are available at link:https://www.FreeBSD.org/where/[www.freebsd.org/where/].
 Each installation file's name includes the release version of FreeBSD, the architecture, and the type of file.
 For example, to install FreeBSD 12.1 on an amd64 system from a DVD, download [.filename]#FreeBSD-12.1-RELEASE-amd64-dvd1.iso#, burn this file to a DVD, and boot the system with the DVD inserted.
 
 Installation files are available in several formats.
 The formats vary depending on computer architecture and media type.
 
 [[bsdinstall-installation-media-uefi]]
 Additional installation files are included for computers that boot with UEFI (Unified Extensible Firmware Interface).
 The names of these files include the string [.filename]#uefi#.
 
 File types:
 
 * `-bootonly.iso`: This is the smallest installation file as it only contains the installer. A working Internet connection is required during installation as the installer will download the files it needs to complete the FreeBSD installation. This file should be burned to a CD using a CD burning application.
 * `-disc1.iso`: This file contains all of the files needed to install FreeBSD, its source, and the Ports Collection. It should be burned to a CD using a CD burning application.
 * `-dvd1.iso`: This file contains all of the files needed to install FreeBSD, its source, and the Ports Collection. It also contains a set of popular binary packages for installing a window manager and some applications so that a complete system can be installed from media without requiring a connection to the Internet. This file should be burned to a DVD using a DVD burning application.
 * `-memstick.img`: This file contains all of the files needed to install FreeBSD, its source, and the Ports Collection. It should be burned to a USB stick using the instructions below.
 * `-mini-memstick.img`: Like `-bootonly.iso`, does not include installation files, but downloads them as needed. A working internet connection is required during installation. Write this file to a USB stick as shown in <<bsdinstall-usb>>.
 
 After downloading the image file, download [.filename]#CHECKSUM.SHA256# from the same directory.
 Calculate a _checksum_ for the image file.
 FreeBSD provides man:sha256[1] for this, used as `sha256 _imagefilename_`.
 Other operating systems have similar programs.
 
 Compare the calculated checksum with the one shown in [.filename]#CHECKSUM.SHA256#.
 The checksums must match exactly.
 If the checksums do not match, the image file is corrupt and must be downloaded again.
 
 [[bsdinstall-usb]]
 ==== Writing an Image File to USB
 
 The [.filename]#\*.img# file is an _image_ of the complete contents of a memory stick.
 It _cannot_ be copied to the target device as a file.
 Several applications are available for writing the [.filename]#*.img# to a USB stick.
 This section describes two of these utilities.
 
 [IMPORTANT]
 ====
 Before proceeding, back up any important data on the USB stick.
 This procedure will erase the existing data on the stick.
 ====
 
 [[bsdinstall-usb-dd]]
 [.procedure]
 ****
 *Procedure. Using `dd` to Write the Image* +
 
 [WARNING]
 ====
 This example uses [.filename]#/dev/da0# as the target device where the image will be written.
 Be _very careful_ that the correct device is used as this command will destroy the existing data on the specified target device.
 ====
 
 . The command-line utility is available on BSD, Linux(R), and Mac OS(R) systems. To burn the image using `dd`, insert the USB stick and determine its device name. Then, specify the name of the downloaded installation file and the device name for the USB stick. This example burns the amd64 installation image to the first USB device on an existing FreeBSD system.
 +
 [source,shell]
 ....
 # dd if=FreeBSD-12.1-RELEASE-amd64-memstick.img of=/dev/da0 bs=1M conv=sync
 ....
 +
 If this command fails, verify that the USB stick is not mounted and that the device name is for the disk, not a partition.
 Some operating systems might require this command to be run with man:sudo[8].
 The man:dd[1] syntax varies slightly across different platforms; for example, Mac OS(R) requires a lower-case `bs=1m`.
 Systems like Linux(R) might buffer writes.
 To force all writes to complete, use man:sync[8].
 ****
 
 [.procedure]
 ****
 *Procedure. Using Windows(R) to Write the Image* +
 
 [WARNING]
 ====
 
 Be sure to give the correct drive letter as the existing data on the specified drive will be overwritten and destroyed.
 ====
 . *Obtaining Image Writer for Windows(R)*
 +
 Image Writer for Windows(R) is a free application that can correctly write an image file to a memory stick.
 Download it from https://sourceforge.net/projects/win32diskimager/[https://sourceforge.net/projects/win32diskimager/] and extract it into a folder.
 
 . *Writing the Image with Image Writer*
 +
 Double-click the Win32DiskImager icon to start the program.
 Verify that the drive letter shown under `Device` is the drive with the memory stick.
 Click the folder icon and select the image to be written to the memory stick.
 Click btn:[Save] to accept the image file name.
 Verify that everything is correct, and that no folders on the memory stick are open in other windows.
 When everything is ready, click btn:[Write] to write the image file to the memory stick.
 ****
 
 You are now ready to start installing FreeBSD.
 
 [[bsdinstall-start]]
 == Starting the Installation
 
 [IMPORTANT]
 ====
 By default, the installation will not make any changes to the disk(s) before the following message:
 
 [.programlisting]
 ....
 Your changes will now be written to disk. If you
 have chosen to overwrite existing data, it will
 be PERMANENTLY ERASED. Are you sure you want to
 commit your changes?
 ....
 
 The install can be exited at any time prior to this warning.
 If there is a concern that something is incorrectly configured, just turn the computer off before this point and no changes will be made to the system's disks.
 ====
 
 This section describes how to boot the system from the installation media which was prepared using the instructions in <<bsdinstall-installation-media>>.
 When using a bootable USB stick, plug in the USB stick before turning on the computer.
 When booting from CD or DVD, turn on the computer and insert the media at the first opportunity.
 How to configure the system to boot from the inserted media depends upon the architecture.
 
 [[bsdinstall-starting-i386]]
 === Booting on i386(TM) and amd64
 
 These architectures provide a BIOS menu for selecting the boot device.
 Depending upon the installation media being used, select the CD/DVD or USB device as the first boot device.
 Most systems also provide a key for selecting the boot device during startup without having to enter the BIOS.
 Typically, the key is either kbd:[F10], kbd:[F11], kbd:[F12], or kbd:[Escape].
 
 If the computer loads the existing operating system instead of the FreeBSD installer, then either:
 
 . The installation media was not inserted early enough in the boot process. Leave the media inserted and try restarting the computer.
 . The BIOS changes were incorrect or not saved. Double-check that the right boot device is selected as the first boot device.
 . This system is too old to support booting from the chosen media. In this case, the Plop Boot Manager (http://www.plop.at/en/bootmanagers.html[]) can be used to boot the system from the selected media.
 
 === Booting on PowerPC(R)
 
 On most machines, holding kbd:[C] on the keyboard during boot will boot from the CD.
 Otherwise, hold kbd:[Command+Option+O+F], or kbd:[Windows+Alt+O+F] on non-Apple(R) keyboards.
 At the `0 >` prompt, enter
 
 [source,shell]
 ....
  boot cd:,\ppc\loader cd:0
 ....
 
 [[bsdinstall-view-probe]]
 === FreeBSD Boot Menu
 
 Once the system boots from the installation media, a menu similar to the following will be displayed:
 
 [[bsdinstall-newboot-loader-menu]]
 .FreeBSD Boot Loader Menu
 image::bsdinstall-newboot-loader-menu.png[]
 
 By default, the menu will wait ten seconds for user input before booting into the FreeBSD installer or, if FreeBSD is already installed, before booting into FreeBSD.
 To pause the boot timer in order to review the selections, press kbd:[Space].
 To select an option, press its highlighted number, character, or key.
 The following options are available.
 
 * `Boot Multi User`: This will continue the FreeBSD boot process. If the boot timer has been paused, press kbd:[1], upper- or lower-case kbd:[B], or kbd:[Enter].
 * `Boot Single User`: This mode can be used to fix an existing FreeBSD installation as described in crossref:boot[boot-singleuser,“Single-User Mode”]. Press kbd:[2] or the upper- or lower-case kbd:[S] to enter this mode.
 * `Escape to loader prompt`: This will boot the system into a repair prompt that contains a limited number of low-level commands. This prompt is described in crossref:boot[boot-loader,“Stage Three”]. Press kbd:[3] or kbd:[Esc] to boot into this prompt.
 * `Reboot`: Reboots the system.
 * `Kernel`: Loads a different kernel.
 * `Configure Boot Options`: Opens the menu shown in, and described under, <<bsdinstall-boot-options-menu>>.
 
 [[bsdinstall-boot-options-menu]]
 .FreeBSD Boot Options Menu
 image::bsdinstall-boot-options-menu.png[]
 
 The boot options menu is divided into two sections.
 The first section can be used to either return to the main boot menu or to reset any toggled options back to their defaults.
 
 The next section is used to toggle the available options to `On` or `Off` by pressing the option's highlighted number or character.
 The system will always boot using the settings for these options until they are modified.
 Several options can be toggled using this menu:
 
 * `ACPI Support`: If the system hangs during boot, try toggling this option to `Off`.
 * `Safe Mode`: If the system still hangs during boot even with `ACPI Support` set to `Off`, try setting this option to `On`.
 * `Single User`: Toggle this option to `On` to fix an existing FreeBSD installation as described in crossref:boot[boot-singleuser,“Single-User Mode”]. Once the problem is fixed, set it back to `Off`.
 * `Verbose`: Toggle this option to `On` to see more detailed messages during the boot process. This can be useful when troubleshooting a piece of hardware.
 
 After making the needed selections, press kbd:[1] or kbd:[Backspace] to return to the main boot menu, then press kbd:[Enter] to continue booting into FreeBSD.
 A series of boot messages will appear as FreeBSD carries out its hardware device probes and loads the installation program.
 Once the boot is complete, the welcome menu shown in <<bsdinstall-choose-mode>> will be displayed.
 
 [[bsdinstall-choose-mode]]
 .Welcome Menu
 image::bsdinstall-choose-mode.png[]
 
 Press kbd:[Enter] to select the default of btn:[Install] to enter the installer.
 The rest of this chapter describes how to use this installer.
 Otherwise, use the right or left arrows or the colorized letter to select the desired menu item.
 The btn:[Shell] can be used to access a FreeBSD shell in order to use command line utilities to prepare the disks before installation.
 The btn:[Live CD] option can be used to try out FreeBSD before installing it.
 The live version is described in <<using-live-cd>>.
 
 [TIP]
 ====
 To review the boot messages, including the hardware device probe, press the upper- or lower-case kbd:[S] and then kbd:[Enter] to access a shell.
 At the shell prompt, type `more /var/run/dmesg.boot` and use the space bar to scroll through the messages.
 When finished, type `exit` to return to the welcome menu.
 ====
 
 [[using-bsdinstall]]
 == Using bsdinstall
 
 This section shows the order of the bsdinstall menus and the type of information that will be asked before the system is installed.
 Use the arrow keys to highlight a menu option, then kbd:[Space] to select or deselect that menu item.
 When finished, press kbd:[Enter] to save the selection and move onto the next screen.
 
 [[bsdinstall-keymap]]
 === Selecting the Keymap Menu
 
 Before starting the process, bsdinstall will load the keymap files as show in <<bsdinstall-keymap-loading>>.
 
 [[bsdinstall-keymap-loading]]
 .Keymap Loading
 image::bsdinstall-keymap-loading.png[]
 
 After the keymaps have been loaded bsdinstall displays the menu shown in <<bsdinstall-keymap-10>>.
 Use the up and down arrows to select the keymap that most closely represents the mapping of the keyboard attached to the system.
 Press kbd:[Enter] to save the selection.
 
 [[bsdinstall-keymap-10]]
 .Keymap Selection Menu
 image::bsdinstall-keymap-10.png[]
 
 [NOTE]
 ====
 Pressing kbd:[Esc] will exit this menu and use the default keymap.
 If the choice of keymap is not clear, [.guimenuitem]#United States of America ISO-8859-1# is also a safe option.
 ====
 
 In addition, when selecting a different keymap, the user can try the keymap and ensure it is correct before proceeding as shown in <<bsdinstall-keymap-testing>>.
 
 [[bsdinstall-keymap-testing]]
 .Keymap Testing Menu
 image::bsdinstall-keymap-testing.png[]
 
 [[bsdinstall-hostname]]
 === Setting the Hostname
 
 The next bsdinstall menu is used to set the hostname for the newly installed system.
 
 [[bsdinstall-config-hostname]]
 .Setting the Hostname
 image::bsdinstall-config-hostname.png[]
 
 Type in a hostname that is unique for the network.
 It should be a fully-qualified hostname, such as `machine3.example.com`.
 
 [[bsdinstall-components]]
 === Selecting Components to Install
 
 Next, bsdinstall will prompt to select optional components to install.
 
 [[bsdinstall-config-components]]
 .Selecting Components to Install
 image::bsdinstall-config-components.png[]
 
 Deciding which components to install will depend largely on the intended use of the system and the amount of disk space available.
 The FreeBSD kernel and userland, collectively known as the _base system_, are always installed.
 Depending on the architecture, some of these components may not appear:
 
 * `base-dbg` - Base tools like cat, ls among many others with debug symbols activated.
 * `kernel-dbg` - Kernel and modules with debug symbols activated.
 * `lib32-dbg` - Compatibility libraries for running 32-bit applications on a 64-bit version of FreeBSD with debug symbols activated.
 * `lib32` - Compatibility libraries for running 32-bit applications on a 64-bit version of FreeBSD.
 * `ports` - The FreeBSD Ports Collection is a collection of files which automates the downloading, compiling and installation of third-party software packages. crossref:ports[ports,Installing Applications: Packages and Ports] discusses how to use the Ports Collection.
 +
 [WARNING]
 ====
 The installation program does not check for adequate disk space.
 Select this option only if sufficient hard disk space is available.
 The FreeBSD Ports Collection takes up about {ports-size} of disk space.
 ====
 
 * `src` - The complete FreeBSD source code for both the kernel and the userland. Although not required for the majority of applications, it may be required to build device drivers, kernel modules, or some applications from the Ports Collection. It is also used for developing FreeBSD itself. The full source tree requires 1 GB of disk space and recompiling the entire FreeBSD system requires an additional 5 GB of space.
 * `tests` - FreeBSD Test Suite.
 
 [[bsdinstall-netinstall]]
 === Installing from the Network
 
 The menu shown in <<bsdinstall-netinstall-notify>> only appears when installing from a [.filename]#-bootonly.iso# or [.filename]#-mini-memstick.img# as this installation media does not hold copies of the installation files.
 Since the installation files must be retrieved over a network connection, this menu indicates that the network interface must be configured first.
 If this menu is shown in any step of the process remember to follow the instructions in <<bsdinstall-config-network-dev>>.
 
 [[bsdinstall-netinstall-notify]]
 .Installing from the Network
 image::bsdinstall-netinstall-files.png[]
 
 [[bsdinstall-partitioning]]
 == Allocating Disk Space
 
 The next menu is used to determine the method for allocating disk space.
 
 [[bsdinstall-zfs-partmenu]]
 .Partitioning Choices
 image::bsdinstall-zfs-partmenu.png[]
 
 bsdinstall gives the user four methods for allocating disk space:
 
 * `Auto (UFS)` partitioning automatically sets up the disk partitions using the `UFS` file system.
 * `Manual` partitioning allows advanced users to create customized partitions from menu options.
 * `Shell` opens a shell prompt where advanced users can create customized partitions using command-line utilities like man:gpart[8], man:fdisk[8], and man:bsdlabel[8].
 * `Auto (ZFS)` partitioning creates a root-on-ZFS system with optional GELI encryption support for _boot environments_.
 
 This section describes what to consider when laying out the disk partitions.
 It then demonstrates how to use the different partitioning methods.
 
 [[configtuning-initial]]
 === Designing the Partition Layout
 
 When laying out file systems, remember that hard drives transfer data faster from the outer tracks to the inner.
 Thus, smaller and heavier-accessed file systems should be closer to the outside of the drive, while larger partitions like [.filename]#/usr# should be placed toward the inner parts of the disk.
 It is a good idea to create partitions in an order similar to: [.filename]#/#, swap, [.filename]#/var#, and [.filename]#/usr#.
 
 The size of the [.filename]#/var# partition reflects the intended machine's usage.
 This partition is used to hold mailboxes, log files, and printer spools.
 Mailboxes and log files can grow to unexpected sizes depending on the number of users and how long log files are kept.
 On average, most users rarely need more than about a gigabyte of free disk space in [.filename]#/var#.
 
 [NOTE]
 ====
 Sometimes, a lot of disk space is required in [.filename]#/var/tmp#.
 When new software is installed, the packaging tools extract a temporary copy of the packages under [.filename]#/var/tmp#.
 Large software packages, like Firefox or LibreOffice may be tricky to install if there is not enough disk space under [.filename]#/var/tmp#.
 ====
 
 The [.filename]#/usr# partition holds many of the files which support the system, including the FreeBSD Ports Collection and system source code.
 At least 2 gigabytes of space is recommended for this partition.
 
 When selecting partition sizes, keep the space requirements in mind.
 Running out of space in one partition while barely using another can be a hassle.
 
 As a rule of thumb, the swap partition should be about double the size of physical memory (RAM).
 Systems with minimal RAM may perform better with more swap.
 Configuring too little swap can lead to inefficiencies in the VM page scanning code and might create issues later if more memory is added.
 
 On larger systems with multiple SCSI disks or multiple IDE disks operating on different controllers, it is recommended that swap be configured on each drive, up to four drives.
 The swap partitions should be approximately the same size.
 The kernel can handle arbitrary sizes but internal data structures scale to 4 times the largest swap partition.
 Keeping the swap partitions near the same size will allow the kernel to optimally stripe swap space across disks.
 Large swap sizes are fine, even if swap is not used much.
 It might be easier to recover from a runaway program before being forced to reboot.
 
 By properly partitioning a system, fragmentation introduced in the smaller write heavy partitions will not bleed over into the mostly read partitions. 
 Keeping the write loaded partitions closer to the disk's edge will increase I/O performance in the partitions where it occurs the most.
 While I/O performance in the larger partitions may be needed, shifting them more toward the edge of the disk will not lead to a significant performance improvement over moving [.filename]#/var# to the edge.
 
 [[bsdinstall-part-guided]]
 === Guided Partitioning Using UFS
 
 When this method is selected, a menu will display the available disk(s).
 If multiple disks are connected, choose the one where FreeBSD is to be installed.
 
 [[bsdinstall-part-guided-disk]]
 .Selecting from Multiple Disks
 image::bsdinstall-part-guided-disk.png[]
 
 Once the disk is selected, the next menu prompts to install to either the entire disk or to create a partition using free space.
 If btn:[Entire Disk] is chosen, a general partition layout filling the whole disk is automatically created.
 Selecting btn:[Partition] creates a partition layout from the unused space on the disk.
 
 [[bsdinstall-part-entire-part]]
 .Selecting Entire Disk or Partition
 image::bsdinstall-part-entire-part.png[]
 
 After btn:[Entire Disk] is chosen bsdinstall displays a dialog indicating that the disk will be erased.
 
 [[bsdinstall-ufs-warning]]
 .Confirmation
 image::bsdinstall-ufs-warning.png[]
 
 The next menu shows a list with the partition schemes types.
 GPT is usually the most appropriate choice for amd64 computers.
 Older computers that are not compatible with GPT should use MBR.
 The other partition schemes are generally used for uncommon or older computers.
 More information is available in <<partition-schemes>>.
 
 [[bsdinstall-ufs-scheme]]
 .Select Partition Scheme
 image::bsdinstall-part-manual-partscheme.png[]
 
 After the partition layout has been created, review it to ensure it meets the needs of the installation.
 Selecting btn:[Revert] will reset the partitions to their original values and pressing btn:[Auto] will recreate the automatic FreeBSD partitions.
 Partitions can also be manually created, modified, or deleted.
 When the partitioning is correct, select btn:[Finish] to continue with the installation.
 
 [[bsdinstall-part-review]]
 .Review Created Partitions
 image::bsdinstall-part-review.png[]
 
 Once the disks are configured, the next menu provides the last chance to make changes before the selected drives are formatted.
 If changes need to be made, select btn:[Back] to return to the main partitioning menu.
 btn:[Revert & Exit] exits the installer without making any changes to the drive.
 Select btn:[Commit] to start the installation process.
 
 [[bsdinstall-ufs-final-confirmation]]
 .Final Confirmation
 image::bsdinstall-final-confirmation.png[]
 
 To continue with the installation process go to <<bsdinstall-fetching-distribution>>.
 
 [[bsdinstall-part-manual]]
 === Manual Partitioning
 
 Selecting this method opens the partition editor:
 
 [[bsdinstall-part-manual-create]]
 .Manually Create Partitions
 image::bsdinstall-part-manual-create.png[]
 
 Highlight the installation drive ([.filename]#ada0# in this example) and select btn:[Create] to display a menu of available partition schemes:
 
 [[bsdinstall-part-manual-partscheme]]
 .Manually Create Partitions
 image::bsdinstall-part-manual-partscheme.png[]
 
 GPT is usually the most appropriate choice for amd64 computers.
 Older computers that are not compatible with GPT should use MBR.
 The other partition schemes are generally used for uncommon or older computers.
 
 [[partition-schemes]]
 .Partitioning Schemes
 [cols="1,1", frame="none", options="header"]
 |===
 <| Abbreviation
 <| Description
 
 |APM
 |Apple Partition Map, used by PowerPC(R).
 
 |BSD
 |BSD label without an MBR, sometimes called _dangerously dedicated mode_ as non-BSD disk utilities may not recognize it.
 
 |GPT
 |GUID Partition Table (http://en.wikipedia.org/wiki/GUID_Partition_Table[http://en.wikipedia.org/wiki/GUID_Partition_Table]).
 
 |MBR
 |Master Boot Record (http://en.wikipedia.org/wiki/Master_boot_record[http://en.wikipedia.org/wiki/Master_boot_record]).
 |===
 
 After the partitioning scheme has been selected and created, select btn:[Create] again to create the partitions.
 The kbd:[Tab] key is used to move the cursor between fields.
 
 [[bsdinstall-part-manual-addpart]]
 .Manually Create Partitions
 image::bsdinstall-part-manual-addpart.png[]
 
 A standard FreeBSD GPT installation uses at least three partitions:
 
 * `freebsd-boot` - Holds the FreeBSD boot code.
 * `freebsd-ufs` - A FreeBSD UFS file system.
 * `freebsd-zfs` - A FreeBSD ZFS file system. More information about ZFS is available in crossref:zfs[zfs,The Z File System (ZFS)].
 * `freebsd-swap` - FreeBSD swap space.
 
 Refer to man:gpart[8] for descriptions of the available GPT partition types.
 
 Multiple file system partitions can be created and some people prefer a traditional layout with separate partitions for [.filename]#/#, [.filename]#/var#, [.filename]#/tmp#, and [.filename]#/usr#.
 See <<bsdinstall-part-manual-splitfs>> for an example.
 
 The `Size` may be entered with common abbreviations: _K_ for kilobytes, _M_ for megabytes, or _G_ for gigabytes.
 
 [TIP]
 ====
 Proper sector alignment provides the best performance, and making partition sizes even multiples of 4K bytes helps to ensure alignment on drives with either 512-byte or 4K-byte sectors.
 Generally, using partition sizes that are even multiples of 1M or 1G is the easiest way to make sure every partition starts at an even multiple of 4K.
 There is one exception: the _freebsd-boot_ partition should be no larger than 512K due to current boot code limitations.
 ====
 
 A `Mountpoint` is needed if the partition will contain a file system.
 If only a single UFS partition will be created, the mountpoint should be [.filename]#/#.
 
 The `Label` is a name by which the partition will be known.
 Drive names or numbers can change if the drive is connected to a different controller or port, but the partition label does not change.
 Referring to labels instead of drive names and partition numbers in files like [.filename]#/etc/fstab# makes the system more tolerant to hardware changes.
 GPT labels appear in [.filename]#/dev/gpt/# when a disk is attached.
 Other partitioning schemes have different label capabilities and their labels appear in different directories in [.filename]#/dev/#.
 
 [TIP]
 ====
 Use a unique label on every partition to avoid conflicts from identical labels.
 A few letters from the computer's name, use, or location can be added to the label.
 For instance, use `labroot` or `rootfslab` for the UFS root partition on the computer named `lab`.
 ====
 
 [[bsdinstall-part-manual-splitfs]]
 .Creating Traditional Split File System Partitions
 [example]
 ====
 For a traditional partition layout where the [.filename]#/#, [.filename]#/var#, [.filename]#/tmp#, and [.filename]#/usr# directories are separate file systems on their own partitions, create a GPT partitioning scheme, then create the partitions as shown.
 Partition sizes shown are typical for a 20G target disk.
 If more space is available on the target disk, larger swap or [.filename]#/var# partitions may be useful.
 Labels shown here are prefixed with `ex` for "example", but readers should use other unique label values as described above.
 
 By default, FreeBSD's [.filename]#gptboot# expects the first UFS partition to be the [.filename]#/# partition.
 
 [.informaltable]
 [cols="1,1,1,1", frame="none", options="header"]
 |===
 | Partition Type
 | Size
 | Mountpoint
 | Label
 
 |`freebsd-boot`
 |`512K`
 |
 |
 
 |`freebsd-ufs`
 |`2G`
 |[.filename]#/#
 |`exrootfs`
 
 |`freebsd-swap`
 |`4G`
 |
 |`exswap`
 
 |`freebsd-ufs`
 |`2G`
 |[.filename]#/var#
 |`exvarfs`
 
 |`freebsd-ufs`
 |`1G`
 |[.filename]#/tmp#
 |`extmpfs`
 
 |`freebsd-ufs`
 |accept the default (remainder of the disk)
 |[.filename]#/usr#
 |`exusrfs`
 |===
 ====
 
 After the custom partitions have been created, select btn:[Finish] to continue with the installation and go to <<bsdinstall-fetching-distribution>>.
 
 [[bsdinstall-part-zfs]]
 === Guided Partitioning Using Root-on-ZFS
 
 This partitioning mode only works with whole disks and will erase the contents of the entire disk.
 The main ZFS configuration menu offers a number of options to control the creation of the pool.
 
 [[bsdinstall-zfs-menu]]
 .ZFS Partitioning Menu
 image::bsdinstall-zfs-menu.png[]
 
 Here is a summary of the options which can be used in this menu:
 
 * `Install` - Proceed with the installation with the selected options.
 * `Pool Type/Disks` - Allow to configure the `Pool Type` and the disk(s) that will constitute the pool. The automatic ZFS installer currently only supports the creation of a single top level vdev, except in stripe mode. To create more complex pools, use the instructions in <<bsdinstall-part-shell>> to create the pool.
 * `Rescan Devices` - Repopulate the list of available disks.
 * `Disk Info` - Disk Info menu can be used to inspect each disk, including its partition table and various other information such as the device model number and serial number, if available.
 * `Pool Name` - Establish the name of the pool. The default name is _zroot_.
 * `Force 4K Sectors?` - Force the use of 4K sectors. By default, the installer will automatically create partitions aligned to 4K boundaries and force ZFS to use 4K sectors. This is safe even with 512 byte sector disks, and has the added benefit of ensuring that pools created on 512 byte disks will be able to have 4K sector disks added in the future, either as additional storage space or as replacements for failed disks. Press the kbd:[Enter] key to chose to activate it or not.
 * `Encrypt Disks?` - Encrypting the disks allows the user to encrypt the disks using GELI. More information about disk encryption is available in crossref:disks[disks-encrypting-geli,“Disk Encryption with geli”]. Press the kbd:[Enter] key to chose activate it or not.
 * `Partition Scheme` - Allow to choose the partition scheme. GPT is the recommended option in most cases. Press the kbd:[Enter] key to chose between the different options.
 * `Swap Size` - Establish the amount of swap space.
 * `Mirror Swap?` - Allows the user to mirror the swap between the disks. Be aware, enabling mirror swap will break crash dumps. Press the kbd:[Enter] key to activate it or not.
 * `Encrypt Swap?` - Allow the user the possibility to encrypt the swap. Encrypts the swap with a temporary key each time that the system boots and discards it on reboot. Press the kbd:[Enter] key to chose activate it or not. More information about swap encryption in crossref:disks[swap-encrypting,“Encrypting Swap”].
 
 Select kbd:[T] to configure the `Pool Type` and the disk(s) that will constitute the pool.
 
 [[bsdinstall-zfs-vdev_type]]
 .ZFS Pool Type
 image::bsdinstall-zfs-vdev_type.png[]
 
 Here is a summary of the `Pool Type` which can be selected in this menu:
 
 * `stripe` - Striping provides maximum storage of all connected devices, but no redundancy. If just one disk fails the data on the pool is lost irrevocably.
 * `mirror` - Mirroring stores a complete copy of all data on every disk. Mirroring provides a good read performance because data is read from all disks in parallel. Write performance is slower as the data must be written to all disks in the pool. Allows all but one disk to fail. This option requires at least two disks.
 * `raid10` - Striped mirrors. Provides the best performance, but the least storage. This option needs at least an even number of disks and a minimum of four disks.
 * `raidz1` - Single Redundant RAID. Allow one disk to fail concurrently. This option needs at least three disks.
 * `raidz2` - Double Redundant RAID. Allows two disks to fail concurrently. This option needs at least four disks.
 * `raidz3` - Triple Redundant RAID. Allows three disks to fail concurrently. This option needs at least five disks.
 
 Once a `Pool Type` has been selected, a list of available disks is displayed, and the user is prompted to select one or more disks to make up the pool.
 The configuration is then validated, to ensure enough disks are selected.
 If not, select btn:[<Change Selection>] to return to the list of disks, or btn:[<Back>] to change the `Pool Type`.
 
 [[bsdinstall-zfs-disk_select]]
 .Disk Selection
 image::bsdinstall-zfs-disk_select.png[]
 
 [[bsdinstall-zfs-vdev_invalid]]
 .Invalid Selection
 image::bsdinstall-zfs-vdev_invalid.png[]
 
 If one or more disks are missing from the list, or if disks were attached after the installer was started, select btn:[- Rescan Devices] to repopulate the list of available disks.
 
 [[bsdinstall-zfs-rescan-devices]]
 .Rescan Devices
 image::bsdinstall-zfs-rescan-devices.png[]
 
 To avoid accidentally erasing the wrong disk, the btn:[- Disk Info] menu can be used to inspect each disk, including its partition table and various other information such as the device model number and serial number, if available.
 
 [[bsdinstall-zfs-disk_info]]
 .Analyzing a Disk
 image::bsdinstall-zfs-disk_info.png[]
 
 Select kbd:[N] to configure the `Pool Name`.
 Enter the desired name then select btn:[<OK>] to establish it or btn:[<Cancel>] to return to the main menu and leave the default name.
 
 [[bsdinstall-zfs-pool-name]]
 .Pool Name
 image::bsdinstall-zfs-pool-name.png[]
 
 Select kbd:[S] to set the amount of swap.
 Enter the desired amount of swap and then select btn:[<OK>] to establish it or btn:[<Cancel>] to return to the main menu and let the default amount.
 
 [[bsdinstall-zfs-swap-amount]]
 .Swap Amount
 image::bsdinstall-zfs-swap-amount.png[]
 
 Once all options have been set to the desired values, select the btn:[>>> Install] option at the top of the menu.
 The installer then offers a last chance to cancel before the contents of the selected drives are destroyed to create the ZFS pool.
 
 [[bsdinstall-zfs-warning]]
 .Last Chance
 image::bsdinstall-zfs-warning.png[]
 
 If GELI disk encryption was enabled, the installer will prompt twice for the passphrase to be used to encrypt the disks.
 And after that the initializing of the encryption begins.
 
 [[bsdinstall-zfs-geli_password]]
 .Disk Encryption Password
 image::bsdinstall-zfs-geli_password.png[]
 
 [[bsdinstall-zfs-init-encription]]
 .Initializing Encryption
 image::bsdinstall-zfs-init-encription.png[]
 
 The installation then proceeds normally.
 To continue with the installation go to <<bsdinstall-fetching-distribution>>.
 
 [[bsdinstall-part-shell]]
 === Shell Mode Partitioning
 
 When creating advanced installations, the bsdinstall partitioning menus may not provide the level of flexibility required.
 Advanced users can select the btn:[Shell] option from the partitioning menu in order to manually partition the drives, create the file system(s), populate [.filename]#/tmp/bsdinstall_etc/fstab#, and mount the file systems under [.filename]#/mnt#.
 Once this is done, type `exit` to return to bsdinstall and continue the installation.
 
 [[bsdinstall-fetching-distribution]]
 == Fetching Distribution Files
 
 Installation time will vary depending on the distributions chosen, installation media, and speed of the computer.
 A series of messages will indicate the progress.
 
 First, the installer formats the selected disk(s) and initializes the partitions.
 Next, in the case of a `bootonly media` or `mini memstick`, it downloads the selected components:
 
 [[bsdinstall-distfile-fetching]]
 .Fetching Distribution Files
 image::bsdinstall-distfile-fetching.png[]
 
 Next, the integrity of the distribution files is verified to ensure they have not been corrupted during download or misread from the installation media:
 
 [[bsdinstall-distfile-verify]]
 .Verifying Distribution Files
 image::bsdinstall-distfile-verifying.png[]
 
 Finally, the verified distribution files are extracted to the disk:
 
 [[bsdinstall-distfile-extract]]
 .Extracting Distribution Files
 image::bsdinstall-distfile-extracting.png[]
 
 Once all requested distribution files have been extracted, bsdinstall displays the first post-installation configuration screen.
 The available post-configuration options are described in the next section.
 
 [[bsdinstall-post]]
 == Accounts, Time Zone, Services and Hardening
 
 [[bsdinstall-post-root]]
 === Setting the `root` Password
 
 First, the `root` password must be set.
 While entering the password, the characters being typed are not displayed on the screen.
 After the password has been entered, it must be entered again.
 This helps prevent typing errors.
 
 [[bsdinstall-post-set-root-passwd]]
 .Setting the `root` Password
 image::bsdinstall-post-root-passwd.png[]
 
 [[bsdinstall-timezone]]
 === Setting the Time Zone
 
 The next series of menus are used to determine the correct local time by selecting the geographic region, country, and time zone.
 Setting the time zone allows the system to automatically correct for regional time changes, such as daylight savings time, and perform other time zone related functions properly.
 
 The example shown here is for a machine located in the mainland time zone of Spain, Europe.
 The selections will vary according to the geographical location.
 
 [[bsdinstall-timezone-region]]
 .Select a Region
 image::bsdinstall-timezone-region.png[]
 
 The appropriate region is selected using the arrow keys and then pressing kbd:[Enter].
 
 [[bsdinstall-timezone-country]]
 .Select a Country
 image::bsdinstall-timezone-country.png[]
 
 Select the appropriate country using the arrow keys and press kbd:[Enter].
 
 [[bsdinstall-timezone-zone]]
 .Select a Time Zone
 image::bsdinstall-timezone-zone.png[]
 
 The appropriate time zone is selected using the arrow keys and pressing kbd:[Enter].
 
 [[bsdinstall-timezone-confirmation]]
 .Confirm Time Zone
 image::bsdinstall-timezone-confirm.png[]
 
 Confirm the abbreviation for the time zone is correct.
 
 [[bsdinstall-timezone-date]]
 .Select Date
 image::bsdinstall-timezone-date.png[]
 
 The appropriate date is selected using the arrow keys and then pressing btn:[Set Date].
 Otherwise, the date selection can be skipped by pressing btn:[Skip].
 
 [[bsdinstall-timezone-time]]
 .Select Time
 image::bsdinstall-timezone-time.png[]
 
 The appropriate time is selected using the arrow keys and then pressing btn:[Set Time].
 Otherwise, the time selection can be skipped by pressing btn:[Skip].
 
 [[bsdinstall-sysconf]]
 === Enabling Services
 
 The next menu is used to configure which system services will be started whenever the system boots.
 All of these services are optional.
 Only start the services that are needed for the system to function.
 
 [[bsdinstall-config-serv]]
 .Selecting Additional Services to Enable
 image::bsdinstall-config-services.png[]
 
 Here is a summary of the services which can be enabled in this menu:
 
 * `local_unbound` - Enable the DNS local unbound. It is necessary to keep in mind that this is the unbound of the base system and is only meant for use as a local caching forwarding resolver. If the objective is to set up a resolver for the entire network install package:dns/unbound[].
 * `sshd` - The Secure Shell (SSH) daemon is used to remotely access a system over an encrypted connection. Only enable this service if the system should be available for remote logins.
 * `moused` - Enable this service if the mouse will be used from the command-line system console.
 * `ntpdate` - Enable the automatic clock synchronization at boot time. The functionality of this program is now available in the man:ntpd[8] daemon. After a suitable period of mourning, the man:ntpdate[8] utility will be retired.
 * `ntpd` - The Network Time Protocol (NTP) daemon for automatic clock synchronization. Enable this service if there is a Windows(R), Kerberos, or LDAP server on the network.
 * `powerd` - System power control utility for power control and energy saving.
 * `dumpdev` - Enabling crash dumps is useful in debugging issues with the system, so users are encouraged to enable crash dumps.
 
 [[bsdinstall-hardening]]
 === Enabling Hardening Security Options
 
 The next menu is used to configure which security options will be enabled.
 All of these options are optional.
 But their use is encouraged.
 
 [[bsdinstall-hardening-options]]
 .Selecting Hardening Security Options
 image::bsdinstall-hardening.png[]
 
 Here is a summary of the options which can be enabled in this menu:
 
 * `hide_uids` - Hide processes running as other users to prevent the unprivileged users to see other running processes in execution by other users (UID) preventing information leakage.
 * `hide_gids` - Hide processes running as other groups to prevent the unprivileged users to see other running processes in execution by other groups (GID) preventing information leakage.
 * `hide_jail` - Hide processes running in jails to prevent the unprivileged users to see processes running inside the jails.
 * `read_msgbuf` - Disabling reading kernel message buffer for unprivileged users prevent from using man:dmesg[8] to view messages from the kernel's log buffer.
 * `proc_debug` - Disabling process debugging facilities for unprivileged users disables a variety of unprivileged inter-process debugging services, including some procfs functionality, ptrace(), and ktrace(). Please note that this will also prevent debugging tools, for instance man:lldb[1], man:truss[1], man:procstat[1], as well as some built-in debugging facilities in certain scripting language like PHP, etc., from working for unprivileged users.
 * `random_pid` - Randomize the PID of newly created processes.
 * `clear_tmp` - Clean [.filename]#/tmp# when the system starts up.
 * `disable_syslogd` - Disable opening syslogd network socket. By default FreeBSD runs syslogd in a secure way with `-s`. That prevents the daemon from listening for incoming UDP requests at port 514. With this option enabled syslogd will run with the flag `-ss` which prevents syslogd from opening any port. To get more information consult man:syslogd[8].
 * `disable_sendmail` - Disable the sendmail mail transport agent.
 * `secure_console` - When this option is enabled, the prompt requests the `root` password when entering single-user mode.
 * `disable_ddtrace` - DTrace can run in a mode that will actually affect the running kernel. Destructive actions may not be used unless they have been explicitly enabled. To enable this option when using DTrace use `-w`. To get more information consult man:dtrace[1].
 
 [[bsdinstall-addusers]]
 === Add Users
 
 The next menu prompts to create at least one user account.
 It is recommended to login to the system using a user account rather than as `root`.
 When logged in as `root`, there are essentially no limits or protection on what can be done.
 Logging in as a normal user is safer and more secure.
 
 Select btn:[Yes] to add new users.
 
 [[bsdinstall-add-user1]]
 .Add User Accounts
 image::bsdinstall-adduser1.png[]
 
 Follow the prompts and input the requested information for the user account.
 The example shown in <<bsdinstall-add-user2>> creates the `asample` user account.
 
 [[bsdinstall-add-user2]]
 .Enter User Information
 image::bsdinstall-adduser2.png[]
 
 Here is a summary of the information to input:
 
 * `Username` - The name the user will enter to log in. A common convention is to use the first letter of the first name combined with the last name, as long as each username is unique for the system. The username is case sensitive and should not contain any spaces.
 * `Full name` - The user's full name. This can contain spaces and is used as a description for the user account.
 * `Uid` - User ID. Typically, this is left blank so the system will assign a value.
 * `Login group` - The user's group. Typically this is left blank to accept the default.
 * `Invite _user_ into other groups?` - Additional groups to which the user will be added as a member. If the user needs administrative access, type `wheel` here.
 * `Login class` - Typically left blank for the default.
 * `Shell` - Type in one of the listed values to set the interactive shell for the user. Refer to crossref:basics[shells,“Shells”] for more information about shells.
 * `Home directory` - The user's home directory. The default is usually correct.
 * `Home directory permissions` - Permissions on the user's home directory. The default is usually correct.
 * `Use password-based authentication?` - Typically `yes` so that the user is prompted to input their password at login.
 * `Use an empty password?` - Typically `no` as it is insecure to have a blank password.
 * `Use a random password?` - Typically `no` so that the user can set their own password in the next prompt.
 * `Enter password` - The password for this user. Characters typed will not show on the screen.
 * `Enter password again` - The password must be typed again for verification.
 * `Lock out the account after creation?` - Typically `no` so that the user can login.
 
 After entering everything, a summary is shown for review.
 If a mistake was made, enter `no` and try again.
 If everything is correct, enter `yes` to create the new user.
 
 [[bsdinstall-add-user3]]
 .Exit User and Group Management
 image::bsdinstall-adduser3.png[]
 
 If there are more users to add, answer the `Add another user?` question with `yes`.
 Enter `no` to finish adding users and continue the installation.
 
 For more information on adding users and user management, see crossref:basics[users-synopsis,“Users and Basic Account Management”].
 
 [[bsdinstall-final-conf]]
 === Final Configuration
 
 After everything has been installed and configured, a final chance is provided to modify settings.
 
 [[bsdinstall-final-config]]
 .Final Configuration
 image::bsdinstall-finalconfiguration.png[]
 
 Use this menu to make any changes or do any additional configuration before completing the installation.
 
 * `Add User` - Described in <<bsdinstall-addusers>>.
 * `Root Password` - Described in <<bsdinstall-post-root>>.
 * `Hostname` - Described in <<bsdinstall-hostname>>.
 * `Network` - Described in <<bsdinstall-config-network-dev>>.
 * `Services` - Described in <<bsdinstall-sysconf>>.
 * `System Hardening` - Described in <<bsdinstall-hardening>>.
 * `Time Zone` - Described in <<bsdinstall-timezone>>.
 * `Handbook` - Download and install the FreeBSD Handbook.
 
 After any final configuration is complete, select btn:[Exit].
 
 [[bsdinstall-final-modification-shell]]
 .Manual Configuration
 image::bsdinstall-final-modification-shell.png[]
 
 bsdinstall will prompt if there are any additional configuration that needs to be done before rebooting into the new system.
 Select btn:[Yes] to exit to a shell within the new system or btn:[No] to proceed to the last step of the installation.
 
 [[bsdinstall-final-main]]
 .Complete the Installation
 image::bsdinstall-mainexit.png[]
 
 If further configuration or special setup is needed, select btn:[Live CD] to boot the install media into Live CD mode.
 
 If the installation is complete, select btn:[Reboot] to reboot the computer and start the new FreeBSD system.
 Do not forget to remove the FreeBSD install media or the computer may boot from it again.
 
 As FreeBSD boots, informational messages are displayed.
 After the system finishes booting, a login prompt is displayed.
 At the `login:` prompt, enter the username added during the installation.
 Avoid logging in as `root`.
 Refer to crossref:basics[users-superuser,“The Superuser Account”] for instructions on how to become the superuser when administrative access is needed.
 
 The messages that appeared during boot can be reviewed by pressing kbd:[Scroll-Lock] to turn on the scroll-back buffer.
 The kbd:[PgUp], kbd:[PgDn], and arrow keys can be used to scroll back through the messages.
 When finished, press kbd:[Scroll-Lock] again to unlock the display and return to the console.
 To review these messages once the system has been up for some time, type `less /var/run/dmesg.boot` from a command prompt.
 Press kbd:[q] to return to the command line after viewing.
 
 If sshd was enabled in <<bsdinstall-config-serv>>, the first boot may be a bit slower as the system will generate the RSA and DSA keys.
 Subsequent boots will be faster.
 The fingerprints of the keys will be displayed, as seen in this example:
 
 [source,shell]
 ....
 Generating public/private rsa1 key pair.
 Your identification has been saved in /etc/ssh/ssh_host_key.
 Your public key has been saved in /etc/ssh/ssh_host_key.pub.
 The key fingerprint is:
 10:a0:f5:af:93:ae:a3:1a:b2:bb:3c:35:d9:5a:b3:f3 root@machine3.example.com
 The key's randomart image is:
 +--[RSA1 1024]----+
 |    o..          |
 |   o . .         |
 |  .   o          |
 |       o         |
 |    o   S        |
 |   + + o         |
 |o . + *          |
 |o+ ..+ .         |
 |==o..o+E         |
 +-----------------+
 Generating public/private dsa key pair.
 Your identification has been saved in /etc/ssh/ssh_host_dsa_key.
 Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub.
 The key fingerprint is:
 7e:1c:ce:dc:8a:3a:18:13:5b:34:b5:cf:d9:d1:47:b2 root@machine3.example.com
 The key's randomart image is:
 +--[ DSA 1024]----+
 |       ..     . .|
 |      o  .   . + |
 |     . ..   . E .|
 |    . .  o o . . |
 |     +  S = .    |
 |    +  . = o     |
 |     +  . * .    |
 |    . .  o .     |
 |      .o. .      |
 +-----------------+
 Starting sshd.
 ....
 
 Refer to crossref:security[openssh,"OpenSSH"] for more information about fingerprints and SSH.
 
 FreeBSD does not install a graphical environment by default.
 Refer to crossref:x11[x11,The X Window System] for more information about installing and configuring a graphical window manager.
 
 Proper shutdown of a FreeBSD computer helps protect data and hardware from damage.
 _Do not turn off the power before the system has been properly shut down!_ If the user is a member of the `wheel` group, become the superuser by typing `su` at the command line and entering the `root` password.
 Then, type `shutdown -p now` and the system will shut down cleanly, and if the hardware supports it, turn itself off.
 
 [[bsdinstall-network]]
 == Network Interfaces
 
 [[bsdinstall-config-network-dev]]
 === Configuring Network Interfaces
 
 Next, a list of the network interfaces found on the computer is shown.
 Select the interface to configure.
 
 [[bsdinstall-configure-net-interface]]
 .Choose a Network Interface
 image::bsdinstall-configure-network-interface.png[]
 
 If an Ethernet interface is selected, the installer will skip ahead to the menu shown in <<bsdinstall-configure-net-ipv4>>.
 If a wireless network interface is chosen, the system will instead scan for wireless access points:
 
 [[bsdinstall-wireless-scan]]
 .Scanning for Wireless Access Points
 image::bsdinstall-configure-wireless-scan.png[]
 
 Wireless networks are identified by a Service Set Identifier (SSID), a short, unique name given to each network.
 SSIDs found during the scan are listed, followed by a description of the encryption types available for that network.
 If the desired SSID does not appear in the list, select btn:[Rescan] to scan again.
 If the desired network still does not appear, check for problems with antenna connections or try moving the computer closer to the access point.
 Rescan after each change is made.
 
 [[bsdinstall-wireless-accesspoints]]
 .Choosing a Wireless Network
 image::bsdinstall-configure-wireless-accesspoints.png[]
 
 Next, enter the encryption information for connecting to the selected wireless network.
 WPA2 encryption is strongly recommended as older encryption types, like WEP, offer little security.
 If the network uses WPA2, input the password, also known as the Pre-Shared Key (PSK).
 For security reasons, the characters typed into the input box are displayed as asterisks.
 
 [[bsdinstall-wireless-wpa2]]
 .WPA2 Setup
 image::bsdinstall-configure-wireless-wpa2setup.png[]
 
 Next, choose whether or not an IPv4 address should be configured on the Ethernet or wireless interface:
 
 [[bsdinstall-configure-net-ipv4]]
 .Choose IPv4 Networking
 image::bsdinstall-configure-network-interface-ipv4.png[]
 
 There are two methods of IPv4 configuration.
 DHCP will automatically configure the network interface correctly and should be used if the network provides a DHCP server.
 Otherwise, the addressing information needs to be input manually as a static configuration.
 
 [NOTE]
 ====
 Do not enter random network information as it will not work.
 If a DHCP server is not available, obtain the information listed in <<bsdinstall-collect-network-information, Required Network Information>> from the network administrator or Internet service provider.
 ====
 
 If a DHCP server is available, select btn:[Yes] in the next menu to automatically configure the network interface.
 The installer will appear to pause for a minute or so as it finds the DHCP server and obtains the addressing information for the system.
 
 [[bsdinstall-net-ipv4-dhcp]]
 .Choose IPv4DHCP Configuration
 image::bsdinstall-configure-network-interface-ipv4-dhcp.png[]
 
 If a DHCP server is not available, select btn:[No] and input the following addressing information in this menu:
 
 [[bsdinstall-net-ipv4-static]]
 .IPv4 Static Configuration
 image::bsdinstall-configure-network-interface-ipv4-static.png[]
 
 * `IP Address` - The IPv4 address assigned to this computer. The address must be unique and not already in use by another piece of equipment on the local network.
 * `Subnet Mask` - The subnet mask for the network.
 * `Default Router` - The IP address of the network's default gateway.
 
 The next screen will ask if the interface should be configured for IPv6. If IPv6 is available and desired, choose btn:[Yes] to select it.
 
 [[bsdinstall-net-ipv6]]
 .Choose IPv6 Networking
 image::bsdinstall-configure-network-interface-ipv6.png[]
 
 IPv6 also has two methods of configuration.
 StateLess Address AutoConfiguration (SLAAC) will automatically request the correct configuration information from a local router.
 Refer to http://tools.ietf.org/html/rfc4862[rfc4862] for more information.
 Static configuration requires manual entry of network information.
 
 If an IPv6 router is available, select btn:[Yes] in the next menu to automatically configure the network interface.
 The installer will appear to pause for a minute or so as it finds the router and obtains the addressing information for the system.
 
 [[bsdinstall-net-ipv6-slaac]]
 .Choose IPv6 SLAAC Configuration
 image::bsdinstall-configure-network-interface-slaac.png[]
 
 If an IPv6 router is not available, select btn:[No] and input the following addressing information in this menu:
 
 [[bsdinstall-net-ipv6-static]]
 .IPv6 Static Configuration
 image::bsdinstall-configure-network-interface-ipv6-static.png[]
 
 * `IPv6 Address` - The IPv6 address assigned to this computer. The address must be unique and not already in use by another piece of equipment on the local network.
 * `Default Router` - The IPv6 address of the network's default gateway.
 
 The last network configuration menu is used to configure the Domain Name System (DNS) resolver, which converts hostnames to and from network addresses.
 If DHCP or SLAAC was used to autoconfigure the network interface, the `Resolver Configuration` values may already be filled in.
 Otherwise, enter the local network's domain name in the `Search` field.
 `DNS #1` and `DNS #2` are the IPv4 and/or IPv6 addresses of the DNS servers.
 At least one DNS server is required.
 
 [[bsdinstall-net-dns-config]]
 .DNS Configuration
 image::bsdinstall-configure-network-ipv4-dns.png[]
 
 Once the interface is configured, select a mirror site that is located in the same region of the world as the computer on which FreeBSD is being installed. 
 Files can be retrieved more quickly when the mirror is close to the target computer, reducing installation time.
 
 [[bsdinstall-netinstall-mirror]]
 .Choosing a Mirror
 image::bsdinstall-netinstall-mirrorselect.png[]
 
 [[bsdinstall-install-trouble]]
 == Troubleshooting
 
 This section covers basic installation troubleshooting, such as common problems people have reported.
 
 Check the Hardware Notes (link:https://www.FreeBSD.org/releases/[https://www.freebsd.org/releases/]) document for the version of FreeBSD to make sure the hardware is supported.
 If the hardware is supported and lock-ups or other problems occur, build a custom kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel] to add support for devices which are not present in the [.filename]#GENERIC# kernel. 
 The default kernel assumes that most hardware devices are in their factory default configuration in terms of IRQs, I/O addresses, and DMA channels.
 If the hardware has been reconfigured, a custom kernel configuration file can tell FreeBSD where to find things.
 
 [NOTE]
 ====
 Some installation problems can be avoided or alleviated by updating the firmware on various hardware components, most notably the motherboard. 
 Motherboard firmware is usually referred to as the BIOS.
 Most motherboard and computer manufacturers have a website for upgrades and upgrade information.
 
 Manufacturers generally advise against upgrading the motherboard BIOS unless there is a good reason for doing so, like a critical update.
 The upgrade process _can_ go wrong, leaving the BIOS incomplete and the computer inoperative.
 ====
 
 If the system hangs while probing hardware during boot, or it behaves strangely during install, ACPI may be the culprit.
 FreeBSD makes extensive use of the system ACPI service on the i386 and amd64 platforms to aid in system configuration if it is detected during boot. 
 Unfortunately, some bugs still exist in both the ACPI driver and within system motherboards and BIOS firmware.
 ACPI can be disabled by setting the `hint.acpi.0.disabled` hint in the third stage boot loader:
 
 [source,shell]
 ....
  set hint.acpi.0.disabled="1"
 ....
 
 This is reset each time the system is booted, so it is necessary to add `hint.acpi.0.disabled="1"` to the file [.filename]#/boot/loader.conf#.
 More information about the boot loader can be found in crossref:boot[boot-synopsis,“Synopsis”].
 
 [[using-live-cd]]
 == Using the Live CD
 
 The welcome menu of bsdinstall, shown in <<bsdinstall-choose-mode>>, provides a btn:[Live CD] option.
 This is useful for those who are still wondering whether FreeBSD is the right operating system for them and want to test some of the features before installing.
 
 The following points should be noted before using the btn:[Live CD]:
 
 * To gain access to the system, authentication is required. The username is `root` and the password is blank.
 * As the system runs directly from the installation media, performance will be significantly slower than that of a system installed on a hard disk.
 * This option only provides a command prompt and not a graphical interface.
diff --git a/documentation/content/en/books/handbook/cutting-edge/_index.adoc b/documentation/content/en/books/handbook/cutting-edge/_index.adoc
index b9d4edbda9..c8ac2a5597 100644
--- a/documentation/content/en/books/handbook/cutting-edge/_index.adoc
+++ b/documentation/content/en/books/handbook/cutting-edge/_index.adoc
@@ -1,1037 +1,1037 @@
 ---
 title: Chapter 24. Updating and Upgrading FreeBSD
 part: Part III. System Administration
 prev: books/handbook/l10n
 next: books/handbook/dtrace
 description: Information about how to keep a FreeBSD system up-to-date with freebsd-update or Git, how to rebuild and reinstall the entire base system, etc
 tags: ["updating", "upgrading", "documentation", "FreeBSD-STABLE", "FreeBSD-CURRENT", "Security Patches"]
 ---
 
 [[updating-upgrading]]
 = Updating and Upgrading FreeBSD
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 24
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/cutting-edge/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/cutting-edge/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/cutting-edge/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[updating-upgrading-synopsis]]
 == Synopsis
 
 FreeBSD is under constant development between releases.
 Some people prefer to use the officially released versions, while others prefer to keep in sync with the latest developments.
 However, even official releases are often updated with security and other critical fixes.
 Regardless of the version used, FreeBSD provides all the necessary tools to keep the system updated, and allows for easy upgrades between versions.
 This chapter describes how to track the development system and the basic tools for keeping a FreeBSD system up-to-date.
 
 After reading this chapter, you will know:
 
 * How to keep a FreeBSD system up-to-date with freebsd-update or Git.
 * How to compare the state of an installed system against a known pristine copy.
 * How to keep the installed documentation up-to-date with Git or documentation ports.
 * The difference between the two development branches: FreeBSD-STABLE and FreeBSD-CURRENT.
 * How to rebuild and reinstall the entire base system.
 
 Before reading this chapter, you should:
 
 * Properly set up the network connection (crossref:advanced-networking[advanced-networking,Advanced Networking]).
 * Know how to install additional third-party software (crossref:ports[ports,Installing Applications: Packages and Ports]).
 
 [NOTE]
 ====
 Throughout this chapter, `git` is used to obtain and update FreeBSD sources.
 Optionally, the package:devel/git[] port or package may be used.
 ====
 
 [[updating-upgrading-freebsdupdate]]
 == FreeBSD Update
 
 Applying security patches in a timely manner and upgrading to a newer release of an operating system are important aspects of ongoing system administration.
 FreeBSD includes a utility called `freebsd-update` which can be used to perform both these tasks.
 
 This utility supports binary security and errata updates to FreeBSD, without the need to manually compile and install the patch or a new kernel.
 Binary updates are available for all architectures and releases currently supported by the security team.
 The list of supported releases and their estimated end-of-life dates are listed at https://www.FreeBSD.org/security/[https://www.FreeBSD.org/security/].
 
 This utility also supports operating system upgrades to minor point releases as well as upgrades to another release branch.
 Before upgrading to a new release, review its release announcement as it contains important information pertinent to the release.
 Release announcements are available from https://www.FreeBSD.org/releases/[https://www.FreeBSD.org/releases/].
 
 [NOTE]
 ====
 If a `crontab` utilizing the features of man:freebsd-update[8] exists, it must be disabled before upgrading the operating system.
 ====
 
 This section describes the configuration file used by `freebsd-update`, demonstrates how to apply a security patch and how to upgrade to a minor or major operating system release, and discusses some of the considerations when upgrading the operating system.
 
 [[freebsdupdate-config-file]]
 === The Configuration File
 
 The default configuration file for `freebsd-update` works as-is.
 Some users may wish to tweak the default configuration in [.filename]#/etc/freebsd-update.conf#, allowing better control of the process.
 The comments in this file explain the available options, but the following may require a bit more explanation:
 
 [.programlisting]
 ....
 # Components of the base system which should be kept updated.
 Components world kernel
 ....
 
 This parameter controls which parts of FreeBSD will be kept up-to-date.
 The default is to update the entire base system and the kernel.
 Individual components can instead be specified, such as `src/base` or `src/sys`.
 However, the best option is to leave this at the default as changing it to include specific items requires every needed item to be listed.
 Over time, this could have disastrous consequences as source code and binaries may become out of sync.
 
 [.programlisting]
 ....
 # Paths which start with anything matching an entry in an IgnorePaths
 # statement will be ignored.
 IgnorePaths /boot/kernel/linker.hints
 ....
 
 To leave specified directories, such as [.filename]#/bin# or [.filename]#/sbin#, untouched during the update process, add their paths to this statement.
 This option may be used to prevent `freebsd-update` from overwriting local modifications.
 
 [.programlisting]
 ....
 # Paths which start with anything matching an entry in an UpdateIfUnmodified
 # statement will only be updated if the contents of the file have not been
 # modified by the user (unless changes are merged; see below).
 UpdateIfUnmodified /etc/ /var/ /root/ /.cshrc /.profile
 ....
 
 This option will only update unmodified configuration files in the specified directories.
 Any changes made by the user will prevent the automatic updating of these files.
 There is another option, `KeepModifiedMetadata`, which will instruct `freebsd-update` to save the changes during the merge.
 
 [.programlisting]
 ....
 # When upgrading to a new FreeBSD release, files which match MergeChanges
 # will have any local changes merged into the version from the new release.
 MergeChanges /etc/ /var/named/etc/ /boot/device.hints
 ....
 
 List of directories with configuration files that `freebsd-update` should attempt to merge.
 The file merge process is a series of man:diff[1] patches similar to man:mergemaster[8], but with fewer options.
 Merges are either accepted, open an editor, or cause `freebsd-update` to abort.
 When in doubt, backup [.filename]#/etc# and just accept the merges.
 See man:mergemaster[8] for more information about `mergemaster`.
 
 [.programlisting]
 ....
 # Directory in which to store downloaded updates and temporary
 # files used by FreeBSD Update.
 # WorkDir /var/db/freebsd-update
 ....
 
 This directory is where all patches and temporary files are placed.
 In cases where the user is doing a version upgrade, this location should have at least a gigabyte of disk space available.
 
 [.programlisting]
 ....
 # When upgrading between releases, should the list of Components be
 # read strictly (StrictComponents yes) or merely as a list of components
 # which *might* be installed of which FreeBSD Update should figure out
 # which actually are installed and upgrade those (StrictComponents no)?
 # StrictComponents no
 ....
 
 When this option is set to `yes`, `freebsd-update` will assume that the `Components` list is complete and will not attempt to make changes outside of the list.
 Effectively, `freebsd-update` will attempt to update every file which belongs to the `Components` list.
 
 [[freebsdupdate-security-patches]]
 === Applying Security Patches
 
 The process of applying FreeBSD security patches has been simplified, allowing an administrator to keep a system fully patched using `freebsd-update`. 
 More information about FreeBSD security advisories can be found in crossref:security[security-advisories,"FreeBSD Security Advisories"].
 
 FreeBSD security patches may be downloaded and installed using the following commands.
 The first command will determine if any outstanding patches are available, and if so, will list the files that will be modifed if the patches are applied.
 The second command will apply the patches.
 
 [source,shell]
 ....
 # freebsd-update fetch
 # freebsd-update install
 ....
 
 If the update applies any kernel patches, the system will need a reboot in order to boot into the patched kernel.
 If the patch was applied to any running binaries, the affected applications should be restarted so that the patched version of the binary is used.
 
 [NOTE]
 ====
 Usually, the user needs to be prepared to reboot the system.
 To know if a reboot is required by a kernel update, execute the commands `freebsd-version -k` and `uname -r` and if it differs a reboot is required.
 ====
 
 The system can be configured to automatically check for updates once every day by adding this entry to [.filename]#/etc/crontab#:
 
 [.programlisting]
 ....
 @daily                                  root    freebsd-update cron
 ....
 
 If patches exist, they will automatically be downloaded but will not be applied.
 The `root` user will be sent an email so that the patches may be reviewed and manually installed with `freebsd-update install`.
 
 If anything goes wrong, `freebsd-update` has the ability to roll back the last set of changes with the following command:
 
 [source,shell]
 ....
 # freebsd-update rollback
 Uninstalling updates... done.
 ....
 
 Again, the system should be restarted if the kernel or any kernel modules were modified and any affected binaries should be restarted.
 
 Only the [.filename]#GENERIC# kernel can be automatically updated by `freebsd-update`.
 If a custom kernel is installed, it will have to be rebuilt and reinstalled after `freebsd-update` finishes installing the updates.
 The default kernel name is _GENERIC_.
 The man:uname[1] command may be used to verify its installation.
 
 [NOTE]
 ====
 Always keep a copy of the [.filename]#GENERIC# kernel in [.filename]#/boot/GENERIC#.
 It will be helpful in diagnosing a variety of problems and in performing version upgrades.
 Refer to <<freebsd-update-custom-kernel-9x>> for instructions on how to get a copy of the [.filename]#GENERIC# kernel.
 ====
 
 Unless the default configuration in [.filename]#/etc/freebsd-update.conf# has been changed,
 `freebsd-update` will install the updated kernel sources along with the rest of the updates.
 Rebuilding and reinstalling a new custom kernel can then be performed in the usual way.
 
 The updates distributed by `freebsd-update` do not always involve the kernel.
 It is not necessary to rebuild a custom kernel if the kernel sources have not been modified by `freebsd-update install`.
 However, `freebsd-update` will always update [.filename]#/usr/src/sys/conf/newvers.sh#.
 The current patch level, as indicated by the `-p` number reported by `uname -r`, is obtained from this file.
 Rebuilding a custom kernel, even if nothing else changed, allows `uname` to accurately report the current patch level of the system.
 This is particularly helpful when maintaining multiple systems, as it allows for a quick assessment of the updates installed in each one.
 
 [[freebsdupdate-upgrade]]
 === Performing Major and Minor Version Upgrades
 
 Upgrades from one minor version of FreeBSD to another, like from FreeBSD 9.0 to FreeBSD 9.1, are called _minor version_ upgrades.
 _Major version_ upgrades occur when FreeBSD is upgraded from one major version to another, like from FreeBSD 9.X to FreeBSD 10.X.
 Both types of upgrades can be performed by providing `freebsd-update` with a release version target.
 
 [NOTE]
 ====
 If the system is running a custom kernel, make sure that a copy of the [.filename]#GENERIC# kernel exists in [.filename]#/boot/GENERIC# before starting the upgrade.
 Refer to <<freebsd-update-custom-kernel-9x>> for instructions on how to get a copy of the [.filename]#GENERIC# kernel.
 ====
 
 The following command, when run on a FreeBSD 9.0 system, will upgrade it to FreeBSD 9.1:
 
 [source,shell]
 ....
 # freebsd-update -r 9.1-RELEASE upgrade
 ....
 
 After the command has been received, `freebsd-update` will evaluate the configuration file and current system in an attempt to gather the information necessary to perform the upgrade.
 A screen listing will display which components have and have not been detected.
 For example:
 
 [source,shell]
 ....
 Looking up update.FreeBSD.org mirrors... 1 mirrors found.
 Fetching metadata signature for 9.0-RELEASE from update1.FreeBSD.org... done.
 Fetching metadata index... done.
 Inspecting system... done.
 
 The following components of FreeBSD seem to be installed:
 kernel/smp src/base src/bin src/contrib src/crypto src/etc src/games
 src/gnu src/include src/krb5 src/lib src/libexec src/release src/rescue
 src/sbin src/secure src/share src/sys src/tools src/ubin src/usbin
 world/base world/info world/lib32 world/manpages
 
 The following components of FreeBSD do not seem to be installed:
 kernel/generic world/catpages world/dict world/doc world/games
 world/proflibs
 
 Does this look reasonable (y/n)? y
 ....
 
 At this point, `freebsd-update` will attempt to download all files required for the upgrade.
 In some cases, the user may be prompted with questions regarding what to install or how to proceed.
 
 When using a custom kernel, the above step will produce a warning similar to the following:
 
 [source,shell]
 ....
 WARNING: This system is running a "MYKERNEL" kernel, which is not a
 kernel configuration distributed as part of FreeBSD 9.0-RELEASE.
 This kernel will not be updated: you MUST update the kernel manually
 before running "/usr/sbin/freebsd-update install"
 ....
 
 This warning may be safely ignored at this point.
 The updated [.filename]#GENERIC# kernel will be used as an intermediate step in the upgrade process.
 
 Once all the patches have been downloaded to the local system, they will be applied.
 This process may take a while, depending on the speed and workload of the machine.
 Configuration files will then be merged.
 The merging process requires some user intervention as a file may be merged or an editor may appear on screen for a manual merge.
 The results of every successful merge will be shown to the user as the process continues.
 A failed or ignored merge will cause the process to abort.
 Users may wish to make a backup of [.filename]#/etc# and manually merge important files,
 such as [.filename]#master.passwd# or [.filename]#group# at a later time.
 
 [NOTE]
 ====
 The system is not being altered yet as all patching and merging is happening in another directory.
 Once all patches have been applied successfully,
 all configuration files have been merged and it seems the process will go smoothly,
 the changes can be committed to disk by the user using the following command:
 
 [source,shell]
 ....
 # freebsd-update install
 ....
 
 ====
 
 The kernel and kernel modules will be patched first.
 If the system is running with a custom kernel,
 use man:nextboot[8] to set the kernel for the next boot to the updated [.filename]#/boot/GENERIC#:
 
 [source,shell]
 ....
 # nextboot -k GENERIC
 ....
 
 [WARNING]
 ====
 Before rebooting with the [.filename]#GENERIC# kernel,
 make sure it contains all the drivers required for the system to boot properly and connect to the network,
 if the machine being updated is accessed remotely.
 In particular, if the running custom kernel contains built-in functionality usually provided by kernel modules, make sure to temporarily load these modules into the [.filename]#GENERIC# kernel using the [.filename]#/boot/loader.conf# facility.
 It is recommended to disable non-essential services as well as any disk and network mounts until the upgrade process is complete.
 ====
 
 The machine should now be restarted with the updated kernel:
 
 [source,shell]
 ....
 # shutdown -r now
 ....
 
 Once the system has come back online, restart `freebsd-update` using the following command.
 Since the state of the process has been saved, `freebsd-update` will not start from the beginning,
 but will instead move on to the next phase and remove all old shared libraries and object files.
 
 [source,shell]
 ....
 # freebsd-update install
 ....
 
 [NOTE]
 ====
 Depending upon whether any library version numbers were bumped, there may only be two install phases instead of three.
 ====
 
 The upgrade is now complete.
 If this was a major version upgrade, reinstall all ports and packages as described in <<freebsdupdate-portsrebuild>>.
 
 [[freebsd-update-custom-kernel-9x]]
 ==== Custom Kernels with FreeBSD 9.X and Later
 
 Before using `freebsd-update`, ensure that a copy of the [.filename]#GENERIC# kernel exists in [.filename]#/boot/GENERIC#.
 If a custom kernel has only been built once, the kernel in [.filename]#/boot/kernel.old# is the `GENERIC` kernel.
 Simply rename this directory to [.filename]#/boot/GENERIC#.
 
 If a custom kernel has been built more than once or if it is unknown how many times the custom kernel has been built,
 obtain a copy of the `GENERIC` kernel that matches the current version of the operating system.
 If physical access to the system is available, a copy of the `GENERIC` kernel can be installed from the installation media:
 
 [source,shell]
 ....
 # mount /cdrom
 # cd /cdrom/usr/freebsd-dist
 # tar -C/ -xvf kernel.txz boot/kernel/kernel
 ....
 
 Alternately, the `GENERIC` kernel may be rebuilt and installed from source:
 
 [source,shell]
 ....
 # cd /usr/src
 # make kernel __MAKE_CONF=/dev/null SRCCONF=/dev/null
 ....
 
 For this kernel to be identified as the `GENERIC` kernel by `freebsd-update`,
 the [.filename]#GENERIC# configuration file must not have been modified in any way.
 It is also suggested that the kernel is built without any other special options.
 
 Rebooting into the [.filename]#GENERIC# kernel is not required as `freebsd-update` only needs [.filename]#/boot/GENERIC# to exist.
 
 [[freebsdupdate-portsrebuild]]
 ==== Upgrading Packages After a Major Version Upgrade
 
 Generally, installed applications will continue to work without problems after minor version upgrades.
 Major versions use different Application Binary Interfaces (ABIs), which will break most third-party applications.
 After a major version upgrade, all installed packages and ports need to be upgraded.
 Packages can be upgraded using `pkg upgrade`.
 To upgrade installed ports, use a utility such as package:ports-mgmt/portmaster[].
 
 A forced upgrade of all installed packages will replace the packages with fresh versions from the repository even if the version number has not increased. 
 This is required because of the ABI version change when upgrading between major versions of FreeBSD.
 The forced upgrade can be accomplished by performing:
 
 [source,shell]
 ....
 # pkg-static upgrade -f
 ....
 
 A rebuild of all installed applications can be accomplished with this command:
 
 [source,shell]
 ....
 # portmaster -af
 ....
 
 This command will display the configuration screens for each application that has configurable options and wait for the user to interact with those screens. 
 To prevent this behavior, and use only the default options, include `-G` in the above command.
 
 Once the software upgrades are complete,
 finish the upgrade process with a final call to `freebsd-update` in order to tie up all the loose ends in the upgrade process:
 
 [source,shell]
 ....
 # freebsd-update install
 ....
 
 If the [.filename]#GENERIC# kernel was temporarily used,
 this is the time to build and install a new custom kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel].
 
 Reboot the machine into the new FreeBSD version.
 The upgrade process is now complete.
 
 [[freebsdupdate-system-comparison]]
 === System State Comparison
 
 The state of the installed FreeBSD version against a known good copy can be tested using `freebsd-update IDS`.
 This command evaluates the current version of system utilities, libraries, and configuration files and can be used as a built-in Intrusion Detection System (IDS).
 
 [WARNING]
 ====
 This command is not a replacement for a real IDS such as package:security/snort[].
 As `freebsd-update` stores data on disk, the possibility of tampering is evident.
 While this possibility may be reduced using `kern.securelevel` and by storing the `freebsd-update` data on a read-only file system when not in use,
 a better solution would be to compare the system against a secure disk, such as a DVD or securely stored external USB disk device.
 An alternative method for providing IDS functionality using a built-in utility is described in crossref:security[security-ids,"Binary Verification"]
 ====
 
 To begin the comparison, specify the output file to save the results to:
 
 [source,shell]
 ....
 # freebsd-update IDS >> outfile.ids
 ....
 
 The system will now be inspected and a lengthy listing of files, along with the SHA256 hash values for both the known value in the release and the current installation, will be sent to the specified output file.
 
 The entries in the listing are extremely long, but the output format may be easily parsed.
 For instance, to obtain a list of all files which differ from those in the release, issue the following command:
 
 [source,shell]
 ....
 # cat outfile.ids | awk '{ print $1 }' | more
 /etc/master.passwd
 /etc/motd
 /etc/passwd
 /etc/pf.conf
 ....
 
 This sample output has been truncated as many more files exist.
 Some files have natural modifications.
 For example, [.filename]#/etc/passwd# will be modified if users have been added to the system.
 Kernel modules may differ as `freebsd-update` may have updated them.
 To exclude specific files or directories, add them to the `IDSIgnorePaths` option in [.filename]#/etc/freebsd-update.conf#.
 
 [[updating-upgrading-documentation]]
 == Updating the Documentation Set
 
 Documentation is an integral part of the FreeBSD operating system.
 While an up-to-date version of the FreeBSD documentation is always available on the FreeBSD web site (link:https://docs.FreeBSD.org[Documentation Portal]), it can be handy to have an up-to-date, local copy of the FreeBSD website, handbooks, FAQ, and articles.
 
 This section describes how to use either source or the FreeBSD Ports Collection to keep a local copy of the FreeBSD documentation up-to-date.
 
 For information on editing and submitting corrections to the documentation,
 refer to the FreeBSD Documentation Project Primer for New Contributors (link:{fdp-primer}[FreeBSD Documentation Project Primer for New Contributors]).
 
 [[updating-installed-documentation]]
 === Updating Documentation from Source
 
 Rebuilding the FreeBSD documentation from source requires a collection of tools which are not part of the FreeBSD base system.
 The required tools can be installed following link:{fdp-primer}#overview-quick-start[these steps] from the FreeBSD Documentation Project Primer.
 
 Once installed, use `git` to fetch a clean copy of the documentation source:
 
 [source,shell]
 ....
 # git clone https://git.FreeBSD.org/doc.git /usr/doc
 ....
 
 The initial download of the documentation sources may take a while.
 Let it run until it completes.
 
 Future updates of the documentation sources may be fetched by running:
 
 [source,shell]
 ....
 # git pull
 ....
 
 Once an up-to-date snapshot of the documentation sources has been fetched to [.filename]#/usr/doc#,
 everything is ready for an update of the installed documentation.
 
 A full update may be performed by typing:
 
 [source,shell]
 ....
 # cd /usr/doc
 # make
 ....
 
 [[current-stable]]
 == Tracking a Development Branch
 
 FreeBSD has two development branches: FreeBSD-CURRENT and FreeBSD-STABLE.
 
 This section provides an explanation of each branch and its intended audience, as well as how to keep a system up-to-date with each respective branch.
 
 [[current]]
 === Using FreeBSD-CURRENT
 
 FreeBSD-CURRENT is the "bleeding edge" of FreeBSD development and FreeBSD-CURRENT users are expected to have a high degree of technical skill.
 Less technical users who wish to track a development branch should track FreeBSD-STABLE instead.
 
 FreeBSD-CURRENT is the very latest source code for FreeBSD and includes works in progress, experimental changes, and transitional mechanisms that might or might not be present in the next official release.
 While many FreeBSD developers compile the FreeBSD-CURRENT source code daily, there are short periods of time when the source may not be buildable. 
 These problems are resolved as quickly as possible, but whether or not FreeBSD-CURRENT brings disaster or new functionality can be a matter of when the source code was synced.
 
 FreeBSD-CURRENT is made available for three primary interest groups:
 
 . Members of the FreeBSD community who are actively working on some part of the source tree.
 . Members of the FreeBSD community who are active testers. They are willing to spend time solving problems, making topical suggestions on changes and the general direction of FreeBSD, and submitting patches.
 . Users who wish to keep an eye on things, use the current source for reference purposes, or make the occasional comment or code contribution.
 
 FreeBSD-CURRENT should _not_ be considered a fast-track to getting new features before the next release as pre-release features are not yet fully tested and most likely contain bugs.
 It is not a quick way of getting bug fixes as any given commit is just as likely to introduce new bugs as to fix existing ones.
 FreeBSD-CURRENT is not in any way "officially supported".
 
 To track FreeBSD-CURRENT:
 
 . Join the {freebsd-current} and the {dev-commits-src-main} lists. This is _essential_ in order to see the comments that people are making about the current state of the system and to receive important bulletins about the current state of FreeBSD-CURRENT.
-+ 
++
 The {dev-commits-src-main} list records the commit log entry for each change as it is made, along with any pertinent information on possible side effects.
-+ 
++
 To join these lists, go to {mailman-lists}, click on the list to subscribe to, and follow the instructions.
 In order to track changes to the whole source tree, not just the changes to FreeBSD-CURRENT, subscribe to the {dev-commits-src-all}.
 . Synchronize with the FreeBSD-CURRENT sources. Typically, `git` is used to check out the -CURRENT code from the `main` branch of the FreeBSD Git repository (see crossref:mirrors[git,“Using Git”] for details).
 . Due to the size of the repository, some users choose to only synchronize the sections of source that interest them or which they are contributing patches to. However, users that plan to compile the operating system from source must download _all_ of FreeBSD-CURRENT, not just selected portions.
-+ 
++
 Before compiling FreeBSD-CURRENT, read [.filename]#/usr/src/Makefile# very carefully and follow the instructions in <<makeworld>>.
 Read the {freebsd-current} and [.filename]#/usr/src/UPDATING# to stay up-to-date on other bootstrapping procedures that sometimes become necessary on the road to the next release.
 . Be active! FreeBSD-CURRENT users are encouraged to submit their suggestions for enhancements or bug fixes. Suggestions with accompanying code are always welcome.
 
 [[stable]]
 === Using FreeBSD-STABLE
 
 FreeBSD-STABLE is the development branch from which major releases are made.
 Changes go into this branch at a slower pace and with the general assumption that they have first been tested in FreeBSD-CURRENT.
 This is _still_ a development branch and, at any given time, the sources for FreeBSD-STABLE may or may not be suitable for general use.
 It is simply another engineering development track, not a resource for end-users.
 Users who do not have the resources to perform testing should instead run the most recent release of FreeBSD.
 
 Those interested in tracking or contributing to the FreeBSD development process, especially as it relates to the next release of FreeBSD, should consider following FreeBSD-STABLE.
 
 While the FreeBSD-STABLE branch should compile and run at all times, this cannot be guaranteed.
 Since more people run FreeBSD-STABLE than FreeBSD-CURRENT, it is inevitable that bugs and corner cases will sometimes be found in FreeBSD-STABLE that were not apparent in FreeBSD-CURRENT.
 For this reason, one should not blindly track FreeBSD-STABLE.
 It is particularly important _not_ to update any production servers to FreeBSD-STABLE without thoroughly testing the code in a development or testing environment.
 
 To track FreeBSD-STABLE:
 
 . Join the {freebsd-stable} in order to stay informed of build dependencies that may appear in FreeBSD-STABLE or any other issues requiring special attention. Developers will also make announcements in this mailing list when they are contemplating some controversial fix or update, giving the users a chance to respond if they have any issues to raise concerning the proposed change.
-+ 
++
 Join the relevant git list for the branch being tracked.
 For example, users tracking the {betarel-current-major}-STABLE branch should join the {dev-commits-src-branches}.
 This list records the commit log entry for each change as it is made, along with any pertinent information on possible side effects.
-+ 
++
 To join these lists, go to {mailman-lists}, click on the list to subscribe to, and follow the instructions.
 In order to track changes for the whole source tree, subscribe to {dev-commits-src-all}.
 . To install a new FreeBSD-STABLE system, install the most recent FreeBSD-STABLE release from the crossref:mirrors[mirrors,FreeBSD mirror sites] or use a monthly snapshot built from FreeBSD-STABLE. Refer to link:https://www.FreeBSD.org/snapshots/[www.freebsd.org/snapshots] for more information about snapshots.
-+ 
++
 To compile or upgrade to an existing FreeBSD system to FreeBSD-STABLE, use `git` to check out the source for the desired branch.
 Branch names, such as `stable/9`, are listed at link:https://www.FreeBSD.org/releng/[www.freebsd.org/releng].
 . Before compiling or upgrading to FreeBSD-STABLE , read [.filename]#/usr/src/Makefile# carefully and follow the instructions in <<makeworld>>. Read the {freebsd-stable} and [.filename]#/usr/src/UPDATING# to keep up-to-date on other bootstrapping procedures that sometimes become necessary on the road to the next release.
 
 [[makeworld]]
 == Updating FreeBSD from Source
 
 Updating FreeBSD by compiling from source offers several advantages over binary updates.
 Code can be built with options to take advantage of specific hardware.
 Parts of the base system can be built with non-default settings, or left out entirely where they are not needed or desired.
 The build process takes longer to update a system than just installing binary updates, but allows complete customization to produce a tailored version of FreeBSD.
 
 [[updating-src-quick-start]]
 === Quick Start
 
 This is a quick reference for the typical steps used to update FreeBSD by building from source.
 Later sections describe the process in more detail.
 
 [.procedure]
 ====
 * Update and Build
 +
 [source,shell]
 ....
 # git pull /usr/src  <.>
 check /usr/src/UPDATING  <.>
 # cd /usr/src          <.>
 # make -j4 buildworld  <.>
 # make -j4 kernel      <.>
 # shutdown -r now      <.>
 # etcupdate -p         <.>
 # cd /usr/src          <.>
 # make installworld    <.>
 # etcupdate -B         <.>
 # shutdown -r now      <.>
 ....
 
 <.> Get the latest version of the source. See <<updating-src-obtaining-src>> for more information on obtaining and updating source.
 
 <.> Check [.filename]#/usr/src/UPDATING# for any manual steps required before or after building from source.
 
 <.> Go to the source directory.
 
 <.> Compile the world, everything except the kernel.
 
 <.> Compile and install the kernel. This is equivalent to `make buildkernel installkernel`.
 
 <.> Reboot the system to the new kernel.
 
 <.> Update and merge configuraton files in [.filename]#/etc/# required before installworld.
 
 <.> Go to the source directory.
 
 <.> Install the world.
 
 <.> Update and merge configuration files in [.filename]#/etc/#.
 
 <.> Restart the system to use the newly-built world and kernel.
 ====
 
 [[updating-src-preparing]]
 === Preparing for a Source Update
 
 Read [.filename]#/usr/src/UPDATING#. Any manual steps that must be performed before or after an update are described in this file.
 
 [[updating-src-obtaining-src]]
 === Updating the Source
 
 FreeBSD source code is located in [.filename]#/usr/src/#.
 The preferred method of updating this source is through the Git version control system.
 Verify that the source code is under version control:
 
 [source,shell]
 ....
 # cd /usr/src
 # git remote --v
 origin  https://git.freebsd.org/src.git (fetch)
 origin  https://git.freebsd.org/src.git (push)
 ....
 
 This indicates that [.filename]#/usr/src/# is under version control and can be updated with man:git[1]:
 
 [[synching]]
 [source,shell]
 ....
 # git pull /usr/src
 ....
 
 The update process can take some time if the directory has not been updated recently.
 After it finishes, the source code is up to date and the build process described in the next section can begin.
 
 [NOTE]
 ====
 *Obtaining the Source:* +
 
 If the output says `fatal: not a git repository`, the files there are missing or were installed with a different method.
 A new checkout of the source is required.
 
 [[updating-src-obtaining-src-repopath]]
 .FreeBSD Versions and Repository Branchs
 [cols="10%,10%,80%", options="header"]
 |===
 | uname -r Output
 | Repository Path
 | Description
 
 |`_X.Y_-RELEASE`
 |`releng/_X.Y_`
 |The Release version plus only critical security and bug fix patches. This branch is recommended for most users.
 
 |`_X.Y_-STABLE`
 |`stable/_X_`
 |
 
 The Release version plus all additional development on that branch. _STABLE_ refers to the Applications Binary Interface (ABI) not changing, so software compiled for earlier versions still runs. For example, software compiled to run on FreeBSD 10.1 will still run on FreeBSD 10-STABLE compiled later.
 
 STABLE branches occasionally have bugs or incompatibilities which might affect users, although these are typically fixed quickly.
 
 |`_X_-CURRENT`
 |`main`
 |The latest unreleased development version of FreeBSD. The CURRENT branch can have major bugs or incompatibilities and is recommended only for advanced users.
 |===
 
 Determine which version of FreeBSD is being used with man:uname[1]:
 
 [source,shell]
 ....
 # uname -r
 10.3-RELEASE
 ....
 
 Based on <<updating-src-obtaining-src-repopath>>, the source used to update `10.3-RELEASE` has a repository path of `releng/10.3`. That path is used when checking out the source:
 
 [source,shell]
 ....
 # mv /usr/src /usr/src.bak <.>
 # git clone --branch releng/10.3 https://git.FreeBSD.org/src.git /usr/src <.>
 ....
 
 <.> Move the old directory out of the way. If there are no local modifications in this directory, it can be deleted.
 
 <.> The path from <<updating-src-obtaining-src-repopath>> is added to the repository URL. The third parameter is the destination directory for the source code on the local system.
 ====
 
 [[updating-src-building]]
 === Building from Source
 
 The _world_, or all of the operating system except the kernel, is compiled.
 This is done first to provide up-to-date tools to build the kernel.
 Then the kernel itself is built:
 
 [source,shell]
 ....
 # cd /usr/src
 # make buildworld
 # make buildkernel
 ....
 
 The compiled code is written to [.filename]#/usr/obj#.
 
 These are the basic steps.
 Additional options to control the build are described below.
 
 [[updating-src-building-clean-build]]
 ==== Performing a Clean Build
 
 Some versions of the FreeBSD build system leave previously-compiled code in the temporary object directory, [.filename]#/usr/obj#.
 This can speed up later builds by avoiding recompiling code that has not changed.
 To force a clean rebuild of everything, use `cleanworld` before starting a build:
 
 [source,shell]
 ....
 # make cleanworld
 ....
 
 [[updating-src-building-jobs]]
 ==== Setting the Number of Jobs
 
 Increasing the number of build jobs on multi-core processors can improve build speed.
 Determine the number of cores with `sysctl hw.ncpu`.
 Processors vary, as do the build systems used with different versions of FreeBSD, so testing is the only sure method to tell how a different number of jobs affects the build speed.
 For a starting point, consider values between half and double the number of cores.
 The number of jobs is specified with `-j`.
 
 [[updating-src-building-jobs-example]]
 .Increasing the Number of Build Jobs
 [example]
 ====
 Building the world and kernel with four jobs:
 
 [source,shell]
 ....
 # make -j4 buildworld buildkernel
 ....
 
 ====
 
 [[updating-src-building-only-kernel]]
 ==== Building Only the Kernel
 
 A `buildworld` must be completed if the source code has changed.
 After that, a `buildkernel` to build a kernel can be run at any time.
 To build just the kernel:
 
 [source,shell]
 ....
 # cd /usr/src
 # make buildkernel
 ....
 
 [[updating-src-building-custom-kernel]]
 ==== Building a Custom Kernel
 
 The standard FreeBSD kernel is based on a _kernel config file_ called [.filename]#GENERIC#.
 The [.filename]#GENERIC# kernel includes the most commonly-needed device drivers and options.
 Sometimes it is useful or necessary to build a custom kernel, adding or removing device drivers or options to fit a specific need.
 
 For example, someone developing a small embedded computer with severely limited RAM could remove unneeded device drivers or options to make the kernel slightly smaller.
 
 Kernel config files are located in [.filename]#/usr/src/sys/arch/conf/#, where _arch_ is the output from `uname -m`.
 On most computers, that is `amd64`, giving a config file directory of [.filename]#/usr/src/sys/amd64/conf/#.
 
 [TIP]
 ====
 [.filename]#/usr/src# can be deleted or recreated, so it is preferable to keep custom kernel config files in a separate directory, like [.filename]#/root#.
 Link the kernel config file into the [.filename]#conf# directory.
 If that directory is deleted or overwritten, the kernel config can be re-linked into the new one.
 ====
 
 A custom config file can be created by copying the [.filename]#GENERIC# config file.
 In this example, the new custom kernel is for a storage server, so is named [.filename]#STORAGESERVER#:
 
 [source,shell]
 ....
 # cp /usr/src/sys/amd64/conf/GENERIC /root/STORAGESERVER
 # cd /usr/src/sys/amd64/conf
 # ln -s /root/STORAGESERVER .
 ....
 
 [.filename]#/root/STORAGESERVER# is then edited, adding or removing devices or options as shown in man:config[5].
 
 The custom kernel is built by setting `KERNCONF` to the kernel config file on the command line:
 
 [source,shell]
 ....
 # make buildkernel KERNCONF=STORAGESERVER
 ....
 
 [[updating-src-installing]]
 === Installing the Compiled Code
 
 After the `buildworld` and `buildkernel` steps have been completed, the new kernel and world are installed:
 
 [source,shell]
 ....
 # cd /usr/src
 # make installkernel
 # shutdown -r now
 # cd /usr/src
 # make installworld
 # shutdown -r now
 ....
 
 If a custom kernel was built, `KERNCONF` must also be set to use the new custom kernel:
 
 [source,shell]
 ....
 # cd /usr/src
 # make installkernel KERNCONF=STORAGESERVER
 # shutdown -r now
 # cd /usr/src
 # make installworld
 # shutdown -r now
 ....
 
 [[updating-src-completing]]
 === Completing the Update
 
 A few final tasks complete the update.
 Any modified configuration files are merged with the new versions, outdated libraries are located and removed, then the system is restarted.
 
 [[updating-src-completing-merge-etcupdate]]
 ==== Merging Configuration Files with man:etcupdate[8]
 
 man:etcupdate[8] is a tool for managing updates to files that are not updated as part of an installworld such as files located in [.filename]#/etc/#.
 It manages updates by doing a three-way merge of changes made to these files against the local versions.
 It is also designed to minimize the amount of user intervention, in contrast to man:mergemaster[8]'s interactive prompts.
 
 [NOTE]
 ====
 In general, man:etcupdate[8] does not need any specific arguments for its job.
 There is however a handy in between command for sanity checking what will be done the first time man:etcupdate[8] is used:
 
 [source,shell]
 ....
 # etcupdate diff
 ....
 
 This command allows the user to audit configuration changes.
 ====
 
 If man:etcupdate[8] is not able to merge a file automatically, the merge conflicts can be resolved with manual interaction by issuing:
 
 [source,shell]
 ....
 # etcupdate resolve
 ....
 
 [WARNING]
 ====
 When switching from man:mergemaster[8] to man:etcupdate[8], the first run might merge changes incorrectly generating spurious conflicts.
 To prevent this, perform the following steps *before* updating sources and building the new world:
 
 [source,shell]
 ....
 # etcupdate bootstrap <.>
 # etcupdate diff <.>
 ....
 
 <.> Bootstrap the database of stock [.filename]#/etc# files, for more information see man:etcupdate[8].
 
 <.> Check the diff after bootstrapping. Trim any local changes that are no longer needed to reduce the chance of conflicts in future updates.
 ====
 
 [[updating-src-completing-merge-mergemaster]]
 ==== Merging Configuration Files with man:mergemaster[8]
 
 man:mergemaster[8] provides a way to merge changes that have been made to system configuration files with new versions of those files.
 man:mergemaster[8] is an alternative to the preferred man:etcupdate[8]
 With `-Ui`, man:mergemaster[8] automatically updates files that have not been user-modified and installs new files that are not already present:
 
 [source,shell]
 ....
 # mergemaster -Ui
 ....
 
 If a file must be manually merged, an interactive display allows the user to choose which portions of the files are kept.
 See man:mergemaster[8] for more information.
 
 [[updating-src-completing-check-old]]
 ==== Checking for Outdated Files and Libraries
 
 Some obsolete files or directories can remain after an update.
 These files can be located:
 
 [source,shell]
 ....
 # make check-old
 ....
 
 and deleted:
 
 [source,shell]
 ....
 # make delete-old
 ....
 
 Some obsolete libraries can also remain.
 These can be detected with:
 
 [source,shell]
 ....
 # make check-old-libs
 ....
 
 and deleted with
 
 [source,shell]
 ....
 # make delete-old-libs
 ....
 
 Programs which were still using those old libraries will stop working when the library has been deleted.
 These programs must be rebuilt or replaced after deleting the old libraries.
 
 [TIP]
 ====
 When all the old files or directories are known to be safe to delete,
 pressing kbd:[y] and kbd:[Enter] to delete each file can be avoided by setting `BATCH_DELETE_OLD_FILES` in the command.
 For example:
 
 [source,shell]
 ....
 # make BATCH_DELETE_OLD_FILES=yes delete-old-libs
 ....
 
 ====
 
 [[updating-src-completing-restart]]
 ==== Restarting After the Update
 
 The last step after updating is to restart the computer so all the changes take effect:
 
 [source,shell]
 ....
 # shutdown -r now
 ....
 
 [[small-lan]]
 == Tracking for Multiple Machines
 
 When multiple machines need to track the same source tree,
 it is a waste of disk space, network bandwidth,
 and CPU cycles to have each system download the sources and rebuild everything.
 The solution is to have one machine do most of the work, while the rest of the machines mount that work via NFS.
 This section outlines a method of doing so.
 For more information about using NFS, refer to crossref:network-servers[network-nfs,"Network File System (NFS)"].
 
 First, identify a set of machines which will run the same set of binaries, known as a _build set_.
 Each machine can have a custom kernel, but will run the same userland binaries.
 From that set, choose a machine to be the _build machine_ that the world and kernel are built on.
 Ideally, this is a fast machine that has sufficient spare CPU to run `make buildworld` and `make buildkernel`.
 
 Select a machine to be the _test machine_, which will test software updates before they are put into production.
 This _must_ be a machine that can afford to be down for an extended period of time.
 It can be the build machine, but need not be.
 
 All the machines in this build set need to mount [.filename]#/usr/obj# and [.filename]#/usr/src# from the build machine via NFS.
 For multiple build sets, [.filename]#/usr/src# should be on one build machine, and NFS mounted on the rest.
 
 Ensure that [.filename]#/etc/make.conf# and [.filename]#/etc/src.conf# on all the machines in the build set agree with the build machine.
 That means that the build machine must build all the parts of the base system that any machine in the build set is going to install.
 Also, each build machine should have its kernel name set with `KERNCONF` in [.filename]#/etc/make.conf#,
 and the build machine should list them all in its `KERNCONF`, listing its own kernel first.
 The build machine must have the kernel configuration files for each machine in its [.filename]#/usr/src/sys/arch/conf#.
 
 On the build machine, build the kernel and world as described in <<makeworld>>,
 but do not install anything on the build machine.
 Instead, install the built kernel on the test machine.
 On the test machine, mount [.filename]#/usr/src# and [.filename]#/usr/obj# via NFS.
 Then, run `shutdown now` to go to single-user mode in order to install the new kernel and world and run `mergemaster` as usual.
 When done, reboot to return to normal multi-user operations.
 
 After verifying that everything on the test machine is working properly,
 use the same procedure to install the new software on each of the other machines in the build set.
 
 The same methodology can be used for the ports tree.
 The first step is to share [.filename]#/usr/ports# via NFS to all the machines in the build set.
 To configure [.filename]#/etc/make.conf# to share distfiles,
 set `DISTDIR` to a common shared directory that is writable by whichever user `root` is mapped to by the NFS mount.
 Each machine should set `WRKDIRPREFIX` to a local build directory, if ports are to be built locally.
 Alternately, if the build system is to build and distribute packages to the machines in the build set,
 set `PACKAGES` on the build system to a directory similar to `DISTDIR`.
diff --git a/documentation/content/en/books/handbook/disks/_index.adoc b/documentation/content/en/books/handbook/disks/_index.adoc
index 48a25940f0..238c075973 100644
--- a/documentation/content/en/books/handbook/disks/_index.adoc
+++ b/documentation/content/en/books/handbook/disks/_index.adoc
@@ -1,2558 +1,2558 @@
 ---
 title: Chapter 18. Storage
 part: Part III. System Administration
 prev: books/handbook/audit
 next: books/handbook/geom
 description: This chapter covers the use of disks and storage media in FreeBSD. This includes SCSI and IDE disks, CD and DVD media, memory-backed disks, and USB storage devices.
 tags: ["storage", "disks", "gpart", "mount", "quotas", "encrypt", "GPT", "cdrecord", "NTFS", "quotas", "swap", "HAST", "CD", "DVD", "resizing", "growing"]
 ---
 
 [[disks]]
 = Storage
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 18
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/disks/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/disks/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/disks/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[disks-synopsis]]
 == Synopsis
 
 This chapter covers the use of disks and storage media in FreeBSD.
 This includes SCSI and IDE disks, CD and DVD media, memory-backed disks, and USB storage devices.
 
 After reading this chapter, you will know:
 
 * How to add additional hard disks to a FreeBSD system.
 * How to grow the size of a disk's partition on FreeBSD.
 * How to configure FreeBSD to use USB storage devices.
 * How to use CD and DVD media on a FreeBSD system.
 * How to use the backup programs available under FreeBSD.
 * How to set up memory disks.
 * What file system snapshots are and how to use them efficiently.
 * How to use quotas to limit disk space usage.
 * How to encrypt disks and swap to secure them against attackers.
 * How to configure a highly available storage network.
 
 Before reading this chapter, you should:
 
 * Know how to crossref:kernelconfig[kernelconfig,configure and install a new FreeBSD kernel].
 
 [[disks-adding]]
 == Adding Disks
 
 This section describes how to add a new SATA disk to a machine that currently only has a single drive.
 First, turn off the computer and install the drive in the computer following the instructions of the computer, controller, and drive manufacturers.
 Reboot the system and become `root`.
 
 Inspect [.filename]#/var/run/dmesg.boot# to ensure the new disk was found.
 In this example, the newly added SATA drive will appear as [.filename]#ada1#.
 
 For this example, a single large partition will be created on the new disk.
 The http://en.wikipedia.org/wiki/GUID_Partition_Table[GPT] partitioning scheme will be used in preference to the older and less versatile MBR scheme.
 
 [NOTE]
 ====
 If the disk to be added is not blank, old partition information can be removed with `gpart delete`.
 See man:gpart[8] for details.
 ====
 
 The partition scheme is created, and then a single partition is added.
 To improve performance on newer disks with larger hardware block sizes, the partition is aligned to one megabyte boundaries:
 
 [source,shell]
 ....
 # gpart create -s GPT ada1
 # gpart add -t freebsd-ufs -a 1M ada1
 ....
 
 Depending on use, several smaller partitions may be desired.
 See man:gpart[8] for options to create partitions smaller than a whole disk.
 
 The disk partition information can be viewed with `gpart show`:
 
 [source,shell]
 ....
 % gpart show ada1
 =>        34  1465146988  ada1  GPT  (699G)
           34        2014        - free -  (1.0M)
         2048  1465143296     1  freebsd-ufs  (699G)
   1465145344        1678        - free -  (839K)
 ....
 
 A file system is created in the new partition on the new disk:
 
 [source,shell]
 ....
 # newfs -U /dev/ada1p1
 ....
 
 An empty directory is created as a _mountpoint_, a location for mounting the new disk in the original disk's file system:
 
 [source,shell]
 ....
 # mkdir /newdisk
 ....
 
 Finally, an entry is added to [.filename]#/etc/fstab# so the new disk will be mounted automatically at startup:
 
 [.programlisting]
 ....
 /dev/ada1p1	/newdisk	ufs	rw	2	2
 ....
 
 The new disk can be mounted manually, without restarting the system:
 
 [source,shell]
 ....
 # mount /newdisk
 ....
 
 [[disks-growing]]
 == Resizing and Growing Disks
 
 A disk's capacity can increase without any changes to the data already present.
 This happens commonly with virtual machines, when the virtual disk turns out to be too small and is enlarged.
 Sometimes a disk image is written to a USB memory stick, but does not use the full capacity.
 Here we describe how to resize or _grow_ disk contents to take advantage of increased capacity.
 
 Determine the device name of the disk to be resized by inspecting [.filename]#/var/run/dmesg.boot#.
 In this example, there is only one SATA disk in the system, so the drive will appear as [.filename]#ada0#.
 
 List the partitions on the disk to see the current configuration:
 
 [source,shell]
 ....
 # gpart show ada0
 =>      34  83886013  ada0  GPT  (48G) [CORRUPT]
         34       128     1  freebsd-boot  (64k)
        162  79691648     2  freebsd-ufs  (38G)
   79691810   4194236     3  freebsd-swap  (2G)
   83886046         1        - free -  (512B)
 ....
 
 [NOTE]
 ====
 If the disk was formatted with the http://en.wikipedia.org/wiki/GUID_Partition_Table[GPT] partitioning scheme, it may show as "corrupted" because the GPT backup partition table is no longer at the end of the drive.
 Fix the backup partition table with `gpart`:
 
 [source,shell]
 ....
 # gpart recover ada0
 ada0 recovered
 ....
 
 ====
 
 Now the additional space on the disk is available for use by a new partition, or an existing partition can be expanded:
 
 [source,shell]
 ....
 # gpart show ada0
 =>       34  102399933  ada0  GPT  (48G)
          34        128     1  freebsd-boot  (64k)
         162   79691648     2  freebsd-ufs  (38G)
    79691810    4194236     3  freebsd-swap  (2G)
    83886046   18513921        - free -  (8.8G)
 ....
 
 Partitions can only be resized into contiguous free space.
 Here, the last partition on the disk is the swap partition, but the second partition is the one that needs to be resized.
 Swap partitions only contain temporary data, so it can safely be unmounted, deleted, and then recreate the third partition after resizing the second partition.
 
 Disable the swap partition:
 
 [source,shell]
 ....
 # swapoff /dev/ada0p3
 ....
 
 Delete the third partition, specified by the `-i` flag, from the disk _ada0_.
 
 [source,shell]
 ....
 # gpart delete -i 3 ada0
 ada0p3 deleted
 # gpart show ada0
 =>       34  102399933  ada0  GPT  (48G)
          34        128     1  freebsd-boot  (64k)
         162   79691648     2  freebsd-ufs  (38G)
    79691810   22708157        - free -  (10G)
 ....
 
 [WARNING]
 ====
 
 There is risk of data loss when modifying the partition table of a mounted file system.
 It is best to perform the following steps on an unmounted file system while running from a live CD-ROM or USB device.
 However, if absolutely necessary, a mounted file system can be resized after disabling GEOM safety features:
 
 [source,shell]
 ....
 # sysctl kern.geom.debugflags=16
 ....
 
 ====
 
 Resize the partition, leaving room to recreate a swap partition of the desired size.
 The partition to resize is specified with `-i`, and the new desired size with `-s`.
 Optionally, alignment of the partition is controlled with `-a`.
 This only modifies the size of the partition.
 The file system in the partition will be expanded in a separate step.
 
 [source,shell]
 ....
 # gpart resize -i 2 -s 47G -a 4k ada0
 ada0p2 resized
 # gpart show ada0
 =>       34  102399933  ada0  GPT  (48G)
          34        128     1  freebsd-boot  (64k)
         162   98566144     2  freebsd-ufs  (47G)
    98566306    3833661        - free -  (1.8G)
 ....
 
 Recreate the swap partition and activate it.
 If no size is specified with `-s`, all remaining space is used:
 
 [source,shell]
 ....
 # gpart add -t freebsd-swap -a 4k ada0
 ada0p3 added
 # gpart show ada0
 =>       34  102399933  ada0  GPT  (48G)
          34        128     1  freebsd-boot  (64k)
         162   98566144     2  freebsd-ufs  (47G)
    98566306    3833661     3  freebsd-swap  (1.8G)
 # swapon /dev/ada0p3
 ....
 
 Grow the UFS file system to use the new capacity of the resized partition:
 
 [source,shell]
 ....
 # growfs /dev/ada0p2
 Device is mounted read-write; resizing will result in temporary write suspension for /.
 It's strongly recommended to make a backup before growing the file system.
 OK to grow file system on /dev/ada0p2, mounted on /, from 38GB to 47GB? [Yes/No] Yes
 super-block backups (for fsck -b #) at:
  80781312, 82063552, 83345792, 84628032, 85910272, 87192512, 88474752,
  89756992, 91039232, 92321472, 93603712, 94885952, 96168192, 97450432
 ....
 
 If the file system is ZFS, the resize is triggered by running the `online` subcommand with `-e`:
 
 [source,shell]
 ....
 # zpool online -e zroot /dev/ada0p2
 ....
 
 Both the partition and the file system on it have now been resized to use the newly-available disk space.
 
 [[usb-disks]]
 == USB Storage Devices
 
 Many external storage solutions, such as hard drives, USB thumbdrives, and CD and DVD burners, use the Universal Serial Bus (USB).
 FreeBSD provides support for USB 1.x, 2.0, and 3.0 devices.
 
 [NOTE]
 ====
 USB 3.0 support is not compatible with some hardware, including Haswell (Lynx point) chipsets.
 If FreeBSD boots with a `failed with error 19` message, disable xHCI/USB3 in the system BIOS.
 ====
 
 Support for USB storage devices is built into the [.filename]#GENERIC# kernel.
 For a custom kernel, be sure that the following lines are present in the kernel configuration file:
 
 [.programlisting]
 ....
 device scbus	# SCSI bus (required for ATA/SCSI)
 device da	# Direct Access (disks)
 device pass	# Passthrough device (direct ATA/SCSI access)
 device uhci	# provides USB 1.x support
 device ohci	# provides USB 1.x support
 device ehci	# provides USB 2.0 support
 device xhci	# provides USB 3.0 support
 device usb	# USB Bus (required)
 device umass	# Disks/Mass storage - Requires scbus and da
 device cd	# needed for CD and DVD burners
 ....
 
 FreeBSD uses the man:umass[4] driver which uses the SCSI subsystem to access USB storage devices.
 Since any USB device will be seen as a SCSI device by the system, if the USB device is a CD or DVD burner, do _not_ include `device atapicam` in a custom kernel configuration file.
 
 The rest of this section demonstrates how to verify that a USB storage device is recognized by FreeBSD and how to configure the device so that it can be used.
 
 === Device Configuration
 
 To test the USB configuration, plug in the USB device.
 Use `dmesg` to confirm that the drive appears in the system message buffer.
 It should look something like this:
 
 [source,shell]
 ....
 umass0: <STECH Simple Drive, class 0/0, rev 2.00/1.04, addr 3> on usbus0
 umass0:  SCSI over Bulk-Only; quirks = 0x0100
 umass0:4:0:-1: Attached to scbus4
 da0 at umass-sim0 bus 0 scbus4 target 0 lun 0
 da0: <STECH Simple Drive 1.04> Fixed Direct Access SCSI-4 device
 da0: Serial Number WD-WXE508CAN263
 da0: 40.000MB/s transfers
 da0: 152627MB (312581808 512 byte sectors: 255H 63S/T 19457C)
 da0: quirks=0x2<NO_6_BYTE>
 ....
 
 The brand, device node ([.filename]#da0#), speed, and size will differ according to the device.
 
 Since the USB device is seen as a SCSI one, `camcontrol` can be used to list the USB storage devices attached to the system:
 
 [source,shell]
 ....
 # camcontrol devlist
 <STECH Simple Drive 1.04>          at scbus4 target 0 lun 0 (pass3,da0)
 ....
 
 Alternately, `usbconfig` can be used to list the device.
 Refer to man:usbconfig[8] for more information about this command.
 
 [source,shell]
 ....
 # usbconfig
 ugen0.3: <Simple Drive STECH> at usbus0, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON (2mA)
 ....
 
 If the device has not been formatted, refer to <<disks-adding>> for instructions on how to format and create partitions on the USB drive.
 If the drive comes with a file system, it can be mounted by `root` using the instructions in crossref:basics[mount-unmount,“Mounting and Unmounting File Systems”].
 
 [WARNING]
 ====
 Allowing untrusted users to mount arbitrary media, by enabling `vfs.usermount` as described below, should not be considered safe from a security point of view.
 Most file systems were not built to safeguard against malicious devices.
 ====
 
 To make the device mountable as a normal user, one solution is to make all users of the device a member of the `operator` group using man:pw[8].
 Next, ensure that `operator` is able to read and write the device by adding these lines to [.filename]#/etc/devfs.rules#:
 
 [.programlisting]
 ....
 [localrules=5]
 add path 'da*' mode 0660 group operator
 ....
 
 [NOTE]
 ====
 If internal SCSI disks are also installed in the system, change the second line as follows:
 
 [.programlisting]
 ....
 add path 'da[3-9]*' mode 0660 group operator
 ....
 
 This will exclude the first three SCSI disks ([.filename]#da0# to [.filename]#da2#) from belonging to the `operator` group.
 Replace _3_ with the number of internal SCSI disks.
 Refer to man:devfs.rules[5] for more information about this file.
 ====
 
 Next, enable the ruleset in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 devfs_system_ruleset="localrules"
 ....
 
 Then, instruct the system to allow regular users to mount file systems by adding the following line to [.filename]#/etc/sysctl.conf#:
 
 [.programlisting]
 ....
 vfs.usermount=1
 ....
 
 Since this only takes effect after the next reboot, use `sysctl` to set this variable now:
 
 [source,shell]
 ....
 # sysctl vfs.usermount=1
 vfs.usermount: 0 -> 1
 ....
 
 The final step is to create a directory where the file system is to be mounted.
 This directory needs to be owned by the user that is to mount the file system.
 One way to do that is for `root` to create a subdirectory owned by that user as [.filename]#/mnt/username#.
 In the following example, replace _username_ with the login name of the user and _usergroup_ with the user's primary group:
 
 [source,shell]
 ....
 # mkdir /mnt/username
 # chown username:usergroup /mnt/username
 ....
 
 Suppose a USB thumbdrive is plugged in, and a device [.filename]#/dev/da0s1# appears.
 If the device is formatted with a FAT file system, the user can mount it using:
 
 [source,shell]
 ....
 % mount -t msdosfs -o -m=644,-M=755 /dev/da0s1 /mnt/username
 ....
 
 Before the device can be unplugged, it _must_ be unmounted first:
 
 [source,shell]
 ....
 % umount /mnt/username
 ....
 
 After device removal, the system message buffer will show messages similar to the following:
 
 [source,shell]
 ....
 umass0: at uhub3, port 2, addr 3 (disconnected)
 da0 at umass-sim0 bus 0 scbus4 target 0 lun 0
 da0: <STECH Simple Drive 1.04> s/n WD-WXE508CAN263          detached
 (da0:umass-sim0:0:0:0): Periph destroyed
 ....
 
 === Automounting Removable Media
 
 USB devices can be automatically mounted by uncommenting this line in [.filename]#/etc/auto_master#:
 
 [source,shell]
 ....
 /media		-media		-nosuid
 ....
 
 Then add these lines to [.filename]#/etc/devd.conf#:
 
 [source,shell]
 ....
 notify 100 {
 	match "system" "GEOM";
 	match "subsystem" "DEV";
 	action "/usr/sbin/automount -c";
 };
 ....
 
 Reload the configuration if man:autofs[5] and man:devd[8] are already running:
 
 [source,shell]
 ....
 # service automount restart
 # service devd restart
 ....
 
 man:autofs[5] can be set to start at boot by adding this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 autofs_enable="YES"
 ....
 
 man:autofs[5] requires man:devd[8] to be enabled, as it is by default.
 
 Start the services immediately with:
 
 [source,shell]
 ....
 # service automount start
 # service automountd start
 # service autounmountd start
 # service devd start
 ....
 
 Each file system that can be automatically mounted appears as a directory in [.filename]#/media/#.
 The directory is named after the file system label.
 If the label is missing, the directory is named after the device node.
 
 The file system is transparently mounted on the first access, and unmounted after a period of inactivity.
 Automounted drives can also be unmounted manually:
 
 [source,shell]
 ....
 # automount -fu
 ....
 
 This mechanism is typically used for memory cards and USB memory sticks.
 It can be used with any block device, including optical drives or iSCSILUNs.
 
 [[creating-cds]]
 == Creating and Using CD Media
 
 Compact Disc (CD) media provide a number of features that differentiate them from conventional disks.
 They are designed so that they can be read continuously without delays to move the head between tracks.
 While CD media do have tracks, these refer to a section of data to be read continuously, and not a physical property of the disk.
 The ISO 9660 file system was designed to deal with these differences.
 
 The FreeBSD Ports Collection provides several utilities for burning and duplicating audio and data CDs.
 This chapter demonstrates the use of several command line utilities.
 For CD burning software with a graphical utility, consider installing the package:sysutils/xcdroast[] or package:sysutils/k3b[] packages or ports.
 
 [[atapicam]]
 === Supported Devices
 
 The [.filename]#GENERIC# kernel provides support for SCSI, USB, and ATAPICD readers and burners.
 If a custom kernel is used, the options that need to be present in the kernel configuration file vary by the type of device.
 
 For a SCSI burner, make sure these options are present:
 
 [.programlisting]
 ....
 device scbus	# SCSI bus (required for ATA/SCSI)
 device da	# Direct Access (disks)
 device pass	# Passthrough device (direct ATA/SCSI access)
 device cd	# needed for CD and DVD burners
 ....
 
 For a USB burner, make sure these options are present:
 
 [.programlisting]
 ....
 device scbus	# SCSI bus (required for ATA/SCSI)
 device da	# Direct Access (disks)
 device pass	# Passthrough device (direct ATA/SCSI access)
 device cd	# needed for CD and DVD burners
 device uhci	# provides USB 1.x support
 device ohci	# provides USB 1.x support
 device ehci	# provides USB 2.0 support
 device xhci	# provides USB 3.0 support
 device usb	# USB Bus (required)
 device umass	# Disks/Mass storage - Requires scbus and da
 ....
 
 For an ATAPI burner, make sure these options are present:
 
 [.programlisting]
 ....
 device ata	# Legacy ATA/SATA controllers
 device scbus	# SCSI bus (required for ATA/SCSI)
 device pass	# Passthrough device (direct ATA/SCSI access)
 device cd	# needed for CD and DVD burners
 ....
 
 [NOTE]
 ====
 On FreeBSD versions prior to 10.x, this line is also needed in the kernel configuration file if the burner is an ATAPI device:
 
 [.programlisting]
 ....
 device atapicam
 ....
 
 Alternately, this driver can be loaded at boot time by adding the following line to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 atapicam_load="YES"
 ....
 
 This will require a reboot of the system as this driver can only be loaded at boot time.
 ====
 
 To verify that FreeBSD recognizes the device, run `dmesg` and look for an entry for the device.
 On systems prior to 10.x, the device name in the first line of the output will be [.filename]#acd0# instead of [.filename]#cd0#.
 
 [source,shell]
 ....
 % dmesg | grep cd
 cd0 at ahcich1 bus 0 scbus1 target 0 lun 0
 cd0: <HL-DT-ST DVDRAM GU70N LT20> Removable CD-ROM SCSI-0 device
 cd0: Serial Number M3OD3S34152
 cd0: 150.000MB/s transfers (SATA 1.x, UDMA6, ATAPI 12bytes, PIO 8192bytes)
 cd0: Attempt to query device size failed: NOT READY, Medium not present - tray closed
 ....
 
 [[cdrecord]]
 === Burning a CD
 
 In FreeBSD, `cdrecord` can be used to burn CDs.
 This command is installed with the package:sysutils/cdrtools[] package or port.
 
 While `cdrecord` has many options, basic usage is simple.
 Specify the name of the ISO file to burn and, if the system has multiple burner devices, specify the name of the device to use:
 
 [source,shell]
 ....
 # cdrecord dev=device imagefile.iso
 ....
 
 To determine the device name of the burner, use `-scanbus` which might produce results like this:
 
 [source,shell]
 ....
 # cdrecord -scanbus
 ProDVD-ProBD-Clone 3.00 (amd64-unknown-freebsd10.0) Copyright (C) 1995-2010 Jörg Schilling
 Using libscg version 'schily-0.9'
 scsibus0:
         0,0,0     0) 'SEAGATE ' 'ST39236LW       ' '0004' Disk
         0,1,0     1) 'SEAGATE ' 'ST39173W        ' '5958' Disk
         0,2,0     2) *
         0,3,0     3) 'iomega  ' 'jaz 1GB         ' 'J.86' Removable Disk
         0,4,0     4) 'NEC     ' 'CD-ROM DRIVE:466' '1.26' Removable CD-ROM
         0,5,0     5) *
         0,6,0     6) *
         0,7,0     7) *
 scsibus1:
         1,0,0   100) *
         1,1,0   101) *
         1,2,0   102) *
         1,3,0   103) *
         1,4,0   104) *
         1,5,0   105) 'YAMAHA  ' 'CRW4260         ' '1.0q' Removable CD-ROM
         1,6,0   106) 'ARTEC   ' 'AM12S           ' '1.06' Scanner
         1,7,0   107) *
 ....
 
 Locate the entry for the CD burner and use the three numbers separated by commas as the value for `dev`.
 In this case, the Yamaha burner device is `1,5,0`, so the appropriate input to specify that device is `dev=1,5,0`.
 Refer to the manual page for `cdrecord` for other ways to specify this value and for information on writing audio tracks and controlling the write speed.
 
 Alternately, run the following command to get the device address of the burner:
 
 [source,shell]
 ....
 # camcontrol devlist
 <MATSHITA CDRW/DVD UJDA740 1.00>   at scbus1 target 0 lun 0 (cd0,pass0)
 ....
 
 Use the numeric values for `scbus`, `target`, and `lun`.
 For this example, `1,0,0` is the device name to use.
 
 [[mkisofs]]
 === Writing Data to an ISO File System
 
 In order to produce a data CD, the data files that are going to make up the tracks on the CD must be prepared before they can be burned to the CD.
 In FreeBSD, package:sysutils/cdrtools[] installs `mkisofs`, which can be used to produce an ISO 9660 file system that is an image of a directory tree within a UNIX(R) file system.
 The simplest usage is to specify the name of the ISO file to create and the path to the files to place into the ISO 9660 file system:
 
 [source,shell]
 ....
 # mkisofs -o imagefile.iso /path/to/tree
 ....
 
 This command maps the file names in the specified path to names that fit the limitations of the standard ISO 9660 file system, and will exclude files that do not meet the standard for ISO file systems.
 
 A number of options are available to overcome the restrictions imposed by the standard.
 In particular, `-R` enables the Rock Ridge extensions common to UNIX(R) systems and `-J` enables Joliet extensions used by Microsoft(R) systems.
 
 For CDs that are going to be used only on FreeBSD systems, `-U` can be used to disable all filename restrictions.
 When used with `-R`, it produces a file system image that is identical to the specified FreeBSD tree, even if it violates the ISO 9660 standard.
 
 The last option of general use is `-b`.
 This is used to specify the location of a boot image for use in producing an "El Torito" bootable CD.
 This option takes an argument which is the path to a boot image from the top of the tree being written to the CD.
 By default, `mkisofs` creates an ISO image in "floppy disk emulation" mode, and thus expects the boot image to be exactly 1200, 1440 or 2880 KB in size. 
 Some boot loaders, like the one used by the FreeBSD distribution media, do not use emulation mode.
 In this case, `-no-emul-boot` should be used.
 So, if [.filename]#/tmp/myboot# holds a bootable FreeBSD system with the boot image in [.filename]#/tmp/myboot/boot/cdboot#, this command would produce [.filename]#/tmp/bootable.iso#:
 
 [source,shell]
 ....
 # mkisofs -R -no-emul-boot -b boot/cdboot -o /tmp/bootable.iso /tmp/myboot
 ....
 
 The resulting ISO image can be mounted as a memory disk with:
 
 [source,shell]
 ....
 # mdconfig -a -t vnode -f /tmp/bootable.iso -u 0
 # mount -t cd9660 /dev/md0 /mnt
 ....
 
 One can then verify that [.filename]#/mnt# and [.filename]#/tmp/myboot# are identical.
 
 There are many other options available for `mkisofs` to fine-tune its behavior.
 Refer to man:mkisofs[8] for details.
 
 [NOTE]
 ====
 It is possible to copy a data CD to an image file that is functionally equivalent to the image file created with `mkisofs`.
 To do so, use [.filename]#dd# with the device name as the input file and the name of the ISO to create as the output file:
 
 [source,shell]
 ....
 # dd if=/dev/cd0 of=file.iso bs=2048
 ....
 
 The resulting image file can be burned to CD as described in <<cdrecord>>.
 ====
 
 [[mounting-cd]]
 === Using Data CDs
 
 Once an ISO has been burned to a CD, it can be mounted by specifying the file system type, the name of the device containing the CD, and an existing mount point:
 
 [source,shell]
 ....
 # mount -t cd9660 /dev/cd0 /mnt
 ....
 
 Since `mount` assumes that a file system is of type `ufs`, an `Incorrect super block` error will occur if `-t cd9660` is not included when mounting a data CD.
 
 While any data CD can be mounted this way, disks with certain ISO 9660 extensions might behave oddly.
 For example, Joliet disks store all filenames in two-byte Unicode characters.
 If some non-English characters show up as question marks, specify the local charset with `-C`.
 For more information, refer to man:mount_cd9660[8].
 
 [NOTE]
 ====
 In order to do this character conversion with the help of `-C`, the kernel requires the [.filename]#cd9660_iconv.ko# module to be loaded.
 This can be done either by adding this line to [.filename]#loader.conf#:
 
 [.programlisting]
 ....
 cd9660_iconv_load="YES"
 ....
 
 and then rebooting the machine, or by directly loading the module with `kldload`.
 ====
 
 Occasionally, `Device not configured` will be displayed when trying to mount a data CD.
 This usually means that the CD drive has not detected a disk in the tray, or that the drive is not visible on the bus.
 It can take a couple of seconds for a CD drive to detect media, so be patient.
 
 Sometimes, a SCSICD drive may be missed because it did not have enough time to answer the bus reset.
 To resolve this, a custom kernel can be created which increases the default SCSI delay.
 Add the following option to the custom kernel configuration file and rebuild the kernel using the instructions in crossref:kernelconfig[kernelconfig-building,“Building and Installing a Custom Kernel”]:
 
 [.programlisting]
 ....
 options SCSI_DELAY=15000
 ....
 
 This tells the SCSI bus to pause 15 seconds during boot, to give the CD drive every possible chance to answer the bus reset.
 
 [NOTE]
 ====
 It is possible to burn a file directly to CD, without creating an ISO 9660 file system.
 This is known as burning a raw data CD and some people do this for backup purposes.
 
 This type of disk can not be mounted as a normal data CD.
 In order to retrieve the data burned to such a CD, the data must be read from the raw device node.
 For example, this command will extract a compressed tar file located on the second CD device into the current working directory:
 
 [source,shell]
 ....
 # tar xzvf /dev/cd1
 ....
 
 In order to mount a data CD, the data must be written using `mkisofs`.
 ====
 
 [[duplicating-audiocds]]
 === Duplicating Audio CDs
 
 To duplicate an audio CD, extract the audio data from the CD to a series of files, then write these files to a blank CD.
 
 <<using-cdrecord>> describes how to duplicate and burn an audio CD.
 If the FreeBSD version is less than 10.0 and the device is ATAPI, the `atapicam` module must be first loaded using the instructions in <<atapicam>>.
 
 [[using-cdrecord]]
 [.procedure]
 .Procedure: Duplicating an Audio CD
 . The package:sysutils/cdrtools[] package or port installs `cdda2wav`. This command can be used to extract all of the audio tracks, with each track written to a separate WAV file in the current working directory:
 +
 [source,shell]
 ....
 % cdda2wav -vall -B -Owav
 ....
-+ 
++
 A device name does not need to be specified if there is only one CD device on the system.
 Refer to the `cdda2wav` manual page for instructions on how to specify a device and to learn more about the other options available for this command.
 . Use `cdrecord` to write the [.filename]#.wav# files:
 +
 [source,shell]
 ....
 % cdrecord -v dev=2,0 -dao -useinfo  *.wav
 ....
-+ 
++
 Make sure that _2,0_ is set appropriately, as described in <<cdrecord>>.
 
 [[creating-dvds]]
 == Creating and Using DVD Media
 
 Compared to the CD, the DVD is the next generation of optical media storage technology.
 The DVD can hold more data than any CD and is the standard for video publishing.
 
 Five physical recordable formats can be defined for a recordable DVD:
 
 * DVD-R: This was the first DVD recordable format available. The DVD-R standard is defined by the http://www.dvdforum.org/forum.shtml[DVD Forum]. This format is write once.
 * DVD-RW: This is the rewritable version of the DVD-R standard. A DVD-RW can be rewritten about 1000 times.
 * DVD-RAM: This is a rewritable format which can be seen as a removable hard drive. However, this media is not compatible with most DVD-ROM drives and DVD-Video players as only a few DVD writers support the DVD-RAM format. Refer to <<creating-dvd-ram>> for more information on DVD-RAM use.
 * DVD+RW: This is a rewritable format defined by the https://en.wikipedia.org/wiki/DVD%2BRW_Alliance[DVD+RW Alliance]. A DVD+RW can be rewritten about 1000 times.
 * DVD+R: This format is the write once variation of the DVD+RW format.
 
 A single layer recordable DVD can hold up to 4,700,000,000 bytes which is actually 4.38 GB or 4485 MB as 1 kilobyte is 1024 bytes.
 
 [NOTE]
 ====
 A distinction must be made between the physical media and the application.
 For example, a DVD-Video is a specific file layout that can be written on any recordable DVD physical media such as DVD-R, DVD+R, or DVD-RW.
 Before choosing the type of media, ensure that both the burner and the DVD-Video player are compatible with the media under consideration.
 ====
 
 === Configuration
 
 To perform DVD recording, use man:growisofs[1].
 This command is part of the package:sysutils/dvd+rw-tools[] utilities which support all DVD media types.
 
 These tools use the SCSI subsystem to access the devices, therefore <<atapicam,ATAPI/CAM support>> must be loaded or statically compiled into the kernel.
 This support is not needed if the burner uses the USB interface.
 Refer to <<usb-disks>> for more details on USB device configuration.
 
 DMA access must also be enabled for ATAPI devices, by adding the following line to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 hw.ata.atapi_dma="1"
 ....
 
 Before attempting to use dvd+rw-tools, consult the http://fy.chalmers.se/~appro/linux/DVD+RW/hcn.html[Hardware Compatibility Notes].
 
 [NOTE]
 ====
 For a graphical user interface, consider using package:sysutils/k3b[] which provides a user friendly interface to man:growisofs[1] and many other burning tools.
 ====
 
 === Burning Data DVDs
 
 Since man:growisofs[1] is a front-end to <<mkisofs,mkisofs>>, it will invoke man:mkisofs[8] to create the file system layout and perform the write on the DVD.
 This means that an image of the data does not need to be created before the burning process.
 
 To burn to a DVD+R or a DVD-R the data in [.filename]#/path/to/data#, use the following command:
 
 [source,shell]
 ....
 # growisofs -dvd-compat -Z /dev/cd0 -J -R /path/to/data
 ....
 
 In this example, `-J -R` is passed to man:mkisofs[8] to create an ISO 9660 file system with Joliet and Rock Ridge extensions.
 Refer to man:mkisofs[8] for more details.
 
 For the initial session recording, `-Z` is used for both single and multiple sessions.
 Replace _/dev/cd0_, with the name of the DVD device.
 Using `-dvd-compat` indicates that the disk will be closed and that the recording will be unappendable.
 This should also provide better media compatibility with DVD-ROM drives.
 
 To burn a pre-mastered image, such as _imagefile.iso_, use:
 
 [source,shell]
 ....
 # growisofs -dvd-compat -Z /dev/cd0=imagefile.iso
 ....
 
 The write speed should be detected and automatically set according to the media and the drive being used.
 To force the write speed, use `-speed=`. Refer to man:growisofs[1] for example usage.
 
 [NOTE]
 ====
 In order to support working files larger than 4.38GB, an UDF/ISO-9660 hybrid file system must be created by passing `-udf -iso-level 3` to man:mkisofs[8] and all related programs, such as man:growisofs[1].
 This is required only when creating an ISO image file or when writing files directly to a disk.
 Since a disk created this way must be mounted as an UDF file system with man:mount_udf[8], it will be usable only on an UDF aware operating system. 
 Otherwise it will look as if it contains corrupted files.
 
 To create this type of ISO file:
 
 [source,shell]
 ....
 % mkisofs -R -J -udf -iso-level 3 -o imagefile.iso /path/to/data
 ....
 
 To burn files directly to a disk:
 
 [source,shell]
 ....
 # growisofs -dvd-compat -udf -iso-level 3 -Z /dev/cd0 -J -R /path/to/data
 ....
 
 When an ISO image already contains large files, no additional options are required for man:growisofs[1] to burn that image on a disk.
 
 Be sure to use an up-to-date version of package:sysutils/cdrtools[], which contains man:mkisofs[8], as an older version may not contain large files support.
 If the latest version does not work, install package:sysutils/cdrtools-devel[] and read its man:mkisofs[8].
 ====
 
 === Burning a DVD-Video
 
 A DVD-Video is a specific file layout based on the ISO 9660 and micro-UDF (M-UDF) specifications.
 Since DVD-Video presents a specific data structure hierarchy, a particular program such as package:multimedia/dvdauthor[] is needed to author the DVD.
 
 If an image of the DVD-Video file system already exists, it can be burned in the same way as any other image.
 If `dvdauthor` was used to make the DVD and the result is in [.filename]#/path/to/video#, the following command should be used to burn the DVD-Video:
 
 [source,shell]
 ....
 # growisofs -Z /dev/cd0 -dvd-video /path/to/video
 ....
 
 `-dvd-video` is passed to man:mkisofs[8] to instruct it to create a DVD-Video file system layout.
 This option implies the `-dvd-compat` man:growisofs[1] option.
 
 === Using a DVD+RW
 
 Unlike CD-RW, a virgin DVD+RW needs to be formatted before first use.
 It is _recommended_ to let man:growisofs[1] take care of this automatically whenever appropriate.
 However, it is possible to use `dvd+rw-format` to format the DVD+RW:
 
 [source,shell]
 ....
 # dvd+rw-format /dev/cd0
 ....
 
 Only perform this operation once and keep in mind that only virgin DVD+RW medias need to be formatted.
 Once formatted, the DVD+RW can be burned as usual.
 
 To burn a totally new file system and not just append some data onto a DVD+RW, the media does not need to be blanked first.
 Instead, write over the previous recording like this:
 
 [source,shell]
 ....
 # growisofs -Z /dev/cd0 -J -R /path/to/newdata
 ....
 
 The DVD+RW format supports appending data to a previous recording.
 This operation consists of merging a new session to the existing one as it is not considered to be multi-session writing.
 man:growisofs[1] will _grow_ the ISO 9660 file system present on the media.
 
 For example, to append data to a DVD+RW, use the following:
 
 [source,shell]
 ....
 # growisofs -M /dev/cd0 -J -R /path/to/nextdata
 ....
 
 The same man:mkisofs[8] options used to burn the initial session should be used during next writes.
 
 [NOTE]
 ====
 Use `-dvd-compat` for better media compatibility with DVD-ROM drives.
 When using DVD+RW, this option will not prevent the addition of data.
 ====
 
 To blank the media, use:
 
 [source,shell]
 ....
 # growisofs -Z /dev/cd0=/dev/zero
 ....
 
 === Using a DVD-RW
 
 A DVD-RW accepts two disc formats: incremental sequential and restricted overwrite.
 By default, DVD-RW discs are in sequential format.
 
 A virgin DVD-RW can be directly written without being formatted.
 However, a non-virgin DVD-RW in sequential format needs to be blanked before writing a new initial session.
 
 To blank a DVD-RW in sequential mode:
 
 [source,shell]
 ....
 # dvd+rw-format -blank=full /dev/cd0
 ....
 
 [NOTE]
 ====
 A full blanking using `-blank=full` will take about one hour on a 1x media.
 A fast blanking can be performed using `-blank`, if the DVD-RW will be recorded in Disk-At-Once (DAO) mode.
 To burn the DVD-RW in DAO mode, use the command:
 
 [source,shell]
 ....
 # growisofs -use-the-force-luke=dao -Z /dev/cd0=imagefile.iso
 ....
 
 Since man:growisofs[1] automatically attempts to detect fast blanked media and engage DAO write, `-use-the-force-luke=dao` should not be required.
 
 One should instead use restricted overwrite mode with any DVD-RW as this format is more flexible than the default of incremental sequential.
 ====
 
 To write data on a sequential DVD-RW, use the same instructions as for the other DVD formats:
 
 [source,shell]
 ....
 # growisofs -Z /dev/cd0 -J -R /path/to/data
 ....
 
 To append some data to a previous recording, use `-M` with man:growisofs[1].
 However, if data is appended on a DVD-RW in incremental sequential mode, a new session will be created on the disc and the result will be a multi-session disc.
 
 A DVD-RW in restricted overwrite format does not need to be blanked before a new initial session.
 Instead, overwrite the disc with `-Z`.
 It is also possible to grow an existing ISO 9660 file system written on the disc with `-M`.
 The result will be a one-session DVD.
 
 To put a DVD-RW in restricted overwrite format, the following command must be used:
 
 [source,shell]
 ....
 # dvd+rw-format /dev/cd0
 ....
 
 To change back to sequential format, use:
 
 [source,shell]
 ....
 # dvd+rw-format -blank=full /dev/cd0
 ....
 
 === Multi-Session
 
 Few DVD-ROM drives support multi-session DVDs and most of the time only read the first session.
 DVD+R, DVD-R and DVD-RW in sequential format can accept multiple sessions.
 The notion of multiple sessions does not exist for the DVD+RW and the DVD-RW restricted overwrite formats.
 
 Using the following command after an initial non-closed session on a DVD+R, DVD-R, or DVD-RW in sequential format, will add a new session to the disc:
 
 [source,shell]
 ....
 # growisofs -M /dev/cd0 -J -R /path/to/nextdata
 ....
 
 Using this command with a DVD+RW or a DVD-RW in restricted overwrite mode will append data while merging the new session to the existing one.
 The result will be a single-session disc.
 Use this method to add data after an initial write on these types of media.
 
 [NOTE]
 ====
 Since some space on the media is used between each session to mark the end and start of sessions, one should add sessions with a large amount of data to optimize media space.
 The number of sessions is limited to 154 for a DVD+R, about 2000 for a DVD-R, and 127 for a DVD+R Double Layer.
 ====
 
 === For More Information
 
 To obtain more information about a DVD, use `dvd+rw-mediainfo _/dev/cd0_` while the disc in the specified drive.
 
 More information about dvd+rw-tools can be found in man:growisofs[1], on the http://fy.chalmers.se/~appro/linux/DVD+RW/[dvd+rw-tools web site], and in the http://lists.debian.org/cdwrite/[cdwrite mailing list] archives.
 
 [NOTE]
 ====
 When creating a problem report related to the use of dvd+rw-tools, always include the output of `dvd+rw-mediainfo`.
 ====
 
 [[creating-dvd-ram]]
 === Using a DVD-RAM
 
 DVD-RAM writers can use either a SCSI or ATAPI interface.
 For ATAPI devices, DMA access has to be enabled by adding the following line to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 hw.ata.atapi_dma="1"
 ....
 
 A DVD-RAM can be seen as a removable hard drive.
 Like any other hard drive, the DVD-RAM must be formatted before it can be used.
 In this example, the whole disk space will be formatted with a standard UFS2 file system:
 
 [source,shell]
 ....
 # dd if=/dev/zero of=/dev/acd0 bs=2k count=1
 # bsdlabel -Bw acd0
 # newfs /dev/acd0
 ....
 
 The DVD device, [.filename]#acd0#, must be changed according to the configuration.
 
 Once the DVD-RAM has been formatted, it can be mounted as a normal hard drive:
 
 [source,shell]
 ....
 # mount /dev/acd0 /mnt
 ....
 
 Once mounted, the DVD-RAM will be both readable and writeable.
 
 [[floppies]]
 == Creating and Using Floppy Disks
 
 This section explains how to format a 3.5 inch floppy disk in FreeBSD.
 
 [.procedure]
 ====
 *Procedure: Steps to Format a Floppy*
 
 A floppy disk needs to be low-level formatted before it can be used.
 This is usually done by the vendor, but formatting is a good way to check media integrity.
 To low-level format the floppy disk on FreeBSD, use man:fdformat[1].
 When using this utility, make note of any error messages, as these can help determine if the disk is good or bad.
 
 . To format the floppy, insert a new 3.5 inch floppy disk into the first floppy drive and issue:
 +
 [source,shell]
 ....
 # /usr/sbin/fdformat -f 1440 /dev/fd0
 ....
 +
 . After low-level formatting the disk, create a disk label as it is needed by the system to determine the size of the disk and its geometry. The supported geometry values are listed in [.filename]#/etc/disktab#.
 +
 To write the disk label, use man:bsdlabel[8]:
 +
 [source,shell]
 ....
 # /sbin/bsdlabel -B -w /dev/fd0 fd1440
 ....
 +
 . The floppy is now ready to be high-level formatted with a file system. The floppy's file system can be either UFS or FAT, where FAT is generally a better choice for floppies.
 +
 To format the floppy with FAT, issue:
 +
 [source,shell]
 ....
 # /sbin/newfs_msdos /dev/fd0
 ....
 ====
 
 The disk is now ready for use.
 To use the floppy, mount it with man:mount_msdosfs[8].
 One can also install and use package:emulators/mtools[] from the Ports Collection.
 
 [[using-ntfs]]
 == Using NTFS Disks
 
 This section explains how to mount NTFS disks in FreeBSD.
 
 NTFS (New Technology File System) is a proprietary journaling file system developed by Microsoft(R).
 It has been the default file system in Microsoft Windows(R) for many years.
 FreeBSD can mount NTFS volumes using a FUSE file system.
 These file systems are implemented as user space programs which interact with the man:fusefs[5] kernel module via a well defined interface.
 
 [.procedure]
 ====
 *Procedure: Steps to Mount a NTFS Disk*
 
 . Before using a FUSE file system we need to load the man:fusefs[5] kernel
 module:
 +
 [source,shell]
 ....
 # kldload fusefs
 ....
 +
 Use man:sysrc[8] to load the module at startup:
 +
 [source,shell]
 ....
 # sysrc kld_list+=fusefs
 ....
 
 . Install the actual NTFS file system from packages as in the example (see crossref:ports[pkgng-intro,Using pkg for Binary Package Management]) or from ports (see crossref:ports[ports-using,Using the Ports Collection]):
 +
 [source,shell]
 ....
 # pkg install fusefs-ntfs
 ....
 
 . Last we need to create a directory where the file system will be mounted:
 +
 [source,shell]
 ....
 # mkdir /mnt/usb
 ....
 
 . Suppose a USB disk is plugged in.  The disk partition information can be viewed with man:gpart[8]:
 +
 [source,shell]
 ....
 # gpart show da0
 =>	  63  1953525105  da0 MBR   (932G)
 	  63  1953525105    1 ntfs  (932G)
 ....
 
 . We can mount the disk using the following command:
 +
 [source,shell]
 ....
 # ntfs-3g /dev/da0s1 /mnt/usb/
 ....
 The disk is now ready to use.
 +
 . Additionally, an entry can be added to /etc/fstab:
 +
 [.programlisting]
 ....
 /dev/da0s1  /mnt/usb	ntfs mountprog=/usr/local/bin/ntfs-3g,noauto,rw  0 0
 ....
 +
 Now the disk can be now mounted with:
 +
 [source,shell]
 ....
 # mount /mnt/usb
 ....
 
 . The disk can be unmounted with:
 +
 [source,shell]
 ....
 # umount /mnt/usb/
 ....
 ====
 
 [[backup-basics]]
 == Backup Basics
 
 Implementing a backup plan is essential in order to have the ability to recover from disk failure, accidental file deletion, random file corruption, or complete machine destruction, including destruction of on-site backups.
 
 The backup type and schedule will vary, depending upon the importance of the data, the granularity needed for file restores, and the amount of acceptable downtime.
 Some possible backup techniques include:
 
 * Archives of the whole system, backed up onto permanent, off-site media. This provides protection against all of the problems listed above, but is slow and inconvenient to restore from, especially for non-privileged users.
 * File system snapshots, which are useful for restoring deleted files or previous versions of files.
 * Copies of whole file systems or disks which are synchronized with another system on the network using a scheduled package:net/rsync[].
 * Hardware or software RAID, which minimizes or avoids downtime when a disk fails.
 
 Typically, a mix of backup techniques is used.
 For example, one could create a schedule to automate a weekly, full system backup that is stored off-site and to supplement this backup with hourly ZFS snapshots.
 In addition, one could make a manual backup of individual directories or files before making file edits or deletions.
 
 This section describes some of the utilities which can be used to create and manage backups on a FreeBSD system.
 
 === File System Backups
 
 The traditional UNIX(R) programs for backing up a file system are man:dump[8], which creates the backup, and man:restore[8], which restores the backup.
 These utilities work at the disk block level, below the abstractions of the files, links, and directories that are created by file systems.
 Unlike other backup software, `dump` backs up an entire file system and is unable to backup only part of a file system or a directory tree that spans multiple file systems.
 Instead of writing files and directories, `dump` writes the raw data blocks that comprise files and directories.
 
 [NOTE]
 ====
 If `dump` is used on the root directory, it will not back up [.filename]#/home#, [.filename]#/usr# or many other directories since these are typically mount points for other file systems or symbolic links into those file systems.
 ====
 
 When used to restore data, `restore` stores temporary files in [.filename]#/tmp/# by default.
 When using a recovery disk with a small [.filename]#/tmp#, set `TMPDIR` to a directory with more free space in order for the restore to succeed.
 
 When using `dump`, be aware that some quirks remain from its early days in Version 6 of AT&T UNIX(R),circa 1975.
 The default parameters assume a backup to a 9-track tape, rather than to another type of media or to the high-density tapes available today.
 These defaults must be overridden on the command line.
 
 It is possible to backup a file system across the network to a another system or to a tape drive attached to another computer.
 While the man:rdump[8] and man:rrestore[8] utilities can be used for this purpose, they are not considered to be secure.
 
 Instead, one can use `dump` and `restore` in a more secure fashion over an SSH connection.
 This example creates a full, compressed backup of [.filename]#/usr# and sends the backup file to the specified host over a SSH connection.
 
 .Using `dump` over ssh
 [example]
 ====
 [source,shell]
 ....
 # /sbin/dump -0uan -f - /usr | gzip -2 | ssh -c blowfish \
           targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz
 ....
 ====
 
 This example sets `RSH` in order to write the backup to a tape drive on a remote system over a SSH connection:
 
 .Using `dump` over ssh with `RSH` Set
 [example]
 ====
 [source,shell]
 ....
 # env RSH=/usr/bin/ssh /sbin/dump -0uan -f targetuser@targetmachine.example.com:/dev/sa0 /usr
 ....
 ====
 
 === Directory Backups
 
 Several built-in utilities are available for backing up and restoring specified files and directories as needed.
 
 A good choice for making a backup of all of the files in a directory is man:tar[1].
 This utility dates back to Version 6 of AT&T UNIX(R) and by default assumes a recursive backup to a local tape device.
 Switches can be used to instead specify the name of a backup file.
 
 This example creates a compressed backup of the current directory and saves it to [.filename]#/tmp/mybackup.tgz#.
 When creating a backup file, make sure that the backup is not saved to the same directory that is being backed up.
 
 .Backing Up the Current Directory with `tar`
 [example]
 ====
 [source,shell]
 ....
 # tar czvf /tmp/mybackup.tgz .
 ....
 ====
 
 To restore the entire backup, `cd` into the directory to restore into and specify the name of the backup.
 Note that this will overwrite any newer versions of files in the restore directory. 
 When in doubt, restore to a temporary directory or specify the name of the file within the backup to restore.
 
 .Restoring Up the Current Directory with `tar`
 [example]
 ====
 [source,shell]
 ....
 # tar xzvf /tmp/mybackup.tgz
 ....
 ====
 
 There are dozens of available switches which are described in man:tar[1].
 This utility also supports the use of exclude patterns to specify which files should not be included when backing up the specified directory or restoring files from a backup.
 
 To create a backup using a specified list of files and directories, man:cpio[1] is a good choice.
 Unlike `tar`, `cpio` does not know how to walk the directory tree and it must be provided the list of files to backup.
 
 For example, a list of files can be created using `ls` or `find`.
 This example creates a recursive listing of the current directory which is then piped to `cpio` in order to create an output backup file named [.filename]#/tmp/mybackup.cpio#.
 
 .Using `ls` and `cpio` to Make a Recursive Backup of the Current Directory
 [example]
 ====
 [source,shell]
 ....
 # ls -R | cpio -ovF /tmp/mybackup.cpio
 ....
 ====
 
 A backup utility which tries to bridge the features provided by `tar` and `cpio` is man:pax[1].
 Over the years, the various versions of `tar` and `cpio` became slightly incompatible.
 POSIX(R) created `pax` which attempts to read and write many of the various `cpio` and `tar` formats, plus new formats of its own.
 
 The `pax` equivalent to the previous examples would be:
 
 .Backing Up the Current Directory with `pax`
 [example]
 ====
 [source,shell]
 ....
 # pax -wf /tmp/mybackup.pax .
 ....
 ====
 
 [[backups-tapebackups]]
 === Using Data Tapes for Backups
 
 While tape technology has continued to evolve, modern backup systems tend to combine off-site backups with local removable media.
 FreeBSD supports any tape drive that uses SCSI, such as LTO or DAT.
 There is limited support for SATA and USB tape drives.
 
 For SCSI tape devices, FreeBSD uses the man:sa[4] driver and the [.filename]#/dev/sa0#, [.filename]#/dev/nsa0#, and [.filename]#/dev/esa0# devices. 
 The physical device name is [.filename]#/dev/sa0#. When [.filename]#/dev/nsa0# is used, the backup application will not rewind the tape after writing a file, which allows writing more than one file to a tape.
 Using [.filename]#/dev/esa0# ejects the tape after the device is closed.
 
 In FreeBSD, `mt` is used to control operations of the tape drive, such as seeking through files on a tape or writing tape control marks to the tape.
 For example, the first three files on a tape can be preserved by skipping past them before writing a new file:
 
 [source,shell]
 ....
 # mt -f /dev/nsa0 fsf 3
 ....
 
 This utility supports many operations. Refer to man:mt[1] for details.
 
 To write a single file to tape using `tar`, specify the name of the tape device and the file to backup:
 
 [source,shell]
 ....
 # tar cvf /dev/sa0 file
 ....
 
 To recover files from a `tar` archive on tape into the current directory:
 
 [source,shell]
 ....
 # tar xvf /dev/sa0
 ....
 
 To backup a UFS file system, use `dump`.
 This examples backs up [.filename]#/usr# without rewinding the tape when finished:
 
 [source,shell]
 ....
 # dump -0aL -b64 -f /dev/nsa0 /usr
 ....
 
 To interactively restore files from a `dump` file on tape into the current directory:
 
 [source,shell]
 ....
 # restore -i -f /dev/nsa0
 ....
 
 [[backups-programs-amanda]]
 === Third-Party Backup Utilities
 
 The FreeBSD Ports Collection provides many third-party utilities which can be used to schedule the creation of backups, simplify tape backup, and make backups easier and more convenient.
 Many of these applications are client/server based and can be used to automate the backups of a single system or all of the computers in a network.
 
 Popular utilities include Amanda, Bacula, rsync, and duplicity.
 
 === Emergency Recovery
 
 In addition to regular backups, it is recommended to perform the following steps as part of an emergency preparedness plan.
 
 Create a print copy of the output of the following commands:
 
 * `gpart show`
 * `more /etc/fstab`
 * `dmesg`
 
 Store this printout and a copy of the installation media in a secure location.
 Should an emergency restore be needed, boot into the installation media and select `Live CD` to access a rescue shell.
 This rescue mode can be used to view the current state of the system, and if needed, to reformat disks and restore data from backups.
 
 [NOTE]
 ====
 The installation media for FreeBSD/i386 {rel112-current}-RELEASE does not include a rescue shell.
 For this version, instead download and burn a Livefs CD image from link:ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/ISO-IMAGES/{rel112-current}/FreeBSD-{rel112-current}-RELEASE-i386-livefs.iso[ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/ISO-IMAGES/{rel112-current}/FreeBSD-{rel112-current}-RELEASE-i386-livefs.iso].
 ====
 
 Next, test the rescue shell and the backups.
 Make notes of the procedure.
 Store these notes with the media, the printouts, and the backups.
 These notes may prevent the inadvertent destruction of the backups while under the stress of performing an emergency recovery.
 
 For an added measure of security, store the latest backup at a remote location which is physically separated from the computers and disk drives by a significant distance.
 
 [[disks-virtual]]
 == Memory Disks
 
 In addition to physical disks, FreeBSD also supports the creation and use of memory disks.
 One possible use for a memory disk is to access the contents of an ISO file system without the overhead of first burning it to a CD or DVD, then mounting the CD/DVD media.
 
 In FreeBSD, the man:md[4] driver is used to provide support for memory disks.
 The [.filename]#GENERIC# kernel includes this driver.
 When using a custom kernel configuration file, ensure it includes this line:
 
 [.programlisting]
 ....
 device md
 ....
 
 [[disks-mdconfig]]
 === Attaching and Detaching Existing Images
 
 To mount an existing file system image, use `mdconfig` to specify the name of the ISO file and a free unit number.
 Then, refer to that unit number to mount it on an existing mount point.
 Once mounted, the files in the ISO will appear in the mount point.
 This example attaches _diskimage.iso_ to the memory device [.filename]#/dev/md0# then mounts that memory device on [.filename]#/mnt#:
 
 [source,shell]
 ....
 # mdconfig -f diskimage.iso -u 0
 # mount -t cd9660 /dev/md0 /mnt
 ....
 
 Notice that `-t cd9660` was used to mount an ISO format.
 If a unit number is not specified with `-u`, `mdconfig` will automatically allocate an unused memory device and output the name of the allocated unit, such as [.filename]#md4#.
 Refer to man:mdconfig[8] for more details about this command and its options.
 
 When a memory disk is no longer in use, its resources should be released back to the system.
 First, unmount the file system, then use `mdconfig` to detach the disk from the system and release its resources.
 To continue this example:
 
 [source,shell]
 ....
 # umount /mnt
 # mdconfig -d -u 0
 ....
 
 To determine if any memory disks are still attached to the system, type `mdconfig -l`.
 
 [[disks-md-freebsd5]]
 === Creating a File- or Memory-Backed Memory Disk
 
 FreeBSD also supports memory disks where the storage to use is allocated from either a hard disk or an area of memory.
 The first method is commonly referred to as a file-backed file system and the second method as a memory-backed file system.
 Both types can be created using `mdconfig`.
 
 To create a new memory-backed file system, specify a type of `swap` and the size of the memory disk to create.
 Then, format the memory disk with a file system and mount as usual.
 This example creates a 5M memory disk on unit `1`.
 That memory disk is then formatted with the UFS file system before it is mounted:
 
 [source,shell]
 ....
 # mdconfig -a -t swap -s 5m -u 1
 # newfs -U md1
 /dev/md1: 5.0MB (10240 sectors) block size 16384, fragment size 2048
         using 4 cylinder groups of 1.27MB, 81 blks, 192 inodes.
         with soft updates
 super-block backups (for fsck -b #) at:
  160, 2752, 5344, 7936
 # mount /dev/md1 /mnt
 # df /mnt
 Filesystem 1K-blocks Used Avail Capacity  Mounted on
 /dev/md1        4718    4  4338     0%    /mnt
 ....
 
 To create a new file-backed memory disk, first allocate an area of disk to use.
 This example creates an empty 5MB file named [.filename]#newimage#:
 
 [source,shell]
 ....
 # dd if=/dev/zero of=newimage bs=1k count=5k
 5120+0 records in
 5120+0 records out
 ....
 
 Next, attach that file to a memory disk, label the memory disk and format it with the UFS file system, mount the memory disk, and verify the size of the file-backed disk:
 
 [source,shell]
 ....
 # mdconfig -f newimage -u 0
 # bsdlabel -w md0 auto
 # newfs -U md0a
 /dev/md0a: 5.0MB (10224 sectors) block size 16384, fragment size 2048
         using 4 cylinder groups of 1.25MB, 80 blks, 192 inodes.
 super-block backups (for fsck -b #) at:
  160, 2720, 5280, 7840
 # mount /dev/md0a /mnt
 # df /mnt
 Filesystem 1K-blocks Used Avail Capacity  Mounted on
 /dev/md0a       4710    4  4330     0%    /mnt
 ....
 
 It takes several commands to create a file- or memory-backed file system using `mdconfig`.
 FreeBSD also comes with `mdmfs` which automatically configures a memory disk, formats it with the UFS file system, and mounts it.
 For example, after creating _newimage_ with `dd`, this one command is equivalent to running the `bsdlabel`, `newfs`, and `mount` commands shown above:
 
 [source,shell]
 ....
 # mdmfs -F newimage -s 5m md0 /mnt
 ....
 
 To instead create a new memory-based memory disk with `mdmfs`, use this one command:
 
 [source,shell]
 ....
 # mdmfs -s 5m md1 /mnt
 ....
 
 If the unit number is not specified, `mdmfs` will automatically select an unused memory device.
 For more details about `mdmfs`, refer to man:mdmfs[8].
 
 [[snapshots]]
 == File System Snapshots
 
 FreeBSD offers a feature in conjunction with crossref:config[soft-updates,Soft Updates]: file system snapshots.
 
 UFS snapshots allow a user to create images of specified file systems, and treat them as a file.
 Snapshot files must be created in the file system that the action is performed on, and a user may create no more than 20 snapshots per file system. 
 Active snapshots are recorded in the superblock so they are persistent across unmount and remount operations along with system reboots.
 When a snapshot is no longer required, it can be removed using man:rm[1].
 While snapshots may be removed in any order, all the used space may not be acquired because another snapshot will possibly claim some of the released blocks.
 
 The un-alterable `snapshot` file flag is set by man:mksnap_ffs[8] after initial creation of a snapshot file.
 man:unlink[1] makes an exception for snapshot files since it allows them to be removed.
 
 Snapshots are created using man:mount[8].
 To place a snapshot of [.filename]#/var# in the file [.filename]#/var/snapshot/snap#, use the following command:
 
 [source,shell]
 ....
 # mount -u -o snapshot /var/snapshot/snap /var
 ....
 
 Alternatively, use man:mksnap_ffs[8] to create the snapshot:
 
 [source,shell]
 ....
 # mksnap_ffs /var /var/snapshot/snap
 ....
 
 One can find snapshot files on a file system, such as [.filename]#/var#, using man:find[1]:
 
 [source,shell]
 ....
 # find /var -flags snapshot
 ....
 
 Once a snapshot has been created, it has several uses:
 
 * Some administrators will use a snapshot file for backup purposes, because the snapshot can be transferred to CDs or tape.
 * The file system integrity checker, man:fsck[8], may be run on the snapshot. Assuming that the file system was clean when it was mounted, this should always provide a clean and unchanging result.
 * Running man:dump[8] on the snapshot will produce a dump file that is consistent with the file system and the timestamp of the snapshot. man:dump[8] can also take a snapshot, create a dump image, and then remove the snapshot in one command by using `-L`.
 * The snapshot can be mounted as a frozen image of the file system. To man:mount[8] the snapshot [.filename]#/var/snapshot/snap# run:
 +
 [source,shell]
 ....
 # mdconfig -a -t vnode -o readonly -f /var/snapshot/snap -u 4
 # mount -r /dev/md4 /mnt
 ....
 
 The frozen [.filename]#/var# is now available through [.filename]#/mnt#.
 Everything will initially be in the same state it was during the snapshot creation time.
 The only exception is that any earlier snapshots will appear as zero length files.
 To unmount the snapshot, use:
 
 [source,shell]
 ....
 # umount /mnt
 # mdconfig -d -u 4
 ....
 
 For more information about `softupdates` and file system snapshots, including technical papers, visit Marshall Kirk McKusick's website at http://www.mckusick.com/[http://www.mckusick.com/].
 
 [[quotas]]
 == Disk Quotas
 
 Disk quotas can be used to limit the amount of disk space or the number of files a user or members of a group may allocate on a per-file system basis. 
 This prevents one user or group of users from consuming all of the available disk space.
 
 This section describes how to configure disk quotas for the UFS file system.
 To configure quotas on the ZFS file system, refer to crossref:zfs[zfs-zfs-quota,"Dataset, User, and Group Quotas"]
 
 === Enabling Disk Quotas
 
 To determine if the FreeBSD kernel provides support for disk quotas:
 
 [source,shell]
 ....
 % sysctl kern.features.ufs_quota
 kern.features.ufs_quota: 1
 ....
 
 In this example, the `1` indicates quota support.
 If the value is instead `0`, add the following line to a custom kernel configuration file and rebuild the kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel]:
 
 [.programlisting]
 ....
 options QUOTA
 ....
 
 Next, enable disk quotas in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 quota_enable="YES"
 ....
 
 Normally on bootup, the quota integrity of each file system is checked by man:quotacheck[8].
 This program insures that the data in the quota database properly reflects the data on the file system.
 This is a time consuming process that will significantly affect the time the system takes to boot.
 To skip this step, add this variable to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 check_quotas="NO"
 ....
 
 Finally, edit [.filename]#/etc/fstab# to enable disk quotas on a per-file system basis.
 To enable per-user quotas on a file system, add `userquota` to the options field in the [.filename]#/etc/fstab# entry for the file system to enable quotas on.
 For example:
 
 [.programlisting]
 ....
 /dev/da1s2g   /home    ufs rw,userquota 1 2
 ....
 
 To enable group quotas, use `groupquota` instead.
 To enable both user and group quotas, separate the options with a comma:
 
 [.programlisting]
 ....
 /dev/da1s2g    /home    ufs rw,userquota,groupquota 1 2
 ....
 
 By default, quota files are stored in the root directory of the file system as [.filename]#quota.user# and [.filename]#quota.group#.
 Refer to man:fstab[5] for more information.
 Specifying an alternate location for the quota files is not recommended.
 
 Once the configuration is complete, reboot the system and [.filename]#/etc/rc# will automatically run the appropriate commands to create the initial quota files for all of the quotas enabled in [.filename]#/etc/fstab#.
 
 In the normal course of operations, there should be no need to manually run man:quotacheck[8], man:quotaon[8], or man:quotaoff[8].
 However, one should read these manual pages to be familiar with their operation.
 
 === Setting Quota Limits
 
 To verify that quotas are enabled, run:
 
 [source,shell]
 ....
 # quota -v
 ....
 
 There should be a one line summary of disk usage and current quota limits for each file system that quotas are enabled on.
 
 The system is now ready to be assigned quota limits with `edquota`.
 
 Several options are available to enforce limits on the amount of disk space a user or group may allocate, and how many files they may create.
 Allocations can be limited based on disk space (block quotas), number of files (inode quotas), or a combination of both.
 Each limit is further broken down into two categories: hard and soft limits.
 
 A hard limit may not be exceeded.
 Once a user reaches a hard limit, no further allocations can be made on that file system by that user.
 For example, if the user has a hard limit of 500 kbytes on a file system and is currently using 490 kbytes, the user can only allocate an additional 10 kbytes.
 Attempting to allocate an additional 11 kbytes will fail.
 
 Soft limits can be exceeded for a limited amount of time, known as the grace period, which is one week by default.
 If a user stays over their limit longer than the grace period, the soft limit turns into a hard limit and no further allocations are allowed.
 When the user drops back below the soft limit, the grace period is reset.
 
 In the following example, the quota for the `test` account is being edited.
 When `edquota` is invoked, the editor specified by `EDITOR` is opened in order to edit the quota limits.
 The default editor is set to vi.
 
 [source,shell]
 ....
 # edquota -u test
 Quotas for user test:
 /usr: kbytes in use: 65, limits (soft = 50, hard = 75)
         inodes in use: 7, limits (soft = 50, hard = 60)
 /usr/var: kbytes in use: 0, limits (soft = 50, hard = 75)
         inodes in use: 0, limits (soft = 50, hard = 60)
 ....
 
 There are normally two lines for each file system that has quotas enabled.
 One line represents the block limits and the other represents the inode limits.
 Change the value to modify the quota limit.
 For example, to raise the block limit on [.filename]#/usr# to a soft limit of `500` and a hard limit of `600`, change the values in that line as follows:
 
 [.programlisting]
 ....
 /usr: kbytes in use: 65, limits (soft = 500, hard = 600)
 ....
 
 The new quota limits take effect upon exiting the editor.
 
 Sometimes it is desirable to set quota limits on a range of users.
 This can be done by first assigning the desired quota limit to a user.
 Then, use `-p` to duplicate that quota to a specified range of user IDs (UIDs).
 The following command will duplicate those quota limits for UIDs `10,000` through `19,999`:
 
 [source,shell]
 ....
 # edquota -p test 10000-19999
 ....
 
 For more information, refer to man:edquota[8].
 
 === Checking Quota Limits and Disk Usage
 
 To check individual user or group quotas and disk usage, use man:quota[1].
 A user may only examine their own quota and the quota of a group they are a member of.
 Only the superuser may view all user and group quotas.
 To get a summary of all quotas and disk usage for file systems with quotas enabled, use man:repquota[8].
 
 Normally, file systems that the user is not using any disk space on will not show in the output of `quota`, even if the user has a quota limit assigned for that file system.
 Use `-v` to display those file systems.
 The following is sample output from `quota -v` for a user that has quota limits on two file systems.
 
 [.programlisting]
 ....
 Disk quotas for user test (uid 1002):
      Filesystem  usage    quota   limit   grace   files   quota   limit   grace
            /usr      65*     50      75   5days       7      50      60
        /usr/var       0      50      75               0      50      60
 ....
 
 In this example, the user is currently 15 kbytes over the soft limit of 50 kbytes on [.filename]#/usr# and has 5 days of grace period left.
 The asterisk `*` indicates that the user is currently over the quota limit.
 
 === Quotas over NFS
 
 Quotas are enforced by the quota subsystem on the NFS server.
 The man:rpc.rquotad[8] daemon makes quota information available to `quota` on NFS clients, allowing users on those machines to see their quota statistics.
 
 On the NFS server, enable `rpc.rquotad` by removing the `#` from this line in [.filename]*/etc/inetd.conf*:
 
 [.programlisting]
 ....
 rquotad/1      dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotad
 ....
 
 Then, restart `inetd`:
 
 [source,shell]
 ....
 # service inetd restart
 ....
 
 [[disks-encrypting]]
 == Encrypting Disk Partitions
 
 FreeBSD offers excellent online protections against unauthorized data access.
 File permissions and crossref:mac[mac,Mandatory Access Control] (MAC) help prevent unauthorized users from accessing data while the operating system is active and the computer is powered up.
 However, the permissions enforced by the operating system are irrelevant if an attacker has physical access to a computer and can move the computer's hard drive to another system to copy and analyze the data.
 
 Regardless of how an attacker may have come into possession of a hard drive or powered-down computer, the GEOM-based cryptographic subsystems built into FreeBSD are able to protect the data on the computer's file systems against even highly-motivated attackers with significant resources.
 Unlike encryption methods that encrypt individual files, the built-in `gbde` and `geli` utilities can be used to transparently encrypt entire file systems.
 No cleartext ever touches the hard drive's platter.
 
 This chapter demonstrates how to create an encrypted file system on FreeBSD.
 It first demonstrates the process using `gbde` and then demonstrates the same example using `geli`.
 
 === Disk Encryption with gbde
 
 The objective of the man:gbde[4] facility is to provide a formidable challenge for an attacker to gain access to the contents of a _cold_ storage device. 
 However, if the computer is compromised while up and running and the storage device is actively attached, or the attacker has access to a valid passphrase, it offers no protection to the contents of the storage device.
 Thus, it is important to provide physical security while the system is running and to protect the passphrase used by the encryption mechanism.
 
 This facility provides several barriers to protect the data stored in each disk sector.
 It encrypts the contents of a disk sector using 128-bit AES in CBC mode.
 Each sector on the disk is encrypted with a different AES key.
 For more information on the cryptographic design, including how the sector keys are derived from the user-supplied passphrase, refer to man:gbde[4].
 
 FreeBSD provides a kernel module for gbde which can be loaded with this command:
 
 [source,shell]
 ....
 # kldload geom_bde
 ....
 
 If using a custom kernel configuration file, ensure it contains this line:
 
 `options GEOM_BDE`
 
 The following example demonstrates adding a new hard drive to a system that will hold a single encrypted partition that will be mounted as [.filename]#/private#.
 
 [.procedure]
 .Procedure: Encrypting a Partition with gbde
 . Add the New Hard Drive
-+ 
++
 Install the new drive to the system as explained in <<disks-adding>>.
 For the purposes of this example, a new hard drive partition has been added as [.filename]#/dev/ad4s1c# and [.filename]#/dev/ad0s1*# represents the existing standard FreeBSD partitions.
 +
 [source,shell]
 ....
 # ls /dev/ad*
 /dev/ad0        /dev/ad0s1b     /dev/ad0s1e     /dev/ad4s1
 /dev/ad0s1      /dev/ad0s1c     /dev/ad0s1f     /dev/ad4s1c
 /dev/ad0s1a     /dev/ad0s1d     /dev/ad4
 ....
 
 . Create a Directory to Hold `gbde` Lock Files
 +
 [source,shell]
 ....
 # mkdir /etc/gbde
 ....
-+ 
++
 The gbde lock file contains information that gbde requires to access encrypted partitions.
 Without access to the lock file, gbde will not be able to decrypt the data contained in the encrypted partition without significant manual intervention which is not supported by the software.
 Each encrypted partition uses a separate lock file.
 . Initialize the `gbde` Partition
-+ 
++
 A gbde partition must be initialized before it can be used.
 This initialization needs to be performed only once.
 This command will open the default editor, in order to set various configuration options in a template.
 For use with the UFS file system, set the sector_size to 2048:
 +
 [source,shell]
 ....
 # gbde init /dev/ad4s1c -i -L /etc/gbde/ad4s1c.lock
 # $FreeBSD: src/sbin/gbde/template.txt,v 1.1.36.1 2009/08/03 08:13:06 kensmith Exp $
 #
 # Sector size is the smallest unit of data which can be read or written.
 # Making it too small decreases performance and decreases available space.
 # Making it too large may prevent filesystems from working.  512 is the
 # minimum and always safe.  For UFS, use the fragment size
 #
 sector_size	=	2048
 [...]
 ....
-+ 
++
 Once the edit is saved, the user will be asked twice to type the passphrase used to secure the data.
 The passphrase must be the same both times.
 The ability of gbde to protect data depends entirely on the quality of the passphrase.
 For tips on how to select a secure passphrase that is easy to remember, see http://world.std.com/\~reinhold/diceware.html[http://world.std.com/~reinhold/diceware.htm].
-+ 
++
 This initialization creates a lock file for the gbde partition.
 In this example, it is stored as [.filename]#/etc/gbde/ad4s1c.lock#.
 Lock files must end in ".lock" in order to be correctly detected by the [.filename]#/etc/rc.d/gbde# start up script.
 +
 [CAUTION]
 ====
 Lock files _must_ be backed up together with the contents of any encrypted partitions.
 Without the lock file, the legitimate owner will be unable to access the data on the encrypted partition.
 ====
 
 . Attach the Encrypted Partition to the Kernel
 +
 [source,shell]
 ....
 # gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c.lock
 ....
-+ 
++
 This command will prompt to input the passphrase that was selected during the initialization of the encrypted partition.
 The new encrypted device will appear in [.filename]#/dev# as [.filename]#/dev/device_name.bde#:
 +
 [source,shell]
 ....
 # ls /dev/ad*
 /dev/ad0        /dev/ad0s1b     /dev/ad0s1e     /dev/ad4s1
 /dev/ad0s1      /dev/ad0s1c     /dev/ad0s1f     /dev/ad4s1c
 /dev/ad0s1a     /dev/ad0s1d     /dev/ad4        /dev/ad4s1c.bde
 ....
 
 . Create a File System on the Encrypted Device
-+ 
++
 Once the encrypted device has been attached to the kernel, a file system can be created on the device.
 This example creates a UFS file system with soft updates enabled.
 Be sure to specify the partition which has a [.filename]#*.bde# extension:
 +
 [source,shell]
 ....
 # newfs -U /dev/ad4s1c.bde
 ....
 
 . Mount the Encrypted Partition
-+ 
++
 Create a mount point and mount the encrypted file system:
 +
 [source,shell]
 ....
 # mkdir /private
 # mount /dev/ad4s1c.bde /private
 ....
 
 . Verify That the Encrypted File System is Available
-+ 
++
 The encrypted file system should now be visible and available for use:
 +
 [source,shell]
 ....
 % df -H
 Filesystem        Size   Used  Avail Capacity  Mounted on
 /dev/ad0s1a      1037M    72M   883M     8%    /
 /devfs            1.0K   1.0K     0B   100%    /dev
 /dev/ad0s1f       8.1G    55K   7.5G     0%    /home
 /dev/ad0s1e      1037M   1.1M   953M     0%    /tmp
 /dev/ad0s1d       6.1G   1.9G   3.7G    35%    /usr
 /dev/ad4s1c.bde   150G   4.1K   138G     0%    /private
 ....
 
 After each boot, any encrypted file systems must be manually re-attached to the kernel, checked for errors, and mounted, before the file systems can be used.
 To configure these steps, add the following lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 gbde_autoattach_all="YES"
 gbde_devices="ad4s1c"
 gbde_lockdir="/etc/gbde"
 ....
 
 This requires that the passphrase be entered at the console at boot time.
 After typing the correct passphrase, the encrypted partition will be mounted automatically.
 Additional gbde boot options are available and listed in man:rc.conf[5].
 
 [NOTE]
 ====
 sysinstall is incompatible with gbde-encrypted devices.
 All [.filename]#*.bde# devices must be detached from the kernel before starting sysinstall or it will crash during its initial probing for devices.
 To detach the encrypted device used in the example, use the following command:
 
 [source,shell]
 ....
 # gbde detach /dev/ad4s1c
 ....
 ====
 
 [[disks-encrypting-geli]]
 === Disk Encryption with `geli`
 
 An alternative cryptographic GEOM class is available using `geli`.
 This control utility adds some features and uses a different scheme for doing cryptographic work.
 It provides the following features:
 
 * Utilizes the man:crypto[9] framework and automatically uses cryptographic hardware when it is available.
 * Supports multiple cryptographic algorithms such as AES, Blowfish, and 3DES.
 * Allows the root partition to be encrypted. The passphrase used to access the encrypted root partition will be requested during system boot.
 * Allows the use of two independent keys.
 * It is fast as it performs simple sector-to-sector encryption.
 * Allows backup and restore of master keys. If a user destroys their keys, it is still possible to get access to the data by restoring keys from the backup.
 * Allows a disk to attach with a random, one-time key which is useful for swap partitions and temporary file systems.
 
 More features and usage examples can be found in man:geli[8].
 
 The following example describes how to generate a key file which will be used as part of the master key for the encrypted provider mounted under [.filename]#/private#.
 The key file will provide some random data used to encrypt the master key.
 The master key will also be protected by a passphrase.
 The provider's sector size will be 4kB.
 The example describes how to attach to the `geli` provider, create a file system on it, mount it, work with it, and finally, how to detach it.
 
 [.procedure]
 .Procedure: Encrypting a Partition with `geli`
 . Load `geli` Support
-+ 
++
 Support for `geli` is available as a loadable kernel module. To configure the system to automatically load the module at boot time, add the following line to [.filename]#/boot/loader.conf#:
 +
 [.programlisting]
 ....
 geom_eli_load="YES"
 ....
-+ 
++
 To load the kernel module now:
 +
 [source,shell]
 ....
 # kldload geom_eli
 ....
-+ 
++
 For a custom kernel, ensure the kernel configuration file contains these lines:
 +
 [.programlisting]
 ....
 options GEOM_ELI
 device crypto
 ....
 
 . Generate the Master Key
-+ 
++
 The following commands generate a master key that all data will be encrypted with.
 This key can never be changed.
 Rather than using it directly, it is encrypted with one or more user keys.
 The user keys are made up of an optional combination of random bytes from a file, [.filename]#/root/da2.key#, and/or a passphrase.
 In this case, the data source for the key file is [.filename]#/dev/random#.
 This command also configures the sector size of the provider ([.filename]#/dev/da2.eli#) as 4kB, for better performance:
 +
 [source,shell]
 ....
 # dd if=/dev/random of=/root/da2.key bs=64 count=1
 # geli init -K /root/da2.key -s 4096 /dev/da2
 Enter new passphrase:
 Reenter new passphrase:
 ....
-+ 
++
 It is not mandatory to use both a passphrase and a key file as either method of securing the master key can be used in isolation.
-+ 
++
 If the key file is given as "-", standard input will be used.
 For example, this command generates three key files:
 +
 [source,shell]
 ....
 # cat keyfile1 keyfile2 keyfile3 | geli init -K - /dev/da2
 ....
 
 . Attach the Provider with the Generated Key
-+ 
++
 To attach the provider, specify the key file, the name of the disk, and the passphrase:
 +
 [source,shell]
 ....
 # geli attach -k /root/da2.key /dev/da2
 Enter passphrase:
 ....
-+ 
++
 This creates a new device with an [.filename]#.eli# extension:
 +
 [source,shell]
 ....
 # ls /dev/da2*
 /dev/da2  /dev/da2.eli
 ....
 
 . Create the New File System
-+ 
++
 Next, format the device with the UFS file system and mount it on an existing mount point:
 +
 [source,shell]
 ....
 # dd if=/dev/random of=/dev/da2.eli bs=1m
 # newfs /dev/da2.eli
 # mount /dev/da2.eli /private
 ....
-+ 
++
 The encrypted file system should now be available for use:
 +
 [source,shell]
 ....
 # df -H
 Filesystem     Size   Used  Avail Capacity  Mounted on
 /dev/ad0s1a    248M    89M   139M    38%    /
 /devfs         1.0K   1.0K     0B   100%    /dev
 /dev/ad0s1f    7.7G   2.3G   4.9G    32%    /usr
 /dev/ad0s1d    989M   1.5M   909M     0%    /tmp
 /dev/ad0s1e    3.9G   1.3G   2.3G    35%    /var
 /dev/da2.eli   150G   4.1K   138G     0%    /private
 ....
 
 Once the work on the encrypted partition is done, and the [.filename]#/private# partition is no longer needed, it is prudent to put the device into cold storage by unmounting and detaching the `geli` encrypted partition from the kernel:
 
 [source,shell]
 ....
 # umount /private
 # geli detach da2.eli
 ....
 
 An [.filename]#rc.d# script is provided to simplify the mounting of `geli`-encrypted devices at boot time. For this example, add these lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 geli_devices="da2"
 geli_da2_flags="-k /root/da2.key"
 ....
 
 This configures [.filename]#/dev/da2# as a `geli` provider with a master key of [.filename]#/root/da2.key#.
 The system will automatically detach the provider from the kernel before the system shuts down.
 During the startup process, the script will prompt for the passphrase before attaching the provider.
 Other kernel messages might be shown before and after the password prompt.
 If the boot process seems to stall, look carefully for the password prompt among the other messages.
 Once the correct passphrase is entered, the provider is attached.
 The file system is then mounted, typically by an entry in [.filename]#/etc/fstab#.
 Refer to crossref:basics[mount-unmount,“Mounting and Unmounting File Systems”] for instructions on how to configure a file system to mount at boot time.
 
 [[swap-encrypting]]
 == Encrypting Swap
 
 Like the encryption of disk partitions, encryption of swap space is used to protect sensitive information.
 Consider an application that deals with passwords.
 As long as these passwords stay in physical memory, they are not written to disk and will be cleared after a reboot.
 However, if FreeBSD starts swapping out memory pages to free space, the passwords may be written to the disk unencrypted.
 Encrypting swap space can be a solution for this scenario.
 
 This section demonstrates how to configure an encrypted swap partition using man:gbde[8] or man:geli[8] encryption.
 It assumes that [.filename]#/dev/ada0s1b# is the swap partition.
 
 === Configuring Encrypted Swap
 
 Swap partitions are not encrypted by default and should be cleared of any sensitive data before continuing.
 To overwrite the current swap partition with random garbage, execute the following command:
 
 [source,shell]
 ....
 # dd if=/dev/random of=/dev/ada0s1b bs=1m
 ....
 
 To encrypt the swap partition using man:gbde[8], add the `.bde` suffix to the swap line in [.filename]#/etc/fstab#:
 
 [.programlisting]
 ....
 # Device		Mountpoint	FStype	Options		Dump	Pass#
 /dev/ada0s1b.bde	none		swap	sw		0	0
 ....
 
 To instead encrypt the swap partition using man:geli[8], use the `.eli` suffix:
 
 [.programlisting]
 ....
 # Device		Mountpoint	FStype	Options		Dump	Pass#
 /dev/ada0s1b.eli	none		swap	sw		0	0
 ....
 
 By default, man:geli[8] uses the AES algorithm with a key length of 128 bits.
 Normally the default settings will suffice.
 If desired, these defaults can be altered in the options field in [.filename]#/etc/fstab#. The possible flags are:
 
 aalgo::
 Data integrity verification algorithm used to ensure that the encrypted data has not been tampered with.
 See man:geli[8] for a list of supported algorithms.
 
 ealgo::
 Encryption algorithm used to protect the data.
 See man:geli[8] for a list of supported algorithms.
 
 keylen::
 The length of the key used for the encryption algorithm.
 See man:geli[8] for the key lengths that are supported by each encryption algorithm.
 
 sectorsize::
 The size of the blocks data is broken into before it is encrypted.
 Larger sector sizes increase performance at the cost of higher storage overhead.
 The recommended size is 4096 bytes.
 
 This example configures an encrypted swap partition using the Blowfish algorithm with a key length of 128 bits and a sectorsize of 4 kilobytes:
 
 [.programlisting]
 ....
 # Device		Mountpoint	FStype	Options				Dump	Pass#
 /dev/ada0s1b.eli	none		swap	sw,ealgo=blowfish,keylen=128,sectorsize=4096	0	0
 ....
 
 === Encrypted Swap Verification
 
 Once the system has rebooted, proper operation of the encrypted swap can be verified using `swapinfo`.
 
 If man:gbde[8] is being used:
 
 [source,shell]
 ....
 % swapinfo
 Device          1K-blocks     Used    Avail Capacity
 /dev/ada0s1b.bde   542720        0   542720     0
 ....
 
 If man:geli[8] is being used:
 
 [source,shell]
 ....
 % swapinfo
 Device          1K-blocks     Used    Avail Capacity
 /dev/ada0s1b.eli   542720        0   542720     0
 ....
 
 [[disks-hast]]
 == Highly Available Storage (HAST)
 
 High availability is one of the main requirements in serious business applications and highly-available storage is a key component in such environments. 
 In FreeBSD, the Highly Available STorage (HAST) framework allows transparent storage of the same data across several physically separated machines connected by a TCP/IP network.
 HAST can be understood as a network-based RAID1 (mirror), and is similar to the DRBD(R) storage system used in the GNU/Linux(R) platform.
 In combination with other high-availability features of FreeBSD like CARP, HAST makes it possible to build a highly-available storage cluster that is resistant to hardware failures.
 
 The following are the main features of HAST:
 
 * Can be used to mask I/O errors on local hard drives.
 * File system agnostic as it works with any file system supported by FreeBSD.
 * Efficient and quick resynchronization as only the blocks that were modified during the downtime of a node are synchronized.
 * Can be used in an already deployed environment to add additional redundancy.
 * Together with CARP, Heartbeat, or other tools, it can be used to build a robust and durable storage system.
 
 After reading this section, you will know:
 
 * What HAST is, how it works, and which features it provides.
 * How to set up and use HAST on FreeBSD.
 * How to integrate CARP and man:devd[8] to build a robust storage system.
 
 Before reading this section, you should:
 
 * Understand UNIX(R) and FreeBSD basics (crossref:basics[basics,FreeBSD Basics]).
 * Know how to configure network interfaces and other core FreeBSD subsystems (crossref:config[config-tuning,Configuration and Tuning]).
 * Have a good understanding of FreeBSD networking (crossref:partiv[network-communication,"Network Communication"]).
 
 The HAST project was sponsored by The FreeBSD Foundation with support from http://www.omc.net/[http://www.omc.net/] and http://www.transip.nl/[http://www.transip.nl/].
 
 === HAST Operation
 
 HAST provides synchronous block-level replication between two physical machines: the _primary_, also known as the _master_ node, and the _secondary_, or _slave_ node.
 These two machines together are referred to as a cluster.
 
 Since HAST works in a primary-secondary configuration, it allows only one of the cluster nodes to be active at any given time.
 The primary node, also called _active_, is the one which will handle all the I/O requests to HAST-managed devices.
 The secondary node is automatically synchronized from the primary node.
 
 The physical components of the HAST system are the local disk on primary node, and the disk on the remote, secondary node.
 
 HAST operates synchronously on a block level, making it transparent to file systems and applications.
 HAST provides regular GEOM providers in [.filename]#/dev/hast/# for use by other tools or applications.
 There is no difference between using HAST-provided devices and raw disks or partitions.
 
 Each write, delete, or flush operation is sent to both the local disk and to the remote disk over TCP/IP.
 Each read operation is served from the local disk, unless the local disk is not up-to-date or an I/O error occurs.
 In such cases, the read operation is sent to the secondary node.
 
 HAST tries to provide fast failure recovery.
 For this reason, it is important to reduce synchronization time after a node's outage.
 To provide fast synchronization, HAST manages an on-disk bitmap of dirty extents and only synchronizes those during a regular synchronization, with an exception of the initial sync.
 
 There are many ways to handle synchronization.
 HAST implements several replication modes to handle different synchronization methods:
 
 * _memsync_: This mode reports a write operation as completed when the local write operation is finished and when the remote node acknowledges data arrival, but before actually storing the data. The data on the remote node will be stored directly after sending the acknowledgement. This mode is intended to reduce latency, but still provides good reliability. This mode is the default.
 * _fullsync_: This mode reports a write operation as completed when both the local write and the remote write complete. This is the safest and the slowest replication mode.
 * _async_: This mode reports a write operation as completed when the local write completes. This is the fastest and the most dangerous replication mode. It should only be used when replicating to a distant node where latency is too high for other modes.
 
 === HAST Configuration
 
 The HAST framework consists of several components:
 
 * The man:hastd[8] daemon which provides data synchronization. When this daemon is started, it will automatically load `geom_gate.ko`.
 * The userland management utility, man:hastctl[8].
 * The man:hast.conf[5] configuration file. This file must exist before starting hastd.
 
 Users who prefer to statically build `GEOM_GATE` support into the kernel should add this line to the custom kernel configuration file, then rebuild the kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel]:
 
 [.programlisting]
 ....
 options	GEOM_GATE
 ....
 
 The following example describes how to configure two nodes in master-slave/primary-secondary operation using HAST to replicate the data between the two.
 The nodes will be called `hasta`, with an IP address of `172.16.0.1`, and `hastb`, with an IP address of `172.16.0.2`.
 Both nodes will have a dedicated hard drive [.filename]#/dev/ad6# of the same size for HAST operation.
 The HAST pool, sometimes referred to as a resource or the GEOM provider in [.filename]#/dev/hast/#, will be called `test`.
 
 Configuration of HAST is done using [.filename]#/etc/hast.conf#. 
 This file should be identical on both nodes.
 The simplest configuration is:
 
 [.programlisting]
 ....
 resource test {
 	on hasta {
 		local /dev/ad6
 		remote 172.16.0.2
 	}
 	on hastb {
 		local /dev/ad6
 		remote 172.16.0.1
 	}
 }
 ....
 
 For more advanced configuration, refer to man:hast.conf[5].
 
 [TIP]
 ====
 It is also possible to use host names in the `remote` statements if the hosts are resolvable and defined either in [.filename]#/etc/hosts# or in the local DNS.
 ====
 
 Once the configuration exists on both nodes, the HAST pool can be created.
 Run these commands on both nodes to place the initial metadata onto the local disk and to start man:hastd[8]:
 
 [source,shell]
 ....
 # hastctl create test
 # service hastd onestart
 ....
 
 [NOTE]
 ====
 It is _not_ possible to use GEOM providers with an existing file system or to convert an existing storage to a HAST-managed pool.
 This procedure needs to store some metadata on the provider and there will not be enough required space available on an existing provider.
 ====
 
 A HAST node's `primary` or `secondary` role is selected by an administrator, or software like Heartbeat, using man:hastctl[8].
 On the primary node, `hasta`, issue this command:
 
 [source,shell]
 ....
 # hastctl role primary test
 ....
 
 Run this command on the secondary node, `hastb`:
 
 [source,shell]
 ....
 # hastctl role secondary test
 ....
 
 Verify the result by running `hastctl` on each node:
 
 [source,shell]
 ....
 # hastctl status test
 ....
 
 Check the `status` line in the output.
 If it says `degraded`, something is wrong with the configuration file.
 It should say `complete` on each node, meaning that the synchronization between the nodes has started.
 The synchronization completes when `hastctl status` reports 0 bytes of `dirty` extents.
 
 The next step is to create a file system on the GEOM provider and mount it.
 This must be done on the `primary` node.
 Creating the file system can take a few minutes, depending on the size of the hard drive.
 This example creates a UFS file system on [.filename]#/dev/hast/test#:
 
 [source,shell]
 ....
 # newfs -U /dev/hast/test
 # mkdir /hast/test
 # mount /dev/hast/test /hast/test
 ....
 
 Once the HAST framework is configured properly, the final step is to make sure that HAST is started automatically during system boot.
 Add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 hastd_enable="YES"
 ....
 
 ==== Failover Configuration
 
 The goal of this example is to build a robust storage system which is resistant to the failure of any given node.
 If the primary node fails, the secondary node is there to take over seamlessly, check and mount the file system, and continue to work without missing a single bit of data.
 
 To accomplish this task, the Common Address Redundancy Protocol (CARP) is used to provide for automatic failover at the IP layer.
 CARP allows multiple hosts on the same network segment to share an IP address.
 Set up CARP on both nodes of the cluster according to the documentation available in crossref:advanced-networking[carp,“Common Address Redundancy Protocol (CARP)”].
 In this example, each node will have its own management IP address and a shared IP address of _172.16.0.254_.
 The primary HAST node of the cluster must be the master CARP node.
 
 The HAST pool created in the previous section is now ready to be exported to the other hosts on the network.
 This can be accomplished by exporting it through NFS or Samba, using the shared IP address _172.16.0.254_.
 The only problem which remains unresolved is an automatic failover should the primary node fail.
 
 In the event of CARP interfaces going up or down, the FreeBSD operating system generates a man:devd[8] event, making it possible to watch for state changes on the CARP interfaces.
 A state change on the CARP interface is an indication that one of the nodes failed or came back online.
 These state change events make it possible to run a script which will automatically handle the HAST failover.
 
 To catch state changes on the CARP interfaces, add this configuration to [.filename]#/etc/devd.conf# on each node:
 
 [.programlisting]
 ....
 notify 30 {
 	match "system" "IFNET";
 	match "subsystem" "carp0";
 	match "type" "LINK_UP";
 	action "/usr/local/sbin/carp-hast-switch master";
 };
 
 notify 30 {
 	match "system" "IFNET";
 	match "subsystem" "carp0";
 	match "type" "LINK_DOWN";
 	action "/usr/local/sbin/carp-hast-switch slave";
 };
 ....
 
 [NOTE]
 ====
 If the systems are running FreeBSD 10 or higher, replace [.filename]#carp0# with the name of the CARP-configured interface.
 ====
 
 Restart man:devd[8] on both nodes to put the new configuration into effect:
 
 [source,shell]
 ....
 # service devd restart
 ....
 
 When the specified interface state changes by going up or down , the system generates a notification, allowing the man:devd[8] subsystem to run the specified automatic failover script, [.filename]#/usr/local/sbin/carp-hast-switch#.
 For further clarification about this configuration, refer to man:devd.conf[5].
 
 Here is an example of an automated failover script:
 
 [.programlisting]
 ....
 #!/bin/sh
 
 # Original script by Freddie Cash <fjwcash@gmail.com>
 # Modified by Michael W. Lucas <mwlucas@BlackHelicopters.org>
 # and Viktor Petersson <vpetersson@wireload.net>
 
 # The names of the HAST resources, as listed in /etc/hast.conf
 resources="test"
 
 # delay in mounting HAST resource after becoming master
 # make your best guess
 delay=3
 
 # logging
 log="local0.debug"
 name="carp-hast"
 
 # end of user configurable stuff
 
 case "$1" in
 	master)
 		logger -p $log -t $name "Switching to primary provider for ${resources}."
 		sleep ${delay}
 
 		# Wait for any "hastd secondary" processes to stop
 		for disk in ${resources}; do
 			while $( pgrep -lf "hastd: ${disk} \(secondary\)" > /dev/null 2>&1 ); do
 				sleep 1
 			done
 
 			# Switch role for each disk
 			hastctl role primary ${disk}
 			if [ $? -ne 0 ]; then
 				logger -p $log -t $name "Unable to change role to primary for resource ${disk}."
 				exit 1
 			fi
 		done
 
 		# Wait for the /dev/hast/* devices to appear
 		for disk in ${resources}; do
 			for I in $( jot 60 ); do
 				[ -c "/dev/hast/${disk}" ] && break
 				sleep 0.5
 			done
 
 			if [ ! -c "/dev/hast/${disk}" ]; then
 				logger -p $log -t $name "GEOM provider /dev/hast/${disk} did not appear."
 				exit 1
 			fi
 		done
 
 		logger -p $log -t $name "Role for HAST resources ${resources} switched to primary."
 
 		logger -p $log -t $name "Mounting disks."
 		for disk in ${resources}; do
 			mkdir -p /hast/${disk}
 			fsck -p -y -t ufs /dev/hast/${disk}
 			mount /dev/hast/${disk} /hast/${disk}
 		done
 
 	;;
 
 	slave)
 		logger -p $log -t $name "Switching to secondary provider for ${resources}."
 
 		# Switch roles for the HAST resources
 		for disk in ${resources}; do
 			if ! mount | grep -q "^/dev/hast/${disk} on "
 			then
 			else
 				umount -f /hast/${disk}
 			fi
 			sleep $delay
 			hastctl role secondary ${disk} 2>&1
 			if [ $? -ne 0 ]; then
 				logger -p $log -t $name "Unable to switch role to secondary for resource ${disk}."
 				exit 1
 			fi
 			logger -p $log -t $name "Role switched to secondary for resource ${disk}."
 		done
 	;;
 esac
 ....
 
 In a nutshell, the script takes these actions when a node becomes master:
 
 * Promotes the HAST pool to primary on the other node.
 * Checks the file system under the HAST pool.
 * Mounts the pool.
 
 When a node becomes secondary:
 
 * Unmounts the HAST pool.
 * Degrades the HAST pool to secondary.
 
 [CAUTION]
 ====
 This is just an example script which serves as a proof of concept.
 It does not handle all the possible scenarios and can be extended or altered in any way, for example, to start or stop required services.
 ====
 
 [TIP]
 ====
 For this example, a standard UFS file system was used.
 To reduce the time needed for recovery, a journal-enabled UFS or ZFS file system can be used instead.
 ====
 
 More detailed information with additional examples can be found at http://wiki.FreeBSD.org/HAST[http://wiki.FreeBSD.org/HAST].
 
 === Troubleshooting
 
 HAST should generally work without issues.
 However, as with any other software product, there may be times when it does not work as supposed.
 The sources of the problems may be different, but the rule of thumb is to ensure that the time is synchronized between the nodes of the cluster.
 
 When troubleshooting HAST, the debugging level of man:hastd[8] should be increased by starting `hastd` with `-d`.
 This argument may be specified multiple times to further increase the debugging level.
 Consider also using `-F`, which starts `hastd` in the foreground.
 
 [[disks-hast-sb]]
 ==== Recovering from the Split-brain Condition
 
 _Split-brain_ occurs when the nodes of the cluster are unable to communicate with each other, and both are configured as primary.
 This is a dangerous condition because it allows both nodes to make incompatible changes to the data.
 This problem must be corrected manually by the system administrator.
 
 The administrator must either decide which node has more important changes, or perform the merge manually.
 Then, let HAST perform full synchronization of the node which has the broken data.
 To do this, issue these commands on the node which needs to be resynchronized:
 
 [source,shell]
 ....
 # hastctl role init test
 # hastctl create test
 # hastctl role secondary test
 ....
diff --git a/documentation/content/en/books/handbook/firewalls/_index.adoc b/documentation/content/en/books/handbook/firewalls/_index.adoc
index 0859280681..47429914bc 100644
--- a/documentation/content/en/books/handbook/firewalls/_index.adoc
+++ b/documentation/content/en/books/handbook/firewalls/_index.adoc
@@ -1,2681 +1,2681 @@
 ---
 title: Chapter 31. Firewalls
 part: IV. Network Communication
 prev: books/handbook/network-servers
 next: books/handbook/advanced-networking
 description: "FreeBSD has three firewalls built into the base system: PF, IPFW, and IPFILTER. This chapter covers how to define packet filtering rules, the differences between the firewalls built into FreeBSD and how to use them"
 tags: ["firewall", "pf", "ipfw", "ipfilter", "blacklistd", "filtering"]
 ---
 
 [[firewalls]]
 = Firewalls
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 31
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/firewalls/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/firewalls/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/firewalls/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[firewalls-intro]]
 == Synopsis
 
 Firewalls make it possible to filter the incoming and outgoing traffic that flows through a system.
 A firewall can use one or more sets of "rules" to inspect network packets as they come in or go out of network connections and either allows the traffic through or blocks it.
 The rules of a firewall can inspect one or more characteristics of the packets such as the protocol type, source or destination host address, and source or destination port.
 
 Firewalls can enhance the security of a host or a network.
 They can be used to do one or more of the following:
 
 * Protect and insulate the applications, services, and machines of an internal network from unwanted traffic from the public Internet.
 * Limit or disable access from hosts of the internal network to services of the public Internet.
 * Support network address translation (NAT), which allows an internal network to use private IP addresses and share a single connection to the public Internet using either a single IP address or a shared pool of automatically assigned public addresses.
 
 FreeBSD has three firewalls built into the base system: PF, IPFW, and IPFILTER, also known as IPF.
 FreeBSD also provides two traffic shapers for controlling bandwidth usage: man:altq[4] and man:dummynet[4].
 ALTQ has traditionally been closely tied with PF and dummynet with IPFW.
 Each firewall uses rules to control the access of packets to and from a FreeBSD system, although they go about it in different ways and each has a different rule syntax.
 
 FreeBSD provides multiple firewalls in order to meet the different requirements and preferences for a wide variety of users.
 Each user should evaluate which firewall best meets their needs.
 
 After reading this chapter, you will know:
 
 * How to define packet filtering rules.
 * The differences between the firewalls built into FreeBSD.
 * How to use and configure the PF firewall.
 * How to use and configure the IPFW firewall.
 * How to use and configure the IPFILTER firewall.
 
 Before reading this chapter, you should:
 
 * Understand basic FreeBSD and Internet concepts.
 
 [NOTE]
 ====
 Since all firewalls are based on inspecting the values of selected packet control fields, the creator of the firewall ruleset must have an understanding of how TCP/IP works, what the different values in the packet control fields are, and how these values are used in a normal session conversation.
 For a good introduction, refer to http://www.ipprimer.com[Daryl's TCP/IP Primer].
 ====
 
 [[firewalls-concepts]]
 == Firewall Concepts
 
 A ruleset contains a group of rules which pass or block packets based on the values contained in the packet.
 The bi-directional exchange of packets between hosts comprises a session conversation.
 The firewall ruleset processes both the packets arriving from the public Internet, as well as the packets produced by the system as a response to them. 
 Each TCP/IP service is predefined by its protocol and listening port.
 Packets destined for a specific service originate from the source address using an unprivileged port and target the specific service port on the destination address.
 All the above parameters can be used as selection criteria to create rules which will pass or block services.
 
 To lookup unknown port numbers, refer to [.filename]#/etc/services#.
 Alternatively, visit http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers[http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers] and do a port number lookup to find the purpose of a particular port number.
 
 Check out this link for http://web.archive.org/web/20150803024617/http://www.sans.org/security-resources/idfaq/oddports.php[port numbers used by Trojans].
 
 FTP has two modes: active mode and passive mode.
 The difference is in how the data channel is acquired.
 Passive mode is more secure as the data channel is acquired by the ordinal ftp session requester.
 For a good explanation of FTP and the different modes, see http://www.slacksite.com/other/ftp.html[http://www.slacksite.com/other/ftp.html].
 
 A firewall ruleset can be either "exclusive" or "inclusive".
 An exclusive firewall allows all traffic through except for the traffic matching the ruleset.
 An inclusive firewall does the reverse as it only allows traffic matching the rules through and blocks everything else.
 
 An inclusive firewall offers better control of the outgoing traffic, making it a better choice for systems that offer services to the public Internet.
 It also controls the type of traffic originating from the public Internet that can gain access to a private network.
 All traffic that does not match the rules is blocked and logged.
 Inclusive firewalls are generally safer than exclusive firewalls because they significantly reduce the risk of allowing unwanted traffic.
 
 [NOTE]
 ====
 Unless noted otherwise, all configuration and example rulesets in this chapter create inclusive firewall rulesets.
 ====
 
 Security can be tightened further using a "stateful firewall".
 This type of firewall keeps track of open connections and only allows traffic which either matches an existing connection or opens a new, allowed connection.
 
 Stateful filtering treats traffic as a bi-directional exchange of packets comprising a session.
 When state is specified on a matching rule the firewall dynamically generates internal rules for each anticipated packet being exchanged during the session.
 It has sufficient matching capabilities to determine if a packet is valid for a session.
 Any packets that do not properly fit the session template are automatically rejected.
 
 When the session completes, it is removed from the dynamic state table.
 
 Stateful filtering allows one to focus on blocking/passing new sessions.
 If the new session is passed, all its subsequent packets are allowed automatically and any impostor packets are automatically rejected.
 If a new session is blocked, none of its subsequent packets are allowed.
 Stateful filtering provides advanced matching abilities capable of defending against the flood of different attack methods employed by attackers.
 
 NAT stands for _Network Address Translation_.
 NAT function enables the private LAN behind the firewall to share a single ISP-assigned IP address, even if that address is dynamically assigned.
 NAT allows each computer in the LAN to have Internet access, without having to pay the ISP for multiple Internet accounts or IP addresses.
 
 NAT will automatically translate the private LAN IP address for each system on the LAN to the single public IP address as packets exit the firewall bound for the public Internet.
 It also performs the reverse translation for returning packets.
 
 According to RFC 1918, the following IP address ranges are reserved for private networks which will never be routed directly to the public Internet, and therefore are available for use with NAT:
 
 * `10.0.0.0/8`.
 * `172.16.0.0/12`.
 * `192.168.0.0/16`.
 
 [WARNING]
 ====
 When working with the firewall rules, be _very careful_.
 Some configurations _can lock the administrator out_ of the server.
 To be on the safe side, consider performing the initial firewall configuration from the local console rather than doing it remotely over ssh.
 ====
 
 [[firewalls-pf]]
 == PF
 
 Since FreeBSD 5.3, a ported version of OpenBSD's PF firewall has been included as an integrated part of the base system.
 PF is a complete, full-featured firewall that has optional support for ALTQ (Alternate Queuing), which provides Quality of Service (QoS).
 
 The OpenBSD Project maintains the definitive reference for PF in the http://www.openbsd.org/faq/pf/[PF FAQ].
 Peter Hansteen maintains a thorough PF tutorial at http://home.nuug.no/\~peter/pf/[http://home.nuug.no/~peter/pf/].
 
 [WARNING]
 ====
 When reading the http://www.openbsd.org/faq/pf/[PF FAQ], keep in mind that FreeBSD's version of PF has diverged substantially from the upstream OpenBSD version over the years.
 Not all features work the same way on FreeBSD as they do in OpenBSD and vice versa.
 ====
 
 The {freebsd-pf} is a good place to ask questions about configuring and running the PF firewall.
 Check the mailing list archives before asking a question as it may have already been answered.
 
 This section of the Handbook focuses on PF as it pertains to FreeBSD.
 It demonstrates how to enable PF and ALTQ.
 It also provides several examples for creating rulesets on a FreeBSD system.
 
 === Enabling PF
 
 To use PF, its kernel module must be first loaded.
 This section describes the entries that can be added to [.filename]#/etc/rc.conf# to enable PF.
 
 Start by adding `pf_enable=yes` to [.filename]#/etc/rc.conf#:
 
 [source,shell]
 ....
 # sysrc pf_enable=yes
 ....
 
 Additional options, described in man:pfctl[8], can be passed to PF when it is started.
 Add or change this entry in [.filename]#/etc/rc.conf# and specify any required flags between the two quotes (`""`):
 
 [.programlisting]
 ....
 pf_flags=""                     # additional flags for pfctl startup
 ....
 
 PF will not start if it cannot find its ruleset configuration file.
 By default, FreeBSD does not ship with a ruleset and there is no [.filename]#/etc/pf.conf#.
 Example rulesets can be found in [.filename]#/usr/share/examples/pf/#.
 If a custom ruleset has been saved somewhere else, add a line to [.filename]#/etc/rc.conf# which specifies the full path to the file:
 
 [.programlisting]
 ....
 pf_rules="/path/to/pf.conf"
 ....
 
 Logging support for PF is provided by man:pflog[4].
 To enable logging support, add `pflog_enable=yes` to [.filename]#/etc/rc.conf#:
 
 [source,shell]
 ....
 # sysrc pflog_enable=yes
 ....
 
 The following lines can also be added to change the default location of the log file or to specify any additional flags to pass to man:pflog[4] when it is started:
 
 [.programlisting]
 ....
 pflog_logfile="/var/log/pflog"  # where pflogd should store the logfile
 pflog_flags=""                  # additional flags for pflogd startup
 ....
 
 Finally, if there is a LAN behind the firewall and packets need to be forwarded for the computers on the LAN, or NAT is required, enable the following option:
 
 [.programlisting]
 ....
 gateway_enable="YES"            # Enable as LAN gateway
 ....
 
 After saving the needed edits, PF can be started with logging support by typing:
 
 [source,shell]
 ....
 # service pf start
 # service pflog start
 ....
 
 By default, PF reads its configuration rules from [.filename]#/etc/pf.conf# and modifies, drops, or passes packets according to the rules or definitions specified in this file.
 The FreeBSD installation includes several sample files located in [.filename]#/usr/share/examples/pf/#.
 Refer to the http://www.openbsd.org/faq/pf/[PF FAQ] for complete coverage of PF rulesets.
 
 To control PF, use `pfctl`.
 <<pfctl>> summarizes some useful options to this command.
 Refer to man:pfctl[8] for a description of all available options:
 [[pfctl]]
 .Useful `pfctl` Options
 [cols="1,1", frame="none", options="header"]
 |===
 | Command
 | Purpose
 
 |`pfctl -e`
 |Enable PF.
 
 |`pfctl -d`
 |Disable PF.
 
 |`pfctl -F all -f /etc/pf.conf`
 |Flush all NAT, filter, state, and table rules and reload [.filename]#/etc/pf.conf#.
 
 |`pfctl -s [ rules \| nat \| states ]`
 |Report on the filter rules, NAT rules, or state table.
 
 |`pfctl -vnf /etc/pf.conf`
 |Check [.filename]#/etc/pf.conf# for errors, but do not load ruleset.
 |===
 
 [TIP]
 ====
 package:security/sudo[] is useful for running commands like `pfctl` that require elevated privileges.
 It can be installed from the Ports Collection.
 ====
 
 To keep an eye on the traffic that passes through the PF firewall, consider installing the package:sysutils/pftop[] package or port.
 Once installed, pftop can be run to view a running snapshot of traffic in a format which is similar to man:top[1].
 
 [[pf-tutorial]]
 === PF Rulesets
 
 This section demonstrates how to create a customized ruleset.
 It starts with the simplest of rulesets and builds upon its concepts using several examples to demonstrate real-world usage of PF's many features.
 
 The simplest possible ruleset is for a single machine that does not run any services and which needs access to one network, which may be the Internet.
 To create this minimal ruleset, edit [.filename]#/etc/pf.conf# so it looks like this:
 
 [.programlisting]
 ....
 block in all
 pass out all keep state
 ....
 
 The first rule denies all incoming traffic by default.
 The second rule allows connections created by this system to pass out, while retaining state information on those connections.
 This state information allows return traffic for those connections to pass back and should only be used on machines that can be trusted.
 The ruleset can be loaded with:
 
 [source,shell]
 ....
 # pfctl -e ; pfctl -f /etc/pf.conf
 ....
 
 In addition to keeping state, PF provides _lists_ and _macros_ which can be defined for use when creating rules.
 Macros can include lists and need to be defined before use.
 As an example, insert these lines at the very top of the ruleset:
 
 [.programlisting]
 ....
 tcp_services = "{ ssh, smtp, domain, www, pop3, auth, pop3s }"
 udp_services = "{ domain }"
 ....
 
 PF understands port names as well as port numbers, as long as the names are listed in [.filename]#/etc/services#.
 This example creates two macros.
 The first is a list of seven TCP port names and the second is one UDP port name.
 Once defined, macros can be used in rules.
 In this example, all traffic is blocked except for the connections initiated by this system for the seven specified TCP services and the one specified UDP service:
 
 [.programlisting]
 ....
 tcp_services = "{ ssh, smtp, domain, www, pop3, auth, pop3s }"
 udp_services = "{ domain }"
 block all
 pass out proto tcp to any port $tcp_services keep state
 pass proto udp to any port $udp_services keep state
 ....
 
 Even though UDP is considered to be a stateless protocol, PF is able to track some state information.
 For example, when a UDP request is passed which asks a name server about a domain name, PF will watch for the response to pass it back.
 
 Whenever an edit is made to a ruleset, the new rules must be loaded so they can be used:
 
 [source,shell]
 ....
 # pfctl -f /etc/pf.conf
 ....
 
 If there are no syntax errors, `pfctl` will not output any messages during the rule load.
 Rules can also be tested before attempting to load them:
 
 [source,shell]
 ....
 # pfctl -nf /etc/pf.conf
 ....
 
 Including `-n` causes the rules to be interpreted only, but not loaded.
 This provides an opportunity to correct any errors.
 At all times, the last valid ruleset loaded will be enforced until either PF is disabled or a new ruleset is loaded.
 
 [TIP]
 ====
 Adding `-v` to a `pfctl` ruleset verify or load will display the fully parsed rules exactly the way they will be loaded.
 This is extremely useful when debugging rules.
 ====
 
 [[pftut-gateway]]
 ==== A Simple Gateway with NAT
 
 This section demonstrates how to configure a FreeBSD system running PF to act as a gateway for at least one other machine.
 The gateway needs at least two network interfaces, each connected to a separate network.
 In this example, [.filename]#xl0# is connected to the Internet and [.filename]#xl1# is connected to the internal network.
 
 First, enable the gateway to let the machine forward the network traffic it receives on one interface to another interface.
 This sysctl setting will forward IPv4 packets:
 
 [source,shell]
 ....
 # sysctl net.inet.ip.forwarding=1
 ....
 
 To forward IPv6 traffic, use:
 
 [source,shell]
 ....
 # sysctl net.inet6.ip6.forwarding=1
 ....
 
 To enable these settings at system boot, use man:sysrc[8] to add them to [.filename]#/etc/rc.conf#:
 
 [source,shell]
 ....
 # sysrc gateway_enable=yes
 # sysrc ipv6_gateway_enable=yes
 ....
 
 Verify with `ifconfig` that both of the interfaces are up and running.
 
 Next, create the PF rules to allow the gateway to pass traffic.
 While the following rule allows stateful traffic from hosts of the internal network to pass to the gateway, the `to` keyword does not guarantee passage all the way from source to destination:
 
 [.programlisting]
 ....
 pass in on xl1 from xl1:network to xl0:network port $ports keep state
 ....
 
 That rule only lets the traffic pass in to the gateway on the internal interface.
 To let the packets go further, a matching rule is needed:
 
 [.programlisting]
 ....
 pass out on xl0 from xl1:network to xl0:network port $ports keep state
 ....
 
 While these two rules will work, rules this specific are rarely needed.
 For a busy network admin, a readable ruleset is a safer ruleset.
 The remainder of this section demonstrates how to keep the rules as simple as possible for readability.
 For example, those two rules could be replaced with one rule:
 
 [.programlisting]
 ....
 pass from xl1:network to any port $ports keep state
 ....
 
 The `interface:network` notation can be replaced with a macro to make the ruleset even more readable.
 For example, a `$localnet` macro could be defined as the network directly attached to the internal interface (`$xl1:network`).
 Alternatively, the definition of `$localnet` could be changed to an _IP address/netmask_ notation to denote a network, such as `192.168.100.1/24` for a subnet of private addresses.
 
 If required, `$localnet` could even be defined as a list of networks.
 Whatever the specific needs, a sensible `$localnet` definition could be used in a typical pass rule as follows:
 
 [.programlisting]
 ....
 pass from $localnet to any port $ports keep state
 ....
 
 The following sample ruleset allows all traffic initiated by machines on the internal network.
 It first defines two macros to represent the external and internal 3COM interfaces of the gateway.
 
 [NOTE]
 ====
 For dialup users, the external interface will use [.filename]#tun0#.
 For an ADSL connection, specifically those using PPP over Ethernet (PPPoE), the correct external interface is [.filename]#tun0#, not the physical Ethernet interface.
 ====
 
 [.programlisting]
 ....
 ext_if = "xl0"	# macro for external interface - use tun0 for PPPoE
 int_if = "xl1"	# macro for internal interface
 localnet = $int_if:network
 # ext_if IP address could be dynamic, hence ($ext_if)
 nat on $ext_if from $localnet to any -> ($ext_if)
 block all
 pass from { lo0, $localnet } to any keep state
 ....
 
 This ruleset introduces the `nat` rule which is used to handle the network address translation from the non-routable addresses inside the internal network to the IP address assigned to the external interface.
 The parentheses surrounding the last part of the nat rule `($ext_if)` is included when the IP address of the external interface is dynamically assigned.
 It ensures that network traffic runs without serious interruptions even if the external IP address changes.
 
 Note that this ruleset probably allows more traffic to pass out of the network than is needed.
 One reasonable setup could create this macro:
 
 [.programlisting]
 ....
 client_out = "{ ftp-data, ftp, ssh, domain, pop3, auth, nntp, http, \
     https, cvspserver, 2628, 5999, 8000, 8080 }"
 ....
 
 to use in the main pass rule:
 
 [.programlisting]
 ....
 pass inet proto tcp from $localnet to any port $client_out \
     flags S/SA keep state
 ....
 
 A few other pass rules may be needed.
 This one enables SSH on the external interface:
 
 [.programlisting]
 ....
 pass in inet proto tcp to $ext_if port ssh
 ....
 
 This macro definition and rule allows DNS and NTP for internal clients:
 
 [.programlisting]
 ....
 udp_services = "{ domain, ntp }"
 pass quick inet proto { tcp, udp } to any port $udp_services keep state
 ....
 
 Note the `quick` keyword in this rule.
 Since the ruleset consists of several rules, it is important to understand the relationships between the rules in a ruleset.
 Rules are evaluated from top to bottom, in the sequence they are written.
 For each packet or connection evaluated by PF, _the last matching rule_ in the ruleset is the one which is applied.
 However, when a packet matches a rule which contains the `quick` keyword, the rule processing stops and the packet is treated according to that rule. 
 This is very useful when an exception to the general rules is needed.
 
 [[pftut-ftp]]
 ==== Creating an FTP Proxy
 
 Configuring working FTP rules can be problematic due to the nature of the FTP protocol.
 FTP pre-dates firewalls by several decades and is insecure in its design.
 The most common points against using FTP include:
 
 * Passwords are transferred in the clear.
 * The protocol demands the use of at least two TCP connections (control and data) on separate ports.
 * When a session is established, data is communicated using randomly selected ports.
 
 All of these points present security challenges, even before considering any potential security weaknesses in client or server software.
 More secure alternatives for file transfer exist, such as man:sftp[1] or man:scp[1], which both feature authentication and data transfer over encrypted connections..
 
 For those situations when FTP is required, PF provides redirection of FTP traffic to a small proxy program called man:ftp-proxy[8], which is included in the base system of FreeBSD.
 The role of the proxy is to dynamically insert and delete rules in the ruleset, using a set of anchors, to correctly handle FTP traffic.
 
 To enable the FTP proxy, add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 ftpproxy_enable="YES"
 ....
 
 Then start the proxy by running `service ftp-proxy start`.
 
 For a basic configuration, three elements need to be added to [.filename]#/etc/pf.conf#.
 First, the anchors which the proxy will use to insert the rules it generates for the FTP sessions:
 
 [.programlisting]
 ....
 nat-anchor "ftp-proxy/*"
 rdr-anchor "ftp-proxy/*"
 ....
 
 Second, a pass rule is needed to allow FTP traffic in to the proxy.
 
 Third, redirection and NAT rules need to be defined before the filtering rules.
 Insert this `rdr` rule immediately after the `nat` rule:
 
 [.programlisting]
 ....
 rdr pass on $int_if proto tcp from any to any port ftp -> 127.0.0.1 port 8021
 ....
 
 Finally, allow the redirected traffic to pass:
 
 [.programlisting]
 ....
 pass out proto tcp from $proxy to any port ftp
 ....
 
 where `$proxy` expands to the address the proxy daemon is bound to.
 
 Save [.filename]#/etc/pf.conf#, load the new rules, and verify from a client that FTP connections are working:
 
 [source,shell]
 ....
 # pfctl -f /etc/pf.conf
 ....
 
 This example covers a basic setup where the clients in the local network need to contact FTP servers elsewhere.
 This basic configuration should work well with most combinations of FTP clients and servers.
 As shown in man:ftp-proxy[8], the proxy's behavior can be changed in various ways by adding options to the `ftpproxy_flags=` line.
 Some clients or servers may have specific quirks that must be compensated for in the configuration, or there may be a need to integrate the proxy in specific ways such as assigning FTP traffic to a specific queue.
 
 For ways to run an FTP server protected by PF and man:ftp-proxy[8], configure a separate `ftp-proxy` in reverse mode, using `-R`, on a separate port with its own redirecting pass rule.
 
 [[pftut-icmp]]
 ==== Managing ICMP
 
 Many of the tools used for debugging or troubleshooting a TCP/IP network rely on the Internet Control Message Protocol (ICMP), which was designed specifically with debugging in mind.
 
 The ICMP protocol sends and receives _control messages_ between hosts and gateways, mainly to provide feedback to a sender about any unusual or difficult conditions enroute to the target host.
 Routers use ICMP to negotiate packet sizes and other transmission parameters in a process often referred to as _path MTU discovery_.
 
 From a firewall perspective, some ICMP control messages are vulnerable to known attack vectors.
 Also, letting all diagnostic traffic pass unconditionally makes debugging easier, but it also makes it easier for others to extract information about the network.
 For these reasons, the following rule may not be optimal:
 
 [.programlisting]
 ....
 pass inet proto icmp from any to any
 ....
 
 One solution is to let all ICMP traffic from the local network through while stopping all probes from outside the network:
 
 [.programlisting]
 ....
 pass inet proto icmp from $localnet to any keep state
 pass inet proto icmp from any to $ext_if keep state
 ....
 
 Additional options are available which demonstrate some of PF's flexibility.
 For example, rather than allowing all ICMP messages, one can specify the messages used by man:ping[8] and man:traceroute[8].
 Start by defining a macro for that type of message:
 
 [.programlisting]
 ....
 icmp_types = "echoreq"
 ....
 
 and a rule which uses the macro:
 
 [.programlisting]
 ....
 pass inet proto icmp all icmp-type $icmp_types keep state
 ....
 
 If other types of ICMP packets are needed, expand `icmp_types` to a list of those packet types.
 Type `more /usr/src/sbin/pfctl/pfctl_parser.c` to see the list of ICMP message types supported by PF.
 Refer to http://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml[http://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml] for an explanation of each message type.
 
 Since Unix `traceroute` uses UDP by default, another rule is needed to allow Unix `traceroute`:
 
 [.programlisting]
 ....
 # allow out the default range for traceroute(8):
 pass out on $ext_if inet proto udp from any to any port 33433 >< 33626 keep state
 ....
 
 Since `TRACERT.EXE` on Microsoft Windows systems uses ICMP echo request messages, only the first rule is needed to allow network traces from those systems.
 Unix `traceroute` can be instructed to use other protocols as well, and will use ICMP echo request messages if `-I` is used.
 Check the man:traceroute[8] man page for details.
 
 [[pftut-pathmtudisc]]
 ===== Path MTU Discovery
 
 Internet protocols are designed to be device independent, and one consequence of device independence is that the optimal packet size for a given connection cannot always be predicted reliably.
 The main constraint on packet size is the _Maximum Transmission Unit_ (MTU) which sets the upper limit on the packet size for an interface.
 Type `ifconfig` to view the MTUs for a system's network interfaces.
 
 TCP/IP uses a process known as path MTU discovery to determine the right packet size for a connection.
 This process sends packets of varying sizes with the "Do not fragment" flag set, expecting an ICMP return packet of "type 3, code 4" when the upper limit has been reached.
 Type 3 means "destination unreachable", and code 4 is short for "fragmentation needed, but the do-not-fragment flag is set".
 To allow path MTU discovery in order to support connections to other MTUs, add the `destination unreachable` type to the `icmp_types` macro:
 
 [.programlisting]
 ....
 icmp_types = "{ echoreq, unreach }"
 ....
 
 Since the pass rule already uses that macro, it does not need to be modified to support the new ICMP type:
 
 [.programlisting]
 ....
 pass inet proto icmp all icmp-type $icmp_types keep state
 ....
 
 PF allows filtering on all variations of ICMP types and codes.
 The list of possible types and codes are documented in man:icmp[4] and man:icmp6[4].
 
 [[pftut-tables]]
 ==== Using Tables
 
 Some types of data are relevant to filtering and redirection at a given time, but their definition is too long to be included in the ruleset file.
 PF supports the use of tables, which are defined lists that can be manipulated without needing to reload the entire ruleset, and which can provide fast lookups.
 Table names are always enclosed within `< >`, like this:
 
 [.programlisting]
 ....
 table <clients> { 192.168.2.0/24, !192.168.2.5 }
 ....
 
 In this example, the `192.168.2.0/24` network is part of the table, except for the address `192.168.2.5`, which is excluded using the `!` operator.
 It is also possible to load tables from files where each item is on a separate line, as seen in this example [.filename]#/etc/clients#:
 
 [.programlisting]
 ....
 192.168.2.0/24
 !192.168.2.5
 ....
 
 To refer to the file, define the table like this:
 
 [.programlisting]
 ....
 table <clients> persist file "/etc/clients"
 ....
 
 Once the table is defined, it can be referenced by a rule:
 
 [.programlisting]
 ....
 pass inet proto tcp from <clients> to any port $client_out flags S/SA keep state
 ....
 
 A table's contents can be manipulated live, using `pfctl`.
 This example adds another network to the table:
 
 [source,shell]
 ....
 # pfctl -t clients -T add 192.168.1.0/16
 ....
 
 Note that any changes made this way will take affect now, making them ideal for testing, but will not survive a power failure or reboot.
 To make the changes permanent, modify the definition of the table in the ruleset or edit the file that the table refers to.
 One can maintain the on-disk copy of the table using a man:cron[8] job which dumps the table's contents to disk at regular intervals, using a command such as `pfctl -t clients -T show >/etc/clients`.
 Alternatively, [.filename]#/etc/clients# can be updated with the in-memory table contents:
 
 [source,shell]
 ....
 # pfctl -t clients -T replace -f /etc/clients
 ....
 
 [[pftut-overload]]
 ==== Using Overload Tables to Protect SSH
 
 Those who run SSH on an external interface have probably seen something like this in the authentication logs:
 
 [.programlisting]
 ....
 Sep 26 03:12:34 skapet sshd[25771]: Failed password for root from 200.72.41.31 port 40992 ssh2
 Sep 26 03:12:34 skapet sshd[5279]: Failed password for root from 200.72.41.31 port 40992 ssh2
 Sep 26 03:12:35 skapet sshd[5279]: Received disconnect from 200.72.41.31: 11: Bye Bye
 Sep 26 03:12:44 skapet sshd[29635]: Invalid user admin from 200.72.41.31
 Sep 26 03:12:44 skapet sshd[24703]: input_userauth_request: invalid user admin
 Sep 26 03:12:44 skapet sshd[24703]: Failed password for invalid user admin from 200.72.41.31 port 41484 ssh2
 ....
 
 This is indicative of a brute force attack where somebody or some program is trying to discover the user name and password which will let them into the system.
 
 If external SSH access is needed for legitimate users, changing the default port used by SSH can offer some protection.
 However, PF provides a more elegant solution.
 Pass rules can contain limits on what connecting hosts can do and violators can be banished to a table of addresses which are denied some or all access. 
 It is even possible to drop all existing connections from machines which overreach the limits.
 
 To configure this, create this table in the tables section of the ruleset:
 
 [.programlisting]
 ....
 table <bruteforce> persist
 ....
 
 Then, somewhere early in the ruleset, add rules to block brute access while allowing legitimate access:
 
 [.programlisting]
 ....
 block quick from <bruteforce>
 pass inet proto tcp from any to $localnet port $tcp_services \
     flags S/SA keep state \
     (max-src-conn 100, max-src-conn-rate 15/5, \
     overload <bruteforce> flush global)
 ....
 
 The part in parentheses defines the limits and the numbers should be changed to meet local requirements.
 It can be read as follows:
 
 `max-src-conn` is the number of simultaneous connections allowed from one host.
 
 `max-src-conn-rate` is the rate of new connections allowed from any single host (_15_) per number of seconds (_5_).
 
 `overload <bruteforce>` means that any host which exceeds these limits gets its address added to the `bruteforce` table.
 The ruleset blocks all traffic from addresses in the `bruteforce` table.
 
 Finally, `flush global` says that when a host reaches the limit, that all (`global`) of that host's connections will be terminated (`flush`).
 
 [NOTE]
 ====
 These rules will _not_ block slow bruteforcers, as described in http://home.nuug.no/\~peter/hailmary2013/[http://home.nuug.no/~peter/hailmary2013/].
 ====
 
 This example ruleset is intended mainly as an illustration.
 For example, if a generous number of connections in general are wanted, but the desire is to be more restrictive when it comes to ssh, supplement the rule above with something like the one below, early on in the rule set:
 
 [.programlisting]
 ....
 pass quick proto { tcp, udp } from any to any port ssh \
     flags S/SA keep state \
     (max-src-conn 15, max-src-conn-rate 5/3, \
     overload <bruteforce> flush global)
 ....
 
 [NOTE]
 ====
 *It May Not be Necessary to Block All Overloaders:* +
 
 It is worth noting that the overload mechanism is a general technique which does not apply exclusively to SSH, and it is not always optimal to entirely block all traffic from offenders.
 
 For example, an overload rule could be used to protect a mail service or a web service, and the overload table could be used in a rule to assign offenders to a queue with a minimal bandwidth allocation or to redirect to a specific web page.
 ====
 
 Over time, tables will be filled by overload rules and their size will grow incrementally, taking up more memory.
 Sometimes an IP address that is blocked is a dynamically assigned one, which has since been assigned to a host who has a legitimate reason to communicate with hosts in the local network.
 
 For situations like these, pfctl provides the ability to expire table entries.
 For example, this command will remove `<bruteforce>` table entries which have not been referenced for `86400` seconds:
 
 [source,shell]
 ....
 # pfctl -t bruteforce -T expire 86400
 ....
 
 Similar functionality is provided by package:security/expiretable[], which removes table entries which have not been accessed for a specified period of time.
 
 Once installed, expiretable can be run to remove `<bruteforce>` table entries older than a specified age.
 This example removes all entries older than 24 hours:
 
 [.programlisting]
 ....
 /usr/local/sbin/expiretable -v -d -t 24h bruteforce
 ....
 
 [[pftut-spamd]]
 ==== Protecting Against SPAM
 
 Not to be confused with the spamd daemon which comes bundled with spamassassin, package:mail/spamd[] can be configured with PF to provide an outer defense against SPAM.
 This spamd hooks into the PF configuration using a set of redirections.
 
 Spammers tend to send a large number of messages, and SPAM is mainly sent from a few spammer friendly networks and a large number of hijacked machines, both of which are reported to _blacklists_ fairly quickly.
 
 When an SMTP connection from an address in a blacklist is received, spamd presents its banner and immediately switches to a mode where it answers SMTP traffic one byte at a time.
 This technique, which is intended to waste as much time as possible on the spammer's end, is called _tarpitting_.
 The specific implementation which uses one byte SMTP replies is often referred to as _stuttering_.
 
 This example demonstrates the basic procedure for setting up spamd with automatically updated blacklists.
 Refer to the man pages which are installed with package:mail/spamd[] for more information.
 
 [.procedure]
 ****
 .Procedure: Configuring spamd
 . Install the package:mail/spamd[] package or port. To use spamd's greylisting features, man:fdescfs[5] must be mounted at [.filename]#/dev/fd#. Add the following line to [.filename]#/etc/fstab#:
 +
 [.programlisting]
 ....
  fdescfs /dev/fd fdescfs rw 0 0
 ....
-+ 
++
 Then, mount the filesystem:
 +
 [.programlisting]
 ....
 #  mount fdescfs
 ....
 
 . Next, edit the PF ruleset to include:
 +
 [.programlisting]
 ....
 table <spamd> persist
 table <spamd-white> persist
 rdr pass on $ext_if inet proto tcp from <spamd> to \
     { $ext_if, $localnet } port smtp -> 127.0.0.1 port 8025
 rdr pass on $ext_if inet proto tcp from !<spamd-white> to \
     { $ext_if, $localnet } port smtp -> 127.0.0.1 port 8025
 ....
-+ 
++
 The two tables `<spamd>` and `<spamd-white>` are essential.
 SMTP traffic from an address listed in `<spamd>` but not in `<spamd-white>` is redirected to the spamd daemon listening at port 8025.
 . The next step is to configure spamd in [.filename]#/usr/local/etc/spamd.conf# and to add some [.filename]#rc.conf# parameters.
-+ 
++
 The installation of package:mail/spamd[] includes a sample configuration file ([.filename]#/usr/local/etc/spamd.conf.sample#) and a man page for [.filename]#spamd.conf#.
 Refer to these for additional configuration options beyond those shown in this example.
-+ 
++
 One of the first lines in the configuration file that does not begin with a `#` comment sign contains the block which defines the `all` list, which specifies the lists to use:
 +
 [.programlisting]
 ....
 all:\
     :traplist:whitelist:
 ....
-+ 
++
 This entry adds the desired blacklists, separated by colons (`:`).
 To use a whitelist to subtract addresses from a blacklist, add the name of the whitelist _immediately_ after the name of that blacklist. For example: `:blacklist:whitelist:`.
-+ 
++
 This is followed by the specified blacklist's definition:
 +
 [.programlisting]
 ....
 traplist:\
     :black:\
     :msg="SPAM. Your address %A has sent spam within the last 24 hours":\
     :method=http:\
     :file=www.openbsd.org/spamd/traplist.gz
 ....
-+ 
++
 where the first line is the name of the blacklist and the second line specifies the list type.
 The `msg` field contains the message to display to blacklisted senders during the SMTP dialogue.
 The `method` field specifies how spamd-setup fetches the list data; supported methods are `http`, `ftp`, from a `file` in a mounted file system, and via `exec` of an external program.
 Finally, the `file` field specifies the name of the file spamd expects to receive.
-+ 
++
 The definition of the specified whitelist is similar, but omits the `msg` field since a message is not needed:
 +
 [.programlisting]
 ....
 whitelist:\
     :white:\
     :method=file:\
     :file=/var/mail/whitelist.txt
 ....
 +
 [TIP]
 ====
 *Choose Data Sources with Care:* +
 
 Using all the blacklists in the sample [.filename]#spamd.conf# will blacklist large blocks of the Internet.
 Administrators need to edit the file to create an optimal configuration which uses applicable data sources and, when necessary, uses custom lists.
 ====
-+ 
++
 Next, add this entry to [.filename]#/etc/rc.conf#.
 Additional flags are described in the man page specified by the comment:
 +
 [.programlisting]
 ....
 spamd_flags="-v" # use "" and see spamd-setup(8) for flags
 ....
-+ 
++
 When finished, reload the ruleset, start spamd by typing `service obspamd start`, and complete the configuration using `spamd-setup`.
 Finally, create a man:cron[8] job which calls `spamd-setup` to update the tables at reasonable intervals.
 ****
 
 On a typical gateway in front of a mail server, hosts will soon start getting trapped within a few seconds to several minutes.
 
 PF also supports _greylisting_, which temporarily rejects messages from unknown hosts with _45n_ codes.
 Messages from greylisted hosts which try again within a reasonable time are let through.
 Traffic from senders which are set up to behave within the limits set by RFC 1123 and RFC 2821 are immediately let through.
 
 More information about greylisting as a technique can be found at the http://www.greylisting.org/[greylisting.org] web site.
 The most amazing thing about greylisting, apart from its simplicity, is that it still works.
 Spammers and malware writers have been very slow to adapt to bypass this technique.
 
 The basic procedure for configuring greylisting is as follows:
 
 [.procedure]
 .Procedure: Configuring Greylisting
 . Make sure that man:fdescfs[5] is mounted as described in Step 1 of the previous Procedure.
 . To run spamd in greylisting mode, add this line to [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 spamd_grey="YES"  # use spamd greylisting if YES
 ....
-+ 
++
 Refer to the spamd man page for descriptions of additional related parameters.
 . To complete the greylisting setup:
 +
 [.programlisting]
 ....
 #  service obspamd restart
 #  service obspamlogd start
 ....
 
 Behind the scenes, the spamdb database tool and the spamlogd whitelist updater perform essential functions for the greylisting feature.
 spamdb is the administrator's main interface to managing the black, grey, and white lists via the contents of the [.filename]#/var/db/spamdb# database.
 
 [[pftut-hygiene]]
 ==== Network Hygiene
 
 This section describes how `block-policy`, `scrub`, and `antispoof` can be used to make the ruleset behave sanely.
 
 The `block-policy` is an option which can be set in the `options` part of the ruleset, which precedes the redirection and filtering rules.
 This option determines which feedback, if any, PF sends to hosts that are blocked by a rule.
 The option has two possible values: `drop` drops blocked packets with no feedback, and `return` returns a status code such as `Connection refused`.
 
 If not set, the default policy is `drop`.
 To change the `block-policy`, specify the desired value:
 
 [.programlisting]
 ....
 set block-policy return
 ....
 
 In PF, `scrub` is a keyword which enables network packet normalization.
 This process reassembles fragmented packets and drops TCP packets that have invalid flag combinations.
 Enabling `scrub` provides a measure of protection against certain kinds of attacks based on incorrect handling of packet fragments.
 A number of options are available, but the simplest form is suitable for most configurations:
 
 [.programlisting]
 ....
 scrub in all
 ....
 
 Some services, such as NFS, require specific fragment handling options.
 Refer to https://home.nuug.no/\~peter/pf/en/scrub.html[https://home.nuug.no/~peter/pf/en/scrub.html] for more information.
 
 This example reassembles fragments, clears the "do not fragment" bit, and sets the maximum segment size to 1440 bytes:
 
 [.programlisting]
 ....
 scrub in all fragment reassemble no-df max-mss 1440
 ....
 
 The `antispoof` mechanism protects against activity from spoofed or forged IP addresses, mainly by blocking packets appearing on interfaces and in directions which are logically not possible.
 
 These rules weed out spoofed traffic coming in from the rest of the world as well as any spoofed packets which originate in the local network:
 
 [.programlisting]
 ....
 antispoof for $ext_if
 antispoof for $int_if
 ....
 
 [[pftut-unrouteables]]
 ==== Handling Non-Routable Addresses
 
 Even with a properly configured gateway to handle network address translation, one may have to compensate for other people's misconfigurations.
 A common misconfiguration is to let traffic with non-routable addresses out to the Internet.
 Since traffic from non-routeable addresses can play a part in several DoS attack techniques, consider explicitly blocking traffic from non-routeable addresses from entering the network through the external interface.
 
 In this example, a macro containing non-routable addresses is defined, then used in blocking rules.
 Traffic to and from these addresses is quietly dropped on the gateway's external interface.
 
 [.programlisting]
 ....
 martians = "{ 127.0.0.0/8, 192.168.0.0/16, 172.16.0.0/12, \
 	      10.0.0.0/8, 169.254.0.0/16, 192.0.2.0/24, \
 	      0.0.0.0/8, 240.0.0.0/4 }"
 
 block drop in quick on $ext_if from $martians to any
 block drop out quick on $ext_if from any to $martians
 ....
 
 === Enabling ALTQ
 
 On FreeBSD, ALTQ can be used with PF to provide Quality of Service (QOS).
 Once ALTQ is enabled, queues can be defined in the ruleset which determine the processing priority of outbound packets.
 
 Before enabling ALTQ, refer to man:altq[4] to determine if the drivers for the network cards installed on the system support it.
 
 ALTQ is not available as a loadable kernel module.
 If the system's interfaces support ALTQ, create a custom kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel].
 The following kernel options are available.
 The first is needed to enable ALTQ.
 At least one of the other options is necessary to specify the queueing scheduler algorithm:
 
 [.programlisting]
 ....
 options         ALTQ
 options         ALTQ_CBQ        # Class Based Queuing (CBQ)
 options         ALTQ_RED        # Random Early Detection (RED)
 options         ALTQ_RIO        # RED In/Out
 options         ALTQ_HFSC       # Hierarchical Packet Scheduler (HFSC)
 options         ALTQ_PRIQ       # Priority Queuing (PRIQ)
 ....
 
 The following scheduler algorithms are available:
 
 CBQ::
 Class Based Queuing (CBQ) is used to divide a connection's bandwidth into different classes or queues to prioritize traffic based on filter rules.
 
 RED::
 Random Early Detection (RED) is used to avoid network congestion by measuring the length of the queue and comparing it to the minimum and maximum thresholds for the queue.
 When the queue is over the maximum, all new packets are randomly dropped.
 
 RIO::
 In Random Early Detection In and Out (RIO) mode, RED maintains multiple average queue lengths and multiple threshold values, one for each QOS level.
 
 HFSC::
 Hierarchical Fair Service Curve Packet Scheduler (HFSC) is described in http://www-2.cs.cmu.edu/\~hzhang/HFSC/main.html[http://www-2.cs.cmu.edu/~hzhang/HFSC/main.html].
 
 PRIQ::
 Priority Queuing (PRIQ) always passes traffic that is in a higher queue first.
 
 More information about the scheduling algorithms and example rulesets are available at the https://web.archive.org/web/20151109213426/http://www.openbsd.org/faq/pf/queueing.html[OpenBSD's web archive].
 
 [[firewalls-ipfw]]
 == IPFW
 
 IPFW is a stateful firewall written for FreeBSD which supports both IPv4 and IPv6.
 It is comprised of several components: the kernel firewall filter rule processor and its integrated packet accounting facility, the logging facility, NAT, the man:dummynet[4] traffic shaper, a forward facility, a bridge facility, and an ipstealth facility.
 
 FreeBSD provides a sample ruleset in [.filename]#/etc/rc.firewall# which defines several firewall types for common scenarios to assist novice users in generating an appropriate ruleset.
 IPFW provides a powerful syntax which advanced users can use to craft customized rulesets that meet the security requirements of a given environment.
 
 This section describes how to enable IPFW, provides an overview of its rule syntax, and demonstrates several rulesets for common configuration scenarios.
 
 [[firewalls-ipfw-enable]]
 === Enabling IPFW
 
 IPFW is included in the basic FreeBSD install as a kernel loadable module, meaning that a custom kernel is not needed in order to enable IPFW.
 
 For those users who wish to statically compile IPFW support into a custom kernel, see <<firewalls-ipfw-kernelconfig>>.
 
 To configure the system to enable IPFW at boot time, add `firewall_enable="YES"` to [.filename]#/etc/rc.conf#:
 
 [source,shell]
 ....
 # sysrc firewall_enable="YES"
 ....
 
 To use one of the default firewall types provided by FreeBSD, add another line which specifies the type:
 
 [source,shell]
 ....
 # sysrc firewall_type="open"
 ....
 
 The available types are:
 
 * `open`: passes all traffic.
 * `client`: protects only this machine.
 * `simple`: protects the whole network.
 * `closed`: entirely disables IP traffic except for the loopback interface.
 * `workstation`: protects only this machine using stateful rules.
 * `UNKNOWN`: disables the loading of firewall rules.
 * [.filename]#filename#: full path of the file containing the firewall ruleset.
 
 If `firewall_type` is set to either `client` or `simple`, modify the default rules found in [.filename]#/etc/rc.firewall# to fit the configuration of the system.
 
 Note that the `filename` type is used to load a custom ruleset.
 
 An alternate way to load a custom ruleset is to set the `firewall_script` variable to the absolute path of an _executable script_ that includes IPFW commands.
 The examples used in this section assume that the `firewall_script` is set to [.filename]#/etc/ipfw.rules#:
 
 [source,shell]
 ....
 # sysrc firewall_script="/etc/ipfw.rules"
 ....
 
 To enable logging through man:syslogd[8], include this line:
 
 [source,shell]
 ....
 # sysrc firewall_logging="YES"
 ....
 
 [WARNING]
 ====
 Only firewall rules with the `log` option will be logged.
 The default rules do not include this option and it must be manually added.
 Therefore it is advisable that the default ruleset is edited for logging.
 In addition, log rotation may be desired if the logs are stored in a separate file.
 ====
 
 There is no [.filename]#/etc/rc.conf# variable to set logging limits.
 To limit the number of times a rule is logged per connection attempt, specify the number using this line in [.filename]#/etc/sysctl.conf#:
 
 [source,shell]
 ....
 # echo "net.inet.ip.fw.verbose_limit=5" >> /etc/sysctl.conf
 ....
 
 To enable logging through a dedicated interface named `ipfw0`, add this line to [.filename]#/etc/rc.conf# instead:
 
 [source,shell]
 ....
 # sysrc firewall_logif="YES"
 ....
 
 Then use tcpdump to see what is being logged:
 
 [source,shell]
 ....
 # tcpdump -t -n -i ipfw0
 ....
 
 [TIP]
 ====
 
 There is no overhead due to logging unless tcpdump is attached.
 ====
 
 After saving the needed edits, start the firewall.
 To enable logging limits now, also set the `sysctl` value specified above:
 
 [source,shell]
 ....
 # service ipfw start
 # sysctl net.inet.ip.fw.verbose_limit=5
 ....
 
 [[firewalls-ipfw-rules]]
 === IPFW Rule Syntax
 
 When a packet enters the IPFW firewall, it is compared against the first rule in the ruleset and progresses one rule at a time, moving from top to bottom in sequence.
 When the packet matches the selection parameters of a rule, the rule's action is executed and the search of the ruleset terminates for that packet.
 This is referred to as "first match wins".
 If the packet does not match any of the rules, it gets caught by the mandatory IPFW default rule number 65535, which denies all packets and silently discards them.
 However, if the packet matches a rule that contains the `count`, `skipto`, or `tee` keywords, the search continues.
 Refer to man:ipfw[8] for details on how these keywords affect rule processing.
 
 When creating an IPFW rule, keywords must be written in the following order.
 Some keywords are mandatory while other keywords are optional.
 The words shown in uppercase represent a variable and the words shown in lowercase must precede the variable that follows it.
 The `#` symbol is used to mark the start of a comment and may appear at the end of a rule or on its own line.
 Blank lines are ignored.
 
 `_CMD RULE_NUMBER set SET_NUMBER ACTION log LOG_AMOUNT PROTO from SRC SRC_PORT to DST DST_PORT OPTIONS_`
 
 This section provides an overview of these keywords and their options.
 It is not an exhaustive list of every possible option.
 Refer to man:ipfw[8] for a complete description of the rule syntax that can be used when creating IPFW rules.
 
 CMD::
 Every rule must start with `ipfw add`.
 
 RULE_NUMBER::
 Each rule is associated with a number from `1` to `65534`.
 The number is used to indicate the order of rule processing.
 Multiple rules can have the same number, in which case they are applied according to the order in which they have been added.
 
 SET_NUMBER::
 Each rule is associated with a set number from `0` to `31`.
 Sets can be individually disabled or enabled, making it possible to quickly add or delete a set of rules.
 If a SET_NUMBER is not specified, the rule will be added to set `0`.
 
 ACTION::
 A rule can be associated with one of the following actions.
 The specified action will be executed when the packet matches the selection criterion of the rule.
 +
 `allow | accept | pass | permit`: these keywords are equivalent and allow packets that match the rule.
 +
 `check-state`: checks the packet against the dynamic state table.
 If a match is found, execute the action associated with the rule which generated this dynamic rule, otherwise move to the next rule.
 A `check-state` rule does not have selection criterion.
 If no `check-state` rule is present in the ruleset, the dynamic rules table is checked at the first `keep-state` or `limit` rule.
 +
 `count`: updates counters for all packets that match the rule.
 The search continues with the next rule.
 +
 `deny | drop`: either word silently discards packets that match this rule.
 +
 Additional actions are available.
 Refer to man:ipfw[8] for details.
 
 LOG_AMOUNT::
 When a packet matches a rule with the `log` keyword, a message will be logged to man:syslogd[8] with a facility name of `SECURITY`.
 Logging only occurs if the number of packets logged for that particular rule does not exceed a specified LOG_AMOUNT.
 If no LOG_AMOUNT is specified, the limit is taken from the value of `net.inet.ip.fw.verbose_limit`.
 A value of zero removes the logging limit.
 Once the limit is reached, logging can be re-enabled by clearing the logging counter or the packet counter for that rule, using `ipfw resetlog`.
 +
 [NOTE]
 ====
 Logging is done after all other packet matching conditions have been met, and before performing the final action on the packet.
 The administrator decides which rules to enable logging on.
 ====
 
 PROTO::
 This optional value can be used to specify any protocol name or number found in [.filename]#/etc/protocols#.
 
 SRC::
 The `from` keyword must be followed by the source address or a keyword that represents the source address.
 An address can be represented by `any`, `me` (any address configured on an interface on this system), `me6`, (any IPv6 address configured on an interface on this system), or `table` followed by the number of a lookup table which contains a list of addresses.
 When specifying an IP address, it can be optionally followed by its CIDR mask or subnet mask.
 For example, `1.2.3.4/25` or `1.2.3.4:255.255.255.128`.
 
 SRC_PORT::
 An optional source port can be specified using the port number or name from [.filename]#/etc/services#.
 
 DST::
 The `to` keyword must be followed by the destination address or a keyword that represents the destination address.
 The same keywords and addresses described in the SRC section can be used to describe the destination.
 
 DST_PORT::
 An optional destination port can be specified using the port number or name from [.filename]#/etc/services#.
 
 OPTIONS::
 Several keywords can follow the source and destination.
 As the name suggests, OPTIONS are optional.
 Commonly used options include `in` or `out`, which specify the direction of packet flow, `icmptypes` followed by the type of ICMP message, and `keep-state`.
 +
 When a `keep-state` rule is matched, the firewall will create a dynamic rule which matches bidirectional traffic between the source and destination addresses and ports using the same protocol.
 +
 The dynamic rules facility is vulnerable to resource depletion from a SYN-flood attack which would open a huge number of dynamic rules.
 To counter this type of attack with IPFW, use `limit`.
 This option limits the number of simultaneous sessions by checking the open dynamic rules, counting the number of times this rule and IP address combination occurred.
 If this count is greater than the value specified by `limit`, the packet is discarded.
 +
 Dozens of OPTIONS are available.
 Refer to man:ipfw[8] for a description of each available option.
 
 === Example Ruleset
 
 This section demonstrates how to create an example stateful firewall ruleset script named [.filename]#/etc/ipfw.rules#.
 In this example, all connection rules use `in` or `out` to clarify the direction.
 They also use `via` _interface-name_ to specify the interface the packet is traveling over.
 
 [NOTE]
 ====
 When first creating or testing a firewall ruleset, consider temporarily setting this tunable:
 
 [.programlisting]
 ....
 net.inet.ip.fw.default_to_accept="1"
 ....
 
 This sets the default policy of man:ipfw[8] to be more permissive than the default `deny ip from any to any`, making it slightly more difficult to get locked out of the system right after a reboot.
 ====
 
 The firewall script begins by indicating that it is a Bourne shell script and flushes any existing rules.
 It then creates the `cmd` variable so that `ipfw add` does not have to be typed at the beginning of every rule.
 It also defines the `pif` variable which represents the name of the interface that is attached to the Internet.
 
 [.programlisting]
 ....
 #!/bin/sh
 # Flush out the list before we begin.
 ipfw -q -f flush
 
 # Set rules command prefix
 cmd="ipfw -q add"
 pif="dc0"     # interface name of NIC attached to Internet
 ....
 
 The first two rules allow all traffic on the trusted internal interface and on the loopback interface:
 
 [.programlisting]
 ....
 # Change xl0 to LAN NIC interface name
 $cmd 00005 allow all from any to any via xl0
 
 # No restrictions on Loopback Interface
 $cmd 00010 allow all from any to any via lo0
 ....
 
 The next rule allows the packet through if it matches an existing entry in the dynamic rules table:
 
 [.programlisting]
 ....
 $cmd 00101 check-state
 ....
 
 The next set of rules defines which stateful connections internal systems can create to hosts on the Internet:
 
 [.programlisting]
 ....
 # Allow access to public DNS
 # Replace x.x.x.x with the IP address of a public DNS server
 # and repeat for each DNS server in /etc/resolv.conf
 $cmd 00110 allow tcp from any to x.x.x.x 53 out via $pif setup keep-state
 $cmd 00111 allow udp from any to x.x.x.x 53 out via $pif keep-state
 
 # Allow access to ISP's DHCP server for cable/DSL configurations.
 # Use the first rule and check log for IP address.
 # Then, uncomment the second rule, input the IP address, and delete the first rule
 $cmd 00120 allow log udp from any to any 67 out via $pif keep-state
 #$cmd 00120 allow udp from any to x.x.x.x 67 out via $pif keep-state
 
 # Allow outbound HTTP and HTTPS connections
 $cmd 00200 allow tcp from any to any 80 out via $pif setup keep-state
 $cmd 00220 allow tcp from any to any 443 out via $pif setup keep-state
 
 # Allow outbound email connections
 $cmd 00230 allow tcp from any to any 25 out via $pif setup keep-state
 $cmd 00231 allow tcp from any to any 110 out via $pif setup keep-state
 
 # Allow outbound ping
 $cmd 00250 allow icmp from any to any out via $pif keep-state
 
 # Allow outbound NTP
 $cmd 00260 allow udp from any to any 123 out via $pif keep-state
 
 # Allow outbound SSH
 $cmd 00280 allow tcp from any to any 22 out via $pif setup keep-state
 
 # deny and log all other outbound connections
 $cmd 00299 deny log all from any to any out via $pif
 ....
 
 The next set of rules controls connections from Internet hosts to the internal network.
 It starts by denying packets typically associated with attacks and then explicitly allows specific types of connections.
 All the authorized services that originate from the Internet use `limit` to prevent flooding.
 
 [.programlisting]
 ....
 # Deny all inbound traffic from non-routable reserved address spaces
 $cmd 00300 deny all from 192.168.0.0/16 to any in via $pif     #RFC 1918 private IP
 $cmd 00301 deny all from 172.16.0.0/12 to any in via $pif      #RFC 1918 private IP
 $cmd 00302 deny all from 10.0.0.0/8 to any in via $pif         #RFC 1918 private IP
 $cmd 00303 deny all from 127.0.0.0/8 to any in via $pif        #loopback
 $cmd 00304 deny all from 0.0.0.0/8 to any in via $pif          #loopback
 $cmd 00305 deny all from 169.254.0.0/16 to any in via $pif     #DHCP auto-config
 $cmd 00306 deny all from 192.0.2.0/24 to any in via $pif       #reserved for docs
 $cmd 00307 deny all from 204.152.64.0/23 to any in via $pif    #Sun cluster interconnect
 $cmd 00308 deny all from 224.0.0.0/3 to any in via $pif        #Class D & E multicast
 
 # Deny public pings
 $cmd 00310 deny icmp from any to any in via $pif
 
 # Deny ident
 $cmd 00315 deny tcp from any to any 113 in via $pif
 
 # Deny all Netbios services.
 $cmd 00320 deny tcp from any to any 137 in via $pif
 $cmd 00321 deny tcp from any to any 138 in via $pif
 $cmd 00322 deny tcp from any to any 139 in via $pif
 $cmd 00323 deny tcp from any to any 81 in via $pif
 
 # Deny fragments
 $cmd 00330 deny all from any to any frag in via $pif
 
 # Deny ACK packets that did not match the dynamic rule table
 $cmd 00332 deny tcp from any to any established in via $pif
 
 # Allow traffic from ISP's DHCP server.
 # Replace x.x.x.x with the same IP address used in rule 00120.
 #$cmd 00360 allow udp from any to x.x.x.x 67 in via $pif keep-state
 
 # Allow HTTP connections to internal web server
 $cmd 00400 allow tcp from any to me 80 in via $pif setup limit src-addr 2
 
 # Allow inbound SSH connections
 $cmd 00410 allow tcp from any to me 22 in via $pif setup limit src-addr 2
 
 # Reject and log all other incoming connections
 $cmd 00499 deny log all from any to any in via $pif
 ....
 
 The last rule logs all packets that do not match any of the rules in the ruleset:
 
 [.programlisting]
 ....
 # Everything else is denied and logged
 $cmd 00999 deny log all from any to any
 ....
 
 [[in-kernel-nat]]
 === In-kernel NAT
 
 FreeBSD's IPFW firewall has two implementations of NAT: the userland implementation man:natd[8], and the more recent in-kernel NAT implementation. 
 Both work in conjunction with IPFW to provide network address translation.
 This can be used to provide an Internet Connection Sharing solution so that several internal computers can connect to the Internet using a single public IP address.
 
 To do this, the FreeBSD machine connected to the Internet must act as a gateway.
 This system must have two NICs, where one is connected to the Internet and the other is connected to the internal LAN.
 Each machine connected to the LAN should be assigned an IP address in the private network space, as defined by https://www.ietf.org/rfc/rfc1918.txt[RFC 1918].
 
 Some additional configuration is needed in order to enable the in-kernel NAT facility of IPFW.
 To enable in-kernel NAT support at boot time, the following must be set in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 gateway_enable="YES"
 firewall_enable="YES"
 firewall_nat_enable="YES"
 ....
 
 [NOTE]
 ====
 When `firewall_nat_enable` is set but `firewall_enable` is not, it will have no effect and do nothing.
 This is because the in-kernel NAT implementation is only compatible with IPFW.
 ====
 
 When the ruleset contains stateful rules, the positioning of the NAT rule is critical and the `skipto` action is used.
 The `skipto` action requires a rule number so that it knows which rule to jump to.
 The example below builds upon the firewall ruleset shown in the previous section.
 It adds some additional entries and modifies some existing rules in order to configure the firewall for in-kernel NAT.
 It starts by adding some additional variables which represent the rule number to skip to, the `keep-state` option, and a list of TCP ports which will be used to reduce the number of rules.
 
 [.programlisting]
 ....
 #!/bin/sh
 ipfw -q -f flush
 cmd="ipfw -q add"
 skip="skipto 1000"
 pif=dc0
 ks="keep-state"
 good_tcpo="22,25,37,53,80,443,110"
 ....
 
 With in-kernel NAT it is necessary to disable TCP segmentation offloading (TSO) due to the architecture of man:libalias[3], a library implemented as a kernel module to provide the in-kernel NAT facility of IPFW.
 TSO can be disabled on a per network interface basis using man:ifconfig[8] or on a system wide basis using man:sysctl[8].
 To disable TSO system wide, the following must be set it [.filename]#/etc/sysctl.conf#:
 
 [.programlisting]
 ....
 net.inet.tcp.tso="0"
 ....
 
 A NAT instance will also be configured.
 It is possible to have multiple NAT instances each with their own configuration.
 For this example only one NAT instance is needed, NAT instance number 1.
 The configuration can take a few options such as: `if` which indicates the public interface, `same_ports` which takes care that alliased ports and local port numbers are mapped the same, `unreg_only` will result in only unregistered (private) address spaces to be processed by the NAT instance, and `reset` which will help to keep a functioning NAT instance even when the public IP address of the IPFW machine changes.
 For all possible options that can be passed to a single NAT instance configuration consult man:ipfw[8].
 When configuring a stateful NATing firewall, it is necessary to allow translated packets to be reinjected in the firewall for further processing.
 This can be achieved by disabling `one_pass` behavior at the start of the firewall script.
 
 [.programlisting]
 ....
 ipfw disable one_pass
 ipfw -q nat 1 config if $pif same_ports unreg_only reset
 ....
 
 The inbound NAT rule is inserted _after_ the two rules which allow all traffic on the trusted and loopback interfaces and after the reassemble rule but _before_ the `check-state` rule.
 It is important that the rule number selected for this NAT rule, in this example `100`, is higher than the first three rules and lower than the `check-state` rule.
 Furthermore, because of the behavior of in-kernel NAT it is advised to place a reassemble rule just before the first NAT rule and after the rules that allow traffic on trusted interface.
 Normally, IP fragmentation should not happen, but when dealing with IPSEC/ESP/GRE tunneling traffic it might and the reassembling of fragments is necessary before handing the complete packet over to the in-kernel NAT facility.
 
 [NOTE]
 ====
 The reassemble rule was not needed with userland man:natd[8] because the internal workings of the IPFW `divert` action already takes care of reassembling packets before delivery to the socket as also stated in man:ipfw[8].
 
 The NAT instance and rule number used in this example does not match with the default NAT instance and rule number created by [.filename]#rc.firewall#.
 [.filename]#rc.firewall# is a script that sets up the default firewall rules present in FreeBSD.
 ====
 
 [.programlisting]
 ....
 $cmd 005 allow all from any to any via xl0  # exclude LAN traffic
 $cmd 010 allow all from any to any via lo0  # exclude loopback traffic
 $cmd 099 reass all from any to any in       # reassemble inbound packets
 $cmd 100 nat 1 ip from any to any in via $pif # NAT any inbound packets
 # Allow the packet through if it has an existing entry in the dynamic rules table
 $cmd 101 check-state
 ....
 
 The outbound rules are modified to replace the `allow` action with the `$skip` variable, indicating that rule processing will continue at rule `1000`.
 The seven `tcp` rules have been replaced by rule `125` as the `$good_tcpo` variable contains the seven allowed outbound ports.
 
 [NOTE]
 ====
 Remember that IPFW's performance is largely determined by the number of rules present in the ruleset.
 ====
 
 [.programlisting]
 ....
 # Authorized outbound packets
 $cmd 120 $skip udp from any to x.x.x.x 53 out via $pif $ks
 $cmd 121 $skip udp from any to x.x.x.x 67 out via $pif $ks
 $cmd 125 $skip tcp from any to any $good_tcpo out via $pif setup $ks
 $cmd 130 $skip icmp from any to any out via $pif $ks
 ....
 
 The inbound rules remain the same, except for the very last rule which removes the `via $pif` in order to catch both inbound and outbound rules.
 The NAT rule must follow this last outbound rule, must have a higher number than that last rule, and the rule number must be referenced by the `skipto` action.
 In this ruleset, rule number `1000` handles passing all packets to our configured instance for NAT processing.
 The next rule allows any packet which has undergone NAT processing to pass.
 
 [.programlisting]
 ....
 $cmd 999 deny log all from any to any
 $cmd 1000 nat 1 ip from any to any out via $pif # skipto location for outbound stateful rules
 $cmd 1001 allow ip from any to any
 ....
 
 In this example, rules `100`, `101`, `125`, `1000`, and `1001` control the address translation of the outbound and inbound packets so that the entries in the dynamic state table always register the private LANIP address.
 
 Consider an internal web browser which initializes a new outbound HTTP session over port 80.
 When the first outbound packet enters the firewall, it does not match rule `100` because it is headed out rather than in.
 It passes rule `101` because this is the first packet and it has not been posted to the dynamic state table yet.
 The packet finally matches rule `125` as it is outbound on an allowed port and has a source IP address from the internal LAN.
 On matching this rule, two actions take place.
 First, the `keep-state` action adds an entry to the dynamic state table and the specified action, `skipto rule 1000`, is executed.
 Next, the packet undergoes NAT and is sent out to the Internet.
 This packet makes its way to the destination web server, where a response packet is generated and sent back.
 This new packet enters the top of the ruleset.
 It matches rule `100` and has its destination IP address mapped back to the original internal address.
 It then is processed by the `check-state` rule, is found in the table as an existing session, and is released to the LAN.
 
 On the inbound side, the ruleset has to deny bad packets and allow only authorized services.
 A packet which matches an inbound rule is posted to the dynamic state table and the packet is released to the LAN.
 The packet generated as a response is recognized by the `check-state` rule as belonging to an existing session.
 It is then sent to rule `1000` to undergo NAT before being released to the outbound interface.
 
 [NOTE]
 ====
 Transitioning from userland man:natd[8] to in-kernel NAT might appear seamless at first but there is small catch.
 When using the GENERIC kernel, IPFW will load the [.filename]#libalias.ko# kernel module, when `firewall_nat_enable` is enabled in [.filename]#/etc/rc.conf#.
 The [.filename]#libalias.ko# kernel module only provides basic NAT functionality, whereas the userland implementation man:natd[8] has all NAT functionality available in its userland library without any extra configuration.
 All functionality refers to the following kernel modules that can additionally be loaded when needed besides the standard [.filename]#libalias.ko# kernel module: [.filename]#alias_ftp.ko#, [.filename]#alias_bbt.ko#, [.filename]#skinny.ko#, [.filename]#irc.ko#, [.filename]#alias_pptp.ko# and [.filename]#alias_smedia.ko# using the `kld_list` directive in [.filename]#/etc/rc.conf#.
 If a custom kernel is used, the full functionality of the userland library can be compiled in, in the kernel, using the `options LIBALIAS`.
 ====
 
 ==== Port Redirection
 
 The drawback with NAT in general is that the LAN clients are not accessible from the Internet.
 Clients on the LAN can make outgoing connections to the world but cannot receive incoming ones.
 This presents a problem if trying to run Internet services on one of the LAN client machines.
 A simple way around this is to redirect selected Internet ports on the NAT providing machine to a LAN client.
 
 For example, an IRC server runs on client `A` and a web server runs on client `B`.
 For this to work properly, connections received on ports 6667 (IRC) and 80 (HTTP) must be redirected to the respective machines.
 
 With in-kernel NAT all configuration is done in the NAT instance configuration.
 For a full list of options that an in-kernel NAT instance can use, consult man:ipfw[8].
 The IPFW syntax follows the syntax of natd. The syntax for `redirect_port` is as follows:
 
 [.programlisting]
 ....
 redirect_port proto targetIP:targetPORT[-targetPORT]
   [aliasIP:]aliasPORT[-aliasPORT]
   [remoteIP[:remotePORT[-remotePORT]]]
 ....
 
 To configure the above example setup, the arguments should be:
 
 [.programlisting]
 ....
 redirect_port tcp 192.168.0.2:6667 6667
 redirect_port tcp 192.168.0.3:80 80
 ....
 
 After adding these arguments to the configuration of NAT instance 1 in the above ruleset, the TCP ports will be port forwarded to the LAN client machines running the IRC and HTTP services.
 
 [.programlisting]
 ....
 ipfw -q nat 1 config if $pif same_ports unreg_only reset \
   redirect_port tcp 192.168.0.2:6667 6667 \
   redirect_port tcp 192.168.0.3:80 80
 ....
 
 Port ranges over individual ports can be indicated with `redirect_port`.
 For example, _tcp 192.168.0.2:2000-3000 2000-3000_ would redirect all connections received on ports 2000 to 3000 to ports 2000 to 3000 on client `A`.
 
 ==== Address Redirection
 
 Address redirection is useful if more than one IP address is available.
 Each LAN client can be assigned its own external IP address by man:ipfw[8], which will then rewrite outgoing packets from the LAN clients with the proper external IP address and redirects all traffic incoming on that particular IP address back to the specific LAN client.
 This is also known as static NAT.
 For example, if IP addresses `128.1.1.1`, `128.1.1.2`, and `128.1.1.3` are available, `128.1.1.1` can be used as the man:ipfw[8] machine's external IP address, while `128.1.1.2` and `128.1.1.3` are forwarded back to LAN clients `A` and `B`.
 
 The `redirect_address` syntax is as below, where `localIP` is the internal IP address of the LAN client, and `publicIP` the external IP address corresponding to the LAN client.
 
 [.programlisting]
 ....
 redirect_address localIP publicIP
 ....
 
 In the example, the arguments would read:
 
 [.programlisting]
 ....
 redirect_address 192.168.0.2 128.1.1.2
 redirect_address 192.168.0.3 128.1.1.3
 ....
 
 Like `redirect_port`, these arguments are placed in a NAT instance configuration.
 With address redirection, there is no need for port redirection, as all data received on a particular IP address is redirected.
 
 The external IP addresses on the man:ipfw[8] machine must be active and aliased to the external interface.
 Refer to man:rc.conf[5] for details.
 
 ==== Userspace NAT
 
 Let us start with a statement: the userspace NAT implementation: man:natd[8], has more overhead than in-kernel NAT.
 For man:natd[8] to translate packets, the packets have to be copied from the kernel to userspace and back which brings in extra overhead that is not present with in-kernel NAT.
 
 To enable the userpace NAT daemon man:natd[8] at boot time, the following is a minimum configuration in [.filename]#/etc/rc.conf#.
 Where `natd_interface` is set to the name of the NIC attached to the Internet.
 The man:rc[8] script of man:natd[8] will automatically check if a dynamic IP address is used and configure itself to handle that.
 
 [.programlisting]
 ....
 gateway_enable="YES"
 natd_enable="YES"
 natd_interface="rl0"
 ....
 
 In general, the above ruleset as explained for in-kernel NAT can also be used together with man:natd[8].
 The exceptions are the configuration of the in-kernel NAT instance `(ipfw -q nat 1 config ...)` which is not needed together with reassemble rule 99 because its functionality is included in the `divert` action.
 Rule number 100 and 1000 will have to change sligthly as shown below.
 
 [.programlisting]
 ....
 $cmd 100 divert natd ip from any to any in via $pif
 $cmd 1000 divert natd ip from any to any out via $pif
 ....
 
 To configure port or address redirection, a similar syntax as with in-kernel NAT is used.
 Although, now, instead of specifying the configuration in our ruleset script like with in-kernel NAT, configuration of man:natd[8] is best done in a configuration file.
 To do this, an extra flag must be passed via [.filename]#/etc/rc.conf# which specifies the path of the configuration file.
 
 [.programlisting]
 ....
 natd_flags="-f /etc/natd.conf"
 ....
 
 [NOTE]
 ====
 The specified file must contain a list of configuration options, one per line.
 For more information about the configuration file and possible variables, consult man:natd[8].
 Below are two example entries, one per line:
 
 [.programlisting]
 ....
 redirect_port tcp 192.168.0.2:6667 6667
 redirect_address 192.168.0.3 128.1.1.3
 ....
 
 ====
 
 [[firewalls-ipfw-cmd]]
 === The IPFW Command
 
 `ipfw` can be used to make manual, single rule additions or deletions to the active firewall while it is running.
 The problem with using this method is that all the changes are lost when the system reboots.
 It is recommended to instead write all the rules in a file and to use that file to load the rules at boot time and to replace the currently running firewall rules whenever that file changes.
 
 `ipfw` is a useful way to display the running firewall rules to the console screen.
 The IPFW accounting facility dynamically creates a counter for each rule that counts each packet that matches the rule.
 During the process of testing a rule, listing the rule with its counter is one way to determine if the rule is functioning as expected.
 
 To list all the running rules in sequence:
 
 [source,shell]
 ....
 # ipfw list
 ....
 
 To list all the running rules with a time stamp of when the last time the rule was matched:
 
 [source,shell]
 ....
 # ipfw -t list
 ....
 
 The next example lists accounting information and the packet count for matched rules along with the rules themselves.
 The first column is the rule number, followed by the number of matched packets and bytes, followed by the rule itself.
 
 [source,shell]
 ....
 # ipfw -a list
 ....
 
 To list dynamic rules in addition to static rules:
 
 [source,shell]
 ....
 # ipfw -d list
 ....
 
 To also show the expired dynamic rules:
 
 [source,shell]
 ....
 # ipfw -d -e list
 ....
 
 To zero the counters:
 
 [source,shell]
 ....
 # ipfw zero
 ....
 
 To zero the counters for just the rule with number _NUM_:
 
 [source,shell]
 ....
 # ipfw zero NUM
 ....
 
 ==== Logging Firewall Messages
 
 Even with the logging facility enabled, IPFW will not generate any rule logging on its own.
 The firewall administrator decides which rules in the ruleset will be logged, and adds the `log` keyword to those rules.
 Normally only deny rules are logged.
 It is customary to duplicate the "ipfw default deny everything" rule with the `log` keyword included as the last rule in the ruleset.
 This way, it is possible to see all the packets that did not match any of the rules in the ruleset.
 
 Logging is a two edged sword.
 If one is not careful, an over abundance of log data or a DoS attack can fill the disk with log files.
 Log messages are not only written to syslogd, but also are displayed on the root console screen and soon become annoying.
 
 The `IPFIREWALL_VERBOSE_LIMIT=5` kernel option limits the number of consecutive messages sent to man:syslogd[8], concerning the packet matching of a given rule.
 When this option is enabled in the kernel, the number of consecutive messages concerning a particular rule is capped at the number specified.
 There is nothing to be gained from 200 identical log messages.
 With this option set to five, five consecutive messages concerning a particular rule would be logged to syslogd and the remainder identical consecutive messages would be counted and posted to syslogd with a phrase like the following:
 
 [.programlisting]
 ....
 last message repeated 45 times
 ....
 
 All logged packets messages are written by default to [.filename]#/var/log/security#, which is defined in [.filename]#/etc/syslog.conf#.
 
 [[firewalls-ipfw-rules-script]]
 ==== Building a Rule Script
 
 Most experienced IPFW users create a file containing the rules and code them in a manner compatible with running them as a script.
 The major benefit of doing this is the firewall rules can be refreshed in mass without the need of rebooting the system to activate them.
 This method is convenient in testing new rules as the procedure can be executed as many times as needed.
 Being a script, symbolic substitution can be used for frequently used values to be substituted into multiple rules.
 
 This example script is compatible with the syntax used by the man:sh[1], man:csh[1], and man:tcsh[1] shells.
 Symbolic substitution fields are prefixed with a dollar sign ($).
 Symbolic fields do not have the $ prefix.
 The value to populate the symbolic field must be enclosed in double quotes ("").
 
 Start the rules file like this:
 
 [.programlisting]
 ....
 ############### start of example ipfw rules script #############
 #
 ipfw -q -f flush       # Delete all rules
 # Set defaults
 oif="tun0"             # out interface
 odns="192.0.2.11"      # ISP's DNS server IP address
 cmd="ipfw -q add "     # build rule prefix
 ks="keep-state"        # just too lazy to key this each time
 $cmd 00500 check-state
 $cmd 00502 deny all from any to any frag
 $cmd 00501 deny tcp from any to any established
 $cmd 00600 allow tcp from any to any 80 out via $oif setup $ks
 $cmd 00610 allow tcp from any to $odns 53 out via $oif setup $ks
 $cmd 00611 allow udp from any to $odns 53 out via $oif $ks
 ################### End of example ipfw rules script ############
 ....
 
 The rules are not important as the focus of this example is how the symbolic substitution fields are populated.
 
 If the above example was in [.filename]#/etc/ipfw.rules#, the rules could be reloaded by the following command:
 
 [source,shell]
 ....
 # sh /etc/ipfw.rules
 ....
 
 [.filename]#/etc/ipfw.rules# can be located anywhere and the file can have any name.
 
 The same thing could be accomplished by running these commands by hand:
 
 [source,shell]
 ....
 # ipfw -q -f flush
 # ipfw -q add check-state
 # ipfw -q add deny all from any to any frag
 # ipfw -q add deny tcp from any to any established
 # ipfw -q add allow tcp from any to any 80 out via tun0 setup keep-state
 # ipfw -q add allow tcp from any to 192.0.2.11 53 out via tun0 setup keep-state
 # ipfw -q add 00611 allow udp from any to 192.0.2.11 53 out via tun0 keep-state
 ....
 
 [[firewalls-ipfw-kernelconfig]]
 === IPFW Kernel Options
 
 In order to statically compile IPFW support into a custom kernel, refer to the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel].
 The following options are available for the custom kernel configuration file:
 
 [.programlisting]
 ....
 options    IPFIREWALL			# enables IPFW
 options    IPFIREWALL_VERBOSE		# enables logging for rules with log keyword to syslogd(8)
 options    IPFIREWALL_VERBOSE_LIMIT=5	# limits number of logged packets per-entry
 options    IPFIREWALL_DEFAULT_TO_ACCEPT # sets default policy to pass what is not explicitly denied
 options    IPFIREWALL_NAT		# enables basic in-kernel NAT support
 options    LIBALIAS			# enables full in-kernel NAT support
 options    IPFIREWALL_NAT64		# enables in-kernel NAT64 support
 options    IPFIREWALL_NPTV6		# enables in-kernel IPv6 NPT support
 options    IPFIREWALL_PMOD		# enables protocols modification module support
 options    IPDIVERT			# enables NAT through natd(8)
 ....
 
 [NOTE]
 ====
 IPFW can be loaded as a kernel module: options above are built by default as modules or can be set at runtime using tunables.
 ====
 
 [[firewalls-ipf]]
 == IPFILTER (IPF)
 
 IPFILTER, also known as IPF, is a cross-platform, open source firewall which has been ported to several operating systems, including FreeBSD, NetBSD, OpenBSD, and Solaris(TM).
 
 IPFILTER is a kernel-side firewall and NAT mechanism that can be controlled and monitored by userland programs.
 Firewall rules can be set or deleted using ipf, NAT rules can be set or deleted using ipnat, run-time statistics for the kernel parts of IPFILTER can be printed using ipfstat, and ipmon can be used to log IPFILTER actions to the system log files.
 
 IPF was originally written using a rule processing logic of "the last matching rule wins" and only used stateless rules.
 Since then, IPF has been enhanced to include the `quick` and `keep state` options.
 
 The IPF FAQ is at http://www.phildev.net/ipf/index.html[http://www.phildev.net/ipf/index.html].
 A searchable archive of the IPFilter mailing list is available at http://marc.info/?l=ipfilter[http://marc.info/?l=ipfilter].
 
 This section of the Handbook focuses on IPF as it pertains to FreeBSD.
 It provides examples of rules that contain the `quick` and `keep state` options.
 
 === Enabling IPF
 
 IPF is included in the basic FreeBSD install as a kernel loadable module, meaning that a custom kernel is not needed in order to enable IPF.
 
 For users who prefer to statically compile IPF support into a custom kernel, refer to the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel].
 The following kernel options are available:
 
 [.programlisting]
 ....
 options IPFILTER
 options IPFILTER_LOG
 options IPFILTER_LOOKUP
 options IPFILTER_DEFAULT_BLOCK
 ....
 
 where `options IPFILTER` enables support for IPFILTER, `options IPFILTER_LOG` enables IPF logging using the [.filename]#ipl# packet logging pseudo-device for every rule that has the `log` keyword, `IPFILTER_LOOKUP` enables IP pools in order to speed up IP lookups, and `options IPFILTER_DEFAULT_BLOCK` changes the default behavior so that any packet not matching a firewall `pass` rule gets blocked.
 
 To configure the system to enable IPF at boot time, add the following entries to [.filename]#/etc/rc.conf#.
 These entries will also enable logging and `default pass all`.
 To change the default policy to `block all` without compiling a custom kernel, remember to add a `block all` rule at the end of the ruleset.
 
 [.programlisting]
 ....
 ipfilter_enable="YES"             # Start ipf firewall
 ipfilter_rules="/etc/ipf.rules"   # loads rules definition text file
 ipv6_ipfilter_rules="/etc/ipf6.rules" # loads rules definition text file for IPv6
 ipmon_enable="YES"                # Start IP monitor log
 ipmon_flags="-Ds"                 # D = start as daemon
                                   # s = log to syslog
                                   # v = log tcp window, ack, seq
                                   # n = map IP & port to names
 ....
 
 If NAT functionality is needed, also add these lines:
 
 [.programlisting]
 ....
 gateway_enable="YES"              # Enable as LAN gateway
 ipnat_enable="YES"                # Start ipnat function
 ipnat_rules="/etc/ipnat.rules"    # rules definition file for ipnat
 ....
 
 Then, to start IPF now:
 
 [.programlisting]
 ....
 #  service ipfilter start
 ....
 
 To load the firewall rules, specify the name of the ruleset file using `ipf`.
 The following command can be used to replace the currently running firewall rules:
 
 [source,shell]
 ....
 # ipf -Fa -f /etc/ipf.rules
 ....
 
 where `-Fa` flushes all the internal rules tables and `-f` specifies the file containing the rules to load.
 
 This provides the ability to make changes to a custom ruleset and update the running firewall with a fresh copy of the rules without having to reboot the system.
 This method is convenient for testing new rules as the procedure can be executed as many times as needed.
 
 Refer to man:ipf[8] for details on the other flags available with this command.
 
 === IPF Rule Syntax
 
 This section describes the IPF rule syntax used to create stateful rules.
 When creating rules, keep in mind that unless the `quick` keyword appears in a rule, every rule is read in order, with the _last matching rule_ being the one that is applied.
 This means that even if the first rule to match a packet is a `pass`, if there is a later matching rule that is a `block`, the packet will be dropped.
 Sample rulesets can be found in [.filename]#/usr/share/examples/ipfilter#.
 
 When creating rules, a `#` character is used to mark the start of a comment and may appear at the end of a rule, to explain that rule's function, or on its own line.
 Any blank lines are ignored.
 
 The keywords which are used in rules must be written in a specific order, from left to right.
 Some keywords are mandatory while others are optional.
 Some keywords have sub-options which may be keywords themselves and also include more sub-options.
 The keyword order is as follows, where the words shown in uppercase represent a variable and the words shown in lowercase must precede the variable that follows it:
 
 `_ACTION DIRECTION OPTIONS proto PROTO_TYPE from SRC_ADDR SRC_PORT to DST_ADDR DST_PORT TCP_FLAG|ICMP_TYPE keep state STATE_`
 
 This section describes each of these keywords and their options.
 It is not an exhaustive list of every possible option.
 Refer to man:ipf[5] for a complete description of the rule syntax that can be used when creating IPF rules and examples for using each keyword.
 
 ACTION::
 The action keyword indicates what to do with the packet if it matches that rule.
 Every rule _must_ have an action.
 The following actions are recognized:
 +
 `block`: drops the packet.
 +
 `pass`: allows the packet.
 +
 `log`: generates a log record.
 +
 `count`: counts the number of packets and bytes which can provide an indication of how often a rule is used.
 +
 `auth`: queues the packet for further processing by another program.
 +
 `call`: provides access to functions built into IPF that allow more complex actions.
 +
 `decapsulate`: removes any headers in order to process the contents of the packet.
 
 DIRECTION::
 Next, each rule must explicitly state the direction of traffic using one of these keywords:
 +
 `in`: the rule is applied against an inbound packet.
 +
 `out`: the rule is applied against an outbound packet.
 +
 `all`: the rule applies to either direction.
 +
 If the system has multiple interfaces, the interface can be specified along with the direction. An example would be `in on fxp0`.
 
 OPTIONS::
 Options are optional.
 However, if multiple options are specified, they must be used in the order shown here.
 +
 `log`: when performing the specified ACTION, the contents of the packet's headers will be written to the man:ipl[4] packet log pseudo-device.
 +
 `quick`: if a packet matches this rule, the ACTION specified by the rule occurs and no further processing of any following rules will occur for this packet.
 +
 `on`: must be followed by the interface name as displayed by man:ifconfig[8].
 The rule will only match if the packet is going through the specified interface in the specified direction.
 +
 When using the `log` keyword, the following qualifiers may be used in this order:
 +
 `body`: indicates that the first 128 bytes of the packet contents will be logged after the headers.
 +
 `first`: if the `log` keyword is being used in conjunction with a `keep state` option, this option is recommended so that only the triggering packet is logged and not every packet which matches the stateful connection.
 +
 Additional options are available to specify error return messages.
 Refer to man:ipf[5] for more details.
 
 PROTO_TYPE::
 The protocol type is optional.
 However, it is mandatory if the rule needs to specify a SRC_PORT or a DST_PORT as it defines the type of protocol.
 When specifying the type of protocol, use the `proto` keyword followed by either a protocol number or name from [.filename]#/etc/protocols#.
 Example protocol names include `tcp`, `udp`, or `icmp`.
 If PROTO_TYPE is specified but no SRC_PORT or DST_PORT is specified, all port numbers for that protocol will match that rule.
 
 SRC_ADDR::
 The `from` keyword is mandatory and is followed by a keyword which represents the source of the packet.
 The source can be a hostname, an IP address followed by the CIDR mask, an address pool, or the keyword `all`.
 Refer to man:ipf[5] for examples.
 +
 There is no way to match ranges of IP addresses which do not express themselves easily using the dotted numeric form / mask-length notation.
 The package:net-mgmt/ipcalc[] package or port may be used to ease the calculation of the CIDR mask.
 Additional information is available at the utility's web page: http://jodies.de/ipcalc[http://jodies.de/ipcalc].
 
 SRC_PORT::
 The port number of the source is optional.
 However, if it is used, it requires PROTO_TYPE to be first defined in the rule.
 The port number must also be preceded by the `proto` keyword.
 +
 A number of different comparison operators are supported: `=` (equal to), `!=` (not equal to), `<` (less than), `>` (greater than), `<=` (less than or equal to), and `>=` (greater than or equal to).
 +
 To specify port ranges, place the two port numbers between `<>` (less than and greater than ), `><` (greater than and less than ), or `:` (greater than or equal to and less than or equal to).
 
 DST_ADDR::
 The `to` keyword is mandatory and is followed by a keyword which represents the destination of the packet.
 Similar to SRC_ADDR, it can be a hostname, an IP address followed by the CIDR mask, an address pool, or the keyword `all`.
 
 DST_PORT::
 Similar to SRC_PORT, the port number of the destination is optional.
 However, if it is used, it requires PROTO_TYPE to be first defined in the rule.
 The port number must also be preceded by the `proto` keyword.
 
 TCP_FLAG|ICMP_TYPE::
 If `tcp` is specified as the PROTO_TYPE, flags can be specified as letters, where each letter represents one of the possible TCP flags used to determine the state of a connection.
 Possible values are: `S` (SYN), `A` (ACK), `P` (PSH), `F` (FIN), `U` (URG), `R` (RST), `C` (CWN), and `E` (ECN).
 +
 If `icmp` is specified as the PROTO_TYPE, the ICMP type to match can be specified.
 Refer to man:ipf[5] for the allowable types.
 
 STATE::
 If a `pass` rule contains `keep state`, IPF will add an entry to its dynamic state table and allow subsequent packets that match the connection.
 IPF can track state for TCP, UDP, and ICMP sessions.
 Any packet that IPF can be certain is part of an active session, even if it is a different protocol, will be allowed.
 +
 In IPF, packets destined to go out through the interface connected to the public Internet are first checked against the dynamic state table.
 If the packet matches the next expected packet comprising an active session conversation, it exits the firewall and the state of the session conversation flow is updated in the dynamic state table.
 Packets that do not belong to an already active session are checked against the outbound ruleset.
 Packets coming in from the interface connected to the public Internet are first checked against the dynamic state table.
 If the packet matches the next expected packet comprising an active session, it exits the firewall and the state of the session conversation flow is updated in the dynamic state table.
 Packets that do not belong to an already active session are checked against the inbound ruleset.
 +
 Several keywords can be added after `keep state`.
 If used, these keywords set various options that control stateful filtering, such as setting connection limits or connection age.
 Refer to man:ipf[5] for the list of available options and their descriptions.
 
 === Example Ruleset
 
 This section demonstrates how to create an example ruleset which only allows services matching `pass` rules and blocks all others.
 
 FreeBSD uses the loopback interface ([.filename]#lo0#) and the IP address `127.0.0.1` for internal communication.
 The firewall ruleset must contain rules to allow free movement of these internally used packets:
 
 [.programlisting]
 ....
 # no restrictions on loopback interface
 pass in quick on lo0 all
 pass out quick on lo0 all
 ....
 
 The public interface connected to the Internet is used to authorize and control access of all outbound and inbound connections.
 If one or more interfaces are cabled to private networks, those internal interfaces may require rules to allow packets originating from the LAN to flow between the internal networks or to the interface attached to the Internet.
 The ruleset should be organized into three major sections: any trusted internal interfaces, outbound connections through the public interface, and inbound connections through the public interface.
 
 These two rules allow all traffic to pass through a trusted LAN interface named [.filename]#xl0#:
 
 [.programlisting]
 ....
 # no restrictions on inside LAN interface for private network
 pass out quick on xl0 all
 pass in quick on xl0 all
 ....
 
 The rules for the public interface's outbound and inbound sections should have the most frequently matched rules placed before less commonly matched rules, with the last rule in the section blocking and logging all packets for that interface and direction.
 
 This set of rules defines the outbound section of the public interface named [.filename]#dc0#.
 These rules keep state and identify the specific services that internal systems are authorized for public Internet access.
 All the rules use `quick` and specify the appropriate port numbers and, where applicable, destination addresses.
 
 [.programlisting]
 ....
 # interface facing Internet (outbound)
 # Matches session start requests originating from or behind the
 # firewall, destined for the Internet.
 
 # Allow outbound access to public DNS servers.
 # Replace x.x.x. with address listed in /etc/resolv.conf.
 # Repeat for each DNS server.
 pass out quick on dc0 proto tcp from any to x.x.x. port = 53 flags S keep state
 pass out quick on dc0 proto udp from any to xxx port = 53 keep state
 
 # Allow access to ISP's specified DHCP server for cable or DSL networks.
 # Use the first rule, then check log for the IP address of DHCP server.
 # Then, uncomment the second rule, replace z.z.z.z with the IP address,
 # and comment out the first rule
 pass out log quick on dc0 proto udp from any to any port = 67 keep state
 #pass out quick on dc0 proto udp from any to z.z.z.z port = 67 keep state
 
 # Allow HTTP and HTTPS
 pass out quick on dc0 proto tcp from any to any port = 80 flags S keep state
 pass out quick on dc0 proto tcp from any to any port = 443 flags S keep state
 
 # Allow email
 pass out quick on dc0 proto tcp from any to any port = 110 flags S keep state
 pass out quick on dc0 proto tcp from any to any port = 25 flags S keep state
 
 # Allow NTP
 pass out quick on dc0 proto tcp from any to any port = 37 flags S keep state
 
 # Allow FTP
 pass out quick on dc0 proto tcp from any to any port = 21 flags S keep state
 
 # Allow SSH
 pass out quick on dc0 proto tcp from any to any port = 22 flags S keep state
 
 # Allow ping
 pass out quick on dc0 proto icmp from any to any icmp-type 8 keep state
 
 # Block and log everything else
 block out log first quick on dc0 all
 ....
 
 This example of the rules in the inbound section of the public interface blocks all undesirable packets first.
 This reduces the number of packets that are logged by the last rule.
 
 [.programlisting]
 ....
 # interface facing Internet (inbound)
 # Block all inbound traffic from non-routable or reserved address spaces
 block in quick on dc0 from 192.168.0.0/16 to any    #RFC 1918 private IP
 block in quick on dc0 from 172.16.0.0/12 to any     #RFC 1918 private IP
 block in quick on dc0 from 10.0.0.0/8 to any        #RFC 1918 private IP
 block in quick on dc0 from 127.0.0.0/8 to any       #loopback
 block in quick on dc0 from 0.0.0.0/8 to any         #loopback
 block in quick on dc0 from 169.254.0.0/16 to any    #DHCP auto-config
 block in quick on dc0 from 192.0.2.0/24 to any      #reserved for docs
 block in quick on dc0 from 204.152.64.0/23 to any   #Sun cluster interconnect
 block in quick on dc0 from 224.0.0.0/3 to any       #Class D & E multicast
 
 # Block fragments and too short tcp packets
 block in quick on dc0 all with frags
 block in quick on dc0 proto tcp all with short
 
 # block source routed packets
 block in quick on dc0 all with opt lsrr
 block in quick on dc0 all with opt ssrr
 
 # Block OS fingerprint attempts and log first occurrence
 block in log first quick on dc0 proto tcp from any to any flags FUP
 
 # Block anything with special options
 block in quick on dc0 all with ipopts
 
 # Block public pings and ident
 block in quick on dc0 proto icmp all icmp-type 8
 block in quick on dc0 proto tcp from any to any port = 113
 
 # Block incoming Netbios services
 block in log first quick on dc0 proto tcp/udp from any to any port = 137
 block in log first quick on dc0 proto tcp/udp from any to any port = 138
 block in log first quick on dc0 proto tcp/udp from any to any port = 139
 block in log first quick on dc0 proto tcp/udp from any to any port = 81
 ....
 
 Any time there are logged messages on a rule with the `log first` option, run `ipfstat -hio` to evaluate how many times the rule has been matched.
 A large number of matches may indicate that the system is under attack.
 
 The rest of the rules in the inbound section define which connections are allowed to be initiated from the Internet.
 The last rule denies all connections which were not explicitly allowed by previous rules in this section.
 
 [.programlisting]
 ....
 # Allow traffic in from ISP's DHCP server. Replace z.z.z.z with
 # the same IP address used in the outbound section.
 pass in quick on dc0 proto udp from z.z.z.z to any port = 68 keep state
 
 # Allow public connections to specified internal web server
 pass in quick on dc0 proto tcp from any to x.x.x.x port = 80 flags S keep state
 
 # Block and log only first occurrence of all remaining traffic.
 block in log first quick on dc0 all
 ....
 
 === Configuring NAT
 
 To enable NAT, add these statements to [.filename]#/etc/rc.conf# and specify the name of the file containing the NAT rules:
 
 [.programlisting]
 ....
 gateway_enable="YES"
 ipnat_enable="YES"
 ipnat_rules="/etc/ipnat.rules"
 ....
 
 NAT rules are flexible and can accomplish many different things to fit the needs of both commercial and home users.
 The rule syntax presented here has been simplified to demonstrate common usage.
 For a complete rule syntax description, refer to man:ipnat[5].
 
 The basic syntax for a NAT rule is as follows, where `map` starts the rule and _IF_ should be replaced with the name of the external interface:
 
 [.programlisting]
 ....
 map IF LAN_IP_RANGE -> PUBLIC_ADDRESS
 ....
 
 The _LAN_IP_RANGE_ is the range of IP addresses used by internal clients.
 Usually, it is a private address range such as `192.168.1.0/24`.
 The _PUBLIC_ADDRESS_ can either be the static external IP address or the keyword `0/32` which represents the IP address assigned to _IF_.
 
 In IPF, when a packet arrives at the firewall from the LAN with a public destination, it first passes through the outbound rules of the firewall ruleset.
 Then, the packet is passed to the NAT ruleset which is read from the top down, where the first matching rule wins.
 IPF tests each NAT rule against the packet's interface name and source IP address.
 When a packet's interface name matches a NAT rule, the packet's source IP address in the private LAN is checked to see if it falls within the IP address range specified in _LAN_IP_RANGE_.
 On a match, the packet has its source IP address rewritten with the public IP address specified by _PUBLIC_ADDRESS_.
 IPF posts an entry in its internal NAT table so that when the packet returns from the Internet, it can be mapped back to its original private IP address before being passed to the firewall rules for further processing.
 
 For networks that have large numbers of internal systems or multiple subnets, the process of funneling every private IP address into a single public IP address becomes a resource problem.
 Two methods are available to relieve this issue.
 
 The first method is to assign a range of ports to use as source ports.
 By adding the `portmap` keyword, NAT can be directed to only use source ports in the specified range:
 
 [.programlisting]
 ....
 map dc0 192.168.1.0/24 -> 0/32 portmap tcp/udp 20000:60000
 ....
 
 Alternately, use the `auto` keyword which tells NAT to determine the ports that are available for use:
 
 [.programlisting]
 ....
 map dc0 192.168.1.0/24 -> 0/32 portmap tcp/udp auto
 ....
 
 The second method is to use a pool of public addresses.
 This is useful when there are too many LAN addresses to fit into a single public address and a block of public IP addresses is available.
 These public addresses can be used as a pool from which NAT selects an IP address as a packet's address is mapped on its way out.
 
 The range of public IP addresses can be specified using a netmask or CIDR notation.
 These two rules are equivalent:
 
 [.programlisting]
 ....
 map dc0 192.168.1.0/24 -> 204.134.75.0/255.255.255.0
 map dc0 192.168.1.0/24 -> 204.134.75.0/24
 ....
 
 A common practice is to have a publically accessible web server or mail server segregated to an internal network segment.
 The traffic from these servers still has to undergo NAT, but port redirection is needed to direct inbound traffic to the correct server.
 For example, to map a web server using the internal address `10.0.10.25` to its public IP address of `20.20.20.5`, use this rule:
 
 [.programlisting]
 ....
 rdr dc0 20.20.20.5/32 port 80 -> 10.0.10.25 port 80
 ....
 
 If it is the only web server, this rule would also work as it redirects all external HTTP requests to `10.0.10.25`:
 
 [.programlisting]
 ....
 rdr dc0 0.0.0.0/0 port 80 -> 10.0.10.25 port 80
 ....
 
 IPF has a built in FTP proxy which can be used with NAT.
 It monitors all outbound traffic for active or passive FTP connection requests and dynamically creates temporary filter rules containing the port number used by the FTP data channel.
 This eliminates the need to open large ranges of high order ports for FTP connections.
 
 In this example, the first rule calls the proxy for outbound FTP traffic from the internal LAN.
 The second rule passes the FTP traffic from the firewall to the Internet, and the third rule handles all non-FTP traffic from the internal LAN:
 
 [.programlisting]
 ....
 map dc0 10.0.10.0/29 -> 0/32 proxy port 21 ftp/tcp
 map dc0 0.0.0.0/0 -> 0/32 proxy port 21 ftp/tcp
 map dc0 10.0.10.0/29 -> 0/32
 ....
 
 The FTP `map` rules go before the NAT rule so that when a packet matches an FTP rule, the FTP proxy creates temporary filter rules to let the FTP session packets pass and undergo NAT.
 All LAN packets that are not FTP will not match the FTP rules but will undergo NAT if they match the third rule.
 
 Without the FTP proxy, the following firewall rules would instead be needed.
 Note that without the proxy, all ports above `1024` need to be allowed:
 
 [.programlisting]
 ....
 # Allow out LAN PC client FTP to public Internet
 # Active and passive modes
 pass out quick on rl0 proto tcp from any to any port = 21 flags S keep state
 
 # Allow out passive mode data channel high order port numbers
 pass out quick on rl0 proto tcp from any to any port > 1024 flags S keep state
 
 # Active mode let data channel in from FTP server
 pass in quick on rl0 proto tcp from any to any port = 20 flags S keep state
 ....
 
 Whenever the file containing the NAT rules is edited, run `ipnat` with `-CF` to delete the current NAT rules and flush the contents of the dynamic translation table.
 Include `-f` and specify the name of the NAT ruleset to load:
 
 [source,shell]
 ....
 # ipnat -CF -f /etc/ipnat.rules
 ....
 
 To display the NAT statistics:
 
 [source,shell]
 ....
 # ipnat -s
 ....
 
 To list the NAT table's current mappings:
 
 [source,shell]
 ....
 # ipnat -l
 ....
 
 To turn verbose mode on and display information relating to rule processing and active rules and table entries:
 
 [source,shell]
 ....
 # ipnat -v
 ....
 
 === Viewing IPF Statistics
 
 IPF includes man:ipfstat[8] which can be used to retrieve and display statistics which are gathered as packets match rules as they go through the firewall. 
 Statistics are accumulated since the firewall was last started or since the last time they were reset to zero using `ipf -Z`.
 
 The default `ipfstat` output looks like this:
 
 [source,shell]
 ....
 input packets: blocked 99286 passed 1255609 nomatch 14686 counted 0
  output packets: blocked 4200 passed 1284345 nomatch 14687 counted 0
  input packets logged: blocked 99286 passed 0
  output packets logged: blocked 0 passed 0
  packets logged: input 0 output 0
  log failures: input 3898 output 0
  fragment state(in): kept 0 lost 0
  fragment state(out): kept 0 lost 0
  packet state(in): kept 169364 lost 0
  packet state(out): kept 431395 lost 0
  ICMP replies: 0 TCP RSTs sent: 0
  Result cache hits(in): 1215208 (out): 1098963
  IN Pullups succeeded: 2 failed: 0
  OUT Pullups succeeded: 0 failed: 0
  Fastroute successes: 0 failures: 0
  TCP cksum fails(in): 0 (out): 0
  Packet log flags set: (0)
 ....
 
 Several options are available.
 When supplied with either `-i` for inbound or `-o` for outbound, the command will retrieve and display the appropriate list of filter rules currently installed and in use by the kernel.
 To also see the rule numbers, include `-n`.
 For example, `ipfstat -on` displays the outbound rules table with rule numbers:
 
 [source,shell]
 ....
 @1 pass out on xl0 from any to any
 @2 block out on dc0 from any to any
 @3 pass out quick on dc0 proto tcp/udp from any to any keep state
 ....
 
 Include `-h` to prefix each rule with a count of how many times the rule was matched.
 For example, `ipfstat -oh` displays the outbound internal rules table, prefixing each rule with its usage count:
 
 [source,shell]
 ....
 2451423 pass out on xl0 from any to any
 354727 block out on dc0 from any to any
 430918 pass out quick on dc0 proto tcp/udp from any to any keep state
 ....
 
 To display the state table in a format similar to man:top[1], use `ipfstat -t`.
 When the firewall is under attack, this option provides the ability to identify and see the attacking packets.
 The optional sub-flags give the ability to select the destination or source IP, port, or protocol to be monitored in real time.
 Refer to man:ipfstat[8] for details.
 
 === IPF Logging
 
 IPF provides `ipmon`, which can be used to write the firewall's logging information in a human readable format.
 It requires that `options IPFILTER_LOG` be first added to a custom kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel].
 
 This command is typically run in daemon mode in order to provide a continuous system log file so that logging of past events may be reviewed.
 Since FreeBSD has a built in man:syslogd[8] facility to automatically rotate system logs, the default [.filename]#rc.conf# `ipmon_flags` statement uses `-Ds`:
 
 [.programlisting]
 ....
 ipmon_flags="-Ds" # D = start as daemon
                   # s = log to syslog
                   # v = log tcp window, ack, seq
                   # n = map IP & port to names
 ....
 
 Logging provides the ability to review, after the fact, information such as which packets were dropped, what addresses they came from, and where they were going.
 This information is useful in tracking down attackers.
 
 Once the logging facility is enabled in [.filename]#rc.conf# and started with `service ipmon start`, IPF will only log the rules which contain the `log` keyword.
 The firewall administrator decides which rules in the ruleset should be logged and normally only deny rules are logged.
 It is customary to include the `log` keyword in the last rule in the ruleset.
 This makes it possible to see all the packets that did not match any of the rules in the ruleset.
 
 By default, `ipmon -Ds` mode uses `local0` as the logging facility.
 The following logging levels can be used to further segregate the logged data:
 
 [source,shell]
 ....
 LOG_INFO - packets logged using the "log" keyword as the action rather than pass or block.
 LOG_NOTICE - packets logged which are also passed
 LOG_WARNING - packets logged which are also blocked
 LOG_ERR - packets which have been logged and which can be considered short due to an incomplete header
 ....
 
 In order to setup IPF to log all data to [.filename]#/var/log/ipfilter.log#, first create the empty file:
 
 [source,shell]
 ....
 # touch /var/log/ipfilter.log
 ....
 
 Then, to write all logged messages to the specified file, add the following statement to [.filename]#/etc/syslog.conf#:
 
 [.programlisting]
 ....
 local0.* /var/log/ipfilter.log
 ....
 
 To activate the changes and instruct man:syslogd[8] to read the modified [.filename]#/etc/syslog.conf#, run `service syslogd reload`.
 
 Do not forget to edit [.filename]#/etc/newsyslog.conf# to rotate the new log file.
 
 Messages generated by `ipmon` consist of data fields separated by white space.
 Fields common to all messages are:
 
 . The date of packet receipt.
 . The time of packet receipt. This is in the form HH:MM:SS.F, for hours, minutes, seconds, and fractions of a second.
 . The name of the interface that processed the packet.
 . The group and rule number of the rule in the format `@0:17`.
 . The action: `p` for passed, `b` for blocked, `S` for a short packet, `n` did not match any rules, and `L` for a log rule.
 . The addresses written as three fields: the source address and port separated by a comma, the -> symbol, and the destination address and port. For example: `209.53.17.22,80 -> 198.73.220.17,1722`.
 . `PR` followed by the protocol name or number: for example, `PR tcp`.
 . `len` followed by the header length and total length of the packet: for example, `len 20 40`.
 
 If the packet is a TCP packet, there will be an additional field starting with a hyphen followed by letters corresponding to any flags that were set.
 Refer to man:ipf[5] for a list of letters and their flags.
 
 If the packet is an ICMP packet, there will be two fields at the end: the first always being "icmp" and the next being the ICMP message and sub-message type, separated by a slash.
 For example: `icmp 3/3` for a port unreachable message.
 
 [[firewalls-blacklistd]]
 == Blacklistd
 
 Blacklistd is a daemon listening to sockets to receive notifications from other daemons about connection attempts that failed or were successful.
 It is most widely used in blocking too many connection attempts on open ports.
 A prime example is SSH running on the internet getting a lot of requests from bots or scripts trying to guess passwords and gain access.
 Using blacklistd, the daemon can notify the firewall to create a filter rule to block excessive connection attempts from a single source after a number of tries. Blacklistd was first developed on NetBSD and appeared there in version 7.
 FreeBSD 11 imported blacklistd from NetBSD.
 
 This chapter describes how to set up blacklistd, configure it, and provides examples on how to use it.
 Readers should be familiar with basic firewall concepts like rules.
 For details, refer to the firewall chapter.
 PF is used in the examples, but other firewalls available on FreeBSD should be able to work with blacklistd, too.
 
 === Enabling Blacklistd
 
 The main configuration for blacklistd is stored in man:blacklistd.conf[5].
 Various command line options are also available to change blacklistd's run-time behavior.
 Persistent configuration across reboots should be stored in [.filename]#/etc/blacklistd.conf#.
 To enable the daemon during system boot, add a `blacklistd_enable` line to [.filename]#/etc/rc.conf# like this:
 
 [source,shell]
 ....
 # sysrc blacklistd_enable=yes
 ....
 
 To start the service manually, run this command:
 
 [source,shell]
 ....
 # service blacklistd start
 ....
 
 === Creating a Blacklistd Ruleset
 
 Rules for blacklistd are configured in man:blacklistd.conf[5] with one entry per line.
 Each rule contains a tuple separated by spaces or tabs.
 Rules either belong to a `local` or a `remote`, which applies to the machine where blacklistd is running or an outside source, respectively.
 
 ==== Local Rules
 
 An example blacklistd.conf entry for a local rule looks like this:
 
 [.programlisting]
 ....
 [local]
 ssh             stream  *       *               *       3       24h
 ....
 
 All rules that follow the `[local]` section are treated as local rules (which is the default), applying to the local machine.
 When a `[remote]` section is encountered, all rules that follow it are handled as remote machine rules.
 
 Seven fields define a rule separated by either tabs or spaces.
 The first four fields identify the traffic that should be blacklisted.
 The three fields that follow define backlistd's behavior.
 Wildcards are denoted as asterisks (`*`), matching anything in this field.
 The first field defines the location.
 In local rules, these are the network ports.
 The syntax for the location field is as follows:
 
 [.programlisting]
 ....
 [address|interface][/mask][:port]
 ....
 
 Adressses can be specified as IPv4 in numeric format or IPv6 in square brackets.
 An interface name like `_em0_` can also be used.
 
 The socket type is defined by the second field.
 TCP sockets are of type `stream`, whereas UDP is denoted as `dgram`.
 The example above uses TCP, since SSH is using that protocol.
 
 A protocol can be used in the third field of a blacklistd rule.
 The following protocols can be used: `tcp`, `udp`, `tcp6`, `udp6`, or numeric.
 A wildcard, like in the example, is typically used to match all protocols unless there is a reason to distinguish traffic by a certain protocol.
 
 In the fourth field, the effective user or owner of the daemon process that is reporting the event is defined.
 The username or UID can be used here, as well as a wildcard (see example rule above).
 
 The packet filter rule name is declared by the fifth field, which starts the behavior part of the rule.
 By default, blacklistd puts all blocks under a pf anchor called `blacklistd` in [.filename]#pf.conf# like this:
 
 [.programlisting]
 ....
 anchor "blacklistd/*" in on $ext_if
 block in
 pass out
 ....
 
 For separate blacklists, an anchor name can be used in this field.
 In other cases, the wildcard will suffice.
 When a name starts with a hyphen (`-`) it means that an anchor with the default rule name prepended should be used.
 A modified example from the above using the hyphen would look like this:
 
 [.programlisting]
 ....
 ssh             stream  *       *               -ssh       3       24h
 ....
 
 With such a rule, any new blacklist rules are added to an anchor called `blacklistd-ssh`.
 
 To block whole subnets for a single rule violation, a `/` in the rule name can be used.
 This causes the remaining portion of the name to be interpreted as the mask to be applied to the address specified in the rule.
 For example, this rule would block every address adjoining `/24`.
 
 [.programlisting]
 ....
 22              stream  tcp       *               */24    3       24h
 ....
 
 [NOTE]
 ====
 It is important to specify the proper protocol here.
 IPv4 and IPv6 treat /24 differently, that is the reason why `*` cannot be used in the third field for this rule.
 ====
 
 This rule defines that if any one host in that network is misbehaving, everything else on that network will be blocked, too.
 
 The sixth field, called `nfail`, sets the number of login failures required to blacklist the remote IP in question.
 When a wildcard is used at this position, it means that blocks will never happen.
 In the example rule above, a limit of three is defined meaning that after three attempts to log into SSH on one connection, the IP is blocked.
 
 The last field in a blacklistd rule definition specifies how long a host is blacklisted.
 The default unit is seconds, but suffixes like `m`, `h`, and `d` can also be specified for minutes, hours, and days, respectively.
 
 The example rule in its entirety means that after three times authenticating to SSH will result in a new PF block rule for that host.
 Rule matches are performed by first checking local rules one after another, from most specific to least specific.
 When a match occurs, the `remote` rules are applied and the name, `nfail`, and disable fields are changed by the `remote` rule that matched.
 
 ==== Remote Rules
 
 Remote rules are used to specify how blacklistd changes its behavior depending on the remote host currently being evaluated.
 Each field in a remote rule is the same as in a local rule.
 The only difference is in the way blacklistd is using them.
 To explain it, this example rule is used:
 
 [.programlisting]
 ....
 [remote]
 203.0.113.128/25 *      *       *               =/25    =       48h
 ....
 
 The address field can be an IP address (either v4 or v6), a port or both.
 This allows setting special rules for a specific remote address range like in this example.
 The fields for type, protocol and owner are identically interpreted as in the local rule.
 
 The name fields is different though: the equal sign (`=`) in a remote rule tells blacklistd to use the value from the matching local rule.
 It means that the firewall rule entry is taken and the `/25` prefix (a netmask of `255.255.255.128`) is added.
 When a connection from that address range is blacklisted, the entire subnet is affected.
 A PF anchor name can also be used here, in which case blacklistd will add rules for this address block to the anchor of that name.
 The default table is used when a wildcard is specified.
 
 A custom number of failures in the `nfail` column can be defined for an address.
 This is useful for exceptions to a specific rule, to maybe allow someone a less strict application of rules or a bit more leniency in login tries.
 Blocking is disabled when an asterisk is used in this sixth field.
 
 Remote rules allow a stricter enforcement of limits on attempts to log in compared to attempts coming from a local network like an office.
 
 === Blacklistd Client Configuration
 
 There are a few software packages in FreeBSD that can utilize blacklistd's functionality.
 The two most prominent ones are man:ftpd[8] and man:sshd[8] to block excessive connection attempts.
 To activate blacklistd in the SSH daemon, add the following line to [.filename]#/etc/ssh/sshd_config#:
 
 [.programlisting]
 ....
 UseBlacklist yes
 ....
 
 Restart sshd afterwards to make these changes take effect.
 
 Blacklisting for man:ftpd[8] is enabled using `-B`, either in [.filename]#/etc/inetd.conf# or as a flag in [.filename]#/etc/rc.conf# like this:
 
 [.programlisting]
 ....
 ftpd_flags="-B"
 ....
 
 That is all that is needed to make these programs talk to blacklistd.
 
 === Blacklistd Management
 
 Blacklistd provides the user with a management utility called man:blacklistctl[8].
 It displays blocked addresses and networks that are blacklisted by the rules defined in man:blacklistd.conf[5].
 To see the list of currently blocked hosts, use `dump` combined with `-b` like this.
 
 [source,shell]
 ....
 # blacklistctl dump -b
       address/ma:port id      nfail   last access
 213.0.123.128/25:22   OK      6/3     2019/06/08 14:30:19
 ....
 
 This example shows that there were 6 out of three permitted attempts on port 22 coming from the address range `213.0.123.128/25`.
 There are more attempts listed than are allowed because SSH allows a client to try multiple logins on a single TCP connection.
 A connection that is currently going on is not stopped by blacklistd.
 The last connection attempt is listed in the `last access` column of the output.
 
 To see the remaining time that this host will be on the blacklist, add `-r` to the previous command.
 
 [source,shell]
 ....
 # blacklistctl dump -br
       address/ma:port id      nfail   remaining time
 213.0.123.128/25:22   OK      6/3     36s
 ....
 
 In this example, there are 36s seconds left until this host will not be blocked any more.
 
 === Removing Hosts from the Block List
 
 Sometimes it is necessary to remove a host from the block list before the remaining time expires.
 Unfortunately, there is no functionality in blacklistd to do that.
 However, it is possible to remove the address from the PF table using pfctl.
 For each blocked port, there is a child anchor inside the blacklistd anchor defined in [.filename]#/etc/pf.conf#.
 For example, if there is a child anchor for blocking port 22 it is called `blacklistd/22`.
 There is a table inside that child anchor that contains the blocked addresses.
 This table is called port followed by the port number.
 In this example, it would be called `port22`.
 With that information at hand, it is now possible to use man:pfctl[8] to display all addresses listed like this:
 
 [source,shell]
 ....
 # pfctl -a blacklistd/22 -t port22 -T show
 ...
 213.0.123.128/25
 ...
 ....
 
 After identifying the address to be unblocked from the list, the following command removes it from the list:
 
 [source,shell]
 ....
 # pfctl -a blacklistd/22 -t port22 -T delete 213.0.123.128/25
 ....
 
 The address is now removed from PF, but will still show up in the blacklistctl list, since it does not know about any changes made in PF.
 The entry in blacklistd's database will eventually expire and be removed from its output eventually.
 The entry will be added again if the host is matching one of the block rules in blacklistd again.
diff --git a/documentation/content/en/books/handbook/geom/_index.adoc b/documentation/content/en/books/handbook/geom/_index.adoc
index 15bb1134b7..08d3fe6513 100644
--- a/documentation/content/en/books/handbook/geom/_index.adoc
+++ b/documentation/content/en/books/handbook/geom/_index.adoc
@@ -1,1299 +1,1299 @@
 ---
 title: "Chapter 19. GEOM: Modular Disk Transformation Framework"
 part: Part III. System Administration
 prev: books/handbook/disks
 next: books/handbook/zfs
 description: In FreeBSD, the GEOM framework permits access and control to classes, such as Master Boot Records and BSD labels, through the use of providers, or the disk devices in /dev.
 tags: ["GEOM", "RAID", "RAID0", "RAID1", "RAID3", "Striping", "bsdlabel", "newfs", "labelling", "UFS", "journaling"]
 ---
 
 [[geom]]
 = GEOM: Modular Disk Transformation Framework
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 19
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/geom/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/geom/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/geom/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[geom-synopsis]]
 == Synopsis
 
 In FreeBSD, the GEOM framework permits access and control to classes, such as Master Boot Records and BSD labels, through the use of providers, or the disk devices in [.filename]#/dev#.
 By supporting various software RAID configurations, GEOM transparently provides access to the operating system and operating system utilities.
 
 This chapter covers the use of disks under the GEOM framework in FreeBSD.
 This includes the major RAID control utilities which use the framework for configuration.
 This chapter is not a definitive guide to RAID configurations and only GEOM-supported RAID classifications are discussed.
 
 After reading this chapter, you will know:
 
 * What type of RAID support is available through GEOM.
 * How to use the base utilities to configure, maintain, and manipulate the various RAID levels.
 * How to mirror, stripe, encrypt, and remotely connect disk devices through GEOM.
 * How to troubleshoot disks attached to the GEOM framework.
 
 Before reading this chapter, you should:
 
 * Understand how FreeBSD treats disk devices (crossref:disks[disks,Storage]).
 * Know how to configure and install a new kernel (crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel]).
 
 [[geom-striping]]
 == RAID0 - Striping
 
 Striping combines several disk drives into a single volume.
 Striping can be performed through the use of hardware RAID controllers.
 The GEOM disk subsystem provides software support for disk striping, also known as RAID0, without the need for a RAID disk controller.
 
 In RAID0, data is split into blocks that are written across all the drives in the array.
 As seen in the following illustration, instead of having to wait on the system to write 256k to one disk, RAID0 can simultaneously write 64k to each of the four disks in the array, offering superior I/O performance.
 This performance can be enhanced further by using multiple disk controllers.
 
 image::striping.png[Disk Striping Illustration]
 
 Each disk in a RAID0 stripe must be of the same size, since I/O requests are interleaved to read or write to multiple disks in parallel.
 
 [NOTE]
 ====
 RAID0 does _not_ provide any redundancy.
 This means that if one disk in the array fails, all of the data on the disks is lost.
 If the data is important, implement a backup strategy that regularly saves backups to a remote system or device.
 ====
 
 The process for creating a software, GEOM-based RAID0 on a FreeBSD system using commodity disks is as follows.
 Once the stripe is created, refer to man:gstripe[8] for more information on how to control an existing stripe.
 
 [.procedure]
 ****
 *Procedure: Creating a Stripe of Unformatted ATA Disks*
 
 . Load the [.filename]#geom_stripe.ko# module:
 +
 [source,shell]
 ....
 # kldload geom_stripe
 ....
 
 . Ensure that a suitable mount point exists. If this volume will become a root partition, then temporarily use another mount point such as [.filename]#/mnt#.
 . Determine the device names for the disks which will be striped, and create the new stripe device. For example, to stripe two unused and unpartitioned ATA disks with device names of [.filename]#/dev/ad2# and [.filename]#/dev/ad3#:
 +
 [source,shell]
 ....
 # gstripe label -v st0 /dev/ad2 /dev/ad3
 Metadata value stored on /dev/ad2.
 Metadata value stored on /dev/ad3.
 Done.
 ....
 
 . Write a standard label, also known as a partition table, on the new volume and install the default bootstrap code:
 +
 [source,shell]
 ....
 # bsdlabel -wB /dev/stripe/st0
 ....
 
 . This process should create two other devices in [.filename]#/dev/stripe# in addition to [.filename]#st0#. Those include [.filename]#st0a# and [.filename]#st0c#. At this point, a UFS file system can be created on [.filename]#st0a# using `newfs`:
 +
 [source,shell]
 ....
 # newfs -U /dev/stripe/st0a
 ....
-+ 
++
 Many numbers will glide across the screen, and after a few seconds, the process will be complete.
 The volume has been created and is ready to be mounted.
 . To manually mount the created disk stripe:
 +
 [source,shell]
 ....
 # mount /dev/stripe/st0a /mnt
 ....
 
 . To mount this striped file system automatically during the boot process, place the volume information in [.filename]#/etc/fstab#. In this example, a permanent mount point, named [.filename]#stripe#, is created:
 +
 [source,shell]
 ....
 # mkdir /stripe
 # echo "/dev/stripe/st0a /stripe ufs rw 2 2" \
 >> /etc/fstab
 ....
 
 . The [.filename]#geom_stripe.ko# module must also be automatically loaded during system initialization, by adding a line to [.filename]#/boot/loader.conf#:
 +
 [source,shell]
 ....
 # echo 'geom_stripe_load="YES"' >> /boot/loader.conf
 ....
 ****
 
 [[geom-mirror]]
 == RAID1 - Mirroring
 
 RAID1, or _mirroring_, is the technique of writing the same data to more than one disk drive.
 Mirrors are usually used to guard against data loss due to drive failure.
 Each drive in a mirror contains an identical copy of the data.
 When an individual drive fails, the mirror continues to work, providing data from the drives that are still functioning.
 The computer keeps running, and the administrator has time to replace the failed drive without user interruption.
 
 Two common situations are illustrated in these examples.
 The first creates a mirror out of two new drives and uses it as a replacement for an existing single drive.
 The second example creates a mirror on a single new drive, copies the old drive's data to it, then inserts the old drive into the mirror.
 While this procedure is slightly more complicated, it only requires one new drive.
 
 Traditionally, the two drives in a mirror are identical in model and capacity, but man:gmirror[8] does not require that.
 Mirrors created with dissimilar drives will have a capacity equal to that of the smallest drive in the mirror.
 Extra space on larger drives will be unused.
 Drives inserted into the mirror later must have at least as much capacity as the smallest drive already in the mirror.
 
 [WARNING]
 ====
 The mirroring procedures shown here are non-destructive, but as with any major disk operation, make a full backup first.
 ====
 
 [WARNING]
 ====
 While man:dump[8] is used in these procedures to copy file systems, it does not work on file systems with soft updates journaling.
 See man:tunefs[8] for information on detecting and disabling soft updates journaling.
 ====
 
 [[geom-mirror-metadata]]
 === Metadata Issues
 
 Many disk systems store metadata at the end of each disk.
 Old metadata should be erased before reusing the disk for a mirror.
 Most problems are caused by two particular types of leftover metadata: GPT partition tables and old metadata from a previous mirror.
 
 GPT metadata can be erased with man:gpart[8].
 This example erases both primary and backup GPT partition tables from disk [.filename]#ada8#:
 
 [source,shell]
 ....
 # gpart destroy -F ada8
 ....
 
 A disk can be removed from an active mirror and the metadata erased in one step using man:gmirror[8].
 Here, the example disk [.filename]#ada8# is removed from the active mirror [.filename]#gm4#:
 
 [source,shell]
 ....
 # gmirror remove gm4 ada8
 ....
 
 If the mirror is not running, but old mirror metadata is still on the disk, use `gmirror clear` to remove it:
 
 [source,shell]
 ....
 # gmirror clear ada8
 ....
 
 man:gmirror[8] stores one block of metadata at the end of the disk.
 As GPT partition schemes also store metadata at the end of the disk, mirroring entire GPT disks with man:gmirror[8] is not recommended.
 MBR partitioning is used here because it only stores a partition table at the start of the disk and does not conflict with the mirror metadata.
 
 [[geom-mirror-two-new-disks]]
 === Creating a Mirror with Two New Disks
 
 In this example, FreeBSD has already been installed on a single disk, [.filename]#ada0#.
 Two new disks, [.filename]#ada1# and [.filename]#ada2#, have been connected to the system.
 A new mirror will be created on these two disks and used to replace the old single disk.
 
 The [.filename]#geom_mirror.ko# kernel module must either be built into the kernel or loaded at boot- or run-time.
 Manually load the kernel module now:
 
 [source,shell]
 ....
 # gmirror load
 ....
 
 Create the mirror with the two new drives:
 
 [source,shell]
 ....
 # gmirror label -v gm0 /dev/ada1 /dev/ada2
 ....
 
 [.filename]#gm0# is a user-chosen device name assigned to the new mirror.
 After the mirror has been started, this device name appears in [.filename]#/dev/mirror/#.
 
 MBR and bsdlabel partition tables can now be created on the mirror with man:gpart[8].
 This example uses a traditional file system layout, with partitions for [.filename]#/#, swap, [.filename]#/var#, [.filename]#/tmp#, and [.filename]#/usr#. 
 A single [.filename]#/# and a swap partition will also work.
 
 Partitions on the mirror do not have to be the same size as those on the existing disk, but they must be large enough to hold all the data already present on [.filename]#ada0#.
 
 [source,shell]
 ....
 # gpart create -s MBR mirror/gm0
 # gpart add -t freebsd -a 4k mirror/gm0
 # gpart show mirror/gm0
 =>       63  156301423  mirror/gm0  MBR  (74G)
          63         63                    - free -  (31k)
         126  156301299                 1  freebsd  (74G)
   156301425         61                    - free -  (30k)
 ....
 
 [source,shell]
 ....
 # gpart create -s BSD mirror/gm0s1
 # gpart add -t freebsd-ufs  -a 4k -s 2g mirror/gm0s1
 # gpart add -t freebsd-swap -a 4k -s 4g mirror/gm0s1
 # gpart add -t freebsd-ufs  -a 4k -s 2g mirror/gm0s1
 # gpart add -t freebsd-ufs  -a 4k -s 1g mirror/gm0s1
 # gpart add -t freebsd-ufs  -a 4k mirror/gm0s1
 # gpart show mirror/gm0s1
 =>        0  156301299  mirror/gm0s1  BSD  (74G)
           0          2                      - free -  (1.0k)
           2    4194304                   1  freebsd-ufs  (2.0G)
     4194306    8388608                   2  freebsd-swap (4.0G)
    12582914    4194304                   4  freebsd-ufs  (2.0G)
    16777218    2097152                   5  freebsd-ufs  (1.0G)
    18874370  137426928                   6  freebsd-ufs  (65G)
   156301298          1                      - free -  (512B)
 ....
 
 Make the mirror bootable by installing bootcode in the MBR and bsdlabel and setting the active slice:
 
 [source,shell]
 ....
 # gpart bootcode -b /boot/mbr mirror/gm0
 # gpart set -a active -i 1 mirror/gm0
 # gpart bootcode -b /boot/boot mirror/gm0s1
 ....
 
 Format the file systems on the new mirror, enabling soft-updates.
 
 [source,shell]
 ....
 # newfs -U /dev/mirror/gm0s1a
 # newfs -U /dev/mirror/gm0s1d
 # newfs -U /dev/mirror/gm0s1e
 # newfs -U /dev/mirror/gm0s1f
 ....
 
 File systems from the original [.filename]#ada0# disk can now be copied onto the mirror with man:dump[8] and man:restore[8].
 
 [source,shell]
 ....
 # mount /dev/mirror/gm0s1a /mnt
 # dump -C16 -b64 -0aL -f - / | (cd /mnt && restore -rf -)
 # mount /dev/mirror/gm0s1d /mnt/var
 # mount /dev/mirror/gm0s1e /mnt/tmp
 # mount /dev/mirror/gm0s1f /mnt/usr
 # dump -C16 -b64 -0aL -f - /var | (cd /mnt/var && restore -rf -)
 # dump -C16 -b64 -0aL -f - /tmp | (cd /mnt/tmp && restore -rf -)
 # dump -C16 -b64 -0aL -f - /usr | (cd /mnt/usr && restore -rf -)
 ....
 
 Edit [.filename]#/mnt/etc/fstab# to point to the new mirror file systems:
 
 [.programlisting]
 ....
 # Device		Mountpoint	FStype	Options	Dump	Pass#
 /dev/mirror/gm0s1a	/		ufs	rw	1	1
 /dev/mirror/gm0s1b	none		swap	sw	0	0
 /dev/mirror/gm0s1d	/var		ufs	rw	2	2
 /dev/mirror/gm0s1e	/tmp		ufs	rw	2	2
 /dev/mirror/gm0s1f	/usr		ufs	rw	2	2
 ....
 
 If the [.filename]#geom_mirror.ko# kernel module has not been built into the kernel, [.filename]#/mnt/boot/loader.conf# is edited to load the module at boot:
 
 [.programlisting]
 ....
 geom_mirror_load="YES"
 ....
 
 Reboot the system to test the new mirror and verify that all data has been copied.
 The BIOS will see the mirror as two individual drives rather than a mirror.
 Since the drives are identical, it does not matter which is selected to boot.
 
 See <<gmirror-troubleshooting>> if there are problems booting.
 Powering down and disconnecting the original [.filename]#ada0# disk will allow it to be kept as an offline backup.
 
 In use, the mirror will behave just like the original single drive.
 
 [[geom-mirror-existing-drive]]
 === Creating a Mirror with an Existing Drive
 
 In this example, FreeBSD has already been installed on a single disk, [.filename]#ada0#.
 A new disk, [.filename]#ada1#, has been connected to the system.
 A one-disk mirror will be created on the new disk, the existing system copied onto it, and then the old disk will be inserted into the mirror.
 This slightly complex procedure is required because `gmirror` needs to put a 512-byte block of metadata at the end of each disk, and the existing [.filename]#ada0# has usually had all of its space already allocated.
 
 Load the [.filename]#geom_mirror.ko# kernel module:
 
 [source,shell]
 ....
 # gmirror load
 ....
 
 Check the media size of the original disk with `diskinfo`:
 
 [source,shell]
 ....
 # diskinfo -v ada0 | head -n3
 /dev/ada0
         512             # sectorsize
         1000204821504   # mediasize in bytes (931G)
 ....
 
 Create a mirror on the new disk.
 To make certain that the mirror capacity is not any larger than the original [.filename]#ada0# drive, man:gnop[8] is used to create a fake drive of the exact same size.
 This drive does not store any data, but is used only to limit the size of the mirror.
 When man:gmirror[8] creates the mirror, it will restrict the capacity to the size of [.filename]#gzero.nop#, even if the new [.filename]#ada1# drive has more space.
 Note that the _1000204821504_ in the second line is equal to [.filename]#ada0#'s media size as shown by `diskinfo` above.
 
 [source,shell]
 ....
 # geom zero load
 # gnop create -s 1000204821504 gzero
 # gmirror label -v gm0 gzero.nop ada1
 # gmirror forget gm0
 ....
 
 Since [.filename]#gzero.nop# does not store any data, the mirror does not see it as connected.
 The mirror is told to "forget" unconnected components, removing references to [.filename]#gzero.nop#.
 The result is a mirror device containing only a single disk, [.filename]#ada1#.
 
 After creating [.filename]#gm0#, view the partition table on [.filename]#ada0#.
 This output is from a 1 TB drive.
 If there is some unallocated space at the end of the drive, the contents may be copied directly from [.filename]#ada0# to the new mirror.
 
 However, if the output shows that all of the space on the disk is allocated, as in the following listing, there is no space available for the 512-byte mirror metadata at the end of the disk.
 
 [source,shell]
 ....
 # gpart show ada0
 =>        63  1953525105        ada0  MBR  (931G)
           63  1953525105           1  freebsd  [active]  (931G)
 ....
 
 In this case, the partition table must be edited to reduce the capacity by one sector on [.filename]#mirror/gm0#.
 The procedure will be explained later.
 
 In either case, partition tables on the primary disk should be first copied using `gpart backup` and `gpart restore`.
 
 [source,shell]
 ....
 # gpart backup ada0 > table.ada0
 # gpart backup ada0s1 > table.ada0s1
 ....
 
 These commands create two files, [.filename]#table.ada0# and [.filename]#table.ada0s1#.
 This example is from a 1 TB drive:
 
 [source,shell]
 ....
 # cat table.ada0
 MBR 4
 1 freebsd         63 1953525105   [active]
 ....
 
 [source,shell]
 ....
 # cat table.ada0s1
 BSD 8
 1  freebsd-ufs          0    4194304
 2 freebsd-swap    4194304   33554432
 4  freebsd-ufs   37748736   50331648
 5  freebsd-ufs   88080384   41943040
 6  freebsd-ufs  130023424  838860800
 7  freebsd-ufs  968884224  984640881
 ....
 
 If no free space is shown at the end of the disk, the size of both the slice and the last partition must be reduced by one sector.
 Edit the two files, reducing the size of both the slice and last partition by one.
 These are the last numbers in each listing.
 
 [source,shell]
 ....
 # cat table.ada0
 MBR 4
 1 freebsd         63 1953525104   [active]
 ....
 
 [source,shell]
 ....
 # cat table.ada0s1
 BSD 8
 1  freebsd-ufs          0    4194304
 2 freebsd-swap    4194304   33554432
 4  freebsd-ufs   37748736   50331648
 5  freebsd-ufs   88080384   41943040
 6  freebsd-ufs  130023424  838860800
 7  freebsd-ufs  968884224  984640880
 ....
 
 If at least one sector was unallocated at the end of the disk, these two files can be used without modification.
 
 Now restore the partition table into [.filename]#mirror/gm0#:
 
 [source,shell]
 ....
 # gpart restore mirror/gm0 < table.ada0
 # gpart restore mirror/gm0s1 < table.ada0s1
 ....
 
 Check the partition table with `gpart show`.
 This example has [.filename]#gm0s1a# for [.filename]#/#, [.filename]#gm0s1d# for [.filename]#/var#, [.filename]#gm0s1e# for [.filename]#/usr#, [.filename]#gm0s1f# for [.filename]#/data1#, and [.filename]#gm0s1g# for [.filename]#/data2#.
 
 [source,shell]
 ....
 # gpart show mirror/gm0
 =>        63  1953525104  mirror/gm0  MBR  (931G)
           63  1953525042           1  freebsd  [active]  (931G)
   1953525105          62              - free -  (31k)
 
 # gpart show mirror/gm0s1
 =>         0  1953525042  mirror/gm0s1  BSD  (931G)
            0     2097152             1  freebsd-ufs  (1.0G)
      2097152    16777216             2  freebsd-swap  (8.0G)
     18874368    41943040             4  freebsd-ufs  (20G)
     60817408    20971520             5  freebsd-ufs  (10G)
     81788928   629145600             6  freebsd-ufs  (300G)
    710934528  1242590514             7  freebsd-ufs  (592G)
   1953525042          63                - free -  (31k)
 ....
 
 Both the slice and the last partition must have at least one free block at the end of the disk.
 
 Create file systems on these new partitions.
 The number of partitions will vary to match the original disk, [.filename]#ada0#.
 
 [source,shell]
 ....
 # newfs -U /dev/mirror/gm0s1a
 # newfs -U /dev/mirror/gm0s1d
 # newfs -U /dev/mirror/gm0s1e
 # newfs -U /dev/mirror/gm0s1f
 # newfs -U /dev/mirror/gm0s1g
 ....
 
 Make the mirror bootable by installing bootcode in the MBR and bsdlabel and setting the active slice:
 
 [source,shell]
 ....
 # gpart bootcode -b /boot/mbr mirror/gm0
 # gpart set -a active -i 1 mirror/gm0
 # gpart bootcode -b /boot/boot mirror/gm0s1
 ....
 
 Adjust [.filename]#/etc/fstab# to use the new partitions on the mirror.
 Back up this file first by copying it to [.filename]#/etc/fstab.orig#.
 
 [source,shell]
 ....
 # cp /etc/fstab /etc/fstab.orig
 ....
 
 Edit [.filename]#/etc/fstab#, replacing [.filename]#/dev/ada0# with [.filename]#mirror/gm0#.
 
 [.programlisting]
 ....
 # Device		Mountpoint	FStype	Options	Dump	Pass#
 /dev/mirror/gm0s1a	/		ufs	rw	1	1
 /dev/mirror/gm0s1b	none		swap	sw	0	0
 /dev/mirror/gm0s1d	/var		ufs	rw	2	2
 /dev/mirror/gm0s1e	/usr		ufs	rw	2	2
 /dev/mirror/gm0s1f	/data1		ufs	rw	2	2
 /dev/mirror/gm0s1g	/data2		ufs	rw	2	2
 ....
 
 If the [.filename]#geom_mirror.ko# kernel module has not been built into the kernel, edit [.filename]#/boot/loader.conf# to load it at boot:
 
 [.programlisting]
 ....
 geom_mirror_load="YES"
 ....
 
 File systems from the original disk can now be copied onto the mirror with man:dump[8] and man:restore[8].
 Each file system dumped with `dump -L` will create a snapshot first, which can take some time.
 
 [source,shell]
 ....
 # mount /dev/mirror/gm0s1a /mnt
 # dump -C16 -b64 -0aL -f - /    | (cd /mnt && restore -rf -)
 # mount /dev/mirror/gm0s1d /mnt/var
 # mount /dev/mirror/gm0s1e /mnt/usr
 # mount /dev/mirror/gm0s1f /mnt/data1
 # mount /dev/mirror/gm0s1g /mnt/data2
 # dump -C16 -b64 -0aL -f - /usr | (cd /mnt/usr && restore -rf -)
 # dump -C16 -b64 -0aL -f - /var | (cd /mnt/var && restore -rf -)
 # dump -C16 -b64 -0aL -f - /data1 | (cd /mnt/data1 && restore -rf -)
 # dump -C16 -b64 -0aL -f - /data2 | (cd /mnt/data2 && restore -rf -)
 ....
 
 Restart the system, booting from [.filename]#ada1#.
 If everything is working, the system will boot from [.filename]#mirror/gm0#, which now contains the same data as [.filename]#ada0# had previously. 
 See <<gmirror-troubleshooting>> if there are problems booting.
 
 At this point, the mirror still consists of only the single [.filename]#ada1# disk.
 
 After booting from [.filename]#mirror/gm0# successfully, the final step is inserting [.filename]#ada0# into the mirror.
 
 [IMPORTANT]
 ====
 When [.filename]#ada0# is inserted into the mirror, its former contents will be overwritten by data from the mirror.
 Make certain that [.filename]#mirror/gm0# has the same contents as [.filename]#ada0# before adding [.filename]#ada0# to the mirror.
 If the contents previously copied by man:dump[8] and man:restore[8] are not identical to what was on [.filename]#ada0#, revert [.filename]#/etc/fstab# to mount the file systems on [.filename]#ada0#, reboot, and start the whole procedure again.
 ====
 
 [source,shell]
 ....
 # gmirror insert gm0 ada0
 GEOM_MIRROR: Device gm0: rebuilding provider ada0
 ....
 
 Synchronization between the two disks will start immediately.
 Use `gmirror status` to view the progress.
 
 [source,shell]
 ....
 # gmirror status
       Name    Status  Components
 girror/gm0  DEGRADED  ada1 (ACTIVE)
                       ada0 (SYNCHRONIZING, 64%)
 ....
 
 After a while, synchronization will finish.
 
 [source,shell]
 ....
 GEOM_MIRROR: Device gm0: rebuilding provider ada0 finished.
 # gmirror status
       Name    Status  Components
 mirror/gm0  COMPLETE  ada1 (ACTIVE)
                       ada0 (ACTIVE)
 ....
 
 [.filename]#mirror/gm0# now consists of the two disks [.filename]#ada0# and [.filename]#ada1#, and the contents are automatically synchronized with each other.
 In use, [.filename]#mirror/gm0# will behave just like the original single drive.
 
 [[gmirror-troubleshooting]]
 === Troubleshooting
 
 If the system no longer boots, BIOS settings may have to be changed to boot from one of the new mirrored drives.
 Either mirror drive can be used for booting, as they contain identical data.
 
 If the boot stops with this message, something is wrong with the mirror device:
 
 [source,shell]
 ....
 Mounting from ufs:/dev/mirror/gm0s1a failed with error 19.
 
 Loader variables:
   vfs.root.mountfrom=ufs:/dev/mirror/gm0s1a
   vfs.root.mountfrom.options=rw
 
 Manual root filesystem specification:
   <fstype>:<device> [options]
       Mount <device> using filesystem <fstype>
       and with the specified (optional) option list.
 
     eg. ufs:/dev/da0s1a
         zfs:tank
         cd9660:/dev/acd0 ro
           (which is equivalent to: mount -t cd9660 -o ro /dev/acd0 /)
 
   ?               List valid disk boot devices
   .               Yield 1 second (for background tasks)
   <empty line>    Abort manual input
 
 mountroot>
 ....
 
 Forgetting to load the [.filename]#geom_mirror.ko# module in [.filename]#/boot/loader.conf# can cause this problem.
 To fix it, boot from a FreeBSD installation media and choose `Shell` at the first prompt.
 Then load the mirror module and mount the mirror device:
 
 [source,shell]
 ....
 # gmirror load
 # mount /dev/mirror/gm0s1a /mnt
 ....
 
 Edit [.filename]#/mnt/boot/loader.conf#, adding a line to load the mirror module:
 
 [.programlisting]
 ....
 geom_mirror_load="YES"
 ....
 
 Save the file and reboot.
 
 Other problems that cause `error 19` require more effort to fix.
 Although the system should boot from [.filename]#ada0#, another prompt to select a shell will appear if [.filename]#/etc/fstab# is incorrect.
 Enter `ufs:/dev/ada0s1a` at the boot loader prompt and press kbd:[Enter].
 Undo the edits in [.filename]#/etc/fstab# then mount the file systems from the original disk ([.filename]#ada0#) instead of the mirror.
 Reboot the system and try the procedure again.
 
 [source,shell]
 ....
 Enter full pathname of shell or RETURN for /bin/sh:
 # cp /etc/fstab.orig /etc/fstab
 # reboot
 ....
 
 === Recovering from Disk Failure
 
 The benefit of disk mirroring is that an individual disk can fail without causing the mirror to lose any data.
 In the above example, if [.filename]#ada0# fails, the mirror will continue to work, providing data from the remaining working drive, [.filename]#ada1#.
 
 To replace the failed drive, shut down the system and physically replace the failed drive with a new drive of equal or greater capacity.
 Manufacturers use somewhat arbitrary values when rating drives in gigabytes, and the only way to really be sure is to compare the total count of sectors shown by `diskinfo -v`.
 A drive with larger capacity than the mirror will work, although the extra space on the new drive will not be used.
 
 After the computer is powered back up, the mirror will be running in a "degraded" mode with only one drive.
 The mirror is told to forget drives that are not currently connected:
 
 [source,shell]
 ....
 # gmirror forget gm0
 ....
 
 Any old metadata should be cleared from the replacement disk using the instructions in <<geom-mirror-metadata>>.
 Then the replacement disk, [.filename]#ada4# for this example, is inserted into the mirror:
 
 [source,shell]
 ....
 # gmirror insert gm0 /dev/ada4
 ....
 
 Resynchronization begins when the new drive is inserted into the mirror.
 This process of copying mirror data to a new drive can take a while.
 Performance of the mirror will be greatly reduced during the copy, so inserting new drives is best done when there is low demand on the computer.
 
 Progress can be monitored with `gmirror status`, which shows drives that are being synchronized and the percentage of completion.
 During resynchronization, the status will be `DEGRADED`, changing to `COMPLETE` when the process is finished.
 
 [[geom-raid3]]
 == RAID3 - Byte-level Striping with Dedicated Parity
 
 RAID3 is a method used to combine several disk drives into a single volume with a dedicated parity disk.
 In a RAID3 system, data is split up into a number of bytes that are written across all the drives in the array except for one disk which acts as a dedicated parity disk.
 This means that disk reads from a RAID3 implementation access all disks in the array.
 Performance can be enhanced by using multiple disk controllers.
 The RAID3 array provides a fault tolerance of 1 drive, while providing a capacity of 1 - 1/n times the total capacity of all drives in the array, where n is the number of hard drives in the array.
 Such a configuration is mostly suitable for storing data of larger sizes such as multimedia files.
 
 At least 3 physical hard drives are required to build a RAID3 array.
 Each disk must be of the same size, since I/O requests are interleaved to read or write to multiple disks in parallel.
 Also, due to the nature of RAID3, the number of drives must be equal to 3, 5, 9, 17, and so on, or 2^n + 1.
 
 This section demonstrates how to create a software RAID3 on a FreeBSD system.
 
 [NOTE]
 ====
 While it is theoretically possible to boot from a RAID3 array on FreeBSD, that configuration is uncommon and is not advised.
 ====
 
 === Creating a Dedicated RAID3 Array
 
 In FreeBSD, support for RAID3 is implemented by the man:graid3[8] GEOM class.
 Creating a dedicated RAID3 array on FreeBSD requires the following steps.
 
 [.procedure]
 . First, load the [.filename]#geom_raid3.ko# kernel module by issuing one of the following commands:
 +
 [source,shell]
 ....
 # graid3 load
 ....
-+ 
++
 or:
 +
 [source,shell]
 ....
 # kldload geom_raid3
 ....
 
 . Ensure that a suitable mount point exists. This command creates a new directory to use as the mount point:
 +
 [source,shell]
 ....
 # mkdir /multimedia
 ....
 
 . Determine the device names for the disks which will be added to the array, and create the new RAID3 device. The final device listed will act as the dedicated parity disk. This example uses three unpartitioned ATA drives: [.filename]#ada1# and [.filename]#ada2# for data, and [.filename]#ada3# for parity.
 +
 [source,shell]
 ....
 # graid3 label -v gr0 /dev/ada1 /dev/ada2 /dev/ada3
 Metadata value stored on /dev/ada1.
 Metadata value stored on /dev/ada2.
 Metadata value stored on /dev/ada3.
 Done.
 ....
 
 . Partition the newly created [.filename]#gr0# device and put a UFS file system on it:
 +
 [source,shell]
 ....
 # gpart create -s GPT /dev/raid3/gr0
 # gpart add -t freebsd-ufs /dev/raid3/gr0
 # newfs -j /dev/raid3/gr0p1
 ....
-+ 
++
 Many numbers will glide across the screen, and after a bit of time, the process will be complete.
 The volume has been created and is ready to be mounted:
 +
 [source,shell]
 ....
 # mount /dev/raid3/gr0p1 /multimedia/
 ....
-+ 
++
 The RAID3 array is now ready to use.
 
 Additional configuration is needed to retain this setup across system reboots.
 
 [.procedure]
 . The [.filename]#geom_raid3.ko# module must be loaded before the array can be mounted. To automatically load the kernel module during system initialization, add the following line to [.filename]#/boot/loader.conf#:
 +
 [.programlisting]
 ....
 geom_raid3_load="YES"
 ....
 
 . The following volume information must be added to [.filename]#/etc/fstab# in order to automatically mount the array's file system during the system boot process:
 +
 [.programlisting]
 ....
 /dev/raid3/gr0p1	/multimedia	ufs	rw	2	2
 ....
 
 [[geom-graid]]
 == Software RAID Devices
 
 Some motherboards and expansion cards add some simple hardware, usually just a ROM, that allows the computer to boot from a RAID array.
 After booting, access to the RAID array is handled by software running on the computer's main processor.
 This "hardware-assisted software RAID" gives RAID arrays that are not dependent on any particular operating system, and which are functional even before an operating system is loaded.
 
 Several levels of RAID are supported, depending on the hardware in use.
 See man:graid[8] for a complete list.
 
 man:graid[8] requires the [.filename]#geom_raid.ko# kernel module, which is included in the [.filename]#GENERIC# kernel starting with FreeBSD 9.1.
 If needed, it can be loaded manually with `graid load`.
 
 [[geom-graid-creating]]
 === Creating an Array
 
 Software RAID devices often have a menu that can be entered by pressing special keys when the computer is booting.
 The menu can be used to create and delete RAID arrays.
 man:graid[8] can also create arrays directly from the command line.
 
 `graid label` is used to create a new array.
 The motherboard used for this example has an Intel software RAID chipset, so the Intel metadata format is specified.
 The new array is given a label of [.filename]#gm0#, it is a mirror (RAID1), and uses drives [.filename]#ada0# and [.filename]#ada1#.
 
 [CAUTION]
 ====
 Some space on the drives will be overwritten when they are made into a new array.
 Back up existing data first!
 ====
 
 [source,shell]
 ....
 # graid label Intel gm0 RAID1 ada0 ada1
 GEOM_RAID: Intel-a29ea104: Array Intel-a29ea104 created.
 GEOM_RAID: Intel-a29ea104: Disk ada0 state changed from NONE to ACTIVE.
 GEOM_RAID: Intel-a29ea104: Subdisk gm0:0-ada0 state changed from NONE to ACTIVE.
 GEOM_RAID: Intel-a29ea104: Disk ada1 state changed from NONE to ACTIVE.
 GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 state changed from NONE to ACTIVE.
 GEOM_RAID: Intel-a29ea104: Array started.
 GEOM_RAID: Intel-a29ea104: Volume gm0 state changed from STARTING to OPTIMAL.
 Intel-a29ea104 created
 GEOM_RAID: Intel-a29ea104: Provider raid/r0 for volume gm0 created.
 ....
 
 A status check shows the new mirror is ready for use:
 
 [source,shell]
 ....
 # graid status
    Name   Status  Components
 raid/r0  OPTIMAL  ada0 (ACTIVE (ACTIVE))
                   ada1 (ACTIVE (ACTIVE))
 ....
 
 The array device appears in [.filename]#/dev/raid/#.
 The first array is called [.filename]#r0#.
 Additional arrays, if present, will be [.filename]#r1#, [.filename]#r2#, and so on.
 
 The BIOS menu on some of these devices can create arrays with special characters in their names.
 To avoid problems with those special characters, arrays are given simple numbered names like [.filename]#r0#.
 To show the actual labels, like [.filename]#gm0# in the example above, use man:sysctl[8]:
 
 [source,shell]
 ....
 # sysctl kern.geom.raid.name_format=1
 ....
 
 [[geom-graid-volumes]]
 === Multiple Volumes
 
 Some software RAID devices support more than one _volume_ on an array.
 Volumes work like partitions, allowing space on the physical drives to be split and used in different ways.
 For example, Intel software RAID devices support two volumes.
 This example creates a 40 G mirror for safely storing the operating system, followed by a 20 G RAID0 (stripe) volume for fast temporary storage:
 
 [source,shell]
 ....
 # graid label -S 40G Intel gm0 RAID1 ada0 ada1
 # graid add -S 20G gm0 RAID0
 ....
 
 Volumes appear as additional [.filename]#rX# entries in [.filename]#/dev/raid/#.
 An array with two volumes will show [.filename]#r0# and [.filename]#r1#.
 
 See man:graid[8] for the number of volumes supported by different software RAID devices.
 
 [[geom-graid-converting]]
 === Converting a Single Drive to a Mirror
 
 Under certain specific conditions, it is possible to convert an existing single drive to a man:graid[8] array without reformatting.
 To avoid data loss during the conversion, the existing drive must meet these minimum requirements:
 
 * The drive must be partitioned with the MBR partitioning scheme. GPT or other partitioning schemes with metadata at the end of the drive will be overwritten and corrupted by the man:graid[8] metadata.
 * There must be enough unpartitioned and unused space at the end of the drive to hold the man:graid[8] metadata. This metadata varies in size, but the largest occupies 64 M, so at least that much free space is recommended.
 
 If the drive meets these requirements, start by making a full backup.
 Then create a single-drive mirror with that drive:
 
 [source,shell]
 ....
 # graid label Intel gm0 RAID1 ada0 NONE
 ....
 
 man:graid[8] metadata was written to the end of the drive in the unused space.
 A second drive can now be inserted into the mirror:
 
 [source,shell]
 ....
 # graid insert raid/r0 ada1
 ....
 
 Data from the original drive will immediately begin to be copied to the second drive.
 The mirror will operate in degraded status until the copy is complete.
 
 [[geom-graid-inserting]]
 === Inserting New Drives into the Array
 
 Drives can be inserted into an array as replacements for drives that have failed or are missing.
 If there are no failed or missing drives, the new drive becomes a spare.
 For example, inserting a new drive into a working two-drive mirror results in a two-drive mirror with one spare drive, not a three-drive mirror.
 
 In the example mirror array, data immediately begins to be copied to the newly-inserted drive.
 Any existing information on the new drive will be overwritten.
 
 [source,shell]
 ....
 # graid insert raid/r0 ada1
 GEOM_RAID: Intel-a29ea104: Disk ada1 state changed from NONE to ACTIVE.
 GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 state changed from NONE to NEW.
 GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 state changed from NEW to REBUILD.
 GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 rebuild start at 0.
 ....
 
 [[geom-graid-removing]]
 === Removing Drives from the Array
 
 Individual drives can be permanently removed from a from an array and their metadata erased:
 
 [source,shell]
 ....
 # graid remove raid/r0 ada1
 GEOM_RAID: Intel-a29ea104: Disk ada1 state changed from ACTIVE to OFFLINE.
 GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-[unknown] state changed from ACTIVE to NONE.
 GEOM_RAID: Intel-a29ea104: Volume gm0 state changed from OPTIMAL to DEGRADED.
 ....
 
 [[geom-graid-stopping]]
 === Stopping the Array
 
 An array can be stopped without removing metadata from the drives.
 The array will be restarted when the system is booted.
 
 [source,shell]
 ....
 # graid stop raid/r0
 ....
 
 [[geom-graid-status]]
 === Checking Array Status
 
 Array status can be checked at any time.
 After a drive was added to the mirror in the example above, data is being copied from the original drive to the new drive:
 
 [source,shell]
 ....
 # graid status
    Name    Status  Components
 raid/r0  DEGRADED  ada0 (ACTIVE (ACTIVE))
                    ada1 (ACTIVE (REBUILD 28%))
 ....
 
 Some types of arrays, like `RAID0` or `CONCAT`, may not be shown in the status report if disks have failed.
 To see these partially-failed arrays, add `-ga`:
 
 [source,shell]
 ....
 # graid status -ga
           Name  Status  Components
 Intel-e2d07d9a  BROKEN  ada6 (ACTIVE (ACTIVE))
 ....
 
 [[geom-graid-deleting]]
 === Deleting Arrays
 
 Arrays are destroyed by deleting all of the volumes from them.
 When the last volume present is deleted, the array is stopped and metadata is removed from the drives:
 
 [source,shell]
 ....
 # graid delete raid/r0
 ....
 
 [[geom-graid-unexpected]]
 === Deleting Unexpected Arrays
 
 Drives may unexpectedly contain man:graid[8] metadata, either from previous use or manufacturer testing.
 man:graid[8] will detect these drives and create an array, interfering with access to the individual drive.
 To remove the unwanted metadata:
 
 [.procedure]
 . Boot the system. At the boot menu, select `2` for the loader prompt. Enter:
 +
 [source,shell]
 ....
 OK set kern.geom.raid.enable=0
 OK boot
 ....
-+ 
++
 The system will boot with man:graid[8] disabled.
 . Back up all data on the affected drive.
 . As a workaround, man:graid[8] array detection can be disabled by adding
 +
 [.programlisting]
 ....
 kern.geom.raid.enable=0
 ....
-+ 
++
 to [.filename]#/boot/loader.conf#.
-+ 
++
 To permanently remove the man:graid[8] metadata from the affected drive, boot a FreeBSD installation CD-ROM or memory stick, and select `Shell`.
 Use `status` to find the name of the array, typically `raid/r0`:
 +
 [source,shell]
 ....
 # graid status
    Name   Status  Components
 raid/r0  OPTIMAL  ada0 (ACTIVE (ACTIVE))
                   ada1 (ACTIVE (ACTIVE))
 ....
-+ 
++
 Delete the volume by name:
 +
 [source,shell]
 ....
 # graid delete raid/r0
 ....
-+ 
++
 If there is more than one volume shown, repeat the process for each volume.
 After the last array has been deleted, the volume will be destroyed.
-+ 
++
 Reboot and verify data, restoring from backup if necessary.
 After the metadata has been removed, the `kern.geom.raid.enable=0` entry in [.filename]#/boot/loader.conf# can also be removed.
 
 [[geom-ggate]]
 == GEOM Gate Network
 
 GEOM provides a simple mechanism for providing remote access to devices such as disks, CDs, and file systems through the use of the GEOM Gate network daemon, ggated.
 The system with the device runs the server daemon which handles requests made by clients using ggatec.
 The devices should not contain any sensitive data as the connection between the client and the server is not encrypted.
 
 Similar to NFS, which is discussed in crossref:network-servers[network-nfs,"Network File System (NFS)"], ggated is configured using an exports file.
 This file specifies which systems are permitted to access the exported resources and what level of access they are offered.
 For example, to give the client `192.168.1.5` read and write access to the fourth slice on the first SCSI disk, create [.filename]#/etc/gg.exports# with this line:
 
 [.programlisting]
 ....
 192.168.1.5 RW /dev/da0s4d
 ....
 
 Before exporting the device, ensure it is not currently mounted.
 Then, start ggated:
 
 [source,shell]
 ....
 # ggated
 ....
 
 Several options are available for specifying an alternate listening port or changing the default location of the exports file.
 Refer to man:ggated[8] for details.
 
 To access the exported device on the client machine, first use `ggatec` to specify the IP address of the server and the device name of the exported device.
 If successful, this command will display a `ggate` device name to mount.
 Mount that specified device name on a free mount point.
 This example connects to the [.filename]#/dev/da0s4d# partition on `192.168.1.1`, then mounts [.filename]#/dev/ggate0# on [.filename]#/mnt#:
 
 [source,shell]
 ....
 # ggatec create -o rw 192.168.1.1 /dev/da0s4d
 ggate0
 # mount /dev/ggate0 /mnt
 ....
 
 The device on the server may now be accessed through [.filename]#/mnt# on the client.
 For more details about `ggatec` and a few usage examples, refer to man:ggatec[8].
 
 [NOTE]
 ====
 The mount will fail if the device is currently mounted on either the server or any other client on the network.
 If simultaneous access is needed to network resources, use NFS instead.
 ====
 
 When the device is no longer needed, unmount it with `umount` so that the resource is available to other clients.
 
 [[geom-glabel]]
 == Labeling Disk Devices
 
 During system initialization, the FreeBSD kernel creates device nodes as devices are found.
 This method of probing for devices raises some issues.
 For instance, what if a new disk device is added via USB? It is likely that a flash device may be handed the device name of [.filename]#da0# and the original [.filename]#da0# shifted to [.filename]#da1#.
 This will cause issues mounting file systems if they are listed in [.filename]#/etc/fstab# which may also prevent the system from booting.
 
 One solution is to chain SCSI devices in order so a new device added to the SCSI card will be issued unused device numbers.
 But what about USB devices which may replace the primary SCSI disk? This happens because USB devices are usually probed before the SCSI card.
 One solution is to only insert these devices after the system has been booted.
 Another method is to use only a single ATA drive and never list the SCSI devices in [.filename]#/etc/fstab#.
 
 A better solution is to use `glabel` to label the disk devices and use the labels in [.filename]#/etc/fstab#.
 Since `glabel` stores the label in the last sector of a given provider, the label will remain persistent across reboots.
 By using this label as a device, the file-system may always be mounted regardless of what device node it is accessed through.
 
 [NOTE]
 ====
 `glabel` can create both transient and permanent labels. Only permanent labels are consistent across reboots.
 Refer to man:glabel[8] for more information on the differences between labels.
 ====
 
 === Label Types and Examples
 
 Permanent labels can be a generic or a file system label.
 Permanent file system labels can be created with man:tunefs[8] or man:newfs[8].
 These types of labels are created in a sub-directory of [.filename]#/dev#, and will be named according to the file system type.
 For example, UFS2 file system labels will be created in [.filename]#/dev/ufs#.
 Generic permanent labels can be created with `glabel label`.
 These are not file system specific and will be created in [.filename]#/dev/label#.
 
 Temporary labels are destroyed at the next reboot.
 These labels are created in [.filename]#/dev/label# and are suited to experimentation.
 A temporary label can be created using `glabel create`.
 
 To create a permanent label for a UFS2 file system without destroying any data, issue the following command:
 
 [source,shell]
 ....
 # tunefs -L home /dev/da3
 ....
 
 A label should now exist in [.filename]#/dev/ufs# which may be added to [.filename]#/etc/fstab#:
 
 [.programlisting]
 ....
 /dev/ufs/home		/home            ufs     rw              2      2
 ....
 
 [NOTE]
 ====
 The file system must not be mounted while attempting to run `tunefs`.
 ====
 
 Now the file system may be mounted:
 
 [source,shell]
 ....
 # mount /home
 ....
 
 From this point on, so long as the [.filename]#geom_label.ko# kernel module is loaded at boot with [.filename]#/boot/loader.conf# or the `GEOM_LABEL` kernel option is present, the device node may change without any ill effect on the system.
 
 File systems may also be created with a default label by using the `-L` flag with `newfs`.
 Refer to man:newfs[8] for more information.
 
 The following command can be used to destroy the label:
 
 [source,shell]
 ....
 # glabel destroy home
 ....
 
 The following example shows how to label the partitions of a boot disk.
 
 .Labeling Partitions on the Boot Disk
 [example]
 ====
 By permanently labeling the partitions on the boot disk, the system should be able to continue to boot normally, even if the disk is moved to another controller or transferred to a different system.
 For this example, it is assumed that a single ATA disk is used, which is currently recognized by the system as [.filename]#ad0#.
 It is also assumed that the standard FreeBSD partition scheme is used, with [.filename]#/#, [.filename]#/var#, [.filename]#/usr# and [.filename]#/tmp#, as well as a swap partition.
 
 Reboot the system, and at the man:loader[8] prompt, press kbd:[4] to boot into single user mode.
 Then enter the following commands:
 
 [source,shell]
 ....
 # glabel label rootfs /dev/ad0s1a
 GEOM_LABEL: Label for provider /dev/ad0s1a is label/rootfs
 # glabel label var /dev/ad0s1d
 GEOM_LABEL: Label for provider /dev/ad0s1d is label/var
 # glabel label usr /dev/ad0s1f
 GEOM_LABEL: Label for provider /dev/ad0s1f is label/usr
 # glabel label tmp /dev/ad0s1e
 GEOM_LABEL: Label for provider /dev/ad0s1e is label/tmp
 # glabel label swap /dev/ad0s1b
 GEOM_LABEL: Label for provider /dev/ad0s1b is label/swap
 # exit
 ....
 
 The system will continue with multi-user boot.
 After the boot completes, edit [.filename]#/etc/fstab# and replace the conventional device names, with their respective labels.
 The final [.filename]#/etc/fstab# will look like this:
 
 [.programlisting]
 ....
 # Device                Mountpoint      FStype  Options         Dump    Pass#
 /dev/label/swap         none            swap    sw              0       0
 /dev/label/rootfs       /               ufs     rw              1       1
 /dev/label/tmp          /tmp            ufs     rw              2       2
 /dev/label/usr          /usr            ufs     rw              2       2
 /dev/label/var          /var            ufs     rw              2       2
 ....
 
 The system can now be rebooted.
 If everything went well, it will come up normally and `mount` will show:
 
 [source,shell]
 ....
 # mount
 /dev/label/rootfs on / (ufs, local)
 devfs on /dev (devfs, local)
 /dev/label/tmp on /tmp (ufs, local, soft-updates)
 /dev/label/usr on /usr (ufs, local, soft-updates)
 /dev/label/var on /var (ufs, local, soft-updates)
 ....
 
 ====
 
 The man:glabel[8] class supports a label type for UFS file systems, based on the unique file system id, `ufsid`.
 These labels may be found in [.filename]#/dev/ufsid# and are created automatically during system startup.
 It is possible to use `ufsid` labels to mount partitions using [.filename]#/etc/fstab#.
 Use `glabel status` to receive a list of file systems and their corresponding `ufsid` labels:
 
 [source,shell]
 ....
 % glabel status
                   Name  Status  Components
 ufsid/486b6fc38d330916     N/A  ad4s1d
 ufsid/486b6fc16926168e     N/A  ad4s1f
 ....
 
 In the above example, [.filename]#ad4s1d# represents [.filename]#/var#, while [.filename]#ad4s1f# represents [.filename]#/usr#.
 Using the `ufsid` values shown, these partitions may now be mounted with the following entries in [.filename]#/etc/fstab#:
 
 [.programlisting]
 ....
 /dev/ufsid/486b6fc38d330916        /var        ufs        rw        2      2
 /dev/ufsid/486b6fc16926168e        /usr        ufs        rw        2      2
 ....
 
 Any partitions with `ufsid` labels can be mounted in this way, eliminating the need to manually create permanent labels, while still enjoying the benefits of device name independent mounting.
 
 [[geom-gjournal]]
 == UFS Journaling Through GEOM
 
 Support for journals on UFS file systems is available on FreeBSD.
 The implementation is provided through the GEOM subsystem and is configured using `gjournal`.
 Unlike other file system journaling implementations, the `gjournal` method is block based and not implemented as part of the file system.
 It is a GEOM extension.
 
 Journaling stores a log of file system transactions, such as changes that make up a complete disk write operation, before meta-data and file writes are committed to the disk.
 This transaction log can later be replayed to redo file system transactions, preventing file system inconsistencies.
 
 This method provides another mechanism to protect against data loss and inconsistencies of the file system.
 Unlike Soft Updates, which tracks and enforces meta-data updates, and snapshots, which create an image of the file system, a log is stored in disk space specifically for this task.
 For better performance, the journal may be stored on another disk.
 In this configuration, the journal provider or storage device should be listed after the device to enable journaling on.
 
 The [.filename]#GENERIC# kernel provides support for `gjournal`.
 To automatically load the [.filename]#geom_journal.ko# kernel module at boot time, add the following line to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 geom_journal_load="YES"
 ....
 
 If a custom kernel is used, ensure the following line is in the kernel configuration file:
 
 [.programlisting]
 ....
 options	GEOM_JOURNAL
 ....
 
 Once the module is loaded, a journal can be created on a new file system using the following steps.
 In this example, [.filename]#da4# is a new SCSI disk:
 
 [source,shell]
 ....
 # gjournal load
 # gjournal label /dev/da4
 ....
 
 This will load the module and create a [.filename]#/dev/da4.journal# device node on [.filename]#/dev/da4#.
 
 A UFS file system may now be created on the journaled device, then mounted on an existing mount point:
 
 [source,shell]
 ....
 # newfs -O 2 -J /dev/da4.journal
 # mount /dev/da4.journal /mnt
 ....
 
 [NOTE]
 ====
 In the case of several slices, a journal will be created for each individual slice.
 For instance, if [.filename]#ad4s1# and [.filename]#ad4s2# are both slices, then `gjournal` will create [.filename]#ad4s1.journal# and [.filename]#ad4s2.journal#.
 ====
 
 Journaling may also be enabled on current file systems by using `tunefs`.
 However, _always_ make a backup before attempting to alter an existing file system.
 In most cases, `gjournal` will fail if it is unable to create the journal, but this does not protect against data loss incurred as a result of misusing `tunefs`. 
 Refer to man:gjournal[8] and man:tunefs[8] for more information about these commands.
 
 It is possible to journal the boot disk of a FreeBSD system.
 Refer to the article link:{gjournal-desktop}[Implementing UFS Journaling on a Desktop PC] for detailed instructions.
diff --git a/documentation/content/en/books/handbook/jails/_index.adoc b/documentation/content/en/books/handbook/jails/_index.adoc
index 8c8eaa83e8..d278555fea 100644
--- a/documentation/content/en/books/handbook/jails/_index.adoc
+++ b/documentation/content/en/books/handbook/jails/_index.adoc
@@ -1,1226 +1,1226 @@
 ---
 title: Chapter 15. Jails
 part: Part III. System Administration
 prev: books/handbook/security
 next: books/handbook/mac
 description: Jails improve on the concept of the traditional chroot environment in several ways
 tags: ["jails", "creating", "managing", "updating", "ezjail"]
 ---
 
 [[jails]]
 = Jails
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 15
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/jails/
 endif::[]
 
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 :imagesdir: ../../../../static/images/books/handbook/jails/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/jails/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[jails-synopsis]]
 == Synopsis
 
 Since system administration is a difficult task, many tools have been developed to make life easier for the administrator.
 These tools often enhance the way systems are installed, configured, and maintained.
 One of the tools which can be used to enhance the security of a FreeBSD system is _jails_.
 Jails have been available since FreeBSD 4.X and continue to be enhanced in their usefulness, performance, reliability, and security.
 
 Jails build upon the man:chroot[2] concept, which is used to change the root directory of a set of processes.
 This creates a safe environment, separate from the rest of the system.
 Processes created in the chrooted environment can not access files or resources outside of it.
 For that reason, compromising a service running in a chrooted environment should not allow the attacker to compromise the entire system.
 However, a chroot has several limitations.
 It is suited to easy tasks which do not require much flexibility or complex, advanced features.
 Over time, many ways have been found to escape from a chrooted environment, making it a less than ideal solution for securing services.
 
 Jails improve on the concept of the traditional chroot environment in several ways.
 In a traditional chroot environment, processes are only limited in the part of the file system they can access.
 The rest of the system resources, system users, running processes, and the networking subsystem are shared by the chrooted processes and the processes of the host system.
 Jails expand this model by virtualizing access to the file system, the set of users, and the networking subsystem.
 More fine-grained controls are available for tuning the access of a jailed environment.
 Jails can be considered as a type of operating system-level virtualization.
 
 A jail is characterized by four elements:
 
 * A directory subtree: the starting point from which a jail is entered. Once inside the jail, a process is not permitted to escape outside of this subtree.
 * A hostname: which will be used by the jail.
 * An IP address: which is assigned to the jail. The IP address of a jail is often an alias address for an existing network interface.
 * A command: the path name of an executable to run inside the jail. The path is relative to the root directory of the jail environment.
 
 Jails have their own set of users and their own `root` account which are limited to the jail environment.
 The `root` account of a jail is not allowed to perform operations to the system outside of the associated jail environment.
 
 This chapter provides an overview of the terminology and commands for managing FreeBSD jails.
 Jails are a powerful tool for both system administrators, and advanced users.
 
 After reading this chapter, you will know:
 
 * What a jail is and what purpose it may serve in FreeBSD installations.
 * How to build, start, and stop a jail.
 * The basics of jail administration, both from inside and outside the jail.
 
 [IMPORTANT]
 ====
 Jails are a powerful tool, but they are not a security panacea.
 While it is not possible for a jailed process to break out on its own, there are several ways in which an unprivileged user outside the jail can cooperate with a privileged user inside the jail to obtain elevated privileges in the host environment.
 
 Most of these attacks can be mitigated by ensuring that the jail root is not accessible to unprivileged users in the host environment.
 As a general rule, untrusted users with privileged access to a jail should not be given access to the host environment.
 ====
 
 [[jails-terms]]
 == Terms Related to Jails
 
 To facilitate better understanding of parts of the FreeBSD system related to jails, their internals and the way they interact with the rest of FreeBSD, the following terms are used further in this chapter:
 
 man:chroot[8] (command)::
 Utility, which uses man:chroot[2] FreeBSD system call to change the root directory of a process and all its descendants.
 
 man:chroot[2] (environment)::
 The environment of processes running in a "chroot".
 This includes resources such as the part of the file system which is visible, user and group IDs which are available, network interfaces and other IPC mechanisms, etc.
 
 man:jail[8] (command)::
 The system administration utility which allows launching of processes within a jail environment.
 
 host (system, process, user, etc.)::
 The controlling system of a jail environment.
 The host system has access to all the hardware resources available, and can control processes both outside of and inside a jail environment.
 One of the important differences of the host system from a jail is that the limitations which apply to superuser processes inside a jail are not enforced for processes of the host system.
 
 hosted (system, process, user, etc.)::
 A process, user or other entity, whose access to resources is restricted by a FreeBSD jail.
 
 [[jails-build]]
 == Creating and Controlling Jails
 
 Some administrators divide jails into the following two types: "complete" jails, which resemble a real FreeBSD system, and "service" jails, dedicated to one application or service, possibly running with privileges.
 This is only a conceptual division and the process of building a jail is not affected by it.
 When creating a "complete" jail there are two options for the source of the userland: use prebuilt binaries (such as those supplied on an install media) or build from source.
 
 === Installing a Jail
 
 [[jails-install-internet]]
 ==== To install a Jail from the Internet
 
 The man:bsdinstall[8] tool can be used to fetch and install the binaries needed for a jail.
 This will walk through the picking of a mirror, which distributions will be installed into the destination directory, and some basic configuration of the jail:
 
 [source,shell]
 ....
 # bsdinstall jail /here/is/the/jail
 ....
 
 Once the command is complete, the next step is configuring the host to run the jail.
 
 [[jails-install-iso]]
 ==== To install a Jail from an ISO
 
 To install the userland from installation media, first create the root directory for the jail.
 This can be done by setting the `DESTDIR` variable to the proper location.
 
 Start a shell and define `DESTDIR`:
 
 [source,shell]
 ....
 # sh
 # export DESTDIR=/here/is/the/jail
 ....
 
 Mount the install media as covered in man:mdconfig[8] when using the install ISO:
 
 [source,shell]
 ....
 # mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
 # cd /mnt/usr/freebsd-dist/
 ....
 
 Extract the binaries from the tarballs on the install media into the declared destination.
 Minimally, only the base set needs to be extracted, but a complete install can be performed when preferred.
 
 To install just the base system:
 
 [source,shell]
 ....
 # tar -xf base.txz -C $DESTDIR
 ....
 
 To install everything except the kernel:
 
 [source,shell]
 ....
 # for set in base ports; do tar -xf $set.txz -C $DESTDIR ; done
 ....
 
 [[jails-install-source]]
 ==== To build and install a Jail from source
 
 The man:jail[8] manual page explains the procedure for building a jail:
 
 [source,shell]
 ....
 # setenv D /here/is/the/jail
 # mkdir -p $D      <.>
 # cd /usr/src
 # make buildworld  <.>
 # make installworld DESTDIR=$D  <.>
 # make distribution DESTDIR=$D  <.>
 # mount -t devfs devfs $D/dev   <.>
 ....
 
 <.> Selecting a location for a jail is the best starting point. This is where the jail will physically reside within the file system of the jail's host. A good choice can be [.filename]#/usr/jail/jailname#, where _jailname_ is the hostname identifying the jail. Usually, [.filename]#/usr/# has enough space for the jail file system, which for "complete" jails is, essentially, a replication of every file present in a default installation of the FreeBSD base system.
 
 <.> If you have already rebuilt your userland using `make world` or `make buildworld`, you can skip this step and install your existing userland into the new jail.
 
 <.> This command will populate the directory subtree chosen as jail's physical location on the file system with the necessary binaries, libraries, manual pages and so on.
 <.> The `distribution` target for make installs every needed configuration file. In simple words, it installs every installable file of [.filename]#/usr/src/etc/# to the [.filename]#/etc# directory of the jail environment: [.filename]#$D/etc/#.
 
 <.> Mounting the man:devfs[8] file system inside a jail is not required. On the other hand, any, or almost any application requires access to at least one device, depending on the purpose of the given application. It is very important to control access to devices from inside a jail, as improper settings could permit an attacker to do nasty things in the jail. Control over man:devfs[8] is managed through rulesets which are described in the man:devfs[8] and man:devfs.conf[5] manual pages.
 
 === Configuring the Host
 
 Once a jail is installed, it can be started by using the man:jail[8] utility.
 The man:jail[8] utility takes four mandatory arguments which are described in the <<jails-synopsis>>.
 Other arguments may be specified too, e.g., to run the jailed process with the credentials of a specific user.
 The `_command_` argument depends on the type of the jail; for a _virtual system_, [.filename]#/etc/rc# is a good choice, since it will replicate the startup sequence of a real FreeBSD system.
 For a _service_ jail, it depends on the service or application that will run within the jail.
 
 Jails are often started at boot time and the FreeBSD [.filename]#rc# mechanism provides an easy way to do this.
 
 [.procedure]
 * Configure jail parameters in [.filename]#jail.conf#:
 +
 [.programlisting]
 ....
 www {
     host.hostname = www.example.org;           # Hostname
     ip4.addr = 192.168.0.10;                   # IP address of the jail
     path = "/usr/jail/www";                    # Path to the jail
     devfs_ruleset = "www_ruleset";             # devfs ruleset
     mount.devfs;                               # Mount devfs inside the jail
     exec.start = "/bin/sh /etc/rc";            # Start command
     exec.stop = "/bin/sh /etc/rc.shutdown";    # Stop command
 }
 ....
 
-+ 
++
 Configure jails to start at boot time in [.filename]#rc.conf#:
 +
 [.programlisting]
 ....
 jail_enable="YES"   # Set to NO to disable starting of any jails
 ....
-+ 
++
 The default startup of jails configured in man:jail.conf[5], will run the [.filename]#/etc/rc# script of the jail, which assumes the jail is a complete virtual system.
 For service jails, the default startup command of the jail should be changed, by setting the `exec.start` option appropriately.
 +
 [NOTE]
 ====
 For a full list of available options, please see the man:jail.conf[5] manual page.
 ====
 
 man:service[8] can be used to start or stop a jail by hand, if an entry for it exists in [.filename]#jail.conf#:
 
 [source,shell]
 ....
 # service jail start www
 # service jail stop www
 ....
 
 Jails can be shut down with man:jexec[8].
 Use man:jls[8] to identify the jail's `JID`, then use man:jexec[8] to run the shutdown script in that jail.
 
 [source,shell]
 ....
 # jls
    JID  IP Address      Hostname                      Path
      3  192.168.0.10    www                           /usr/jail/www
 # jexec 3 /etc/rc.shutdown
 ....
 
 More information about this can be found in the man:jail[8] manual page.
 
 [[jails-tuning]]
 == Fine Tuning and Administration
 
 There are several options which can be set for any jail, and various ways of combining a host FreeBSD system with jails, to produce higher level applications.
 This section presents:
 
 * Some of the options available for tuning the behavior and security restrictions implemented by a jail installation.
 * Some of the high-level applications for jail management, which are available through the FreeBSD Ports Collection, and can be used to implement overall jail-based solutions.
 
 [[jails-tuning-utilities]]
 === System Tools for Jail Tuning in FreeBSD
 
 Fine tuning of a jail's configuration is mostly done by setting man:sysctl[8] variables.
 A special subtree of sysctl exists as a basis for organizing all the relevant options: the `security.jail.*` hierarchy of FreeBSD kernel options.
 Here is a list of the main jail-related sysctls, complete with their default value.
 Names should be self-explanatory, but for more information about them, please refer to the man:jail[8] and man:sysctl[8] manual pages.
 
 * `security.jail.set_hostname_allowed: 1`
 * `security.jail.socket_unixiproute_only: 1`
 * `security.jail.sysvipc_allowed: 0`
 * `security.jail.enforce_statfs: 2`
 * `security.jail.allow_raw_sockets: 0`
 * `security.jail.chflags_allowed: 0`
 * `security.jail.jailed: 0`
 
 These variables can be used by the system administrator of the _host system_ to add or remove some of the limitations imposed by default on the `root` user.
 Note that there are some limitations which cannot be removed.
 The `root` user is not allowed to mount or unmount file systems from within a man:jail[8].
 The `root` inside a jail may not load or unload man:devfs[8] rulesets, set firewall rules, or do many other administrative tasks which require modifications of in-kernel data, such as setting the `securelevel` of the kernel.
 
 The base system of FreeBSD contains a basic set of tools for viewing information about the active jails, and attaching to a jail to run administrative commands.
 The man:jls[8] and man:jexec[8] commands are part of the base FreeBSD system, and can be used to perform the following simple tasks:
 
 * Print a list of active jails and their corresponding jail identifier (JID), IP address, hostname and path.
 * Attach to a running jail, from its host system, and run a command inside the jail or perform administrative tasks inside the jail itself. This is especially useful when the `root` user wants to cleanly shut down a jail. The man:jexec[8] utility can also be used to start a shell in a jail to do administration in it; for example:
 +
 [source,shell]
 ....
 # jexec 1 tcsh
 ....
 
 [[jails-tuning-admintools]]
 === High-Level Administrative Tools in the FreeBSD Ports Collection
 
 Among the many third-party utilities for jail administration, one of the most complete and useful is package:sysutils/ezjail[].
 It is a set of scripts that contribute to man:jail[8] management.
 Please refer to <<jails-ezjail,the handbook section on ezjail>> for more information.
 
 [[jails-updating]]
 === Keeping Jails Patched and up to Date
 
 Jails should be kept up to date from the host operating system as attempting to patch userland from within the jail may likely fail as the default behavior in FreeBSD is to disallow the use of man:chflags[1] in a jail which prevents the replacement of some files.
 It is possible to change this behavior but it is recommended to use man:freebsd-update[8] to maintain jails instead.
 Use `-b` to specify the path of the jail to be updated.
 
 To update the jail to the latest patch release of the version of FreeBSD it is already running, then execute the following commands on the host:
 
 [source,shell]
 ....
 # freebsd-update -b /here/is/the/jail fetch
 # freebsd-update -b /here/is/the/jail install
 ....
 
 To upgrade the jail to a new major or minor version, first upgrade the host system as described in crossref:cutting-edge[freebsdupdate-upgrade,“Performing Major and Minor Version Upgrades”].
 Once the host has been upgraded and rebooted, the jail can then be upgraded.
 For example to upgrade from 12.0-RELEASE to 12.1-RELEASE, on the host run:
 
 [source,shell]
 ....
 # freebsd-update -b /here/is/the/jail --currently-running 12.0-RELEASE -r 12.1-RELEASE upgrade
 # freebsd-update -b /here/is/the/jail install
 # service jail restart myjail
 # freebsd-update -b /here/is/the/jail install
 ....
 
 Then, if it was a major version upgrade, reinstall all installed packages and restart the jail again.
 This is required because the ABI version changes when upgrading between major versions of FreeBSD.
 From the host:
 
 [source,shell]
 ....
 # pkg -j myjail upgrade -f
 # service jail restart myjail
 ....
 
 [[jails-application]]
 == Updating Multiple Jails
 
 The management of multiple jails can become problematic because every jail has to be rebuilt from scratch whenever it is upgraded.
 This can be time consuming and tedious if a lot of jails are created and manually updated.
 
 This section demonstrates one method to resolve this issue by safely sharing as much as is possible between jails using read-only man:mount_nullfs[8] mounts, so that updating is simpler.
 This makes it more attractive to put single services, such as HTTP, DNS, and SMTP, into individual jails.
 Additionally, it provides a simple way to add, remove, and upgrade jails.
 
 [NOTE]
 ====
 Simpler solutions exist, such as ezjail, which provides an easier method of administering FreeBSD jails but is less versatile than this setup.
 ezjail is covered in more detail in <<jails-ezjail>>.
 ====
 
 The goals of the setup described in this section are:
 
 * Create a simple and easy to understand jail structure that does not require running a full installworld on each and every jail.
 * Make it easy to add new jails or remove existing ones.
 * Make it easy to update or upgrade existing jails.
 * Make it possible to run a customized FreeBSD branch.
 * Be paranoid about security, reducing as much as possible the possibility of compromise.
 * Save space and inodes, as much as possible.
 
 This design relies on a single, read-only master template which is mounted into each jail and one read-write device per jail.
 A device can be a separate physical disc, a partition, or a vnode backed memory device.
 This example uses read-write nullfs mounts.
 
 The file system layout is as follows:
 
 * The jails are based under the [.filename]#/home# partition.
 * Each jail will be mounted under the [.filename]#/home/j# directory.
 * The template for each jail and the read-only partition for all of the jails is [.filename]#/home/j/mroot#.
 * A blank directory will be created for each jail under the [.filename]#/home/j# directory.
 * Each jail will have a [.filename]#/s# directory that will be linked to the read-write portion of the system.
 * Each jail will have its own read-write system that is based upon [.filename]#/home/j/skel#.
 * The read-write portion of each jail will be created in [.filename]#/home/js#.
 
 [[jails-service-jails-template]]
 === Creating the Template
 
 This section describes the steps needed to create the master template.
 
 It is recommended to first update the host FreeBSD system to the latest -RELEASE branch using the instructions in crossref:cutting-edge[makeworld,“Updating FreeBSD from Source”].
 Additionally, this template uses the package:sysutils/cpdup[] package or port and portsnap will be used to download the FreeBSD Ports Collection.
 
 [.procedure]
 . First, create a directory structure for the read-only file system which will contain the FreeBSD binaries for the jails. Then, change directory to the FreeBSD source tree and install the read-only file system to the jail template:
 +
 [source,shell]
 ....
 # mkdir /home/j /home/j/mroot
 # cd /usr/src
 # make installworld DESTDIR=/home/j/mroot
 ....
 
 . Next, prepare a FreeBSD Ports Collection for the jails as well as a FreeBSD source tree, which is required for mergemaster:
 +
 [source,shell]
 ....
 # cd /home/j/mroot
 # mkdir usr/ports
 # portsnap -p /home/j/mroot/usr/ports fetch extract
 # cpdup /usr/src /home/j/mroot/usr/src
 ....
 
 . Create a skeleton for the read-write portion of the system:
 +
 [source,shell]
 ....
 # mkdir /home/j/skel /home/j/skel/home /home/j/skel/usr-X11R6 /home/j/skel/distfiles
 # mv etc /home/j/skel
 # mv usr/local /home/j/skel/usr-local
 # mv tmp /home/j/skel
 # mv var /home/j/skel
 # mv root /home/j/skel
 ....
 
 . Use mergemaster to install missing configuration files. Then, remove the extra directories that mergemaster creates:
 +
 [source,shell]
 ....
 # mergemaster -t /home/j/skel/var/tmp/temproot -D /home/j/skel -i
 # cd /home/j/skel
 # rm -R bin boot lib libexec mnt proc rescue sbin sys usr dev
 ....
 
 . Now, symlink the read-write file system to the read-only file system. Ensure that the symlinks are created in the correct [.filename]#s/# locations as the creation of directories in the wrong locations will cause the installation to fail.
 +
 [source,shell]
 ....
 # cd /home/j/mroot
 # mkdir s
 # ln -s s/etc etc
 # ln -s s/home home
 # ln -s s/root root
 # ln -s ../s/usr-local usr/local
 # ln -s ../s/usr-X11R6 usr/X11R6
 # ln -s ../../s/distfiles usr/ports/distfiles
 # ln -s s/tmp tmp
 # ln -s s/var var
 ....
 
 . As a last step, create a generic [.filename]#/home/j/skel/etc/make.conf# containing this line:
 +
 [.programlisting]
 ....
 WRKDIRPREFIX?=  /s/portbuild
 ....
-+ 
++
 This makes it possible to compile FreeBSD ports inside each jail.
 Remember that the ports directory is part of the read-only system.
 The custom path for `WRKDIRPREFIX` allows builds to be done in the read-write portion of every jail.
 
 [[jails-service-jails-creating]]
 === Creating Jails
 
 The jail template can now be used to setup and configure the jails in [.filename]#/etc/rc.conf#.
 This example demonstrates the creation of 3 jails: `NS`, `MAIL` and `WWW`.
 
 [.procedure]
 . Add the following lines to [.filename]#/etc/fstab#, so that the read-only template for the jails and the read-write space will be available in the respective jails:
 +
 [.programlisting]
 ....
 /home/j/mroot   /home/j/ns     nullfs  ro  0   0
 /home/j/mroot   /home/j/mail   nullfs  ro  0   0
 /home/j/mroot   /home/j/www    nullfs  ro  0   0
 /home/js/ns     /home/j/ns/s   nullfs  rw  0   0
 /home/js/mail   /home/j/mail/s nullfs  rw  0   0
 /home/js/www    /home/j/www/s  nullfs  rw  0   0
 ....
-+ 
++
 To prevent fsck from checking nullfs mounts during boot and dump from backing up the read-only nullfs mounts of the jails, the last two columns are both set to `0`.
 . Configure the jails in [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 jail_enable="YES"
 jail_set_hostname_allow="NO"
 jail_list="ns mail www"
 jail_ns_hostname="ns.example.org"
 jail_ns_ip="192.168.3.17"
 jail_ns_rootdir="/usr/home/j/ns"
 jail_ns_devfs_enable="YES"
 jail_mail_hostname="mail.example.org"
 jail_mail_ip="192.168.3.18"
 jail_mail_rootdir="/usr/home/j/mail"
 jail_mail_devfs_enable="YES"
 jail_www_hostname="www.example.org"
 jail_www_ip="62.123.43.14"
 jail_www_rootdir="/usr/home/j/www"
 jail_www_devfs_enable="YES"
 ....
-+ 
++
 The `jail__name__rootdir` variable is set to [.filename]#/usr/home# instead of [.filename]#/home# because the physical path of [.filename]#/home# on a default FreeBSD installation is [.filename]#/usr/home#.
 The `jail__name__rootdir` variable must _not_ be set to a path which includes a symbolic link, otherwise the jails will refuse to start.
 . Create the required mount points for the read-only file system of each jail:
 +
 [source,shell]
 ....
 # mkdir /home/j/ns /home/j/mail /home/j/www
 ....
 
 . Install the read-write template into each jail using package:sysutils/cpdup[]:
 +
 [source,shell]
 ....
 # mkdir /home/js
 # cpdup /home/j/skel /home/js/ns
 # cpdup /home/j/skel /home/js/mail
 # cpdup /home/j/skel /home/js/www
 ....
 
 . In this phase, the jails are built and prepared to run. First, mount the required file systems for each jail, and then start them:
 +
 [source,shell]
 ....
 # mount -a
 # service jail start
 ....
 
 The jails should be running now.
 To check if they have started correctly, use `jls`.
 Its output should be similar to the following:
 
 [source,shell]
 ....
 # jls
    JID  IP Address      Hostname                      Path
      3  192.168.3.17    ns.example.org                /home/j/ns
      2  192.168.3.18    mail.example.org              /home/j/mail
      1  62.123.43.14    www.example.org               /home/j/www
 ....
 
 At this point, it should be possible to log onto each jail, add new users, or configure daemons.
 The `JID` column indicates the jail identification number of each running jail.
 Use the following command to perform administrative tasks in the jail whose JID is `3`:
 
 [source,shell]
 ....
 # jexec 3 tcsh
 ....
 
 [[jails-service-jails-upgrading]]
 === Upgrading
 
 The design of this setup provides an easy way to upgrade existing jails while minimizing their downtime.
 Also, it provides a way to roll back to the older version should a problem occur.
 
 [.procedure]
 . The first step is to upgrade the host system. Then, create a new temporary read-only template in [.filename]#/home/j/mroot2#.
 +
 [source,shell]
 ....
 # mkdir /home/j/mroot2
 # cd /usr/src
 # make installworld DESTDIR=/home/j/mroot2
 # cd /home/j/mroot2
 # cpdup /usr/src usr/src
 # mkdir s
 ....
-+ 
++
 The `installworld` creates a few unnecessary directories, which should be removed:
 +
 [source,shell]
 ....
 # chflags -R 0 var
 # rm -R etc var root usr/local tmp
 ....
 
 . Recreate the read-write symlinks for the master file system:
 +
 [source,shell]
 ....
 # ln -s s/etc etc
 # ln -s s/root root
 # ln -s s/home home
 # ln -s ../s/usr-local usr/local
 # ln -s ../s/usr-X11R6 usr/X11R6
 # ln -s s/tmp tmp
 # ln -s s/var var
 ....
 
 . Next, stop the jails:
 +
 [source,shell]
 ....
 # service jail stop
 ....
 
 . Unmount the original file systems as the read-write systems are attached to the read-only system ([.filename]#/s#):
 +
 [source,shell]
 ....
 # umount /home/j/ns/s
 # umount /home/j/ns
 # umount /home/j/mail/s
 # umount /home/j/mail
 # umount /home/j/www/s
 # umount /home/j/www
 ....
 
 . Move the old read-only file system and replace it with the new one. This will serve as a backup and archive of the old read-only file system should something go wrong. The naming convention used here corresponds to when a new read-only file system has been created. Move the original FreeBSD Ports Collection over to the new file system to save some space and inodes:
 +
 [source,shell]
 ....
 # cd /home/j
 # mv mroot mroot.20060601
 # mv mroot2 mroot
 # mv mroot.20060601/usr/ports mroot/usr
 ....
 
 . At this point the new read-only template is ready, so the only remaining task is to remount the file systems and start the jails:
 +
 [source,shell]
 ....
 # mount -a
 # service jail start
 ....
 
 Use `jls` to check if the jails started correctly.
 Run `mergemaster` in each jail to update the configuration files.
 
 [[jails-ezjail]]
 == Managing Jails with ezjail
 
 Creating and managing multiple jails can quickly become tedious and error-prone.
 Dirk Engling's ezjail automates and greatly simplifies many jail tasks.
 A _basejail_ is created as a template.
 Additional jails use man:mount_nullfs[8] to share many of the basejail directories without using additional disk space.
 Each additional jail takes only a few megabytes of disk space before applications are installed.
 Upgrading the copy of the userland in the basejail automatically upgrades all of the other jails.
 
 Additional benefits and features are described in detail on the ezjail web site, https://erdgeist.org/arts/software/ezjail/[].
 
 [[jails-ezjail-install]]
 === Installing ezjail
 
 Installing ezjail consists of adding a loopback interface for use in jails, installing the port or package, and enabling the service.
 
 [[jails-ezjail-install-procedure]]
 [.procedure]
 . To keep jail loopback traffic off the host's loopback network interface `lo0`, a second loopback interface is created by adding an entry to [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 cloned_interfaces="lo1"
 ....
-+ 
++
 The second loopback interface `lo1` will be created when the system starts.
 It can also be created manually without a restart:
 +
 [source,shell]
 ....
 # service netif cloneup
 Created clone interfaces: lo1.
 ....
-+ 
++
 Jails can be allowed to use aliases of this secondary loopback interface without interfering with the host.
-+ 
++
 Inside a jail, access to the loopback address `127.0.0.1` is redirected to the first IP address assigned to the jail.
 To make the jail loopback correspond with the new `lo1` interface, that interface must be specified first in the list of interfaces and IP addresses given when creating a new jail.
-+ 
++
 Give each jail a unique loopback address in the `127.0.0.0/8` netblock.
 . Install package:sysutils/ezjail[]:
 +
 [source,shell]
 ....
 # cd /usr/ports/sysutils/ezjail
 # make install clean
 ....
 
 . Enable ezjail by adding this line to [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 ezjail_enable="YES"
 ....
 
 . The service will automatically start on system boot. It can be started immediately for the current session:
 +
 [source,shell]
 ....
 # service ezjail start
 ....
 
 [[jails-ezjail-initialsetup]]
 === Initial Setup
 
 With ezjail installed, the basejail directory structure can be created and populated.
 This step is only needed once on the jail host computer.
 
 In both of these examples, `-p` causes the ports tree to be retrieved with man:portsnap[8] into the basejail.
 That single copy of the ports directory will be shared by all the jails.
 Using a separate copy of the ports directory for jails isolates them from the host.
 The ezjailFAQ explains in more detail: http://erdgeist.org/arts/software/ezjail/#FAQ[].
 
 [[jails-ezjail-initialsetup-procedure]]
 [.procedure]
 
 . To Populate the Jail with FreeBSD-RELEASE
-+ 
++
 For a basejail based on the FreeBSD RELEASE matching that of the host computer, use `install`.
 For example, on a host computer running FreeBSD 10-STABLE, the latest RELEASE version of FreeBSD -10 will be installed in the jail):
 +
 [source,shell]
 ....
 # ezjail-admin install -p
 ....
 
 . To Populate the Jail with `installworld`
-+ 
++
 The basejail can be installed from binaries created by `buildworld` on the host with `ezjail-admin update`.
-+ 
++
 In this example, FreeBSD 10-STABLE has been built from source.
 The jail directories are created.
 Then `installworld` is executed, installing the host's [.filename]#/usr/obj# into the basejail.
 +
 [source,shell]
 ....
 # ezjail-admin update -i -p
 ....
-+ 
++
 The host's [.filename]#/usr/src# is used by default.
 A different source directory on the host can be specified with `-s` and a path, or set with `ezjail_sourcetree` in [.filename]#/usr/local/etc/ezjail.conf#.
 
 [TIP]
 ====
 The basejail's ports tree is shared by other jails.
 However, downloaded distfiles are stored in the jail that downloaded them.
 By default, these files are stored in [.filename]#/var/ports/distfiles# within each jail.
 [.filename]#/var/ports# inside each jail is also used as a work directory when building ports.
 ====
 
 [TIP]
 ====
 The FTP protocol is used by default to download packages for the installation of the basejail.
 Firewall or proxy configurations can prevent or interfere with FTP transfers.
 The HTTP protocol works differently and avoids these problems.
 It can be chosen by specifying a full URL for a particular download mirror in [.filename]#/usr/local/etc/ezjail.conf#:
 
 [.programlisting]
 ....
 ezjail_ftphost=http://ftp.FreeBSD.org
 ....
 
 See crossref:mirrors[mirrors-ftp,“FTP Sites”] for a list of sites.
 ====
 
 [[jails-ezjail-create]]
 === Creating and Starting a New Jail
 
 New jails are created with `ezjail-admin create`.
 In these examples, the `lo1` loopback interface is used as described above.
 
 [[jails-ezjail-create-steps]]
 [.procedure]
 .Procedure: Create and Start a New Jail
 . Create the jail, specifying a name and the loopback and network interfaces to use, along with their IP addresses. In this example, the jail is named `dnsjail`.
 +
 [source,shell]
 ....
 # ezjail-admin create dnsjail 'lo1|127.0.1.1,em0|192.168.1.50'
 ....
 +
 [TIP]
 ====
 Most network services run in jails without problems.
 A few network services, most notably man:ping[8], use _raw network sockets_.
 In jails, raw network sockets are disabled by default for security.
 Services that require them will not work.
 
 Occasionally, a jail genuinely needs raw sockets.
 For example, network monitoring applications often use man:ping[8] to check the availability of other computers.
 When raw network sockets are actually needed in a jail, they can be enabled by editing the ezjail configuration file for the individual jail, [.filename]#/usr/local/etc/ezjail/jailname#.
 Modify the `parameters` entry:
 
 [.programlisting]
 ....
 export jail_jailname_parameters="allow.raw_sockets=1"
 ....
 
 Do not enable raw network sockets unless services in the jail actually require them.
 ====
 
 . Start the jail:
 +
 [source,shell]
 ....
 # ezjail-admin start dnsjail
 ....
 
 . Use a console on the jail:
 +
 [source,shell]
 ....
 # ezjail-admin console dnsjail
 ....
 
 The jail is operating and additional configuration can be completed.
 Typical settings added at this point include:
 
 [.procedure]
 . Set the `root` Password
-+ 
++
 Connect to the jail and set the `root` user's password:
 +
 [source,shell]
 ....
 # ezjail-admin console dnsjail
 # passwd
 Changing local password for root
 New Password:
 Retype New Password:
 ....
 
 . Time Zone Configuration
-+ 
++
 The jail's time zone can be set with man:tzsetup[8].
 To avoid spurious error messages, the man:adjkerntz[8] entry in [.filename]#/etc/crontab# can be commented or removed.
 This job attempts to update the computer's hardware clock with time zone changes, but jails are not allowed to access that hardware.
 . DNS Servers
-+ 
++
 Enter domain name server lines in [.filename]#/etc/resolv.conf# so DNS works in the jail.
 . Edit [.filename]#/etc/hosts#
-+ 
++
 Change the address and add the jail name to the `localhost` entries in [.filename]#/etc/hosts#.
 . Configure [.filename]#/etc/rc.conf#
-+ 
++
 Enter configuration settings in [.filename]#/etc/rc.conf#.
 This is much like configuring a full computer.
 The host name and IP address are not set here.
 Those values are already provided by the jail configuration.
 
 With the jail configured, the applications for which the jail was created can be installed.
 
 [TIP]
 ====
 Some ports must be built with special options to be used in a jail.
 For example, both of the network monitoring plugin packages package:net-mgmt/nagios-plugins[] and package:net-mgmt/monitoring-plugins[] have a `JAIL` option which must be enabled for them to work correctly inside a jail.
 ====
 
 [[jails-ezjail-update]]
 === Updating Jails
 
 [[jails-ezjail-update-os]]
 ==== Updating the Operating System
 
 Because the basejail's copy of the userland is shared by the other jails, updating the basejail automatically updates all of the other jails.
 Either source or binary updates can be used.
 
 To build the world from source on the host, then install it in the basejail, use:
 
 [source,shell]
 ....
 # ezjail-admin update -b
 ....
 
 If the world has already been compiled on the host, install it in the basejail with:
 
 [source,shell]
 ....
 # ezjail-admin update -i
 ....
 
 Binary updates use man:freebsd-update[8].
 These updates have the same limitations as if man:freebsd-update[8] were being run directly.
 The most important one is that only -RELEASE versions of FreeBSD are available with this method.
 
 Update the basejail to the latest patched release of the version of FreeBSD on the host.
 For example, updating from RELEASE-p1 to RELEASE-p2.
 
 [source,shell]
 ....
 # ezjail-admin update -u
 ....
 
 To upgrade the basejail to a new version, first upgrade the host system as described in crossref:cutting-edge[freebsdupdate-upgrade,“Performing Major and Minor Version Upgrades”].
 Once the host has been upgraded and rebooted, the basejail can then be upgraded.
 man:freebsd-update[8] has no way of determining which version is currently installed in the basejail, so the original version must be specified.
 Use man:file[1] to determine the original version in the basejail:
 
 [source,shell]
 ....
 # file /usr/jails/basejail/bin/sh
 /usr/jails/basejail/bin/sh: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked (uses shared libs), for FreeBSD 9.3, stripped
 ....
 
 Now use this information to perform the upgrade from `9.3-RELEASE` to the current version of the host system:
 
 [source,shell]
 ....
 # ezjail-admin update -U -s 9.3-RELEASE
 ....
 
 After updating the basejail, man:mergemaster[8] must be run to update each jail's configuration files.
 
 How to use man:mergemaster[8] depends on the purpose and trustworthiness of a jail.
 If a jail's services or users are not trusted, then man:mergemaster[8] should only be run from within that jail:
 
 [[jails-ezjail-update-mergemaster-untrusted]]
 .man:mergemaster[8] on Untrusted Jail
 [example]
 ====
 Delete the link from the jail's [.filename]#/usr/src# into the basejail and create a new [.filename]#/usr/src# in the jail as a mountpoint.
 Mount the host computer's [.filename]#/usr/src# read-only on the jail's new [.filename]#/usr/src# mountpoint:
 
 [source,shell]
 ....
 # rm /usr/jails/jailname/usr/src
 # mkdir /usr/jails/jailname/usr/src
 # mount -t nullfs -o ro /usr/src /usr/jails/jailname/usr/src
 ....
 
 Get a console in the jail:
 
 [source,shell]
 ....
 # ezjail-admin console jailname
 ....
 
 Inside the jail, run `mergemaster`.
 Then exit the jail console:
 
 [source,shell]
 ....
 # cd /usr/src
 # mergemaster -U
 # exit
 ....
 
 Finally, unmount the jail's [.filename]#/usr/src#:
 
 [source,shell]
 ....
 # umount /usr/jails/jailname/usr/src
 ....
 
 ====
 
 [[jails-ezjail-update-mergemaster-trusted]]
 .man:mergemaster[8] on Trusted Jail
 [example]
 ====
 
 If the users and services in a jail are trusted, man:mergemaster[8] can be run from the host:
 
 [source,shell]
 ....
 # mergemaster -U -D /usr/jails/jailname
 ....
 
 ====
 
 [TIP]
 ====
 After a major version update it is recommended by package:sysutils/ezjail[] to make sure your `pkg` is of the correct version.
 Therefore enter:
 
 [source,shell]
 ....
 # pkg-static upgrade -f pkg
 ....
 
 to upgrade or downgrade to the appropriate version.
 ====
 
 [[jails-ezjail-update-ports]]
 ==== Updating Ports
 
 The ports tree in the basejail is shared by the other jails.
 Updating that copy of the ports tree gives the other jails the updated version also.
 
 The basejail ports tree is updated with man:portsnap[8]:
 
 [source,shell]
 ....
 # ezjail-admin update -P
 ....
 
 [[jails-ezjail-control]]
 === Controlling Jails
 
 [[jails-ezjail-control-stop-start]]
 ==== Stopping and Starting Jails
 
 ezjail automatically starts jails when the computer is started.
 Jails can be manually stopped and restarted with `stop` and `start`:
 
 [source,shell]
 ....
 # ezjail-admin stop sambajail
 Stopping jails: sambajail.
 ....
 
 By default, jails are started automatically when the host computer starts.
 Autostarting can be disabled with `config`:
 
 [source,shell]
 ....
 # ezjail-admin config -r norun seldomjail
 ....
 
 This takes effect the next time the host computer is started.
 A jail that is already running will not be stopped.
 
 Enabling autostart is very similar:
 
 [source,shell]
 ....
 # ezjail-admin config -r run oftenjail
 ....
 
 [[jails-ezjail-control-backup]]
 ==== Archiving and Restoring Jails
 
 Use `archive` to create a [.filename]#.tar.gz# archive of a jail.
 The file name is composed from the name of the jail and the current date.
 Archive files are written to the archive directory, [.filename]#/usr/jails/ezjail_archives#.
 A different archive directory can be chosen by setting `ezjail_archivedir` in the configuration file.
 
 The archive file can be copied elsewhere as a backup, or an existing jail can be restored from it with `restore`.
 A new jail can be created from the archive, providing a convenient way to clone existing jails.
 
 Stop and archive a jail named `wwwserver`:
 
 [source,shell]
 ....
 # ezjail-admin stop wwwserver
 Stopping jails: wwwserver.
 # ezjail-admin archive wwwserver
 # ls /usr/jails/ezjail-archives/
 wwwserver-201407271153.13.tar.gz
 ....
 
 Create a new jail named `wwwserver-clone` from the archive created in the previous step.
 Use the [.filename]#em1# interface and assign a new IP address to avoid conflict with the original:
 
 [source,shell]
 ....
 # ezjail-admin create -a /usr/jails/ezjail_archives/wwwserver-201407271153.13.tar.gz wwwserver-clone 'lo1|127.0.3.1,em1|192.168.1.51'
 ....
 
 [[jails-ezjail-example-bind]]
 === Full Example: BIND in a Jail
 
 Putting the BINDDNS server in a jail improves security by isolating it.
 This example creates a simple caching-only name server.
 
 * The jail will be called `dns1`.
 * The jail will use IP address `192.168.1.240` on the host's `re0` interface.
 * The upstream ISP's DNS servers are at `10.0.0.62` and `10.0.0.61`.
 * The basejail has already been created and a ports tree installed as shown in <<jails-ezjail-initialsetup>>.
 
 [[jails-ezjail-example-bind-steps]]
 .Running BIND in a Jail
 [example]
 ====
 
 Create a cloned loopback interface by adding a line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 cloned_interfaces="lo1"
 ....
 
 Immediately create the new loopback interface:
 
 [source,shell]
 ....
 # service netif cloneup
 Created clone interfaces: lo1.
 ....
 
 Create the jail:
 
 [source,shell]
 ....
 # ezjail-admin create dns1 'lo1|127.0.2.1,re0|192.168.1.240'
 ....
 
 Start the jail, connect to a console running on it, and perform some basic configuration:
 
 [source,shell]
 ....
 # ezjail-admin start dns1
 # ezjail-admin console dns1
 # passwd
 Changing local password for root
 New Password:
 Retype New Password:
 # tzsetup
 # sed -i .bak -e '/adjkerntz/ s/^/#/' /etc/crontab
 # sed -i .bak -e 's/127.0.0.1/127.0.2.1/g; s/localhost.my.domain/dns1.my.domain dns1/' /etc/hosts
 ....
 
 Temporarily set the upstream DNS servers in [.filename]#/etc/resolv.conf# so ports can be downloaded:
 
 [.programlisting]
 ....
 nameserver 10.0.0.62
 nameserver 10.0.0.61
 ....
 
 Still using the jail console, install package:dns/bind99[].
 
 [source,shell]
 ....
 # make -C /usr/ports/dns/bind99 install clean
 ....
 
 Configure the name server by editing [.filename]#/usr/local/etc/namedb/named.conf#.
 
 Create an Access Control List (ACL) of addresses and networks that are permitted to send DNS queries to this name server.
 This section is added just before the `options` section already in the file:
 
 [.programlisting]
 ....
 ...
 // or cause huge amounts of useless Internet traffic.
 
 acl "trusted" {
 	192.168.1.0/24;
 	localhost;
 	localnets;
 };
 
 options {
 ...
 ....
 
 Use the jail IP address in the `listen-on` setting to accept DNS queries from other computers on the network:
 
 [.programlisting]
 ....
 	listen-on	{ 192.168.1.240; };
 ....
 
 A simple caching-only DNS name server is created by changing the `forwarders` section.
 The original file contains:
 
 [.programlisting]
 ....
 /*
 	forwarders {
 		127.0.0.1;
 	};
 */
 ....
 
 Uncomment the section by removing the `/\*` and `*/` lines.
 Enter the IP addresses of the upstream DNS servers.
 Immediately after the `forwarders` section, add references to the `trusted` ACL defined earlier:
 
 [.programlisting]
 ....
 	forwarders {
 		10.0.0.62;
 		10.0.0.61;
 	};
 
 	allow-query       { any; };
 	allow-recursion   { trusted; };
 	allow-query-cache { trusted; };
 ....
 
 Enable the service in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 named_enable="YES"
 ....
 
 Start and test the name server:
 
 [source,shell]
 ....
 # service named start
 wrote key file "/usr/local/etc/namedb/rndc.key"
 Starting named.
 # /usr/local/bin/dig @192.168.1.240 freebsd.org
 ....
 
 A response that includes
 
 [source,shell]
 ....
 ;; Got answer;
 ....
 
 shows that the new DNS server is working.
 A long delay followed by a response including
 
 [source,shell]
 ....
 ;; connection timed out; no servers could be reached
 ....
 
 shows a problem.
 Check the configuration settings and make sure any local firewalls allow the new DNS access to the upstream DNS servers.
 
 The new DNS server can use itself for local name resolution, just like other local computers.
 Set the address of the DNS server in the client computer's [.filename]#/etc/resolv.conf#:
 
 [.programlisting]
 ....
 nameserver 192.168.1.240
 ....
 
 A local DHCP server can be configured to provide this address for a local DNS server, providing automatic configuration on DHCP clients.
 ====
diff --git a/documentation/content/en/books/handbook/mail/_index.adoc b/documentation/content/en/books/handbook/mail/_index.adoc
index aede8782f0..03f363da37 100644
--- a/documentation/content/en/books/handbook/mail/_index.adoc
+++ b/documentation/content/en/books/handbook/mail/_index.adoc
@@ -1,1114 +1,1114 @@
 ---
 title: Chapter 29. Electronic Mail
 part: IV. Network Communication
 prev: books/handbook/ppp-and-slip
 next: books/handbook/network-servers
 description: This chapter provides a basic introduction to running a mail server on FreeBSD, as well as an introduction to sending and receiving email using FreeBSD
 tags: ["mail", "sendmail", "MTA", "SMTP", "user agents", "fetchmail", "procmail", "alpine", "mut"]
 ---
 
 [[mail]]
 = Electronic Mail
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 29
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/mail/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/mail/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/mail/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[mail-synopsis]]
 == Synopsis
 
 "Electronic Mail", better known as email, is one of the most widely used forms of communication today.
 This chapter provides a basic introduction to running a mail server on FreeBSD, as well as an introduction to sending and receiving email using FreeBSD
 For more complete coverage of this subject, refer to the books listed in crossref:bibliography[bibliography,Bibliography].
 
 After reading this chapter, you will know:
 
 * Which software components are involved in sending and receiving electronic mail.
 * Where basic Sendmail configuration files are located in FreeBSD.
 * The difference between remote and local mailboxes.
 * How to block spammers from illegally using a mail server as a relay.
 * How to install and configure an alternate Mail Transfer Agent, replacing Sendmail.
 * How to troubleshoot common mail server problems.
 * How to set up the system to send mail only.
 * How to use mail with a dialup connection.
 * How to configure SMTP authentication for added security.
 * How to install and use a Mail User Agent, such as mutt, to send and receive email.
 * How to download mail from a remote POP or IMAP server.
 * How to automatically apply filters and rules to incoming email.
 
 Before reading this chapter, you should:
 
 * Properly set up a network connection (crossref:advanced-networking[advanced-networking,Advanced Networking]).
 * Properly set up the DNS information for a mail host (crossref:network-servers[network-servers,Network Servers]).
 * Know how to install additional third-party software (crossref:ports[ports,Installing Applications: Packages and Ports]).
 
 [[mail-using]]
 == Mail Components
 
 There are five major parts involved in an email exchange: the Mail User Agent (MUA), the Mail Transfer Agent (MTA), a mail host, a remote or local mailbox, and DNS. This section provides an overview of these components.
 
 Mail User Agent (MUA)::
 The Mail User Agent (MUA) is an application which is used to compose, send, and receive emails.
 This application can be a command line program, such as the built-in `mail` utility or a third-party application from the Ports Collection, such as mutt, alpine, or elm.
 Dozens of graphical programs are also available in the Ports Collection, including Claws Mail, Evolution, and Thunderbird.
 Some organizations provide a web mail program which can be accessed through a web browser.
 More information about installing and using a MUA on FreeBSD can be found in <<mail-agents>>.
 
 Mail Transfer Agent (MTA)::
 The Mail Transfer Agent (MTA) is responsible for receiving incoming mail and delivering outgoing mail.
 FreeBSD ships with Sendmail as the default MTA, but it also supports numerous other mail server daemons, including Exim, Postfix, and qmail.
 Sendmail configuration is described in <<sendmail>>.
 If another MTA is installed using the Ports Collection, refer to its post-installation message for FreeBSD-specific configuration details and the application's website for more general configuration instructions.
 
 Mail Host and Mailboxes::
 The mail host is a server that is responsible for delivering and receiving mail for a host or a network.
 The mail host collects all mail sent to the domain and stores it either in the default [.filename]#mbox# or the alternative Maildir format, depending on the configuration.
 Once mail has been stored, it may either be read locally using a MUA or remotely accessed and collected using protocols such as POP or IMAP.
 If mail is read locally, a POP or IMAP server does not need to be installed.
 +
 To access mailboxes remotely, a POP or IMAP server is required as these protocols allow users to connect to their mailboxes from remote locations.
 IMAP offers several advantages over POP.
 These include the ability to store a copy of messages on a remote server after they are downloaded and concurrent updates.
 IMAP can be useful over low-speed links as it allows users to fetch the structure of messages without downloading them.
 It can also perform tasks such as searching on the server in order to minimize data transfer between clients and servers.
 +
 Several POP and IMAP servers are available in the Ports Collection.
 These include package:mail/qpopper[], package:mail/imap-uw[], package:mail/courier-imap[], and package:mail/dovecot2[].
 +
 [WARNING]
 ====
 It should be noted that both POP and IMAP transmit information, including username and password credentials, in clear-text.
 To secure the transmission of information across these protocols, consider tunneling sessions over man:ssh[1] (crossref:security[security-ssh-tunneling,"SSH Tunneling"]) or using SSL (crossref:security[openssl,"OpenSSL"]).
 ====
 
 Domain Name System (DNS)::
 The Domain Name System (DNS) and its daemon `named` play a large role in the delivery of email.
 In order to deliver mail from one site to another, the MTA will look up the remote site in DNS to determine which host will receive mail for the destination. 
 This process also occurs when mail is sent from a remote host to the MTA.
 +
 In addition to mapping hostnames to IP addresses, DNS is responsible for storing information specific to mail delivery, known as Mail eXchanger MX records.
 The MX record specifies which hosts will receive mail for a particular domain.
 +
 To view the MX records for a domain, specify the type of record.
 Refer to man:host[1], for more details about this command:
 +
 [source,shell]
 ....
 % host -t mx FreeBSD.org
 FreeBSD.org mail is handled by 10 mx1.FreeBSD.org
 ....
 +
 Refer to crossref:network-servers[network-dns,"Domain Name System (DNS)"] for more information about DNS and its configuration.
 
 [[sendmail]]
 == Sendmail Configuration Files
 
 Sendmail is the default MTA installed with FreeBSD. It accepts mail from MUAs and delivers it to the appropriate mail host, as defined by its configuration. 
 Sendmail can also accept network connections and deliver mail to local mailboxes or to another program.
 
 The configuration files for Sendmail are located in [.filename]#/etc/mail#.
 This section describes these files in more detail.
 
 [.filename]#/etc/mail/access#::
 This access database file defines which hosts or IP addresses have access to the local mail server and what kind of access they have.
 Hosts listed as `OK`, which is the default option, are allowed to send mail to this host as long as the mail's final destination is the local machine.
 Hosts listed as `REJECT` are rejected for all mail connections.
 Hosts listed as `RELAY` are allowed to send mail for any destination using this mail server.
 Hosts listed as `ERROR` will have their mail returned with the specified mail error.
 If a host is listed as `SKIP`, Sendmail will abort the current search for this entry without accepting or rejecting the mail.
 Hosts listed as `QUARANTINE` will have their messages held and will receive the specified text as the reason for the hold.
 +
 Examples of using these options for both IPv4 and IPv6 addresses can be found in the FreeBSD sample configuration, [.filename]#/etc/mail/access.sample#:
 +
 [.programlisting]
 ....
 # $FreeBSD$
 #
 # Mail relay access control list.  Default is to reject mail unless the
 # destination is local, or listed in /etc/mail/local-host-names
 #
 ## Examples (commented out for safety)
 #From:cyberspammer.com          ERROR:"550 We don't accept mail from spammers"
 #From:okay.cyberspammer.com     OK
 #Connect:sendmail.org           RELAY
 #To:sendmail.org                RELAY
 #Connect:128.32                 RELAY
 #Connect:128.32.2               SKIP
 #Connect:IPv6:1:2:3:4:5:6:7     RELAY
 #Connect:suspicious.example.com QUARANTINE:Mail from suspicious host
 #Connect:[127.0.0.3]            OK
 #Connect:[IPv6:1:2:3:4:5:6:7:8] OK
 ....
 +
 To configure the access database, use the format shown in the sample to make entries in [.filename]#/etc/mail/access#, but do not put a comment symbol (`#`) in front of the entries.
 Create an entry for each host or network whose access should be configured.
 Mail senders that match the left side of the table are affected by the action on the right side of the table.
 +
 Whenever this file is updated, update its database and restart Sendmail:
 +
 [source,shell]
 ....
 # makemap hash /etc/mail/access < /etc/mail/access
 # service sendmail restart
 ....
 
 [.filename]#/etc/mail/aliases#::
 This database file contains a list of virtual mailboxes that are expanded to users, files, programs, or other aliases.
 Here are a few entries to illustrate the file format:
 +
 [.programlisting]
 ....
 root: localuser
 ftp-bugs: joe,eric,paul
 bit.bucket:  /dev/null
 procmail: "|/usr/local/bin/procmail"
 ....
 +
 The mailbox name on the left side of the colon is expanded to the target(s) on the right.
 The first entry expands the `root` mailbox to the `localuser` mailbox, which is then looked up in the [.filename]#/etc/mail/aliases# database.
 If no match is found, the message is delivered to `localuser`.
 The second entry shows a mail list.
 Mail to `ftp-bugs` is expanded to the three local mailboxes `joe`, `eric`, and `paul`.
 A remote mailbox could be specified as _user@example.com_.
 The third entry shows how to write mail to a file, in this case [.filename]#/dev/null#.
 The last entry demonstrates how to send mail to a program, [.filename]#/usr/local/bin/procmail#, through a UNIX(R) pipe.
 Refer to man:aliases[5] for more information about the format of this file.
 +
 Whenever this file is updated, run `newaliases` to update and initialize the aliases database.
 
 [.filename]#/etc/mail/sendmail.cf#::
 This is the master configuration file for Sendmail.
 It controls the overall behavior of Sendmail, including everything from rewriting email addresses to printing rejection messages to remote mail servers. 
 Accordingly, this configuration file is quite complex.
 Fortunately, this file rarely needs to be changed for standard mail servers.
 +
 The master Sendmail configuration file can be built from man:m4[1] macros that define the features and behavior of Sendmail.
 Refer to [.filename]#/usr/src/contrib/sendmail/cf/README# for some of the details.
 +
 Whenever changes to this file are made, Sendmail needs to be restarted for the changes to take effect.
 
 [.filename]#/etc/mail/virtusertable#::
 This database file maps mail addresses for virtual domains and users to real mailboxes.
 These mailboxes can be local, remote, aliases defined in [.filename]#/etc/mail/aliases#, or files.
 This allows multiple virtual domains to be hosted on one machine.
 +
 FreeBSD provides a sample configuration file in [.filename]#/etc/mail/virtusertable.sample# to further demonstrate its format.
 The following example demonstrates how to create custom entries using that format:
 +
 [.programlisting]
 ....
 root@example.com                root
 postmaster@example.com          postmaster@noc.example.net
 @example.com                    joe
 ....
 +
 This file is processed in a first match order.
 When an email address matches the address on the left, it is mapped to the local mailbox listed on the right.
 The format of the first entry in this example maps a specific email address to a local mailbox, whereas the format of the second entry maps a specific email address to a remote mailbox.
 Finally, any email address from `example.com` which has not matched any of the previous entries will match the last mapping and be sent to the local mailbox `joe`.
 When creating custom entries, use this format and add them to [.filename]#/etc/mail/virtusertable#.
 Whenever this file is edited, update its database and restart Sendmail:
 +
 [source,shell]
 ....
 # makemap hash /etc/mail/virtusertable < /etc/mail/virtusertable
 # service sendmail restart
 ....
 
 [.filename]#/etc/mail/relay-domains#::
 In a default FreeBSD installation, Sendmail is configured to only send mail from the host it is running on.
 For example, if a POP server is available, users will be able to check mail from remote locations but they will not be able to send outgoing emails from outside locations.
 Typically, a few moments after the attempt, an email will be sent from `MAILER-DAEMON` with a `5.7 Relaying Denied` message.
 +
 The most straightforward solution is to add the ISP's FQDN to [.filename]#/etc/mail/relay-domains#.
 If multiple addresses are needed, add them one per line:
 +
 [.programlisting]
 ....
 your.isp.example.com
 other.isp.example.net
 users-isp.example.org
 www.example.org
 ....
 +
 After creating or editing this file, restart Sendmail with `service sendmail restart`.
 +
 Now any mail sent through the system by any host in this list, provided the user has an account on the system, will succeed.
 This allows users to send mail from the system remotely without opening the system up to relaying SPAM from the Internet.
 
 [[mail-changingmta]]
 == Changing the Mail Transfer Agent
 
 FreeBSD comes with Sendmail already installed as the MTA which is in charge of outgoing and incoming mail.
 However, the system administrator can change the system's MTA.
 A wide choice of alternative MTAs is available from the `mail` category of the FreeBSD Ports Collection.
 
 Once a new MTA is installed, configure and test the new software before replacing Sendmail.
 Refer to the documentation of the new MTA for information on how to configure the software.
 
 Once the new MTA is working, use the instructions in this section to disable Sendmail and configure FreeBSD to use the replacement MTA.
 
 [[mail-disable-sendmail]]
 === Disable Sendmail
 
 [WARNING]
 ====
 
 If Sendmail's outgoing mail service is disabled, it is important that it is replaced with an alternative mail delivery system.
 Otherwise, system functions such as man:periodic[8] will be unable to deliver their results by email.
 Many parts of the system expect a functional MTA.
 If applications continue to use Sendmail's binaries to try to send email after they are disabled, mail could go into an inactive Sendmail queue and never be delivered.
 ====
 
 In order to completely disable Sendmail, add or edit the following lines in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 sendmail_enable="NO"
 sendmail_submit_enable="NO"
 sendmail_outbound_enable="NO"
 sendmail_msp_queue_enable="NO"
 ....
 
 To only disable Sendmail's incoming mail service, use only this entry in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 sendmail_enable="NO"
 ....
 
 More information on Sendmail's startup options is available in man:rc.sendmail[8].
 
 === Replace the Default MTA
 
 When a new MTA is installed using the Ports Collection, its startup script is also installed and startup instructions are mentioned in its package message. 
 Before starting the new MTA, stop the running Sendmail processes.
 This example stops all of these services, then starts the Postfix service:
 
 [source,shell]
 ....
 # service sendmail stop
 # service postfix start
 ....
 
 To start the replacement MTA at system boot, add its configuration line to [.filename]#/etc/rc.conf#.
 This entry enables the Postfix MTA:
 
 [.programlisting]
 ....
 postfix_enable="YES"
 ....
 
 Some extra configuration is needed as Sendmail is so ubiquitous that some software assumes it is already installed and configured.
 Check [.filename]#/etc/periodic.conf# and make sure that these values are set to `NO`.
 If this file does not exist, create it with these entries:
 
 [.programlisting]
 ....
 daily_clean_hoststat_enable="NO"
 daily_status_mail_rejects_enable="NO"
 daily_status_include_submit_mailq="NO"
 daily_submit_queuerun="NO"
 ....
 
 Some alternative MTAs provide their own compatible implementations of the Sendmail command-line interface in order to facilitate using them as drop-in replacements for Sendmail.
 However, some MUAs may try to execute standard Sendmail binaries instead of the new MTA's binaries.
 FreeBSD uses [.filename]#/etc/mail/mailer.conf# to map the expected Sendmail binaries to the location of the new binaries.
 More information about this mapping can be found in man:mailwrapper[8].
 
 The default [.filename]#/etc/mail/mailer.conf# looks like this:
 
 [.programlisting]
 ....
 # $FreeBSD$
 #
 # Execute the "real" sendmail program, named /usr/libexec/sendmail/sendmail
 #
 sendmail        /usr/libexec/sendmail/sendmail
 send-mail       /usr/libexec/sendmail/sendmail
 mailq           /usr/libexec/sendmail/sendmail
 newaliases      /usr/libexec/sendmail/sendmail
 hoststat        /usr/libexec/sendmail/sendmail
 purgestat       /usr/libexec/sendmail/sendmail
 ....
 
 When any of the commands listed on the left are run, the system actually executes the associated command shown on the right.
 This system makes it easy to change what binaries are executed when these default binaries are invoked.
 
 Some MTAs, when installed using the Ports Collection, will prompt to update this file for the new binaries.
 For example, Postfix will update the file like this:
 
 [.programlisting]
 ....
 #
 # Execute the Postfix sendmail program, named /usr/local/sbin/sendmail
 #
 sendmail        /usr/local/sbin/sendmail
 send-mail       /usr/local/sbin/sendmail
 mailq           /usr/local/sbin/sendmail
 newaliases      /usr/local/sbin/sendmail
 ....
 
 If the installation of the MTA does not automatically update [.filename]#/etc/mail/mailer.conf#, edit this file in a text editor so that it points to the new binaries.
 This example points to the binaries installed by package:mail/ssmtp[]:
 
 [.programlisting]
 ....
 sendmail        /usr/local/sbin/ssmtp
 send-mail       /usr/local/sbin/ssmtp
 mailq           /usr/local/sbin/ssmtp
 newaliases      /usr/local/sbin/ssmtp
 hoststat        /usr/bin/true
 purgestat       /usr/bin/true
 ....
 
 Once everything is configured, it is recommended to reboot the system.
 Rebooting provides the opportunity to ensure that the system is correctly configured to start the new MTA automatically on boot.
 
 [[mail-trouble]]
 == Troubleshooting
 
 === Why do I have to use the FQDN for hosts on my site?
 
 The host may actually be in a different domain.
 For example, in order for a host in `foo.bar.edu` to reach a host called `mumble` in the `bar.edu` domain, refer to it by the Fully-Qualified Domain Name FQDN, `mumble.bar.edu`, instead of just `mumble`.
 
 This is because the version of BIND which ships with FreeBSD no longer provides default abbreviations for non-FQDNs other than the local domain.
 An unqualified host such as `mumble` must either be found as `mumble.foo.bar.edu`, or it will be searched for in the root domain.
 
 In older versions of BIND, the search continued across `mumble.bar.edu`, and `mumble.edu`.
 RFC 1535 details why this is considered bad practice or even a security hole.
 
 As a good workaround, place the line:
 
 [.programlisting]
 ....
 search foo.bar.edu bar.edu
 ....
 
 instead of the previous:
 
 [.programlisting]
 ....
 domain foo.bar.edu
 ....
 
 into [.filename]#/etc/resolv.conf#.
 However, make sure that the search order does not go beyond the "boundary between local and public administration", as RFC 1535 calls it.
 
 === How can I run a mail server on a dial-up PPP host?
 
 Connect to a FreeBSD mail gateway on the LAN. The PPP connection is non-dedicated.
 
 One way to do this is to get a full-time Internet server to provide secondary MX services for the domain.
 In this example, the domain is `example.com` and the ISP has configured `example.net` to provide secondary MX services to the domain:
 
 [.programlisting]
 ....
 example.com.          MX        10      example.com.
                       MX        20      example.net.
 ....
 
 Only one host should be specified as the final recipient.
 For Sendmail, add `Cw example.com` in [.filename]#/etc/mail/sendmail.cf# on `example.com`.
 
 When the sending MTA attempts to deliver mail, it will try to connect to the system, `example.com`, over the PPP link.
 This will time out if the destination is offline.
 The MTA will automatically deliver it to the secondary MX site at the Internet Service Provider (ISP), `example.net`.
 The secondary MX site will periodically try to connect to the primary MX host, `example.com`.
 
 Use something like this as a login script:
 
 [.programlisting]
 ....
 #!/bin/sh
 # Put me in /usr/local/bin/pppmyisp
 ( sleep 60 ; /usr/sbin/sendmail -q ) &
 /usr/sbin/ppp -direct pppmyisp
 ....
 
 When creating a separate login script for users, instead use `sendmail -qRexample.com` in the script above.
 This will force all mail in the queue for `example.com` to be processed immediately.
 
 A further refinement of the situation can be seen from this example from the {freebsd-isp}:
 
 [.programlisting]
 ....
 > we provide the secondary MX for a customer. The customer connects to
 > our services several times a day automatically to get the mails to
 > his primary MX (We do not call his site when a mail for his domains
 > arrived). Our sendmail sends the mailqueue every 30 minutes. At the
 > moment he has to stay 30 minutes online to be sure that all mail is
 > gone to the primary MX.
 >
 > Is there a command that would initiate sendmail to send all the mails
 > now? The user has not root-privileges on our machine of course.
 
 In the privacy flags section of sendmail.cf, there is a
 definition Opgoaway,restrictqrun
 
 Remove restrictqrun to allow non-root users to start the queue processing.
 You might also like to rearrange the MXs. We are the 1st MX for our
 customers like this, and we have defined:
 
 # If we are the best MX for a host, try directly instead of generating
 # local config error.
 OwTrue
 
 That way a remote site will deliver straight to you, without trying
 the customer connection.  You then send to your customer.  Only works for
 hosts, so you need to get your customer to name their mail
 machine customer.com as well as
 hostname.customer.com in the DNS.  Just put an A record in
 the DNS for customer.com.
 ....
 
 [[mail-advanced]]
 == Advanced Topics
 
 This section covers more involved topics such as mail configuration and setting up mail for an entire domain.
 
 [[mail-config]]
 === Basic Configuration
 
 Out of the box, one can send email to external hosts as long as [.filename]#/etc/resolv.conf# is configured or the network has access to a configured DNS server.
 To have email delivered to the MTA on the FreeBSD host, do one of the following:
 
 * Run a DNS server for the domain.
 * Get mail delivered directly to the FQDN for the machine.
 
 In order to have mail delivered directly to a host, it must have a permanent static IP address, not a dynamic IP address.
 If the system is behind a firewall, it must be configured to allow SMTP traffic.
 To receive mail directly at a host, one of these two must be configured:
 
 * Make sure that the lowest-numbered MX record in DNS points to the host's static IP address.
 * Make sure there is no MX entry in the DNS for the host.
 
 Either of the above will allow mail to be received directly at the host.
 
 Try this:
 
 [source,shell]
 ....
 # hostname
 example.FreeBSD.org
 # host example.FreeBSD.org
 example.FreeBSD.org has address 204.216.27.XX
 ....
 
 In this example, mail sent directly to mailto:yourlogin@example.FreeBSD.org[yourlogin@example.FreeBSD.org] should work without problems, assuming Sendmail is running correctly on `example.FreeBSD.org`.
 
 For this example:
 
 [source,shell]
 ....
 # host example.FreeBSD.org
 example.FreeBSD.org has address 204.216.27.XX
 example.FreeBSD.org mail is handled (pri=10) by nevdull.FreeBSD.org
 ....
 
 All mail sent to `example.FreeBSD.org` will be collected on `hub` under the same username instead of being sent directly to your host.
 
 The above information is handled by the DNS server.
 The DNS record that carries mail routing information is the MX entry.
 If no MX record exists, mail will be delivered directly to the host by way of its IP address.
 
 The MX entry for `freefall.FreeBSD.org` at one time looked like this:
 
 [.programlisting]
 ....
 freefall		MX	30	mail.crl.net
 freefall		MX	40	agora.rdrop.com
 freefall		MX	10	freefall.FreeBSD.org
 freefall		MX	20	who.cdrom.com
 ....
 
 `freefall` had many MX entries.
 The lowest MX number is the host that receives mail directly, if available.
 If it is not accessible for some reason, the next lower-numbered host will accept messages temporarily, and pass it along when a lower-numbered host becomes available.
 
 Alternate MX sites should have separate Internet connections in order to be most useful.
 Your ISP can provide this service.
 
 [[mail-domain]]
 === Mail for a Domain
 
 When configuring a MTA for a network, any mail sent to hosts in its domain should be diverted to the MTA so that users can receive their mail on the master mail server.
 
 To make life easiest, a user account with the same _username_ should exist on both the MTA and the system with the MUA.
 Use man:adduser[8] to create the user accounts.
 
 The MTA must be the designated mail exchanger for each workstation on the network.
 This is done in the DNS configuration with an MX record:
 
 [.programlisting]
 ....
 example.FreeBSD.org	A	204.216.27.XX		; Workstation
 			MX	10 nevdull.FreeBSD.org	; Mailhost
 ....
 
 This will redirect mail for the workstation to the MTA no matter where the A record points.
 The mail is sent to the MX host.
 
 This must be configured on a DNS server.
 If the network does not run its own DNS server, talk to the ISP or DNS provider.
 
 The following is an example of virtual email hosting.
 Consider a customer with the domain `customer1.org`, where all the mail for `customer1.org` should be sent to `mail.myhost.com`.
 The DNS entry should look like this:
 
 [.programlisting]
 ....
 customer1.org		MX	10	mail.myhost.com
 ....
 
 An `A` record is _not_ needed for `customer1.org` in order to only handle email for that domain.
 However, running `ping` against `customer1.org` will not work unless an `A` record exists for it.
 
 Tell the MTA which domains and/or hostnames it should accept mail for.
 Either of the following will work for Sendmail:
 
 * Add the hosts to [.filename]#/etc/mail/local-host-names# when using the `FEATURE(use_cw_file)`.
 * Add a `Cwyour.host.com` line to [.filename]#/etc/sendmail.cf#.
 
 [[outgoing-only]]
 == Setting Up to Send Only
 
 There are many instances where one may only want to send mail through a relay.
 Some examples are:
 
 * The computer is a desktop machine that needs to use programs such as man:mail[1], using the ISP's mail relay.
 * The computer is a server that does not handle mail locally, but needs to pass off all mail to a relay for processing.
 
 While any MTA is capable of filling this particular niche, it can be difficult to properly configure a full-featured MTA just to handle offloading mail.
 Programs such as Sendmail and Postfix are overkill for this use.
 
 Additionally, a typical Internet access service agreement may forbid one from running a "mail server".
 
 The easiest way to fulfill those needs is to install the package:mail/ssmtp[] port:
 
 [source,shell]
 ....
 # cd /usr/ports/mail/ssmtp
 # make install replace clean
 ....
 
 Once installed, package:mail/ssmtp[] can be configured with [.filename]#/usr/local/etc/ssmtp/ssmtp.conf#:
 
 [.programlisting]
 ....
 root=yourrealemail@example.com
 mailhub=mail.example.com
 rewriteDomain=example.com
 hostname=_HOSTNAME_
 ....
 
 Use the real email address for `root`.
 Enter the ISP's outgoing mail relay in place of `mail.example.com`.
 Some ISPs call this the "outgoing mail server" or "SMTP server".
 
 Make sure to disable Sendmail, including the outgoing mail service.
 See <<mail-disable-sendmail>> for details.
 
 package:mail/ssmtp[] has some other options available. Refer to the examples in [.filename]#/usr/local/etc/ssmtp# or the manual page of ssmtp for more information.
 
 Setting up ssmtp in this manner allows any software on the computer that needs to send mail to function properly, while not violating the ISP's usage policy or allowing the computer to be hijacked for spamming.
 
 [[SMTP-dialup]]
 == Using Mail with a Dialup Connection
 
 When using a static IP address, one should not need to adjust the default configuration.
 Set the hostname to the assigned Internet name and Sendmail will do the rest.
 
 When using a dynamically assigned IP address and a dialup PPP connection to the Internet, one usually has a mailbox on the ISP's mail server.
 In this example, the ISP's domain is `example.net`, the user name is `user`, the hostname is `bsd.home`, and the ISP has allowed `relay.example.net` as a mail relay.
 
 In order to retrieve mail from the ISP's mailbox, install a retrieval agent from the Ports Collection. package:mail/fetchmail[] is a good choice as it supports many different protocols.
 Usually, the ISP will provide POP.
 When using user PPP, email can be automatically fetched when an Internet connection is established with the following entry in [.filename]#/etc/ppp/ppp.linkup#:
 
 [.programlisting]
 ....
 MYADDR:
 !bg su user -c fetchmail
 ....
 
 When using Sendmail to deliver mail to non-local accounts, configure Sendmail to process the mail queue as soon as the Internet connection is established.
 To do this, add this line after the above `fetchmail` entry in [.filename]#/etc/ppp/ppp.linkup#:
 
 [.programlisting]
 ....
   !bg su user -c "sendmail -q"
 ....
 
 In this example, there is an account for `user` on `bsd.home`.
 In the home directory of `user` on `bsd.home`, create a [.filename]#.fetchmailrc# which contains this line:
 
 [.programlisting]
 ....
 poll example.net protocol pop3 fetchall pass MySecret
 ....
 
 This file should not be readable by anyone except `user` as it contains the password `MySecret`.
 
 In order to send mail with the correct `from:` header, configure Sendmail to use mailto:user@example.net[user@example.net] rather than mailto:user@bsd.home[user@bsd.home] and to send all mail via `relay.example.net`, allowing quicker mail transmission.
 
 The following [.filename]#.mc# should suffice:
 
 [.programlisting]
 ....
 VERSIONID(`bsd.home.mc version 1.0')
 OSTYPE(bsd4.4)dnl
 FEATURE(nouucp)dnl
 MAILER(local)dnl
 MAILER(smtp)dnl
 Cwlocalhost
 Cwbsd.home
 MASQUERADE_AS(`example.net')dnl
 FEATURE(allmasquerade)dnl
 FEATURE(masquerade_envelope)dnl
 FEATURE(nocanonify)dnl
 FEATURE(nodns)dnl
 define(`SMART_HOST', `relay.example.net')
 Dmbsd.home
 define(`confDOMAIN_NAME',`bsd.home')dnl
 define(`confDELIVERY_MODE',`deferred')dnl
 ....
 
 Refer to the previous section for details of how to convert this file into the [.filename]#sendmail.cf# format.
 Do not forget to restart Sendmail after updating [.filename]#sendmail.cf#.
 
 [[SMTP-Auth]]
 == SMTP Authentication
 
 Configuring SMTP authentication on the MTA provides a number of benefits.
 SMTP authentication adds a layer of security to Sendmail, and provides mobile users who switch hosts the ability to use the same MTA without the need to reconfigure their mail client's settings each time.
 
 [.procedure]
 . Install package:security/cyrus-sasl2[] from the Ports Collection. This port supports a number of compile-time options. For the SMTP authentication method demonstrated in this example, make sure that `LOGIN` is not disabled.
 . After installing package:security/cyrus-sasl2[], edit [.filename]#/usr/local/lib/sasl2/Sendmail.conf#, or create it if it does not exist, and add the following line:
 +
 [.programlisting]
 ....
 pwcheck_method: saslauthd
 ....
 
 . Next, install package:security/cyrus-sasl2-saslauthd[] and add the following line to [.filename]#/etc/rc.conf#:
 +
 [.programlisting]
 ....
 saslauthd_enable="YES"
 ....
-+ 
++
 Finally, start the saslauthd daemon:
 +
 [source,shell]
 ....
 # service saslauthd start
 ....
-+ 
++
 This daemon serves as a broker for Sendmail to authenticate against the FreeBSD man:passwd[5] database.
 This saves the trouble of creating a new set of usernames and passwords for each user that needs to use SMTP authentication, and keeps the login and mail password the same.
 . Next, edit [.filename]#/etc/make.conf# and add the following lines:
 +
 [.programlisting]
 ....
 SENDMAIL_CFLAGS=-I/usr/local/include/sasl -DSASL
 SENDMAIL_LDADD=/usr/local/lib/libsasl2.so
 ....
-+ 
++
 These lines provide Sendmail the proper configuration options for linking to package:cyrus-sasl2[] at compile time.
 Make sure that package:cyrus-sasl2[] has been installed before recompiling Sendmail.
 . Recompile Sendmail by executing the following commands:
 +
 [source,shell]
 ....
 # cd /usr/src/lib/libsmutil
 # make cleandir && make obj && make
 # cd /usr/src/lib/libsm
 # make cleandir && make obj && make
 # cd /usr/src/usr.sbin/sendmail
 # make cleandir && make obj && make && make install
 ....
-+ 
++
 This compile should not have any problems if [.filename]#/usr/src# has not changed extensively and the shared libraries it needs are available.
 . After Sendmail has been compiled and reinstalled, edit [.filename]#/etc/mail/freebsd.mc# or the local [.filename]#.mc#. Many administrators choose to use the output from man:hostname[1] as the name of [.filename]#.mc# for uniqueness. Add these lines:
 +
 [.programlisting]
 ....
 dnl set SASL options
 TRUST_AUTH_MECH(`GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
 define(`confAUTH_MECHANISMS', `GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
 ....
-+ 
++
 These options configure the different methods available to Sendmail for authenticating users.
 To use a method other than pwcheck, refer to the Sendmail documentation.
 . Finally, run man:make[1] while in [.filename]#/etc/mail#. That will run the new [.filename]#.mc# and create a [.filename]#.cf# named either [.filename]#freebsd.cf# or the name used for the local [.filename]#.mc#. Then, run `make install restart`, which will copy the file to [.filename]#sendmail.cf#, and properly restart Sendmail. For more information about this process, refer to [.filename]#/etc/mail/Makefile#.
 
 To test the configuration, use a MUA to send a test message.
 For further investigation, set the `LogLevel` of Sendmail to `13` and watch [.filename]#/var/log/maillog# for any errors.
 
 For more information, refer to http://www.sendmail.org/~ca/email/auth.html[SMTP authentication].
 
 [[mail-agents]]
 == Mail User Agents
 
 A MUA is an application that is used to send and receive email.
 As email "evolves" and becomes more complex, MUAs are becoming increasingly powerful and provide users increased functionality and flexibility.
 The `mail` category of the FreeBSD Ports Collection contains numerous MUAs.
 These include graphical email clients such as Evolution or Balsa and console based clients such as mutt or alpine.
 
 [[mail-command]]
 === `mail`
 
 man:mail[1] is the default MUA installed with FreeBSD. It is a console based MUA that offers the basic functionality required to send and receive text-based email.
 It provides limited attachment support and can only access local mailboxes.
 
 Although `mail` does not natively support interaction with POP or IMAP servers, these mailboxes may be downloaded to a local [.filename]#mbox# using an application such as fetchmail.
 
 In order to send and receive email, run `mail`:
 
 [source,shell]
 ....
 % mail
 ....
 
 The contents of the user's mailbox in [.filename]#/var/mail# are automatically read by `mail`.
 Should the mailbox be empty, the utility exits with a message indicating that no mail could be found.
 If mail exists, the application interface starts, and a list of messages will be displayed.
 Messages are automatically numbered, as can be seen in the following example:
 
 [source,shell]
 ....
 Mail version 8.1 6/6/93.  Type ? for help.
 "/var/mail/marcs": 3 messages 3 new
 >N  1 root@localhost        Mon Mar  8 14:05  14/510   "test"
  N  2 root@localhost        Mon Mar  8 14:05  14/509   "user account"
  N  3 root@localhost        Mon Mar  8 14:05  14/509   "sample"
 ....
 
 Messages can now be read by typing kbd:[t] followed by the message number.
 This example reads the first email:
 
 [source,shell]
 ....
 & t 1
 Message 1:
 From root@localhost  Mon Mar  8 14:05:52 2004
 X-Original-To: marcs@localhost
 Delivered-To: marcs@localhost
 To: marcs@localhost
 Subject: test
 Date: Mon,  8 Mar 2004 14:05:52 +0200 (SAST)
 From: root@localhost (Charlie Root)
 
 This is a test message, please reply if you receive it.
 ....
 
 As seen in this example, the message will be displayed with full headers.
 To display the list of messages again, press kbd:[h].
 
 If the email requires a reply, press either kbd:[R] or kbd:[r] `mail` keys.
 kbd:[R] instructs `mail` to reply only to the sender of the email, while kbd:[r] replies to all other recipients of the message.
 These commands can be suffixed with the mail number of the message to reply to.
 After typing the response, the end of the message should be marked by a single kbd:[.] on its own line.
 An example can be seen below:
 
 [source,shell]
 ....
 & R 1
 To: root@localhost
 Subject: Re: test
 
 Thank you, I did get your email.
 .
 EOT
 ....
 
 In order to send a new email, press kbd:[m], followed by the recipient email address.
 Multiple recipients may be specified by separating each address with the kbd:[,] delimiter.
 The subject of the message may then be entered, followed by the message contents.
 The end of the message should be specified by putting a single kbd:[.] on its own line.
 
 [source,shell]
 ....
 & mail root@localhost
 Subject: I mastered mail
 
 Now I can send and receive email using mail ... :)
 .
 EOT
 ....
 
 While using `mail`, press kbd:[?] to display help at any time.
 Refer to man:mail[1] for more help on how to use `mail`.
 
 [NOTE]
 ====
 man:mail[1] was not designed to handle attachments and thus deals with them poorly.
 Newer MUAs handle attachments in a more intelligent way.
 Users who prefer to use `mail` may find the package:converters/mpack[] port to be of considerable use.
 ====
 
 [[mutt-command]]
 === mutt
 
 mutt is a powerful MUA, with many features, including:
 
 * The ability to thread messages.
 * PGP support for digital signing and encryption of email.
 * MIME support.
 * Maildir support.
 * Highly customizable.
 
 Refer to http://www.mutt.org[http://www.mutt.org] for more information on mutt.
 
 mutt may be installed using the package:mail/mutt[] port.
 After the port has been installed, mutt can be started by issuing the following command:
 
 [source,shell]
 ....
 % mutt
 ....
 
 mutt will automatically read and display the contents of the user mailbox in [.filename]#/var/mail#.
 If no mails are found, mutt will wait for commands from the user.
 The example below shows mutt displaying a list of messages:
 
 image::mutt1.png[]
 
 To read an email, select it using the cursor keys and press kbd:[Enter].
 An example of mutt displaying email can be seen below:
 
 image::mutt2.png[]
 
 Similar to man:mail[1], mutt can be used to reply only to the sender of the message as well as to all recipients.
 To reply only to the sender of the email, press kbd:[r].
 To send a group reply to the original sender as well as all the message recipients, press kbd:[g].
 
 [NOTE]
 ====
 By default, mutt uses the man:vi[1] editor for creating and replying to emails.
 Each user can customize this by creating or editing the [.filename]#.muttrc# in their home directory and setting the `editor` variable or by setting the `EDITOR` environment variable.
 Refer to http://www.mutt.org/[http://www.mutt.org/] for more information about configuring mutt.
 ====
 
 To compose a new mail message, press kbd:[m].
 After a valid subject has been given, mutt will start man:vi[1] so the email can be written.
 Once the contents of the email are complete, save and quit from `vi`.
 mutt will resume, displaying a summary screen of the mail that is to be delivered.
 In order to send the mail, press kbd:[y].
 An example of the summary screen can be seen below:
 
 image::mutt3.png[]
 
 mutt contains extensive help which can be accessed from most of the menus by pressing kbd:[?].
 The top line also displays the keyboard shortcuts where appropriate.
 
 [[alpine-command]]
 === alpine
 
 alpine is aimed at a beginner user, but also includes some advanced features.
 
 [WARNING]
 ====
 alpine has had several remote vulnerabilities discovered in the past, which allowed remote attackers to execute arbitrary code as users on the local system, by the action of sending a specially-prepared email.
 While _known_ problems have been fixed, alpine code is written in an insecure style and the FreeBSD Security Officer believes there are likely to be other undiscovered vulnerabilities.
 Users install alpine at their own risk.
 ====
 
 The current version of alpine may be installed using the package:mail/alpine[] port.
 Once the port has installed, alpine can be started by issuing the following command:
 
 [source,shell]
 ....
 % alpine
 ....
 
 The first time alpine runs, it displays a greeting page with a brief introduction, as well as a request from the alpine development team to send an anonymous email message allowing them to judge how many users are using their client.
 To send this anonymous message, press kbd:[Enter].
 Alternatively, press kbd:[E] to exit the greeting without sending an anonymous message.
 An example of the greeting page is shown below:
 
 image::pine1.png[]
 
 The main menu is then presented, which can be navigated using the cursor keys.
 This main menu provides shortcuts for the composing new mails, browsing mail directories, and administering address book entries.
 Below the main menu, relevant keyboard shortcuts to perform functions specific to the task at hand are shown.
 
 The default directory opened by alpine is [.filename]#inbox#.
 To view the message index, press kbd:[I], or select the [.guimenuitem]#MESSAGE INDEX# option shown below:
 
 image::pine2.png[]
 
 The message index shows messages in the current directory and can be navigated by using the cursor keys.
 Highlighted messages can be read by pressing kbd:[Enter].
 
 image::pine3.png[]
 
 In the screenshot below, a sample message is displayed by alpine.
 Contextual keyboard shortcuts are displayed at the bottom of the screen.
 An example of one of a shortcut is kbd:[r], which tells the MUA to reply to the current message being displayed.
 
 image::pine4.png[]
 
 Replying to an email in alpine is done using the pico editor, which is installed by default with alpine.
 pico makes it easy to navigate the message and is easier for novice users to use than man:vi[1] or man:mail[1].
 Once the reply is complete, the message can be sent by pressing kbd:[Ctrl+X].
 alpine will ask for confirmation before sending the message.
 
 image::pine5.png[]
 
 alpine can be customized using the [.guimenuitem]#SETUP# option from the main menu.
 Consult http://www.washington.edu/alpine/[http://www.washington.edu/alpine/] for more information.
 
 [[mail-fetchmail]]
 == Using fetchmail
 
 fetchmail is a full-featured IMAP and POP client.
 It allows users to automatically download mail from remote IMAP and POP servers and save it into local mailboxes where it can be accessed more easily.
 fetchmail can be installed using the package:mail/fetchmail[] port, and offers various features, including:
 
 * Support for the POP3, APOP, KPOP, IMAP, ETRN and ODMR protocols.
 * Ability to forward mail using SMTP, which allows filtering, forwarding, and aliasing to function normally.
 * May be run in daemon mode to check periodically for new messages.
 * Can retrieve multiple mailboxes and forward them, based on configuration, to different local users.
 
 This section explains some of the basic features of fetchmail.
 This utility requires a [.filename]#.fetchmailrc# configuration in the user's home directory in order to run correctly.
 This file includes server information as well as login credentials.
 Due to the sensitive nature of the contents of this file, it is advisable to make it readable only by the user, with the following command:
 
 [source,shell]
 ....
 % chmod 600 .fetchmailrc
 ....
 
 The following [.filename]#.fetchmailrc# serves as an example for downloading a single user mailbox using POP.
 It tells fetchmail to connect to `example.com` using a username of `joesoap` and a password of `XXX`.
 This example assumes that the user `joesoap` exists on the local system.
 
 [.programlisting]
 ....
 poll example.com protocol pop3 username "joesoap" password "XXX"
 ....
 
 The next example connects to multiple POP and IMAP servers and redirects to different local usernames where applicable:
 
 [.programlisting]
 ....
 poll example.com proto pop3:
 user "joesoap", with password "XXX", is "jsoap" here;
 user "andrea", with password "XXXX";
 poll example2.net proto imap:
 user "john", with password "XXXXX", is "myth" here;
 ....
 
 fetchmail can be run in daemon mode by running it with `-d`, followed by the interval (in seconds) that fetchmail should poll servers listed in [.filename]#.fetchmailrc#.
 The following example configures fetchmail to poll every 600 seconds:
 
 [source,shell]
 ....
 % fetchmail -d 600
 ....
 
 More information on fetchmail can be found at http://www.fetchmail.info/[http://www.fetchmail.info/].
 
 [[mail-procmail]]
 == Using procmail
 
 procmail is a powerful application used to filter incoming mail.
 It allows users to define "rules" which can be matched to incoming mails to perform specific functions or to reroute mail to alternative mailboxes or email addresses.
 procmail can be installed using the package:mail/procmail[] port.
 Once installed, it can be directly integrated into most MTAs.
 Consult the MTA documentation for more information.
 Alternatively, procmail can be integrated by adding the following line to a [.filename]#.forward# in the home directory of the user:
 
 [.programlisting]
 ....
 "|exec /usr/local/bin/procmail || exit 75"
 ....
 
 The following section displays some basic procmail rules, as well as brief descriptions of what they do.
 Rules must be inserted into a [.filename]#.procmailrc#, which must reside in the user's home directory.
 
 The majority of these rules can be found in man:procmailex[5].
 
 To forward all mail from mailto:user@example.com[user@example.com] to an external address of mailto:goodmail@example2.com[goodmail@example2.com]:
 
 [.programlisting]
 ....
 :0
 * ^From.*user@example.com
 ! goodmail@example2.com
 ....
 
 To forward all mails shorter than 1000 bytes to an external address of mailto:goodmail@example2.com[goodmail@example2.com]:
 
 [.programlisting]
 ....
 :0
 * < 1000
 ! goodmail@example2.com
 ....
 
 To send all mail sent to mailto:alternate@example.com[alternate@example.com] to a mailbox called [.filename]#alternate#:
 
 [.programlisting]
 ....
 :0
 * ^TOalternate@example.com
 alternate
 ....
 
 To send all mail with a subject of "Spam" to [.filename]#/dev/null#:
 
 [.programlisting]
 ....
 :0
 ^Subject:.*Spam
 /dev/null
 ....
 
 A useful recipe that parses incoming `FreeBSD.org` mailing lists and places each list in its own mailbox:
 
 [.programlisting]
 ....
 :0
 * ^Sender:.owner-freebsd-\/[^@]+@FreeBSD.ORG
 {
 	LISTNAME=${MATCH}
 	:0
 	* LISTNAME??^\/[^@]+
 	FreeBSD-${MATCH}
 }
 ....
diff --git a/documentation/content/en/books/handbook/network-servers/_index.adoc b/documentation/content/en/books/handbook/network-servers/_index.adoc
index 1bce38f5c8..14a9e888b2 100644
--- a/documentation/content/en/books/handbook/network-servers/_index.adoc
+++ b/documentation/content/en/books/handbook/network-servers/_index.adoc
@@ -1,3010 +1,3010 @@
 ---
 title: Chapter 30. Network Servers
 part: IV. Network Communication
 prev: books/handbook/mail
 next: books/handbook/firewalls
 description: This chapter covers some of the more frequently used network services on UNIX systems
 tags: ["network", "servers", "inetd", "NFS", "NIS", "LDAP", "DHCP", "DNS", "Apache HTTP", "FTP", "Samba", "NTP", "iSCSI"]
 ---
 
 [[network-servers]]
 = Network Servers
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 30
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/network-servers/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/network-servers/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/network-servers/
 endif::[]
 
 include::shared/authors.adoc[]
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 toc::[]
 
 [[network-servers-synopsis]]
 == Synopsis
 
 This chapter covers some of the more frequently used network services on UNIX(R) systems.
 This includes installing, configuring, testing, and maintaining many different types of network services.
 Example configuration files are included throughout this chapter for reference.
 
 By the end of this chapter, readers will know:
 
 * How to manage the inetd daemon.
 * How to set up the Network File System (NFS).
 * How to set up the Network Information Server (NIS) for centralizing and sharing user accounts.
 * How to set FreeBSD up to act as an LDAP server or client
 * How to set up automatic network settings using DHCP.
 * How to set up a Domain Name Server (DNS).
 * How to set up the Apache HTTP Server.
 * How to set up a File Transfer Protocol (FTP) server.
 * How to set up a file and print server for Windows(R) clients using Samba.
 * How to synchronize the time and date, and set up a time server using the Network Time Protocol (NTP).
 * How to set up iSCSI.
 
 This chapter assumes a basic knowledge of:
 
 * [.filename]#/etc/rc# scripts.
 * Network terminology.
 * Installation of additional third-party software (crossref:ports[ports,Installing Applications: Packages and Ports]).
 
 [[network-inetd]]
 == The inetd Super-Server
 
 The man:inetd[8] daemon is sometimes referred to as a Super-Server because it manages connections for many services.
 Instead of starting multiple applications, only the inetd service needs to be started.
 When a connection is received for a service that is managed by inetd, it determines which program the connection is destined for, spawns a process for that program, and delegates the program a socket.
 Using inetd for services that are not heavily used can reduce system load, when compared to running each daemon individually in stand-alone mode.
 
 Primarily, inetd is used to spawn other daemons, but several trivial protocols are handled internally, such as chargen, auth, time, echo, discard, and daytime.
 
 This section covers the basics of configuring inetd.
 
 [[network-inetd-conf]]
 === Configuration File
 
 Configuration of inetd is done by editing [.filename]#/etc/inetd.conf#.
 Each line of this configuration file represents an application which can be started by inetd.
 By default, every line starts with a comment (`#`), meaning that inetd is not listening for any applications.
 To configure inetd to listen for an application's connections, remove the `#` at the beginning of the line for that application.
 
 After saving your edits, configure inetd to start at system boot by editing [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 inetd_enable="YES"
 ....
 
 To start inetd now, so that it listens for the service you configured, type:
 
 [source,shell]
 ....
 # service inetd start
 ....
 
 Once inetd is started, it needs to be notified whenever a modification is made to [.filename]#/etc/inetd.conf#:
 
 [[network-inetd-reread]]
 .Reloading the inetd Configuration File
 [example]
 ====
 
 [source,shell]
 ....
 # service inetd reload
 ....
 
 ====
 
 Typically, the default entry for an application does not need to be edited beyond removing the `#`.
 In some situations, it may be appropriate to edit the default entry.
 
 As an example, this is the default entry for man:ftpd[8] over IPv4:
 
 [.programlisting]
 ....
 ftp     stream  tcp     nowait  root    /usr/libexec/ftpd       ftpd -l
 ....
 
 The seven columns in an entry are as follows:
 
 [.programlisting]
 ....
 service-name
 socket-type
 protocol
 {wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]
 user[:group][/login-class]
 server-program
 server-program-arguments
 ....
 
 where:
 
 service-name::
 The service name of the daemon to start.
 It must correspond to a service listed in [.filename]#/etc/services#.
 This determines which port inetd listens on for incoming connections to that service.
 When using a custom service, it must first be added to [.filename]#/etc/services#.
 
 socket-type::
 Either `stream`, `dgram`, `raw`, or `seqpacket`.
 Use `stream` for TCP connections and `dgram` for UDP services.
 
 protocol::
 Use one of the following protocol names:
 +
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | Protocol Name
 | Explanation
 
 
 |tcp or tcp4
 |TCP IPv4
 
 |udp or udp4
 |UDP IPv4
 
 |tcp6
 |TCP IPv6
 
 |udp6
 |UDP IPv6
 
 |tcp46
 |Both TCP IPv4 and IPv6
 
 |udp46
 |Both UDP IPv4 and IPv6
 |===
 
 {wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]::
 In this field, `wait` or `nowait` must be specified.
 `max-child`, `max-connections-per-ip-per-minute` and `max-child-per-ip` are optional.
 +
 `wait|nowait` indicates whether or not the service is able to handle its own socket.
 `dgram` socket types must use `wait` while `stream` daemons, which are usually multi-threaded, should use `nowait`.
 `wait` usually hands off multiple sockets to a single daemon, while `nowait` spawns a child daemon for each new socket.
 +
 The maximum number of child daemons inetd may spawn is set by `max-child`.
 For example, to limit ten instances of the daemon, place a `/10` after `nowait`.
 Specifying `/0` allows an unlimited number of children.
 +
 `max-connections-per-ip-per-minute` limits the number of connections from any particular IP address per minute.
 Once the limit is reached, further connections from this IP address will be dropped until the end of the minute.
 For example, a value of `/10` would limit any particular IP address to ten connection attempts per minute.
 `max-child-per-ip` limits the number of child processes that can be started on behalf on any single IP address at any moment.
 These options can limit excessive resource consumption and help to prevent Denial of Service attacks.
 +
 An example can be seen in the default settings for man:fingerd[8]:
 +
 [.programlisting]
 ....
 finger stream  tcp     nowait/3/10 nobody /usr/libexec/fingerd fingerd -k -s
 ....
 
 user::
 The username the daemon will run as.
 Daemons typically run as `root`, `daemon`, or `nobody`.
 
 server-program::
 The full path to the daemon.
 If the daemon is a service provided by inetd internally, use `internal`.
 
 server-program-arguments::
 Used to specify any command arguments to be passed to the daemon on invocation.
 If the daemon is an internal service, use `internal`.
 
 [[network-inetd-cmdline]]
 === Command-Line Options
 
 Like most server daemons, inetd has a number of options that can be used to modify its behavior.
 By default, inetd is started with `-wW -C 60`.
 These options enable TCP wrappers for all services, including internal services, and prevent any IP address from requesting any service more than 60 times per minute.
 
 To change the default options which are passed to inetd, add an entry for `inetd_flags` in [.filename]#/etc/rc.conf#.
 If inetd is already running, restart it with `service inetd restart`.
 
 The available rate limiting options are:
 
 -c maximum::
 Specify the default maximum number of simultaneous invocations of each service, where the default is unlimited.
 May be overridden on a per-service basis by using `max-child` in [.filename]#/etc/inetd.conf#.
 
 -C rate::
 Specify the default maximum number of times a service can be invoked from a single IP address per minute.
 May be overridden on a per-service basis by using `max-connections-per-ip-per-minute` in [.filename]#/etc/inetd.conf#.
 
 -R rate::
 Specify the maximum number of times a service can be invoked in one minute, where the default is `256`.
 A rate of `0` allows an unlimited number.
 
 -s maximum::
 Specify the maximum number of times a service can be invoked from a single IP address at any one time, where the default is unlimited.
 May be overridden on a per-service basis by using `max-child-per-ip` in [.filename]#/etc/inetd.conf#.
 
 Additional options are available. Refer to man:inetd[8] for the full list of options.
 
 [[network-inetd-security]]
 === Security Considerations
 
 Many of the daemons which can be managed by inetd are not security-conscious.
 Some daemons, such as fingerd, can provide information that may be useful to an attacker.
 Only enable the services which are needed and monitor the system for excessive connection attempts.
 `max-connections-per-ip-per-minute`, `max-child` and `max-child-per-ip` can be used to limit such attacks.
 
 By default, TCP wrappers is enabled.
 Consult man:hosts_access[5] for more information on placing TCP restrictions on various inetd invoked daemons.
 
 [[network-nfs]]
 == Network File System (NFS)
 
 FreeBSD supports the Network File System (NFS), which allows a server to share directories and files with clients over a network.
 With NFS, users and programs can access files on remote systems as if they were stored locally.
 
 NFS has many practical uses.
 Some of the more common uses include:
 
 * Data that would otherwise be duplicated on each client can be kept in a single location and accessed by clients on the network.
 * Several clients may need access to the [.filename]#/usr/ports/distfiles# directory. Sharing that directory allows for quick access to the source files without having to download them to each client.
 * On large networks, it is often more convenient to configure a central NFS server on which all user home directories are stored. Users can log into a client anywhere on the network and have access to their home directories.
 * Administration of NFS exports is simplified. For example, there is only one file system where security or backup policies must be set.
 * Removable media storage devices can be used by other machines on the network. This reduces the number of devices throughout the network and provides a centralized location to manage their security. It is often more convenient to install software on multiple machines from a centralized installation media.
 
 NFS consists of a server and one or more clients.
 The client remotely accesses the data that is stored on the server machine.
 In order for this to function properly, a few processes have to be configured and running.
 
 These daemons must be running on the server:
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | Daemon
 | Description
 
 
 |nfsd
 |The NFS daemon which services requests from NFS clients.
 
 |mountd
 |The NFS mount daemon which carries out requests received from nfsd.
 
 |rpcbind
 | This daemon allows NFS clients to discover which port the NFS server is using.
 |===
 
 Running man:nfsiod[8] on the client can improve performance, but is not required.
 
 [[network-configuring-nfs]]
 === Configuring the Server
 
 The file systems which the NFS server will share are specified in [.filename]#/etc/exports#.
 Each line in this file specifies a file system to be exported, which clients have access to that file system, and any access options.
 When adding entries to this file, each exported file system, its properties, and allowed hosts must occur on a single line.
 If no clients are listed in the entry, then any client on the network can mount that file system.
 
 The following [.filename]#/etc/exports# entries demonstrate how to export file systems.
 The examples can be modified to match the file systems and client names on the reader's network.
 There are many options that can be used in this file, but only a few will be mentioned here.
 See man:exports[5] for the full list of options.
 
 This example shows how to export [.filename]#/cdrom# to three hosts named _alpha_, _bravo_, and _charlie_:
 
 [.programlisting]
 ....
 /cdrom -ro alpha bravo charlie
 ....
 
 The `-ro` flag makes the file system read-only, preventing clients from making any changes to the exported file system.
 This example assumes that the host names are either in DNS or in [.filename]#/etc/hosts#.
 Refer to man:hosts[5] if the network does not have a DNS server.
 
 The next example exports [.filename]#/home# to three clients by IP address.
 This can be useful for networks without DNS or [.filename]#/etc/hosts# entries.
 The `-alldirs` flag allows subdirectories to be mount points.
 In other words, it will not automatically mount the subdirectories, but will permit the client to mount the directories that are required as needed.
 
 [.programlisting]
 ....
 /usr/home  -alldirs  10.0.0.2 10.0.0.3 10.0.0.4
 ....
 
 This next example exports [.filename]#/a# so that two clients from different domains may access that file system.
 The `-maproot=root` allows `root` on the remote system to write data on the exported file system as `root`.
 If `-maproot=root` is not specified, the client's `root` user will be mapped to the server's `nobody` account and will be subject to the access limitations defined for `nobody`.
 
 [.programlisting]
 ....
 /a  -maproot=root  host.example.com box.example.org
 ....
 
 A client can only be specified once per file system.
 For example, if [.filename]#/usr# is a single file system, these entries would be invalid as both entries specify the same host:
 
 [.programlisting]
 ....
 # Invalid when /usr is one file system
 /usr/src   client
 /usr/ports client
 ....
 
 The correct format for this situation is to use one entry:
 
 [.programlisting]
 ....
 /usr/src /usr/ports  client
 ....
 
 The following is an example of a valid export list, where [.filename]#/usr# and [.filename]#/exports# are local file systems:
 
 [.programlisting]
 ....
 # Export src and ports to client01 and client02, but only
 # client01 has root privileges on it
 /usr/src /usr/ports -maproot=root    client01
 /usr/src /usr/ports               client02
 # The client machines have root and can mount anywhere
 # on /exports. Anyone in the world can mount /exports/obj read-only
 /exports -alldirs -maproot=root      client01 client02
 /exports/obj -ro
 ....
 
 To enable the processes required by the NFS server at boot time, add these options to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 rpcbind_enable="YES"
 nfs_server_enable="YES"
 mountd_enable="YES"
 ....
 
 The server can be started now by running this command:
 
 [source,shell]
 ....
 # service nfsd start
 ....
 
 Whenever the NFS server is started, mountd also starts automatically.
 However, mountd only reads [.filename]#/etc/exports# when it is started.
 To make subsequent [.filename]#/etc/exports# edits take effect immediately, force mountd to reread it:
 
 [source,shell]
 ....
 # service mountd reload
 ....
 
 
 === Configuring the Client
 
 To enable NFS clients, set this option in each client's [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 nfs_client_enable="YES"
 ....
 
 Then, run this command on each NFS client:
 
 [source,shell]
 ....
 # service nfsclient start
 ....
 
 The client now has everything it needs to mount a remote file system.
 In these examples, the server's name is `server` and the client's name is `client`.
 To mount [.filename]#/home# on `server` to the [.filename]#/mnt# mount point on `client`:
 
 [source,shell]
 ....
 # mount server:/home /mnt
 ....
 
 The files and directories in [.filename]#/home# will now be available on `client`, in the [.filename]#/mnt# directory.
 
 To mount a remote file system each time the client boots, add it to [.filename]#/etc/fstab#:
 
 [.programlisting]
 ....
 server:/home	/mnt	nfs	rw	0	0
 ....
 
 Refer to man:fstab[5] for a description of all available options.
 
 === Locking
 
 Some applications require file locking to operate correctly.
 To enable locking, add these lines to [.filename]#/etc/rc.conf# on both the client and server:
 
 [.programlisting]
 ....
 rpc_lockd_enable="YES"
 rpc_statd_enable="YES"
 ....
 
 Then start the applications:
 
 [source,shell]
 ....
 # service lockd start
 # service statd start
 ....
 
 If locking is not required on the server, the NFS client can be configured to lock locally by including `-L` when running mount.
 Refer to man:mount_nfs[8] for further details.
 
 [[network-autofs]]
 === Automating Mounts with man:autofs[5]
 
 [NOTE]
 ====
 The man:autofs[5] automount facility is supported starting with FreeBSD 10.1-RELEASE.
 To use the automounter functionality in older versions of FreeBSD, use man:amd[8] instead.
 This chapter only describes the man:autofs[5] automounter.
 ====
 
 The man:autofs[5] facility is a common name for several components that, together, allow for automatic mounting of remote and local filesystems whenever a file or directory within that file system is accessed.
 It consists of the kernel component, man:autofs[5], and several userspace applications: man:automount[8], man:automountd[8] and man:autounmountd[8].
 It serves as an alternative for man:amd[8] from previous FreeBSD releases.
 Amd is still provided for backward compatibility purposes, as the two use different map format; the one used by autofs is the same as with other SVR4 automounters, such as the ones in Solaris, MacOS X, and Linux.
 
 The man:autofs[5] virtual filesystem is mounted on specified mountpoints by man:automount[8], usually invoked during boot.
 
 Whenever a process attempts to access file within the man:autofs[5] mountpoint, the kernel will notify man:automountd[8] daemon and pause the triggering process. The man:automountd[8] daemon will handle kernel requests by finding the proper map and mounting the filesystem according to it, then signal the kernel to release blocked process. The man:autounmountd[8] daemon automatically unmounts automounted filesystems after some time, unless they are still being used.
 
 The primary autofs configuration file is [.filename]#/etc/auto_master#. It assigns individual maps to top-level mounts.
 For an explanation of [.filename]#auto_master# and the map syntax, refer to man:auto_master[5].
 
 There is a special automounter map mounted on [.filename]#/net#.
 When a file is accessed within this directory, man:autofs[5] looks up the corresponding remote mount and automatically mounts it.
 For instance, an attempt to access a file within [.filename]#/net/foobar/usr# would tell man:automountd[8] to mount the [.filename]#/usr# export from the host `foobar`.
 
 .Mounting an Export with man:autofs[5]
 [example]
 ====
 In this example, `showmount -e` shows the exported file systems that can be mounted from the NFS server, `foobar`:
 
 [source,shell]
 ....
 % showmount -e foobar
 Exports list on foobar:
 /usr                               10.10.10.0
 /a                                 10.10.10.0
 % cd /net/foobar/usr
 ....
 
 ====
 
 The output from `showmount` shows [.filename]#/usr# as an export.
 When changing directories to [.filename]#/host/foobar/usr#, man:automountd[8] intercepts the request and attempts to resolve the hostname `foobar`.
 If successful, man:automountd[8] automatically mounts the source export.
 
 To enable man:autofs[5] at boot time, add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 autofs_enable="YES"
 ....
 
 Then man:autofs[5] can be started by running:
 
 [source,shell]
 ....
 # service automount start
 # service automountd start
 # service autounmountd start
 ....
 
 The man:autofs[5] map format is the same as in other operating systems.
 Information about this format from other sources can be useful, like the http://web.archive.org/web/20160813071113/http://images.apple.com/business/docs/Autofs.pdf[Mac OS X document].
 
 Consult the man:automount[8], man:automountd[8], man:autounmountd[8], and man:auto_master[5] manual pages for more information.
 
 [[network-nis]]
 == Network Information System (NIS)
 
 Network Information System (NIS) is designed to centralize administration of UNIX(R)-like systems such as Solaris(TM), HP-UX, AIX(R), Linux, NetBSD, OpenBSD, and FreeBSD.
 NIS was originally known as Yellow Pages but the name was changed due to trademark issues.
 This is the reason why NIS commands begin with `yp`.
 
 NIS is a Remote Procedure Call (RPC)-based client/server system that allows a group of machines within an NIS domain to share a common set of configuration files.
 This permits a system administrator to set up NIS client systems with only minimal configuration data and to add, remove, or modify configuration data from a single location.
 
 FreeBSD uses version 2 of the NIS protocol.
 
 === NIS Terms and Processes
 
 Table 28.1 summarizes the terms and important processes used by NIS:
 
 .NIS Terminology
 [cols="1,1", frame="none", options="header"]
 |===
 | Term
 | Description
 
 |NIS domain name
 |NIS servers and clients share an NIS domain name. Typically, this name does not have anything to do with DNS.
 
 |man:rpcbind[8]
 |This service enables RPC and must be running in order to run an NIS server or act as an NIS client.
 
 |man:ypbind[8]
 |This service binds an NIS client to its NIS server. It will take the NIS domain name and use RPC to connect to the server. It is the core of client/server communication in an NIS environment. If this service is not running on a client machine, it will not be able to access the NIS server.
 
 |man:ypserv[8]
 |This is the process for the NIS server. If this service stops running, the server will no longer be able to respond to NIS requests so hopefully, there is a slave server to take over. Some non-FreeBSD clients will not try to reconnect using a slave server and the ypbind process may need to be restarted on these clients.
 
 |man:rpc.yppasswdd[8]
 |This process only runs on NIS master servers. This daemon allows NIS clients to change their NIS passwords. If this daemon is not running, users will have to login to the NIS master server and change their passwords there.
 |===
 
 === Machine Types
 
 There are three types of hosts in an NIS environment:
 
 * NIS master server
-+ 
++
 This server acts as a central repository for host configuration information and maintains the authoritative copy of the files used by all of the NIS clients. 
 The [.filename]#passwd#, [.filename]#group#, and other various files used by NIS clients are stored on the master server.
 While it is possible for one machine to be an NIS master server for more than one NIS domain, this type of configuration will not be covered in this chapter as it assumes a relatively small-scale NIS environment.
 * NIS slave servers
-+ 
++
 NIS slave servers maintain copies of the NIS master's data files in order to provide redundancy.
 Slave servers also help to balance the load of the master server as NIS clients always attach to the NIS server which responds first.
 * NIS clients
-+ 
++
 NIS clients authenticate against the NIS server during log on.
 
 Information in many files can be shared using NIS.
 The [.filename]#master.passwd#, [.filename]#group#, and [.filename]#hosts# files are commonly shared via NIS.
 Whenever a process on a client needs information that would normally be found in these files locally, it makes a query to the NIS server that it is bound to instead.
 
 === Planning Considerations
 
 This section describes a sample NIS environment which consists of 15 FreeBSD machines with no centralized point of administration.
 Each machine has its own [.filename]#/etc/passwd# and [.filename]#/etc/master.passwd#.
 These files are kept in sync with each other only through manual intervention.
 Currently, when a user is added to the lab, the process must be repeated on all 15 machines.
 
 The configuration of the lab will be as follows:
 
 [.informaltable]
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Machine name
 | IP address
 | Machine role
 
 
 |`ellington`
 |`10.0.0.2`
 |NIS master
 
 |`coltrane`
 |`10.0.0.3`
 |NIS slave
 
 |`basie`
 |`10.0.0.4`
 |Faculty workstation
 
 |`bird`
 |`10.0.0.5`
 |Client machine
 
 |`cli[1-11]`
 |`10.0.0.[6-17]`
 |Other client machines
 |===
 
 If this is the first time an NIS scheme is being developed, it should be thoroughly planned ahead of time.
 Regardless of network size, several decisions need to be made as part of the planning process.
 
 ==== Choosing a NIS Domain Name
 
 When a client broadcasts its requests for info, it includes the name of the NIS domain that it is part of.
 This is how multiple servers on one network can tell which server should answer which request.
 Think of the NIS domain name as the name for a group of hosts.
 
 Some organizations choose to use their Internet domain name for their NIS domain name.
 This is not recommended as it can cause confusion when trying to debug network problems.
 The NIS domain name should be unique within the network and it is helpful if it describes the group of machines it represents.
 For example, the Art department at Acme Inc. might be in the "acme-art"NIS domain.
 This example will use the domain name `test-domain`.
 
 However, some non-FreeBSD operating systems require the NIS domain name to be the same as the Internet domain name.
 If one or more machines on the network have this restriction, the Internet domain name _must_ be used as the NIS domain name.
 
 ==== Physical Server Requirements
 
 There are several things to keep in mind when choosing a machine to use as a NIS server.
 Since NIS clients depend upon the availability of the server, choose a machine that is not rebooted frequently.
 The NIS server should ideally be a stand alone machine whose sole purpose is to be an NIS server.
 If the network is not heavily used, it is acceptable to put the NIS server on a machine running other services.
 However, if the NIS server becomes unavailable, it will adversely affect all NIS clients.
 
 === Configuring the NIS Master Server
 
 The canonical copies of all NIS files are stored on the master server.
 The databases used to store the information are called NIS maps.
 In FreeBSD, these maps are stored in [.filename]#/var/yp/[domainname]# where [.filename]#[domainname]# is the name of the NIS domain.
 Since multiple domains are supported, it is possible to have several directories, one for each domain.
 Each domain will have its own independent set of maps.
 
 NIS master and slave servers handle all NIS requests through man:ypserv[8].
 This daemon is responsible for receiving incoming requests from NIS clients, translating the requested domain and map name to a path to the corresponding database file, and transmitting data from the database back to the client.
 
 Setting up a master NIS server can be relatively straight forward, depending on environmental needs.
 Since FreeBSD provides built-in NIS support, it only needs to be enabled by adding the following lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 nisdomainname="test-domain"	<.>
 nis_server_enable="YES"		<.>
 nis_yppasswdd_enable="YES"	<.>
 ....
 
 <.> This line sets the NIS domain name to `test-domain`.
 <.> This automates the start up of the NIS server processes when the system boots.
 <.> This enables the man:rpc.yppasswdd[8] daemon so that users can change their NIS password from a client machine.
 
 Care must be taken in a multi-server domain where the server machines are also NIS clients.
 It is generally a good idea to force the servers to bind to themselves rather than allowing them to broadcast bind requests and possibly become bound to each other.
 Strange failure modes can result if one server goes down and others are dependent upon it.
 Eventually, all the clients will time out and attempt to bind to other servers, but the delay involved can be considerable and the failure mode is still present since the servers might bind to each other all over again.
 
 A server that is also a client can be forced to bind to a particular server by adding these additional lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 nis_client_enable="YES"				<.>
 nis_client_flags="-S test-domain,server"	<.>
 ....
 
 <.> This enables running client stuff as well.
 <.> This line sets the NIS domain name to `test-domain` and bind to itself.
 
 After saving the edits, type `/etc/netstart` to restart the network and apply the values defined in [.filename]#/etc/rc.conf#.
 Before initializing the NIS maps, start man:ypserv[8]:
 
 [source,shell]
 ....
 # service ypserv start
 ....
 
 
 ==== Initializing the NIS Maps
 
 NIS maps are generated from the configuration files in [.filename]#/etc# on the NIS master, with one exception: [.filename]#/etc/master.passwd#.
 This is to prevent the propagation of passwords to all the servers in the NIS domain.
 Therefore, before the NIS maps are initialized, configure the primary password files:
 
 [source,shell]
 ....
 # cp /etc/master.passwd /var/yp/master.passwd
 # cd /var/yp
 # vi master.passwd
 ....
 
 It is advisable to remove all entries for system accounts as well as any user accounts that do not need to be propagated to the NIS clients, such as the `root` and any other administrative accounts.
 
 [NOTE]
 ====
 Ensure that the [.filename]#/var/yp/master.passwd# is neither group or world readable by setting its permissions to `600`.
 ====
 
 After completing this task, initialize the NIS maps.
 FreeBSD includes the man:ypinit[8] script to do this.
 When generating maps for the master server, include `-m` and specify the NIS domain name:
 
 [source,shell]
 ....
 ellington# ypinit -m test-domain
 Server Type: MASTER Domain: test-domain
 Creating an YP server will require that you answer a few questions.
 Questions will all be asked at the beginning of the procedure.
 Do you want this procedure to quit on non-fatal errors? [y/n: n] n
 Ok, please remember to go back and redo manually whatever fails.
 If not, something might not work.
 At this point, we have to construct a list of this domains YP servers.
 rod.darktech.org is already known as master server.
 Please continue to add any slave servers, one per line. When you are
 done with the list, type a <control D>.
 master server   :  ellington
 next host to add:  coltrane
 next host to add:  ^D
 The current list of NIS servers looks like this:
 ellington
 coltrane
 Is this correct?  [y/n: y] y
 
 [..output from map generation..]
 
 NIS Map update completed.
 ellington has been setup as an YP master server without any errors.
 ....
 
 This will create [.filename]#/var/yp/Makefile# from [.filename]#/var/yp/Makefile.dist#.
 By default, this file assumes that the environment has a single NIS server with only FreeBSD clients.
 Since `test-domain` has a slave server, edit this line in [.filename]#/var/yp/Makefile# so that it begins with a comment (`#`):
 
 [.programlisting]
 ....
 NOPUSH = "True"
 ....
 
 
 ==== Adding New Users
 
 Every time a new user is created, the user account must be added to the master NIS server and the NIS maps rebuilt.
 Until this occurs, the new user will not be able to login anywhere except on the NIS master.
 For example, to add the new user `jsmith` to the `test-domain` domain, run these commands on the master server:
 
 [source,shell]
 ....
 # pw useradd jsmith
 # cd /var/yp
 # make test-domain
 ....
 
 The user could also be added using `adduser jsmith` instead of `pw useradd smith`.
 
 === Setting up a NIS Slave Server
 
 To set up an NIS slave server, log on to the slave server and edit [.filename]#/etc/rc.conf# as for the master server.
 Do not generate any NIS maps, as these already exist on the master server.
 When running `ypinit` on the slave server, use `-s` (for slave) instead of `-m` (for master).
 This option requires the name of the NIS master in addition to the domain name, as seen in this example:
 
 [source,shell]
 ....
 coltrane# ypinit -s ellington test-domain
 
 Server Type: SLAVE Domain: test-domain Master: ellington
 
 Creating an YP server will require that you answer a few questions.
 Questions will all be asked at the beginning of the procedure.
 
 Do you want this procedure to quit on non-fatal errors? [y/n: n]  n
 
 Ok, please remember to go back and redo manually whatever fails.
 If not, something might not work.
 There will be no further questions. The remainder of the procedure
 should take a few minutes, to copy the databases from ellington.
 Transferring netgroup...
 ypxfr: Exiting: Map successfully transferred
 Transferring netgroup.byuser...
 ypxfr: Exiting: Map successfully transferred
 Transferring netgroup.byhost...
 ypxfr: Exiting: Map successfully transferred
 Transferring master.passwd.byuid...
 ypxfr: Exiting: Map successfully transferred
 Transferring passwd.byuid...
 ypxfr: Exiting: Map successfully transferred
 Transferring passwd.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring group.bygid...
 ypxfr: Exiting: Map successfully transferred
 Transferring group.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring services.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring rpc.bynumber...
 ypxfr: Exiting: Map successfully transferred
 Transferring rpc.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring protocols.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring master.passwd.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring networks.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring networks.byaddr...
 ypxfr: Exiting: Map successfully transferred
 Transferring netid.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring hosts.byaddr...
 ypxfr: Exiting: Map successfully transferred
 Transferring protocols.bynumber...
 ypxfr: Exiting: Map successfully transferred
 Transferring ypservers...
 ypxfr: Exiting: Map successfully transferred
 Transferring hosts.byname...
 ypxfr: Exiting: Map successfully transferred
 
 coltrane has been setup as an YP slave server without any errors.
 Remember to update map ypservers on ellington.
 ....
 
 This will generate a directory on the slave server called [.filename]#/var/yp/test-domain# which contains copies of the NIS master server's maps.
 Adding these [.filename]#/etc/crontab# entries on each slave server will force the slaves to sync their maps with the maps on the master server:
 
 [.programlisting]
 ....
 20      *       *       *       *       root   /usr/libexec/ypxfr passwd.byname
 21      *       *       *       *       root   /usr/libexec/ypxfr passwd.byuid
 ....
 
 These entries are not mandatory because the master server automatically attempts to push any map changes to its slaves.
 However, since clients may depend upon the slave server to provide correct password information, it is recommended to force frequent password map updates.
 This is especially important on busy networks where map updates might not always complete.
 
 To finish the configuration, run `/etc/netstart` on the slave server in order to start the NIS services.
 
 === Setting Up an NIS Client
 
 An NIS client binds to an NIS server using man:ypbind[8].
 This daemon broadcasts RPC requests on the local network.
 These requests specify the domain name configured on the client.
 If an NIS server in the same domain receives one of the broadcasts, it will respond to ypbind, which will record the server's address.
 If there are several servers available, the client will use the address of the first server to respond and will direct all of its NIS requests to that server.
 The client will automatically ping the server on a regular basis to make sure it is still available.
 If it fails to receive a reply within a reasonable amount of time, ypbind will mark the domain as unbound and begin broadcasting again in the hopes of locating another server.
 
 To configure a FreeBSD machine to be an NIS client:
 
 [.procedure]
 ====
 . Edit [.filename]#/etc/rc.conf# and add the following lines in order to set the NIS domain name and start man:ypbind[8] during network startup:
 +
 [.programlisting]
 ....
 nisdomainname="test-domain"
 nis_client_enable="YES"
 ....
 
 . To import all possible password entries from the NIS server, use `vipw` to remove all user accounts except one from [.filename]#/etc/master.passwd#. When removing the accounts, keep in mind that at least one local account should remain and this account should be a member of `wheel`. If there is a problem with NIS, this local account can be used to log in remotely, become the superuser, and fix the problem. Before saving the edits, add the following line to the end of the file:
 +
 [.programlisting]
 ....
 +:::::::::
 ....
-+ 
++
 This line configures the client to provide anyone with a valid account in the NIS server's password maps an account on the client.
 There are many ways to configure the NIS client by modifying this line.
 One method is described in <<network-netgroups>>.
 For more detailed reading, refer to the book `Managing NFS and NIS`, published by O'Reilly Media.
 . To import all possible group entries from the NIS server, add this line to [.filename]#/etc/group#:
 +
 [.programlisting]
 ....
 +:*::
 ....
 ====
 
 To start the NIS client immediately, execute the following commands as the superuser:
 
 [source,shell]
 ....
 # /etc/netstart
 # service ypbind start
 ....
 
 After completing these steps, running `ypcat passwd` on the client should show the server's [.filename]#passwd# map.
 
 === NIS Security
 
 Since RPC is a broadcast-based service, any system running ypbind within the same domain can retrieve the contents of the NIS maps.
 To prevent unauthorized transactions, man:ypserv[8] supports a feature called "securenets" which can be used to restrict access to a given set of hosts. 
 By default, this information is stored in [.filename]#/var/yp/securenets#, unless man:ypserv[8] is started with `-p` and an alternate path.
 This file contains entries that consist of a network specification and a network mask separated by white space.
 Lines starting with `#` are considered to be comments.
 A sample [.filename]#securenets# might look like this:
 
 [.programlisting]
 ....
 # allow connections from local host -- mandatory
 127.0.0.1     255.255.255.255
 # allow connections from any host
 # on the 192.168.128.0 network
 192.168.128.0 255.255.255.0
 # allow connections from any host
 # between 10.0.0.0 to 10.0.15.255
 # this includes the machines in the testlab
 10.0.0.0      255.255.240.0
 ....
 
 If man:ypserv[8] receives a request from an address that matches one of these rules, it will process the request normally.
 If the address fails to match a rule, the request will be ignored and a warning message will be logged.
 If the [.filename]#securenets# does not exist, `ypserv` will allow connections from any host.
 
 crossref:security[tcpwrappers,"TCP Wrapper"] is an alternate mechanism for providing access control instead of [.filename]#securenets#.
 While either access control mechanism adds some security, they are both vulnerable to "IP spoofing" attacks.
 All NIS-related traffic should be blocked at the firewall.
 
 Servers using [.filename]#securenets# may fail to serve legitimate NIS clients with archaic TCP/IP implementations.
 Some of these implementations set all host bits to zero when doing broadcasts or fail to observe the subnet mask when calculating the broadcast address. 
 While some of these problems can be fixed by changing the client configuration, other problems may force the retirement of these client systems or the abandonment of [.filename]#securenets#.
 
 The use of TCP Wrapper increases the latency of the NIS server.
 The additional delay may be long enough to cause timeouts in client programs, especially in busy networks with slow NIS servers.
 If one or more clients suffer from latency, convert those clients into NIS slave servers and force them to bind to themselves.
 
 ==== Barring Some Users
 
 In this example, the `basie` system is a faculty workstation within the NIS domain.
 The [.filename]#passwd# map on the master NIS server contains accounts for both faculty and students.
 This section demonstrates how to allow faculty logins on this system while refusing student logins.
 
 To prevent specified users from logging on to a system, even if they are present in the NIS database, use `vipw` to add `-_username_` with the correct number of colons towards the end of [.filename]#/etc/master.passwd# on the client, where _username_ is the username of a user to bar from logging in.
 The line with the blocked user must be before the `+` line that allows NIS users.
 In this example, `bill` is barred from logging on to `basie`:
 
 [source,shell]
 ....
 basie# cat /etc/master.passwd
 root:[password]:0:0::0:0:The super-user:/root:/bin/csh
 toor:[password]:0:0::0:0:The other super-user:/root:/bin/sh
 daemon:*:1:1::0:0:Owner of many system processes:/root:/usr/sbin/nologin
 operator:*:2:5::0:0:System &:/:/usr/sbin/nologin
 bin:*:3:7::0:0:Binaries Commands and Source,,,:/:/usr/sbin/nologin
 tty:*:4:65533::0:0:Tty Sandbox:/:/usr/sbin/nologin
 kmem:*:5:65533::0:0:KMem Sandbox:/:/usr/sbin/nologin
 games:*:7:13::0:0:Games pseudo-user:/usr/games:/usr/sbin/nologin
 news:*:8:8::0:0:News Subsystem:/:/usr/sbin/nologin
 man:*:9:9::0:0:Mister Man Pages:/usr/share/man:/usr/sbin/nologin
 bind:*:53:53::0:0:Bind Sandbox:/:/usr/sbin/nologin
 uucp:*:66:66::0:0:UUCP pseudo-user:/var/spool/uucppublic:/usr/libexec/uucp/uucico
 xten:*:67:67::0:0:X-10 daemon:/usr/local/xten:/usr/sbin/nologin
 pop:*:68:6::0:0:Post Office Owner:/nonexistent:/usr/sbin/nologin
 nobody:*:65534:65534::0:0:Unprivileged user:/nonexistent:/usr/sbin/nologin
 -bill:::::::::
 +:::::::::
 
 basie#
 ....
 
 
 [[network-netgroups]]
 === Using Netgroups
 
 Barring specified users from logging on to individual systems becomes unscaleable on larger networks and quickly loses the main benefit of NIS: _centralized_ administration.
 
 Netgroups were developed to handle large, complex networks with hundreds of users and machines.
 Their use is comparable to UNIX(R) groups, where the main difference is the lack of a numeric ID and the ability to define a netgroup by including both user accounts and other netgroups.
 
 To expand on the example used in this chapter, the NIS domain will be extended to add the users and systems shown in Tables 28.2 and 28.3:
 
 .Additional Users
 [cols="1,1", frame="none", options="header"]
 |===
 | User Name(s)
 | Description
 
 |`alpha`, `beta`
 |IT department employees
 
 |`charlie`, `delta`
 |IT department apprentices
 
 |`echo`, `foxtrott`, `golf`, ...
 |employees
 
 |`able`, `baker`, ...
 |interns
 |===
 
 .Additional Systems
 [cols="1,1", frame="none", options="header"]
 |===
 | Machine Name(s)
 | Description
 
 |`war`, `death`, `famine`, `pollution`
 |Only IT employees are allowed to log onto these servers.
 
 |`pride`, `greed`, `envy`, `wrath`, `lust`, `sloth`
 |All members of the IT department are allowed to login onto these servers.
 
 |`one`, `two`, `three`, `four`, ...
 |Ordinary workstations used by employees.
 
 |`trashcan`
 |A very old machine without any critical data. Even interns are allowed to use this system.
 |===
 
 When using netgroups to configure this scenario, each user is assigned to one or more netgroups and logins are then allowed or forbidden for all members of the netgroup.
 When adding a new machine, login restrictions must be defined for all netgroups.
 When a new user is added, the account must be added to one or more netgroups.
 If the NIS setup is planned carefully, only one central configuration file needs modification to grant or deny access to machines.
 
 The first step is the initialization of the NIS`netgroup` map.
 In FreeBSD, this map is not created by default.
 On the NIS master server, use an editor to create a map named [.filename]#/var/yp/netgroup#.
 
 This example creates four netgroups to represent IT employees, IT apprentices, employees, and interns:
 
 [.programlisting]
 ....
 IT_EMP  (,alpha,test-domain)    (,beta,test-domain)
 IT_APP  (,charlie,test-domain)  (,delta,test-domain)
 USERS   (,echo,test-domain)     (,foxtrott,test-domain) \
         (,golf,test-domain)
 INTERNS (,able,test-domain)     (,baker,test-domain)
 ....
 
 Each entry configures a netgroup. The first column in an entry is the name of the netgroup.
 Each set of brackets represents either a group of one or more users or the name of another netgroup.
 When specifying a user, the three comma-delimited fields inside each group represent:
 
 . The name of the host(s) where the other fields representing the user are valid. If a hostname is not specified, the entry is valid on all hosts.
 . The name of the account that belongs to this netgroup.
 . The NIS domain for the account. Accounts may be imported from other NIS domains into a netgroup.
 
 If a group contains multiple users, separate each user with whitespace.
 Additionally, each field may contain wildcards.
 See man:netgroup[5] for details.
 
 Netgroup names longer than 8 characters should not be used.
 The names are case sensitive and using capital letters for netgroup names is an easy way to distinguish between user, machine and netgroup names.
 
 Some non-FreeBSD NIS clients cannot handle netgroups containing more than 15 entries.
 This limit may be circumvented by creating several sub-netgroups with 15 users or fewer and a real netgroup consisting of the sub-netgroups, as seen in this example:
 
 [.programlisting]
 ....
 BIGGRP1  (,joe1,domain)  (,joe2,domain)  (,joe3,domain) [...]
 BIGGRP2  (,joe16,domain)  (,joe17,domain) [...]
 BIGGRP3  (,joe31,domain)  (,joe32,domain)
 BIGGROUP  BIGGRP1 BIGGRP2 BIGGRP3
 ....
 
 Repeat this process if more than 225 (15 times 15) users exist within a single netgroup.
 
 To activate and distribute the new NIS map:
 
 [source,shell]
 ....
 ellington# cd /var/yp
 ellington# make
 ....
 
 This will generate the three NIS maps [.filename]#netgroup#, [.filename]#netgroup.byhost# and [.filename]#netgroup.byuser#.
 Use the map key option of man:ypcat[1] to check if the new NIS maps are available:
 
 [source,shell]
 ....
 ellington% ypcat -k netgroup
 ellington% ypcat -k netgroup.byhost
 ellington% ypcat -k netgroup.byuser
 ....
 
 The output of the first command should resemble the contents of [.filename]#/var/yp/netgroup#.
 The second command only produces output if host-specific netgroups were created.
 The third command is used to get the list of netgroups for a user.
 
 To configure a client, use man:vipw[8] to specify the name of the netgroup.
 For example, on the server named `war`, replace this line:
 
 [.programlisting]
 ....
 +:::::::::
 ....
 
 with
 
 [.programlisting]
 ....
 +@IT_EMP:::::::::
 ....
 
 This specifies that only the users defined in the netgroup `IT_EMP` will be imported into this system's password database and only those users are allowed to login to this system.
 
 This configuration also applies to the `~` function of the shell and all routines which convert between user names and numerical user IDs.
 In other words, `cd ~_user_` will not work, `ls -l` will show the numerical ID instead of the username, and `find . -user joe -print` will fail with the message `No such user`.
 To fix this, import all user entries without allowing them to login into the servers.
 This can be achieved by adding an extra line:
 
 [.programlisting]
 ....
 +:::::::::/usr/sbin/nologin
 ....
 
 This line configures the client to import all entries but to replace the shell in those entries with [.filename]#/usr/sbin/nologin#.
 
 Make sure that extra line is placed _after_ `+@IT_EMP:::::::::`.
 Otherwise, all user accounts imported from NIS will have [.filename]#/usr/sbin/nologin# as their login shell and no one will be able to login to the system.
 
 To configure the less important servers, replace the old `+:::::::::` on the servers with these lines:
 
 [.programlisting]
 ....
 +@IT_EMP:::::::::
 +@IT_APP:::::::::
 +:::::::::/usr/sbin/nologin
 ....
 
 The corresponding lines for the workstations would be:
 
 [.programlisting]
 ....
 +@IT_EMP:::::::::
 +@USERS:::::::::
 +:::::::::/usr/sbin/nologin
 ....
 
 NIS supports the creation of netgroups from other netgroups which can be useful if the policy regarding user access changes.
 One possibility is the creation of role-based netgroups.
 For example, one might create a netgroup called `BIGSRV` to define the login restrictions for the important servers, another netgroup called `SMALLSRV` for the less important servers, and a third netgroup called `USERBOX` for the workstations.
 Each of these netgroups contains the netgroups that are allowed to login onto these machines.
 The new entries for the NIS`netgroup` map would look like this:
 
 [.programlisting]
 ....
 BIGSRV    IT_EMP  IT_APP
 SMALLSRV  IT_EMP  IT_APP  ITINTERN
 USERBOX   IT_EMP  ITINTERN USERS
 ....
 
 This method of defining login restrictions works reasonably well when it is possible to define groups of machines with identical restrictions.
 Unfortunately, this is the exception and not the rule.
 Most of the time, the ability to define login restrictions on a per-machine basis is required.
 
 Machine-specific netgroup definitions are another possibility to deal with the policy changes.
 In this scenario, the [.filename]#/etc/master.passwd# of each system contains two lines starting with "+".
 The first line adds a netgroup with the accounts allowed to login onto this machine and the second line adds all other accounts with [.filename]#/usr/sbin/nologin# as shell.
 It is recommended to use the "ALL-CAPS" version of the hostname as the name of the netgroup:
 
 [.programlisting]
 ....
 +@BOXNAME:::::::::
 +:::::::::/usr/sbin/nologin
 ....
 
 Once this task is completed on all the machines, there is no longer a need to modify the local versions of [.filename]#/etc/master.passwd# ever again.
 All further changes can be handled by modifying the NIS map.
 Here is an example of a possible `netgroup` map for this scenario:
 
 [.programlisting]
 ....
 # Define groups of users first
 IT_EMP    (,alpha,test-domain)    (,beta,test-domain)
 IT_APP    (,charlie,test-domain)  (,delta,test-domain)
 DEPT1     (,echo,test-domain)     (,foxtrott,test-domain)
 DEPT2     (,golf,test-domain)     (,hotel,test-domain)
 DEPT3     (,india,test-domain)    (,juliet,test-domain)
 ITINTERN  (,kilo,test-domain)     (,lima,test-domain)
 D_INTERNS (,able,test-domain)     (,baker,test-domain)
 #
 # Now, define some groups based on roles
 USERS     DEPT1   DEPT2     DEPT3
 BIGSRV    IT_EMP  IT_APP
 SMALLSRV  IT_EMP  IT_APP    ITINTERN
 USERBOX   IT_EMP  ITINTERN  USERS
 #
 # And a groups for a special tasks
 # Allow echo and golf to access our anti-virus-machine
 SECURITY  IT_EMP  (,echo,test-domain)  (,golf,test-domain)
 #
 # machine-based netgroups
 # Our main servers
 WAR       BIGSRV
 FAMINE    BIGSRV
 # User india needs access to this server
 POLLUTION  BIGSRV  (,india,test-domain)
 #
 # This one is really important and needs more access restrictions
 DEATH     IT_EMP
 #
 # The anti-virus-machine mentioned above
 ONE       SECURITY
 #
 # Restrict a machine to a single user
 TWO       (,hotel,test-domain)
 # [...more groups to follow]
 ....
 
 It may not always be advisable to use machine-based netgroups.
 When deploying a couple of dozen or hundreds of systems, role-based netgroups instead of machine-based netgroups may be used to keep the size of the NIS map within reasonable limits.
 
 === Password Formats
 
 NIS requires that all hosts within an NIS domain use the same format for encrypting passwords.
 If users have trouble authenticating on an NIS client, it may be due to a differing password format.
 In a heterogeneous network, the format must be supported by all operating systems, where DES is the lowest common standard.
 
 To check which format a server or client is using, look at this section of [.filename]#/etc/login.conf#:
 
 [.programlisting]
 ....
 default:\
 	:passwd_format=des:\
 	:copyright=/etc/COPYRIGHT:\
 	[Further entries elided]
 ....
 
 In this example, the system is using the DES format.
 Other possible values are `blf` for Blowfish and `md5` for MD5 encrypted passwords.
 
 If the format on a host needs to be edited to match the one being used in the NIS domain, the login capability database must be rebuilt after saving the change:
 
 [source,shell]
 ....
 # cap_mkdb /etc/login.conf
 ....
 
 [NOTE]
 ====
 The format of passwords for existing user accounts will not be updated until each user changes their password _after_ the login capability database is rebuilt.
 ====
 
 [[network-ldap]]
 == Lightweight Directory Access Protocol (LDAP)
 
 The Lightweight Directory Access Protocol (LDAP) is an application layer protocol used to access, modify, and authenticate objects using a distributed directory information service.
 Think of it as a phone or record book which stores several levels of hierarchical, homogeneous information.
 It is used in Active Directory and OpenLDAP networks and allows users to access to several levels of internal information utilizing a single account.
 For example, email authentication, pulling employee contact information, and internal website authentication might all make use of a single user account in the LDAP server's record base.
 
 This section provides a quick start guide for configuring an LDAP server on a FreeBSD system.
 It assumes that the administrator already has a design plan which includes the type of information to store, what that information will be used for, which users should have access to that information, and how to secure this information from unauthorized access.
 
 === LDAP Terminology and Structure
 
 LDAP uses several terms which should be understood before starting the configuration.
 All directory entries consist of a group of _attributes_.
 Each of these attribute sets contains a unique identifier known as a _Distinguished Name_ (DN) which is normally built from several other attributes such as the common or _Relative Distinguished Name_ (RDN).
 Similar to how directories have absolute and relative paths, consider a DN as an absolute path and the RDN as the relative path.
 
 An example LDAP entry looks like the following.
 This example searches for the entry for the specified user account (`uid`), organizational unit (`ou`), and organization (`o`):
 
 [source,shell]
 ....
 % ldapsearch -xb "uid=trhodes,ou=users,o=example.com"
 # extended LDIF
 #
 # LDAPv3
 # base <uid=trhodes,ou=users,o=example.com> with scope subtree
 # filter: (objectclass=*)
 # requesting: ALL
 #
 
 # trhodes, users, example.com
 dn: uid=trhodes,ou=users,o=example.com
 mail: trhodes@example.com
 cn: Tom Rhodes
 uid: trhodes
 telephoneNumber: (123) 456-7890
 
 # search result
 search: 2
 result: 0 Success
 
 # numResponses: 2
 # numEntries: 1
 ....
 
 This example entry shows the values for the `dn`, `mail`, `cn`, `uid`, and `telephoneNumber` attributes.
 The cn attribute is the RDN.
 
 More information about LDAP and its terminology can be found at http://www.openldap.org/doc/admin24/intro.html[http://www.openldap.org/doc/admin24/intro.html].
 
 [[ldap-config]]
 === Configuring an LDAP Server
 
 FreeBSD does not provide a built-in LDAP server.
 Begin the configuration by installing package:net/openldap-server[] package or port:
 
 [source,shell]
 ....
 # pkg install openldap-server
 ....
 
 There is a large set of default options enabled in the link:{linux-users}#software[package].
 Review them by running `pkg info openldap-server`.
 If they are not sufficient (for example if SQL support is needed), please consider recompiling the port using the appropriate crossref:ports[ports-using,framework].
 
 The installation creates the directory [.filename]#/var/db/openldap-data# to hold the data.
 The directory to store the certificates must be created:
 
 [source,shell]
 ....
 # mkdir /usr/local/etc/openldap/private
 ....
 
 The next phase is to configure the Certificate Authority.
 The following commands must be executed from [.filename]#/usr/local/etc/openldap/private#.
 This is important as the file permissions need to be restrictive and users should not have access to these files.
 More detailed information about certificates and their parameters can be found in crossref:security[openssl,"OpenSSL"].
 To create the Certificate Authority, start with this command and follow the prompts:
 
 [source,shell]
 ....
 # openssl req -days 365 -nodes -new -x509 -keyout ca.key -out ../ca.crt
 ....
 
 The entries for the prompts may be generic _except_ for the `Common Name`.
 This entry must be _different_ than the system hostname.
 If this will be a self signed certificate, prefix the hostname with `CA` for Certificate Authority.
 
 The next task is to create a certificate signing request and a private key.
 Input this command and follow the prompts:
 
 [source,shell]
 ....
 # openssl req -days 365 -nodes -new -keyout server.key -out server.csr
 ....
 
 During the certificate generation process, be sure to correctly set the `Common Name` attribute.
 The Certificate Signing Request must be signed with the Certificate Authority in order to be used as a valid certificate:
 
 [source,shell]
 ....
 # openssl x509 -req -days 365 -in server.csr -out ../server.crt -CA ../ca.crt -CAkey ca.key -CAcreateserial
 ....
 
 The final part of the certificate generation process is to generate and sign the client certificates:
 
 [source,shell]
 ....
 # openssl req -days 365 -nodes -new -keyout client.key -out client.csr
 # openssl x509 -req -days 3650 -in client.csr -out ../client.crt -CA ../ca.crt -CAkey ca.key
 ....
 
 Remember to use the same `Common Name` attribute when prompted.
 When finished, ensure that a total of eight (8) new files have been generated through the proceeding commands.
 
 The daemon running the OpenLDAP server is [.filename]#slapd#.
 Its configuration is performed through [.filename]#slapd.ldif#: the old [.filename]#slapd.conf# has been deprecated by OpenLDAP.
 
 http://www.openldap.org/doc/admin24/slapdconf2.html[Configuration examples] for [.filename]#slapd.ldif# are available and can also be found in [.filename]#/usr/local/etc/openldap/slapd.ldif.sample#.
 Options are documented in slapd-config(5).
 Each section of [.filename]#slapd.ldif#, like all the other LDAP attribute sets, is uniquely identified through a DN.
 Be sure that no blank lines are left between the `dn:` statement and the desired end of the section.
 In the following example, TLS will be used to implement a secure channel.
 The first section represents the global configuration:
 
 [.programlisting]
 ....
 #
 # See slapd-config(5) for details on configuration options.
 # This file should NOT be world readable.
 #
 dn: cn=config
 objectClass: olcGlobal
 cn: config
 #
 #
 # Define global ACLs to disable default read access.
 #
 olcArgsFile: /var/run/openldap/slapd.args
 olcPidFile: /var/run/openldap/slapd.pid
 olcTLSCertificateFile: /usr/local/etc/openldap/server.crt
 olcTLSCertificateKeyFile: /usr/local/etc/openldap/private/server.key
 olcTLSCACertificateFile: /usr/local/etc/openldap/ca.crt
 #olcTLSCipherSuite: HIGH
 olcTLSProtocolMin: 3.1
 olcTLSVerifyClient: never
 ....
 
 The Certificate Authority, server certificate and server private key files must be specified here.
 It is recommended to let the clients choose the security cipher and omit option `olcTLSCipherSuite` (incompatible with TLS clients other than [.filename]#openssl#). Option `olcTLSProtocolMin` lets the server require a minimum security level: it is recommended.
 While verification is mandatory for the server, it is not for the client: `olcTLSVerifyClient: never`.
 
 The second section is about the backend modules and can be configured as follows:
 
 [.programlisting]
 ....
 #
 # Load dynamic backend modules:
 #
 dn: cn=module,cn=config
 objectClass: olcModuleList
 cn: module
 olcModulepath:	/usr/local/libexec/openldap
 olcModuleload:	back_mdb.la
 #olcModuleload:	back_bdb.la
 #olcModuleload:	back_hdb.la
 #olcModuleload:	back_ldap.la
 #olcModuleload:	back_passwd.la
 #olcModuleload:	back_shell.la
 ....
 
 The third section is devoted to load the needed `ldif` schemas to be used by the databases: they are essential.
 
 [.programlisting]
 ....
 dn: cn=schema,cn=config
 objectClass: olcSchemaConfig
 cn: schema
 
 include: file:///usr/local/etc/openldap/schema/core.ldif
 include: file:///usr/local/etc/openldap/schema/cosine.ldif
 include: file:///usr/local/etc/openldap/schema/inetorgperson.ldif
 include: file:///usr/local/etc/openldap/schema/nis.ldif
 ....
 
 Next, the frontend configuration section:
 
 [.programlisting]
 ....
 # Frontend settings
 #
 dn: olcDatabase={-1}frontend,cn=config
 objectClass: olcDatabaseConfig
 objectClass: olcFrontendConfig
 olcDatabase: {-1}frontend
 olcAccess: to * by * read
 #
 # Sample global access control policy:
 #	Root DSE: allow anyone to read it
 #	Subschema (sub)entry DSE: allow anyone to read it
 #	Other DSEs:
 #		Allow self write access
 #		Allow authenticated users read access
 #		Allow anonymous users to authenticate
 #
 #olcAccess: to dn.base="" by * read
 #olcAccess: to dn.base="cn=Subschema" by * read
 #olcAccess: to *
 #	by self write
 #	by users read
 #	by anonymous auth
 #
 # if no access controls are present, the default policy
 # allows anyone and everyone to read anything but restricts
 # updates to rootdn.  (e.g., "access to * by * read")
 #
 # rootdn can always read and write EVERYTHING!
 #
 olcPasswordHash: {SSHA}
 # {SSHA} is already the default for olcPasswordHash
 ....
 
 Another section is devoted to the _configuration backend_, the only way to later access the OpenLDAP server configuration is as a global super-user.
 
 [.programlisting]
 ....
 dn: olcDatabase={0}config,cn=config
 objectClass: olcDatabaseConfig
 olcDatabase: {0}config
 olcAccess: to * by * none
 olcRootPW: {SSHA}iae+lrQZILpiUdf16Z9KmDmSwT77Dj4U
 ....
 
 The default administrator username is `cn=config`.
 Type [.filename]#slappasswd# in a shell, choose a password and use its hash in `olcRootPW`.
 If this option is not specified now, before [.filename]#slapd.ldif# is imported, no one will be later able to modify the _global configuration_ section.
 
 The last section is about the database backend:
 
 [.programlisting]
 ....
 #######################################################################
 # LMDB database definitions
 #######################################################################
 #
 dn: olcDatabase=mdb,cn=config
 objectClass: olcDatabaseConfig
 objectClass: olcMdbConfig
 olcDatabase: mdb
 olcDbMaxSize: 1073741824
 olcSuffix: dc=domain,dc=example
 olcRootDN: cn=mdbadmin,dc=domain,dc=example
 # Cleartext passwords, especially for the rootdn, should
 # be avoided.  See slappasswd(8) and slapd-config(5) for details.
 # Use of strong authentication encouraged.
 olcRootPW: {SSHA}X2wHvIWDk6G76CQyCMS1vDCvtICWgn0+
 # The database directory MUST exist prior to running slapd AND
 # should only be accessible by the slapd and slap tools.
 # Mode 700 recommended.
 olcDbDirectory:	/var/db/openldap-data
 # Indices to maintain
 olcDbIndex: objectClass eq
 ....
 
 This database hosts the _actual contents_ of the LDAP directory.
 Types other than `mdb` are available.
 Its super-user, not to be confused with the global one, is configured here: a (possibly custom) username in `olcRootDN` and the password hash in `olcRootPW`; [.filename]#slappasswd# can be used as before.
 
 This http://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=tree;f=tests/data/regressions/its8444;h=8a5e808e63b0de3d2bdaf2cf34fecca8577ca7fd;hb=HEAD[repository] contains four examples of [.filename]#slapd.ldif#.
 To convert an existing [.filename]#slapd.conf# into [.filename]#slapd.ldif#, refer to http://www.openldap.org/doc/admin24/slapdconf2.html[this page] (please note that this may introduce some unuseful options).
 
 When the configuration is completed, [.filename]#slapd.ldif# must be placed in an empty directory.
 It is recommended to create it as:
 
 [source,shell]
 ....
 # mkdir /usr/local/etc/openldap/slapd.d/
 ....
 
 Import the configuration database:
 
 [source,shell]
 ....
 # /usr/local/sbin/slapadd -n0 -F /usr/local/etc/openldap/slapd.d/ -l /usr/local/etc/openldap/slapd.ldif
 ....
 
 Start the [.filename]#slapd# daemon:
 
 [source,shell]
 ....
 # /usr/local/libexec/slapd -F /usr/local/etc/openldap/slapd.d/
 ....
 
 Option `-d` can be used for debugging, as specified in slapd(8).
 To verify that the server is running and working:
 
 [source,shell]
 ....
 # ldapsearch -x -b '' -s base '(objectclass=*)' namingContexts
 # extended LDIF
 #
 # LDAPv3
 # base <> with scope baseObject
 # filter: (objectclass=*)
 # requesting: namingContexts
 #
 
 #
 dn:
 namingContexts: dc=domain,dc=example
 
 # search result
 search: 2
 result: 0 Success
 
 # numResponses: 2
 # numEntries: 1
 ....
 
 The server must still be trusted.
 If that has never been done before, follow these instructions.
 Install the OpenSSL package or port:
 
 [source,shell]
 ....
 # pkg install openssl
 ....
 
 From the directory where [.filename]#ca.crt# is stored (in this example, [.filename]#/usr/local/etc/openldap#), run:
 
 [source,shell]
 ....
 # c_rehash .
 ....
 
 Both the CA and the server certificate are now correctly recognized in their respective roles.
 To verify this, run this command from the [.filename]#server.crt# directory:
 
 [source,shell]
 ....
 # openssl verify -verbose -CApath . server.crt
 ....
 
 If [.filename]#slapd# was running, restart it.
 As stated in [.filename]#/usr/local/etc/rc.d/slapd#, to properly run [.filename]#slapd# at boot the following lines must be added to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 slapd_enable="YES"
 slapd_flags='-h "ldapi://%2fvar%2frun%2fopenldap%2fldapi/
 ldap://0.0.0.0/"'
 slapd_sockets="/var/run/openldap/ldapi"
 slapd_cn_config="YES"
 ....
 
 [.filename]#slapd# does not provide debugging at boot.
 Check [.filename]#/var/log/debug.log#, [.filename]#dmesg -a# and [.filename]#/var/log/messages# for this purpose.
 
 The following example adds the group `team` and the user `john` to the `domain.example` LDAP database, which is still empty.
 First, create the file [.filename]#domain.ldif#:
 
 [source,shell]
 ....
 # cat domain.ldif
 dn: dc=domain,dc=example
 objectClass: dcObject
 objectClass: organization
 o: domain.example
 dc: domain
 
 dn: ou=groups,dc=domain,dc=example
 objectClass: top
 objectClass: organizationalunit
 ou: groups
 
 dn: ou=users,dc=domain,dc=example
 objectClass: top
 objectClass: organizationalunit
 ou: users
 
 dn: cn=team,ou=groups,dc=domain,dc=example
 objectClass: top
 objectClass: posixGroup
 cn: team
 gidNumber: 10001
 
 dn: uid=john,ou=users,dc=domain,dc=example
 objectClass: top
 objectClass: account
 objectClass: posixAccount
 objectClass: shadowAccount
 cn: John McUser
 uid: john
 uidNumber: 10001
 gidNumber: 10001
 homeDirectory: /home/john/
 loginShell: /usr/bin/bash
 userPassword: secret
 ....
 
 See the OpenLDAP documentation for more details.
 Use [.filename]#slappasswd# to replace the plain text password `secret` with a hash in `userPassword`.
 The path specified as `loginShell` must exist in all the systems where `john` is allowed to login.
 Finally, use the `mdb` administrator to modify the database:
 
 [source,shell]
 ....
 # ldapadd -W -D "cn=mdbadmin,dc=domain,dc=example" -f domain.ldif
 ....
 
 Modifications to the _global configuration_ section can only be performed by the global super-user.
 For example, assume that the option `olcTLSCipherSuite: HIGH:MEDIUM:SSLv3` was initially specified and must now be deleted.
 First, create a file that contains the following:
 
 [source,shell]
 ....
 # cat global_mod
 dn: cn=config
 changetype: modify
 delete: olcTLSCipherSuite
 ....
 
 Then, apply the modifications:
 
 [source,shell]
 ....
 # ldapmodify -f global_mod -x -D "cn=config" -W
 ....
 
 When asked, provide the password chosen in the _configuration backend_ section.
 The username is not required: here, `cn=config` represents the DN of the database section to be modified.
 Alternatively, use `ldapmodify` to delete a single line of the database, `ldapdelete` to delete a whole entry.
 
 If something goes wrong, or if the global super-user cannot access the configuration backend, it is possible to delete and re-write the whole configuration:
 
 [source,shell]
 ....
 # rm -rf /usr/local/etc/openldap/slapd.d/
 ....
 
 [.filename]#slapd.ldif# can then be edited and imported again.
 Please, follow this procedure only when no other solution is available.
 
 This is the configuration of the server only.
 The same machine can also host an LDAP client, with its own separate configuration.
 
 [[network-dhcp]]
 == Dynamic Host Configuration Protocol (DHCP)
 
 The Dynamic Host Configuration Protocol (DHCP) allows a system to connect to a network in order to be assigned the necessary addressing information for communication on that network.
 FreeBSD includes the OpenBSD version of `dhclient` which is used by the client to obtain the addressing information.
 FreeBSD does not install a DHCP server, but several servers are available in the FreeBSD Ports Collection.
 The DHCP protocol is fully described in http://www.freesoft.org/CIE/RFC/2131/[RFC 2131].
 Informational resources are also available at http://www.isc.org/downloads/dhcp/[isc.org/downloads/dhcp/].
 
 This section describes how to use the built-in DHCP client.
 It then describes how to install and configure a DHCP server.
 
 [NOTE]
 ====
 In FreeBSD, the man:bpf[4] device is needed by both the DHCP server and DHCP client.
 This device is included in the [.filename]#GENERIC# kernel that is installed with FreeBSD.
 Users who prefer to create a custom kernel need to keep this device if DHCP is used.
 
 It should be noted that [.filename]#bpf# also allows privileged users to run network packet sniffers on that system.
 ====
 
 
 === Configuring a DHCP Client
 
 DHCP client support is included in the FreeBSD installer, making it easy to configure a newly installed system to automatically receive its networking addressing information from an existing DHCP server.
 Refer to crossref:bsdinstall[bsdinstall-post,"Accounts, Time Zone, Services and Hardening"] for examples of network configuration.
 
 When `dhclient` is executed on the client machine, it begins broadcasting requests for configuration information.
 By default, these requests use UDP port 68.
 The server replies on UDP port 67, giving the client an IP address and other relevant network information such as a subnet mask, default gateway, and DNS server addresses.
 This information is in the form of a DHCP "lease" and is valid for a configurable time.
 This allows stale IP addresses for clients no longer connected to the network to automatically be reused.
 DHCP clients can obtain a great deal of information from the server.
 An exhaustive list may be found in man:dhcp-options[5].
 
 By default, when a FreeBSD system boots, its DHCP client runs in the background, or _asynchronously_.
 Other startup scripts continue to run while the DHCP process completes, which speeds up system startup.
 
 Background DHCP works well when the DHCP server responds quickly to the client's requests.
 However, DHCP may take a long time to complete on some systems.
 If network services attempt to run before DHCP has assigned the network addressing information, they will fail.
 Using DHCP in _synchronous_ mode prevents this problem as it pauses startup until the DHCP configuration has completed.
 
 This line in [.filename]#/etc/rc.conf# is used to configure background or asynchronous mode:
 
 [.programlisting]
 ....
 ifconfig_fxp0="DHCP"
 ....
 
 This line may already exist if the system was configured to use DHCP during installation.
 Replace the _fxp0_ shown in these examples with the name of the interface to be dynamically configured, as described in crossref:config[config-network-setup,“Setting Up Network Interface Cards”].
 
 To instead configure the system to use synchronous mode, and to pause during startup while DHCP completes, use "`SYNCDHCP`":
 
 [.programlisting]
 ....
 ifconfig_fxp0="SYNCDHCP"
 ....
 
 Additional client options are available.
 Search for `dhclient` in man:rc.conf[5] for details.
 
 The DHCP client uses the following files:
 
 * [.filename]#/etc/dhclient.conf#
-+ 
++
 The configuration file used by `dhclient`.
 Typically, this file contains only comments as the defaults are suitable for most clients.
 This configuration file is described in man:dhclient.conf[5].
 * [.filename]#/sbin/dhclient#
-+ 
++
 More information about the command itself can be found in man:dhclient[8].
 * [.filename]#/sbin/dhclient-script#
-+ 
++
 The FreeBSD-specific DHCP client configuration script.
 It is described in man:dhclient-script[8], but should not need any user modification to function properly.
 * [.filename]#/var/db/dhclient.leases.interface#
-+ 
++
 The DHCP client keeps a database of valid leases in this file, which is written as a log and is described in man:dhclient.leases[5].
 
 
 [[network-dhcp-server]]
 === Installing and Configuring a DHCP Server
 
 This section demonstrates how to configure a FreeBSD system to act as a DHCP server using the Internet Systems Consortium (ISC) implementation of the DHCP server.
 This implementation and its documentation can be installed using the package:net/isc-dhcp43-server[] package or port.
 
 The installation of package:net/isc-dhcp43-server[] installs a sample configuration file.
 Copy [.filename]#/usr/local/etc/dhcpd.conf.example# to [.filename]#/usr/local/etc/dhcpd.conf# and make any edits to this new file.
 
 The configuration file is comprised of declarations for subnets and hosts which define the information that is provided to DHCP clients.
 For example, these lines configure the following:
 
 [.programlisting]
 ....
 option domain-name "example.org";<.>
 option domain-name-servers ns1.example.org;<.>
 option subnet-mask 255.255.255.0;<.>
 
 default-lease-time 600;<.>
 max-lease-time 72400;<.>
 ddns-update-style none;<.>
 
 subnet 10.254.239.0 netmask 255.255.255.224 {
   range 10.254.239.10 10.254.239.20;<.>
   option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;<.>
 }
 
 host fantasia {
   hardware ethernet 08:00:07:26:c0:a5;<.>
   fixed-address fantasia.fugue.com;<.>
 }
 ....
 
 <.> This option specifies the default search domain that will be provided to clients. Refer to man:resolv.conf[5] for more information.
 <.> This option specifies a comma separated list of DNS servers that the client should use. They can be listed by their Fully Qualified Domain Names (FQDN), as seen in the example, or by their IP addresses.
 <.> The subnet mask that will be provided to clients.
 <.> The default lease expiry time in seconds. A client can be configured to override this value.
 <.> The maximum allowed length of time, in seconds, for a lease. Should a client request a longer lease, a lease will still be issued, but it will only be valid for `max-lease-time`.
 <.> The default of `none` disables dynamic DNS updates. Changing this to `interim` configures the DHCP server to update a DNS server whenever it hands out a lease so that the DNS server knows which IP addresses are associated with which computers in the network. Do not change the default setting unless the DNS server has been configured to support dynamic DNS.
 <.> This line creates a pool of available IP addresses which are reserved for allocation to DHCP clients. The range of addresses must be valid for the network or subnet specified in the previous line.
 <.> Declares the default gateway that is valid for the network or subnet specified before the opening `{` bracket.
 <.> Specifies the hardware MAC address of a client so that the DHCP server can recognize the client when it makes a request.
 <.> Specifies that this host should always be given the same IP address. Using the hostname is correct, since the DHCP server will resolve the hostname before returning the lease information.
 
 This configuration file supports many more options.
 Refer to dhcpd.conf(5), installed with the server, for details and examples.
 
 Once the configuration of [.filename]#dhcpd.conf# is complete, enable the DHCP server in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 dhcpd_enable="YES"
 dhcpd_ifaces="dc0"
 ....
 
 Replace the `dc0` with the interface (or interfaces, separated by whitespace) that the DHCP server should listen on for DHCP client requests.
 
 Start the server by issuing the following command:
 
 [source,shell]
 ....
 # service isc-dhcpd start
 ....
 
 Any future changes to the configuration of the server will require the dhcpd service to be stopped and then started using man:service[8].
 
 The DHCP server uses the following files.
 Note that the manual pages are installed with the server software.
 
 * [.filename]#/usr/local/sbin/dhcpd#
-+ 
++
 More information about the dhcpd server can be found in dhcpd(8).
 * [.filename]#/usr/local/etc/dhcpd.conf#
-+ 
++
 The server configuration file needs to contain all the information that should be provided to clients, along with information regarding the operation of the server.
 This configuration file is described in dhcpd.conf(5).
 * [.filename]#/var/db/dhcpd.leases#
-+ 
++
 The DHCP server keeps a database of leases it has issued in this file, which is written as a log.
 Refer to dhcpd.leases(5), which gives a slightly longer description.
 * [.filename]#/usr/local/sbin/dhcrelay#
-+ 
++
 This daemon is used in advanced environments where one DHCP server forwards a request from a client to another DHCP server on a separate network.
 If this functionality is required, install the package:net/isc-dhcp43-relay[] package or port.
 The installation includes dhcrelay(8) which provides more detail.
 
 
 [[network-dns]]
 == Domain Name System (DNS)
 
 Domain Name System (DNS) is the protocol through which domain names are mapped to IP addresses, and vice versa.
 DNS is coordinated across the Internet through a somewhat complex system of authoritative root, Top Level Domain (TLD), and other smaller-scale name servers, which host and cache individual domain information.
 It is not necessary to run a name server to perform DNS lookups on a system.
 
 The following table describes some of the terms associated with DNS:
 
 .DNS Terminology
 [cols="1,1", frame="none", options="header"]
 |===
 | Term
 | Definition
 
 |Forward DNS
 |Mapping of hostnames to IP addresses.
 
 |Origin
 |Refers to the domain covered in a particular zone file.
 
 |Resolver
 |A system process through which a machine queries a name server for zone information.
 
 |Reverse DNS
 |Mapping of IP addresses to hostnames.
 
 |Root zone
 |The beginning of the Internet zone hierarchy. All zones fall under the root zone, similar to how all files in a file system fall under the root directory.
 
 |Zone
 |An individual domain, subdomain, or portion of the DNS administered by the same authority.
 |===
 
 Examples of zones:
 
 * `.` is how the root zone is usually referred to in documentation.
 * `org.` is a Top Level Domain (TLD) under the root zone.
 * `example.org.` is a zone under the `org.`TLD.
 * `1.168.192.in-addr.arpa` is a zone referencing all IP addresses which fall under the `192.168.1.*`IP address space.
 
 As one can see, the more specific part of a hostname appears to its left.
 For example, `example.org.` is more specific than `org.`, as `org.` is more specific than the root zone.
 The layout of each part of a hostname is much like a file system: the [.filename]#/dev# directory falls within the root, and so on.
 
 === Reasons to Run a Name Server
 
 Name servers generally come in two forms: authoritative name servers, and caching (also known as resolving) name servers.
 
 An authoritative name server is needed when:
 
 * One wants to serve DNS information to the world, replying authoritatively to queries.
 * A domain, such as `example.org`, is registered and IP addresses need to be assigned to hostnames under it.
 * An IP address block requires reverse DNS entries (IP to hostname).
 * A backup or second name server, called a slave, will reply to queries.
 
 A caching name server is needed when:
 
 * A local DNS server may cache and respond more quickly than querying an outside name server.
 
 When one queries for `www.FreeBSD.org`, the resolver usually queries the uplink ISP's name server, and retrieves the reply.
 With a local, caching DNS server, the query only has to be made once to the outside world by the caching DNS server.
 Additional queries will not have to go outside the local network, since the information is cached locally.
 
 === DNS Server Configuration
 
 Unbound is provided in the FreeBSD base system.
 By default, it will provide DNS resolution to the local machine only.
 While the base system package can be configured to provide resolution services beyond the local machine, it is recommended that such requirements be addressed by installing Unbound from the FreeBSD Ports Collection.
 
 To enable Unbound, add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 local_unbound_enable="YES"
 ....
 
 Any existing nameservers in [.filename]#/etc/resolv.conf# will be configured as forwarders in the new Unbound configuration.
 
 [NOTE]
 ====
 If any of the listed nameservers do not support DNSSEC, local DNS resolution will fail.
 Be sure to test each nameserver and remove any that fail the test.
 The following command will show the trust tree or a failure for a nameserver running on `192.168.1.1`:
 ====
 
 
 [source,shell]
 ....
 % drill -S FreeBSD.org @192.168.1.1
 ....
 
 Once each nameserver is confirmed to support DNSSEC, start Unbound:
 
 [source,shell]
 ....
 # service local_unbound onestart
 ....
 
 This will take care of updating [.filename]#/etc/resolv.conf# so that queries for DNSSEC secured domains will now work.
 For example, run the following to validate the FreeBSD.org DNSSEC trust tree:
 
 [source,shell]
 ....
 % drill -S FreeBSD.org
 ;; Number of trusted keys: 1
 ;; Chasing: freebsd.org. A
 
 DNSSEC Trust tree:
 freebsd.org. (A)
 |---freebsd.org. (DNSKEY keytag: 36786 alg: 8 flags: 256)
     |---freebsd.org. (DNSKEY keytag: 32659 alg: 8 flags: 257)
     |---freebsd.org. (DS keytag: 32659 digest type: 2)
         |---org. (DNSKEY keytag: 49587 alg: 7 flags: 256)
             |---org. (DNSKEY keytag: 9795 alg: 7 flags: 257)
             |---org. (DNSKEY keytag: 21366 alg: 7 flags: 257)
             |---org. (DS keytag: 21366 digest type: 1)
             |   |---. (DNSKEY keytag: 40926 alg: 8 flags: 256)
             |       |---. (DNSKEY keytag: 19036 alg: 8 flags: 257)
             |---org. (DS keytag: 21366 digest type: 2)
                 |---. (DNSKEY keytag: 40926 alg: 8 flags: 256)
                     |---. (DNSKEY keytag: 19036 alg: 8 flags: 257)
 ;; Chase successful
 ....
 
 
 [[network-apache]]
 == Apache HTTP Server
 
 The open source Apache HTTP Server is the most widely used web server.
 FreeBSD does not install this web server by default, but it can be installed from the package:www/apache24[] package or port.
 
 This section summarizes how to configure and start version 2._x_ of the Apache HTTP Server on FreeBSD.
 For more detailed information about Apache 2.X and its configuration directives, refer to http://httpd.apache.org/[httpd.apache.org].
 
 === Configuring and Starting Apache
 
 In FreeBSD, the main Apache HTTP Server configuration file is installed as [.filename]#/usr/local/etc/apache2x/httpd.conf#, where _x_ represents the version number.
 This ASCII text file begins comment lines with a `#`.
 The most frequently modified directives are:
 
 `ServerRoot "/usr/local"`::
 Specifies the default directory hierarchy for the Apache installation.
 Binaries are stored in the [.filename]#bin# and [.filename]#sbin# subdirectories of the server root and configuration files are stored in the [.filename]#etc/apache2x# subdirectory.
 
 `ServerAdmin you@example.com`::
 Change this to the email address to receive problems with the server.
 This address also appears on some server-generated pages, such as error documents.
 
 `ServerName www.example.com:80`::
 Allows an administrator to set a hostname which is sent back to clients for the server.
 For example, `www` can be used instead of the actual hostname.
 If the system does not have a registered DNS name, enter its IP address instead.
 If the server will listen on an alternate report, change `80` to the alternate port number.
 
 `DocumentRoot "/usr/local/www/apache2_x_/data"`::
 The directory where documents will be served from.
 By default, all requests are taken from this directory, but symbolic links and aliases may be used to point to other locations.
 
 It is always a good idea to make a backup copy of the default Apache configuration file before making changes.
 When the configuration of Apache is complete, save the file and verify the configuration using `apachectl`.
 Running `apachectl configtest` should return `Syntax OK`.
 
 To launch Apache at system startup, add the following line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 apache24_enable="YES"
 ....
 
 If Apache should be started with non-default options, the following line may be added to [.filename]#/etc/rc.conf# to specify the needed flags:
 
 [.programlisting]
 ....
 apache24_flags=""
 ....
 
 If apachectl does not report configuration errors, start `httpd` now:
 
 [source,shell]
 ....
 # service apache24 start
 ....
 
 The `httpd` service can be tested by entering `http://_localhost_` in a web browser, replacing _localhost_ with the fully-qualified domain name of the machine running `httpd`.
 The default web page that is displayed is [.filename]#/usr/local/www/apache24/data/index.html#.
 
 The Apache configuration can be tested for errors after making subsequent configuration changes while `httpd` is running using the following command:
 
 [source,shell]
 ....
 # service apache24 configtest
 ....
 
 [NOTE]
 ====
 It is important to note that `configtest` is not an man:rc[8] standard, and should not be expected to work for all startup scripts.
 ====
 
 === Virtual Hosting
 
 Virtual hosting allows multiple websites to run on one Apache server.
 The virtual hosts can be _IP-based_ or _name-based_.
 IP-based virtual hosting uses a different IP address for each website.
 Name-based virtual hosting uses the clients HTTP/1.1 headers to figure out the hostname, which allows the websites to share the same IP address.
 
 To setup Apache to use name-based virtual hosting, add a `VirtualHost` block for each website.
 For example, for the webserver named `www.domain.tld` with a virtual domain of `www.someotherdomain.tld`, add the following entries to [.filename]#httpd.conf#:
 
 [.programlisting]
 ....
 <VirtualHost *>
     ServerName www.domain.tld
     DocumentRoot /www/domain.tld
 </VirtualHost>
 
 <VirtualHost *>
     ServerName www.someotherdomain.tld
     DocumentRoot /www/someotherdomain.tld
 </VirtualHost>
 ....
 
 For each virtual host, replace the values for `ServerName` and `DocumentRoot` with the values to be used.
 
 For more information about setting up virtual hosts, consult the official Apache documentation at: http://httpd.apache.org/docs/vhosts/[http://httpd.apache.org/docs/vhosts/].
 
 === Apache Modules
 
 Apache uses modules to augment the functionality provided by the basic server.
 Refer to http://httpd.apache.org/docs/current/mod/[http://httpd.apache.org/docs/current/mod/] for a complete listing of and the configuration details for the available modules.
 
 In FreeBSD, some modules can be compiled with the package:www/apache24[] port.
 Type `make config` within [.filename]#/usr/ports/www/apache24# to see which modules are available and which are enabled by default.
 If the module is not compiled with the port, the FreeBSD Ports Collection provides an easy way to install many modules.
 This section describes three of the most commonly used modules.
 
 ==== SSL support
 
 At one in point in time, support for SSL inside of Apache required a secondary module called [.filename]#mod_ssl#.
 This is no longer the case and the default install of Apache comes with SSL built into the web server.
 An example of how to enable support for SSL websites is available in the installed file, [.filename]#httpd-ssl.conf# inside of the [.filename]#/usr/local/etc/apache24/extra# directory
 Inside this directory is also a sample file called named [.filename]#ssl.conf-sample#.
 It is recommended that both files be evaluated to properly set up secure websites in the Apache web server.
 
 After the configuration of SSL is complete, the following line must be uncommented in the main [.filename]#http.conf# to activate the changes on the next restart or reload of Apache:
 
 [.programlisting]
 ....
 #Include etc/apache24/extra/httpd-ssl.conf
 ....
 
 [WARNING]
 ====
 SSL version two and version three have known vulnerability issues.
 It is highly recommended TLS version 1.2 and 1.3 be enabled in place of the older SSL options.
 This can be accomplished by setting the following options in the [.filename]#ssl.conf#:
 ====
 
 
 [.programlisting]
 ....
 SSLProtocol all -SSLv3 -SSLv2 +TLSv1.2 +TLSv1.3
 SSLProxyProtocol all -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
 ....
 
 To complete the configuration of SSL in the web server, uncomment the following line to ensure that the configuration will be pulled into Apache during restart or reload:
 
 [.programlisting]
 ....
 # Secure (SSL/TLS) connections
 Include etc/apache24/extra/httpd-ssl.conf
 ....
 
 The following lines must also be uncommented in the [.filename]#httpd.conf# to fully support SSL in Apache:
 
 [.programlisting]
 ....
 LoadModule authn_socache_module libexec/apache24/mod_authn_socache.so
 LoadModule socache_shmcb_module libexec/apache24/mod_socache_shmcb.so
 LoadModule ssl_module libexec/apache24/mod_ssl.so
 ....
 
 The next step is to work with a certificate authority to have the appropriate certificates installed on the system.
 This will set up a chain of trust for the site and prevent any warnings of self-signed certificates.
 
 ==== [.filename]#mod_perl#
 
 The [.filename]#mod_perl# module makes it possible to write Apache modules in Perl.
 In addition, the persistent interpreter embedded in the server avoids the overhead of starting an external interpreter and the penalty of Perl start-up time.
 
 The [.filename]#mod_perl# can be installed using the package:www/mod_perl2[] package or port.
 Documentation for using this module can be found at http://perl.apache.org/docs/2.0/index.html[http://perl.apache.org/docs/2.0/index.html].
 
 ==== [.filename]#mod_php#
 
 _PHP: Hypertext Preprocessor_ (PHP) is a general-purpose scripting language that is especially suited for web development.
 Capable of being embedded into HTML, its syntax draws upon C, Java(TM), and Perl with the intention of allowing web developers to write dynamically generated webpages quickly.
 
 Support for PHP for Apache and any other feature written in the language, can be added by installing the appropriate port.
 
 For all supported versions, search the package database using `pkg`:
 
 [source,shell]
 ....
 # pkg search php
 ....
 
 A list will be displayed including the versions and additional features they provide.
 The components are completely modular, meaning features are enabled by installing the appropriate port.
 To install PHP version 7.4 for Apache, issue the following command:
 
 [source,shell]
 ....
 # pkg install mod_php74
 ....
 
 If any dependency packages need to be installed, they will be installed as well.
 
 By default, PHP will not be enabled.
 The following lines will need to be added to the Apache configuration file located in [.filename]#/usr/local/etc/apache24# to make it active:
 
 [.programlisting]
 ....
 <FilesMatch "\.php$">
     SetHandler application/x-httpd-php
 </FilesMatch>
 <FilesMatch "\.phps$">
     SetHandler application/x-httpd-php-source
 </FilesMatch>
 ....
 
 In addition, the `DirectoryIndex` in the configuration file will also need to be updated and Apache will either need to be restarted or reloaded for the changes to take effect.
 
 Support for many of the PHP features may also be installed by using `pkg`.
 For example, to install support for XML or SSL, install their respective ports:
 
 [source,shell]
 ....
 # pkg install php74-xml php74-openssl
 ....
 
 As before, the Apache configuration will need to be reloaded for the changes to take effect, even in cases where it was just a module install.
 
 To perform a graceful restart to reload the configuration, issue the following command:
 
 [source,shell]
 ....
 # apachectl graceful
 ....
 
 Once the install is complete, there are two methods of obtaining the installed PHP support modules and the environmental information of the build.
 The first is to install the full PHP binary and running the command to gain the information:
 
 [source,shell]
 ....
 # pkg install php74
 ....
 
 
 [source,shell]
 ....
 # php -i |less
 ....
 
 It is necessary to pass the output to a pager, such as the `more` or `less` to easier digest the amount of output.
 
 Finally, to make any changes to the global configuration of PHP there is a well documented file installed into [.filename]#/usr/local/etc/php.ini#.
 At the time of install, this file will not exist because there are two versions to choose from, one is [.filename]#php.ini-development# and the other is [.filename]#php.ini-production#.
 These are starting points to assist administrators in their deployment.
 
 ==== HTTP2 Support
 
 Apache support for the HTTP2 protocol is included by default when installing the port with `pkg`.
 The new version of HTTP includes many improvements over the previous version, including utilizing a single connection to a website, reducing overall roundtrips of TCP connections.
 Also, packet header data is compressed and HTTP2 requires encryption by default.
 
 When Apache is configured to only use HTTP2, web browsers will require secure, encrypted HTTPS connections.
 When Apache is configured to use both versions, HTTP1.1 will be considered a fall back option if any issues arise during the connection.
 
 While this change does require administrators to make changes, they are positive and equate to a more secure Internet for everyone.
 The changes are only required for sites not currently implementing SSL and TLS.
 
 [NOTE]
 ====
 This configuration depends on the previous sections, including TLS support.
 It is recommended those instructions be followed before continuing with this configuration.
 ====
 
 Start the process by enabling the http2 module by uncommenting the line in [.filename]#/usr/local/etc/apache24/httpd.conf# and replace the mpm_prefork module with mpm_event as the former does not support HTTP2.
 
 [.programlisting]
 ....
 LoadModule http2_module libexec/apache24/mod_http2.so
 LoadModule mpm_event_module libexec/apache24/mod_mpm_event.so
 ....
 
 [NOTE]
 ====
 There is a separate [.filename]#mod_http2# port that is available.
 It exists to deliver security and bug fixes quicker than the module installed with the bundled [.filename]#apache24# port.
 It is not required for HTTP2 support but is available.
 When installed, the [.filename]#mod_h2.so# should be used in place of [.filename]#mod_http2.so# in the Apache configuration.
 ====
 
 There are two methods to implement HTTP2 in Apache; one way is globally for all sites and each VirtualHost running on the system.
 To enable HTTP2 globally, add the following line under the ServerName directive:
 
 [.programlisting]
 ....
 Protocols h2 http/1.1
 ....
 
 [NOTE]
 ====
 To enable HTTP2 over plaintext, use h2h2chttp/1.1 in the [.filename]#httpd.conf#.
 ====
 
 Having the h2c here will allow plaintext HTTP2 data to pass on the system but is not recommended.
 In addition, using the http/1.1 here will allow fallback to the HTTP1.1 version of the protocol should it be needed by the system.
 
 To enable HTTP2 for individual VirtualHosts, add the same line within the VirtualHost directive in either [.filename]#httpd.conf# or [.filename]#httpd-ssl.conf#.
 
 Reload the configuration using the `apachectl`[parameter]#reload# command and test the configuration either by using either of the following methods after visiting one of the hosted pages:
 
 [source,shell]
 ....
 # grep "HTTP/2.0" /var/log/httpd-access.log
 ....
 
 This should return something similar to the following:
 
 [.programlisting]
 ....
 192.168.1.205 - - [18/Oct/2020:18:34:36 -0400] "GET / HTTP/2.0" 304 -
 192.0.2.205 - - [18/Oct/2020:19:19:57 -0400] "GET / HTTP/2.0" 304 -
 192.0.0.205 - - [18/Oct/2020:19:20:52 -0400] "GET / HTTP/2.0" 304 -
 192.0.2.205 - - [18/Oct/2020:19:23:10 -0400] "GET / HTTP/2.0" 304 -
 ....
 
 The other method is using the web browser's built in site debugger or `tcpdump`; however, using either method is beyond the scope of this document.
 
 Support for HTTP2 reverse proxy connections by using the [.filename]#mod_proxy_http2.so# module.
 When configuring the ProxyPass or RewriteRules [P] statements, they should use h2:// for the connection.
 
 === Dynamic Websites
 
 In addition to mod_perl and mod_php, other languages are available for creating dynamic web content.
 These include Django and Ruby on Rails.
 
 ==== Django
 
 Django is a BSD-licensed framework designed to allow developers to write high performance, elegant web applications quickly.
 It provides an object-relational mapper so that data types are developed as Python objects.
 A rich dynamic database-access API is provided for those objects without the developer ever having to write SQL.
 It also provides an extensible template system so that the logic of the application is separated from the HTML presentation.
 
 Django depends on [.filename]#mod_python#, and an SQL database engine.
 In FreeBSD, the package:www/py-django[] port automatically installs [.filename]#mod_python# and supports the PostgreSQL, MySQL, or SQLite databases, with the default being SQLite.
 To change the database engine, type `make config` within [.filename]#/usr/ports/www/py-django#, then install the port.
 
 Once Django is installed, the application will need a project directory along with the Apache configuration in order to use the embedded Python interpreter.
 This interpreter is used to call the application for specific URLs on the site.
 
 To configure Apache to pass requests for certain URLs to the web application, add the following to [.filename]#httpd.conf#, specifying the full path to the project directory:
 
 [.programlisting]
 ....
 <Location "/">
     SetHandler python-program
     PythonPath "['/dir/to/the/django/packages/'] + sys.path"
     PythonHandler django.core.handlers.modpython
     SetEnv DJANGO_SETTINGS_MODULE mysite.settings
     PythonAutoReload On
     PythonDebug On
 </Location>
 ....
 
 Refer to https://docs.djangoproject.com[https://docs.djangoproject.com] for more information on how to use Django.
 
 ==== Ruby on Rails
 
 Ruby on Rails is another open source web framework that provides a full development stack.
 It is optimized to make web developers more productive and capable of writing powerful applications quickly.
 On FreeBSD, it can be installed using the package:www/rubygem-rails[] package or port.
 
 Refer to http://guides.rubyonrails.org[http://guides.rubyonrails.org] for more information on how to use Ruby on Rails.
 
 [[network-ftp]]
 == File Transfer Protocol (FTP)
 
 The File Transfer Protocol (FTP) provides users with a simple way to transfer files to and from an FTP server.
 FreeBSD includes FTP server software, ftpd, in the base system.
 
 FreeBSD provides several configuration files for controlling access to the FTP server.
 This section summarizes these files.
 Refer to man:ftpd[8] for more details about the built-in FTP server.
 
 === Configuration
 
 The most important configuration step is deciding which accounts will be allowed access to the FTP server.
 A FreeBSD system has a number of system accounts which should not be allowed FTP access.
 The list of users disallowed any FTP access can be found in [.filename]#/etc/ftpusers#. By default, it includes system accounts.
 Additional users that should not be allowed access to FTP can be added.
 
 In some cases it may be desirable to restrict the access of some users without preventing them completely from using FTP.
 This can be accomplished be creating [.filename]#/etc/ftpchroot# as described in man:ftpchroot[5].
 This file lists users and groups subject to FTP access restrictions.
 
 To enable anonymous FTP access to the server, create a user named `ftp` on the FreeBSD system.
 Users will then be able to log on to the FTP server with a username of `ftp` or `anonymous`.
 When prompted for the password, any input will be accepted, but by convention, an email address should be used as the password.
 The FTP server will call man:chroot[2] when an anonymous user logs in, to restrict access to only the home directory of the `ftp` user.
 
 There are two text files that can be created to specify welcome messages to be displayed to FTP clients.
 The contents of [.filename]#/etc/ftpwelcome# will be displayed to users before they reach the login prompt.
 After a successful login, the contents of [.filename]#/etc/ftpmotd# will be displayed.
 Note that the path to this file is relative to the login environment, so the contents of [.filename]#~ftp/etc/ftpmotd# would be displayed for anonymous users.
 
 Once the FTP server has been configured, set the appropriate variable in [.filename]#/etc/rc.conf# to start the service during boot:
 
 [.programlisting]
 ....
 ftpd_enable="YES"
 ....
 
 To start the service now:
 
 [source,shell]
 ....
 # service ftpd start
 ....
 
 Test the connection to the FTP server by typing:
 
 [source,shell]
 ....
 % ftp localhost
 ....
 
 The ftpd daemon uses man:syslog[3] to log messages.
 By default, the system log daemon will write messages related to FTP in [.filename]#/var/log/xferlog#.
 The location of the FTP log can be modified by changing the following line in [.filename]#/etc/syslog.conf#:
 
 [.programlisting]
 ....
 ftp.info      /var/log/xferlog
 ....
 
 
 [NOTE]
 ====
 Be aware of the potential problems involved with running an anonymous FTP server.
 In particular, think twice about allowing anonymous users to upload files.
 It may turn out that the FTP site becomes a forum for the trade of unlicensed commercial software or worse.
 If anonymous FTP uploads are required, then verify the permissions so that these files cannot be read by other anonymous users until they have been reviewed by an administrator.
 ====
 
 [[network-samba]]
 == File and Print Services for Microsoft(R) Windows(R) Clients (Samba)
 
 Samba is a popular open source software package that provides file and print services using the SMB/CIFS protocol.
 This protocol is built into Microsoft(R) Windows(R) systems.
 It can be added to non-Microsoft(R) Windows(R) systems by installing the Samba client libraries.
 The protocol allows clients to access shared data and printers.
 These shares can be mapped as a local disk drive and shared printers can be used as if they were local printers.
 
 On FreeBSD, the Samba client libraries can be installed using the package:net/samba413[] port or package.
 The client provides the ability for a FreeBSD system to access SMB/CIFS shares in a Microsoft(R) Windows(R) network.
 
 A FreeBSD system can also be configured to act as a Samba server by installing the same package:net/samba413[] port or package.
 This allows the administrator to create SMB/CIFS shares on the FreeBSD system which can be accessed by clients running Microsoft(R) Windows(R) or the Samba client libraries.
 
 === Server Configuration
 
 Samba is configured in [.filename]#/usr/local/etc/smb4.conf#.
 This file must be created before Samba can be used.
 
 A simple [.filename]#smb4.conf# to share directories and printers with Windows(R) clients in a workgroup is shown here.
 For more complex setups involving LDAP or Active Directory, it is easier to use man:samba-tool[8] to create the initial [.filename]#smb4.conf#.
 
 [.programlisting]
 ....
 [global]
 workgroup = WORKGROUP
 server string = Samba Server Version %v
 netbios name = ExampleMachine
 wins support = Yes
 security = user
 passdb backend = tdbsam
 
 # Example: share /usr/src accessible only to 'developer' user
 [src]
 path = /usr/src
 valid users = developer
 writable  = yes
 browsable = yes
 read only = no
 guest ok = no
 public = no
 create mask = 0666
 directory mask = 0755
 ....
 
 
 ==== Global Settings
 
 Settings that describe the network are added in [.filename]#/usr/local/etc/smb4.conf#:
 
 `workgroup`::
 The name of the workgroup to be served.
 
 `netbios name`::
 The NetBIOS name by which a Samba server is known.
 By default, it is the same as the first component of the host's DNS name.
 
 `server string`::
 The string that will be displayed in the output of `net view` and some other networking tools that seek to display descriptive text about the server.
 
 `wins support`::
 Whether Samba will act as a WINS server.
 Do not enable support for WINS on more than one server on the network.
 
 
 ==== Security Settings
 
 The most important settings in [.filename]#/usr/local/etc/smb4.conf# are the security model and the backend password format.
 These directives control the options:
 
 `security`::
 The most common settings are `security = share` and `security = user`.
 If the clients use usernames that are the same as their usernames on the FreeBSD machine, user level security should be used.
 This is the default security policy and it requires clients to first log on before they can access shared resources.
 +
 In share level security, clients do not need to log onto the server with a valid username and password before attempting to connect to a shared resource. 
 This was the default security model for older versions of Samba.
 
 `passdb backend`::
 Samba has several different backend authentication models.
 Clients may be authenticated with LDAP, NIS+, an SQL database, or a modified password file.
 The recommended authentication method, `tdbsam`, is ideal for simple networks and is covered here.
 For larger or more complex networks, `ldapsam` is recommended.
 `smbpasswd` was the former default and is now obsolete.
 
 ==== Samba Users
 
 FreeBSD user accounts must be mapped to the `SambaSAMAccount` database for Windows(R) clients to access the share.
 Map existing FreeBSD user accounts using man:pdbedit[8]:
 
 [source,shell]
 ....
 # pdbedit -a username
 ....
 
 This section has only mentioned the most commonly used settings.
 Refer to the https://wiki.samba.org[Official Samba Wiki] for additional information about the available configuration options.
 
 === Starting Samba
 
 To enable Samba at boot time, add the following line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 samba_server_enable="YES"
 ....
 
 To start Samba now:
 
 [source,shell]
 ....
 # service samba_server start
 Performing sanity check on Samba configuration: OK
 Starting nmbd.
 Starting smbd.
 ....
 
 Samba consists of three separate daemons.
 Both the nmbd and smbd daemons are started by `samba_enable`.
 If winbind name resolution is also required, set:
 
 [.programlisting]
 ....
 winbindd_enable="YES"
 ....
 
 Samba can be stopped at any time by typing:
 
 [source,shell]
 ....
 # service samba_server stop
 ....
 
 Samba is a complex software suite with functionality that allows broad integration with Microsoft(R) Windows(R) networks.
 For more information about functionality beyond the basic configuration described here, refer to https://www.samba.org[https://www.samba.org].
 
 [[network-ntp]]
 == Clock Synchronization with NTP
 
 Over time, a computer's clock is prone to drift.
 This is problematic as many network services require the computers on a network to share the same accurate time.
 Accurate time is also needed to ensure that file timestamps stay consistent.
 The Network Time Protocol (NTP) is one way to provide clock accuracy in a network.
 
 FreeBSD includes man:ntpd[8] which can be configured to query other NTP servers to synchronize the clock on that machine or to provide time services to other computers in the network.
 
 This section describes how to configure ntpd on FreeBSD.
 Further documentation can be found in [.filename]#/usr/share/doc/ntp/# in HTML format.
 
 === NTP Configuration
 
 On FreeBSD, the built-in ntpd can be used to synchronize a system's clock.
 Ntpd is configured using man:rc.conf[5] variables and [.filename]#/etc/ntp.conf#, as detailed in the following sections.
 
 Ntpd communicates with its network peers using UDP packets.
 Any firewalls between your machine and its NTP peers must be configured to allow UDP packets in and out on port 123.
 
 ==== The [.filename]#/etc/ntp.conf# file
 
 Ntpd reads [.filename]#/etc/ntp.conf# to determine which NTP servers to query.
 Choosing several NTP servers is recommended in case one of the servers becomes unreachable or its clock proves unreliable.
 As ntpd receives responses, it favors reliable servers over the less reliable ones.
 The servers which are queried can be local to the network, provided by an ISP, or selected from an http://support.ntp.org/bin/view/Servers/WebHome[ online list of publicly accessible NTP servers].
 When choosing a public NTP server, select one that is geographically close and review its usage policy.
 The `pool` configuration keyword selects one or more servers from a pool of servers.
 An http://support.ntp.org/bin/view/Servers/NTPPoolServers[ online list of publicly accessible NTP pools] is available, organized by geographic area.
 In addition, FreeBSD provides a project-sponsored pool, `0.freebsd.pool.ntp.org`.
 
 .Sample [.filename]#/etc/ntp.conf#
 [example]
 ====
 This is a simple example of an [.filename]#ntp.conf# file.
 It can safely be used as-is; it contains the recommended `restrict` options for operation on a publicly-accessible network connection.
 
 [.programlisting]
 ....
 
 # Disallow ntpq control/query access.  Allow peers to be added only
 # based on pool and server statements in this file.
 restrict default limited kod nomodify notrap noquery nopeer
 restrict source  limited kod nomodify notrap noquery
 
 # Allow unrestricted access from localhost for queries and control.
 restrict 127.0.0.1
 restrict ::1
 
 # Add a specific server.
 server ntplocal.example.com iburst
 
 # Add FreeBSD pool servers until 3-6 good servers are available.
 tos minclock 3 maxclock 6
 pool 0.freebsd.pool.ntp.org iburst
 
 # Use a local leap-seconds file.
 leapfile "/var/db/ntpd.leap-seconds.list"
 ....
 
 ====
 
 The format of this file is described in man:ntp.conf[5].
 The descriptions below provide a quick overview of just the keywords used in the sample file above.
 
 By default, an NTP server is accessible to any network host.
 The `restrict` keyword controls which systems can access the server.
 Multiple `restrict` entries are supported, each one refining the restrictions given in previous statements.
 The values shown in the example grant the local system full query and control access, while allowing remote systems only the ability to query the time. 
 For more details, refer to the `Access Control Support` subsection of man:ntp.conf[5].
 
 The `server` keyword specifies a single server to query.
 The file can contain multiple server keywords, with one server listed on each line.
 The `pool` keyword specifies a pool of servers.
 Ntpd will add one or more servers from this pool as needed to reach the number of peers specified using the `tos minclock` value.
 The `iburst` keyword directs ntpd to perform a burst of eight quick packet exchanges with a server when contact is first established, to help quickly synchronize system time.
 
 The `leapfile` keyword specifies the location of a file containing information about leap seconds.
 The file is updated automatically by man:periodic[8].
 The file location specified by this keyword must match the location set in the `ntp_db_leapfile` variable in [.filename]#/etc/rc.conf#.
 
 ==== NTP entries in [.filename]#/etc/rc.conf#
 
 Set `ntpd_enable=YES` to start ntpd at boot time.
 Once `ntpd_enable=YES` has been added to [.filename]#/etc/rc.conf#, ntpd can be started immediately without rebooting the system by typing:
 
 [source,shell]
 ....
 # service ntpd start
 ....
 
 Only `ntpd_enable` must be set to use ntpd.
 The [.filename]#rc.conf# variables listed below may also be set as needed.
 
 Set `ntpd_sync_on_start=YES` to allow ntpd to step the clock any amount, one time at startup.
 Normally ntpd will log an error message and exit if the clock is off by more than 1000 seconds.
 This option is especially useful on systems without a battery-backed realtime clock.
 
 Set `ntpd_oomprotect=YES` to protect the ntpd daemon from being killed by the system attempting to recover from an Out Of Memory (OOM) condition.
 
 Set `ntpd_config=` to the location of an alternate [.filename]#ntp.conf# file.
 
 Set `ntpd_flags=` to contain any other ntpd flags as needed, but avoid using these flags which are managed internally by [.filename]#/etc/rc.d/ntpd#: 
 
 * `-p` (pid file location)
 * `-c` (set `ntpd_config=` instead)
 
 
 ==== Ntpd and the unpriveleged `ntpd` user
 
 Ntpd on FreeBSD can start and run as an unpriveleged user.
 Doing so requires the man:mac_ntpd[4] policy module.
 The [.filename]#/etc/rc.d/ntpd# startup script first examines the NTP configuration.
 If possible, it loads the `mac_ntpd` module, then starts ntpd as unpriveleged user `ntpd` (user id 123).
 To avoid problems with file and directory access, the startup script will not automatically start ntpd as `ntpd` when the configuration contains any file-related options.
 
 The presence of any of the following in `ntpd_flags` requires manual configuration as described below to run as the `ntpd` user: 
 
 * -f or --driftfile
 * -i or --jaildir
 * -k or --keyfile
 * -l or --logfile
 * -s or --statsdir
 
 The presence of any of the following keywords in [.filename]#ntp.conf# requires manual configuration as described below to run as the `ntpd` user: 
 
 * crypto
 * driftfile
 * key
 * logdir
 * statsdir
 
 To manually configure ntpd to run as user `ntpd` you must: 
 
 * Ensure that the `ntpd` user has access to all the files and directories specified in the configuration.
 * Arrange for the `mac_ntpd` module to be loaded or compiled into the kernel. See man:mac_ntpd[4] for details.
 * Set `ntpd_user="ntpd"` in [.filename]#/etc/rc.conf#
 
 === Using NTP with a PPP Connection
 
 ntpd does not need a permanent connection to the Internet to function properly.
 However, if a PPP connection is configured to dial out on demand, NTP traffic should be prevented from triggering a dial out or keeping the connection alive.
 This can be configured with `filter` directives in [.filename]#/etc/ppp/ppp.conf#. For example:
 
 [.programlisting]
 ....
 set filter dial 0 deny udp src eq 123
 # Prevent NTP traffic from initiating dial out
 set filter dial 1 permit 0 0
 set filter alive 0 deny udp src eq 123
 # Prevent incoming NTP traffic from keeping the connection open
 set filter alive 1 deny udp dst eq 123
 # Prevent outgoing NTP traffic from keeping the connection open
 set filter alive 2 permit 0/0 0/0
 ....
 
 For more details, refer to the `PACKET FILTERING` section in man:ppp[8] and the examples in [.filename]#/usr/share/examples/ppp/#.
 
 [NOTE]
 ====
 Some Internet access providers block low-numbered ports, preventing NTP from functioning since replies never reach the machine.
 ====
 
 [[network-iscsi]]
 == iSCSI Initiator and Target Configuration
 
 iSCSI is a way to share storage over a network.
 Unlike NFS, which works at the file system level, iSCSI works at the block device level.
 
 In iSCSI terminology, the system that shares the storage is known as the _target_.
 The storage can be a physical disk, or an area representing multiple disks or a portion of a physical disk.
 For example, if the disk(s) are formatted with ZFS, a zvol can be created to use as the iSCSI storage.
 
 The clients which access the iSCSI storage are called _initiators_.
 To initiators, the storage available through iSCSI appears as a raw, unformatted disk known as a LUN.
 Device nodes for the disk appear in [.filename]#/dev/# and the device must be separately formatted and mounted.
 
 FreeBSD provides a native, kernel-based iSCSI target and initiator.
 This section describes how to configure a FreeBSD system as a target or an initiator.
 
 [[network-iscsi-target]]
 === Configuring an iSCSI Target
 
 To configure an iSCSI target, create the [.filename]#/etc/ctl.conf# configuration file, add a line to [.filename]#/etc/rc.conf# to make sure the man:ctld[8] daemon is automatically started at boot, and then start the daemon.
 
 The following is an example of a simple [.filename]#/etc/ctl.conf# configuration file.
 Refer to man:ctl.conf[5] for a more complete description of this file's available options.
 
 [.programlisting]
 ....
 portal-group pg0 {
 	discovery-auth-group no-authentication
 	listen 0.0.0.0
 	listen [::]
 }
 
 target iqn.2012-06.com.example:target0 {
 	auth-group no-authentication
 	portal-group pg0
 
 	lun 0 {
 		path /data/target0-0
 		size 4G
 	}
 }
 ....
 
 The first entry defines the `pg0` portal group.
 Portal groups define which network addresses the man:ctld[8] daemon will listen on.
 The `discovery-auth-group no-authentication` entry indicates that any initiator is allowed to perform iSCSI target discovery without authentication.
 Lines three and four configure man:ctld[8] to listen on all IPv4 (`listen 0.0.0.0`) and IPv6 (`listen [::]`) addresses on the default port of 3260.
 
 It is not necessary to define a portal group as there is a built-in portal group called `default`.
 In this case, the difference between `default` and `pg0` is that with `default`, target discovery is always denied, while with `pg0`, it is always allowed.
 
 The second entry defines a single target.
 Target has two possible meanings: a machine serving iSCSI or a named group of LUNs.
 This example uses the latter meaning, where `iqn.2012-06.com.example:target0` is the target name.
 This target name is suitable for testing purposes.
 For actual use, change `com.example` to the real domain name, reversed.
 The `2012-06` represents the year and month of acquiring control of that domain name, and `target0` can be any value.
 Any number of targets can be defined in this configuration file.
 
 The `auth-group no-authentication` line allows all initiators to connect to the specified target and `portal-group pg0` makes the target reachable through the `pg0` portal group.
 
 The next section defines the LUN.
 To the initiator, each LUN will be visible as a separate disk device.
 Multiple LUNs can be defined for each target.
 Each LUN is identified by a number, where LUN 0 is mandatory.
 The `path /data/target0-0` line defines the full path to a file or zvol backing the LUN.
 That path must exist before starting man:ctld[8].
 The second line is optional and specifies the size of the LUN.
 
 Next, to make sure the man:ctld[8] daemon is started at boot, add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 ctld_enable="YES"
 ....
 
 To start man:ctld[8] now, run this command:
 
 [source,shell]
 ....
 # service ctld start
 ....
 
 As the man:ctld[8] daemon is started, it reads [.filename]#/etc/ctl.conf#.
 If this file is edited after the daemon starts, use this command so that the changes take effect immediately:
 
 [source,shell]
 ....
 # service ctld reload
 ....
 
 
 ==== Authentication
 
 The previous example is inherently insecure as it uses no authentication, granting anyone full access to all targets.
 To require a username and password to access targets, modify the configuration as follows:
 
 [.programlisting]
 ....
 auth-group ag0 {
 	chap username1 secretsecret
 	chap username2 anothersecret
 }
 
 portal-group pg0 {
 	discovery-auth-group no-authentication
 	listen 0.0.0.0
 	listen [::]
 }
 
 target iqn.2012-06.com.example:target0 {
 	auth-group ag0
 	portal-group pg0
 	lun 0 {
 		path /data/target0-0
 		size 4G
 	}
 }
 ....
 
 The `auth-group` section defines username and password pairs.
 An initiator trying to connect to `iqn.2012-06.com.example:target0` must first specify a defined username and secret.
 However, target discovery is still permitted without authentication.
 To require target discovery authentication, set `discovery-auth-group` to a defined `auth-group` name instead of `no-authentication`.
 
 It is common to define a single exported target for every initiator.
 As a shorthand for the syntax above, the username and password can be specified directly in the target entry:
 
 [.programlisting]
 ....
 target iqn.2012-06.com.example:target0 {
 	portal-group pg0
 	chap username1 secretsecret
 
 	lun 0 {
 		path /data/target0-0
 		size 4G
 	}
 }
 ....
 
 
 [[network-iscsi-initiator]]
 === Configuring an iSCSI Initiator
 
 [NOTE]
 ====
 The iSCSI initiator described in this section is supported starting with FreeBSD 10.0-RELEASE.
 To use the iSCSI initiator available in older versions, refer to man:iscontrol[8].
 ====
 
 The iSCSI initiator requires that the man:iscsid[8] daemon is running.
 This daemon does not use a configuration file.
 To start it automatically at boot, add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 iscsid_enable="YES"
 ....
 
 To start man:iscsid[8] now, run this command:
 
 [source,shell]
 ....
 # service iscsid start
 ....
 
 Connecting to a target can be done with or without an [.filename]#/etc/iscsi.conf# configuration file.
 This section demonstrates both types of connections.
 
 ==== Connecting to a Target Without a Configuration File
 
 To connect an initiator to a single target, specify the IP address of the portal and the name of the target:
 
 [source,shell]
 ....
 # iscsictl -A -p 10.10.10.10 -t iqn.2012-06.com.example:target0
 ....
 
 To verify if the connection succeeded, run `iscsictl` without any arguments.
 The output should look similar to this:
 
 [.programlisting]
 ....
 Target name                                     Target portal   State
 iqn.2012-06.com.example:target0                 10.10.10.10     Connected: da0
 ....
 
 In this example, the iSCSI session was successfully established, with [.filename]#/dev/da0# representing the attached LUN.
 If the `iqn.2012-06.com.example:target0` target exports more than one LUN, multiple device nodes will be shown in that section of the output:
 
 [source,shell]
 ....
 Connected: da0 da1 da2.
 ....
 
 Any errors will be reported in the output, as well as the system logs.
 For example, this message usually means that the man:iscsid[8] daemon is not running:
 
 [.programlisting]
 ....
 Target name                                     Target portal   State
 iqn.2012-06.com.example:target0                 10.10.10.10     Waiting for iscsid(8)
 ....
 
 The following message suggests a networking problem, such as a wrong IP address or port:
 
 [.programlisting]
 ....
 Target name                                     Target portal   State
 iqn.2012-06.com.example:target0                 10.10.10.11     Connection refused
 ....
 
 This message means that the specified target name is wrong:
 
 [.programlisting]
 ....
 Target name                                     Target portal   State
 iqn.2012-06.com.example:target0                 10.10.10.10     Not found
 ....
 
 This message means that the target requires authentication:
 
 [.programlisting]
 ....
 Target name                                     Target portal   State
 iqn.2012-06.com.example:target0                 10.10.10.10     Authentication failed
 ....
 
 To specify a CHAP username and secret, use this syntax:
 
 [source,shell]
 ....
 # iscsictl -A -p 10.10.10.10 -t iqn.2012-06.com.example:target0 -u user -s secretsecret
 ....
 
 
 ==== Connecting to a Target with a Configuration File
 
 To connect using a configuration file, create [.filename]#/etc/iscsi.conf# with contents like this:
 
 [.programlisting]
 ....
 t0 {
 	TargetAddress   = 10.10.10.10
 	TargetName      = iqn.2012-06.com.example:target0
 	AuthMethod      = CHAP
 	chapIName       = user
 	chapSecret      = secretsecret
 }
 ....
 
 The `t0` specifies a nickname for the configuration file section.
 It will be used by the initiator to specify which configuration to use.
 The other lines specify the parameters to use during connection.
 The `TargetAddress` and `TargetName` are mandatory, whereas the other options are optional.
 In this example, the CHAP username and secret are shown.
 
 To connect to the defined target, specify the nickname:
 
 [source,shell]
 ....
 # iscsictl -An t0
 ....
 
 Alternately, to connect to all targets defined in the configuration file, use:
 
 [source,shell]
 ....
 # iscsictl -Aa
 ....
 
 To make the initiator automatically connect to all targets in [.filename]#/etc/iscsi.conf#, add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 iscsictl_enable="YES"
 iscsictl_flags="-Aa"
 ....
diff --git a/documentation/content/en/books/handbook/ports/_index.adoc b/documentation/content/en/books/handbook/ports/_index.adoc
index abb1380d72..310b9d3c35 100644
--- a/documentation/content/en/books/handbook/ports/_index.adoc
+++ b/documentation/content/en/books/handbook/ports/_index.adoc
@@ -1,1331 +1,1331 @@
 ---
 title: "Chapter 4. Installing Applications: Packages and Ports"
 part: Part I. Getting Started
 prev: books/handbook/basics
 next: books/handbook/x11
 description: "FreeBSD provides two complementary technologies for installing third-party software: the FreeBSD Ports Collection, for installing from source, and packages, for installing from pre-built binaries"
 tags: ["ports", "collection", "pkg", "poudriere", "management"]
 ---
 
 [[ports]]
 = Installing Applications: Packages and Ports
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 4
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/ports/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/ports/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/ports/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[ports-synopsis]]
 == Synopsis
 
 FreeBSD is bundled with a rich collection of system tools as part of the base system.
 In addition, FreeBSD provides two complementary technologies for installing third-party software: the FreeBSD Ports Collection,
 for installing from source, and packages, for installing from pre-built binaries.
 Either method may be used to install software from local media or from the network.
 
 After reading this chapter, you will know:
 
 * The difference between binary packages and ports.
 * How to find third-party software that has been ported to FreeBSD.
 * How to manage binary packages using pkg.
 * How to build third-party software from source using the Ports Collection.
 * How to find the files installed with the application for post-installation configuration.
 * What to do if a software installation fails.
 
 [[ports-overview]]
 == Overview of Software Installation
 
 The typical steps for installing third-party software on a UNIX(R) system include:
 
 [.procedure]
 . Find and download the software, which might be distributed in source code format or as a binary.
 . Unpack the software from its distribution format. This is typically a tarball compressed with a program such as man:compress[1], man:gzip[1], man:bzip2[1] or man:xz[1].
 . Locate the documentation in [.filename]#INSTALL#, [.filename]#README# or some file in a [.filename]#doc/# subdirectory and read up on how to install the software.
 . If the software was distributed in source format, compile it. This may involve editing a [.filename]#Makefile# or running a `configure` script.
 . Test and install the software.
 
 A FreeBSD _port_ is a collection of files designed to automate the process of compiling an application from source code.
 The files that comprise a port contain all the necessary information to automatically download, extract, patch, compile, and install the application.
 
 If the software has not already been adapted and tested on FreeBSD, the source code might need editing in order for it to install and run properly.
 
 However, over link:https://www.FreeBSD.org/ports/[{numports}] third-party applications have already been ported to FreeBSD.
 When feasible, these applications are made available for download as pre-compiled _packages_.
 
 Packages can be manipulated with the FreeBSD package management commands.
 
 Both packages and ports understand dependencies.
 If a package or port is used to install an application and a dependent library is not already installed, the library will automatically be installed first.
 
 A FreeBSD package contains pre-compiled copies of all the commands for an application, as well as any configuration files and documentation.
 A package can be manipulated with the man:pkg[8] commands, such as `pkg install`.
 
 While the two technologies are similar, packages and ports each have their own strengths.
 Select the technology that meets your requirements for installing a particular application.
 
 .Package Benefits
 * A compressed package tarball is typically smaller than the compressed tarball containing the source code for the application.
 * Packages do not require compilation time. For large applications, such as Mozilla, KDE, or GNOME, this can be important on a slow system.
 * Packages do not require any understanding of the process involved in compiling software on FreeBSD.
 
 .Port Benefits
 * Packages are normally compiled with conservative options because they have to run on the maximum number of systems. By compiling from the port, one can change the compilation options.
 * Some applications have compile-time options relating to which features are installed. For example, Apache can be configured with a wide variety of different built-in options.
-+ 
++
 In some cases, multiple packages will exist for the same application to specify certain settings. For example, Ghostscript is available as a [.filename]#ghostscript# package and a [.filename]#ghostscript-nox11# package, depending on whether or not Xorg is installed. Creating multiple packages rapidly becomes impossible if an application has more than one or two different compile-time options.
 * The licensing conditions of some software forbid binary distribution. Such software must be distributed as source code which must be compiled by the end-user.
 * Some people do not trust binary distributions or prefer to read through source code in order to look for potential problems.
 * Source code is needed in order to apply custom patches.
 
 To keep track of updated ports, subscribe to the {freebsd-ports} and the {freebsd-ports-bugs}.
 
 [WARNING]
 ====
 
 Before installing any application, check https://vuxml.freebsd.org/[] for security issues related to the application or type `pkg audit -F` to check all installed applications for known vulnerabilities.
 ====
 
 The remainder of this chapter explains how to use packages and ports to install and manage third-party software on FreeBSD.
 
 [[ports-finding-applications]]
 == Finding Software
 
 FreeBSD's list of available applications is growing all the time.
 There are a number of ways to find software to install:
 
 * The FreeBSD web site maintains an up-to-date searchable list of all the available applications, at link:https://www.FreeBSD.org/ports/[https://www.FreeBSD.org/ports/]. The ports can be searched by application name or by software category.
 * Dan Langille maintains http://www.FreshPorts.org/[FreshPorts.org] which provides a comprehensive search utility and also tracks changes to the applications in the Ports Collection. Registered users can create a customized watch list in order to receive an automated email when their watched ports are updated.
 * If finding a particular application becomes challenging, try searching a site like http://www.sourceforge.net/[SourceForge.net] or http://www.github.com/[GitHub.com] then check back at the link:https://www.FreeBSD.org/ports/[FreeBSD site] to see if the application has been ported.
 * To search the binary package repository for an application:
 +
 [source,shell]
 ....
 # pkg search subversion
 git-subversion-1.9.2
 java-subversion-1.8.8_2
 p5-subversion-1.8.8_2
 py27-hgsubversion-1.6
 py27-subversion-1.8.8_2
 ruby-subversion-1.8.8_2
 subversion-1.8.8_2
 subversion-book-4515
 subversion-static-1.8.8_2
 subversion16-1.6.23_4
 subversion17-1.7.16_2
 ....
-+ 
++
 Package names include the version number and, in the case of ports based on python, the version number of the version of python the package was built with.
 Some ports also have multiple versions available.
 In the case of Subversion, there are different versions available, as well as different compile options.
 In this case, the statically linked version of Subversion.
 When indicating which package to install, it is best to specify the application by the port origin, which is the path in the ports tree.
 Repeat the `pkg search` with `-o` to list the origin of each package:
 +
 [source,shell]
 ....
 # pkg search -o subversion
 devel/git-subversion
 java/java-subversion
 devel/p5-subversion
 devel/py-hgsubversion
 devel/py-subversion
 devel/ruby-subversion
 devel/subversion16
 devel/subversion17
 devel/subversion
 devel/subversion-book
 devel/subversion-static
 ....
-+ 
++
 Searching by shell globs, regular expressions, exact match, by description, or any other field in the repository database is also supported by `pkg search`.
 After installing package:ports-mgmt/pkg[] or package:ports-mgmt/pkg-devel[], see man:pkg-search[8] for more details.
 * If the Ports Collection is already installed, there are several methods to query the local version of the ports tree. To find out which category a port is in, type `whereis _file_`, where _file_ is the program to be installed:
 +
 [source,shell]
 ....
 # whereis lsof
 lsof: /usr/ports/sysutils/lsof
 ....
-+ 
++
 Alternately, an man:echo[1] statement can be used:
 +
 [source,shell]
 ....
 # echo /usr/ports/*/*lsof*
 /usr/ports/sysutils/lsof
 ....
-+ 
++
 Note that this will also return any matched files downloaded into the [.filename]#/usr/ports/distfiles# directory.
 * Another way to find software is by using the Ports Collection's built-in search mechanism. To use the search feature, cd to [.filename]#/usr/ports# then run `make search name=program-name` where _program-name_ is the name of the software. For example, to search for `lsof`:
 +
 [source,shell]
 ....
 # cd /usr/ports
 # make search name=lsof
 Port:   lsof-4.88.d,8
 Path:   /usr/ports/sysutils/lsof
 Info:   Lists information about open files (similar to fstat(1))
 Maint:  ler@lerctr.org
 Index:  sysutils
 B-deps:
 R-deps: 
 ....
 +
 [TIP]
 ====
 The built-in search mechanism uses a file of index information.
 If a message indicates that the [.filename]#INDEX# is required, run `make fetchindex` to download the current index file.
 With the [.filename]#INDEX# present, `make search` will be able to perform the requested search.
 ====
-+ 
++
 The "Path:" line indicates where to find the port.
-+ 
++
 To receive less information, use the `quicksearch` feature:
 +
 [source,shell]
 ....
 # cd /usr/ports
 # make quicksearch name=lsof
 Port:   lsof-4.88.d,8
 Path:   /usr/ports/sysutils/lsof
 Info:   Lists information about open files (similar to fstat(1))
 ....
-+ 
++
 For more in-depth searching, use `make search key=_string_` or `make quicksearch key=_string_`, where _string_ is some text to search for.
 The text can be in comments, descriptions, or dependencies in order to find ports which relate to a particular subject when the name of the program is unknown.
-+ 
++
 When using `search` or `quicksearch`, the search string is case-insensitive.
 Searching for "LSOF" will yield the same results as searching for "lsof".
 
 [[pkgng-intro]]
 == Using pkg for Binary Package Management
 
 pkg is the next generation replacement for the traditional FreeBSD package management tools, offering many features that make dealing with binary packages faster and easier.
 
 For sites wishing to only use prebuilt binary packages from the FreeBSD mirrors, managing packages with pkg can be sufficient.
 
 However, for those sites building from source or using their own repositories, a separate <<ports-upgrading-tools,port management tool>> will be needed.
 
 Since pkg only works with binary packages, it is not a replacement for such tools.
 Those tools can be used to install software from both binary packages and the Ports Collection, while pkg installs only binary packages.
 
 [[pkgng-initial-setup]]
 === Getting Started with pkg
 
 FreeBSD includes a bootstrap utility which can be used to download and install pkg and its manual pages.
 This utility is designed to work with versions of FreeBSD starting with 10._X_.
 
 [NOTE]
 ====
 Not all FreeBSD versions and architectures support this bootstrap process.
 The current list is at https://pkg.freebsd.org/[].
 For other cases, pkg must instead be installed from the Ports Collection or as a binary package.
 ====
 
 To bootstrap the system, run:
 
 [source,shell]
 ....
 # /usr/sbin/pkg
 ....
 
 You must have a working Internet connection for the bootstrap process to succeed.
 
 Otherwise, to install the port, run:
 
 [source,shell]
 ....
 # cd /usr/ports/ports-mgmt/pkg
 # make
 # make install clean
 ....
 
 When upgrading an existing system that originally used the older pkg_* tools,
 the database must be converted to the new format, so that the new tools are aware of the already installed packages.
 Once pkg has been installed, the package database must be converted from the traditional format to the new format by running this command:
 
 [source,shell]
 ....
 # pkg2ng
 ....
 
 [NOTE]
 ====
 This step is not required for new installations that do not yet have any third-party software installed.
 ====
 
 [IMPORTANT]
 ====
 This step is not reversible.
 Once the package database has been converted to the pkg format, the traditional `pkg_*` tools should no longer be used.
 ====
 
 [NOTE]
 ====
 The package database conversion may emit errors as the contents are converted to the new version.
 Generally, these errors can be safely ignored.
 However, a list of software that was not successfully converted is shown after `pkg2ng` finishes.
 These applications must be manually reinstalled.
 ====
 
 To ensure that the Ports Collection registers new software with pkg instead of the traditional packages database,
 FreeBSD versions earlier than 10._X_ require this line in [.filename]#/etc/make.conf#:
 
 [.programlisting]
 ....
 WITH_PKGNG=   yes
 ....
 
 By default, pkg uses the binary packages from the FreeBSD package mirrors (the _repository_).
 For information about building a custom package repository, see <<ports-poudriere>>.
 
 Additional pkg configuration options are described in man:pkg.conf[5].
 
 Usage information for pkg is available in the man:pkg[8] manual page or by running `pkg` without additional arguments.
 
 Each pkg command argument is documented in a command-specific manual page.
 To read the manual page for `pkg install`, for example, run either of these commands:
 
 [source,shell]
 ....
 # pkg help install
 ....
 
 [source,shell]
 ....
 # man pkg-install
 ....
 
 The rest of this section demonstrates common binary package management tasks which can be performed using pkg.
 Each demonstrated command provides many switches to customize its use.
 Refer to a command's help or man page for details and more examples.
 
 [[quarterly-latest-branch]]
 === Quarterly and Latest Ports Branches
 
 The `Quarterly` branch provides users with a more predictable and stable experience for port and package installation and upgrades.
 This is done essentially by only allowing non-feature updates.
 Quarterly branches aim to receive security fixes (that may be version updates, or backports of commits), bug fixes and ports compliance or framework changes.
 The Quarterly branch is cut from HEAD at the beginning of every (yearly) quarter in January, April, July, and October.
 Branches are named according to the year (YYYY) and quarter (Q1-4) they are created in.
 For example, the quarterly branch created in January 2016, is named 2016Q1.
 And the `Latest` branch provides the latest versions of the packages to the users.
 
 To switch from quarterly to latest run the following commands:
 
 [source,shell]
 ....
 # mkdir -p /usr/local/etc/pkg/repos
 # cp /etc/pkg/FreeBSD.conf /usr/local/etc/pkg/repos/FreeBSD.conf
 ....
 
 Edit the file [.filename]#/usr/local/etc/pkg/repos/FreeBSD.conf# and change the string _quarterly_ to _latest_ in the `url:` line.
 
 The result should be similar to the following:
 
 [.programlisting]
 ....
 FreeBSD: {
   url: "pkg+http://pkg.FreeBSD.org/${ABI}/latest",
   mirror_type: "srv",
   signature_type: "fingerprints",
   fingerprints: "/usr/share/keys/pkg",
   enabled: yes
 }
 ....
 
 And finally run this command to update from the new (latest) repository metadata.
 
 [source,shell]
 ....
 # pkg update -f
 ....
 
 [[pkgng-pkg-info]]
 === Obtaining Information About Installed Packages
 
 Information about the packages installed on a system can be viewed by running `pkg info` which, when run without any switches,
 will list the package version for either all installed packages or the specified package.
 
 For example, to see which version of pkg is installed, run:
 
 [source,shell]
 ....
 # pkg info pkg
 pkg-1.1.4_1
 ....
 
 [[pkgng-installing-deinstalling]]
 === Installing and Removing Packages
 
 To install a binary package use the following command, where _packagename_ is the name of the package to install:
 
 [source,shell]
 ....
 # pkg install packagename
 ....
 
 This command uses repository data to determine which version of the software to install and if it has any uninstalled dependencies.
 For example, to install curl:
 
 [source,shell]
 ....
 # pkg install curl
 Updating repository catalogue
 /usr/local/tmp/All/curl-7.31.0_1.txz          100% of 1181 kB 1380 kBps 00m01s
 
 /usr/local/tmp/All/ca_root_nss-3.15.1_1.txz   100% of  288 kB 1700 kBps 00m00s
 
 Updating repository catalogue
 The following 2 packages will be installed:
 
         Installing ca_root_nss: 3.15.1_1
         Installing curl: 7.31.0_1
 
 The installation will require 3 MB more space
 
 0 B to be downloaded
 
 Proceed with installing packages [y/N]: y
 Checking integrity... done
 [1/2] Installing ca_root_nss-3.15.1_1... done
 [2/2] Installing curl-7.31.0_1... done
 Cleaning up cache files...Done
 ....
 
 The new package and any additional packages that were installed as dependencies can be seen in the installed packages list:
 
 [source,shell]
 ....
 # pkg info
 ca_root_nss-3.15.1_1	The root certificate bundle from the Mozilla Project
 curl-7.31.0_1	Non-interactive tool to get files from FTP, GOPHER, HTTP(S) servers
 pkg-1.1.4_6	New generation package manager
 ....
 
 Packages that are no longer needed can be removed with `pkg delete`.
 For example:
 
 [source,shell]
 ....
 # pkg delete curl
 The following packages will be deleted:
 
 	curl-7.31.0_1
 
 The deletion will free 3 MB
 
 Proceed with deleting packages [y/N]: y
 [1/1] Deleting curl-7.31.0_1... done
 ....
 
 [[pkgng-upgrading]]
 === Upgrading Installed Packages
 
 Installed packages can be upgraded to their latest versions by running:
 
 [source,shell]
 ....
 # pkg upgrade
 ....
 
 This command will compare the installed versions with those available in the repository catalogue and upgrade them from the repository.
 
 [[pkgng-auditing]]
 === Auditing Installed Packages
 
 Software vulnerabilities are regularly discovered in third-party applications.
 To address this, pkg includes a built-in auditing mechanism.
 To determine if there are any known vulnerabilities for the software installed on the system, run:
 
 [source,shell]
 ....
 # pkg audit -F
 ....
 
 [[pkgng-autoremove]]
 === Automatically Removing Unused Packages
 
 Removing a package may leave behind dependencies which are no longer required.
 Unneeded packages that were installed as dependencies (leaf packages) can be automatically detected and removed using:
 
 [source,shell]
 ....
 # pkg autoremove
 Packages to be autoremoved:
 	ca_root_nss-3.15.1_1
 
 The autoremoval will free 723 kB
 
 Proceed with autoremoval of packages [y/N]: y
 Deinstalling ca_root_nss-3.15.1_1... done
 ....
 
 Packages installed as dependencies are called _automatic_ packages.
 Non-automatic packages, i.e the packages that were explicity installed not as a dependency to another package, can be listed using:
 
 [source,shell]
 ....
 # pkg prime-list
 nginx
 openvpn
 sudo
 ....
 
 `pkg prime-list` is an alias command declared in [.filename]#/usr/local/etc/pkg.conf#.
 There are many others that can be used to query the package database of the system.
 For instance, command `pkg prime-origins` can be used to get the origin port directory of the list mentioned above:
 
 [source,shell]
 ....
 # pkg prime-origins
 www/nginx
 security/openvpn
 security/sudo
 ....
 
 This list can be used to rebuild all packages installed on a system using build tools such as package:ports-mgmt/poudriere[] or package:ports-mgmt/synth[].
 
 Marking an installed package as automatic can be done using:
 
 [source,shell]
 ....
 # pkg set -A 1 devel/cmake
 ....
 
 Once a package is a leaf package and is marked as automatic, it gets selected by `pkg autoremove`.
 
 Marking an installed package as _not_ automatic can be done using:
 
 [source,shell]
 ....
 # pkg set -A 0 devel/cmake
 ....
 
 [[pkgng-backup]]
 === Restoring the Package Database
 
 Unlike the traditional package management system, pkg includes its own package database backup mechanism.
 This functionality is enabled by default.
 
 [TIP]
 ====
 To disable the periodic script from backing up the package database, set `daily_backup_pkgdb_enable="NO"` in man:periodic.conf[5].
 ====
 
 To restore the contents of a previous package database backup,
 run the following command replacing _/path/to/pkg.sql_ with the location of the backup:
 
 [source,shell]
 ....
 # pkg backup -r /path/to/pkg.sql
 ....
 
 [NOTE]
 ====
 If restoring a backup taken by the periodic script, it must be decompressed prior to being restored.
 ====
 
 To run a manual backup of the pkg database, run the following command,
 replacing _/path/to/pkg.sql_ with a suitable file name and location:
 
 [source,shell]
 ....
 # pkg backup -d /path/to/pkg.sql
 ....
 
 [[pkgng-clean]]
 === Removing Stale Packages
 
 By default, pkg stores binary packages in a cache directory defined by `PKG_CACHEDIR` in man:pkg.conf[5].
 Only copies of the latest installed packages are kept. Older versions of pkg kept all previous packages.
 To remove these outdated binary packages, run:
 
 [source,shell]
 ....
 # pkg clean
 ....
 
 The entire cache may be cleared by running:
 
 [source,shell]
 ....
 # pkg clean -a
 ....
 
 [[pkgng-set]]
 === Modifying Package Metadata
 
 Software within the FreeBSD Ports Collection can undergo major version number changes.
 To address this, pkg has a built-in command to update package origins.
 This can be useful, for example, if package:lang/php5[] is renamed to package:lang/php53[] so that package:lang/php5[] can now represent version `5.4`.
 
 To change the package origin for the above example, run:
 
 [source,shell]
 ....
 # pkg set -o lang/php5:lang/php53
 ....
 
 As another example, to update package:lang/ruby18[] to package:lang/ruby19[], run:
 
 [source,shell]
 ....
 # pkg set -o lang/ruby18:lang/ruby19
 ....
 
 As a final example, to change the origin of the [.filename]#libglut# shared libraries from package:graphics/libglut[] to package:graphics/freeglut[], run:
 
 [source,shell]
 ....
 # pkg set -o graphics/libglut:graphics/freeglut
 ....
 
 [NOTE]
 ====
 When changing package origins, it is important to reinstall packages that are dependent on the package with the modified origin.
 To force a reinstallation of dependent packages, run:
 
 [source,shell]
 ....
 # pkg install -Rf graphics/freeglut
 ....
 
 ====
 
 [[ports-using]]
 == Using the Ports Collection
 
 The Ports Collection is a set of [.filename]##Makefile##s, patches, and description files.
 Each set of these files is used to compile and install an individual application on FreeBSD, and is called a _port_.
 
 By default, the Ports Collection itself is stored as a subdirectory of [.filename]#/usr/ports#.
 
 [WARNING]
 ====
 Before installing and using the Ports Collection, please be aware that it is generally ill-advised to use the Ports Collection in conjunction with the binary packages provided via pkg to install software.
 pkg, by default, tracks quarterly branch-releases of the ports tree and not HEAD.
 Dependencies could be different for a port in HEAD compared to its counterpart in a quarterly branch release and this could result in conflicts between dependencies installed by pkg and those from the Ports Collection.
 If the Ports Collection and pkg must be used in conjunction, then be sure that your Ports Collection and pkg are on the same branch release of the ports tree.
 ====
 
 The Ports Collection contains directories for software categories.
 Inside each category are subdirectories for individual applications.
 Each application subdirectory contains a set of files that tells FreeBSD how to compile and install that program, called a _ports skeleton_.
 Each port skeleton includes these files and directories:
 
 * [.filename]#Makefile#: contains statements that specify how the application should be compiled and where its components should be installed.
 * [.filename]#distinfo#: contains the names and checksums of the files that must be downloaded to build the port.
 * [.filename]#files/#: this directory contains any patches needed for the program to compile and install on FreeBSD. This directory may also contain other files used to build the port.
 * [.filename]#pkg-descr#: provides a more detailed description of the program.
 * [.filename]#pkg-plist#: a list of all the files that will be installed by the port. It also tells the ports system which files to remove upon deinstallation.
 
 Some ports include [.filename]#pkg-message# or other files to handle special situations.
 For more details on these files, and on ports in general, refer to the link:{porters-handbook}[FreeBSD Porter's Handbook].
 
 The port does not include the actual source code, also known as a [.filename]#distfile#.
 The extract portion of building a port will automatically save the downloaded source to [.filename]#/usr/ports/distfiles#.
 
 [[ports-using-installation-methods]]
 === Installing the Ports Collection
 
 Before an application can be compiled using a port, the Ports Collection must first be installed.
 If it was not installed during the installation of FreeBSD, use one of the following methods to install it:
 
 [[ports-using-portsnap-method]]
 [.procedure]
 ****
 *Procedure: Portsnap Method*
 
 The base system of FreeBSD includes Portsnap.
 This is a fast and user-friendly tool for retrieving the Ports Collection and is the recommended choice for most users not running FreeBSD-CURRENT.
 This utility connects to a FreeBSD site, verifies the secure key, and downloads a new copy of the Ports Collection.
 The key is used to verify the integrity of all downloaded files.
 
 . To download a compressed snapshot of the Ports Collection into [.filename]#/var/db/portsnap#:
 +
 [source,shell]
 ....
 # portsnap fetch
 ....
 +
 . When running Portsnap for the first time, extract the snapshot into [.filename]#/usr/ports#:
 +
 [source,shell]
 ....
 # portsnap extract
 ....
 +
 . After the first use of Portsnap has been completed as shown above, [.filename]#/usr/ports# can be updated as needed by running:
 +
 [source,shell]
 ....
 # portsnap fetch
 # portsnap update
 ....
 +
 When using `fetch`, the `extract` or the `update` operation may be run consecutively, like so:
 +
 [source,shell]
 ....
 # portsnap fetch update
 ....
 ****
 
 [[ports-using-git-method]]
 [.procedure]
 ****
 *Procedure: Git Method*
 
 If more control over the ports tree is needed or if local changes need to be maintained, or if running FreeBSD-CURRENT,
 Git can be used to obtain the Ports Collection.
 Refer to link:{committers-guide}#git-primer[the Git Primer] for a detailed description of Git.
 
 . Git must be installed before it can be used to check out the ports tree. If a copy of the ports tree is already present, install Git like this:
 +
 [source,shell]
 ....
 # cd /usr/ports/devel/git
 # make install clean
 ....
-+ 
++
 If the ports tree is not available, or pkg is being used to manage packages, Git can be installed as a package:
 +
 [source,shell]
 ....
 # pkg install git
 ....
 +
 . Check out a copy of the HEAD branch of the ports tree:
 +
 [source,shell]
 ....
 # git clone https://git.FreeBSD.org/ports.git /usr/ports
 ....
 +
 . Or, check out a copy of a quarterly branch:
 +
 [source,shell]
 ....
 # git clone https://git.FreeBSD.org/ports.git -b 2020Q3 /usr/ports
 ....
 +
 . As needed, update [.filename]#/usr/ports# after the initial Git checkout:
 +
 [source,shell]
 ....
 # git -C /usr/ports pull
 ....
 +
 . As needed, switch [.filename]#/usr/ports# to a different quarterly branch:
 +
 [source,shell]
 ....
 # git -C /usr/ports switch 2020Q4
 ....
 ****
 
 === Installing Ports
 
 This section provides basic instructions on using the Ports Collection to install or remove software.
 The detailed description of available `make` targets and environment variables is available in man:ports[7].
 
 [WARNING]
 ====
 
 Before compiling any port, be sure to update the Ports Collection as described in the previous section.
 Since the installation of any third-party software can introduce security vulnerabilities, it is recommended to first check https://vuxml.freebsd.org/[] for known security issues related to the port.
 Alternately, run `pkg audit -F` before installing a new port.
 This command can be configured to automatically perform a security audit and an update of the vulnerability database during the daily security system check. For more information, refer to man:pkg-audit[8] and man:periodic[8].
 ====
 
 Using the Ports Collection assumes a working Internet connection.
 It also requires superuser privilege.
 
 To compile and install the port, change to the directory of the port to be installed, then type `make install` at the prompt.
 Messages will indicate the progress:
 
 [source,shell]
 ....
 # cd /usr/ports/sysutils/lsof
 # make install
 >> lsof_4.88D.freebsd.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 >> Attempting to fetch from ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/.
 ===>  Extracting for lsof-4.88
 ...
 [extraction output snipped]
 ...
 >> Checksum OK for lsof_4.88D.freebsd.tar.gz.
 ===>  Patching for lsof-4.88.d,8
 ===>  Applying FreeBSD patches for lsof-4.88.d,8
 ===>  Configuring for lsof-4.88.d,8
 ...
 [configure output snipped]
 ...
 ===>  Building for lsof-4.88.d,8
 ...
 [compilation output snipped]
 ...
 
 ===>  Installing for lsof-4.88.d,8
 ...
 [installation output snipped]
 ...
 ===>   Generating temporary packing list
 ===>   Compressing manual pages for lsof-4.88.d,8
 ===>   Registering installation for lsof-4.88.d,8
 ===>  SECURITY NOTE:
       This port has installed the following binaries which execute with
       increased privileges.
 /usr/local/sbin/lsof
 #
 ....
 
 Since `lsof` is a program that runs with increased privileges, a security warning is displayed as it is installed.
 Once the installation is complete, the prompt will be returned.
 
 Some shells keep a cache of the commands that are available in the directories listed in the `PATH` environment variable, to speed up lookup operations for the executable file of these commands.
 Users of the `tcsh` shell should type `rehash` so that a newly installed command can be used without specifying its full path.
 Use `hash -r` instead for the `sh` shell.
 Refer to the documentation for the shell for more information.
 
 During installation, a working subdirectory is created which contains all the temporary files used during compilation.
 Removing this directory saves disk space and minimizes the chance of problems later when upgrading to the newer version of the port:
 
 [source,shell]
 ....
 # make clean
 ===>  Cleaning for lsof-88.d,8
 #
 ....
 
 [NOTE]
 ====
 To save this extra step, instead use `make install clean` when compiling the port.
 ====
 
 ==== Customizing Ports Installation
 
 Some ports provide build options which can be used to enable or disable application components, provide security options, or allow for other customizations.
 Examples include package:www/firefox[], package:security/gpgme[], and package:mail/sylpheed-claws[].
 If the port depends upon other ports which have configurable options,
 it may pause several times for user interaction as the default behavior is to prompt the user to select options from a menu.
 To avoid this and do all of the configuration in one batch, run `make config-recursive` within the port skeleton.
 Then, run `make install [clean]` to compile and install the port.
 
 [TIP]
 ====
 When using `config-recursive`, the list of ports to configure are gathered by the `all-depends-list` target.
 It is recommended to run `make config-recursive` until all dependent ports options have been defined,
 and ports options screens no longer appear, to be certain that all dependency options have been configured.
 ====
 
 There are several ways to revisit a port's build options menu in order to add, remove, or change these options after a port has been built.
 One method is to `cd` into the directory containing the port and type `make config`.
 Another option is to use `make showconfig`.
 Another option is to execute `make rmconfig` which will remove all selected options and allow you to start over.
 All of these options, and others, are explained in great detail in man:ports[7].
 
 The ports system uses man:fetch[1] to download the source files, which supports various environment variables.
 The `FTP_PASSIVE_MODE`, `FTP_PROXY`, and `FTP_PASSWORD` variables may need to be set if the FreeBSD system is behind a firewall or FTP/HTTP proxy.
 See man:fetch[3] for the complete list of supported variables.
 
 For users who cannot be connected to the Internet all the time, `make fetch` can be run within [.filename]#/usr/ports#,
 to fetch all distfiles, or within a category, such as [.filename]#/usr/ports/net#, or within the specific port skeleton.
 Note that if a port has any dependencies, running this command in a category or ports skeleton will _not_ fetch the distfiles of ports from another category.
 Instead, use `make fetch-recursive` to also fetch the distfiles for all the dependencies of a port.
 
 In rare cases, such as when an organization has a local distfiles repository, the `MASTER_SITES` variable can be used to override the download locations specified in the [.filename]#Makefile#.
 When using, specify the alternate location:
 
 [source,shell]
 ....
 # cd /usr/ports/directory
 # make MASTER_SITE_OVERRIDE= \
 ftp://ftp.organization.org/pub/FreeBSD/ports/distfiles/ fetch
 ....
 
 The `WRKDIRPREFIX` and `PREFIX` variables can override the default working and target directories. For example:
 
 [source,shell]
 ....
 # make WRKDIRPREFIX=/usr/home/example/ports install
 ....
 
 will compile the port in [.filename]#/usr/home/example/ports# and install everything under [.filename]#/usr/local#.
 
 [source,shell]
 ....
 # make PREFIX=/usr/home/example/local install
 ....
 
 will compile the port in [.filename]#/usr/ports# and install it in [.filename]#/usr/home/example/local#. And:
 
 [source,shell]
 ....
 # make WRKDIRPREFIX=../ports PREFIX=../local install
 ....
 
 will combine the two.
 
 These can also be set as environmental variables.
 Refer to the manual page for your shell for instructions on how to set an environmental variable.
 
 [[ports-removing]]
 === Removing Installed Ports
 
 Installed ports can be uninstalled using `pkg delete`.
 Examples for using this command can be found in the man:pkg-delete[8] manual page.
 
 Alternately, `make deinstall` can be run in the port's directory:
 
 [source,shell]
 ....
 # cd /usr/ports/sysutils/lsof
 # make deinstall
 ===>  Deinstalling for sysutils/lsof
 ===>   Deinstalling
 Deinstallation has been requested for the following 1 packages:
 
 	lsof-4.88.d,8
 
 The deinstallation will free 229 kB
 [1/1] Deleting lsof-4.88.d,8... done
 ....
 
 It is recommended to read the messages as the port is uninstalled.
 If the port has any applications that depend upon it, this information will be displayed but the uninstallation will proceed.
 In such cases, it may be better to reinstall the application in order to prevent broken dependencies.
 
 [[ports-upgrading]]
 === Upgrading Ports
 
 Over time, newer versions of software become available in the Ports Collection.
 This section describes how to determine which software can be upgraded and how to perform the upgrade.
 
 To determine if newer versions of installed ports are available, ensure that the latest version of the ports tree is installed,
 using the updating command described in either <<ports-using-portsnap-method, “Portsnap Method”>> or <<ports-using-git-method, “Git Method”>>.
 On FreeBSD 10 and later, or if the system has been converted to pkg, the following command will list the installed ports which are out of date:
 
 [source,shell]
 ....
 # pkg version -l "<"
 ....
 
 For FreeBSD 9._X_ and lower, the following command will list the installed ports that are out of date:
 
 [source,shell]
 ....
 # pkg_version -l "<"
 ....
 
 [IMPORTANT]
 ====
 Before attempting an upgrade, read [.filename]#/usr/ports/UPDATING# from the top of the file to the date closest to the last time ports were upgraded or the system was installed.
 This file describes various issues and additional steps users may encounter and need to perform when updating a port, including such things as file format changes, changes in locations of configuration files, or any incompatibilities with previous versions.
 Make note of any instructions which match any of the ports that need upgrading and follow these instructions when performing the upgrade.
 ====
 
 [[ports-upgrading-tools]]
 ==== Tools to Upgrade and Manage Ports
 
 The Ports Collection contains several utilities to perform the actual upgrade.
 Each has its strengths and weaknesses.
 
 Historically, most installations used either Portmaster or Portupgrade.
 Synth is a newer alternative.
 
 [NOTE]
 ====
 The choice of which tool is best for a particular system is up to the system administrator.
 It is recommended practice to back up your data before using any of these tools.
 ====
 
 [[portmaster]]
 ==== Upgrading Ports Using Portmaster
 
 package:ports-mgmt/portmaster[] is a very small utility for upgrading installed ports.
 It is designed to use the tools installed with the FreeBSD base system without depending on other ports or databases.
 To install this utility as a port:
 
 [source,shell]
 ....
 # cd /usr/ports/ports-mgmt/portmaster
 # make install clean
 ....
 
 Portmaster defines four categories of ports:
 
 * Root port: has no dependencies and is not a dependency of any other ports.
 * Trunk port: has no dependencies, but other ports depend upon it.
 * Branch port: has dependencies and other ports depend upon it.
 * Leaf port: has dependencies but no other ports depend upon it.
 
 To list these categories and search for updates:
 
 [source,shell]
 ....
 # portmaster -L
 ===>>> Root ports (No dependencies, not depended on)
 ===>>> ispell-3.2.06_18
 ===>>> screen-4.0.3
         ===>>> New version available: screen-4.0.3_1
 ===>>> tcpflow-0.21_1
 ===>>> 7 root ports
 ...
 ===>>> Branch ports (Have dependencies, are depended on)
 ===>>> apache22-2.2.3
         ===>>> New version available: apache22-2.2.8
 ...
 ===>>> Leaf ports (Have dependencies, not depended on)
 ===>>> automake-1.9.6_2
 ===>>> bash-3.1.17
         ===>>> New version available: bash-3.2.33
 ...
 ===>>> 32 leaf ports
 
 ===>>> 137 total installed ports
         ===>>> 83 have new versions available
 ....
 
 This command is used to upgrade all outdated ports:
 
 [source,shell]
 ....
 # portmaster -a
 ....
 
 [NOTE]
 ====
 By default, Portmaster makes a backup package before deleting the existing port.
 If the installation of the new version is successful, Portmaster deletes the backup.
 Using `-b` instructs Portmaster not to automatically delete the backup.
 Adding `-i` starts Portmaster in interactive mode, prompting for confirmation before upgrading each port.
 Many other options are available.
 Read through the manual page for man:portmaster[8] for details regarding their usage.
 ====
 
 If errors are encountered during the upgrade process, add `-f` to upgrade and rebuild all ports:
 
 [source,shell]
 ....
 # portmaster -af
 ....
 
 Portmaster can also be used to install new ports on the system, upgrading all dependencies before building and installing the new port.
 To use this function, specify the location of the port in the Ports Collection:
 
 [source,shell]
 ....
 # portmaster shells/bash
 ....
 
 More information about package:ports-mgmt/portmaster[] may be found in its [.filename]#pkg-descr#.
 
 [[portupgrade]]
 ==== Upgrading Ports Using Portupgrade
 
 package:ports-mgmt/portupgrade[] is another utility that can be used to upgrade ports.
 It installs a suite of applications which can be used to manage ports.
 However, it is dependent upon Ruby. To install the port:
 
 [source,shell]
 ....
 # cd /usr/ports/ports-mgmt/portupgrade
 # make install clean
 ....
 
 Before performing an upgrade using this utility, it is recommended to scan the list of installed ports using `pkgdb -F` and to fix all the inconsistencies it reports.
 
 To upgrade all the outdated ports installed on the system, use `portupgrade -a`.
 Alternately, include `-i` to be asked for confirmation of every individual upgrade:
 
 [source,shell]
 ....
 # portupgrade -ai
 ....
 
 To upgrade only a specified application instead of all available ports, use `portupgrade _pkgname_`.
 It is very important to include `-R` to first upgrade all the ports required by the given application:
 
 [source,shell]
 ....
 # portupgrade -R firefox
 ....
 
 If `-P` is included, Portupgrade searches for available packages in the local directories listed in `PKG_PATH`.
 If none are available locally, it then fetches packages from a remote site.
 If packages can not be found locally or fetched remotely, Portupgrade will use ports.
 To avoid using ports entirely, specify `-PP`.
 This last set of options tells Portupgrade to abort if no packages are available:
 
 [source,shell]
 ....
 # portupgrade -PP gnome3
 ....
 
 To just fetch the port distfiles, or packages, if `-P` is specified, without building or installing anything, use `-F`.
 For further information on all of the available switches, refer to the manual page for `portupgrade`.
 
 More information about package:ports-mgmt/portupgrade[] may be found in its [.filename]#pkg-descr#.
 
 [[ports-disk-space]]
 === Ports and Disk Space
 
 Using the Ports Collection will use up disk space over time.
 After building and installing a port, running `make clean` within the ports skeleton will clean up the temporary [.filename]#work# directory.
 If Portmaster is used to install a port, it will automatically remove this directory unless `-K` is specified.
 If Portupgrade is installed, this command will remove all [.filename]#work# directories found within the local copy of the Ports Collection:
 
 [source,shell]
 ....
 # portsclean -C
 ....
 
 In addition, outdated source distribution files accumulate in [.filename]#/usr/ports/distfiles# over time.
 To use Portupgrade to delete all the distfiles that are no longer referenced by any ports:
 
 [source,shell]
 ....
 # portsclean -D
 ....
 
 Portupgrade can remove all distfiles not referenced by any port currently installed on the system:
 
 [source,shell]
 ....
 # portsclean -DD
 ....
 
 If Portmaster is installed, use:
 
 [source,shell]
 ....
 # portmaster --clean-distfiles
 ....
 
 By default, this command is interactive and prompts the user to confirm if a distfile should be deleted.
 
 In addition to these commands, package:ports-mgmt/pkg_cutleaves[] automates the task of removing installed ports that are no longer needed.
 
 [[ports-poudriere]]
 == Building Packages with Poudriere
 
 Poudriere is a `BSD`-licensed utility for creating and testing FreeBSD packages.
 It uses FreeBSD jails to set up isolated compilation environments.
 These jails can be used to build packages for versions of FreeBSD that are different from the system on which it is installed, and also to build packages for i386 if the host is an amd64 system.
 Once the packages are built, they are in a layout identical to the official mirrors.
 These packages are usable by man:pkg[8] and other package management tools.
 
 Poudriere is installed using the package:ports-mgmt/poudriere[] package or port.
 The installation includes a sample configuration file [.filename]#/usr/local/etc/poudriere.conf.sample#.
 Copy this file to [.filename]#/usr/local/etc/poudriere.conf#.
 Edit the copied file to suit the local configuration.
 
 While `ZFS` is not required on the system running poudriere, it is beneficial.
 When `ZFS` is used, `ZPOOL` must be specified in [.filename]#/usr/local/etc/poudriere.conf# and `FREEBSD_HOST` should be set to a nearby mirror.
 Defining `CCACHE_DIR` enables the use of package:devel/ccache[] to cache compilation and reduce build times for frequently-compiled code.
 It may be convenient to put poudriere datasets in an isolated tree mounted at [.filename]#/poudriere#.
 Defaults for the other configuration values are adequate.
 
 The number of processor cores detected is used to define how many builds will run in parallel.
 Supply enough virtual memory, either with `RAM` or swap space.
 If virtual memory runs out, the compilation jails will stop and be torn down, resulting in weird error messages.
 
 [[poudriere-initialization]]
 === Initialize Jails and Port Trees
 
 After configuration, initialize poudriere so that it installs a jail with the required FreeBSD tree and a ports tree.
 Specify a name for the jail using `-j` and the FreeBSD version with `-v`.
 On systems running FreeBSD/amd64, the architecture can be set with `-a` to either `i386` or `amd64`.
 The default is the architecture shown by `uname`.
 
 [source,shell]
 ....
 # poudriere jail -c -j 11amd64 -v 11.4-RELEASE
 [00:00:00] Creating 11amd64 fs at /poudriere/jails/11amd64... done
 [00:00:00] Using pre-distributed MANIFEST for FreeBSD 11.4-RELEASE amd64
 [00:00:00] Fetching base for FreeBSD 11.4-RELEASE amd64
 /poudriere/jails/11amd64/fromftp/base.txz              125 MB 4110 kBps    31s
 [00:00:33] Extracting base... done
 [00:00:54] Fetching src for FreeBSD 11.4-RELEASE amd64
 /poudriere/jails/11amd64/fromftp/src.txz               154 MB 4178 kBps    38s
 [00:01:33] Extracting src... done
 [00:02:31] Fetching lib32 for FreeBSD 11.4-RELEASE amd64
 /poudriere/jails/11amd64/fromftp/lib32.txz              24 MB 3969 kBps    06s
 [00:02:38] Extracting lib32... done
 [00:02:42] Cleaning up... done
 [00:02:42] Recording filesystem state for clean... done
 [00:02:42] Upgrading using ftp
 /etc/resolv.conf -> /poudriere/jails/11amd64/etc/resolv.conf
 Looking up update.FreeBSD.org mirrors... 3 mirrors found.
 Fetching public key from update4.freebsd.org... done.
 Fetching metadata signature for 11.4-RELEASE from update4.freebsd.org... done.
 Fetching metadata index... done.
 Fetching 2 metadata files... done.
 Inspecting system... done.
 Preparing to download files... done.
 Fetching 124 patches.....10....20....30....40....50....60....70....80....90....100....110....120.. done.
 Applying patches... done.
 Fetching 6 files... done.
 The following files will be added as part of updating to
 11.4-RELEASE-p1:
 /usr/src/contrib/unbound/.github
 /usr/src/contrib/unbound/.github/FUNDING.yml
 /usr/src/contrib/unbound/contrib/drop2rpz
 /usr/src/contrib/unbound/contrib/unbound_portable.service.in
 /usr/src/contrib/unbound/services/rpz.c
 /usr/src/contrib/unbound/services/rpz.h
 /usr/src/lib/libc/tests/gen/spawnp_enoexec.sh
 The following files will be updated as part of updating to
 11.4-RELEASE-p1:
 […]
 Installing updates...Scanning //usr/share/certs/blacklisted for certificates...
 Scanning //usr/share/certs/trusted for certificates...
  done.
 11.4-RELEASE-p1
 [00:04:06] Recording filesystem state for clean... done
 [00:04:07] Jail 11amd64 11.4-RELEASE-p1 amd64 is ready to be used
 ....
 
 [source,shell]
 ....
 # poudriere ports -c -p local -m git+https
 [00:00:00] Creating local fs at /poudriere/ports/local... done
 [00:00:00] Checking out the ports tree... done
 ....
 
 On a single computer, poudriere can build ports with multiple configurations, in multiple jails, and from different port trees.
 Custom configurations for these combinations are called _sets_.
 See the CUSTOMIZATION section of man:poudriere[8] for details after package:ports-mgmt/poudriere[] or package:ports-mgmt/poudriere-devel[] is installed.
 
 The basic configuration shown here puts a single jail-, port-, and set-specific [.filename]#make.conf# in [.filename]#/usr/local/etc/poudriere.d#.
 The filename in this example is created by combining the jail name, port name, and set name: [.filename]#11amd64-local-workstation-make.conf#.
 The system [.filename]#make.conf# and this new file are combined at build time to create the [.filename]#make.conf# used by the build jail.
 
 Packages to be built are entered in [.filename]#11amd64-local-workstation-pkglist#:
 
 [.programlisting]
 ....
 editors/emacs
 devel/git
 ports-mgmt/pkg
 ...
 ....
 
 Options and dependencies for the specified ports are configured:
 
 [source,shell]
 ....
 # poudriere options -j 11amd64 -p local -z workstation -f 11amd64-local-workstation-pkglist
 ....
 
 Finally, packages are built and a package repository is created:
 
 [source,shell]
 ....
 # poudriere bulk -j 11amd64 -p local -z workstation -f 11amd64-local-workstation-pkglist
 ....
 
 While running, pressing kbd:[Ctrl+t] displays the current state of the build.
 Poudriere also builds files in [.filename]#/poudriere/logs/bulk/jailname# that can be used with a web server to display build information.
 
 After completion, the new packages are now available for installation from the poudriere repository.
 
 For more information on using poudriere, see man:poudriere[8] and the main web site, https://github.com/freebsd/poudriere/wiki[].
 
 === Configuring pkg Clients to Use a Poudriere Repository
 
 While it is possible to use both a custom repository along side of the official repository, sometimes it is useful to disable the official repository.
 This is done by creating a configuration file that overrides and disables the official configuration file.
 Create [.filename]#/usr/local/etc/pkg/repos/FreeBSD.conf# that contains the following:
 
 [.programlisting]
 ....
 FreeBSD: {
 	enabled: no
 }
 ....
 
 Usually it is easiest to serve a poudriere repository to the client machines via HTTP.
 Set up a webserver to serve up the package directory, for instance: [.filename]#/usr/local/poudriere/data/packages/11amd64#, where [.filename]#11amd64# is the name of the build.
 
 If the URL to the package repository is: `http://pkg.example.com/11amd64`,
 then the repository configuration file in [.filename]#/usr/local/etc/pkg/repos/custom.conf# would look like:
 
 [.programlisting]
 ....
 custom: {
 	url: "http://pkg.example.com/11amd64",
 	enabled: yes,
 }
 ....
 
 [[ports-nextsteps]]
 == Post-Installation Considerations
 
 Regardless of whether the software was installed from a binary package or port, most third-party applications require some level of configuration after installation.
 The following commands and locations can be used to help determine what was installed with the application.
 
 * Most applications install at least one default configuration file in [.filename]#/usr/local/etc#. In cases where an application has a large number of configuration files, a subdirectory will be created to hold them. Often, sample configuration files are installed which end with a suffix such as [.filename]#.sample#. The configuration files should be reviewed and possibly edited to meet the system's needs. To edit a sample file, first copy it without the [.filename]#.sample# extension.
 * Applications which provide documentation will install it into [.filename]#/usr/local/share/doc# and many applications also install manual pages. This documentation should be consulted before continuing.
 * Some applications run services which must be added to [.filename]#/etc/rc.conf# before starting the application. These applications usually install a startup script in [.filename]#/usr/local/etc/rc.d#. See crossref:config[configtuning-starting-services,Starting Services] for more information.
 +
 [NOTE]
 ====
 By design, applications do not run their startup script upon installation, nor do they run their stop script upon deinstallation or upgrade.
 This decision is left to the individual system administrator.
 ====
 
 * Users of man:csh[1] should run `rehash` to rebuild the known binary list in the shells `PATH`.
 * Use `pkg info` to determine which files, man pages, and binaries were installed with the application.
 
 [[ports-broken]]
 == Dealing with Broken Ports
 
 When a port does not build or install, try the following:
 
 . Search to see if there is a fix pending for the port in the link:https://www.FreeBSD.org/support/[Problem Report database]. If so, implementing the proposed fix may fix the issue.
 . Ask the maintainer of the port for help. Type `make maintainer` in the ports skeleton or read the port's [.filename]#Makefile# to find the maintainer's email address. Remember to include the `$FreeBSD:` line from the port's [.filename]#Makefile# and the output leading up to the error in the email to the maintainer.
 +
 [NOTE]
 ====
 Some ports are not maintained by an individual but instead by a group maintainer represented by a link:{mailing-list-faq}[mailing list].
 Many, but not all, of these addresses look like mailto:freebsd-listname@FreeBSD.org[freebsd-listname@FreeBSD.org].
 Please take this into account when sending an email.
 
 In particular, ports maintained by mailto:ports@FreeBSD.org[ports@FreeBSD.org] are not maintained by a specific individual.
 Instead, any fixes and support come from the general community who subscribe to that mailing list. More volunteers are always needed!
 ====
-+ 
++
 If there is no response to the email, use Bugzilla to submit a bug report using the instructions in link:{problem-reports}[Writing FreeBSD Problem Reports].
 . Fix it! The link:{porters-handbook}[Porter's Handbook] includes detailed information on the ports infrastructure so that you can fix the occasional broken port or even submit your own!
 . Install the package instead of the port using the instructions in <<pkgng-intro>>.
diff --git a/documentation/content/en/books/handbook/ppp-and-slip/_index.adoc b/documentation/content/en/books/handbook/ppp-and-slip/_index.adoc
index 887f9088e0..1362bcab8a 100644
--- a/documentation/content/en/books/handbook/ppp-and-slip/_index.adoc
+++ b/documentation/content/en/books/handbook/ppp-and-slip/_index.adoc
@@ -1,937 +1,937 @@
 ---
 title: Chapter 28. PPP
 part: IV. Network Communication
 prev: books/handbook/serialcomms
 next: books/handbook/mail
 description: FreeBSD supports the Point-to-Point (PPP) protocol which can be used to establish a network or Internet connection using a dial-up modem
 tags: ["PPP", "PPPoE", "PPPoA", "modem"]
 ---
 
 [[ppp-and-slip]]
 = PPP
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 28
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/ppp-and-slip/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/ppp-and-slip/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/ppp-and-slip/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[ppp-and-slip-synopsis]]
 == Synopsis
 
 FreeBSD supports the Point-to-Point (PPP) protocol which can be used to establish a network or Internet connection using a dial-up modem.
 This chapter describes how to configure modem-based communication services in FreeBSD.
 
 After reading this chapter, you will know:
 
 * How to configure, use, and troubleshoot a PPP connection.
 * How to set up PPP over Ethernet (PPPoE).
 * How to set up PPP over ATM (PPPoA).
 
 Before reading this chapter, you should:
 
 * Be familiar with basic network terminology.
 * Understand the basics and purpose of a dial-up connection and PPP.
 
 [[userppp]]
 == Configuring PPP
 
 FreeBSD provides built-in support for managing dial-up PPP connections using man:ppp[8].
 The default FreeBSD kernel provides support for [.filename]#tun# which is used to interact with a modem hardware.
 Configuration is performed by editing at least one configuration file, and configuration files containing examples are provided.
 Finally, `ppp` is used to start and manage connections.
 
 In order to use a PPP connection, the following items are needed:
 
 * A dial-up account with an Internet Service Provider (ISP).
 * A dial-up modem.
 * The dial-up number for the ISP.
 * The login name and password assigned by the ISP.
 * The IP address of one or more DNS servers. Normally, the ISP provides these addresses. If it did not, FreeBSD can be configured to use DNS negotiation.
 
 If any of the required information is missing, contact the ISP.
 
 The following information may be supplied by the ISP, but is not necessary:
 
 * The IP address of the default gateway. If this information is unknown, the ISP will automatically provide the correct value during connection setup. When configuring PPP on FreeBSD, this address is referred to as `HISADDR`.
 * The subnet mask. If the ISP has not provided one, `255.255.255.255` will be used in the man:ppp[8] configuration file.
 *
-+ 
++
 If the ISP has assigned a static IP address and hostname, it should be input into the configuration file. Otherwise, this information will be automatically provided during connection setup.
 
 The rest of this section demonstrates how to configure FreeBSD for common PPP connection scenarios.
 The required configuration file is [.filename]#/etc/ppp/ppp.conf# and additional files and examples are available in [.filename]#/usr/share/examples/ppp/#.
 
 [NOTE]
 ====
 Throughout this section, many of the file examples display line numbers.
 These line numbers have been added to make it easier to follow the discussion and are not meant to be placed in the actual file.
 
 When editing a configuration file, proper indentation is important.
 Lines that end in a `:` start in the first column (beginning of the line) while all other lines should be indented as shown using spaces or tabs.
 ====
 
 [[userppp-staticIP]]
 === Basic Configuration
 
 In order to configure a PPP connection, first edit [.filename]#/etc/ppp/ppp.conf# with the dial-in information for the ISP.
 This file is described as follows:
 
 [.programlisting]
 ....
 1     default:
 2       set log Phase Chat LCP IPCP CCP tun command
 3       ident user-ppp VERSION
 4       set device /dev/cuau0
 5       set speed 115200
 6       set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \
 7                 \"\" AT OK-AT-OK ATE1Q0 OK \\dATDT\\T TIMEOUT 40 CONNECT"
 8       set timeout 180
 9       enable dns
 10
 11    provider:
 12      set phone "(123) 456 7890"
 13      set authname foo
 14      set authkey bar
 15      set timeout 300
 16      set ifaddr x.x.x.x/0 y.y.y.y/0 255.255.255.255 0.0.0.0
 17      add default HISADDR
 ....
 
 Line 1:::
 Identifies the `default` entry.
 Commands in this entry (lines 2 through 9) are executed automatically when `ppp` is run.
 
 Line 2:::
 Enables verbose logging parameters for testing the connection.
 Once the configuration is working satisfactorily, this line should be reduced to:
 +
 [.programlisting]
 ....
 set log phase tun
 ....
 
 Line 3:::
 Displays the version of man:ppp[8] to the PPP software running on the other side of the connection.
 
 Line 4:::
 Identifies the device to which the modem is connected, where [.filename]#COM1# is [.filename]#/dev/cuau0# and [.filename]#COM2# is [.filename]#/dev/cuau1#.
 
 Line 5:::
 Sets the connection speed.
 If `115200` does not work on an older modem, try `38400` instead.
 
 Lines 6 & 7:::
 The dial string written as an expect-send syntax.
 Refer to man:chat[8] for more information.
 +
 Note that this command continues onto the next line for readability.
 Any command in [.filename]#ppp.conf# may do this if the last character on the line is `\`.
 
 Line 8:::
 Sets the idle timeout for the link in seconds.
 
 Line 9:::
 Instructs the peer to confirm the DNS settings.
 If the local network is running its own DNS server, this line should be commented out, by adding a `#` at the beginning of the line, or removed.
 
 Line 10:::
 A blank line for readability. Blank lines are ignored by man:ppp[8].
 
 Line 11:::
 Identifies an entry called `provider`.
 This could be changed to the name of the ISP so that `load _ISP_` can be used to start the connection.
 
 Line 12:::
 Use the phone number for the ISP.
 Multiple phone numbers may be specified using the colon (`:`) or pipe character (`|`) as a separator.
 To rotate through the numbers, use a colon.
 To always attempt to dial the first number first and only use the other numbers if the first number fails, use the pipe character.
 Always enclose the entire set of phone numbers between quotation marks (`"`) to prevent dialing failures.
 
 Lines 13 & 14:::
 Use the user name and password for the ISP.
 
 Line 15:::
 Sets the default idle timeout in seconds for the connection.
 In this example, the connection will be closed automatically after 300 seconds of inactivity.
 To prevent a timeout, set this value to zero.
 
 Line 16:::
 Sets the interface addresses.
 The values used depend upon whether a static IP address has been obtained from the ISP or if it instead negotiates a dynamic IP address during connection.
 +
 If the ISP has allocated a static IP address and default gateway, replace _x.x.x.x_ with the static IP address and replace _y.y.y.y_ with the IP address of the default gateway.
 If the ISP has only provided a static IP address without a gateway address, replace _y.y.y.y_ with `10.0.0.2/0`.
 +
 If the IP address changes whenever a connection is made, change this line to the following value.
 This tells man:ppp[8] to use the IP Configuration Protocol (IPCP) to negotiate a dynamic IP address:
 +
 [.programlisting]
 ....
 set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.255 0.0.0.0
 ....
 
 Line 17:::
 Keep this line as-is as it adds a default route to the gateway.
 The `HISADDR` will automatically be replaced with the gateway address specified on line 16.
 It is important that this line appears after line 16.
 
 Depending upon whether man:ppp[8] is started manually or automatically, a [.filename]#/etc/ppp/ppp.linkup# may also need to be created which contains the following lines.
 This file is required when running `ppp` in `-auto` mode.
 This file is used after the connection has been established.
 At this point, the IP address will have been assigned and it is now possible to add the routing table entries.
 When creating this file, make sure that _provider_ matches the value demonstrated in line 11 of [.filename]#ppp.conf#.
 
 [.programlisting]
 ....
 provider:
       add default HISADDR
 ....
 
 This file is also needed when the default gateway address is "guessed" in a static IP address configuration.
 In this case, remove line 17 from [.filename]#ppp.conf# and create [.filename]#/etc/ppp/ppp.linkup# with the above two lines.
 More examples for this file can be found in [.filename]#/usr/share/examples/ppp/#.
 
 By default, `ppp` must be run as `root`.
 To change this default, add the account of the user who should run `ppp` to the `network` group in [.filename]#/etc/group#.
 
 Then, give the user access to one or more entries in [.filename]#/etc/ppp/ppp.conf# with `allow`.
 For example, to give `fred` and `mary` permission to only the `provider:` entry, add this line to the `provider:` section:
 
 [.programlisting]
 ....
 allow users fred mary
 ....
 
 To give the specified users access to all entries, put that line in the `default` section instead.
 
 === Advanced Configuration
 
 It is possible to configure PPP to supply DNS and NetBIOS nameserver addresses on demand.
 
 To enable these extensions with PPP version 1.x, the following lines might be added to the relevant section of [.filename]#/etc/ppp/ppp.conf#.
 
 [.programlisting]
 ....
 enable msext
 set ns 203.14.100.1 203.14.100.2
 set nbns 203.14.100.5
 ....
 
 And for PPP version 2 and above:
 
 [.programlisting]
 ....
 accept dns
 set dns 203.14.100.1 203.14.100.2
 set nbns 203.14.100.5
 ....
 
 This will tell the clients the primary and secondary name server addresses, and a NetBIOS nameserver host.
 
 In version 2 and above, if the `set dns` line is omitted, PPP will use the values found in [.filename]#/etc/resolv.conf#.
 
 [[userppp-PAPnCHAP]]
 ==== PAP and CHAP Authentication
 
 Some ISPs set their system up so that the authentication part of the connection is done using either of the PAP or CHAP authentication mechanisms.
 If this is the case, the ISP will not give a `login:` prompt at connection, but will start talking PPP immediately.
 
 PAP is less secure than CHAP, but security is not normally an issue here as passwords, although being sent as plain text with PAP, are being transmitted down a serial line only.
 There is not much room for crackers to "eavesdrop".
 
 The following alterations must be made:
 
 [.programlisting]
 ....
 13      set authname MyUserName
 14      set authkey MyPassword
 15      set login
 ....
 
 Line 13:::
 This line specifies the PAP/CHAP user name.Insert the correct value for _MyUserName_.
 
 Line 14:::
 This line specifies the PAP/CHAP password.
 Insert the correct value for _MyPassword_.
 You may want to add an additional line, such as:
 +
 [.programlisting]
 ....
 16      accept PAP
 ....
 +
 or
 +
 [.programlisting]
 ....
 16      accept CHAP
 ....
 +
 to make it obvious that this is the intention, but PAP and CHAP are both accepted by default.
 
 Line 15:::
 The ISP will not normally require a login to the server when using PAP or CHAP.
 Therefore, disable the "set login" string.
 
 [[userppp-nat]]
 ==== Using PPP Network Address Translation Capability
 
 PPP has ability to use internal NAT without kernel diverting capabilities.
 This functionality may be enabled by the following line in [.filename]#/etc/ppp/ppp.conf#:
 
 [.programlisting]
 ....
 nat enable yes
 ....
 
 Alternatively, NAT may be enabled by command-line option `-nat`.
 There is also [.filename]#/etc/rc.conf# knob named `ppp_nat`, which is enabled by default.
 
 When using this feature, it may be useful to include the following [.filename]#/etc/ppp/ppp.conf# options to enable incoming connections forwarding:
 
 [.programlisting]
 ....
 nat port tcp 10.0.0.2:ftp ftp
 nat port tcp 10.0.0.2:http http
 ....
 
 or do not trust the outside at all
 
 [.programlisting]
 ....
 nat deny_incoming yes
 ....
 
 [[userppp-final]]
 === Final System Configuration
 
 While `ppp` is now configured, some edits still need to be made to [.filename]#/etc/rc.conf#.
 
 Working from the top down in this file, make sure the `hostname=` line is set:
 
 [.programlisting]
 ....
 hostname="foo.example.com"
 ....
 
 If the ISP has supplied a static IP address and name, use this name as the host name.
 
 Look for the `network_interfaces` variable.
 To configure the system to dial the ISP on demand, make sure the [.filename]#tun0# device is added to the list, otherwise remove it.
 
 [.programlisting]
 ....
 network_interfaces="lo0 tun0"
 ifconfig_tun0=
 ....
 
 [NOTE]
 ====
 The `ifconfig_tun0` variable should be empty, and a file called [.filename]#/etc/start_if.tun0# should be created.
 This file should contain the line:
 
 [.programlisting]
 ....
 ppp -auto mysystem
 ....
 
 This script is executed at network configuration time, starting the ppp daemon in automatic mode.
 If this machine acts as a gateway, consider including `-alias`. Refer to the manual page for further details.
 ====
 
 Make sure that the router program is set to `NO` with the following line in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 router_enable="NO"
 ....
 
 It is important that the `routed` daemon is not started, as `routed` tends to delete the default routing table entries created by `ppp`.
 
 It is probably a good idea to ensure that the `sendmail_flags` line does not include the `-q` option, otherwise `sendmail` will attempt to do a network lookup every now and then, possibly causing your machine to dial out.
 You may try:
 
 [.programlisting]
 ....
 sendmail_flags="-bd"
 ....
 
 The downside is that `sendmail` is forced to re-examine the mail queue whenever the ppp link.
 To automate this, include `!bg` in [.filename]#ppp.linkup#:
 
 [.programlisting]
 ....
 1     provider:
 2       delete ALL
 3       add 0 0 HISADDR
 4       !bg sendmail -bd -q30m
 ....
 
 An alternative is to set up a "dfilter" to block SMTP traffic.
 Refer to the sample files for further details.
 
 === Using `ppp`
 
 All that is left is to reboot the machine.
 After rebooting, either type:
 
 [source,shell]
 ....
 # ppp
 ....
 
 and then `dial provider` to start the PPP session, or, to configure `ppp` to establish sessions automatically when there is outbound traffic and [.filename]#start_if.tun0# does not exist, type:
 
 [source,shell]
 ....
 # ppp -auto provider
 ....
 
 It is possible to talk to the `ppp` program while it is running in the background, but only if a suitable diagnostic port has been set up.
 To do this, add the following line to the configuration:
 
 [.programlisting]
 ....
 set server /var/run/ppp-tun%d DiagnosticPassword 0177
 ....
 
 This will tell PPP to listen to the specified UNIX(R) domain socket, asking clients for the specified password before allowing access.
 The `%d` in the name is replaced with the [.filename]#tun# device number that is in use.
 
 Once a socket has been set up, the man:pppctl[8] program may be used in scripts that wish to manipulate the running program.
 
 [[userppp-mgetty]]
 === Configuring Dial-in Services
 
 crossref:serialcomms[dialup,“Dial-in Service”] provides a good description on enabling dial-up services using man:getty[8].
 
 An alternative to `getty` is package:comms/mgetty+sendfax[] port), a smarter version of `getty` designed with dial-up lines in mind.
 
 The advantages of using `mgetty` is that it actively _talks_ to modems, meaning if port is turned off in [.filename]#/etc/ttys# then the modem will not answer the phone.
 
 Later versions of `mgetty` (from 0.99beta onwards) also support the automatic detection of PPP streams, allowing clients scriptless access to the server.
 
 Refer to http://mgetty.greenie.net/doc/mgetty_toc.html[http://mgetty.greenie.net/doc/mgetty_toc.html] for more information on `mgetty`.
 
 By default the package:comms/mgetty+sendfax[] port comes with the `AUTO_PPP` option enabled allowing `mgetty` to detect the LCP phase of PPP connections and automatically spawn off a ppp shell.
 However, since the default login/password sequence does not occur it is necessary to authenticate users using either PAP or CHAP.
 
 This section assumes the user has successfully compiled, and installed the package:comms/mgetty+sendfax[] port on his system.
 
 Ensure that [.filename]#/usr/local/etc/mgetty+sendfax/login.config# has the following:
 
 [.programlisting]
 ....
 /AutoPPP/ -     - /etc/ppp/ppp-pap-dialup
 ....
 
 This tells `mgetty` to run [.filename]#ppp-pap-dialup# for detected PPP connections.
 
 Create an executable file called [.filename]#/etc/ppp/ppp-pap-dialup# containing the following:
 
 [.programlisting]
 ....
 #!/bin/sh
 exec /usr/sbin/ppp -direct pap$IDENT
 ....
 
 For each dial-up line enabled in [.filename]#/etc/ttys#, create a corresponding entry in [.filename]#/etc/ppp/ppp.conf#.
 This will happily co-exist with the definitions we created above.
 
 [.programlisting]
 ....
 pap:
   enable pap
   set ifaddr 203.14.100.1 203.14.100.20-203.14.100.40
   enable proxy
 ....
 
 Each user logging in with this method will need to have a username/password in [.filename]#/etc/ppp/ppp.secret#, or alternatively add the following option to authenticate users via PAP from [.filename]#/etc/passwd#.
 
 [.programlisting]
 ....
 enable passwdauth
 ....
 
 To assign some users a static IP number, specify the number as the third argument in [.filename]#/etc/ppp/ppp.secret#.
 See [.filename]#/usr/share/examples/ppp/ppp.secret.sample# for examples.
 
 [[ppp-troubleshoot]]
 == Troubleshooting PPP Connections
 
 This section covers a few issues which may arise when using PPP over a modem connection.
 Some ISPs present the `ssword` prompt while others present `password`.
 If the `ppp` script is not written accordingly, the login attempt will fail.
 The most common way to debug `ppp` connections is by connecting manually as described in this section.
 
 === Check the Device Nodes
 
 When using a custom kernel, make sure to include the following line in the kernel configuration file:
 
 [.programlisting]
 ....
 device   uart
 ....
 
 The [.filename]#uart# device is already included in the `GENERIC` kernel, so no additional steps are necessary in this case.
 Just check the `dmesg` output for the modem device with:
 
 [source,shell]
 ....
 # dmesg | grep uart
 ....
 
 This should display some pertinent output about the [.filename]#uart# devices.
 These are the COM ports we need.
 If the modem acts like a standard serial port, it should be listed on [.filename]#uart1#, or [.filename]#COM2#.
 If so, a kernel rebuild is not required.
 When matching up, if the modem is on [.filename]#uart1#, the modem device would be [.filename]#/dev/cuau1#.
 
 === Connecting Manually
 
 Connecting to the Internet by manually controlling `ppp` is quick, easy, and a great way to debug a connection or just get information on how the ISP treats `ppp` client connections.
 Lets start PPP from the command line.
 Note that in all of our examples we will use _example_ as the hostname of the machine running PPP.
 To start `ppp`:
 
 [source,shell]
 ....
 # ppp
 ....
 
 [source,shell]
 ....
 ppp ON example> set device /dev/cuau1
 ....
 
 This second command sets the modem device to [.filename]#cuau1#.
 
 [source,shell]
 ....
 ppp ON example> set speed 115200
 ....
 
 This sets the connection speed to 115,200 kbps.
 
 [source,shell]
 ....
 ppp ON example> enable dns
 ....
 
 This tells `ppp` to configure the resolver and add the nameserver lines to [.filename]#/etc/resolv.conf#.
 If `ppp` cannot determine the hostname, it can manually be set later.
 
 [source,shell]
 ....
 ppp ON example> term
 ....
 
 This switches to "terminal" mode in order to manually control the modem.
 
 [.programlisting]
 ....
 deflink: Entering terminal mode on /dev/cuau1
 type '~h' for help
 ....
 
 [source,shell]
 ....
 at
 OK
 atdt123456789
 ....
 
 Use `at` to initialize the modem, then use `atdt` and the number for the ISP to begin the dial in process.
 
 [source,shell]
 ....
 CONNECT
 ....
 
 Confirmation of the connection, if we are going to have any connection problems, unrelated to hardware, here is where we will attempt to resolve them.
 
 [source,shell]
 ....
 ISP Login:myusername
 ....
 
 At this prompt, return the prompt with the username that was provided by the ISP.
 
 [source,shell]
 ....
 ISP Pass:mypassword
 ....
 
 At this prompt, reply with the password that was provided by the ISP.
 Just like logging into FreeBSD, the password will not echo.
 
 [source,shell]
 ....
 Shell or PPP:ppp
 ....
 
 Depending on the ISP, this prompt might not appear.
 If it does, it is asking whether to use a shell on the provider or to start `ppp`.
 In this example, `ppp` was selected in order to establish an Internet connection.
 
 [source,shell]
 ....
 Ppp ON example>
 ....
 
 Notice that in this example the first `p` has been capitalized.
 This shows that we have successfully connected to the ISP.
 
 [source,shell]
 ....
 Ppp ON example>
 ....
 
 We have successfully authenticated with our ISP and are waiting for the assigned IP address.
 
 [source,shell]
 ....
 PPP ON example>
 ....
 
 We have made an agreement on an IP address and successfully completed our connection.
 
 [source,shell]
 ....
 PPP ON example>add default HISADDR
 ....
 
 Here we add our default route, we need to do this before we can talk to the outside world as currently the only established connection is with the peer.
 If this fails due to existing routes, put a bang character `!` in front of the `add`.
 Alternatively, set this before making the actual connection and it will negotiate a new route accordingly.
 
 If everything went good we should now have an active connection to the Internet, which could be thrown into the background using kbd:[CTRL+z].
 If `PPP` returns to `ppp` the connection has been lost.
 This is good to know because it shows the connection status.
 Capital P's represent a connection to the ISP and lowercase p's show that the connection has been lost.
 
 === Debugging
 
 If a connection cannot be established, turn hardware flow CTS/RTS to off using `set ctsrts off`.
 This is mainly the case when connected to some PPP-capable terminal servers, where PPP hangs when it tries to write data to the communication link, and waits for a Clear To Send (CTS) signal which may never come.
 When using this option, include `set accmap` as it may be required to defeat hardware dependent on passing certain characters from end to end, most of the time XON/XOFF.
 Refer to man:ppp[8] for more information on this option and how it is used.
 
 An older modem may need `set parity even`.
 Parity is set at none be default, but is used for error checking with a large increase in traffic, on older modems.
 
 PPP may not return to the command mode, which is usually a negotiation error where the ISP is waiting for negotiating to begin.
 At this point, using `~p` will force ppp to start sending the configuration information.
 
 If a login prompt never appears, PAP or CHAP authentication is most likely required.
 To use PAP or CHAP, add the following options to PPP before going into terminal mode:
 
 [source,shell]
 ....
 ppp ON example> set authname myusername
 ....
 
 Where _myusername_ should be replaced with the username that was assigned by the ISP.
 
 [source,shell]
 ....
 ppp ON example> set authkey mypassword
 ....
 
 Where _mypassword_ should be replaced with the password that was assigned by the ISP.
 
 If a connection is established, but cannot seem to find any domain name, try to man:ping[8] an IP address.
 If there is 100 percent (100%) packet loss, it is likely that a default route was not assigned.
 Double check that `add default HISADDR` was set during the connection.
 If a connection can be made to a remote IP address, it is possible that a resolver address has not been added to [.filename]#/etc/resolv.conf#.
 This file should look like:
 
 [.programlisting]
 ....
 domain example.com
 nameserver x.x.x.x
 nameserver y.y.y.y
 ....
 
 Where _x.x.x.x_ and _y.y.y.y_ should be replaced with the IP address of the ISP's DNS servers.
 
 To configure man:syslog[3] to provide logging for the PPP connection, make sure this line exists in [.filename]#/etc/syslog.conf#:
 
 [.programlisting]
 ....
 !ppp
 *.*     /var/log/ppp.log
 ....
 
 [[pppoe]]
 == Using PPP over Ethernet (PPPoE)
 
 This section describes how to set up PPP over Ethernet (PPPoE).
 
 Here is an example of a working [.filename]#ppp.conf#:
 
 [.programlisting]
 ....
 default:
   set log Phase tun command # you can add more detailed logging if you wish
   set ifaddr 10.0.0.1/0 10.0.0.2/0
 
 name_of_service_provider:
   set device PPPoE:xl1 # replace xl1 with your Ethernet device
   set authname YOURLOGINNAME
   set authkey YOURPASSWORD
   set dial
   set login
   add default HISADDR
 ....
 
 As `root`, run:
 
 [source,shell]
 ....
 # ppp -ddial name_of_service_provider
 ....
 
 Add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 ppp_enable="YES"
 ppp_mode="ddial"
 ppp_nat="YES"	# if you want to enable nat for your local network, otherwise NO
 ppp_profile="name_of_service_provider"
 ....
 
 === Using a PPPoE Service Tag
 
 Sometimes it will be necessary to use a service tag to establish the connection.
 Service tags are used to distinguish between different PPPoE servers attached to a given network.
 
 Any required service tag information should be in the documentation provided by the ISP.
 
 As a last resort, one could try installing the package:net/rr-pppoe[] package or port.
 Bear in mind however, this may de-program your modem and render it useless, so think twice before doing it.
 Simply install the program shipped with the modem.
 Then, access the menu:System[] menu from the program.
 The name of the profile should be listed there.
 It is usually _ISP_.
 
 The profile name (service tag) will be used in the PPPoE configuration entry in [.filename]#ppp.conf# as the provider part for `set device`.
 Refer to man:ppp[8] for full details. It should look like this:
 
 [.programlisting]
 ....
 set device PPPoE:xl1:ISP
 ....
 
 Do not forget to change _xl1_ to the proper device for the Ethernet card.
 
 Do not forget to change _ISP_ to the profile.
 
 For additional information, refer to http://renaud.waldura.com/doc/freebsd/pppoe/[Cheaper Broadband with FreeBSD on DSL] by Renaud Waldura.
 
 [[ppp-3com]]
 === PPPoE with a 3Com(R) HomeConnect(TM) ADSL Modem Dual Link
 
 This modem does not follow the PPPoE specification defined in http://www.faqs.org/rfcs/rfc2516.html[RFC 2516].
 
 In order to make FreeBSD capable of communicating with this device, a sysctl must be set.
 This can be done automatically at boot time by updating [.filename]#/etc/sysctl.conf#:
 
 [.programlisting]
 ....
 net.graph.nonstandard_pppoe=1
 ....
 
 or can be done immediately with the command:
 
 [source,shell]
 ....
 # sysctl net.graph.nonstandard_pppoe=1
 ....
 
 Unfortunately, because this is a system-wide setting, it is not possible to talk to a normal PPPoE client or server and a 3Com(R) HomeConnect(TM) ADSL Modem at the same time.
 
 [[pppoa]]
 == Using PPP over ATM (PPPoA)
 
 The following describes how to set up PPP over ATM (PPPoA).
 PPPoA is a popular choice among European DSL providers.
 
 === Using mpd
 
 The mpd application can be used to connect to a variety of services, in particular PPTP services.
 It can be installed using the package:net/mpd5[] package or port.
 Many ADSL modems require that a PPTP tunnel is created between the modem and computer.
 
 Once installed, configure mpd to suit the provider's settings.
 The port places a set of sample configuration files which are well documented in [.filename]#/usr/local/etc/mpd/#.
 A complete guide to configure mpd is available in HTML format in [.filename]#/usr/ports/shared/doc/mpd/#.
 Here is a sample configuration for connecting to an ADSL service with mpd.
 The configuration is spread over two files, first the [.filename]#mpd.conf#:
 
 [NOTE]
 ====
 This example [.filename]#mpd.conf# only works with mpd 4.x.
 ====
 
 [.programlisting]
 ....
 default:
     load adsl
 
 adsl:
     new -i ng0 adsl adsl
     set bundle authname username <.>
     set bundle password password <.>
     set bundle disable multilink
 
     set link no pap acfcomp protocomp
     set link disable chap
     set link accept chap
     set link keep-alive 30 10
 
     set ipcp no vjcomp
     set ipcp ranges 0.0.0.0/0 0.0.0.0/0
 
     set iface route default
     set iface disable on-demand
     set iface enable proxy-arp
     set iface idle 0
 
     open
 ....
 
 <.> The username used to authenticate with your ISP.
 <.> The password used to authenticate with your ISP.
 
 Information about the link, or links, to establish is found in [.filename]#mpd.links#.
 An example [.filename]#mpd.links# to accompany the above example is given beneath:
 
 [.programlisting]
 ....
 adsl:
     set link type pptp
     set pptp mode active
     set pptp enable originate outcall
     set pptp self 10.0.0.1 <.>
     set pptp peer 10.0.0.138 <.>
 ....
 
 <.> The IP address of FreeBSD computer running mpd.
 <.> The IP address of the ADSL modem. The Alcatel SpeedTouch(TM) Home defaults to `10.0.0.138`.
 
 It is possible to initialize the connection easily by issuing the following command as `root`:
 
 [source,shell]
 ....
 # mpd -b adsl
 ....
 
 To view the status of the connection:
 
 [source,shell]
 ....
 % ifconfig ng0
 ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> mtu 1500
      inet 216.136.204.117 --> 204.152.186.171 netmask 0xffffffff
 ....
 
 Using mpd is the recommended way to connect to an ADSL service with FreeBSD.
 
 === Using pptpclient
 
 It is also possible to use FreeBSD to connect to other PPPoA services using package:net/pptpclient[].
 
 To use package:net/pptpclient[] to connect to a DSL service, install the port or package, then edit [.filename]#/etc/ppp/ppp.conf#.
 An example section of [.filename]#ppp.conf# is given below.
 For further information on [.filename]#ppp.conf# options consult man:ppp[8].
 
 [.programlisting]
 ....
 adsl:
  set log phase chat lcp ipcp ccp tun command
  set timeout 0
  enable dns
  set authname username <.>
  set authkey password <.>
  set ifaddr 0 0
  add default HISADDR
 ....
 
 <.> The username for the DSL provider.
 <.> The password for your account.
 
 [WARNING]
 ====
 
 Since the account's password is added to [.filename]#ppp.conf# in plain text form, make sure nobody can read the contents of this file:
 
 [source,shell]
 ....
 # chown root:wheel /etc/ppp/ppp.conf
 # chmod 600 /etc/ppp/ppp.conf
 ....
 
 ====
 
 This will open a tunnel for a PPP session to the DSL router.
 Ethernet DSL modems have a preconfigured LAN IP address to connect to.
 In the case of the Alcatel SpeedTouch(TM) Home, this address is `10.0.0.138`.
 The router's documentation should list the address the device uses.
 To open the tunnel and start a PPP session:
 
 [source,shell]
 ....
 # pptp address adsl
 ....
 
 [TIP]
 ====
 
 If an ampersand ("&") is added to the end of this command, pptp will return the prompt.
 ====
 
 A [.filename]#tun# virtual tunnel device will be created for interaction between the pptp and ppp processes.
 Once the prompt is returned, or the pptp process has confirmed a connection, examine the tunnel:
 
 [source,shell]
 ....
 % ifconfig tun0
 tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
         inet 216.136.204.21 --> 204.152.186.171 netmask 0xffffff00
 	Opened by PID 918
 ....
 
 If the connection fails, check the configuration of the router, which is usually accessible using a web browser.
 Also, examine the output of `pptp` and the contents of the log file, [.filename]#/var/log/ppp.log# for clues.
diff --git a/documentation/content/en/books/handbook/printing/_index.adoc b/documentation/content/en/books/handbook/printing/_index.adoc
index a4465b38c0..e6d06d640f 100644
--- a/documentation/content/en/books/handbook/printing/_index.adoc
+++ b/documentation/content/en/books/handbook/printing/_index.adoc
@@ -1,900 +1,900 @@
 ---
 title: Chapter 9. Printing
 part: Part II. Common Tasks
 prev: books/handbook/kernelconfig
 next: books/handbook/linuxemu
 description: This chapter covers the printing system in FreeBSD
 tags: ["printing", "CUPS", "LPD", "PostScript", "PDLs", "HPLIP", "LPRng"]
 ---
 
 [[printing]]
 = Printing
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 9
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/printing/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/printing/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/printing/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 Putting information on paper is a vital function, despite many attempts to eliminate it.
 Printing has two basic components.
 The data must be delivered to the printer, and must be in a form that the printer can understand.
 
 [[printing-quick-start]]
 == Quick Start
 
 Basic printing can be set up quickly.
 The printer must be capable of printing plain `ASCII` text.
 For printing to other types of files, see <<printing-lpd-filters>>.
 
 [.procedure]
 ****
 . Create a directory to store files while they are being printed:
 +
 [source,shell]
 ....
 # mkdir -p /var/spool/lpd/lp
 # chown daemon:daemon /var/spool/lpd/lp
 # chmod 770 /var/spool/lpd/lp
 ....
 +
 . As `root`, create [.filename]#/etc/printcap# with these contents:
 +
 [.programlisting]
 ....
 lp:\
 	:lp=/dev/unlpt0:\  <.>
 	:sh:\
 	:mx#0:\
 	:sd=/var/spool/lpd/lp:\
 	:lf=/var/log/lpd-errs:
 ....
 +
 <.> This line is for a printer connected to a `USB` port.
 +
 For a printer connected to a parallel or "printer" port, use:
 +
 [.programlisting]
 ....
 :lp=/dev/lpt0:\
 ....
 +
 For a printer connected directly to a network, use:
 +
 [.programlisting]
 ....
 :lp=:rm=network-printer-name:rp=raw:\
 ....
 +
 Replace _network-printer-name_ with the `DNS` host name of the network printer.
 +
 . Enable LPD by editing [.filename]#/etc/rc.conf#, adding this line:
 +
 [.programlisting]
 ....
 lpd_enable="YES"
 ....
-+ 
++
 Start the service:
 +
 [source,shell]
 ....
 # service lpd start
 Starting lpd.
 ....
 +
 . Print a test:
 +
 [source,shell]
 ....
 # printf "1. This printer can print.\n2. This is the second line.\n" | lpr
 ....
 +
 [TIP]
 ====
 If both lines do not start at the left border, but "stairstep" instead, see <<printing-lpd-filters-stairstep>>.
 ====
-+ 
++
 Text files can now be printed with `lpr`.
 Give the filename on the command line, or pipe output directly into `lpr`.
 +
 [source,shell]
 ....
 % lpr textfile.txt
 % ls -lh | lpr
 ....
 ****
 
 [[printing-connections]]
 == Printer Connections
 
 Printers are connected to computer systems in a variety of ways.
 Small desktop printers are usually connected directly to a computer's `USB` port.
 Older printers are connected to a parallel or "printer" port.
 Some printers are directly connected to a network, making it easy for multiple computers to share them.
 A few printers use a rare serial port connection.
 
 FreeBSD can communicate with all of these types of printers.
 
 [[printing-connections-usb]]
 `USB`::
 `USB` printers can be connected to any available `USB` port on the computer.
 +
 When FreeBSD detects a `USB` printer, two device entries are created: [.filename]#/dev/ulpt0# and [.filename]#/dev/unlpt0#.
 Data sent to either device will be relayed to the printer.
 After each print job, [.filename]#ulpt0# resets the `USB` port.
 Resetting the port can cause problems with some printers, so the [.filename]#unlpt0# device is usually used instead.
 [.filename]#unlpt0# does not reset the USB port at all.
 
 [[printing-connections-parallel]]
 Parallel (`IEEE`-1284)::
 The parallel port device is [.filename]#/dev/lpt0#.
 This device appears whether a printer is attached or not, it is not autodetected.
 +
 Vendors have largely moved away from these "legacy" ports, and many computers no longer have them.
 Adapters can be used to connect a parallel printer to a `USB` port.
 With such an adapter, the printer can be treated as if it were actually a `USB` printer.
 Devices called _print servers_ can also be used to connect parallel printers directly to a network.
 
 [[printing-connections-serial]]
 Serial (RS-232)::
 Serial ports are another legacy port, rarely used for printers except in certain niche applications.
 Cables, connectors, and required wiring vary widely.
 +
 For serial ports built into a motherboard, the serial device name is [.filename]#/dev/cuau0# or [.filename]#/dev/cuau1#.
 Serial `USB` adapters can also be used, and these will appear as [.filename]#/dev/cuaU0#.
 +
 Several communication parameters must be known to communicate with a serial printer.
 The most important are _baud rate_ or `BPS` (Bits Per Second) and _parity_.
 Values vary, but typical serial printers use a baud rate of 9600 and no parity.
 
 [[printing-connections-network]]
 Network::
 Network printers are connected directly to the local computer network.
 +
 The `DNS` hostname of the printer must be known.
 If the printer is assigned a dynamic address by `DHCP`, `DNS` should be dynamically updated so that the host name always has the correct `IP` address. 
 Network printers are often given static `IP` addresses to avoid this problem.
 +
 Most network printers understand print jobs sent with the LPD protocol.
 A print queue name can also be specified.
 Some printers process data differently depending on which queue is used.
 For example, a `raw` queue prints the data unchanged, while the `text` queue adds carriage returns to plain text.
 +
 Many network printers can also print data sent directly to port 9100.
 
 [[printing-connections-summary]]
 === Summary
 
 Wired network connections are usually the easiest to set up and give the fastest printing.
 For direct connection to the computer, `USB` is preferred for speed and simplicity.
 Parallel connections work but have limitations on cable length and speed.
 Serial connections are more difficult to configure.
 Cable wiring differs between models, and communication parameters like baud rate and parity bits must add to the complexity.
 Fortunately, serial printers are rare.
 
 [[printing-pdls]]
 == Common Page Description Languages
 
 Data sent to a printer must be in a language that the printer can understand.
 These languages are called Page Description Languages, or PDLs.
 
 [[print-pdls-ascii]]
 `ASCII`::
 Plain `ASCII` text is the simplest way to send data to a printer.
 Characters correspond one to one with what will be printed: an `A` in the data prints an `A` on the page.
 Very little formatting is available.
 There is no way to select a font or proportional spacing.
 The forced simplicity of plain `ASCII` means that text can be printed straight from the computer with little or no encoding or translation.
 The printed output corresponds directly with what was sent.
 +
 Some inexpensive printers cannot print plain `ASCII` text.
 This makes them more difficult to set up, but it is usually still possible.
 
 [[print-pdls-postscript]]
 PostScript(R)::
 PostScript(R) is almost the opposite of `ASCII`.
 Rather than simple text, a PostScript(R) program is a set of instructions that draw the final document.
 Different fonts and graphics can be used.
 However, this power comes at a price.
 The program that draws the page must be written.
 Usually this program is generated by application software, so the process is invisible to the user.
 +
 Inexpensive printers sometimes leave out PostScript(R) compatibility as a cost-saving measure.
 
 [[print-pdls-pcl]]
 `PCL` (Printer Command Language)::
 `PCL` is an extension of `ASCII`, adding escape sequences for formatting, font selection, and printing graphics.
 Many printers provide `PCL5` support.
 Some support the newer `PCL6` or `PCLXL`.
 These later versions are supersets of `PCL5` and can provide faster printing.
 
 [[print-pdls-host-based]]
 Host-Based::
 Manufacturers can reduce the cost of a printer by giving it a simple processor and very little memory.
 These printers are not capable of printing plain text.
 Instead, bitmaps of text and graphics are drawn by a driver on the host computer and then sent to the printer.
 These are called _host-based_ printers.
 +
 Communication between the driver and a host-based printer is often through proprietary or undocumented protocols, making them functional only on the most common operating systems.
 
 [[print-pdls-table]]
 === Converting PostScript(R) to Other PDLs
 
 Many applications from the Ports Collection and FreeBSD utilities produce PostScript(R) output.
 This table shows the utilities available to convert that into other common PDLs:
 
 [[print-pdls-ps-to-other-tbl]]
 .Output PDLs
 [cols="1,1,1", frame="none", options="header"]
 |===
 <| Output PDL
 <| Generated By
 <| Notes
 
 |`PCL` or `PCL5`
 |package:print/ghostscript9-base[]
 |`-sDEVICE=ljet4` for monochrome, `-sDEVICE=cljet5` for color
 
 |`PCLXL` or `PCL6`
 |package:print/ghostscript9-base[]
 |`-sDEVICE=pxlmono` for monochrome, `-sDEVICE=pxlcolor` for color
 
 |`ESC/P2`
 |package:print/ghostscript9-base[]
 |`-sDEVICE=uniprint`
 
 |`XQX`
 |package:print/foo2zjs[]
 |
 |===
 
 [[print-pdls-summary]]
 === Summary
 
 For the easiest printing, choose a printer that supports PostScript(R).
 Printers that support `PCL` are the next preferred.
 With package:print/ghostscript9-base[], these printers can be used as if they understood PostScript(R) natively.
 Printers that support PostScript(R) or `PCL` directly almost always support direct printing of plain `ASCII` text files also.
 
 Line-based printers like typical inkjets usually do not support PostScript(R) or `PCL`.
 They often can print plain `ASCII` text files.
 package:print/ghostscript9-base[] supports the PDLs used by some of these printers.
 However, printing an entire graphic-based page on these printers is often very slow due to the large amount of data to be transferred and printed.
 
 Host-based printers are often more difficult to set up.
 Some cannot be used at all because of proprietary PDLs.
 Avoid these printers when possible.
 
 Descriptions of many PDLs can be found at http://www.undocprint.org/formats/page_description_languages[].
 The particular `PDL` used by various models of printers can be found at http://www.openprinting.org/printers[].
 
 [[printing-direct]]
 == Direct Printing
 
 For occasional printing, files can be sent directly to a printer device without any setup.
 For example, a file called [.filename]#sample.txt# can be sent to a `USB` printer:
 
 [source,shell]
 ....
 # cp sample.txt /dev/unlpt0
 ....
 
 Direct printing to network printers depends on the abilities of the printer, but most accept print jobs on port 9100, and man:nc[1] can be used with them. To print the same file to a printer with the `DNS` hostname of _netlaser_:
 
 [source,shell]
 ....
 # nc netlaser 9100 < sample.txt
 ....
 
 [[printing-lpd]]
 == LPD (Line Printer Daemon)
 
 Printing a file in the background is called _spooling_.
 A spooler allows the user to continue with other programs on the computer without waiting for the printer to slowly complete the print job.
 
 FreeBSD includes a spooler called man:lpd[8].
 Print jobs are submitted with man:lpr[1].
 
 [[printing-lpd-setup]]
 === Initial Setup
 
 A directory for storing print jobs is created, ownership is set, and the permissions are set to prevent other users from viewing the contents of those files:
 
 [source,shell]
 ....
 # mkdir -p /var/spool/lpd/lp
 # chown daemon:daemon /var/spool/lpd/lp
 # chmod 770 /var/spool/lpd/lp
 ....
 
 Printers are defined in [.filename]#/etc/printcap#.
 An entry for each printer includes details like a name, the port where it is attached, and various other settings.
 Create [.filename]#/etc/printcap# with these contents:
 
 [.programlisting]
 ....
 lp:\				<.>
 	:lp=/dev/unlpt0:\	<.>
 	:sh:\			<.>
 	:mx#0:\			<.>
 	:sd=/var/spool/lpd/lp:\	<.>
 	:lf=/var/log/lpd-errs:	<.>
 ....
 
 <.> The name of this printer. man:lpr[1] sends print jobs to the `lp` printer unless another printer is specified with `-P`, so the default printer should be named `lp`.
 
 <.> The device where the printer is connected. Replace this line with the appropriate one for the connection type shown here.
 
 <.> Suppress the printing of a header page at the start of a print job.
 
 <.> Do not limit the maximum size of a print job.
 
 <.> The path to the spooling directory for this printer. Each printer uses its own spooling directory.
 
 <.> The log file where errors on this printer will be reported.
 
 After creating [.filename]#/etc/printcap#, use man:chkprintcap[8] to test it for errors:
 
 [source,shell]
 ....
 # chkprintcap
 ....
 
 Fix any reported problems before continuing.
 
 Enable man:lpd[8] in [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 lpd_enable="YES"
 ....
 
 Start the service:
 
 [source,shell]
 ....
 # service lpd start
 ....
 
 [[printing-lpd-lpr]]
 === Printing with man:lpr[1]
 
 Documents are sent to the printer with `lpr`.
 A file to be printed can be named on the command line or piped into `lpr`.
 These two commands are equivalent, sending the contents of [.filename]#doc.txt# to the default printer:
 
 [source,shell]
 ....
 % lpr doc.txt
 % cat doc.txt | lpr
 ....
 
 Printers can be selected with `-P`.
 To print to a printer called _laser_:
 
 [source,shell]
 ....
 % lpr -Plaser doc.txt
 ....
 
 [[printing-lpd-filters]]
 === Filters
 
 The examples shown so far have sent the contents of a text file directly to the printer.
 As long as the printer understands the content of those files, output will be printed correctly.
 
 Some printers are not capable of printing plain text, and the input file might not even be plain text.
 
 _Filters_ allow files to be translated or processed.
 The typical use is to translate one type of input, like plain text, into a form that the printer can understand, like PostScript(R) or `PCL`.
 Filters can also be used to provide additional features, like adding page numbers or highlighting source code to make it easier to read.
 
 The filters discussed here are _input filters_ or _text filters_.
 These filters convert the incoming file into different forms.
 Use man:su[1] to become `root` before creating the files.
 
 Filters are specified in [.filename]#/etc/printcap# with the `if=` identifier.
 To use [.filename]#/usr/local/libexec/lf2crlf# as a filter, modify [.filename]#/etc/printcap# like this:
 
 [.programlisting]
 ....
 lp:\
 	:lp=/dev/unlpt0:\
 	:sh:\
 	:mx#0:\
 	:sd=/var/spool/lpd/lp:\
 	:if=/usr/local/libexec/lf2crlf:\   <.>
 	:lf=/var/log/lpd-errs:
 ....
 
 <.> `if=` identifies the _input filter_ that will be used on incoming text.
 
 [TIP]
 ====
 The backslash _line continuation_ characters at the end of the lines in [.filename]#printcap# entries reveal that an entry for a printer is really just one long line with entries delimited by colon characters.
 An earlier example can be rewritten as a single less-readable line:
 
 [.programlisting]
 ....
 lp:lp=/dev/unlpt0:sh:mx#0:sd=/var/spool/lpd/lp:if=/usr/local/libexec/lf2crlf:lf=/var/log/lpd-errs:
 ....
 
 ====
 
 [[printing-lpd-filters-stairstep]]
 ==== Preventing Stairstepping on Plain Text Printers
 
 Typical FreeBSD text files contain only a single line feed character at the end of each line.
 These lines will "stairstep" on a standard printer:
 
 [.programlisting]
 ....
 A printed file looks
                     like the steps of a staircase
                                                  scattered by the wind
 ....
 
 A filter can convert the newline characters into carriage returns and newlines.
 The carriage returns make the printer return to the left after each line.
 Create [.filename]#/usr/local/libexec/lf2crlf# with these contents:
 
 [.programlisting]
 ....
 #!/bin/sh
 CR=$'\r'
 /usr/bin/sed -e "s/$/${CR}/g"
 ....
 
 Set the permissions and make it executable:
 
 [source,shell]
 ....
 # chmod 555 /usr/local/libexec/lf2crlf
 ....
 
 Modify [.filename]#/etc/printcap# to use the new filter:
 
 [.programlisting]
 ....
 :if=/usr/local/libexec/lf2crlf:\
 ....
 
 Test the filter by printing the same plain text file.
 The carriage returns will cause each line to start at the left side of the page.
 
 [[printing-lpd-filters-enscript]]
 ==== Fancy Plain Text on PostScript(R) Printers with package:print/enscript[]
 
 GNUEnscript converts plain text files into nicely-formatted PostScript(R) for printing on PostScript(R) printers.
 It adds page numbers, wraps long lines, and provides numerous other features to make printed text files easier to read.
 Depending on the local paper size, install either package:print/enscript-letter[] or package:print/enscript-a4[] from the Ports Collection.
 
 Create [.filename]#/usr/local/libexec/enscript# with these contents:
 
 [.programlisting]
 ....
 #!/bin/sh
 /usr/local/bin/enscript -o -
 ....
 
 Set the permissions and make it executable:
 
 [source,shell]
 ....
 # chmod 555 /usr/local/libexec/enscript
 ....
 
 Modify [.filename]#/etc/printcap# to use the new filter:
 
 [.programlisting]
 ....
 :if=/usr/local/libexec/enscript:\
 ....
 
 Test the filter by printing a plain text file.
 
 [[printing-lpd-filters-ps2pcl]]
 ==== Printing PostScript(R) to `PCL` Printers
 
 Many programs produce PostScript(R) documents.
 However, inexpensive printers often only understand plain text or `PCL`.
 This filter converts PostScript(R) files to `PCL` before sending them to the printer.
 
 Install the Ghostscript PostScript(R) interpreter, package:print/ghostscript9-base[], from the Ports Collection.
 
 Create [.filename]#/usr/local/libexec/ps2pcl# with these contents:
 
 [.programlisting]
 ....
 #!/bin/sh
 /usr/local/bin/gs -dSAFER -dNOPAUSE -dBATCH -q -sDEVICE=ljet4 -sOutputFile=- -
 ....
 
 Set the permissions and make it executable:
 
 [source,shell]
 ....
 # chmod 555 /usr/local/libexec/ps2pcl
 ....
 
 PostScript(R) input sent to this script will be rendered and converted to `PCL` before being sent on to the printer.
 
 Modify [.filename]#/etc/printcap# to use this new input filter:
 
 [.programlisting]
 ....
 :if=/usr/local/libexec/ps2pcl:\
 ....
 
 Test the filter by sending a small PostScript(R) program to it:
 
 [source,shell]
 ....
 % printf "%%\!PS \n /Helvetica findfont 18 scalefont setfont \
 72 432 moveto (PostScript printing successful.) show showpage \004" | lpr
 ....
 
 [[printing-lpd-filters-smart]]
 ==== Smart Filters
 
 A filter that detects the type of input and automatically converts it to the correct format for the printer can be very convenient.
 The first two characters of a PostScript(R) file are usually `%!`.
 A filter can detect those two characters.
 PostScript(R) files can be sent on to a PostScript(R) printer unchanged.
 Text files can be converted to PostScript(R) with Enscript as shown earlier.
 Create [.filename]#/usr/local/libexec/psif# with these contents:
 
 [.programlisting]
 ....
 #!/bin/sh
 #
 #  psif - Print PostScript or plain text on a PostScript printer
 #
 IFS="" read -r first_line
 first_two_chars=`expr "$first_line" : '\(..\)'`
 
 case "$first_two_chars" in
 %!)
     # %! : PostScript job, print it.
     echo "$first_line" && cat && exit 0
     exit 2
     ;;
 *)
     # otherwise, format with enscript
     ( echo "$first_line"; cat ) | /usr/local/bin/enscript -o - && exit 0
     exit 2
     ;;
 esac
 ....
 
 Set the permissions and make it executable:
 
 [source,shell]
 ....
 # chmod 555 /usr/local/libexec/psif
 ....
 
 Modify [.filename]#/etc/printcap# to use this new input filter:
 
 [.programlisting]
 ....
 :if=/usr/local/libexec/psif:\
 ....
 
 Test the filter by printing PostScript(R) and plain text files.
 
 [[printing-lpd-filters-othersmart]]
 ==== Other Smart Filters
 
 Writing a filter that detects many different types of input and formats them correctly is challenging.
 package:print/apsfilter[] from the Ports Collection is a smart "magic" filter that detects dozens of file types and automatically converts them to the `PDL` understood by the printer.
 See http://www.apsfilter.org[] for more details.
 
 [[printing-lpd-queues]]
 === Multiple Queues
 
 The entries in [.filename]#/etc/printcap# are really definitions of _queues_.
 There can be more than one queue for a single printer.
 When combined with filters, multiple queues provide users more control over how their jobs are printed.
 
 As an example, consider a networked PostScript(R) laser printer in an office.
 Most users want to print plain text, but a few advanced users want to be able to print PostScript(R) files directly.
 Two entries can be created for the same printer in [.filename]#/etc/printcap#:
 
 [.programlisting]
 ....
 textprinter:\
 	:lp=9100@officelaser:\
 	:sh:\
 	:mx#0:\
 	:sd=/var/spool/lpd/textprinter:\
 	:if=/usr/local/libexec/enscript:\
 	:lf=/var/log/lpd-errs:
 
 psprinter:\
 	:lp=9100@officelaser:\
 	:sh:\
 	:mx#0:\
 	:sd=/var/spool/lpd/psprinter:\
 	:lf=/var/log/lpd-errs:
 ....
 
 Documents sent to `textprinter` will be formatted by the [.filename]#/usr/local/libexec/enscript# filter shown in an earlier example.
 Advanced users can print PostScript(R) files on `psprinter`, where no filtering is done.
 
 This multiple queue technique can be used to provide direct access to all kinds of printer features.
 A printer with a duplexer could use two queues, one for ordinary single-sided printing, and one with a filter that sends the command sequence to enable double-sided printing and then sends the incoming file.
 
 [[printing-lpd-monitor]]
 === Monitoring and Controlling Printing
 
 Several utilities are available to monitor print jobs and check and control printer operation.
 
 [[printing-lpd-monitor-lpq]]
 ==== man:lpq[1]
 
 man:lpq[1] shows the status of a user's print jobs.
 Print jobs from other users are not shown.
 
 Show the current user's pending jobs on a single printer:
 
 [source,shell]
 ....
 % lpq -Plp
 Rank   Owner      Job  Files                                 Total Size
 1st    jsmith     0    (standard input)                      12792 bytes
 ....
 
 Show the current user's pending jobs on all printers:
 
 [source,shell]
 ....
 % lpq -a
 lp:
 Rank   Owner      Job  Files                                 Total Size
 1st    jsmith     1    (standard input)                      27320 bytes
 
 laser:
 Rank   Owner      Job  Files                                 Total Size
 1st    jsmith     287  (standard input)                      22443 bytes
 ....
 
 [[printing-lpd-monitor-lprm]]
 ==== man:lprm[1]
 
 man:lprm[1] is used to remove print jobs.
 Normal users are only allowed to remove their own jobs.
 `root` can remove any or all jobs.
 
 Remove all pending jobs from a printer:
 
 [source,shell]
 ....
 # lprm -Plp -
 dfA002smithy dequeued
 cfA002smithy dequeued
 dfA003smithy dequeued
 cfA003smithy dequeued
 dfA004smithy dequeued
 cfA004smithy dequeued
 ....
 
 Remove a single job from a printer.
 man:lpq[1] is used to find the job number.
 
 [source,shell]
 ....
 % lpq
 Rank   Owner      Job  Files                                 Total Size
 1st    jsmith     5    (standard input)                      12188 bytes
 
 % lprm -Plp 5
 dfA005smithy dequeued
 cfA005smithy dequeued
 ....
 
 [[printing-lpd-monitor-lpc]]
 ==== man:lpc[8]
 
 man:lpc[8] is used to check and modify printer status.
 `lpc` is followed by a command and an optional printer name.
 `all` can be used instead of a specific printer name, and the command will be applied to all printers.
 Normal users can view status with man:lpc[8].
 Only `root` can use commands which modify printer status.
 
 Show the status of all printers:
 
 [source,shell]
 ....
 % lpc status all
 lp:
 	queuing is enabled
 	printing is enabled
 	1 entry in spool area
 	printer idle
 laser:
 	queuing is enabled
 	printing is enabled
 	1 entry in spool area
 	waiting for laser to come up
 ....
 
 Prevent a printer from accepting new jobs, then begin accepting new jobs again:
 
 [source,shell]
 ....
 # lpc disable lp
 lp:
 	queuing disabled
 # lpc enable lp
 lp:
 	queuing enabled
 ....
 
 Stop printing, but continue to accept new jobs.
 Then begin printing again:
 
 [source,shell]
 ....
 # lpc stop lp
 lp:
 	printing disabled
 # lpc start lp
 lp:
 	printing enabled
 	daemon started
 ....
 
 Restart a printer after some error condition:
 
 [source,shell]
 ....
 # lpc restart lp
 lp:
 	no daemon to abort
 	printing enabled
 	daemon restarted
 ....
 
 Turn the print queue off and disable printing, with a message to explain the problem to users:
 
 [source,shell]
 ....
 # lpc down lp Repair parts will arrive on Monday
 lp:
 	printer and queuing disabled
 	status message is now: Repair parts will arrive on Monday
 ....
 
 Re-enable a printer that is down:
 
 [source,shell]
 ....
 # lpc up lp
 lp:
 	printing enabled
 	daemon started
 ....
 
 See man:lpc[8] for more commands and options.
 
 [[printing-lpd-shared]]
 === Shared Printers
 
 Printers are often shared by multiple users in businesses and schools.
 Additional features are provided to make sharing printers more convenient.
 
 [[printing-shared-aliases]]
 ==== Aliases
 
 The printer name is set in the first line of the entry in [.filename]#/etc/printcap#.
 Additional names, or _aliases_, can be added after that name.
 Aliases are separated from the name and each other by vertical bars:
 
 [.programlisting]
 ....
 lp|repairsprinter|salesprinter:\
 ....
 
 Aliases can be used in place of the printer name.
 For example, users in the Sales department print to their printer with
 
 [source,shell]
 ....
 % lpr -Psalesprinter sales-report.txt
 ....
 
 Users in the Repairs department print to _their_ printer with
 
 [source,shell]
 ....
 % lpr -Prepairsprinter repairs-report.txt
 ....
 
 All of the documents print on that single printer.
 When the Sales department grows enough to need their own printer, the alias can be removed from the shared printer entry and used as the name of a new printer.
 Users in both departments continue to use the same commands, but the Sales documents are sent to the new printer.
 
 [[printing-shared-headers]]
 ==== Header Pages
 
 It can be difficult for users to locate their documents in the stack of pages produced by a busy shared printer.
 _Header pages_ were created to solve this problem.
 A header page with the user name and document name is printed before each print job.
 These pages are also sometimes called _banner_ or _separator_ pages.
 
 Enabling header pages differs depending on whether the printer is connected directly to the computer with a `USB`, parallel, or serial cable, or is connected remotely over a network.
 
 Header pages on directly-connected printers are enabled by removing the `:sh:\` (Suppress Header) line from the entry in [.filename]#/etc/printcap#. 
 These header pages only use line feed characters for new lines.
 Some printers will need the [.filename]#/usr/share/examples/printing/hpif# filter to prevent stairstepped text.
 The filter configures `PCL` printers to print both carriage returns and line feeds when a line feed is received.
 
 Header pages for network printers must be configured on the printer itself.
 Header page entries in [.filename]#/etc/printcap# are ignored.
 Settings are usually available from the printer front panel or a configuration web page accessible with a web browser.
 
 [[printing-lpd-references]]
 === References
 
 Example files: [.filename]#/usr/share/examples/printing/#.
 
 The _4.3BSD Line Printer Spooler Manual_, [.filename]#/usr/share/doc/smm/07.lpd/paper.ascii.gz#.
 
 Manual pages: man:printcap[5], man:lpd[8], man:lpr[1], man:lpc[8], man:lprm[1], man:lpq[1].
 
 [[printing-other]]
 == Other Printing Systems
 
 Several other printing systems are available in addition to the built-in man:lpd[8].
 These systems offer support for other protocols or additional features.
 
 [[printing-other-cups]]
 === CUPS (Common UNIX(R) Printing System)
 
 CUPS is a popular printing system available on many operating systems.
 Using CUPS on FreeBSD is documented in a separate article: link:{cups}[CUPS]
 
 [[printing-other-hplip]]
 === HPLIP
 
 Hewlett Packard provides a printing system that supports many of their inkjet and laser printers.
 The port is package:print/hplip[].
 The main web page is at https://developers.hp.com/hp-linux-imaging-and-printing[].
 The port handles all the installation details on FreeBSD.
 Configuration information is shown at https://developers.hp.com/hp-linux-imaging-and-printing/install[].
 
 [[printing-other-lprng]]
 === LPRng
 
 LPRng was developed as an enhanced alternative to man:lpd[8].
 The port is package:sysutils/LPRng[].
 For details and documentation, see http://www.lprng.com/[].
diff --git a/documentation/content/en/books/handbook/serialcomms/_index.adoc b/documentation/content/en/books/handbook/serialcomms/_index.adoc
index 631beb9749..7786405bb3 100644
--- a/documentation/content/en/books/handbook/serialcomms/_index.adoc
+++ b/documentation/content/en/books/handbook/serialcomms/_index.adoc
@@ -1,1209 +1,1209 @@
 ---
 title: Chapter 27. Serial Communications
 part: Part IV. Network Communication
 prev: books/handbook/partiv
 next: books/handbook/ppp-and-slip
 description: This chapter covers some of the ways serial communications can be used on FreeBSD
 tags: ["serial", "communications", "terminal", "modem", "console"]
 ---
 
 [[serialcomms]]
 = Serial Communications
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 27
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/serialcomms/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/serialcomms/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/serialcomms/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[serial-synopsis]]
 == Synopsis
 
 UNIX(R) has always had support for serial communications as the very first UNIX(R) machines relied on serial lines for user input and output.
 Things have changed a lot from the days when the average terminal consisted of a 10-character-per-second serial printer and a keyboard.
 This chapter covers some of the ways serial communications can be used on FreeBSD.
 
 After reading this chapter, you will know:
 
 * How to connect terminals to a FreeBSD system.
 * How to use a modem to dial out to remote hosts.
 * How to allow remote users to login to a FreeBSD system with a modem.
 * How to boot a FreeBSD system from a serial console.
 
 Before reading this chapter, you should:
 
 * Know how to crossref:kernelconfig[kernelconfig, configure and install a custom kernel].
 * Understand crossref:basics[basics, FreeBSD permissions and processes].
 * Have access to the technical manual for the serial hardware to be used with FreeBSD.
 
 [[serial]]
 == Serial Terminology and Hardware
 
 The following terms are often used in serial communications:
 
 bps::
 Bits per Second (bps) is the rate at which data is transmitted.
 
 DTE::
 Data Terminal Equipment (DTE) is one of two endpoints in a serial communication.
 An example would be a computer.
 
 DCE::
 Data Communications Equipment (DTE) is the other endpoint in a serial communication.
 Typically, it is a modem or serial terminal.
 
 RS-232::
 The original standard which defined hardware serial communications.
 It has since been renamed to TIA-232.
 
 When referring to communication data rates, this section does not use the term _baud_.
 Baud refers to the number of electrical state transitions made in a period of time, while bps is the correct term to use.
 
 To connect a serial terminal to a FreeBSD system, a serial port on the computer and the proper cable to connect to the serial device are needed.
 Users who are already familiar with serial hardware and cabling can safely skip this section.
 
 [[term-cables-null]]
 === Serial Cables and Ports
 
 There are several different kinds of serial cables.
 The two most common types are null-modem cables and standard RS-232 cables.
 The documentation for the hardware should describe the type of cable required.
 
 These two types of cables differ in how the wires are connected to the connector.
 Each wire represents a signal, with the defined signals summarized in <<serialcomms-signal-names>>.
 A standard serial cable passes all of the RS-232C signals straight through.
 For example, the "Transmitted Data" pin on one end of the cable goes to the "Transmitted Data" pin on the other end.
 This is the type of cable used to connect a modem to the FreeBSD system, and is also appropriate for some terminals.
 
 A null-modem cable switches the "Transmitted Data" pin of the connector on one end with the "Received Data" pin on the other end.
 The connector can be either a DB-25 or a DB-9.
 
 A null-modem cable can be constructed using the pin connections summarized in <<nullmodem-db25>>, <<nullmodem-db9>>, and <<nullmodem-db9-25>>.
 While the standard calls for a straight-through pin 1 to pin 1 "Protective Ground" line, it is often omitted.
 Some terminals work using only pins 2, 3, and 7, while others require different configurations.
 When in doubt, refer to the documentation for the hardware.
 
 [[serialcomms-signal-names]]
 .RS-232C Signal Names
 [cols="1,1", frame="none", options="header"]
 |===
 <| Acronyms
 <| Names
 
 |RD
 |Received Data
 
 |TD
 |Transmitted Data
 
 |DTR
 |Data Terminal Ready
 
 |DSR
 |Data Set Ready
 
 |DCD
 |Data Carrier Detect
 
 |SG
 |Signal Ground
 
 |RTS
 |Request to Send
 
 |CTS
 |Clear to Send
 |===
 
 [[nullmodem-db25]]
 .DB-25 to DB-25 Null-Modem Cable
 [cols="1,1,1,1,1", frame="none", options="header"]
 |===
 <| Signal
 <| Pin #
 | 
 <| Pin #
 <| Signal
 
 |SG
 |7
 |connects to
 |7
 |SG
 
 |TD
 |2
 |connects to
 |3
 |RD
 
 |RD
 |3
 |connects to
 |2
 |TD
 
 |RTS
 |4
 |connects to
 |5
 |CTS
 
 |CTS
 |5
 |connects to
 |4
 |RTS
 
 |DTR
 |20
 |connects to
 |6
 |DSR
 
 |DTR
 |20
 |connects to
 |8
 |DCD
 
 |DSR
 |6
 |connects to
 |20
 |DTR
 
 |DCD
 |8
 |connects to
 |20
 |DTR
 |===
 
 [[nullmodem-db9]]
 .DB-9 to DB-9 Null-Modem Cable
 [cols="1,1,1,1,1", frame="none", options="header"]
 |===
 <| Signal
 <| Pin #
 | 
 <| Pin #
 <| Signal
 
 |RD
 |2
 |connects to
 |3
 |TD
 
 |TD
 |3
 |connects to
 |2
 |RD
 
 |DTR
 |4
 |connects to
 |6
 |DSR
 
 |DTR
 |4
 |connects to
 |1
 |DCD
 
 |SG
 |5
 |connects to
 |5
 |SG
 
 |DSR
 |6
 |connects to
 |4
 |DTR
 
 |DCD
 |1
 |connects to
 |4
 |DTR
 
 |RTS
 |7
 |connects to
 |8
 |CTS
 
 |CTS
 |8
 |connects to
 |7
 |RTS
 |===
 
 [[nullmodem-db9-25]]
 .DB-9 to DB-25 Null-Modem Cable
 [cols="1,1,1,1,1", frame="none", options="header"]
 |===
 <| Signal
 <| Pin #
 | 
 <| Pin #
 <| Signal
 
 |RD
 |2
 |connects to
 |2
 |TD
 
 |TD
 |3
 |connects to
 |3
 |RD
 
 |DTR
 |4
 |connects to
 |6
 |DSR
 
 |DTR
 |4
 |connects to
 |8
 |DCD
 
 |SG
 |5
 |connects to
 |7
 |SG
 
 |DSR
 |6
 |connects to
 |20
 |DTR
 
 |DCD
 |1
 |connects to
 |20
 |DTR
 
 |RTS
 |7
 |connects to
 |5
 |CTS
 
 |CTS
 |8
 |connects to
 |4
 |RTS
 |===
 
 [NOTE]
 ====
 When one pin at one end connects to a pair of pins at the other end, it is usually implemented with one short wire between the pair of pins in their connector and a long wire to the other single pin.
 ====
 
 Serial ports are the devices through which data is transferred between the FreeBSD host computer and the terminal.
 Several kinds of serial ports exist.
 Before purchasing or constructing a cable, make sure it will fit the ports on the terminal and on the FreeBSD system.
 
 Most terminals have DB-25 ports.
 Personal computers may have DB-25 or DB-9 ports.
 A multiport serial card may have RJ-12 or RJ-45/ ports.
 See the documentation that accompanied the hardware for specifications on the kind of port or visually verify the type of port.
 
 In FreeBSD, each serial port is accessed through an entry in [.filename]#/dev#.
 There are two different kinds of entries:
 
 * Call-in ports are named [.filename]#/dev/ttyuN# where _N_ is the port number, starting from zero. If a terminal is connected to the first serial port ([.filename]#COM1#), use [.filename]#/dev/ttyu0# to refer to the terminal. If the terminal is on the second serial port ([.filename]#COM2#), use [.filename]#/dev/ttyu1#, and so forth. Generally, the call-in port is used for terminals. Call-in ports require that the serial line assert the "Data Carrier Detect" signal to work correctly.
 * Call-out ports are named [.filename]#/dev/cuauN# on FreeBSD versions 8.X and higher and [.filename]#/dev/cuadN# on FreeBSD versions 7.X and lower. Call-out ports are usually not used for terminals, but are used for modems. The call-out port can be used if the serial cable or the terminal does not support the "Data Carrier Detect" signal.
 
 FreeBSD also provides initialization devices ([.filename]#/dev/ttyuN.init# and [.filename]#/dev/cuauN.init# or [.filename]#/dev/cuadN.init#) and locking devices ([.filename]#/dev/ttyuN.lock# and [.filename]#/dev/cuauN.lock# or [.filename]#/dev/cuadN.lock#).
 The initialization devices are used to initialize communications port parameters each time a port is opened, such as `crtscts` for modems which use `RTS/CTS` signaling for flow control.
 The locking devices are used to lock flags on ports to prevent users or programs changing certain parameters.
 Refer to man:termios[4], man:sio[4], and man:stty[1] for information on terminal settings, locking and initializing devices, and setting terminal options, respectively.
 
 [[serial-hw-config]]
 === Serial Port Configuration
 
 By default, FreeBSD supports four serial ports which are commonly known as [.filename]#COM1#, [.filename]#COM2#, [.filename]#COM3#, and [.filename]#COM4#.
 FreeBSD also supports dumb multi-port serial interface cards, such as the BocaBoard 1008 and 2016, as well as more intelligent multi-port cards such as those made by Digiboard.
 However, the default kernel only looks for the standard [.filename]#COM# ports.
 
 To see if the system recognizes the serial ports, look for system boot messages that start with `uart`:
 
 [source,shell]
 ....
 # grep uart /var/run/dmesg.boot
 ....
 
 If the system does not recognize all of the needed serial ports, additional entries can be added to [.filename]#/boot/device.hints#.
 This file already contains `hint.uart.0.\*` entries for [.filename]#COM1# and `hint.uart.1.*` entries for [.filename]#COM2#.
 When adding a port entry for [.filename]#COM3# use `0x3E8`, and for [.filename]#COM4# use `0x2E8`.
 Common IRQ addresses are `5` for [.filename]#COM3# and `9` for [.filename]#COM4#.
 
 To determine the default set of terminal I/O settings used by the port, specify its device name.
 This example determines the settings for the call-in port on [.filename]#COM2#:
 
 [source,shell]
 ....
 # stty -a -f /dev/ttyu1
 ....
 
 System-wide initialization of serial devices is controlled by [.filename]#/etc/rc.d/serial#.
 This file affects the default settings of serial devices.
 To change the settings for a device, use `stty`.
 By default, the changed settings are in effect until the device is closed and when the device is reopened, it goes back to the default set.
 To permanently change the default set, open and adjust the settings of the initialization device.
 For example, to turn on `CLOCAL` mode, 8 bit communication, and `XON/XOFF` flow control for [.filename]#ttyu5#, type:
 
 [source,shell]
 ....
 # stty -f /dev/ttyu5.init clocal cs8 ixon ixoff
 ....
 
 To prevent certain settings from being changed by an application, make adjustments to the locking device.
 For example, to lock the speed of [.filename]#ttyu5# to 57600 bps, type:
 
 [source,shell]
 ....
 # stty -f /dev/ttyu5.lock 57600
 ....
 
 Now, any application that opens [.filename]#ttyu5# and tries to change the speed of the port will be stuck with 57600 bps.
 
 [[term]]
 == Terminals
 
 Terminals provide a convenient and low-cost way to access a FreeBSD system when not at the computer's console or on a connected network.
 This section describes how to use terminals with FreeBSD.
 
 The original UNIX(R) systems did not have consoles.
 Instead, users logged in and ran programs through terminals that were connected to the computer's serial ports.
 
 The ability to establish a login session on a serial port still exists in nearly every UNIX(R)-like operating system today, including FreeBSD.
 By using a terminal attached to an unused serial port, a user can log in and run any text program that can normally be run on the console or in an `xterm` window.
 
 Many terminals can be attached to a FreeBSD system.
 An older spare computer can be used as a terminal wired into a more powerful computer running FreeBSD.
 This can turn what might otherwise be a single-user computer into a powerful multiple-user system.
 
 FreeBSD supports three types of terminals:
 
 Dumb terminals::
 Dumb terminals are specialized hardware that connect to computers over serial lines.
 They are called "dumb" because they have only enough computational power to display, send, and receive text.
 No programs can be run on these devices. Instead, dumb terminals connect to a computer that runs the needed programs.
 +
 There are hundreds of kinds of dumb terminals made by many manufacturers, and just about any kind will work with FreeBSD.
 Some high-end terminals can even display graphics, but only certain software packages can take advantage of these advanced features.
 +
 Dumb terminals are popular in work environments where workers do not need access to graphical applications.
 
 Computers Acting as Terminals::
 Since a dumb terminal has just enough ability to display, send, and receive text, any spare computer can be a dumb terminal.
 All that is needed is the proper cable and some _terminal emulation_ software to run on the computer.
 +
 This configuration can be useful.
 For example, if one user is busy working at the FreeBSD system's console, another user can do some text-only work at the same time from a less powerful personal computer hooked up as a terminal to the FreeBSD system.
 +
 There are at least two utilities in the base-system of FreeBSD that can be used to work through a serial connection: man:cu[1] and man:tip[1].
 +
 For example, to connect from a client system that runs FreeBSD to the serial connection of another system:
 +
 [source,shell]
 ....
 # cu -l /dev/cuauN
 ....
 +
 Ports are numbered starting from zero.
 This means that [.filename]#COM1# is [.filename]#/dev/cuau0#.
 +
 Additional programs are available through the Ports Collection, such as package:comms/minicom[].
 
 X Terminals::
 X terminals are the most sophisticated kind of terminal available.
 Instead of connecting to a serial port, they usually connect to a network like Ethernet.
 Instead of being relegated to text-only applications, they can display any Xorg application.
 +
 This chapter does not cover the setup, configuration, or use of X terminals.
 
 [[term-config]]
 === Terminal Configuration
 
 This section describes how to configure a FreeBSD system to enable a login session on a serial terminal.
 It assumes that the system recognizes the serial port to which the terminal is connected and that the terminal is connected with the correct cable.
 
 In FreeBSD, `init` reads [.filename]#/etc/ttys# and starts a `getty` process on the available terminals.
 The `getty` process is responsible for reading a login name and starting the `login` program.
 The ports on the FreeBSD system which allow logins are listed in [.filename]#/etc/ttys#.
 For example, the first virtual console, [.filename]#ttyv0#, has an entry in this file, allowing logins on the console.
 This file also contains entries for the other virtual consoles, serial ports, and pseudo-ttys.
 For a hardwired terminal, the serial port's [.filename]#/dev# entry is listed without the `/dev` part.
 For example, [.filename]#/dev/ttyv0# is listed as `ttyv0`.
 
 The default [.filename]#/etc/ttys# configures support for the first four serial ports, [.filename]#ttyu0# through [.filename]#ttyu3#:
 
 [.programlisting]
 ....
 ttyu0   "/usr/libexec/getty std.9600"   dialup  off secure
 ttyu1   "/usr/libexec/getty std.9600"   dialup  off secure
 ttyu2   "/usr/libexec/getty std.9600"   dialup  off secure
 ttyu3   "/usr/libexec/getty std.9600"   dialup  off secure
 ....
 
 When attaching a terminal to one of those ports, modify the default entry to set the required speed and terminal type, to turn the device `on` and, if needed, to change the port's `secure` setting.
 If the terminal is connected to another port, add an entry for the port.
 
 <<ex-etc-ttys>> configures two terminals in [.filename]#/etc/ttys#.
 The first entry configures a Wyse-50 connected to [.filename]#COM2#.
 The second entry configures an old computer running Procomm terminal software emulating a VT-100 terminal.
 The computer is connected to the sixth serial port on a multi-port serial card.
 
 [example]
 [[ex-etc-ttys]]
 .Configuring Terminal Entries
 ====
 
 [.programlisting]
 ....
 ttyu1  "/usr/libexec/getty std.38400"  wy50   on insecure 
 ttyu5   "/usr/libexec/getty std.19200"  vt100  on insecure
 ....
 
 The first field specifies the device name of the serial terminal.
 
 The second field tells `getty` to initialize and open the line, set the line speed, prompt for a user name, and then execute the `login` program.
 The optional _getty type_ configures characteristics on the terminal line, like bps rate and parity.
 The available getty types are listed in [.filename]#/etc/gettytab#.
 In almost all cases, the getty types that start with `std` will work for hardwired terminals as these entries ignore parity.
 There is a `std` entry for each bps rate from 110 to 115200.
 Refer to man:gettytab[5] for more information.
 When setting the getty type, make sure to match the communications settings used by the terminal.
 For this example, the Wyse-50 uses no parity and connects at 38400 bps.
 The computer uses no parity and connects at 19200 bps.
 
 The third field is the type of terminal.
 For dial-up ports, `unknown` or `dialup` is typically used since users may dial up with practically any type of terminal or software.
 Since the terminal type does not change for hardwired terminals, a real terminal type from [.filename]#/etc/termcap# can be specified.
 For this example, the Wyse-50 uses the real terminal type while the computer running Procomm is set to emulate a VT-100.
 
 The fourth field specifies if the port should be enabled.
 To enable logins on this port, this field must be set to `on`.
 
 The final field is used to specify whether the port is secure.
 Marking a port as `secure` means that it is trusted enough to allow `root` to login from that port.
 Insecure ports do not allow `root` logins.
 On an insecure port, users must login from unprivileged accounts and then use `su` or a similar mechanism to gain superuser privileges, as described in crossref:basics[users-superuser,“The Superuser Account”].
 For security reasons, it is recommended to change this setting to `insecure`.
 ====
 
 After making any changes to [.filename]#/etc/ttys#, send a SIGHUP (hangup) signal to the `init` process to force it to re-read its configuration file:
 
 [source,shell]
 ....
 # kill -HUP 1
 ....
 
 Since `init` is always the first process run on a system, it always has a process ID of `1`.
 
 If everything is set up correctly, all cables are in place, and the terminals are powered up, a `getty` process should now be running on each terminal and login prompts should be available on each terminal.
 
 [[term-debug]]
 === Troubleshooting the Connection
 
 Even with the most meticulous attention to detail, something could still go wrong while setting up a terminal.
 Here is a list of common symptoms and some suggested fixes.
 
 If no login prompt appears, make sure the terminal is plugged in and powered up.
 If it is a personal computer acting as a terminal, make sure it is running terminal emulation software on the correct serial port.
 
 Make sure the cable is connected firmly to both the terminal and the FreeBSD computer.
 Make sure it is the right kind of cable.
 
 Make sure the terminal and FreeBSD agree on the bps rate and parity settings.
 For a video display terminal, make sure the contrast and brightness controls are turned up.
 If it is a printing terminal, make sure paper and ink are in good supply.
 
 Use `ps` to make sure that a `getty` process is running and serving the terminal.
 For example, the following listing shows that a `getty` is running on the second serial port, [.filename]#ttyu1#, and is using the `std.38400` entry in [.filename]#/etc/gettytab#:
 
 [source,shell]
 ....
 # ps -axww|grep ttyu
 22189  d1  Is+    0:00.03 /usr/libexec/getty std.38400 ttyu1
 ....
 
 If no `getty` process is running, make sure the port is enabled in [.filename]#/etc/ttys#.
 Remember to run `kill -HUP 1` after modifying [.filename]#/etc/ttys#.
 
 If the `getty` process is running but the terminal still does not display a login prompt, or if it displays a prompt but will not accept typed input, the terminal or cable may not support hardware handshaking.
 Try changing the entry in [.filename]#/etc/ttys# from `std.38400` to `3wire.38400`, then run `kill -HUP 1` after modifying [.filename]#/etc/ttys#.
 The `3wire` entry is similar to `std`, but ignores hardware handshaking.
 The bps may also need to be reduced or software flow control enabled when using `3wire` to prevent buffer overflows.
 
 If garbage appears instead of a login prompt, make sure the terminal and FreeBSD agree on the bps rate and parity settings.
 Check the `getty` processes to make sure the correct _getty_ type is in use.
 If not, edit [.filename]#/etc/ttys# and run `kill -HUP 1`.
 
 If characters appear doubled and the password appears when typed, switch the terminal, or the terminal emulation software, from "half duplex" or "local echo" to "full duplex."
 
 [[dialup]]
 == Dial-in Service
 
 Configuring a FreeBSD system for dial-in service is similar to configuring terminals, except that modems are used instead of terminal devices.
 FreeBSD supports both external and internal modems.
 
 External modems are more convenient because they often can be configured via parameters stored in non-volatile RAM and they usually provide lighted indicators that display the state of important RS-232 signals, indicating whether the modem is operating properly.
 
 Internal modems usually lack non-volatile RAM, so their configuration may be limited to setting DIP switches.
 If the internal modem has any signal indicator lights, they are difficult to view when the system's cover is in place.
 
 When using an external modem, a proper cable is needed.
 A standard RS-232C serial cable should suffice.
 
 FreeBSD needs the RTS and CTS signals for flow control at speeds above 2400 bps, the CD signal to detect when a call has been answered or the line has been hung up, and the DTR signal to reset the modem after a session is complete.
 Some cables are wired without all of the needed signals, so if a login session does not go away when the line hangs up, there may be a problem with the cable.
 Refer to <<term-cables-null>> for more information about these signals.
 
 Like other UNIX(R)-like operating systems, FreeBSD uses the hardware signals to find out when a call has been answered or a line has been hung up and to hangup and reset the modem after a call.
 FreeBSD avoids sending commands to the modem or watching for status reports from the modem.
 
 FreeBSD supports the NS8250, NS16450, NS16550, and NS16550A-based RS-232C (CCITT V.24) communications interfaces.
 The 8250 and 16450 devices have single-character buffers.
 The 16550 device provides a 16-character buffer, which allows for better system performance.
 Bugs in plain 16550 devices prevent the use of the 16-character buffer, so use 16550A devices if possible.
 As single-character-buffer devices require more work by the operating system than the 16-character-buffer devices, 16550A-based serial interface cards are preferred.
 If the system has many active serial ports or will have a heavy load, 16550A-based cards are better for low-error-rate communications.
 
 The rest of this section demonstrates how to configure a modem to receive incoming connections, how to communicate with the modem, and offers some troubleshooting tips.
 
 [[dialup-ttys]]
 === Modem Configuration
 
 As with terminals, `init` spawns a `getty` process for each configured serial port used for dial-in connections.
 When a user dials the modem's line and the modems connect, the "Carrier Detect" signal is reported by the modem.
 The kernel notices that the carrier has been detected and instructs `getty` to open the port and display a `login:` prompt at the specified initial line speed.
 In a typical configuration, if garbage characters are received, usually due to the modem's connection speed being different than the configured speed, `getty` tries adjusting the line speeds until it receives reasonable characters.
 After the user enters their login name, `getty` executes `login`, which completes the login process by asking for the user's password and then starting the user's shell.
 
 There are two schools of thought regarding dial-up modems.
 One configuration method is to set the modems and systems so that no matter at what speed a remote user dials in, the dial-in RS-232 interface runs at a locked speed.
 The benefit of this configuration is that the remote user always sees a system login prompt immediately.
 The downside is that the system does not know what a user's true data rate is, so full-screen programs like Emacs will not adjust their screen-painting methods to make their response better for slower connections.
 
 The second method is to configure the RS-232 interface to vary its speed based on the remote user's connection speed.
 As `getty` does not understand any particular modem's connection speed reporting, it gives a `login:` message at an initial speed and watches the characters that come back in response.
 If the user sees junk, they should press kbd:[Enter] until they see a recognizable prompt.
 If the data rates do not match, `getty` sees anything the user types as junk, tries the next speed, and gives the `login:` prompt again.
 This procedure normally only takes a keystroke or two before the user sees a good prompt.
 This login sequence does not look as clean as the locked-speed method, but a user on a low-speed connection should receive better interactive response from full-screen programs.
 
 When locking a modem's data communications rate at a particular speed, no changes to [.filename]#/etc/gettytab# should be needed.
 However, for a matching-speed configuration, additional entries may be required in order to define the speeds to use for the modem.
 This example configures a 14.4 Kbps modem with a top interface speed of 19.2 Kbps using 8-bit, no parity connections.
 It configures `getty` to start the communications rate for a V.32bis connection at 19.2 Kbps, then cycles through 9600 bps, 2400 bps, 1200 bps, 300 bps, and back to 19.2 Kbps.
 Communications rate cycling is implemented with the `nx=` (next table) capability.
 Each line uses a `tc=` (table continuation) entry to pick up the rest of the settings for a particular data rate.
 
 [.programlisting]
 ....
 #
 # Additions for a V.32bis Modem
 #
 um|V300|High Speed Modem at 300,8-bit:\
         :nx=V19200:tc=std.300:
 un|V1200|High Speed Modem at 1200,8-bit:\
         :nx=V300:tc=std.1200:
 uo|V2400|High Speed Modem at 2400,8-bit:\
         :nx=V1200:tc=std.2400:
 up|V9600|High Speed Modem at 9600,8-bit:\
         :nx=V2400:tc=std.9600:
 uq|V19200|High Speed Modem at 19200,8-bit:\
         :nx=V9600:tc=std.19200:
 ....
 
 For a 28.8 Kbps modem, or to take advantage of compression on a 14.4 Kbps modem, use a higher communications rate, as seen in this example:
 
 [.programlisting]
 ....
 #
 # Additions for a V.32bis or V.34 Modem
 # Starting at 57.6 Kbps
 #
 vm|VH300|Very High Speed Modem at 300,8-bit:\
         :nx=VH57600:tc=std.300:
 vn|VH1200|Very High Speed Modem at 1200,8-bit:\
         :nx=VH300:tc=std.1200:
 vo|VH2400|Very High Speed Modem at 2400,8-bit:\
         :nx=VH1200:tc=std.2400:
 vp|VH9600|Very High Speed Modem at 9600,8-bit:\
         :nx=VH2400:tc=std.9600:
 vq|VH57600|Very High Speed Modem at 57600,8-bit:\
         :nx=VH9600:tc=std.57600:
 ....
 
 For a slow CPU or a heavily loaded system without 16550A-based serial ports, this configuration may produce `sio` "silo" errors at 57.6 Kbps.
 
 The configuration of [.filename]#/etc/ttys# is similar to <<ex-etc-ttys>>, but a different argument is passed to `getty` and `dialup` is used for the terminal type.
 Replace _xxx_ with the process `init` will run on the device:
 
 [.programlisting]
 ....
 ttyu0   "/usr/libexec/getty xxx"   dialup on
 ....
 
 The `dialup` terminal type can be changed.
 For example, setting `vt102` as the default terminal type allows users to use VT102 emulation on their remote systems.
 
 For a locked-speed configuration, specify the speed with a valid type listed in [.filename]#/etc/gettytab#.
 This example is for a modem whose port speed is locked at 19.2 Kbps:
 
 [.programlisting]
 ....
 ttyu0   "/usr/libexec/getty std.19200"   dialup on
 ....
 
 In a matching-speed configuration, the entry needs to reference the appropriate beginning "auto-baud" entry in [.filename]#/etc/gettytab#.
 To continue the example for a matching-speed modem that starts at 19.2 Kbps, use this entry:
 
 [.programlisting]
 ....
 ttyu0   "/usr/libexec/getty V19200"   dialup on
 ....
 
 After editing [.filename]#/etc/ttys#, wait until the modem is properly configured and connected before signaling `init`:
 
 [source,shell]
 ....
 # kill -HUP 1
 ....
 
 High-speed modems, like V.32, V.32bis, and V.34 modems, use hardware (`RTS/CTS`) flow control.
 Use `stty` to set the hardware flow control flag for the modem port.
 This example sets the `crtscts` flag on [.filename]#COM2#'s dial-in and dial-out initialization devices:
 
 [source,shell]
 ....
 # stty -f /dev/ttyu1.init crtscts
 # stty -f /dev/cuau1.init crtscts
 ....
 
 === Troubleshooting
 
 This section provides a few tips for troubleshooting a dial-up modem that will not connect to a FreeBSD system.
 
 Hook up the modem to the FreeBSD system and boot the system.
 If the modem has status indication lights, watch to see whether the modem's DTR indicator lights when the `login:` prompt appears on the system's console.
 If it lights up, that should mean that FreeBSD has started a `getty` process on the appropriate communications port and is waiting for the modem to accept a call.
 
 If the DTR indicator does not light, login to the FreeBSD system through the console and type `ps ax` to see if FreeBSD is running a `getty` process on the correct port:
 
 [source,shell]
 ....
   114 ??  I      0:00.10 /usr/libexec/getty V19200 ttyu0
 ....
 
 If the second column contains a `d0` instead of a `??` and the modem has not accepted a call yet, this means that `getty` has completed its open on the communications port.
 This could indicate a problem with the cabling or a misconfigured modem because `getty` should not be able to open the communications port until the carrier detect signal has been asserted by the modem.
 
 If no `getty` processes are waiting to open the port, double-check that the entry for the port is correct in [.filename]#/etc/ttys#.
 Also, check [.filename]#/var/log/messages# to see if there are any log messages from `init` or `getty`.
 
 Next, try dialing into the system.
 Be sure to use 8 bits, no parity, and 1 stop bit on the remote system.
 If a prompt does not appear right away, or the prompt shows garbage, try pressing kbd:[Enter] about once per second.
 If there is still no `login:` prompt, try sending a `BREAK`.
 When using a high-speed modem, try dialing again after locking the dialing modem's interface speed.
 
 If there is still no `login:` prompt, check [.filename]#/etc/gettytab# again and double-check that:
 
 * The initial capability name specified in the entry in [.filename]#/etc/ttys# matches the name of a capability in [.filename]#/etc/gettytab#.
 * Each `nx=` entry matches another [.filename]#gettytab# capability name.
 * Each `tc=` entry matches another [.filename]#gettytab# capability name.
 
 If the modem on the FreeBSD system will not answer, make sure that the modem is configured to answer the phone when DTR is asserted.
 If the modem seems to be configured correctly, verify that the DTR line is asserted by checking the modem's indicator lights.
 
 If it still does not work, try sending an email to the {freebsd-questions} describing the modem and the problem.
 
 [[dialout]]
 == Dial-out Service
 
 The following are tips for getting the host to connect over the modem to another computer.
 This is appropriate for establishing a terminal session with a remote host.
 
 This kind of connection can be helpful to get a file on the Internet if there are problems using PPP.
 If PPP is not working, use the terminal session to FTP the needed file.
 Then use zmodem to transfer it to the machine.
 
 [[hayes-unsupported]]
 === Using a Stock Hayes Modem
 
 A generic Hayes dialer is built into `tip`.
 Use `at=hayes` in [.filename]#/etc/remote#.
 
 The Hayes driver is not smart enough to recognize some of the advanced features of newer modems messages like `BUSY`, `NO DIALTONE`, or `CONNECT 115200`.
 Turn those messages off when using `tip` with `ATX0&W`.
 
 The dial timeout for `tip` is 60 seconds.
 The modem should use something less, or else `tip` will think there is a communication problem.
 Try `ATS7=45&W`.
 
 [[direct-at]]
 === Using `AT` Commands
 
 Create a "direct" entry in [.filename]#/etc/remote#.
 For example, if the modem is hooked up to the first serial port, [.filename]#/dev/cuau0#, use the following line:
 
 [.programlisting]
 ....
 cuau0:dv=/dev/cuau0:br#19200:pa=none
 ....
 
 Use the highest bps rate the modem supports in the `br` capability.
 Then, type `tip cuau0` to connect to the modem.
 
 Or, use `cu` as `root` with the following command:
 
 [source,shell]
 ....
 # cu -lline -sspeed
 ....
 
 _line_ is the serial port, such as [.filename]#/dev/cuau0#, and _speed_ is the speed, such as `57600`.
 When finished entering the AT commands, type `~.` to exit.
 
 [[gt-failure]]
 === The `@` Sign Does Not Work
 
 The `@` sign in the phone number capability tells `tip` to look in [.filename]#/etc/phones# for a phone number.
 But, the `@` sign is also a special character in capability files like [.filename]#/etc/remote#, so it needs to be escaped with a backslash:
 
 [.programlisting]
 ....
 pn=\@
 ....
 
 [[dial-command-line]]
 === Dialing from the Command Line
 
 Put a "generic" entry in [.filename]#/etc/remote#. For example:
 
 [.programlisting]
 ....
 tip115200|Dial any phone number at 115200 bps:\
         :dv=/dev/cuau0:br#115200:at=hayes:pa=none:du:
 tip57600|Dial any phone number at 57600 bps:\
         :dv=/dev/cuau0:br#57600:at=hayes:pa=none:du:
 ....
 
 This should now work:
 
 [source,shell]
 ....
 # tip -115200 5551234
 ....
 
 Users who prefer `cu` over `tip`, can use a generic `cu` entry:
 
 [.programlisting]
 ....
 cu115200|Use cu to dial any number at 115200bps:\
         :dv=/dev/cuau1:br#57600:at=hayes:pa=none:du:
 ....
 
 and type:
 
 [source,shell]
 ....
 # cu 5551234 -s 115200
 ....
 
 [[set-bps]]
 === Setting the bps Rate
 
 Put in an entry for `tip1200` or `cu1200`, but go ahead and use whatever bps rate is appropriate with the `br` capability.
 `tip` thinks a good default is 1200 bps which is why it looks for a `tip1200` entry.
 1200 bps does not have to be used, though.
 
 [[terminal-server]]
 === Accessing a Number of Hosts Through a Terminal Server
 
 Rather than waiting until connected and typing `CONNECT _host_` each time, use ``tip``'s `cm` capability.
 For example, these entries in [.filename]#/etc/remote# will let you type `tip pain` or `tip muffin` to connect to the hosts `pain` or `muffin`, and `tip deep13` to connect to the terminal server.
 
 [.programlisting]
 ....
 pain|pain.deep13.com|Forrester's machine:\
         :cm=CONNECT pain\n:tc=deep13:
 muffin|muffin.deep13.com|Frank's machine:\
         :cm=CONNECT muffin\n:tc=deep13:
 deep13:Gizmonics Institute terminal server:\
         :dv=/dev/cuau2:br#38400:at=hayes:du:pa=none:pn=5551234:
 ....
 
 [[tip-multiline]]
 === Using More Than One Line with `tip`
 
 This is often a problem where a university has several modem lines and several thousand students trying to use them.
 
 Make an entry in [.filename]#/etc/remote# and use `@` for the `pn` capability:
 
 [.programlisting]
 ....
 big-university:\
         :pn=\@:tc=dialout
 dialout:\
         :dv=/dev/cuau3:br#9600:at=courier:du:pa=none:
 ....
 
 Then, list the phone numbers in [.filename]#/etc/phones#:
 
 [.programlisting]
 ....
 big-university 5551111
 big-university 5551112
 big-university 5551113
 big-university 5551114
 ....
 
 `tip` will try each number in the listed order, then give up.
 To keep retrying, run `tip` in a `while` loop.
 
 [[multi-controlp]]
 === Using the Force Character
 
 kbd:[Ctrl+P] is the default "force" character, used to tell `tip` that the next character is literal data.
 The force character can be set to any other character with the `~s` escape, which means "set a variable."
 
 Type `~sforce=_single-char_` followed by a newline.
 _single-char_ is any single character.
 If _single-char_ is left out, then the force character is the null character, which is accessed by typing kbd:[Ctrl+2] or kbd:[Ctrl+Space].
 A pretty good value for _single-char_ is kbd:[Shift+Ctrl+6], which is only used on some terminal servers.
 
 To change the force character, specify the following in [.filename]#~/.tiprc#:
 
 [.programlisting]
 ....
 force=single-char
 ....
 
 [[uppercase]]
 === Upper Case Characters
 
 This happens when kbd:[Ctrl+A] is pressed, which is ``tip``'s "raise character", specially designed for people with broken caps-lock keys.
 Use `~s` to set `raisechar` to something reasonable.
 It can be set to be the same as the force character, if neither feature is used.
 
 Here is a sample [.filename]#~/.tiprc# for Emacs users who need to type kbd:[Ctrl+2] and kbd:[Ctrl+A]:
 
 [.programlisting]
 ....
 force=^^
 raisechar=^^
 ....
 
 The `^^` is kbd:[Shift+Ctrl+6].
 
 [[tip-filetransfer]]
 === File Transfers with `tip`
 
 When talking to another UNIX(R)-like operating system, files can be sent and received using `~p` (put) and `~t` (take).
 These commands run `cat` and `echo` on the remote system to accept and send files. The syntax is:
 `~p` local-file [ remote-file ]
 `~t` remote-file [ local-file ]
 
 There is no error checking, so another protocol, like zmodem, should probably be used.
 
 [[zmodem-tip]]
 === Using zmodem with `tip`?
 
 To receive files, start the sending program on the remote end.
 Then, type `~C rz` to begin receiving them locally.
 
 To send files, start the receiving program on the remote end.
 Then, type `~C sz _files_` to send them to the remote system.
 
 [[serialconsole-setup]]
 == Setting Up the Serial Console
 
 FreeBSD has the ability to boot a system with a dumb terminal on a serial port as a console.
 This configuration is useful for system administrators who wish to install FreeBSD on machines that have no keyboard or monitor attached, and developers who want to debug the kernel or device drivers.
 
 As described in crossref:boot[boot,The FreeBSD Booting Process], FreeBSD employs a three stage bootstrap.
 The first two stages are in the boot block code which is stored at the beginning of the FreeBSD slice on the boot disk.
 The boot block then loads and runs the boot loader as the third stage code.
 
 In order to set up booting from a serial console, the boot block code, the boot loader code, and the kernel need to be configured.
 
 [[serialconsole-howto-fast]]
 === Quick Serial Console Configuration
 
 This section provides a fast overview of setting up the serial console.
 This procedure can be used when the dumb terminal is connected to [.filename]#COM1#.
 
 [.procedure]
 .Procedure: Configuring a Serial Console on [.filename]#COM1#
 . Connect the serial cable to [.filename]#COM1# and the controlling terminal.
 . To configure boot messages to display on the serial console, issue the following command as the superuser:
 +
 [source,shell]
 ....
 # echo 'console="comconsole"' >> /boot/loader.conf
 ....
 
 . Edit [.filename]#/etc/ttys# and change `off` to `on` and `dialup` to `vt100` for the [.filename]#ttyu0# entry. Otherwise, a password will not be required to connect via the serial console, resulting in a potential security hole.
 . Reboot the system to see if the changes took effect.
 
 If a different configuration is required, see the next section for a more in-depth configuration explanation.
 
 [[serialconsole-howto]]
 === In-Depth Serial Console Configuration
 
 This section provides a more detailed explanation of the steps needed to setup a serial console in FreeBSD.
 
 [.procedure]
 .Procedure: Configuring a Serial Console
 . Prepare a serial cable.
-+ 
++
 Use either a null-modem cable or a standard serial cable and a null-modem adapter.
 See <<term-cables-null>> for a discussion on serial cables.
 . Unplug the keyboard.
-+ 
++
 Many systems probe for the keyboard during the Power-On Self-Test (POST) and will generate an error if the keyboard is not detected.
 Some machines will refuse to boot until the keyboard is plugged in.
-+ 
++
 If the computer complains about the error, but boots anyway, no further configuration is needed.
-+ 
++
 If the computer refuses to boot without a keyboard attached, configure the BIOS so that it ignores this error.
 Consult the motherboard's manual for details on how to do this.
 +
 [TIP]
 ====
 Try setting the keyboard to "Not installed" in the BIOS.
 This setting tells the BIOS not to probe for a keyboard at power-on so it should not complain if the keyboard is absent.
 If that option is not present in the BIOS, look for an "Halt on Error" option instead.
 Setting this to "All but Keyboard" or to "No Errors" will have the same effect.
 ====
-+ 
++
 If the system has a PS/2(R) mouse, unplug it as well.
 PS/2(R) mice share some hardware with the keyboard and leaving the mouse plugged in can fool the keyboard probe into thinking the keyboard is still there.
 +
 [NOTE]
 ====
 While most systems will boot without a keyboard, quite a few will not boot without a graphics adapter.
 Some systems can be configured to boot with no graphics adapter by changing the "graphics adapter" setting in the BIOS configuration to "Not installed". 
 Other systems do not support this option and will refuse to boot if there is no display hardware in the system.
 With these machines, leave some kind of graphics card plugged in, even if it is just a junky mono board.
 A monitor does not need to be attached.
 ====
 
 . Plug a dumb terminal, an old computer with a modem program, or the serial port on another UNIX(R) box into the serial port.
 . Add the appropriate `hint.sio.*` entries to [.filename]#/boot/device.hints# for the serial port. Some multi-port cards also require kernel configuration options. Refer to man:sio[4] for the required options and device hints for each supported serial port.
 . Create [.filename]#boot.config# in the root directory of the `a` partition on the boot drive.
-+ 
++
 This file instructs the boot block code how to boot the system.
 In order to activate the serial console, one or more of the following options are needed.
 When using multiple options, include them all on the same line:
 +
 `-h`:::
 Toggles between the internal and serial consoles.
 Use this to switch console devices.
 For instance, to boot from the internal (video) console, use `-h` to direct the boot loader and the kernel to use the serial port as its console device. 
 Alternatively, to boot from the serial port, use `-h` to tell the boot loader and the kernel to use the video display as the console instead.
 
 `-D`:::
 Toggles between the single and dual console configurations.
 In the single configuration, the console will be either the internal console (video display) or the serial port, depending on the state of `-h`.
 In the dual console configuration, both the video display and the serial port will become the console at the same time, regardless of the state of `-h`. 
 However, the dual console configuration takes effect only while the boot block is running.
 Once the boot loader gets control, the console specified by `-h` becomes the only console.
 
 `-P`:::
 Makes the boot block probe the keyboard. If no keyboard is found, the `-D` and `-h` options are automatically set.
 +
 [NOTE]
 ====
 Due to space constraints in the current version of the boot blocks, `-P` is capable of detecting extended keyboards only.
 Keyboards with less than 101 keys and without F11 and F12 keys may not be detected.
 Keyboards on some laptops may not be properly found because of this limitation.
 If this is the case, do not use `-P`.
 ====
-+ 
++
 Use either `-P` to select the console automatically or `-h` to activate the serial console.
 Refer to man:boot[8] and man:boot.config[5] for more details.
-+ 
++
 The options, except for `-P`, are passed to the boot loader.
 The boot loader will determine whether the internal video or the serial port should become the console by examining the state of `-h`.
 This means that if `-D` is specified but `-h` is not specified in [.filename]#/boot.config#, the serial port can be used as the console only during the boot block as the boot loader will use the internal video display as the console.
 . Boot the machine.
-+ 
++
 When FreeBSD starts, the boot blocks echo the contents of [.filename]#/boot.config# to the console. For example:
 +
 [source,shell]
 ....
 /boot.config: -P
 Keyboard: no
 ....
-+ 
++
 The second line appears only if `-P` is in [.filename]#/boot.config# and indicates the presence or absence of the keyboard.
 These messages go to either the serial or internal console, or both, depending on the option in [.filename]#/boot.config#:
 +
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 <| Options
 <| Message goes to
 
 |none
 |internal console
 
 |`-h`
 |serial console
 
 |`-D`
 |serial and internal consoles
 
 |`-Dh`
 |serial and internal consoles
 
 |`-P`, keyboard present
 |internal console
 
 |`-P`, keyboard absent
 |serial console
 |===
-+ 
++
 After the message, there will be a small pause before the boot blocks continue loading the boot loader and before any further messages are printed to the console.
 Under normal circumstances, there is no need to interrupt the boot blocks, but one can do so in order to make sure things are set up correctly.
-+ 
++
 Press any key, other than kbd:[Enter], at the console to interrupt the boot process.
 The boot blocks will then prompt for further action:
 +
 [source,shell]
 ....
 >> FreeBSD/i386 BOOT
 Default: 0:ad(0,a)/boot/loader
 boot:
 ....
-+ 
++
 Verify that the above message appears on either the serial or internal console, or both, according to the options in [.filename]#/boot.config#.
 If the message appears in the correct console, press kbd:[Enter] to continue the boot process.
-+ 
++
 If there is no prompt on the serial terminal, something is wrong with the settings.
 Enter `-h` then kbd:[Enter] or kbd:[Return] to tell the boot block (and then the boot loader and the kernel) to choose the serial port for the console.
 Once the system is up, go back and check what went wrong.
 
 During the third stage of the boot process, one can still switch between the internal console and the serial console by setting appropriate environment variables in the boot loader.
 See man:loader[8] for more information.
 
 [NOTE]
 ====
 This line in [.filename]#/boot/loader.conf# or [.filename]#/boot/loader.conf.local# configures the boot loader and the kernel to send their boot messages to the serial console, regardless of the options in [.filename]#/boot.config#:
 
 [.programlisting]
 ....
 console="comconsole"
 ....
 
 That line should be the first line of [.filename]#/boot/loader.conf# so that boot messages are displayed on the serial console as early as possible.
 
 If that line does not exist, or if it is set to `console="vidconsole"`, the boot loader and the kernel will use whichever console is indicated by `-h` in the boot block.
 See man:loader.conf[5] for more information.
 
 At the moment, the boot loader has no option equivalent to `-P` in the boot block, and there is no provision to automatically select the internal console and the serial console based on the presence of the keyboard.
 ====
 
 [TIP]
 ====
 While it is not required, it is possible to provide a `login` prompt over the serial line.
 To configure this, edit the entry for the serial port in [.filename]#/etc/ttys# using the instructions in <<term-config>>.
 If the speed of the serial port has been changed, change `std.9600` to match the new setting.
 ====
 
 === Setting a Faster Serial Port Speed
 
 By default, the serial port settings are 9600 baud, 8 bits, no parity, and 1 stop bit.
 To change the default console speed, use one of the following options:
 
 * Edit [.filename]#/etc/make.conf# and set `BOOT_COMCONSOLE_SPEED` to the new console speed.
 Then, recompile and install the boot blocks and the boot loader:
 +
 [source,shell]
 ....
 # cd /sys/boot
 # make clean
 # make
 # make install
 ....
-+ 
++
 If the serial console is configured in some other way than by booting with `-h`, or if the serial console used by the kernel is different from the one used by the boot blocks, add the following option, with the desired speed, to a custom kernel configuration file and compile a new kernel:
 +
 [.programlisting]
 ....
 options CONSPEED=19200
 ....
 
 * Add the `-S__19200__` boot option to [.filename]#/boot.config#, replacing `_19200_` with the speed to use.
 * Add the following options to [.filename]#/boot/loader.conf#. Replace `_115200_` with the speed to use.
 +
 [.programlisting]
 ....
 boot_multicons="YES"
 boot_serial="YES"
 comconsole_speed="115200"
 console="comconsole,vidconsole"
 ....
 
 [[serialconsole-ddb]]
 === Entering the DDB Debugger from the Serial Line
 
 To configure the ability to drop into the kernel debugger from the serial console, add the following options to a custom kernel configuration file and compile the kernel using the instructions in crossref:kernelconfig[kernelconfig,Configuring the FreeBSD Kernel].
 Note that while this is useful for remote diagnostics, it is also dangerous if a spurious BREAK is generated on the serial port.
 Refer to man:ddb[4] and man:ddb[8] for more information about the kernel debugger.
 
 [.programlisting]
 ....
 options BREAK_TO_DEBUGGER
 options DDB
 ....
diff --git a/documentation/content/en/books/handbook/virtualization/_index.adoc b/documentation/content/en/books/handbook/virtualization/_index.adoc
index 6966b6d53c..244633e075 100644
--- a/documentation/content/en/books/handbook/virtualization/_index.adoc
+++ b/documentation/content/en/books/handbook/virtualization/_index.adoc
@@ -1,1239 +1,1239 @@
 ---
 title: Chapter 22. Virtualization
 part: Part III. System Administration
 prev: books/handbook/filesystems
 next: books/handbook/l10n
 description: Virtualization software allows multiple operating systems to run simultaneously on the same computer
 tags: ["virtualization", "Parallels", "Virtual PC", "VMware", "VirtualBox", "bhyve", "XEN"]
 ---
 
 [[virtualization]]
 = Virtualization
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 22
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/virtualization/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/virtualization/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/virtualization/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[virtualization-synopsis]]
 == Synopsis
 
 Virtualization software allows multiple operating systems to run simultaneously on the same computer.
 Such software systems for PCs often involve a host operating system which runs the virtualization software and supports any number of guest operating systems.
 
 After reading this chapter, you will know:
 
 * The difference between a host operating system and a guest operating system.
 * How to install FreeBSD on an Intel(R)-based Apple(R) Mac(R) computer.
 * How to install FreeBSD on Microsoft(R) Windows(R) with Virtual PC.
 * How to install FreeBSD as a guest in bhyve.
 * How to tune a FreeBSD system for best performance under virtualization.
 
 Before reading this chapter, you should:
 
 * Understand the crossref:basics[basics,basics of UNIX(R) and FreeBSD].
 * Know how to crossref:bsdinstall[bsdinstall,install FreeBSD].
 * Know how to crossref:advanced-networking[advanced-networking,set up a network connection].
 * Know how to crossref:ports[ports,install additional third-party software].
 
 [[virtualization-guest-parallels]]
 == FreeBSD as a Guest on Parallels for Mac OS(R) X
 
 Parallels Desktop for Mac(R) is a commercial software product available for Intel(R) based Apple(R) Mac(R) computers running Mac OS(R) 10.4.6 or higher.
 FreeBSD is a fully supported guest operating system.
 Once Parallels has been installed on Mac OS(R) X, the user must configure a virtual machine and then install the desired guest operating system.
 
 [[virtualization-guest-parallels-install]]
 === Installing FreeBSD on Parallels/Mac OS(R) X
 
 The first step in installing FreeBSD on Parallels is to create a new virtual machine for installing FreeBSD.
 Select [.guimenuitem]#FreeBSD# as the menu:Guest OS Type[] when prompted:
 
 image::parallels-freebsd1.png[]
 
 Choose a reasonable amount of disk and memory depending on the plans for this virtual FreeBSD instance.
 4GB of disk space and 512MB of RAM work well for most uses of FreeBSD under Parallels:
 
 image::parallels-freebsd2.png[]
 
 image::parallels-freebsd3.png[]
 
 image::parallels-freebsd4.png[]
 
 image::parallels-freebsd5.png[]
 
 Select the type of networking and a network interface:
 
 image::parallels-freebsd6.png[]
 
 image::parallels-freebsd7.png[]
 
 Save and finish the configuration:
 
 image::parallels-freebsd8.png[]
 
 image::parallels-freebsd9.png[]
 
 After the FreeBSD virtual machine has been created, FreeBSD can be installed on it.
 This is best done with an official FreeBSD CD/DVD or with an ISO image downloaded from an official FTP site.
 Copy the appropriate ISO image to the local Mac(R) filesystem or insert a CD/DVD in the Mac(R)'s CD-ROM drive.
 Click on the disc icon in the bottom right corner of the FreeBSD Parallels window.
 This will bring up a window that can be used to associate the CD-ROM drive in the virtual machine with the ISO file on disk or with the real CD-ROM drive.
 
 image::parallels-freebsd11.png[]
 
 Once this association with the CD-ROM source has been made, reboot the FreeBSD virtual machine by clicking the reboot icon.
 Parallels will reboot with a special BIOS that first checks if there is a CD-ROM.
 
 image::parallels-freebsd10.png[]
 
 In this case it will find the FreeBSD installation media and begin a normal FreeBSD installation.
 Perform the installation, but do not attempt to configure Xorg at this time.
 
 image::parallels-freebsd12.png[]
 
 When the installation is finished, reboot into the newly installed FreeBSD virtual machine.
 
 image::parallels-freebsd13.png[]
 
 [[virtualization-guest-parallels-configure]]
 === Configuring FreeBSD on Parallels
 
 After FreeBSD has been successfully installed on Mac OS(R) X with Parallels, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.
 
 [.procedure]
 . Set Boot Loader Variables
-+ 
++
 The most important step is to reduce the `kern.hz` tunable to reduce the CPU utilization of FreeBSD under the Parallels environment.
 This is accomplished by adding the following line to [.filename]#/boot/loader.conf#:
 +
 [.programlisting]
 ....
 kern.hz=100
 ....
-+ 
++
 Without this setting, an idle FreeBSD Parallels guest will use roughly 15% of the CPU of a single processor iMac(R).
 After this change the usage will be closer to 5%.
 . Create a New Kernel Configuration File
-+ 
++
 All of the SCSI, FireWire, and USB device drivers can be removed from a custom kernel configuration file.
 Parallels provides a virtual network adapter used by the man:ed[4] driver, so all network devices except for man:ed[4] and man:miibus[4] can be removed from the kernel.
 . Configure Networking
-+ 
++
 The most basic networking setup uses DHCP to connect the virtual machine to the same local area network as the host Mac(R).
 This can be accomplished by adding `ifconfig_ed0="DHCP"` to [.filename]#/etc/rc.conf#.
 More advanced networking setups are described in crossref:advanced-networking[advanced-networking,Advanced Networking].
 
 [[virtualization-guest-virtualpc]]
 == FreeBSD as a Guest on Virtual PC for Windows(R)
 
 Virtual PC for Windows(R) is a Microsoft(R) software product available for free download.
 See this website for the http://www.microsoft.com/windows/downloads/virtualpc/sysreq.mspx[system requirements].
 Once Virtual PC has been installed on Microsoft(R) Windows(R), the user can configure a virtual machine and then install the desired guest operating system.
 
 [[virtualization-guest-virtualpc-install]]
 === Installing FreeBSD on Virtual PC
 
 The first step in installing FreeBSD on Virtual PC is to create a new virtual machine for installing FreeBSD.
 Select [.guimenuitem]#Create a virtual machine# when prompted:
 
 image::virtualpc-freebsd1.png[]
 
 image::virtualpc-freebsd2.png[]
 
 Select [.guimenuitem]#Other# as the [.guimenuitem]#Operating system# when prompted:
 
 image::virtualpc-freebsd3.png[]
 
 Then, choose a reasonable amount of disk and memory depending on the plans for this virtual FreeBSD instance.
 4GB of disk space and 512MB of RAM work well for most uses of FreeBSD under Virtual PC:
 
 image::virtualpc-freebsd4.png[]
 
 image::virtualpc-freebsd5.png[]
 
 Save and finish the configuration:
 
 image::virtualpc-freebsd6.png[]
 
 Select the FreeBSD virtual machine and click menu:Settings[], then set the type of networking and a network interface:
 
 image::virtualpc-freebsd7.png[]
 
 image::virtualpc-freebsd8.png[]
 
 After the FreeBSD virtual machine has been created, FreeBSD can be installed on it.
 This is best done with an official FreeBSD CD/DVD or with an ISO image downloaded from an official FTP site.
 Copy the appropriate ISO image to the local Windows(R) filesystem or insert a CD/DVD in the CD drive, then double click on the FreeBSD virtual machine to boot.
 Then, click menu:CD[] and choose menu:Capture ISO Image...[] on the Virtual PC window.
 This will bring up a window where the CD-ROM drive in the virtual machine can be associated with an ISO file on disk or with the real CD-ROM drive.
 
 image::virtualpc-freebsd9.png[]
 
 image::virtualpc-freebsd10.png[]
 
 Once this association with the CD-ROM source has been made, reboot the FreeBSD virtual machine by clicking menu:Action[] and menu:Reset[].
 Virtual PC will reboot with a special BIOS that first checks for a CD-ROM.
 
 image::virtualpc-freebsd11.png[]
 
 In this case it will find the FreeBSD installation media and begin a normal FreeBSD installation.
 Continue with the installation, but do not attempt to configure Xorg at this time.
 
 image::virtualpc-freebsd12.png[]
 
 When the installation is finished, remember to eject the CD/DVD or release the ISO image.
 Finally, reboot into the newly installed FreeBSD virtual machine.
 
 image::virtualpc-freebsd13.png[]
 
 [[virtualization-guest-virtualpc-configure]]
 === Configuring FreeBSD on Virtual PC
 
 After FreeBSD has been successfully installed on Microsoft(R) Windows(R) with Virtual PC, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.
 
 [.procedure]
 . Set Boot Loader Variables
-+ 
++
 The most important step is to reduce the `kern.hz` tunable to reduce the CPU utilization of FreeBSD under the Virtual PC environment.
 This is accomplished by adding the following line to [.filename]#/boot/loader.conf#:
 +
 [.programlisting]
 ....
 kern.hz=100
 ....
-+ 
++
 Without this setting, an idle FreeBSD Virtual PC guest OS will use roughly 40% of the CPU of a single processor computer.
 After this change, the usage will be closer to 3%.
 . Create a New Kernel Configuration File
-+ 
++
 All of the SCSI, FireWire, and USB device drivers can be removed from a custom kernel configuration file.
 Virtual PC provides a virtual network adapter used by the man:de[4] driver, so all network devices except for man:de[4] and man:miibus[4] can be removed from the kernel.
 . Configure Networking
-+ 
++
 The most basic networking setup uses DHCP to connect the virtual machine to the same local area network as the Microsoft(R) Windows(R) host.
 This can be accomplished by adding `ifconfig_de0="DHCP"` to [.filename]#/etc/rc.conf#.
 More advanced networking setups are described in crossref:advanced-networking[advanced-networking,Advanced Networking].
 
 [[virtualization-guest-vmware]]
 == FreeBSD as a Guest on VMware Fusion for Mac OS(R)
 
 VMware Fusion for Mac(R) is a commercial software product available for Intel(R) based Apple(R) Mac(R) computers running Mac OS(R) 10.4.9 or higher.
 FreeBSD is a fully supported guest operating system.
 Once VMware Fusion has been installed on Mac OS(R) X, the user can configure a virtual machine and then install the desired guest operating system.
 
 [[virtualization-guest-vmware-install]]
 === Installing FreeBSD on VMware Fusion
 
 The first step is to start VMware Fusion which will load the Virtual Machine Library.
 Click [.guimenuitem]#New# to create the virtual machine:
 
 image::vmware-freebsd01.png[]
 
 This will load the New Virtual Machine Assistant.
 Click [.guimenuitem]#Continue# to proceed:
 
 image::vmware-freebsd02.png[]
 
 Select [.guimenuitem]#Other# as the [.guimenuitem]#Operating System# and either [.guimenuitem]#FreeBSD# or [.guimenuitem]#FreeBSD 64-bit#, as the menu:Version[] when prompted:
 
 image::vmware-freebsd03.png[]
 
 Choose the name of the virtual machine and the directory where it should be saved:
 
 image::vmware-freebsd04.png[]
 
 Choose the size of the Virtual Hard Disk for the virtual machine:
 
 image::vmware-freebsd05.png[]
 
 Choose the method to install the virtual machine, either from an ISO image or from a CD/DVD:
 
 image::vmware-freebsd06.png[]
 
 Click [.guimenuitem]#Finish# and the virtual machine will boot:
 
 image::vmware-freebsd07.png[]
 
 Install FreeBSD as usual:
 
 image::vmware-freebsd08.png[]
 
 Once the install is complete, the settings of the virtual machine can be modified, such as memory usage:
 
 [NOTE]
 ====
 The System Hardware settings of the virtual machine cannot be modified while the virtual machine is running.
 ====
 
 image::vmware-freebsd09.png[]
 
 The number of CPUs the virtual machine will have access to:
 
 image::vmware-freebsd10.png[]
 
 The status of the CD-ROM device.
 Normally the CD/DVD/ISO is disconnected from the virtual machine when it is no longer needed.
 
 image::vmware-freebsd11.png[]
 
 The last thing to change is how the virtual machine will connect to the network.
 To allow connections to the virtual machine from other machines besides the host, choose [.guimenuitem]#Connect directly to the physical network (Bridged)#.
 Otherwise, [.guimenuitem]#Share the host's internet connection (NAT)# is preferred so that the virtual machine can have access to the Internet, but the network cannot access the virtual machine.
 
 image::vmware-freebsd12.png[]
 
 After modifying the settings, boot the newly installed FreeBSD virtual machine.
 
 [[virtualization-guest-vmware-configure]]
 === Configuring FreeBSD on VMware Fusion
 
 After FreeBSD has been successfully installed on Mac OS(R) X with VMware Fusion, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.
 
 [.procedure]
 . Set Boot Loader Variables
-+ 
++
 The most important step is to reduce the `kern.hz` tunable to reduce the CPU utilization of FreeBSD under the VMware Fusion environment.
 This is accomplished by adding the following line to [.filename]#/boot/loader.conf#:
 +
 [.programlisting]
 ....
 kern.hz=100
 ....
-+ 
++
 Without this setting, an idle FreeBSD VMware Fusion guest will use roughly 15% of the CPU of a single processor iMac(R).
 After this change, the usage will be closer to 5%.
 . Create a New Kernel Configuration File
-+ 
++
 All of the FireWire, and USB device drivers can be removed from a custom kernel configuration file.
 VMware Fusion provides a virtual network adapter used by the man:em[4] driver, so all network devices except for man:em[4] can be removed from the kernel.
 . Configure Networking
-+ 
++
 The most basic networking setup uses DHCP to connect the virtual machine to the same local area network as the host Mac(R).
 This can be accomplished by adding `ifconfig_em0="DHCP"` to [.filename]#/etc/rc.conf#.
 More advanced networking setups are described in crossref:advanced-networking[advanced-networking,Advanced Networking].
 
 [[virtualization-guest-virtualbox]]
 == FreeBSD as a Guest on VirtualBox(TM)
 
 FreeBSD works well as a guest in VirtualBox(TM).
 The virtualization software is available for most common operating systems, including FreeBSD itself.
 
 The VirtualBox(TM) guest additions provide support for:
 
 * Clipboard sharing.
 * Mouse pointer integration.
 * Host time synchronization.
 * Window scaling.
 * Seamless mode.
 
 [NOTE]
 ====
 These commands are run in the FreeBSD guest.
 ====
 
 First, install the package:emulators/virtualbox-ose-additions[] package or port in the FreeBSD guest.
 This will install the port:
 
 [source,shell]
 ....
 # cd /usr/ports/emulators/virtualbox-ose-additions && make install clean
 ....
 
 Add these lines to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 vboxguest_enable="YES"
 vboxservice_enable="YES"
 ....
 
 If man:ntpd[8] or man:ntpdate[8] is used, disable host time synchronization:
 
 [.programlisting]
 ....
 vboxservice_flags="--disable-timesync"
 ....
 
 Xorg will automatically recognize the `vboxvideo` driver.
 It can also be manually entered in [.filename]#/etc/X11/xorg.conf#:
 
 [.programlisting]
 ....
 Section "Device"
 	Identifier "Card0"
 	Driver "vboxvideo"
 	VendorName "InnoTek Systemberatung GmbH"
 	BoardName "VirtualBox Graphics Adapter"
 EndSection
 ....
 
 To use the `vboxmouse` driver, adjust the mouse section in [.filename]#/etc/X11/xorg.conf#:
 
 [.programlisting]
 ....
 Section "InputDevice"
 	Identifier "Mouse0"
 	Driver "vboxmouse"
 EndSection
 ....
 
 HAL users should create the following [.filename]#/usr/local/etc/hal/fdi/policy/90-vboxguest.fdi# or copy it from [.filename]#/usr/local/share/hal/fdi/policy/10osvendor/90-vboxguest.fdi#:
 
 [.programlisting]
 ....
 <?xml version="1.0" encoding="utf-8"?>
 <!--
 # Sun VirtualBox
 # Hal driver description for the vboxmouse driver
 # $Id: chapter.xml,v 1.33 2012-03-17 04:53:52 eadler Exp $
 
 	Copyright (C) 2008-2009 Sun Microsystems, Inc.
 
 	This file is part of VirtualBox Open Source Edition (OSE, as
 	available from http://www.virtualbox.org. This file is free software;
 	you can redistribute it and/or modify it under the terms of the GNU
 	General Public License (GPL) as published by the Free Software
 	Foundation, in version 2 as it comes in the "COPYING" file of the
 	VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 	hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 
 	Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 	Clara, CA 95054 USA or visit http://www.sun.com if you need
 	additional information or have any questions.
 -->
 <deviceinfo version="0.2">
   <device>
     <match key="info.subsystem" string="pci">
       <match key="info.product" string="VirtualBox guest Service">
         <append key="info.capabilities" type="strlist">input</append>
 	<append key="info.capabilities" type="strlist">input.mouse</append>
         <merge key="input.x11_driver" type="string">vboxmouse</merge>
 	<merge key="input.device" type="string">/dev/vboxguest</merge>
       </match>
     </match>
   </device>
 </deviceinfo>
 ....
 
 Shared folders for file transfers between host and VM are accessible by mounting them using `mount_vboxvfs`.
 A shared folder can be created on the host using the VirtualBox GUI or via `vboxmanage`.
 For example, to create a shared folder called _myshare_ under [.filename]#/mnt/bsdboxshare# for the VM named _BSDBox_, run:
 
 [source,shell]
 ....
 # vboxmanage sharedfolder add 'BSDBox' --name myshare --hostpath /mnt/bsdboxshare
 ....
 
 Note that the shared folder name must not contain spaces.
 Mount the shared folder from within the guest system like this:
 
 [source,shell]
 ....
 # mount_vboxvfs -w myshare /mnt
 ....
 
 [[virtualization-host-virtualbox]]
 == FreeBSD as a Host with VirtualBox(TM)
 
 VirtualBox(TM) is an actively developed, complete virtualization package, that is available for most operating systems including Windows(R), Mac OS(R), Linux(R) and FreeBSD.
 It is equally capable of running Windows(R) or UNIX(R)-like guests.
 It is released as open source software, but with closed-source components available in a separate extension pack.
 These components include support for USB 2.0 devices.
 More information may be found on the http://www.virtualbox.org/wiki/Downloads[Downloads page of the VirtualBox(TM) wiki].
 Currently, these extensions are not available for FreeBSD.
 
 [[virtualization-virtualbox-install]]
 === Installing VirtualBox(TM)
 
 VirtualBox(TM) is available as a FreeBSD package or port in package:emulators/virtualbox-ose[].
 The port can be installed using these commands:
 
 [source,shell]
 ....
 # cd /usr/ports/emulators/virtualbox-ose
 # make install clean
 ....
 
 One useful option in the port's configuration menu is the `GuestAdditions` suite of programs.
 These provide a number of useful features in guest operating systems, like mouse pointer integration (allowing the mouse to be shared between host and guest without the need to press a special keyboard shortcut to switch) and faster video rendering, especially in Windows(R) guests.
 The guest additions are available in the menu:Devices[] menu, after the installation of the guest is finished.
 
 A few configuration changes are needed before VirtualBox(TM) is started for the first time.
 The port installs a kernel module in [.filename]#/boot/modules# which must be loaded into the running kernel:
 
 [source,shell]
 ....
 # kldload vboxdrv
 ....
 
 To ensure the module is always loaded after a reboot, add this line to [.filename]#/boot/loader.conf#:
 
 [.programlisting]
 ....
 vboxdrv_load="YES"
 ....
 
 To use the kernel modules that allow bridged or host-only networking, add this line to [.filename]#/etc/rc.conf# and reboot the computer:
 
 [.programlisting]
 ....
 vboxnet_enable="YES"
 ....
 
 The `vboxusers` group is created during installation of VirtualBox(TM).
 All users that need access to VirtualBox(TM) will have to be added as members of this group.
 `pw` can be used to add new members:
 
 [source,shell]
 ....
 # pw groupmod vboxusers -m yourusername
 ....
 
 The default permissions for [.filename]#/dev/vboxnetctl# are restrictive and need to be changed for bridged networking:
 
 [source,shell]
 ....
 # chown root:vboxusers /dev/vboxnetctl
 # chmod 0660 /dev/vboxnetctl
 ....
 
 To make this permissions change permanent, add these lines to [.filename]#/etc/devfs.conf#:
 
 [.programlisting]
 ....
 own     vboxnetctl root:vboxusers
 perm    vboxnetctl 0660
 ....
 
 To launch VirtualBox(TM), type from an Xorg session:
 
 [source,shell]
 ....
 % VirtualBox
 ....
 
 For more information on configuring and using VirtualBox(TM), refer to the http://www.virtualbox.org[official website].
 For FreeBSD-specific information and troubleshooting instructions, refer to the http://wiki.FreeBSD.org/VirtualBox[relevant page in the FreeBSD wiki].
 
 [[virtualization-virtualbox-usb-support]]
 === VirtualBox(TM) USB Support
 
 VirtualBox(TM) can be configured to pass USB devices through to the guest operating system.
 The host controller of the OSE version is limited to emulating USB 1.1 devices until the extension pack supporting USB 2.0 and 3.0 devices becomes available on FreeBSD.
 
 For VirtualBox(TM) to be aware of USB devices attached to the machine, the user needs to be a member of the `operator` group.
 
 [source,shell]
 ....
 # pw groupmod operator -m yourusername
 ....
 
 Then, add the following to [.filename]#/etc/devfs.rules#, or create this file if it does not exist yet:
 
 [.programlisting]
 ....
 [system=10]
 add path 'usb/*' mode 0660 group operator
 ....
 
 To load these new rules, add the following to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 devfs_system_ruleset="system"
 ....
 
 Then, restart devfs:
 
 [source,shell]
 ....
 # service devfs restart
 ....
 
 Restart the login session and VirtualBox(TM) for these changes to take effect, and create USB filters as necessary.
 
 [[virtualization-virtualbox-host-dvd-cd-access]]
 === VirtualBox(TM) Host DVD/CD Access
 
 Access to the host DVD/CD drives from guests is achieved through the sharing of the physical drives.
 Within VirtualBox(TM), this is set up from the Storage window in the Settings of the virtual machine.
 If needed, create an empty IDECD/DVD device first.
 Then choose the Host Drive from the popup menu for the virtual CD/DVD drive selection.
 A checkbox labeled `Passthrough` will appear. This allows the virtual machine to use the hardware directly.
 For example, audio CDs or the burner will only function if this option is selected.
 
 HAL needs to run for VirtualBox(TM)DVD/CD functions to work, so enable it in [.filename]#/etc/rc.conf# and start it if it is not already running:
 
 [.programlisting]
 ....
 hald_enable="YES"
 ....
 
 [source,shell]
 ....
 # service hald start
 ....
 
 In order for users to be able to use VirtualBox(TM)DVD/CD functions, they need access to [.filename]#/dev/xpt0#, [.filename]#/dev/cdN#, and [.filename]#/dev/passN#.
 This is usually achieved by making the user a member of `operator`.
 Permissions to these devices have to be corrected by adding these lines to [.filename]#/etc/devfs.conf#:
 
 [.programlisting]
 ....
 perm cd* 0660
 perm xpt0 0660
 perm pass* 0660
 ....
 
 [source,shell]
 ....
 # service devfs restart
 ....
 
 [[virtualization-host-bhyve]]
 == FreeBSD as a Host with bhyve
 
 The bhyveBSD-licensed hypervisor became part of the base system with FreeBSD 10.0-RELEASE.
 This hypervisor supports a number of guests, including FreeBSD, OpenBSD, and many Linux(R) distributions.
 By default, bhyve provides access to serial console and does not emulate a graphical console.
 Virtualization offload features of newer CPUs are used to avoid the legacy methods of translating instructions and manually managing memory mappings.
 
 The bhyve design requires a processor that supports Intel(R) Extended Page Tables (EPT) or AMD(R) Rapid Virtualization Indexing (RVI) or Nested Page Tables (NPT).
 Hosting Linux(R) guests or FreeBSD guests with more than one vCPU requires VMX unrestricted mode support (UG).
 Most newer processors, specifically the Intel(R) Core(TM) i3/i5/i7 and Intel(R) Xeon(TM) E3/E5/E7, support these features.
 UG support was introduced with Intel's Westmere micro-architecture.
 For a complete list of Intel(R) processors that support EPT, refer to https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=873&0_ExtendedPageTables=True[].
 RVI is found on the third generation and later of the AMD Opteron(TM) (Barcelona) processors.
 The easiest way to tell if a processor supports bhyve is to run `dmesg` or look in [.filename]#/var/run/dmesg.boot# for the `POPCNT` processor feature flag on the `Features2` line for AMD(R) processors or `EPT` and `UG` on the `VT-x` line for Intel(R) processors.
 
 [[virtualization-bhyve-prep]]
 === Preparing the Host
 
 The first step to creating a virtual machine in bhyve is configuring the host system.
 First, load the bhyve kernel module:
 
 [source,shell]
 ....
 # kldload vmm
 ....
 
 Then, create a [.filename]#tap# interface for the network device in the virtual machine to attach to.
 In order for the network device to participate in the network, also create a bridge interface containing the [.filename]#tap# interface and the physical interface as members.
 In this example, the physical interface is _igb0_:
 
 [source,shell]
 ....
 # ifconfig tap0 create
 # sysctl net.link.tap.up_on_open=1
 net.link.tap.up_on_open: 0 -> 1
 # ifconfig bridge0 create
 # ifconfig bridge0 addm igb0 addm tap0
 # ifconfig bridge0 up
 ....
 
 [[virtualization-bhyve-freebsd]]
 === Creating a FreeBSD Guest
 
 Create a file to use as the virtual disk for the guest machine.
 Specify the size and name of the virtual disk:
 
 [source,shell]
 ....
 # truncate -s 16G guest.img
 ....
 
 Download an installation image of FreeBSD to install:
 
 [source,shell]
 ....
 # fetch ftp://ftp.freebsd.org/pub/FreeBSD/releases/ISO-IMAGES/12.2/FreeBSD-12.2-RELEASE-amd64-bootonly.iso
 FreeBSD-12.2-RELEASE-amd64-bootonly.iso       100% of  230 MB  570 kBps 06m17s
 ....
 
 FreeBSD comes with an example script for running a virtual machine in bhyve.
 The script will start the virtual machine and run it in a loop, so it will automatically restart if it crashes.
 The script takes a number of options to control the configuration of the machine: `-c` controls the number of virtual CPUs, `-m` limits the amount of memory available to the guest, `-t` defines which [.filename]#tap# device to use, `-d` indicates which disk image to use, `-i` tells bhyve to boot from the CD image instead of the disk, and `-I` defines which CD image to use.
 The last parameter is the name of the virtual machine, used to track the running machines.
 This example starts the virtual machine in installation mode:
 
 [source,shell]
 ....
 # sh /usr/share/examples/bhyve/vmrun.sh -c 1 -m 1024M -t tap0 -d guest.img -i -I FreeBSD-12.2-RELEASE-amd64-bootonly.iso guestname
 ....
 
 The virtual machine will boot and start the installer.
 After installing a system in the virtual machine, when the system asks about dropping in to a shell at the end of the installation, choose btn:[Yes].
 
 Reboot the virtual machine.
 While rebooting the virtual machine causes bhyve to exit, the [.filename]#vmrun.sh# script runs `bhyve` in a loop and will automatically restart it.
 When this happens, choose the reboot option from the boot loader menu in order to escape the loop.
 Now the guest can be started from the virtual disk:
 
 [source,shell]
 ....
 # sh /usr/share/examples/bhyve/vmrun.sh -c 4 -m 1024M -t tap0 -d guest.img guestname
 ....
 
 [[virtualization-bhyve-linux]]
 === Creating a Linux(R) Guest
 
 In order to boot operating systems other than FreeBSD, the package:sysutils/grub2-bhyve[] port must be first installed.
 
 Next, create a file to use as the virtual disk for the guest machine:
 
 [source,shell]
 ....
 # truncate -s 16G linux.img
 ....
 
 Starting a virtual machine with bhyve is a two step process.
 First a kernel must be loaded, then the guest can be started.
 The Linux(R) kernel is loaded with package:sysutils/grub2-bhyve[].
 Create a [.filename]#device.map# that grub will use to map the virtual devices to the files on the host system:
 
 [.programlisting]
 ....
 (hd0) ./linux.img
 (cd0) ./somelinux.iso
 ....
 
 Use package:sysutils/grub2-bhyve[] to load the Linux(R) kernel from the ISO image:
 
 [source,shell]
 ....
 # grub-bhyve -m device.map -r cd0 -M 1024M linuxguest
 ....
 
 This will start grub.
 If the installation CD contains a [.filename]#grub.cfg#, a menu will be displayed.
 If not, the `vmlinuz` and `initrd` files must be located and loaded manually:
 
 [source,shell]
 ....
 grub> ls
 (hd0) (cd0) (cd0,msdos1) (host)
 grub> ls (cd0)/isolinux
 boot.cat boot.msg grub.conf initrd.img isolinux.bin isolinux.cfg memtest
 splash.jpg TRANS.TBL vesamenu.c32 vmlinuz
 grub> linux (cd0)/isolinux/vmlinuz
 grub> initrd (cd0)/isolinux/initrd.img
 grub> boot
 ....
 
 Now that the Linux(R) kernel is loaded, the guest can be started:
 
 [source,shell]
 ....
 # bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap0 -s 3:0,virtio-blk,./linux.img \
     -s 4:0,ahci-cd,./somelinux.iso -l com1,stdio -c 4 -m 1024M linuxguest
 ....
 
 The system will boot and start the installer.
 After installing a system in the virtual machine, reboot the virtual machine.
 This will cause bhyve to exit.
 The instance of the virtual machine needs to be destroyed before it can be started again:
 
 [source,shell]
 ....
 # bhyvectl --destroy --vm=linuxguest
 ....
 
 Now the guest can be started directly from the virtual disk.
 Load the kernel:
 
 [source,shell]
 ....
 # grub-bhyve -m device.map -r hd0,msdos1 -M 1024M linuxguest
 grub> ls
 (hd0) (hd0,msdos2) (hd0,msdos1) (cd0) (cd0,msdos1) (host)
 (lvm/VolGroup-lv_swap) (lvm/VolGroup-lv_root)
 grub> ls (hd0,msdos1)/
 lost+found/ grub/ efi/ System.map-2.6.32-431.el6.x86_64 config-2.6.32-431.el6.x
 86_64 symvers-2.6.32-431.el6.x86_64.gz vmlinuz-2.6.32-431.el6.x86_64
 initramfs-2.6.32-431.el6.x86_64.img
 grub> linux (hd0,msdos1)/vmlinuz-2.6.32-431.el6.x86_64 root=/dev/mapper/VolGroup-lv_root
 grub> initrd (hd0,msdos1)/initramfs-2.6.32-431.el6.x86_64.img
 grub> boot
 ....
 
 Boot the virtual machine:
 
 [source,shell]
 ....
 # bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap0 \
     -s 3:0,virtio-blk,./linux.img -l com1,stdio -c 4 -m 1024M linuxguest
 ....
 
 Linux(R) will now boot in the virtual machine and eventually present you with the login prompt.
 Login and use the virtual machine.
 When you are finished, reboot the virtual machine to exit bhyve.
 Destroy the virtual machine instance:
 
 [source,shell]
 ....
 # bhyvectl --destroy --vm=linuxguest
 ....
 
 [[virtualization-bhyve-uefi]]
 === Booting bhyve Virtual Machines with UEFI Firmware
 
 In addition to bhyveload and grub-bhyve, the bhyve hypervisor can also boot virtual machines using the UEFI userspace firmware.
 This option may support guest operating systems that are not supported by the other loaders.
 
 In order to make use of the UEFI support in bhyve, first obtain the UEFI firmware images.
 This can be done by installing package:sysutils/bhyve-firmware[] port or package.
 
 With the firmware in place, add the flags `-l bootrom,_/path/to/firmware_` to your bhyve command line.
 The actual bhyve command may look like this:
 
 [source,shell]
 ....
 # bhyve -AHP -s 0:0,hostbridge -s 1:0,lpc \
 -s 2:0,virtio-net,tap1 -s 3:0,virtio-blk,./disk.img \
 -s 4:0,ahci-cd,./install.iso -c 4 -m 1024M \
 -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI.fd \
 guest
 ....
 
 package:sysutils/bhyve-firmware[] also contains a CSM-enabled firmware, to boot guests with no UEFI support in legacy BIOS mode:
 
 [source,shell]
 ....
 # bhyve -AHP -s 0:0,hostbridge -s 1:0,lpc \
 -s 2:0,virtio-net,tap1 -s 3:0,virtio-blk,./disk.img \
 -s 4:0,ahci-cd,./install.iso -c 4 -m 1024M \
 -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI_CSM.fd \
 guest
 ....
 
 [[virtualization-bhyve-framebuffer]]
 === Graphical UEFI Framebuffer for bhyve Guests
 
 The UEFI firmware support is particularly useful with predominantly graphical guest operating systems such as Microsoft Windows(R).
 
 Support for the UEFI-GOP framebuffer may also be enabled with the `-s 29,fbuf,tcp=_0.0.0.0:5900_` flags.
 The framebuffer resolution may be configured with `w=_800_` and `h=_600_`, and bhyve can be instructed to wait for a VNC connection before booting the guest by adding `wait`.
 The framebuffer may be accessed from the host or over the network via the VNC protocol.
 Additionally, `-s 30,xhci,tablet` can be added to achieve precise mouse cursor synchronization with the host.
 
 The resulting bhyve command would look like this:
 
 [source,shell]
 ....
 # bhyve -AHP -s 0:0,hostbridge -s 31:0,lpc \
 -s 2:0,virtio-net,tap1 -s 3:0,virtio-blk,./disk.img \
 -s 4:0,ahci-cd,./install.iso -c 4 -m 1024M \
 -s 29,fbuf,tcp=0.0.0.0:5900,w=800,h=600,wait \
 -s 30,xhci,tablet \
 -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI.fd \
 guest
 ....
 
 Note, in BIOS emulation mode, the framebuffer will cease receiving updates once control is passed from firmware to guest operating system.
 
 [[virtualization-bhyve-zfs]]
 === Using ZFS with bhyve Guests
 
 If ZFS is available on the host machine, using ZFS volumes instead of disk image files can provide significant performance benefits for the guest VMs.
 A ZFS volume can be created by:
 
 [source,shell]
 ....
 # zfs create -V16G -o volmode=dev zroot/linuxdisk0
 ....
 
 When starting the VM, specify the ZFS volume as the disk drive:
 
 [source,shell]
 ....
 # bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap0 -s3:0,virtio-blk,/dev/zvol/zroot/linuxdisk0 \
     -l com1,stdio -c 4 -m 1024M linuxguest
 ....
 
 [[virtualization-bhyve-nmdm]]
 === Virtual Machine Consoles
 
 It is advantageous to wrap the bhyve console in a session management tool such as package:sysutils/tmux[] or package:sysutils/screen[] in order to detach and reattach to the console.
 It is also possible to have the console of bhyve be a null modem device that can be accessed with `cu`.
 To do this, load the [.filename]#nmdm# kernel module and replace `-l com1,stdio` with `-l com1,/dev/nmdm0A`.
 The [.filename]#/dev/nmdm# devices are created automatically as needed, where each is a pair, corresponding to the two ends of the null modem cable ([.filename]#/dev/nmdm0A# and [.filename]#/dev/nmdm0B#).
 See man:nmdm[4] for more information.
 
 [source,shell]
 ....
 # kldload nmdm
 # bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap0 -s 3:0,virtio-blk,./linux.img \
     -l com1,/dev/nmdm0A -c 4 -m 1024M linuxguest
 # cu -l /dev/nmdm0B
 Connected
 
 Ubuntu 13.10 handbook ttyS0
 
 handbook login:
 ....
 
 [[virtualization-bhyve-managing]]
 === Managing Virtual Machines
 
 A device node is created in [.filename]#/dev/vmm# for each virtual machine.
 This allows the administrator to easily see a list of the running virtual machines:
 
 [source,shell]
 ....
 # ls -al /dev/vmm
 total 1
 dr-xr-xr-x   2 root  wheel    512 Mar 17 12:19 ./
 dr-xr-xr-x  14 root  wheel    512 Mar 17 06:38 ../
 crw-------   1 root  wheel  0x1a2 Mar 17 12:20 guestname
 crw-------   1 root  wheel  0x19f Mar 17 12:19 linuxguest
 crw-------   1 root  wheel  0x1a1 Mar 17 12:19 otherguest
 ....
 
 A specified virtual machine can be destroyed using `bhyvectl`:
 
 [source,shell]
 ....
 # bhyvectl --destroy --vm=guestname
 ....
 
 [[virtualization-bhyve-onboot]]
 === Persistent Configuration
 
 In order to configure the system to start bhyve guests at boot time, the following configurations must be made in the specified files:
 
 [.procedure]
 . [.filename]#/etc/sysctl.conf#
 +
 [.programlisting]
 ....
 net.link.tap.up_on_open=1
 ....
 
 . [.filename]#/etc/rc.conf#
 +
 [.programlisting]
 ....
 cloned_interfaces="bridge0 tap0"
 ifconfig_bridge0="addm igb0 addm tap0"
 kld_list="nmdm vmm"
 ....
 
 [[virtualization-host-xen]]
 == FreeBSD as a Xen(TM)-Host
 
 Xen is a GPLv2-licensed https://en.wikipedia.org/wiki/Hypervisor#Classification[type 1 hypervisor] for Intel(R) and ARM(R) architectures.
 FreeBSD has included i386(TM) and AMD(R) 64-Bit https://wiki.xenproject.org/wiki/DomU[DomU] and https://en.wikipedia.org/wiki/Amazon_Elastic_Compute_Cloud[Amazon EC2] unprivileged domain (virtual machine) support since FreeBSD 8.0 and includes Dom0 control domain (host) support in FreeBSD 11.0.
 Support for para-virtualized (PV) domains has been removed from FreeBSD 11 in favor of hardware virtualized (HVM) domains, which provides better performance.
 
 Xen(TM) is a bare-metal hypervisor, which means that it is the first program loaded after the BIOS.
 A special privileged guest called the Domain-0 (`Dom0` for short) is then started.
 The Dom0 uses its special privileges to directly access the underlying physical hardware, making it a high-performance solution.
 It is able to access the disk controllers and network adapters directly.
 The Xen(TM) management tools to manage and control the Xen(TM) hypervisor are also used by the Dom0 to create, list, and destroy VMs.
 Dom0 provides virtual disks and networking for unprivileged domains, often called `DomU`.
 Xen(TM) Dom0 can be compared to the service console of other hypervisor solutions, while the DomU is where individual guest VMs are run.
 
 Xen(TM) can migrate VMs between different Xen(TM) servers.
 When the two xen hosts share the same underlying storage, the migration can be done without having to shut the VM down first.
 Instead, the migration is performed live while the DomU is running and there is no need to restart it or plan a downtime.
 This is useful in maintenance scenarios or upgrade windows to ensure that the services provided by the DomU are still provided.
 Many more features of Xen(TM) are listed on the https://wiki.xenproject.org/wiki/Category:Overview[Xen Wiki Overview page].
 Note that not all features are supported on FreeBSD yet.
 
 [[virtualization-host-xen-requirements]]
 === Hardware Requirements for Xen(TM) Dom0
 
 To run the Xen(TM) hypervisor on a host, certain hardware functionality is required.
 Hardware virtualized domains require Extended Page Table (http://en.wikipedia.org/wiki/Extended_Page_Table[EPT]) and Input/Output Memory Management Unit (http://en.wikipedia.org/wiki/List_of_IOMMU-supporting_hardware[IOMMU]) support in the host processor.
 
 [NOTE]
 ====
 In order to run a FreeBSD Xen(TM) Dom0 the box must be booted using legacy boot (BIOS).
 ====
 
 [[virtualization-host-xen-dom0-setup]]
 === Xen(TM) Dom0 Control Domain Setup
 
 Users of FreeBSD 11 should install the package:emulators/xen-kernel47[] and package:sysutils/xen-tools47[] packages that are based on Xen version 4.7. Systems running on FreeBSD-12.0 or newer can use Xen 4.11 provided by package:emulators/xen-kernel411[] and package:sysutils/xen-tools411[], respectively.
 
 Configuration files must be edited to prepare the host for the Dom0 integration after the Xen packages are installed.
 An entry to [.filename]#/etc/sysctl.conf# disables the limit on how many pages of memory are allowed to be wired.
 Otherwise, DomU VMs with higher memory requirements will not run.
 
 [source,shell]
 ....
 # echo 'vm.max_wired=-1' >> /etc/sysctl.conf
 ....
 
 Another memory-related setting involves changing [.filename]#/etc/login.conf#, setting the `memorylocked` option to `unlimited`.
 Otherwise, creating DomU domains may fail with `Cannot allocate memory` errors.
 After making the change to [.filename]#/etc/login.conf#, run `cap_mkdb` to update the capability database.
 See crossref:security[security-resourcelimits,"Resource Limits"] for details.
 
 [source,shell]
 ....
 # sed -i '' -e 's/memorylocked=64K/memorylocked=unlimited/' /etc/login.conf
 # cap_mkdb /etc/login.conf
 ....
 
 Add an entry for the Xen(TM) console to [.filename]#/etc/ttys#:
 
 [source,shell]
 ....
 # echo 'xc0     "/usr/libexec/getty Pc"         xterm   onifconsole  secure' >> /etc/ttys
 ....
 
 Selecting a Xen(TM) kernel in [.filename]#/boot/loader.conf# activates the Dom0.
 Xen(TM) also requires resources like CPU and memory from the host machine for itself and other DomU domains.
 How much CPU and memory depends on the individual requirements and hardware capabilities.
 In this example, 8 GB of memory and 4 virtual CPUs are made available for the Dom0.
 The serial console is also activated and logging options are defined.
 
 The following command is used for Xen 4.7 packages:
 
 [source,shell]
 ....
 # echo 'hw.pci.mcfg=0' >> /boot/loader.conf
 # echo 'if_tap_load="YES"' >> /boot/loader.conf
 # echo 'xen_kernel="/boot/xen"' >> /boot/loader.conf
 # echo 'xen_cmdline="dom0_mem=8192M dom0_max_vcpus=4 dom0pvh=1 console=com1,vga com1=115200,8n1 guest_loglvl=all loglvl=all"' >> /boot/loader.conf
 ....
 
 For Xen versions 4.11 and higher, the following command should be used instead:
 
 [source,shell]
 ....
 # echo 'if_tap_load="YES"' >> /boot/loader.conf
 # echo 'xen_kernel="/boot/xen"' >> /boot/loader.conf
 # echo 'xen_cmdline="dom0_mem=8192M dom0_max_vcpus=4 dom0=pvh console=com1,vga com1=115200,8n1 guest_loglvl=all loglvl=all"' >> /boot/loader.conf
 ....
 
 [TIP]
 ====
 
 Log files that Xen(TM) creates for the DomU VMs are stored in [.filename]#/var/log/xen#.
 Please be sure to check the contents of that directory if experiencing issues.
 ====
 
 Activate the xencommons service during system startup:
 
 [source,shell]
 ....
 # sysrc xencommons_enable=yes
 ....
 
 These settings are enough to start a Dom0-enabled system.
 However, it lacks network functionality for the DomU machines.
 To fix that, define a bridged interface with the main NIC of the system which the DomU VMs can use to connect to the network.
 Replace _em0_ with the host network interface name.
 
 [source,shell]
 ....
 # sysrc cloned_interfaces="bridge0"
 # sysrc ifconfig_bridge0="addm em0 SYNCDHCP"
 # sysrc ifconfig_em0="up"
 ....
 
 Restart the host to load the Xen(TM) kernel and start the Dom0.
 
 [source,shell]
 ....
 # reboot
 ....
 
 After successfully booting the Xen(TM) kernel and logging into the system again, the Xen(TM) management tool `xl` is used to show information about the domains.
 
 [source,shell]
 ....
 # xl list
 Name                                        ID   Mem VCPUs      State   Time(s)
 Domain-0                                     0  8192     4     r-----     962.0
 ....
 
 The output confirms that the Dom0 (called `Domain-0`) has the ID `0` and is running.
 It also has the memory and virtual CPUs that were defined in [.filename]#/boot/loader.conf# earlier.
 More information can be found in the https://www.xenproject.org/help/documentation.html[Xen(TM) Documentation].
 DomU guest VMs can now be created.
 
 [[virtualization-host-xen-domu-setup]]
 === Xen(TM) DomU Guest VM Configuration
 
 Unprivileged domains consist of a configuration file and virtual or physical hard disks.
 Virtual disk storage for the DomU can be files created by man:truncate[1] or ZFS volumes as described in crossref:zfs[zfs-zfs-volume,“Creating and Destroying Volumes”].
 In this example, a 20 GB volume is used.
 A VM is created with the ZFS volume, a FreeBSD ISO image, 1 GB of RAM and two virtual CPUs.
 The ISO installation file is retrieved with man:fetch[1] and saved locally in a file called [.filename]#freebsd.iso#.
 
 [source,shell]
 ....
 # fetch ftp://ftp.freebsd.org/pub/FreeBSD/releases/ISO-IMAGES/12.0/FreeBSD-12.0-RELEASE-amd64-bootonly.iso -o freebsd.iso
 ....
 
 A ZFS volume of 20 GB called [.filename]#xendisk0# is created to serve as the disk space for the VM.
 
 [source,shell]
 ....
 # zfs create -V20G -o volmode=dev zroot/xendisk0
 ....
 
 The new DomU guest VM is defined in a file.
 Some specific definitions like name, keymap, and VNC connection details are also defined.
 The following [.filename]#freebsd.cfg# contains a minimum DomU configuration for this example:
 
 [source,shell]
 ....
 # cat freebsd.cfg
 builder = "hvm" <.>
 name = "freebsd" <.>
 memory = 1024 <.>
 vcpus = 2 <.>
 vif = [ 'mac=00:16:3E:74:34:32,bridge=bridge0' ] <.>
 disk = [
 '/dev/zvol/tank/xendisk0,raw,hda,rw', <.>
 '/root/freebsd.iso,raw,hdc:cdrom,r' <.>
   ]
 vnc = 1 <.>
 vnclisten = "0.0.0.0"
 serial = "pty"
 usbdevice = "tablet"
 ....
 
 These lines are explained in more detail:
 
 <.> This defines what kind of virtualization to use. `hvm` refers to hardware-assisted virtualization or hardware virtual machine. Guest operating systems can run unmodified on CPUs with virtualization extensions, providing nearly the same performance as running on physical hardware. `generic` is the default value and creates a PV domain.
 <.> Name of this virtual machine to distinguish it from others running on the same Dom0. Required.
 <.> Quantity of RAM in megabytes to make available to the VM. This amount is subtracted from the hypervisor's total available memory, not the memory of the Dom0.
 <.> Number of virtual CPUs available to the guest VM. For best performance, do not create guests with more virtual CPUs than the number of physical CPUs on the host.
 <.> Virtual network adapter. This is the bridge connected to the network interface of the host. The `mac` parameter is the MAC address set on the virtual network interface. This parameter is optional, if no MAC is provided Xen(TM) will generate a random one.
 <.> Full path to the disk, file, or ZFS volume of the disk storage for this VM. Options and multiple disk definitions are separated by commas.
 <.> Defines the Boot medium from which the initial operating system is installed. In this example, it is the ISO image downloaded earlier. Consult the Xen(TM) documentation for other kinds of devices and options to set.
 <.> Options controlling VNC connectivity to the serial console of the DomU. In order, these are: active VNC support, define IP address on which to listen, device node for the serial console, and the input method for precise positioning of the mouse and other input methods. `keymap` defines which keymap to use, and is `english` by default.
 
 After the file has been created with all the necessary options, the DomU is created by passing it to `xl create` as a parameter.
 
 [source,shell]
 ....
 # xl create freebsd.cfg
 ....
 
 [NOTE]
 ====
 Each time the Dom0 is restarted, the configuration file must be passed to `xl create` again to re-create the DomU.
 By default, only the Dom0 is created after a reboot, not the individual VMs.
 The VMs can continue where they left off as they stored the operating system on the virtual disk.
 The virtual machine configuration can change over time (for example, when adding more memory).
 The virtual machine configuration files must be properly backed up and kept available to be able to re-create the guest VM when needed.
 ====
 
 The output of `xl list` confirms that the DomU has been created.
 
 [source,shell]
 ....
 # xl list
 Name                                        ID   Mem VCPUs      State   Time(s)
 Domain-0                                     0  8192     4     r-----  1653.4
 freebsd                                      1  1024     1     -b----   663.9
 ....
 
 To begin the installation of the base operating system, start the VNC client, directing it to the main network address of the host or to the IP address defined on the `vnclisten` line of [.filename]#freebsd.cfg#.
 After the operating system has been installed, shut down the DomU and disconnect the VNC viewer.
 Edit [.filename]#freebsd.cfg#, removing the line with the `cdrom` definition or commenting it out by inserting a `#` character at the beginning of the line.
 To load this new configuration, it is necessary to remove the old DomU with `xl destroy`, passing either the name or the id as the parameter.
 Afterwards, recreate it using the modified [.filename]*freebsd.cfg*.
 
 [source,shell]
 ....
 # xl destroy freebsd
 # xl create freebsd.cfg
 ....
 
 The machine can then be accessed again using the VNC viewer.
 This time, it will boot from the virtual disk where the operating system has been installed and can be used as a virtual machine.
 
 [[virtualization-host-xen-troubleshooting]]
 === Troubleshooting
 
 This section contains basic information in order to help troubleshoot issues found when using FreeBSD as a Xen(TM) host or guest.
 
 [[virtualization-host-xen-troubleshooting-host]]
 ==== Host Boot Troubleshooting
 
 Please note that the following troubleshooting tips are intended for Xen(TM) 4.11 or newer.
 If you are still using Xen(TM) 4.7 and having issues consider migrating to a newer version of Xen(TM).
 
 In order to troubleshoot host boot issues you will likely need a serial cable, or a debug USB cable.
 Verbose Xen(TM) boot output can be obtained by adding options to the `xen_cmdline` option found in [.filename]#loader.conf#.
 A couple of relevant debug options are:
 
 * `iommu=debug`: can be used to print additional diagnostic information about the iommu.
 * `dom0=verbose`: can be used to print additional diagnostic information about the dom0 build process.
 * `sync_console`: flag to force synchronous console output. Useful for debugging to avoid losing messages due to rate limiting. Never use this option in production environments since it can allow malicious guests to perform DoS attacks against Xen(TM) using the console.
 
 FreeBSD should also be booted in verbose mode in order to identify any issues.
 To activate verbose booting, run this command:
 
 [source,shell]
 ....
 # echo 'boot_verbose="YES"' >> /boot/loader.conf
 ....
 
 If none of these options help solving the problem, please send the serial boot log to mailto:freebsd-xen@FreeBSD.org[freebsd-xen@FreeBSD.org] and mailto:xen-devel@lists.xenproject.org[xen-devel@lists.xenproject.org] for further analysis.
 
 [[virtualization-host-xen-troubleshooting-guest]]
 ==== Guest Creation Troubleshooting
 
 Issues can also arise when creating guests, the following attempts to provide some help for those trying to diagnose guest creation issues.
 
 The most common cause of guest creation failures is the `xl` command spitting some error and exiting with a return code different than 0.
 If the error provided is not enough to help identify the issue, more verbose output can also be obtained from `xl` by using the `v` option repeatedly.
 
 [source,shell]
 ....
 # xl -vvv create freebsd.cfg
 Parsing config from freebsd.cfg
 libxl: debug: libxl_create.c:1693:do_domain_create: Domain 0:ao 0x800d750a0: create: how=0x0 callback=0x0 poller=0x800d6f0f0
 libxl: debug: libxl_device.c:397:libxl__device_disk_set_backend: Disk vdev=xvda spec.backend=unknown
 libxl: debug: libxl_device.c:432:libxl__device_disk_set_backend: Disk vdev=xvda, using backend phy
 libxl: debug: libxl_create.c:1018:initiate_domain_create: Domain 1:running bootloader
 libxl: debug: libxl_bootloader.c:328:libxl__bootloader_run: Domain 1:not a PV/PVH domain, skipping bootloader
 libxl: debug: libxl_event.c:689:libxl__ev_xswatch_deregister: watch w=0x800d96b98: deregister unregistered
 domainbuilder: detail: xc_dom_allocate: cmdline="", features=""
 domainbuilder: detail: xc_dom_kernel_file: filename="/usr/local/lib/xen/boot/hvmloader"
 domainbuilder: detail: xc_dom_malloc_filemap    : 326 kB
 libxl: debug: libxl_dom.c:988:libxl__load_hvm_firmware_module: Loading BIOS: /usr/local/share/seabios/bios.bin
 ...
 ....
 
 If the verbose output does not help diagnose the issue there are also QEMU and Xen(TM) toolstack logs in [.filename]#/var/log/xen#.
 Note that the name of the domain is appended to the log name, so if the domain is named `freebsd` you should find a [.filename]#/var/log/xen/xl-freebsd.log# and likely a [.filename]#/var/log/xen/qemu-dm-freebsd.log#.
 Both log files can contain useful information for debugging.
 If none of this helps solve the issue, please send the description of the issue you are facing and as much information as possible to mailto:freebsd-xen@FreeBSD.org[freebsd-xen@FreeBSD.org] and mailto:xen-devel@lists.xenproject.org[xen-devel@lists.xenproject.org] in order to get help.
diff --git a/documentation/content/en/books/handbook/zfs/_index.adoc b/documentation/content/en/books/handbook/zfs/_index.adoc
index c854c9b09c..f299f96726 100644
--- a/documentation/content/en/books/handbook/zfs/_index.adoc
+++ b/documentation/content/en/books/handbook/zfs/_index.adoc
@@ -1,2872 +1,2872 @@
 ---
 title: Chapter 20. The Z File System (ZFS)
 part: Part III. System Administration
 prev: books/handbook/geom
 next: books/handbook/filesystems
 description: The Z File System, or ZFS, is an advanced file system designed to overcome many of the major problems found in previous designs
 tags: ["ZFS", "filesystem", "administration", "zpool", "features", "terminology", "RAID-Z"]
 ---
 
 [[zfs]]
 = The Z File System (ZFS)
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 20
 
 ifeval::["{backend}" == "html5"]
 :imagesdir: ../../../../images/books/handbook/zfs/
 endif::[]
 
 ifeval::["{backend}" == "pdf"]
 :imagesdir: ../../../../static/images/books/handbook/zfs/
 endif::[]
 
 ifeval::["{backend}" == "epub3"]
 :imagesdir: ../../../../static/images/books/handbook/zfs/
 endif::[]
 
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 The _Z File System_, or ZFS, is an advanced file system designed to overcome many of the major problems found in previous designs.
 
 Originally developed at Sun(TM), ongoing open source ZFS development has moved to the http://open-zfs.org[OpenZFS Project].
 
 ZFS has three major design goals:
 
 * Data integrity: All data includes a <<zfs-term-checksum,checksum>> of the data. When data is written, the checksum is calculated and written along with it. When that data is later read back, the checksum is calculated again. If the checksums do not match, a data error has been detected. ZFS will attempt to automatically correct errors when data redundancy is available.
 * Pooled storage: physical storage devices are added to a pool, and storage space is allocated from that shared pool. Space is available to all file systems, and can be increased by adding new storage devices to the pool.
 * Performance: multiple caching mechanisms provide increased performance. <<zfs-term-arc,ARC>> is an advanced memory-based read cache. A second level of disk-based read cache can be added with <<zfs-term-l2arc,L2ARC>>, and disk-based synchronous write cache is available with <<zfs-term-zil,ZIL>>.
 
 A complete list of features and terminology is shown in <<zfs-term>>.
 
 [[zfs-differences]]
 == What Makes ZFS Different
 
 ZFS is significantly different from any previous file system because it is more than just a file system.
 Combining the traditionally separate roles of volume manager and file system provides ZFS with unique advantages.
 The file system is now aware of the underlying structure of the disks.
 Traditional file systems could only be created on a single disk at a time.
 If there were two disks then two separate file systems would have to be created.
 In a traditional hardware RAID configuration, this problem was avoided by presenting the operating system with a single logical disk made up of the space provided by a number of physical disks, on top of which the operating system placed a file system.
 Even in the case of software RAID solutions like those provided by GEOM, the UFS file system living on top of the RAID transform believed that it was dealing with a single device.
 ZFS's combination of the volume manager and the file system solves this and allows the creation of many file systems all sharing a pool of available storage.
 One of the biggest advantages to ZFS's awareness of the physical layout of the disks is that existing file systems can be grown automatically when additional disks are added to the pool.
 This new space is then made available to all of the file systems.
 ZFS also has a number of different properties that can be applied to each file system,
 giving many advantages to creating a number of different file systems and datasets rather than a single monolithic file system.
 
 [[zfs-quickstart]]
 == Quick Start Guide
 
 There is a startup mechanism that allows FreeBSD to mount ZFS pools during system initialization.
 To enable it, add this line to [.filename]#/etc/rc.conf#:
 
 [.programlisting]
 ....
 zfs_enable="YES"
 ....
 
 Then start the service:
 
 [source,shell]
 ....
 # service zfs start
 ....
 
 The examples in this section assume three SCSI disks with the device names [.filename]#da0#, [.filename]#da1#, and [.filename]#da2#.
 Users of SATA hardware should instead use [.filename]#ada# device names.
 
 [[zfs-quickstart-single-disk-pool]]
 === Single Disk Pool
 
 To create a simple, non-redundant pool using a single disk device:
 
 [source,shell]
 ....
 # zpool create example /dev/da0
 ....
 
 To view the new pool, review the output of `df`:
 
 [source,shell]
 ....
 # df
 Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
 /dev/ad0s1a   2026030  235230  1628718    13%    /
 devfs               1       1        0   100%    /dev
 /dev/ad0s1d  54098308 1032846 48737598     2%    /usr
 example      17547136       0 17547136     0%    /example
 ....
 
 This output shows that the `example` pool has been created and mounted.
 It is now accessible as a file system.
 Files can be created on it and users can browse it:
 
 [source,shell]
 ....
 # cd /example
 # ls
 # touch testfile
 # ls -al
 total 4
 drwxr-xr-x   2 root  wheel    3 Aug 29 23:15 .
 drwxr-xr-x  21 root  wheel  512 Aug 29 23:12 ..
 -rw-r--r--   1 root  wheel    0 Aug 29 23:15 testfile
 ....
 
 However, this pool is not taking advantage of any ZFS features.
 To create a dataset on this pool with compression enabled:
 
 [source,shell]
 ....
 # zfs create example/compressed
 # zfs set compression=gzip example/compressed
 ....
 
 The `example/compressed` dataset is now a ZFS compressed file system.
 Try copying some large files to [.filename]#/example/compressed#.
 
 Compression can be disabled with:
 
 [source,shell]
 ....
 # zfs set compression=off example/compressed
 ....
 
 To unmount a file system, use `zfs umount` and then verify with `df`:
 
 [source,shell]
 ....
 # zfs umount example/compressed
 # df
 Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
 /dev/ad0s1a   2026030  235232  1628716    13%    /
 devfs               1       1        0   100%    /dev
 /dev/ad0s1d  54098308 1032864 48737580     2%    /usr
 example      17547008       0 17547008     0%    /example
 ....
 
 To re-mount the file system to make it accessible again, use `zfs mount` and verify with `df`:
 
 [source,shell]
 ....
 # zfs mount example/compressed
 # df
 Filesystem         1K-blocks    Used    Avail Capacity  Mounted on
 /dev/ad0s1a          2026030  235234  1628714    13%    /
 devfs                      1       1        0   100%    /dev
 /dev/ad0s1d         54098308 1032864 48737580     2%    /usr
 example             17547008       0 17547008     0%    /example
 example/compressed  17547008       0 17547008     0%    /example/compressed
 ....
 
 The pool and file system may also be observed by viewing the output from `mount`:
 
 [source,shell]
 ....
 # mount
 /dev/ad0s1a on / (ufs, local)
 devfs on /dev (devfs, local)
 /dev/ad0s1d on /usr (ufs, local, soft-updates)
 example on /example (zfs, local)
 example/compressed on /example/compressed (zfs, local)
 ....
 
 After creation, ZFS datasets can be used like any file systems.
 However, many other features are available which can be set on a per-dataset basis.
 In the example below, a new file system called `data` is created.
 Important files will be stored here, so it is configured to keep two copies of each data block:
 
 [source,shell]
 ....
 # zfs create example/data
 # zfs set copies=2 example/data
 ....
 
 It is now possible to see the data and space utilization by issuing `df`:
 
 [source,shell]
 ....
 # df
 Filesystem         1K-blocks    Used    Avail Capacity  Mounted on
 /dev/ad0s1a          2026030  235234  1628714    13%    /
 devfs                      1       1        0   100%    /dev
 /dev/ad0s1d         54098308 1032864 48737580     2%    /usr
 example             17547008       0 17547008     0%    /example
 example/compressed  17547008       0 17547008     0%    /example/compressed
 example/data        17547008       0 17547008     0%    /example/data
 ....
 
 Notice that each file system on the pool has the same amount of available space.
 This is the reason for using `df` in these examples, to show that the file systems use only the amount of space they need and all draw from the same pool.
 ZFS eliminates concepts such as volumes and partitions, and allows multiple file systems to occupy the same pool.
 
 To destroy the file systems and then destroy the pool as it is no longer needed:
 
 [source,shell]
 ....
 # zfs destroy example/compressed
 # zfs destroy example/data
 # zpool destroy example
 ....
 
 [[zfs-quickstart-raid-z]]
 === RAID-Z
 
 Disks fail. One method of avoiding data loss from disk failure is to implement RAID.
 ZFS supports this feature in its pool design.
 RAID-Z pools require three or more disks but provide more usable space than mirrored pools.
 
 This example creates a RAID-Z pool, specifying the disks to add to the pool:
 
 [source,shell]
 ....
 # zpool create storage raidz da0 da1 da2
 ....
 
 [NOTE]
 ====
 Sun(TM) recommends that the number of devices used in a RAID-Z configuration be between three and nine.
 For environments requiring a single pool consisting of 10 disks or more, consider breaking it up into smaller RAID-Z groups.
 If only two disks are available and redundancy is a requirement, consider using a ZFS mirror.
 Refer to man:zpool[8] for more details.
 ====
 
 The previous example created the `storage` zpool.
 This example makes a new file system called `home` in that pool:
 
 [source,shell]
 ....
 # zfs create storage/home
 ....
 
 Compression and keeping extra copies of directories and files can be enabled:
 
 [source,shell]
 ....
 # zfs set copies=2 storage/home
 # zfs set compression=gzip storage/home
 ....
 
 To make this the new home directory for users, copy the user data to this directory and create the appropriate symbolic links:
 
 [source,shell]
 ....
 # cp -rp /home/* /storage/home
 # rm -rf /home /usr/home
 # ln -s /storage/home /home
 # ln -s /storage/home /usr/home
 ....
 
 Users data is now stored on the freshly-created [.filename]#/storage/home#.
 Test by adding a new user and logging in as that user.
 
 Try creating a file system snapshot which can be rolled back later:
 
 [source,shell]
 ....
 # zfs snapshot storage/home@08-30-08
 ....
 
 Snapshots can only be made of a full file system, not a single directory or file.
 
 The `@` character is a delimiter between the file system name or the volume name.
 If an important directory has been accidentally deleted, the file system can be backed up,
 then rolled back to an earlier snapshot when the directory still existed:
 
 [source,shell]
 ....
 # zfs rollback storage/home@08-30-08
 ....
 
 To list all available snapshots, run `ls` in the file system's [.filename]#.zfs/snapshot# directory.
 For example, to see the previously taken snapshot:
 
 [source,shell]
 ....
 # ls /storage/home/.zfs/snapshot
 ....
 
 It is possible to write a script to perform regular snapshots on user data.
 However, over time, snapshots can consume a great deal of disk space.
 The previous snapshot can be removed using the command:
 
 [source,shell]
 ....
 # zfs destroy storage/home@08-30-08
 ....
 
 After testing, [.filename]#/storage/home# can be made the real [.filename]#/home# using this command:
 
 [source,shell]
 ....
 # zfs set mountpoint=/home storage/home
 ....
 
 Run `df` and `mount` to confirm that the system now treats the file system as the real [.filename]#/home#:
 
 [source,shell]
 ....
 # mount
 /dev/ad0s1a on / (ufs, local)
 devfs on /dev (devfs, local)
 /dev/ad0s1d on /usr (ufs, local, soft-updates)
 storage on /storage (zfs, local)
 storage/home on /home (zfs, local)
 # df
 Filesystem   1K-blocks    Used    Avail Capacity  Mounted on
 /dev/ad0s1a    2026030  235240  1628708    13%    /
 devfs                1       1        0   100%    /dev
 /dev/ad0s1d   54098308 1032826 48737618     2%    /usr
 storage       26320512       0 26320512     0%    /storage
 storage/home  26320512       0 26320512     0%    /home
 ....
 
 This completes the RAID-Z configuration.
 Daily status updates about the file systems created can be generated as part of the nightly man:periodic[8] runs.
 Add this line to [.filename]#/etc/periodic.conf#:
 
 [.programlisting]
 ....
 daily_status_zfs_enable="YES"
 ....
 
 [[zfs-quickstart-recovering-raid-z]]
 === Recovering RAID-Z
 
 Every software RAID has a method of monitoring its `state`.
 The status of RAID-Z devices may be viewed with this command:
 
 [source,shell]
 ....
 # zpool status -x
 ....
 
 If all pools are <<zfs-term-online,Online>> and everything is normal, the message shows:
 
 [source,shell]
 ....
 all pools are healthy
 ....
 
 If there is an issue, perhaps a disk is in the <<zfs-term-offline,Offline>> state, the pool state will look similar to:
 
 [source,shell]
 ....
   pool: storage
  state: DEGRADED
 status: One or more devices has been taken offline by the administrator.
 	Sufficient replicas exist for the pool to continue functioning in a
 	degraded state.
 action: Online the device using 'zpool online' or replace the device with
 	'zpool replace'.
  scrub: none requested
 config:
 
 	NAME        STATE     READ WRITE CKSUM
 	storage     DEGRADED     0     0     0
 	  raidz1    DEGRADED     0     0     0
 	    da0     ONLINE       0     0     0
 	    da1     OFFLINE      0     0     0
 	    da2     ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 This indicates that the device was previously taken offline by the administrator with this command:
 
 [source,shell]
 ....
 # zpool offline storage da1
 ....
 
 Now the system can be powered down to replace [.filename]#da1#.
 When the system is back online, the failed disk can replaced in the pool:
 
 [source,shell]
 ....
 # zpool replace storage da1
 ....
 
 From here, the status may be checked again, this time without `-x` so that all pools are shown:
 
 [source,shell]
 ....
 # zpool status storage
  pool: storage
  state: ONLINE
  scrub: resilver completed with 0 errors on Sat Aug 30 19:44:11 2008
 config:
 
 	NAME        STATE     READ WRITE CKSUM
 	storage     ONLINE       0     0     0
 	  raidz1    ONLINE       0     0     0
 	    da0     ONLINE       0     0     0
 	    da1     ONLINE       0     0     0
 	    da2     ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 In this example, everything is normal.
 
 [[zfs-quickstart-data-verification]]
 === Data Verification
 
 ZFS uses checksums to verify the integrity of stored data.
 These are enabled automatically upon creation of file systems.
 
 [WARNING]
 ====
 Checksums can be disabled, but it is _not_ recommended! Checksums take very little storage space and provide data integrity.
 Many ZFS features will not work properly with checksums disabled.
 There is no noticeable performance gain from disabling these checksums.
 ====
 
 Checksum verification is known as _scrubbing_.
 Verify the data integrity of the `storage` pool with this command:
 
 [source,shell]
 ....
 # zpool scrub storage
 ....
 
 The duration of a scrub depends on the amount of data stored.
 Larger amounts of data will take proportionally longer to verify.
 Scrubs are very I/O intensive, and only one scrub is allowed to run at a time.
 After the scrub completes, the status can be viewed with `status`:
 
 [source,shell]
 ....
 # zpool status storage
  pool: storage
  state: ONLINE
  scrub: scrub completed with 0 errors on Sat Jan 26 19:57:37 2013
 config:
 
 	NAME        STATE     READ WRITE CKSUM
 	storage     ONLINE       0     0     0
 	  raidz1    ONLINE       0     0     0
 	    da0     ONLINE       0     0     0
 	    da1     ONLINE       0     0     0
 	    da2     ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 The completion date of the last scrub operation is displayed to help track when another scrub is required.
 Routine scrubs help protect data from silent corruption and ensure the integrity of the pool.
 
 Refer to man:zfs[8] and man:zpool[8] for other ZFS options.
 
 [[zfs-zpool]]
 == `zpool` Administration
 
 ZFS administration is divided between two main utilities.
 The `zpool` utility controls the operation of the pool and deals with adding, removing, replacing, and managing disks.
 The <<zfs-zfs,`zfs`>> utility deals with creating, destroying, and managing datasets, both <<zfs-term-filesystem,file systems>> and <<zfs-term-volume,volumes>>.
 
 [[zfs-zpool-create]]
 === Creating and Destroying Storage Pools
 
 Creating a ZFS storage pool (_zpool_) involves making a number of decisions that are relatively permanent because the structure of the pool cannot be changed after the pool has been created.
 The most important decision is what types of vdevs into which to group the physical disks.
 See the list of <<zfs-term-vdev,vdev types>> for details about the possible options.
 After the pool has been created, most vdev types do not allow additional disks to be added to the vdev.
 The exceptions are mirrors, which allow additional disks to be added to the vdev, and stripes, which can be upgraded to mirrors by attaching an additional disk to the vdev.
 Although additional vdevs can be added to expand a pool, the layout of the pool cannot be changed after pool creation.
 Instead, the data must be backed up and the pool destroyed and recreated.
 
 Create a simple mirror pool:
 
 [source,shell]
 ....
 # zpool create mypool mirror /dev/ada1 /dev/ada2
 # zpool status
   pool: mypool
  state: ONLINE
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada1    ONLINE       0     0     0
             ada2    ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 Multiple vdevs can be created at once.
 Specify multiple groups of disks separated by the vdev type keyword, `mirror` in this example:
 
 [source,shell]
 ....
 # zpool create mypool mirror /dev/ada1 /dev/ada2 mirror /dev/ada3 /dev/ada4
 # zpool status
   pool: mypool
  state: ONLINE
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada1    ONLINE       0     0     0
             ada2    ONLINE       0     0     0
           mirror-1  ONLINE       0     0     0
             ada3    ONLINE       0     0     0
             ada4    ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 Pools can also be constructed using partitions rather than whole disks.
 Putting ZFS in a separate partition allows the same disk to have other partitions for other purposes.
 In particular, partitions with bootcode and file systems needed for booting can be added.
 This allows booting from disks that are also members of a pool.
 There is no performance penalty on FreeBSD when using a partition rather than a whole disk.
 Using partitions also allows the administrator to _under-provision_ the disks, using less than the full capacity.
 If a future replacement disk of the same nominal size as the original actually has a slightly smaller capacity, the smaller partition will still fit, and the replacement disk can still be used.
 
 Create a <<zfs-term-vdev-raidz,RAID-Z2>> pool using partitions:
 
 [source,shell]
 ....
 # zpool create mypool raidz2 /dev/ada0p3 /dev/ada1p3 /dev/ada2p3 /dev/ada3p3 /dev/ada4p3 /dev/ada5p3
 # zpool status
   pool: mypool
  state: ONLINE
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           raidz2-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
             ada3p3  ONLINE       0     0     0
             ada4p3  ONLINE       0     0     0
             ada5p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 A pool that is no longer needed can be destroyed so that the disks can be reused.
 Destroying a pool involves first unmounting all of the datasets in that pool.
 If the datasets are in use, the unmount operation will fail and the pool will not be destroyed.
 The destruction of the pool can be forced with `-f`, but this can cause undefined behavior in applications which had open files on those datasets.
 
 [[zfs-zpool-attach]]
 === Adding and Removing Devices
 
 There are two cases for adding disks to a zpool: attaching a disk to an existing vdev with `zpool attach`, or adding vdevs to the pool with `zpool add`.
 Only some <<zfs-term-vdev,vdev types>> allow disks to be added to the vdev after creation.
 
 A pool created with a single disk lacks redundancy.
 Corruption can be detected but not repaired, because there is no other copy of the data.
 The <<zfs-term-copies,copies>> property may be able to recover from a small failure such as a bad sector,
 but does not provide the same level of protection as mirroring or RAID-Z.
 Starting with a pool consisting of a single disk vdev, `zpool attach` can be used to add an additional disk to the vdev, creating a mirror.
 `zpool attach` can also be used to add additional disks to a mirror group, increasing redundancy and read performance.
 If the disks being used for the pool are partitioned, replicate the layout of the first disk on to the second.
 `gpart backup` and `gpart restore` can be used to make this process easier.
 
 Upgrade the single disk (stripe) vdev _ada0p3_ to a mirror by attaching _ada1p3_:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           ada0p3    ONLINE       0     0     0
 
 errors: No known data errors
 # zpool attach mypool ada0p3 ada1p3
 Make sure to wait until resilver is done before rebooting.
 
 If you boot from pool 'mypool', you may need to update
 boot code on newly attached disk 'ada1p3'.
 
 Assuming you use GPT partitioning and 'da0' is your new boot disk
 you may use the following command:
 
         gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 da0
 # gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada1
 bootcode written to ada1
 # zpool status
   pool: mypool
  state: ONLINE
 status: One or more devices is currently being resilvered.  The pool will
         continue to function, possibly in a degraded state.
 action: Wait for the resilver to complete.
   scan: resilver in progress since Fri May 30 08:19:19 2014
         527M scanned out of 781M at 47.9M/s, 0h0m to go
         527M resilvered, 67.53% done
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0  (resilvering)
 
 errors: No known data errors
 # zpool status
   pool: mypool
  state: ONLINE
   scan: resilvered 781M in 0h0m with 0 errors on Fri May 30 08:15:58 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 When adding disks to the existing vdev is not an option, as for RAID-Z, an alternative method is to add another vdev to the pool.
 Additional vdevs provide higher performance, distributing writes across the vdevs. Each vdev is responsible for providing its own redundancy.
 It is possible, but discouraged, to mix vdev types, like `mirror` and `RAID-Z`.
 Adding a non-redundant vdev to a pool containing mirror or RAID-Z vdevs risks the data on the entire pool.
 Writes are distributed, so the failure of the non-redundant disk will result in the loss of a fraction of every block that has been written to the pool.
 
 Data is striped across each of the vdevs.
 For example, with two mirror vdevs, this is effectively a RAID 10 that stripes writes across two sets of mirrors.
 Space is allocated so that each vdev reaches 100% full at the same time.
 There is a performance penalty if the vdevs have different amounts of free space, as a disproportionate amount of the data is written to the less full vdev.
 
 When attaching additional devices to a boot pool, remember to update the bootcode.
 
 Attach a second mirror group ([.filename]#ada2p3# and [.filename]#ada3p3#) to the existing mirror:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
   scan: resilvered 781M in 0h0m with 0 errors on Fri May 30 08:19:35 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
 
 errors: No known data errors
 # zpool add mypool mirror ada2p3 ada3p3
 # gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada2
 bootcode written to ada2
 # gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada3
 bootcode written to ada3
 # zpool status
   pool: mypool
  state: ONLINE
   scan: scrub repaired 0 in 0h0m with 0 errors on Fri May 30 08:29:51 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
           mirror-1  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
             ada3p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 Currently, vdevs cannot be removed from a pool, and disks can only be removed from a mirror if there is enough remaining redundancy.
 If only one disk in a mirror group remains, it ceases to be a mirror and reverts to being a stripe, risking the entire pool if that remaining disk fails.
 
 Remove a disk from a three-way mirror group:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
   scan: scrub repaired 0 in 0h0m with 0 errors on Fri May 30 08:29:51 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
 
 errors: No known data errors
 # zpool detach mypool ada2p3
 # zpool status
   pool: mypool
  state: ONLINE
   scan: scrub repaired 0 in 0h0m with 0 errors on Fri May 30 08:29:51 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 [[zfs-zpool-status]]
 === Checking the Status of a Pool
 
 Pool status is important.
 If a drive goes offline or a read, write, or checksum error is detected, the corresponding error count increases.
 The `status` output shows the configuration and status of each device in the pool and the status of the entire pool.
 Actions that need to be taken and details about the last <<zfs-zpool-scrub,`scrub`>> are also shown.
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
   scan: scrub repaired 0 in 2h25m with 0 errors on Sat Sep 14 04:25:50 2013
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           raidz2-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
             ada3p3  ONLINE       0     0     0
             ada4p3  ONLINE       0     0     0
             ada5p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 [[zfs-zpool-clear]]
 === Clearing Errors
 
 When an error is detected, the read, write, or checksum counts are incremented.
 The error message can be cleared and the counts reset with `zpool clear _mypool_`.
 Clearing the error state can be important for automated scripts that alert the administrator when the pool encounters an error.
 Further errors may not be reported if the old errors are not cleared.
 
 [[zfs-zpool-replace]]
 === Replacing a Functioning Device
 
 There are a number of situations where it may be desirable to replace one disk with a different disk.
 When replacing a working disk, the process keeps the old disk online during the replacement.
 The pool never enters a <<zfs-term-degraded,degraded>> state, reducing the risk of data loss.
 `zpool replace` copies all of the data from the old disk to the new one.
 After the operation completes, the old disk is disconnected from the vdev.
 If the new disk is larger than the old disk, it may be possible to grow the zpool, using the new space.
 See <<zfs-zpool-online,Growing a Pool>>.
 
 Replace a functioning device in the pool:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
 
 errors: No known data errors
 # zpool replace mypool ada1p3 ada2p3
 Make sure to wait until resilver is done before rebooting.
 
 If you boot from pool 'zroot', you may need to update
 boot code on newly attached disk 'ada2p3'.
 
 Assuming you use GPT partitioning and 'da0' is your new boot disk
 you may use the following command:
 
         gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 da0
 # gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada2
 # zpool status
   pool: mypool
  state: ONLINE
 status: One or more devices is currently being resilvered.  The pool will
         continue to function, possibly in a degraded state.
 action: Wait for the resilver to complete.
   scan: resilver in progress since Mon Jun  2 14:21:35 2014
         604M scanned out of 781M at 46.5M/s, 0h0m to go
         604M resilvered, 77.39% done
 config:
 
         NAME             STATE     READ WRITE CKSUM
         mypool           ONLINE       0     0     0
           mirror-0       ONLINE       0     0     0
             ada0p3       ONLINE       0     0     0
             replacing-1  ONLINE       0     0     0
               ada1p3     ONLINE       0     0     0
               ada2p3     ONLINE       0     0     0  (resilvering)
 
 errors: No known data errors
 # zpool status
   pool: mypool
  state: ONLINE
   scan: resilvered 781M in 0h0m with 0 errors on Mon Jun  2 14:21:52 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 [[zfs-zpool-resilver]]
 === Dealing with Failed Devices
 
 When a disk in a pool fails, the vdev to which the disk belongs enters the <<zfs-term-degraded,degraded>> state.
 All of the data is still available, but performance may be reduced because missing data must be calculated from the available redundancy.
 To restore the vdev to a fully functional state, the failed physical device must be replaced.
 ZFS is then instructed to begin the <<zfs-term-resilver,resilver>> operation.
 Data that was on the failed device is recalculated from available redundancy and written to the replacement device.
 After completion, the vdev returns to <<zfs-term-online,online>> status.
 
 If the vdev does not have any redundancy, or if multiple devices have failed and there is not enough redundancy to compensate, the pool enters the <<zfs-term-faulted,faulted>> state.
 If a sufficient number of devices cannot be reconnected to the pool, the pool becomes inoperative and data must be restored from backups.
 
 When replacing a failed disk, the name of the failed disk is replaced with the GUID of the device.
 A new device name parameter for `zpool replace` is not required if the replacement device has the same device name.
 
 Replace a failed disk using `zpool replace`:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: DEGRADED
 status: One or more devices could not be opened.  Sufficient replicas exist for
         the pool to continue functioning in a degraded state.
 action: Attach the missing device and online it using 'zpool online'.
    see: http://illumos.org/msg/ZFS-8000-2Q
   scan: none requested
 config:
 
         NAME                    STATE     READ WRITE CKSUM
         mypool                  DEGRADED     0     0     0
           mirror-0              DEGRADED     0     0     0
             ada0p3              ONLINE       0     0     0
             316502962686821739  UNAVAIL      0     0     0  was /dev/ada1p3
 
 errors: No known data errors
 # zpool replace mypool 316502962686821739 ada2p3
 # zpool status
   pool: mypool
  state: DEGRADED
 status: One or more devices is currently being resilvered.  The pool will
         continue to function, possibly in a degraded state.
 action: Wait for the resilver to complete.
   scan: resilver in progress since Mon Jun  2 14:52:21 2014
         641M scanned out of 781M at 49.3M/s, 0h0m to go
         640M resilvered, 82.04% done
 config:
 
         NAME                        STATE     READ WRITE CKSUM
         mypool                      DEGRADED     0     0     0
           mirror-0                  DEGRADED     0     0     0
             ada0p3                  ONLINE       0     0     0
             replacing-1             UNAVAIL      0     0     0
               15732067398082357289  UNAVAIL      0     0     0  was /dev/ada1p3/old
               ada2p3                ONLINE       0     0     0  (resilvering)
 
 errors: No known data errors
 # zpool status
   pool: mypool
  state: ONLINE
   scan: resilvered 781M in 0h0m with 0 errors on Mon Jun  2 14:52:38 2014
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 [[zfs-zpool-scrub]]
 === Scrubbing a Pool
 
 It is recommended that pools be <<zfs-term-scrub,scrubbed>> regularly, ideally at least once every month.
 The `scrub` operation is very disk-intensive and will reduce performance while running.
 Avoid high-demand periods when scheduling `scrub` or use <<zfs-advanced-tuning-scrub_delay,`vfs.zfs.scrub_delay`>> to adjust the relative priority of the `scrub` to prevent it interfering with other workloads.
 
 [source,shell]
 ....
 # zpool scrub mypool
 # zpool status
   pool: mypool
  state: ONLINE
   scan: scrub in progress since Wed Feb 19 20:52:54 2014
         116G scanned out of 8.60T at 649M/s, 3h48m to go
         0 repaired, 1.32% done
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           raidz2-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
             ada3p3  ONLINE       0     0     0
             ada4p3  ONLINE       0     0     0
             ada5p3  ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 In the event that a scrub operation needs to be cancelled, issue `zpool scrub -s _mypool_`.
 
 [[zfs-zpool-selfheal]]
 === Self-Healing
 
 The checksums stored with data blocks enable the file system to _self-heal_.
 This feature will automatically repair data whose checksum does not match the one recorded on another device that is part of the storage pool.
 For example, a mirror with two disks where one drive is starting to malfunction and cannot properly store the data any more.
 This is even worse when the data has not been accessed for a long time, as with long term archive storage.
 Traditional file systems need to run algorithms that check and repair the data like man:fsck[8].
 These commands take time, and in severe cases, an administrator has to manually decide which repair operation must be performed.
 When ZFS detects a data block with a checksum that does not match, it tries to read the data from the mirror disk.
 If that disk can provide the correct data, it will not only give that data to the application requesting it,
 but also correct the wrong data on the disk that had the bad checksum.
 This happens without any interaction from a system administrator during normal pool operation.
 
 The next example demonstrates this self-healing behavior.
 A mirrored pool of disks [.filename]#/dev/ada0# and [.filename]#/dev/ada1# is created.
 
 [source,shell]
 ....
 # zpool create healer mirror /dev/ada0 /dev/ada1
 # zpool status healer
   pool: healer
  state: ONLINE
   scan: none requested
 config:
 
     NAME        STATE     READ WRITE CKSUM
     healer      ONLINE       0     0     0
       mirror-0  ONLINE       0     0     0
        ada0     ONLINE       0     0     0
        ada1     ONLINE       0     0     0
 
 errors: No known data errors
 # zpool list
 NAME     SIZE  ALLOC   FREE   CKPOINT  EXPANDSZ   FRAG   CAP  DEDUP  HEALTH  ALTROOT
 healer   960M  92.5K   960M         -         -     0%    0%  1.00x  ONLINE  -
 ....
 
 Some important data that have to be protected from data errors using the self-healing feature are copied to the pool.
 A checksum of the pool is created for later comparison.
 
 [source,shell]
 ....
 # cp /some/important/data /healer
 # zfs list
 NAME     SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
 healer   960M  67.7M   892M     7%  1.00x  ONLINE  -
 # sha1 /healer > checksum.txt
 # cat checksum.txt
 SHA1 (/healer) = 2753eff56d77d9a536ece6694bf0a82740344d1f
 ....
 
 Data corruption is simulated by writing random data to the beginning of one of the disks in the mirror.
 To prevent ZFS from healing the data as soon as it is detected, the pool is exported before the corruption and imported again afterwards.
 
 [WARNING]
 ====
 This is a dangerous operation that can destroy vital data.
 It is shown here for demonstrational purposes only and should not be attempted during normal operation of a storage pool.
 Nor should this intentional corruption example be run on any disk with a different file system on it.
 Do not use any other disk device names other than the ones that are part of the pool.
 Make certain that proper backups of the pool are created before running the command!
 ====
 
 [source,shell]
 ....
 # zpool export healer
 # dd if=/dev/random of=/dev/ada1 bs=1m count=200
 200+0 records in
 200+0 records out
 209715200 bytes transferred in 62.992162 secs (3329227 bytes/sec)
 # zpool import healer
 ....
 
 The pool status shows that one device has experienced an error.
 Note that applications reading data from the pool did not receive any incorrect data.
 ZFS provided data from the [.filename]#ada0# device with the correct checksums.
 The device with the wrong checksum can be found easily as the `CKSUM` column contains a nonzero value.
 
 [source,shell]
 ....
 # zpool status healer
     pool: healer
    state: ONLINE
   status: One or more devices has experienced an unrecoverable error.  An
           attempt was made to correct the error.  Applications are unaffected.
   action: Determine if the device needs to be replaced, and clear the errors
           using 'zpool clear' or replace the device with 'zpool replace'.
      see: http://illumos.org/msg/ZFS-8000-4J
     scan: none requested
   config:
 
       NAME        STATE     READ WRITE CKSUM
       healer      ONLINE       0     0     0
         mirror-0  ONLINE       0     0     0
          ada0     ONLINE       0     0     0
          ada1     ONLINE       0     0     1
 
 errors: No known data errors
 ....
 
 The error was detected and handled by using the redundancy present in the unaffected [.filename]#ada0# mirror disk.
 A checksum comparison with the original one will reveal whether the pool is consistent again.
 
 [source,shell]
 ....
 # sha1 /healer >> checksum.txt
 # cat checksum.txt
 SHA1 (/healer) = 2753eff56d77d9a536ece6694bf0a82740344d1f
 SHA1 (/healer) = 2753eff56d77d9a536ece6694bf0a82740344d1f
 ....
 
 The two checksums that were generated before and after the intentional tampering with the pool data still match.
 This shows how ZFS is capable of detecting and correcting any errors automatically when the checksums differ.
 Note that this is only possible when there is enough redundancy present in the pool.
 A pool consisting of a single device has no self-healing capabilities.
 That is also the reason why checksums are so important in ZFS and should not be disabled for any reason.
 No man:fsck[8] or similar file system consistency check program is required to detect and correct this and the pool was still available during the time there was a problem.
 A scrub operation is now required to overwrite the corrupted data on [.filename]#ada1#.
 
 [source,shell]
 ....
 # zpool scrub healer
 # zpool status healer
   pool: healer
  state: ONLINE
 status: One or more devices has experienced an unrecoverable error.  An
             attempt was made to correct the error.  Applications are unaffected.
 action: Determine if the device needs to be replaced, and clear the errors
             using 'zpool clear' or replace the device with 'zpool replace'.
    see: http://illumos.org/msg/ZFS-8000-4J
   scan: scrub in progress since Mon Dec 10 12:23:30 2012
         10.4M scanned out of 67.0M at 267K/s, 0h3m to go
         9.63M repaired, 15.56% done
 config:
 
     NAME        STATE     READ WRITE CKSUM
     healer      ONLINE       0     0     0
       mirror-0  ONLINE       0     0     0
        ada0     ONLINE       0     0     0
        ada1     ONLINE       0     0   627  (repairing)
 
 errors: No known data errors
 ....
 
 The scrub operation reads data from [.filename]#ada0# and rewrites any data with an incorrect checksum on [.filename]#ada1#.
 This is indicated by the `(repairing)` output from `zpool status`.
 After the operation is complete, the pool status changes to:
 
 [source,shell]
 ....
 # zpool status healer
   pool: healer
  state: ONLINE
 status: One or more devices has experienced an unrecoverable error.  An
         attempt was made to correct the error.  Applications are unaffected.
 action: Determine if the device needs to be replaced, and clear the errors
              using 'zpool clear' or replace the device with 'zpool replace'.
    see: http://illumos.org/msg/ZFS-8000-4J
   scan: scrub repaired 66.5M in 0h2m with 0 errors on Mon Dec 10 12:26:25 2012
 config:
 
     NAME        STATE     READ WRITE CKSUM
     healer      ONLINE       0     0     0
       mirror-0  ONLINE       0     0     0
        ada0     ONLINE       0     0     0
        ada1     ONLINE       0     0 2.72K
 
 errors: No known data errors
 ....
 
 After the scrub operation completes and all the data has been synchronized from [.filename]#ada0# to [.filename]#ada1#,
 the error messages can be <<zfs-zpool-clear,cleared>> from the pool status by running `zpool clear`.
 
 [source,shell]
 ....
 # zpool clear healer
 # zpool status healer
   pool: healer
  state: ONLINE
   scan: scrub repaired 66.5M in 0h2m with 0 errors on Mon Dec 10 12:26:25 2012
 config:
 
     NAME        STATE     READ WRITE CKSUM
     healer      ONLINE       0     0     0
       mirror-0  ONLINE       0     0     0
        ada0     ONLINE       0     0     0
        ada1     ONLINE       0     0     0
 
 errors: No known data errors
 ....
 
 The pool is now back to a fully working state and all the errors have been cleared.
 
 [[zfs-zpool-online]]
 === Growing a Pool
 
 The usable size of a redundant pool is limited by the capacity of the smallest device in each vdev.
 The smallest device can be replaced with a larger device.
 After completing a <<zfs-zpool-replace,replace>> or <<zfs-term-resilver,resilver>> operation, the pool can grow to use the capacity of the new device. 
 For example, consider a mirror of a 1 TB drive and a 2 TB drive.
 The usable space is 1 TB.
 When the 1 TB drive is replaced with another 2 TB drive, the resilvering process copies the existing data onto the new drive.
 As both of the devices now have 2 TB capacity, the mirror's available space can be grown to 2 TB.
 
 Expansion is triggered by using `zpool online -e` on each device.
 After expansion of all devices, the additional space becomes available to the pool.
 
 [[zfs-zpool-import]]
 === Importing and Exporting Pools
 
 Pools are _exported_ before moving them to another system.
 All datasets are unmounted, and each device is marked as exported but still locked so it cannot be used by other disk subsystems.
 This allows pools to be _imported_ on other machines, other operating systems that support ZFS,
 and even different hardware architectures (with some caveats, see man:zpool[8]).
 When a dataset has open files, `zpool export -f` can be used to force the export of a pool.
 Use this with caution.
 The datasets are forcibly unmounted, potentially resulting in unexpected behavior by the applications which had open files on those datasets.
 
 Export a pool that is not in use:
 
 [source,shell]
 ....
 # zpool export mypool
 ....
 
 Importing a pool automatically mounts the datasets.
 This may not be the desired behavior, and can be prevented with `zpool import -N`.
 `zpool import -o` sets temporary properties for this import only.
 `zpool import altroot=` allows importing a pool with a base mount point instead of the root of the file system.
 If the pool was last used on a different system and was not properly exported, an import might have to be forced with `zpool import -f`.
 `zpool import -a` imports all pools that do not appear to be in use by another system.
 
 List all available pools for import:
 
 [source,shell]
 ....
 # zpool import
    pool: mypool
      id: 9930174748043525076
   state: ONLINE
  action: The pool can be imported using its name or numeric identifier.
  config:
 
         mypool      ONLINE
           ada2p3    ONLINE
 ....
 
 Import the pool with an alternative root directory:
 
 [source,shell]
 ....
 # zpool import -o altroot=/mnt mypool
 # zfs list
 zfs list
 NAME                 USED  AVAIL  REFER  MOUNTPOINT
 mypool               110K  47.0G    31K  /mnt/mypool
 ....
 
 [[zfs-zpool-upgrade]]
 === Upgrading a Storage Pool
 
 After upgrading FreeBSD, or if a pool has been imported from a system using an older version of ZFS,
 the pool can be manually upgraded to the latest version of ZFS to support newer features.
 Consider whether the pool may ever need to be imported on an older system before upgrading.
 Upgrading is a one-way process.
 Older pools can be upgraded, but pools with newer features cannot be downgraded.
 
 Upgrade a v28 pool to support `Feature Flags`:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
 status: The pool is formatted using a legacy on-disk format.  The pool can
         still be used, but some features are unavailable.
 action: Upgrade the pool using 'zpool upgrade'.  Once this is done, the
         pool will no longer be accessible on software that does not support feat
         flags.
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
 	    ada0    ONLINE       0     0     0
 	    ada1    ONLINE       0     0     0
 
 errors: No known data errors
 # zpool upgrade
 This system supports ZFS pool feature flags.
 
 The following pools are formatted with legacy version numbers and can
 be upgraded to use feature flags.  After being upgraded, these pools
 will no longer be accessible by software that does not support feature
 flags.
 
 VER  POOL
 ---  ------------
 28   mypool
 
 Use 'zpool upgrade -v' for a list of available legacy versions.
 Every feature flags pool has all supported features enabled.
 # zpool upgrade mypool
 This system supports ZFS pool feature flags.
 
 Successfully upgraded 'mypool' from version 28 to feature flags.
 Enabled the following features on 'mypool':
   async_destroy
   empty_bpobj
   lz4_compress
   multi_vdev_crash_dump
 ....
 
 The newer features of ZFS will not be available until `zpool upgrade` has completed.
 `zpool upgrade -v` can be used to see what new features will be provided by upgrading,
 as well as which features are already supported.
 
 Upgrade a pool to support additional feature flags:
 
 [source,shell]
 ....
 # zpool status
   pool: mypool
  state: ONLINE
 status: Some supported features are not enabled on the pool. The pool can
         still be used, but some features are unavailable.
 action: Enable all features using 'zpool upgrade'. Once this is done,
         the pool may no longer be accessible by software that does not support
         the features. See zpool-features(7) for details.
   scan: none requested
 config:
 
         NAME        STATE     READ WRITE CKSUM
         mypool      ONLINE       0     0     0
           mirror-0  ONLINE       0     0     0
 	    ada0    ONLINE       0     0     0
 	    ada1    ONLINE       0     0     0
 
 errors: No known data errors
 # zpool upgrade
 This system supports ZFS pool feature flags.
 
 All pools are formatted using feature flags.
 
 Some supported features are not enabled on the following pools. Once a
 feature is enabled the pool may become incompatible with software
 that does not support the feature. See zpool-features(7) for details.
 
 POOL  FEATURE
 ---------------
 zstore
       multi_vdev_crash_dump
       spacemap_histogram
       enabled_txg
       hole_birth
       extensible_dataset
       bookmarks
       filesystem_limits
 # zpool upgrade mypool
 This system supports ZFS pool feature flags.
 
 Enabled the following features on 'mypool':
   spacemap_histogram
   enabled_txg
   hole_birth
   extensible_dataset
   bookmarks
   filesystem_limits
 ....
 
 [WARNING]
 ====
 The boot code on systems that boot from a pool must be updated to support the new pool version.
 Use `gpart bootcode` on the partition that contains the boot code.
 There are two types of bootcode available, depending on way the system boots: GPT (the most common option) and EFI (for more modern systems).
 
 For legacy boot using GPT, use the following command:
 
 [source,shell]
 ....
 # gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada1
 ....
 
 For systems using EFI to boot, execute the following command:
 
 [source,shell]
 ....
 # gpart bootcode -p /boot/boot1.efifat -i 1 ada1
 ....
 
 Apply the bootcode to all bootable disks in the pool.
 See man:gpart[8] for more information.
 ====
 
 [[zfs-zpool-history]]
 === Displaying Recorded Pool History
 
 Commands that modify the pool are recorded.
 Recorded actions include the creation of datasets, changing properties, or replacement of a disk.
 This history is useful for reviewing how a pool was created and which user performed a specific action and when.
 History is not kept in a log file, but is part of the pool itself.
 The command to review this history is aptly named `zpool history`:
 
 [source,shell]
 ....
 # zpool history
 History for 'tank':
 2013-02-26.23:02:35 zpool create tank mirror /dev/ada0 /dev/ada1
 2013-02-27.18:50:58 zfs set atime=off tank
 2013-02-27.18:51:09 zfs set checksum=fletcher4 tank
 2013-02-27.18:51:18 zfs create tank/backup
 ....
 
 The output shows `zpool` and `zfs` commands that were executed on the pool along with a timestamp.
 Only commands that alter the pool in some way are recorded.
 Commands like `zfs list` are not included.
 When no pool name is specified, the history of all pools is displayed.
 
 `zpool history` can show even more information when the options `-i` or `-l` are provided.
 `-i` displays user-initiated events as well as internally logged ZFS events.
 
 [source,shell]
 ....
 # zpool history -i
 History for 'tank':
 2013-02-26.23:02:35 [internal pool create txg:5] pool spa 28; zfs spa 28; zpl 5;uts  9.1-RELEASE 901000 amd64
 2013-02-27.18:50:53 [internal property set txg:50] atime=0 dataset = 21
 2013-02-27.18:50:58 zfs set atime=off tank
 2013-02-27.18:51:04 [internal property set txg:53] checksum=7 dataset = 21
 2013-02-27.18:51:09 zfs set checksum=fletcher4 tank
 2013-02-27.18:51:13 [internal create txg:55] dataset = 39
 2013-02-27.18:51:18 zfs create tank/backup
 ....
 
 More details can be shown by adding `-l`.
 History records are shown in a long format, including information like the name of the user who issued the command and the hostname on which the change was made.
 
 [source,shell]
 ....
 # zpool history -l
 History for 'tank':
 2013-02-26.23:02:35 zpool create tank mirror /dev/ada0 /dev/ada1 [user 0 (root) on :global]
 2013-02-27.18:50:58 zfs set atime=off tank [user 0 (root) on myzfsbox:global]
 2013-02-27.18:51:09 zfs set checksum=fletcher4 tank [user 0 (root) on myzfsbox:global]
 2013-02-27.18:51:18 zfs create tank/backup [user 0 (root) on myzfsbox:global]
 ....
 
 The output shows that the `root` user created the mirrored pool with disks [.filename]#/dev/ada0# and [.filename]#/dev/ada1#.
 The hostname `myzfsbox` is also shown in the commands after the pool's creation.
 The hostname display becomes important when the pool is exported from one system and imported on another.
 The commands that are issued on the other system can clearly be distinguished by the hostname that is recorded for each command.
 
 Both options to `zpool history` can be combined to give the most detailed information possible for any given pool.
 Pool history provides valuable information when tracking down the actions that were performed or when more detailed output is needed for debugging.
 
 [[zfs-zpool-iostat]]
 === Performance Monitoring
 
 A built-in monitoring system can display pool I/O statistics in real time.
 It shows the amount of free and used space on the pool,
 how many read and write operations are being performed per second,
 and how much I/O bandwidth is currently being utilized.
 By default, all pools in the system are monitored and displayed.
 A pool name can be provided to limit monitoring to just that pool.
 A basic example:
 
 [source,shell]
 ....
 # zpool iostat
                capacity     operations    bandwidth
 pool        alloc   free   read  write   read  write
 ----------  -----  -----  -----  -----  -----  -----
 data         288G  1.53T      2     11  11.3K  57.1K
 ....
 
 To continuously monitor I/O activity, a number can be specified as the last parameter,
 indicating a interval in seconds to wait between updates.
 The next statistic line is printed after each interval.
 Press kbd:[Ctrl+C] to stop this continuous monitoring.
 Alternatively, give a second number on the command line after the interval to specify the total number of statistics to display.
 
 Even more detailed I/O statistics can be displayed with `-v`.
 Each device in the pool is shown with a statistics line.
 This is useful in seeing how many read and write operations are being performed on each device,
 and can help determine if any individual device is slowing down the pool.
 This example shows a mirrored pool with two devices:
 
 [source,shell]
 ....
 # zpool iostat -v 
                             capacity     operations    bandwidth
 pool                     alloc   free   read  write   read  write
 -----------------------  -----  -----  -----  -----  -----  -----
 data                      288G  1.53T      2     12  9.23K  61.5K
   mirror                  288G  1.53T      2     12  9.23K  61.5K
     ada1                     -      -      0      4  5.61K  61.7K
     ada2                     -      -      1      4  5.04K  61.7K
 -----------------------  -----  -----  -----  -----  -----  -----
 ....
 
 [[zfs-zpool-split]]
 === Splitting a Storage Pool
 
 A pool consisting of one or more mirror vdevs can be split into two pools.
 Unless otherwise specified, the last member of each mirror is detached and used to create a new pool containing the same data.
 The operation should first be attempted with `-n`.
 The details of the proposed operation are displayed without it actually being performed.
 This helps confirm that the operation will do what the user intends.
 
 [[zfs-zfs]]
 == `zfs` Administration
 
 The `zfs` utility is responsible for creating, destroying, and managing all ZFS datasets that exist within a pool.
 The pool is managed using <<zfs-zpool,`zpool`>>.
 
 [[zfs-zfs-create]]
 === Creating and Destroying Datasets
 
 Unlike traditional disks and volume managers, space in ZFS is _not_ preallocated.
 With traditional file systems, after all of the space is partitioned and assigned, there is no way to add an additional file system without adding a new disk. 
 With ZFS, new file systems can be created at any time.
 Each <<zfs-term-dataset,_dataset_>> has properties including features like compression, deduplication, caching, and quotas, as well as other useful properties like readonly, case sensitivity, network file sharing, and a mount point.
 Datasets can be nested inside each other, and child datasets will inherit properties from their parents.
 Each dataset can be administered, <<zfs-zfs-allow,delegated>>, <<zfs-zfs-send,replicated>>, <<zfs-zfs-snapshot,snapshotted>>, <<zfs-zfs-jail,jailed>>, and destroyed as a unit.
 There are many advantages to creating a separate dataset for each different type or set of files.
 The only drawbacks to having an extremely large number of datasets is that some commands like `zfs list` will be slower,
 and the mounting of hundreds or even thousands of datasets can slow the FreeBSD boot process.
 
 Create a new dataset and enable <<zfs-term-compression-lz4,LZ4 compression>> on it:
 
 [source,shell]
 ....
 # zfs list
 NAME                  USED  AVAIL  REFER  MOUNTPOINT
 mypool                781M  93.2G   144K  none
 mypool/ROOT           777M  93.2G   144K  none
 mypool/ROOT/default   777M  93.2G   777M  /
 mypool/tmp            176K  93.2G   176K  /tmp
 mypool/usr            616K  93.2G   144K  /usr
 mypool/usr/home       184K  93.2G   184K  /usr/home
 mypool/usr/ports      144K  93.2G   144K  /usr/ports
 mypool/usr/src        144K  93.2G   144K  /usr/src
 mypool/var           1.20M  93.2G   608K  /var
 mypool/var/crash      148K  93.2G   148K  /var/crash
 mypool/var/log        178K  93.2G   178K  /var/log
 mypool/var/mail       144K  93.2G   144K  /var/mail
 mypool/var/tmp        152K  93.2G   152K  /var/tmp
 # zfs create -o compress=lz4 mypool/usr/mydataset
 # zfs list
 NAME                   USED  AVAIL  REFER  MOUNTPOINT
 mypool                 781M  93.2G   144K  none
 mypool/ROOT            777M  93.2G   144K  none
 mypool/ROOT/default    777M  93.2G   777M  /
 mypool/tmp             176K  93.2G   176K  /tmp
 mypool/usr             704K  93.2G   144K  /usr
 mypool/usr/home        184K  93.2G   184K  /usr/home
 mypool/usr/mydataset  87.5K  93.2G  87.5K  /usr/mydataset
 mypool/usr/ports       144K  93.2G   144K  /usr/ports
 mypool/usr/src         144K  93.2G   144K  /usr/src
 mypool/var            1.20M  93.2G   610K  /var
 mypool/var/crash       148K  93.2G   148K  /var/crash
 mypool/var/log         178K  93.2G   178K  /var/log
 mypool/var/mail        144K  93.2G   144K  /var/mail
 mypool/var/tmp         152K  93.2G   152K  /var/tmp
 ....
 
 Destroying a dataset is much quicker than deleting all of the files that reside on the dataset,
 as it does not involve scanning all of the files and updating all of the corresponding metadata.
 
 Destroy the previously-created dataset:
 
 [source,shell]
 ....
 # zfs list
 NAME                   USED  AVAIL  REFER  MOUNTPOINT
 mypool                 880M  93.1G   144K  none
 mypool/ROOT            777M  93.1G   144K  none
 mypool/ROOT/default    777M  93.1G   777M  /
 mypool/tmp             176K  93.1G   176K  /tmp
 mypool/usr             101M  93.1G   144K  /usr
 mypool/usr/home        184K  93.1G   184K  /usr/home
 mypool/usr/mydataset   100M  93.1G   100M  /usr/mydataset
 mypool/usr/ports       144K  93.1G   144K  /usr/ports
 mypool/usr/src         144K  93.1G   144K  /usr/src
 mypool/var            1.20M  93.1G   610K  /var
 mypool/var/crash       148K  93.1G   148K  /var/crash
 mypool/var/log         178K  93.1G   178K  /var/log
 mypool/var/mail        144K  93.1G   144K  /var/mail
 mypool/var/tmp         152K  93.1G   152K  /var/tmp
 # zfs destroy mypool/usr/mydataset
 # zfs list
 NAME                  USED  AVAIL  REFER  MOUNTPOINT
 mypool                781M  93.2G   144K  none
 mypool/ROOT           777M  93.2G   144K  none
 mypool/ROOT/default   777M  93.2G   777M  /
 mypool/tmp            176K  93.2G   176K  /tmp
 mypool/usr            616K  93.2G   144K  /usr
 mypool/usr/home       184K  93.2G   184K  /usr/home
 mypool/usr/ports      144K  93.2G   144K  /usr/ports
 mypool/usr/src        144K  93.2G   144K  /usr/src
 mypool/var           1.21M  93.2G   612K  /var
 mypool/var/crash      148K  93.2G   148K  /var/crash
 mypool/var/log        178K  93.2G   178K  /var/log
 mypool/var/mail       144K  93.2G   144K  /var/mail
 mypool/var/tmp        152K  93.2G   152K  /var/tmp
 ....
 
 In modern versions of ZFS, `zfs destroy` is asynchronous, and the free space might take several minutes to appear in the pool.
 Use `zpool get freeing _poolname_` to see the `freeing` property, indicating how many datasets are having their blocks freed in the background.
 If there are child datasets, like <<zfs-term-snapshot,snapshots>> or other datasets, then the parent cannot be destroyed.
 To destroy a dataset and all of its children, use `-r` to recursively destroy the dataset and all of its children.
 Use `-n -v` to list datasets and snapshots that would be destroyed by this operation, but do not actually destroy anything.
 Space that would be reclaimed by destruction of snapshots is also shown.
 
 [[zfs-zfs-volume]]
 === Creating and Destroying Volumes
 
 A volume is a special type of dataset.
 Rather than being mounted as a file system, it is exposed as a block device under [.filename]#/dev/zvol/poolname/dataset#.
 This allows the volume to be used for other file systems, to back the disks of a virtual machine, or to be exported using protocols like iSCSI or HAST.
 
 A volume can be formatted with any file system, or used without a file system to store raw data.
 To the user, a volume appears to be a regular disk. Putting ordinary file systems on these _zvols_ provides features that ordinary disks or file systems do not normally have.
 For example, using the compression property on a 250 MB volume allows creation of a compressed FAT file system.
 
 [source,shell]
 ....
 # zfs create -V 250m -o compression=on tank/fat32
 # zfs list tank
 NAME USED AVAIL REFER MOUNTPOINT
 tank 258M  670M   31K /tank
 # newfs_msdos -F32 /dev/zvol/tank/fat32
 # mount -t msdosfs /dev/zvol/tank/fat32 /mnt
 # df -h /mnt | grep fat32
 Filesystem           Size Used Avail Capacity Mounted on
 /dev/zvol/tank/fat32 249M  24k  249M     0%   /mnt
 # mount | grep fat32
 /dev/zvol/tank/fat32 on /mnt (msdosfs, local)
 ....
 
 Destroying a volume is much the same as destroying a regular file system dataset.
 The operation is nearly instantaneous, but it may take several minutes for the free space to be reclaimed in the background.
 
 [[zfs-zfs-rename]]
 === Renaming a Dataset
 
 The name of a dataset can be changed with `zfs rename`.
 The parent of a dataset can also be changed with this command.
 Renaming a dataset to be under a different parent dataset will change the value of those properties that are inherited from the parent dataset.
 When a dataset is renamed, it is unmounted and then remounted in the new location (which is inherited from the new parent dataset).
 This behavior can be prevented with `-u`.
 
 Rename a dataset and move it to be under a different parent dataset:
 
 [source,shell]
 ....
 # zfs list
 NAME                   USED  AVAIL  REFER  MOUNTPOINT
 mypool                 780M  93.2G   144K  none
 mypool/ROOT            777M  93.2G   144K  none
 mypool/ROOT/default    777M  93.2G   777M  /
 mypool/tmp             176K  93.2G   176K  /tmp
 mypool/usr             704K  93.2G   144K  /usr
 mypool/usr/home        184K  93.2G   184K  /usr/home
 mypool/usr/mydataset  87.5K  93.2G  87.5K  /usr/mydataset
 mypool/usr/ports       144K  93.2G   144K  /usr/ports
 mypool/usr/src         144K  93.2G   144K  /usr/src
 mypool/var            1.21M  93.2G   614K  /var
 mypool/var/crash       148K  93.2G   148K  /var/crash
 mypool/var/log         178K  93.2G   178K  /var/log
 mypool/var/mail        144K  93.2G   144K  /var/mail
 mypool/var/tmp         152K  93.2G   152K  /var/tmp
 # zfs rename mypool/usr/mydataset mypool/var/newname
 # zfs list
 NAME                  USED  AVAIL  REFER  MOUNTPOINT
 mypool                780M  93.2G   144K  none
 mypool/ROOT           777M  93.2G   144K  none
 mypool/ROOT/default   777M  93.2G   777M  /
 mypool/tmp            176K  93.2G   176K  /tmp
 mypool/usr            616K  93.2G   144K  /usr
 mypool/usr/home       184K  93.2G   184K  /usr/home
 mypool/usr/ports      144K  93.2G   144K  /usr/ports
 mypool/usr/src        144K  93.2G   144K  /usr/src
 mypool/var           1.29M  93.2G   614K  /var
 mypool/var/crash      148K  93.2G   148K  /var/crash
 mypool/var/log        178K  93.2G   178K  /var/log
 mypool/var/mail       144K  93.2G   144K  /var/mail
 mypool/var/newname   87.5K  93.2G  87.5K  /var/newname
 mypool/var/tmp        152K  93.2G   152K  /var/tmp
 ....
 
 Snapshots can also be renamed like this.
 Due to the nature of snapshots, they cannot be renamed into a different parent dataset.
 To rename a recursive snapshot, specify `-r`, and all snapshots with the same name in child datasets will also be renamed.
 
 [source,shell]
 ....
 # zfs list -t snapshot
 NAME                                USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/newname@first_snapshot      0      -  87.5K  -
 # zfs rename mypool/var/newname@first_snapshot new_snapshot_name
 # zfs list -t snapshot
 NAME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/newname@new_snapshot_name      0      -  87.5K  -
 ....
 
 [[zfs-zfs-set]]
 === Setting Dataset Properties
 
 Each ZFS dataset has a number of properties that control its behavior.
 Most properties are automatically inherited from the parent dataset, but can be overridden locally.
 Set a property on a dataset with `zfs set _property=value dataset_`.
 Most properties have a limited set of valid values, `zfs get` will display each possible property and valid values.
 Most properties can be reverted to their inherited values using `zfs inherit`.
 
 User-defined properties can also be set.
 They become part of the dataset configuration and can be used to provide additional information about the dataset or its contents.
 To distinguish these custom properties from the ones supplied as part of ZFS, a colon (`:`) is used to create a custom namespace for the property.
 
 [source,shell]
 ....
 # zfs set custom:costcenter=1234 tank
 # zfs get custom:costcenter tank
 NAME PROPERTY           VALUE SOURCE
 tank custom:costcenter  1234  local
 ....
 
 To remove a custom property, use `zfs inherit` with `-r`.
 If the custom property is not defined in any of the parent datasets,
 it will be removed completely (although the changes are still recorded in the pool's history).
 
 [source,shell]
 ....
 # zfs inherit -r custom:costcenter tank
 # zfs get custom:costcenter tank
 NAME    PROPERTY           VALUE              SOURCE
 tank    custom:costcenter  -                  -
 # zfs get all tank | grep custom:costcenter
 #
 ....
 
 [[zfs-zfs-set-share]]
 ==== Getting and Setting Share Properties
 
 Two commonly used and useful dataset properties are the NFS and SMB share options.
 Setting these define if and how ZFS datasets may be shared on the network.
 At present, only setting sharing via NFS is supported on FreeBSD.
 To get the current status of a share, enter:
 
 [source,shell]
 ....
 # zfs get sharenfs mypool/usr/home
 NAME             PROPERTY  VALUE    SOURCE
 mypool/usr/home  sharenfs  on       local
 # zfs get sharesmb mypool/usr/home
 NAME             PROPERTY  VALUE    SOURCE
 mypool/usr/home  sharesmb  off      local
 ....
 
 To enable sharing of a dataset, enter:
 
 [source,shell]
 ....
 #  zfs set sharenfs=on mypool/usr/home
 ....
 
 It is also possible to set additional options for sharing datasets through NFS, such as `-alldirs`, `-maproot` and `-network`.
 To set additional options to a dataset shared through NFS, enter:
 
 [source,shell]
 ....
 #  zfs set sharenfs="-alldirs,-maproot=root,-network=192.168.1.0/24" mypool/usr/home
 ....
 
 [[zfs-zfs-snapshot]]
 === Managing Snapshots
 
 <<zfs-term-snapshot,Snapshots>> are one of the most powerful features of ZFS.
 A snapshot provides a read-only, point-in-time copy of the dataset.
 With Copy-On-Write (COW), snapshots can be created quickly by preserving the older version of the data on disk.
 If no snapshots exist, space is reclaimed for future use when data is rewritten or deleted.
 Snapshots preserve disk space by recording only the differences between the current dataset and a previous version.
 Snapshots are allowed only on whole datasets, not on individual files or directories.
 When a snapshot is created from a dataset, everything contained in it is duplicated.
 This includes the file system properties, files, directories, permissions, and so on.
 Snapshots use no additional space when they are first created, only consuming space as the blocks they reference are changed.
 Recursive snapshots taken with `-r` create a snapshot with the same name on the dataset and all of its children, providing a consistent moment-in-time snapshot of all of the file systems.
 This can be important when an application has files on multiple datasets that are related or dependent upon each other.
 Without snapshots, a backup would have copies of the files from different points in time.
 
 Snapshots in ZFS provide a variety of features that even other file systems with snapshot functionality lack.
 A typical example of snapshot use is to have a quick way of backing up the current state of the file system when a risky action like a software installation or a system upgrade is performed.
 If the action fails, the snapshot can be rolled back and the system has the same state as when the snapshot was created.
 If the upgrade was successful, the snapshot can be deleted to free up space.
 Without snapshots, a failed upgrade often requires a restore from backup, which is tedious, time consuming, and may require downtime during which the system cannot be used.
 Snapshots can be rolled back quickly, even while the system is running in normal operation, with little or no downtime.
 The time savings are enormous with multi-terabyte storage systems and the time required to copy the data from backup.
 Snapshots are not a replacement for a complete backup of a pool, but can be used as a quick and easy way to store a copy of the dataset at a specific point in time.
 
 [[zfs-zfs-snapshot-creation]]
 ==== Creating Snapshots
 
 Snapshots are created with `zfs snapshot _dataset_@_snapshotname_`.
 Adding `-r` creates a snapshot recursively, with the same name on all child datasets.
 
 Create a recursive snapshot of the entire pool:
 
 [source,shell]
 ....
 # zfs list -t all
 NAME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool                                 780M  93.2G   144K  none
 mypool/ROOT                            777M  93.2G   144K  none
 mypool/ROOT/default                    777M  93.2G   777M  /
 mypool/tmp                             176K  93.2G   176K  /tmp
 mypool/usr                             616K  93.2G   144K  /usr
 mypool/usr/home                        184K  93.2G   184K  /usr/home
 mypool/usr/ports                       144K  93.2G   144K  /usr/ports
 mypool/usr/src                         144K  93.2G   144K  /usr/src
 mypool/var                            1.29M  93.2G   616K  /var
 mypool/var/crash                       148K  93.2G   148K  /var/crash
 mypool/var/log                         178K  93.2G   178K  /var/log
 mypool/var/mail                        144K  93.2G   144K  /var/mail
 mypool/var/newname                    87.5K  93.2G  87.5K  /var/newname
 mypool/var/newname@new_snapshot_name      0      -  87.5K  -
 mypool/var/tmp                         152K  93.2G   152K  /var/tmp
 # zfs snapshot -r mypool@my_recursive_snapshot
 # zfs list -t snapshot
 NAME                                        USED  AVAIL  REFER  MOUNTPOINT
 mypool@my_recursive_snapshot                   0      -   144K  -
 mypool/ROOT@my_recursive_snapshot              0      -   144K  -
 mypool/ROOT/default@my_recursive_snapshot      0      -   777M  -
 mypool/tmp@my_recursive_snapshot               0      -   176K  -
 mypool/usr@my_recursive_snapshot               0      -   144K  -
 mypool/usr/home@my_recursive_snapshot          0      -   184K  -
 mypool/usr/ports@my_recursive_snapshot         0      -   144K  -
 mypool/usr/src@my_recursive_snapshot           0      -   144K  -
 mypool/var@my_recursive_snapshot               0      -   616K  -
 mypool/var/crash@my_recursive_snapshot         0      -   148K  -
 mypool/var/log@my_recursive_snapshot           0      -   178K  -
 mypool/var/mail@my_recursive_snapshot          0      -   144K  -
 mypool/var/newname@new_snapshot_name           0      -  87.5K  -
 mypool/var/newname@my_recursive_snapshot       0      -  87.5K  -
 mypool/var/tmp@my_recursive_snapshot           0      -   152K  -
 ....
 
 Snapshots are not shown by a normal `zfs list` operation.
 To list snapshots, `-t snapshot` is appended to `zfs list`.
 `-t all` displays both file systems and snapshots.
 
 Snapshots are not mounted directly, so no path is shown in the `MOUNTPOINT` column.
 There is no mention of available disk space in the `AVAIL` column, as snapshots cannot be written to after they are created.
 Compare the snapshot to the original dataset from which it was created:
 
 [source,shell]
 ....
 # zfs list -rt all mypool/usr/home
 NAME                                    USED  AVAIL  REFER  MOUNTPOINT
 mypool/usr/home                         184K  93.2G   184K  /usr/home
 mypool/usr/home@my_recursive_snapshot      0      -   184K  -
 ....
 
 Displaying both the dataset and the snapshot together reveals how snapshots work in <<zfs-term-cow,COW>> fashion.
 They save only the changes (_delta_) that were made and not the complete file system contents all over again.
 This means that snapshots take little space when few changes are made.
 Space usage can be made even more apparent by copying a file to the dataset, then making a second snapshot:
 
 [source,shell]
 ....
 # cp /etc/passwd /var/tmp
 # zfs snapshot mypool/var/tmp@after_cp
 # zfs list -rt all mypool/var/tmp
 NAME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/tmp                         206K  93.2G   118K  /var/tmp
 mypool/var/tmp@my_recursive_snapshot    88K      -   152K  -
 mypool/var/tmp@after_cp                   0      -   118K  -
 ....
 
 The second snapshot contains only the changes to the dataset after the copy operation.
 This yields enormous space savings.
 Notice that the size of the snapshot `_mypool/var/tmp@my_recursive_snapshot_` also changed in the `USED` column to indicate the changes between itself and the snapshot taken afterwards.
 
 [[zfs-zfs-snapshot-diff]]
 ==== Comparing Snapshots
 
 ZFS provides a built-in command to compare the differences in content between two snapshots.
 This is helpful when many snapshots were taken over time and the user wants to see how the file system has changed over time.
 For example, `zfs diff` lets a user find the latest snapshot that still contains a file that was accidentally deleted.
 Doing this for the two snapshots that were created in the previous section yields this output:
 
 [source,shell]
 ....
 # zfs list -rt all mypool/var/tmp
 NAME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/tmp                         206K  93.2G   118K  /var/tmp
 mypool/var/tmp@my_recursive_snapshot    88K      -   152K  -
 mypool/var/tmp@after_cp                   0      -   118K  -
 # zfs diff mypool/var/tmp@my_recursive_snapshot
 M       /var/tmp/
 +       /var/tmp/passwd
 ....
 
 The command lists the changes between the specified snapshot (in this case `_mypool/var/tmp@my_recursive_snapshot_`) and the live file system.
 The first column shows the type of change:
 
 [.informaltable]
 [cols="20%,80%"]
 |===
 
 |+
 |The path or file was added.
 
 |-
 |The path or file was deleted.
 
 |M
 |The path or file was modified.
 
 |R
 |The path or file was renamed.
 |===
 
 Comparing the output with the table, it becomes clear that [.filename]#passwd# was added after the snapshot `_mypool/var/tmp@my_recursive_snapshot_` was created. This also resulted in a modification to the parent directory mounted at `_/var/tmp_`.
 
 Comparing two snapshots is helpful when using the ZFS replication feature to transfer a dataset to a different host for backup purposes.
 
 Compare two snapshots by providing the full dataset name and snapshot name of both datasets:
 
 [source,shell]
 ....
 # cp /var/tmp/passwd /var/tmp/passwd.copy
 # zfs snapshot mypool/var/tmp@diff_snapshot
 # zfs diff mypool/var/tmp@my_recursive_snapshot mypool/var/tmp@diff_snapshot
 M       /var/tmp/
 +       /var/tmp/passwd
 +       /var/tmp/passwd.copy
 # zfs diff mypool/var/tmp@my_recursive_snapshot mypool/var/tmp@after_cp
 M       /var/tmp/
 +       /var/tmp/passwd
 ....
 
 A backup administrator can compare two snapshots received from the sending host and determine the actual changes in the dataset.
 See the <<zfs-zfs-send,Replication>> section for more information.
 
 [[zfs-zfs-snapshot-rollback]]
 ==== Snapshot Rollback
 
 When at least one snapshot is available, it can be rolled back to at any time.
 Most of the time this is the case when the current state of the dataset is no longer required and an older version is preferred.
 Scenarios such as local development tests have gone wrong, botched system updates hampering the system's overall functionality,
 or the requirement to restore accidentally deleted files or directories are all too common occurrences.
 Luckily, rolling back a snapshot is just as easy as typing `zfs rollback _snapshotname_`.
 Depending on how many changes are involved, the operation will finish in a certain amount of time.
 During that time, the dataset always remains in a consistent state, much like a database that conforms to ACID principles is performing a rollback.
 This is happening while the dataset is live and accessible without requiring a downtime.
 Once the snapshot has been rolled back, the dataset has the same state as it had when the snapshot was originally taken.
 All other data in that dataset that was not part of the snapshot is discarded.
 Taking a snapshot of the current state of the dataset before rolling back to a previous one is a good idea when some data is required later.
 This way, the user can roll back and forth between snapshots without losing data that is still valuable.
 
 In the first example, a snapshot is rolled back because of a careless `rm` operation that removes too much data than was intended.
 
 [source,shell]
 ....
 # zfs list -rt all mypool/var/tmp
 NAME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/tmp                         262K  93.2G   120K  /var/tmp
 mypool/var/tmp@my_recursive_snapshot    88K      -   152K  -
 mypool/var/tmp@after_cp               53.5K      -   118K  -
 mypool/var/tmp@diff_snapshot              0      -   120K  -
 # ls /var/tmp
 passwd          passwd.copy     vi.recover
 # rm /var/tmp/passwd*
 # ls /var/tmp
 vi.recover
 ....
 
 At this point, the user realized that too many files were deleted and wants them back.
 ZFS provides an easy way to get them back using rollbacks, but only when snapshots of important data are performed on a regular basis.
 To get the files back and start over from the last snapshot, issue the command:
 
 [source,shell]
 ....
 # zfs rollback mypool/var/tmp@diff_snapshot
 # ls /var/tmp
 passwd          passwd.copy     vi.recover
 ....
 
 The rollback operation restored the dataset to the state of the last snapshot.
 It is also possible to roll back to a snapshot that was taken much earlier and has other snapshots that were created after it.
 When trying to do this, ZFS will issue this warning:
 
 [source,shell]
 ....
 # zfs list -rt snapshot mypool/var/tmp
 AME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/tmp@my_recursive_snapshot    88K      -   152K  -
 mypool/var/tmp@after_cp               53.5K      -   118K  -
 mypool/var/tmp@diff_snapshot              0      -   120K  -
 # zfs rollback mypool/var/tmp@my_recursive_snapshot
 cannot rollback to 'mypool/var/tmp@my_recursive_snapshot': more recent snapshots exist
 use '-r' to force deletion of the following snapshots:
 mypool/var/tmp@after_cp
 mypool/var/tmp@diff_snapshot
 ....
 
 This warning means that snapshots exist between the current state of the dataset and the snapshot to which the user wants to roll back.
 To complete the rollback, these snapshots must be deleted.
 ZFS cannot track all the changes between different states of the dataset, because snapshots are read-only.
 ZFS will not delete the affected snapshots unless the user specifies `-r` to indicate that this is the desired action.
 If that is the intention, and the consequences of losing all intermediate snapshots is understood, the command can be issued:
 
 [source,shell]
 ....
 # zfs rollback -r mypool/var/tmp@my_recursive_snapshot
 # zfs list -rt snapshot mypool/var/tmp
 NAME                                   USED  AVAIL  REFER  MOUNTPOINT
 mypool/var/tmp@my_recursive_snapshot     8K      -   152K  -
 # ls /var/tmp
 vi.recover
 ....
 
 The output from `zfs list -t snapshot` confirms that the intermediate snapshots were removed as a result of `zfs rollback -r`.
 
 [[zfs-zfs-snapshot-snapdir]]
 ==== Restoring Individual Files from Snapshots
 
 Snapshots are mounted in a hidden directory under the parent dataset: [.filename]#.zfs/snapshots/snapshotname#.
 By default, these directories will not be displayed even when a standard `ls -a` is issued.
 Although the directory is not displayed, it is there nevertheless and can be accessed like any normal directory.
 The property named `snapdir` controls whether these hidden directories show up in a directory listing.
 Setting the property to `visible` allows them to appear in the output of `ls` and other commands that deal with directory contents.
 
 [source,shell]
 ....
 # zfs get snapdir mypool/var/tmp
 NAME            PROPERTY  VALUE    SOURCE
 mypool/var/tmp  snapdir   hidden   default
 # ls -a /var/tmp
 .               ..              passwd          vi.recover
 # zfs set snapdir=visible mypool/var/tmp
 # ls -a /var/tmp
 .               ..              .zfs            passwd          vi.recover
 ....
 
 Individual files can easily be restored to a previous state by copying them from the snapshot back to the parent dataset.
 The directory structure below [.filename]#.zfs/snapshot# has a directory named exactly like the snapshots taken earlier to make it easier to identify them.
 In the next example, it is assumed that a file is to be restored from the hidden [.filename]#.zfs# directory by copying it from the snapshot that contained the latest version of the file:
 
 [source,shell]
 ....
 # rm /var/tmp/passwd
 # ls -a /var/tmp
 .               ..              .zfs            vi.recover
 # ls /var/tmp/.zfs/snapshot
 after_cp                my_recursive_snapshot
 # ls /var/tmp/.zfs/snapshot/after_cp
 passwd          vi.recover
 # cp /var/tmp/.zfs/snapshot/after_cp/passwd /var/tmp
 ....
 
 When `ls .zfs/snapshot` was issued, the `snapdir` property might have been set to hidden, but it would still be possible to list the contents of that directory.
 It is up to the administrator to decide whether these directories will be displayed.
 It is possible to display these for certain datasets and prevent it for others.
 Copying files or directories from this hidden [.filename]#.zfs/snapshot# is simple enough.
 Trying it the other way around results in this error:
 
 [source,shell]
 ....
 # cp /etc/rc.conf /var/tmp/.zfs/snapshot/after_cp/
 cp: /var/tmp/.zfs/snapshot/after_cp/rc.conf: Read-only file system
 ....
 
 The error reminds the user that snapshots are read-only and cannot be changed after creation.
 Files cannot be copied into or removed from snapshot directories because that would change the state of the dataset they represent.
 
 Snapshots consume space based on how much the parent file system has changed since the time of the snapshot.
 The `written` property of a snapshot tracks how much space is being used by the snapshot.
 
 Snapshots are destroyed and the space reclaimed with `zfs destroy _dataset_@_snapshot_`.
 Adding `-r` recursively removes all snapshots with the same name under the parent dataset.
 Adding `-n -v` to the command displays a list of the snapshots that would be deleted and an estimate of how much space would be reclaimed without performing the actual destroy operation.
 
 [[zfs-zfs-clones]]
 === Managing Clones
 
 A clone is a copy of a snapshot that is treated more like a regular dataset.
 Unlike a snapshot, a clone is not read only, is mounted, and can have its own properties.
 Once a clone has been created using `zfs clone`, the snapshot it was created from cannot be destroyed.
 The child/parent relationship between the clone and the snapshot can be reversed using `zfs promote`.
 After a clone has been promoted, the snapshot becomes a child of the clone, rather than of the original parent dataset.
 This will change how the space is accounted, but not actually change the amount of space consumed.
 The clone can be mounted at any point within the ZFS file system hierarchy, not just below the original location of the snapshot.
 
 To demonstrate the clone feature, this example dataset is used:
 
 [source,shell]
 ....
 # zfs list -rt all camino/home/joe
 NAME                    USED  AVAIL  REFER  MOUNTPOINT
 camino/home/joe         108K   1.3G    87K  /usr/home/joe
 camino/home/joe@plans    21K      -  85.5K  -
 camino/home/joe@backup    0K      -    87K  -
 ....
 
 A typical use for clones is to experiment with a specific dataset while keeping the snapshot around to fall back to in case something goes wrong.
 Since snapshots cannot be changed, a read/write clone of a snapshot is created.
 After the desired result is achieved in the clone, the clone can be promoted to a dataset and the old file system removed.
 This is not strictly necessary, as the clone and dataset can coexist without problems.
 
 [source,shell]
 ....
 # zfs clone camino/home/joe@backup camino/home/joenew
 # ls /usr/home/joe*
 /usr/home/joe:
 backup.txz     plans.txt
 
 /usr/home/joenew:
 backup.txz     plans.txt
 # df -h /usr/home
 Filesystem          Size    Used   Avail Capacity  Mounted on
 usr/home/joe        1.3G     31k    1.3G     0%    /usr/home/joe
 usr/home/joenew     1.3G     31k    1.3G     0%    /usr/home/joenew
 ....
 
 After a clone is created it is an exact copy of the state the dataset was in when the snapshot was taken.
 The clone can now be changed independently from its originating dataset.
 The only connection between the two is the snapshot.
 ZFS records this connection in the property `origin`.
 Once the dependency between the snapshot and the clone has been removed by promoting the clone using `zfs promote`, the `origin` of the clone is removed as it is now an independent dataset.
 This example demonstrates it:
 
 [source,shell]
 ....
 # zfs get origin camino/home/joenew
 NAME                  PROPERTY  VALUE                     SOURCE
 camino/home/joenew    origin    camino/home/joe@backup    -
 # zfs promote camino/home/joenew
 # zfs get origin camino/home/joenew
 NAME                  PROPERTY  VALUE   SOURCE
 camino/home/joenew    origin    -       -
 ....
 
 After making some changes like copying [.filename]#loader.conf# to the promoted clone, for example, the old directory becomes obsolete in this case.
 Instead, the promoted clone can replace it.
 This can be achieved by two consecutive commands: `zfs destroy` on the old dataset and `zfs rename` on the clone to name it like the old dataset (it could also get an entirely different name).
 
 [source,shell]
 ....
 # cp /boot/defaults/loader.conf /usr/home/joenew
 # zfs destroy -f camino/home/joe
 # zfs rename camino/home/joenew camino/home/joe
 # ls /usr/home/joe
 backup.txz     loader.conf     plans.txt
 # df -h /usr/home
 Filesystem          Size    Used   Avail Capacity  Mounted on
 usr/home/joe        1.3G    128k    1.3G     0%    /usr/home/joe
 ....
 
 The cloned snapshot is now handled like an ordinary dataset.
 It contains all the data from the original snapshot plus the files that were added to it like [.filename]#loader.conf#.
 Clones can be used in different scenarios to provide useful features to ZFS users.
 For example, jails could be provided as snapshots containing different sets of installed applications.
 Users can clone these snapshots and add their own applications as they see fit.
 Once they are satisfied with the changes, the clones can be promoted to full datasets and provided to end users to work with like they would with a real dataset.
 This saves time and administrative overhead when providing these jails.
 
 [[zfs-zfs-send]]
 === Replication
 
 Keeping data on a single pool in one location exposes it to risks like theft and natural or human disasters.
 Making regular backups of the entire pool is vital.
 ZFS provides a built-in serialization feature that can send a stream representation of the data to standard output.
 Using this technique, it is possible to not only store the data on another pool connected to the local system, but also to send it over a network to another system.
 Snapshots are the basis for this replication (see the section on <<zfs-zfs-snapshot,ZFS snapshots>>).
 The commands used for replicating data are `zfs send` and `zfs receive`.
 
 These examples demonstrate ZFS replication with these two pools:
 
 [source,shell]
 ....
 # zpool list
 NAME    SIZE  ALLOC   FREE   CKPOINT  EXPANDSZ   FRAG   CAP  DEDUP  HEALTH  ALTROOT
 backup  960M    77K   896M         -         -     0%    0%  1.00x  ONLINE  -
 mypool  984M  43.7M   940M         -         -     0%    4%  1.00x  ONLINE  -
 ....
 
 The pool named _mypool_ is the primary pool where data is written to and read from on a regular basis.
 A second pool, _backup_ is used as a standby in case the primary pool becomes unavailable.
 Note that this fail-over is not done automatically by ZFS, but must be manually done by a system administrator when needed.
 A snapshot is used to provide a consistent version of the file system to be replicated.
 Once a snapshot of _mypool_ has been created, it can be copied to the _backup_ pool.
 Only snapshots can be replicated.
 Changes made since the most recent snapshot will not be included.
 
 [source,shell]
 ....
 # zfs snapshot mypool@backup1
 # zfs list -t snapshot
 NAME                    USED  AVAIL  REFER  MOUNTPOINT
 mypool@backup1             0      -  43.6M  -
 ....
 
 Now that a snapshot exists, `zfs send` can be used to create a stream representing the contents of the snapshot.
 This stream can be stored as a file or received by another pool.
 The stream is written to standard output, but must be redirected to a file or pipe or an error is produced:
 
 [source,shell]
 ....
 # zfs send mypool@backup1
 Error: Stream can not be written to a terminal.
 You must redirect standard output.
 ....
 
 To back up a dataset with `zfs send`, redirect to a file located on the mounted backup pool.
 Ensure that the pool has enough free space to accommodate the size of the snapshot being sent, which means all of the data contained in the snapshot, not just the changes from the previous snapshot.
 
 [source,shell]
 ....
 # zfs send mypool@backup1 > /backup/backup1
 # zpool list
 NAME    SIZE  ALLOC   FREE   CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
 backup  960M  63.7M   896M         -         -     0%     6%  1.00x  ONLINE  -
 mypool  984M  43.7M   940M         -         -     0%     4%  1.00x  ONLINE  -
 ....
 
 The `zfs send` transferred all the data in the snapshot called _backup1_ to the pool named _backup_.
 Creating and sending these snapshots can be done automatically with a man:cron[8] job.
 
 Instead of storing the backups as archive files, ZFS can receive them as a live file system, allowing the backed up data to be accessed directly.
 To get to the actual data contained in those streams, `zfs receive` is used to transform the streams back into files and directories.
 The example below combines `zfs send` and `zfs receive` using a pipe to copy the data from one pool to another.
 The data can be used directly on the receiving pool after the transfer is complete.
 A dataset can only be replicated to an empty dataset.
 
 [source,shell]
 ....
 # zfs snapshot mypool@replica1
 # zfs send -v mypool@replica1 | zfs receive backup/mypool
 send from @ to mypool@replica1 estimated size is 50.1M
 total estimated size is 50.1M
 TIME        SENT   SNAPSHOT
 
 # zpool list
 NAME    SIZE  ALLOC   FREE   CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
 backup  960M  63.7M   896M         -         -     0%     6%  1.00x  ONLINE  -
 mypool  984M  43.7M   940M         -         -     0%     4%  1.00x  ONLINE  -
 ....
 
 [[zfs-send-incremental]]
 ==== Incremental Backups
 
 `zfs send` can also determine the difference between two snapshots and send only the differences between the two.
 This saves disk space and transfer time.
 For example:
 
 [source,shell]
 ....
 # zfs snapshot mypool@replica2
 # zfs list -t snapshot
 NAME                    USED  AVAIL  REFER  MOUNTPOINT
 mypool@replica1         5.72M      -  43.6M  -
 mypool@replica2             0      -  44.1M  -
 # zpool list
 NAME    SIZE  ALLOC   FREE   CKPOINT  EXPANDSZ   FRAG   CAP  DEDUP  HEALTH  ALTROOT
 backup  960M  61.7M   898M         -         -     0%    6%  1.00x  ONLINE  -
 mypool  960M  50.2M   910M         -         -     0%    5%  1.00x  ONLINE  -
 ....
 
 A second snapshot called _replica2_ was created.
 This second snapshot contains only the changes that were made to the file system between now and the previous snapshot, _replica1_.
 Using `zfs send -i` and indicating the pair of snapshots generates an incremental replica stream containing only the data that has changed.
 This can only succeed if the initial snapshot already exists on the receiving side.
 
 [source,shell]
 ....
 # zfs send -v -i mypool@replica1 mypool@replica2 | zfs receive /backup/mypool
 send from @replica1 to mypool@replica2 estimated size is 5.02M
 total estimated size is 5.02M
 TIME        SENT   SNAPSHOT
 
 # zpool list
 NAME    SIZE  ALLOC   FREE   CKPOINT  EXPANDSZ   FRAG  CAP  DEDUP  HEALTH  ALTROOT
 backup  960M  80.8M   879M         -         -     0%   8%  1.00x  ONLINE  -
 mypool  960M  50.2M   910M         -         -     0%   5%  1.00x  ONLINE  -
 
 # zfs list
 NAME                         USED  AVAIL  REFER  MOUNTPOINT
 backup                      55.4M   240G   152K  /backup
 backup/mypool               55.3M   240G  55.2M  /backup/mypool
 mypool                      55.6M  11.6G  55.0M  /mypool
 
 # zfs list -t snapshot
 NAME                                         USED  AVAIL  REFER  MOUNTPOINT
 backup/mypool@replica1                       104K      -  50.2M  -
 backup/mypool@replica2                          0      -  55.2M  -
 mypool@replica1                             29.9K      -  50.0M  -
 mypool@replica2                                 0      -  55.0M  -
 ....
 
 The incremental stream was successfully transferred.
 Only the data that had changed was replicated, rather than the entirety of _replica1_.
 Only the differences were sent, which took much less time to transfer and saved disk space by not copying the complete pool each time.
 This is useful when having to rely on slow networks or when costs per transferred byte must be considered.
 
 A new file system, _backup/mypool_, is available with all of the files and data from the pool _mypool_.
 If `-P` is specified, the properties of the dataset will be copied, including compression settings, quotas, and mount points.
 When `-R` is specified, all child datasets of the indicated dataset will be copied, along with all of their properties.
 Sending and receiving can be automated so that regular backups are created on the second pool.
 
 [[zfs-send-ssh]]
 ==== Sending Encrypted Backups over SSH
 
 Sending streams over the network is a good way to keep a remote backup, but it does come with a drawback.
 Data sent over the network link is not encrypted, allowing anyone to intercept and transform the streams back into data without the knowledge of the sending user.
 This is undesirable, especially when sending the streams over the internet to a remote host.
 SSH can be used to securely encrypt data send over a network connection.
 Since ZFS only requires the stream to be redirected from standard output, it is relatively easy to pipe it through SSH.
 To keep the contents of the file system encrypted in transit and on the remote system, consider using https://wiki.freebsd.org/PEFS[PEFS].
 
 A few settings and security precautions must be completed first.
 Only the necessary steps required for the `zfs send` operation are shown here.
 For more information on SSH, see crossref:security[openssh,"OpenSSH"].
 
 This configuration is required:
 
 * Passwordless SSH access between sending and receiving host using SSH keys
 * Normally, the privileges of the `root` user are needed to send and receive streams. This requires logging in to the receiving system as `root`. However, logging in as `root` is disabled by default for security reasons. The <<zfs-zfs-allow,ZFS Delegation>> system can be used to allow a non-`root` user on each system to perform the respective send and receive operations.
 * On the sending system:
 +
 [source,shell]
 ....
 # zfs allow -u someuser send,snapshot mypool
 ....
 
 * To mount the pool, the unprivileged user must own the directory, and regular users must be allowed to mount file systems. On the receiving system:
 +
 [source,shell]
 ....
 # sysctl vfs.usermount=1
 vfs.usermount: 0 -> 1
 # echo vfs.usermount=1 >> /etc/sysctl.conf
 # zfs create recvpool/backup
 # zfs allow -u someuser create,mount,receive recvpool/backup
 # chown someuser /recvpool/backup
 ....
 
 The unprivileged user now has the ability to receive and mount datasets, and the _home_ dataset can be replicated to the remote system:
 
 [source,shell]
 ....
 % zfs snapshot -r mypool/home@monday
 % zfs send -R mypool/home@monday | ssh someuser@backuphost zfs recv -dvu recvpool/backup
 ....
 
 A recursive snapshot called _monday_ is made of the file system dataset _home_ that resides on the pool _mypool_.
 Then it is sent with `zfs send -R` to include the dataset, all child datasets, snapshots, clones, and settings in the stream.
 The output is piped to the waiting `zfs receive` on the remote host _backuphost_ through SSH.
 Using a fully qualified domain name or IP address is recommended.
 The receiving machine writes the data to the _backup_ dataset on the _recvpool_ pool.
 Adding `-d` to `zfs recv` overwrites the name of the pool on the receiving side with the name of the snapshot.
 `-u` causes the file systems to not be mounted on the receiving side.
 When `-v` is included, more detail about the transfer is shown, including elapsed time and the amount of data transferred.
 
 [[zfs-zfs-quota]]
 === Dataset, User, and Group Quotas
 
 <<zfs-term-quota,Dataset quotas>> are used to restrict the amount of space that can be consumed by a particular dataset.
 <<zfs-term-refquota,Reference Quotas>> work in very much the same way, but only count the space used by the dataset itself, excluding snapshots and child datasets.
 Similarly, <<zfs-term-userquota,user>> and <<zfs-term-groupquota,group>> quotas can be used to prevent users or groups from using all of the space in the pool or dataset.
 
 The following examples assume that the users already exist in the system.
 Before adding a user to the system, make sure to create their home dataset first and set the `mountpoint` to `/home/_bob_`.
 Then, create the user and make the home directory point to the dataset's `mountpoint` location.
 This will properly set owner and group permissions without shadowing any pre-existing home directory paths that might exist.
 
 To enforce a dataset quota of 10 GB for [.filename]#storage/home/bob#:
 
 [source,shell]
 ....
 # zfs set quota=10G storage/home/bob
 ....
 
 To enforce a reference quota of 10 GB for [.filename]#storage/home/bob#:
 
 [source,shell]
 ....
 # zfs set refquota=10G storage/home/bob
 ....
 
 To remove a quota of 10 GB for [.filename]#storage/home/bob#:
 
 [source,shell]
 ....
 # zfs set quota=none storage/home/bob
 ....
 
 The general format is `userquota@_user_=_size_`, and the user's name must be in one of these formats:
 
 * POSIX compatible name such as _joe_.
 * POSIX numeric ID such as _789_.
 * SID name such as _joe.bloggs@example.com_.
 * SID numeric ID such as _S-1-123-456-789_.
 
 For example, to enforce a user quota of 50 GB for the user named _joe_:
 
 [source,shell]
 ....
 # zfs set userquota@joe=50G
 ....
 
 To remove any quota:
 
 [source,shell]
 ....
 # zfs set userquota@joe=none
 ....
 
 [NOTE]
 ====
 User quota properties are not displayed by `zfs get all`.
 Non-`root` users can only see their own quotas unless they have been granted the `userquota` privilege.
 Users with this privilege are able to view and set everyone's quota.
 ====
 
 The general format for setting a group quota is: `groupquota@_group_=_size_`.
 
 To set the quota for the group _firstgroup_ to 50 GB, use:
 
 [source,shell]
 ....
 # zfs set groupquota@firstgroup=50G
 ....
 
 To remove the quota for the group _firstgroup_, or to make sure that one is not set, instead use:
 
 [source,shell]
 ....
 # zfs set groupquota@firstgroup=none
 ....
 
 As with the user quota property, non-`root` users can only see the quotas associated with the groups to which they belong.
 However, `root` or a user with the `groupquota` privilege can view and set all quotas for all groups.
 
 To display the amount of space used by each user on a file system or snapshot along with any quotas, use `zfs userspace`.
 For group information, use `zfs groupspace`.
 For more information about supported options or how to display only specific options, refer to man:zfs[1].
 
 Users with sufficient privileges, and `root`, can list the quota for [.filename]#storage/home/bob# using:
 
 [source,shell]
 ....
 # zfs get quota storage/home/bob
 ....
 
 [[zfs-zfs-reservation]]
 === Reservations
 
 <<zfs-term-reservation,Reservations>> guarantee a minimum amount of space will always be available on a dataset.
 The reserved space will not be available to any other dataset.
 This feature can be especially useful to ensure that free space is available for an important dataset or log files.
 
 The general format of the `reservation` property is `reservation=_size_`, so to set a reservation of 10 GB on [.filename]#storage/home/bob#, use:
 
 [source,shell]
 ....
 # zfs set reservation=10G storage/home/bob
 ....
 
 To clear any reservation:
 
 [source,shell]
 ....
 # zfs set reservation=none storage/home/bob
 ....
 
 The same principle can be applied to the `refreservation` property for setting a <<zfs-term-refreservation,Reference Reservation>>, with the general format `refreservation=_size_`.
 
 This command shows any reservations or refreservations that exist on [.filename]#storage/home/bob#:
 
 [source,shell]
 ....
 # zfs get reservation storage/home/bob
 # zfs get refreservation storage/home/bob
 ....
 
 [[zfs-zfs-compression]]
 === Compression
 
 ZFS provides transparent compression.
 Compressing data at the block level as it is written not only saves space, but can also increase disk throughput.
 If data is compressed by 25%, but the compressed data is written to the disk at the same rate as the uncompressed version, resulting in an effective write speed of 125%.
 Compression can also be a great alternative to <<zfs-zfs-deduplication,Deduplication>> because it does not require additional memory.
 
 ZFS offers several different compression algorithms, each with different trade-offs.
 With the introduction of LZ4 compression in ZFS v5000, it is possible to enable compression for the entire pool without the large performance trade-off of other algorithms.
 The biggest advantage to LZ4 is the _early abort_ feature.
 If LZ4 does not achieve at least 12.5% compression in the first part of the data, the block is written uncompressed to avoid wasting CPU cycles trying to compress data that is either already compressed or uncompressible.
 For details about the different compression algorithms available in ZFS, see the <<zfs-term-compression,Compression>> entry in the terminology section.
 
 The administrator can monitor the effectiveness of compression using a number of dataset properties.
 
 [source,shell]
 ....
 # zfs get used,compressratio,compression,logicalused mypool/compressed_dataset
 NAME        PROPERTY          VALUE     SOURCE
 mypool/compressed_dataset  used              449G      -
 mypool/compressed_dataset  compressratio     1.11x     -
 mypool/compressed_dataset  compression       lz4       local
 mypool/compressed_dataset  logicalused       496G      -
 ....
 
 The dataset is currently using 449 GB of space (the used property).
 Without compression, it would have taken 496 GB of space (the `logicalused` property).
 This results in the 1.11:1 compression ratio.
 
 Compression can have an unexpected side effect when combined with <<zfs-term-userquota,User Quotas>>.
 User quotas restrict how much space a user can consume on a dataset, but the measurements are based on how much space is used _after compression_.
 So if a user has a quota of 10 GB, and writes 10 GB of compressible data, they will still be able to store additional data.
 If they later update a file, say a database, with more or less compressible data, the amount of space available to them will change.
 This can result in the odd situation where a user did not increase the actual amount of data (the `logicalused` property), but the change in compression caused them to reach their quota limit.
 
 Compression can have a similar unexpected interaction with backups.
 Quotas are often used to limit how much data can be stored to ensure there is sufficient backup space available.
 However since quotas do not consider compression, more data may be written than would fit with uncompressed backups.
 
 [[zfs-zfs-compression-zstd]]
 === Zstandard Compression
 
 In OpenZFS 2.0, a new compression algorithm was added.
 Zstandard (Zstd) offers higher compression ratios than the default LZ4 while offering much greater speeds than the alternative, gzip. OpenZFS 2.0 is available starting with FreeBSD 12.1-RELEASE via package:sysutils/openzfs[] and has been the default in FreeBSD 13-CURRENT since September 2020, and will by in FreeBSD 13.0-RELEASE.
 
 Zstd provides a large selection of compression levels, providing fine-grained control over performance versus compression ratio.
 One of the main advantages of Zstd is that the decompression speed is independent of the compression level.
 For data that is written once but read many times, Zstd allows the use of the highest compression levels without a read performance penalty.
 
 Even when data is updated frequently, there are often performance gains that come from enabling compression.
 One of the biggest advantages comes from the compressed ARC feature.
 ZFS's Adaptive Replacement Cache (ARC) caches the compressed version of the data in RAM, decompressing it each time it is needed.
 This allows the same amount of RAM to store more data and metadata, increasing the cache hit ratio.
 
 ZFS offers 19 levels of Zstd compression, each offering incrementally more space savings in exchange for slower compression.
 The default level is `zstd-3` and offers greater compression than LZ4 without being significantly slower.
 Levels above 10 require significant amounts of memory to compress each block, so they are discouraged on systems with less than 16 GB of RAM.
 ZFS also implements a selection of the Zstd_fast_ levels, which get correspondingly faster but offer lower compression ratios.
 ZFS supports `zstd-fast-1` through `zstd-fast-10`, `zstd-fast-20` through `zstd-fast-100` in increments of 10, and finally `zstd-fast-500` and `zstd-fast-1000` which provide minimal compression, but offer very high performance.
 
 If ZFS is not able to allocate the required memory to compress a block with Zstd, it will fall back to storing the block uncompressed.
 This is unlikely to happen outside of the highest levels of Zstd on systems that are memory constrained.
 The sysctl `kstat.zfs.misc.zstd.compress_alloc_fail` counts how many times this has occurred since the ZFS module was loaded.
 
 [[zfs-zfs-deduplication]]
 === Deduplication
 
 When enabled, <<zfs-term-deduplication,deduplication>> uses the checksum of each block to detect duplicate blocks.
 When a new block is a duplicate of an existing block, ZFS writes an additional reference to the existing data instead of the whole duplicate block.
 Tremendous space savings are possible if the data contains many duplicated files or repeated information.
 Be warned: deduplication requires an extremely large amount of memory, and most of the space savings can be had without the extra cost by enabling compression instead.
 
 To activate deduplication, set the `dedup` property on the target pool:
 
 [source,shell]
 ....
 # zfs set dedup=on pool
 ....
 
 Only new data being written to the pool will be deduplicated.
 Data that has already been written to the pool will not be deduplicated merely by activating this option.
 A pool with a freshly activated deduplication property will look like this example:
 
 [source,shell]
 ....
 # zpool list
 NAME  SIZE ALLOC  FREE   CKPOINT  EXPANDSZ   FRAG   CAP   DEDUP   HEALTH   ALTROOT
 pool 2.84G 2.19M 2.83G         -         -     0%    0%   1.00x   ONLINE   -
 ....
 
 The `DEDUP` column shows the actual rate of deduplication for the pool.
 A value of `1.00x` shows that data has not been deduplicated yet.
 In the next example, the ports tree is copied three times into different directories on the deduplicated pool created above.
 
 [source,shell]
 ....
 # for d in dir1 dir2 dir3; do
 > mkdir $d && cp -R /usr/ports $d &
 > done
 ....
 
 Redundant data is detected and deduplicated:
 
 [source,shell]
 ....
 # zpool list
 NAME SIZE  ALLOC  FREE   CKPOINT  EXPANDSZ   FRAG  CAP   DEDUP   HEALTH   ALTROOT
 pool 2.84G 20.9M 2.82G         -         -     0%   0%   3.00x   ONLINE   -
 ....
 
 The `DEDUP` column shows a factor of `3.00x`.
 Multiple copies of the ports tree data was detected and deduplicated, using only a third of the space.
 The potential for space savings can be enormous, but comes at the cost of having enough memory to keep track of the deduplicated blocks.
 
 Deduplication is not always beneficial, especially when the data on a pool is not redundant.
 ZFS can show potential space savings by simulating deduplication on an existing pool:
 
 [source,shell]
 ....
 # zdb -S pool
 Simulated DDT histogram:
 
 bucket              allocated                       referenced
 ______   ______________________________   ______________________________
 refcnt   blocks   LSIZE   PSIZE   DSIZE   blocks   LSIZE   PSIZE   DSIZE
 ------   ------   -----   -----   -----   ------   -----   -----   -----
      1    2.58M    289G    264G    264G    2.58M    289G    264G    264G
      2     206K   12.6G   10.4G   10.4G     430K   26.4G   21.6G   21.6G
      4    37.6K    692M    276M    276M     170K   3.04G   1.26G   1.26G
      8    2.18K   45.2M   19.4M   19.4M    20.0K    425M    176M    176M
     16      174   2.83M   1.20M   1.20M    3.33K   48.4M   20.4M   20.4M
     32       40   2.17M    222K    222K    1.70K   97.2M   9.91M   9.91M
     64        9     56K   10.5K   10.5K      865   4.96M    948K    948K
    128        2   9.50K      2K      2K      419   2.11M    438K    438K
    256        5   61.5K     12K     12K    1.90K   23.0M   4.47M   4.47M
     1K        2      1K      1K      1K    2.98K   1.49M   1.49M   1.49M
  Total    2.82M    303G    275G    275G    3.20M    319G    287G    287G
 
 dedup = 1.05, compress = 1.11, copies = 1.00, dedup * compress / copies = 1.16
 ....
 
 After `zdb -S` finishes analyzing the pool, it shows the space reduction ratio that would be achieved by activating deduplication.
 In this case, `1.16` is a very poor space saving ratio that is mostly provided by compression.
 Activating deduplication on this pool would not save any significant amount of space, and is not worth the amount of memory required to enable deduplication.
 Using the formula _ratio = dedup * compress / copies_, system administrators can plan the storage allocation, deciding whether the workload will contain enough duplicate blocks to justify the memory requirements.
 If the data is reasonably compressible, the space savings may be very good.
 Enabling compression first is recommended, and compression can also provide greatly increased performance.
 Only enable deduplication in cases where the additional savings will be considerable and there is sufficient memory for the <<zfs-term-deduplication,DDT>>.
 
 [[zfs-zfs-jail]]
 === ZFS and Jails
 
 `zfs jail` and the corresponding `jailed` property are used to delegate a ZFS dataset to a crossref:jails[jails,Jail].
 `zfs jail _jailid_` attaches a dataset to the specified jail, and `zfs unjail` detaches it.
 For the dataset to be controlled from within a jail, the `jailed` property must be set.
 Once a dataset is jailed, it can no longer be mounted on the host because it may have mount points that would compromise the security of the host.
 
 [[zfs-zfs-allow]]
 == Delegated Administration
 
 A comprehensive permission delegation system allows unprivileged users to perform ZFS administration functions.
 For example, if each user's home directory is a dataset, users can be given permission to create and destroy snapshots of their home directories.
 A backup user can be given permission to use replication features.
 A usage statistics script can be allowed to run with access only to the space utilization data for all users.
 It is even possible to delegate the ability to delegate permissions.
 Permission delegation is possible for each subcommand and most properties.
 
 [[zfs-zfs-allow-create]]
 === Delegating Dataset Creation
 
 `zfs allow _someuser_ create _mydataset_` gives the specified user permission to create child datasets under the selected parent dataset.
 There is a caveat: creating a new dataset involves mounting it.
 That requires setting the FreeBSD `vfs.usermount` man:sysctl[8] to `1` to allow non-root users to mount a file system.
 There is another restriction aimed at preventing abuse: non-`root` users must own the mountpoint where the file system is to be mounted.
 
 [[zfs-zfs-allow-allow]]
 === Delegating Permission Delegation
 
 `zfs allow _someuser_ allow _mydataset_` gives the specified user the ability to assign any permission they have on the target dataset, or its children, to other users.
 If a user has the `snapshot` permission and the `allow` permission, that user can then grant the `snapshot` permission to other users.
 
 [[zfs-advanced]]
 == Advanced Topics
 
 [[zfs-advanced-tuning]]
 === Tuning
 
 There are a number of tunables that can be adjusted to make ZFS perform best for different workloads.
 
 * [[zfs-advanced-tuning-arc_max]] `_vfs.zfs.arc_max_` - Maximum size of the <<zfs-term-arc,ARC>>. The default is all RAM but 1 GB, or 5/8 of all RAM, whichever is more. However, a lower value should be used if the system will be running any other daemons or processes that may require memory. This value can be adjusted at runtime with man:sysctl[8] and can be set in [.filename]#/boot/loader.conf# or [.filename]#/etc/sysctl.conf#.
 * [[zfs-advanced-tuning-arc_meta_limit]] `_vfs.zfs.arc_meta_limit_` - Limit the portion of the <<zfs-term-arc,ARC>> that can be used to store metadata. The default is one fourth of `vfs.zfs.arc_max`. Increasing this value will improve performance if the workload involves operations on a large number of files and directories, or frequent metadata operations, at the cost of less file data fitting in the <<zfs-term-arc,ARC>>. This value can be adjusted at runtime with man:sysctl[8] and can be set in [.filename]#/boot/loader.conf# or [.filename]#/etc/sysctl.conf#.
 * [[zfs-advanced-tuning-arc_min]] `_vfs.zfs.arc_min_` - Minimum size of the <<zfs-term-arc,ARC>>. The default is one half of `vfs.zfs.arc_meta_limit`. Adjust this value to prevent other applications from pressuring out the entire <<zfs-term-arc,ARC>>. This value can be adjusted at runtime with man:sysctl[8] and can be set in [.filename]#/boot/loader.conf# or [.filename]#/etc/sysctl.conf#.
 * [[zfs-advanced-tuning-vdev-cache-size]] `_vfs.zfs.vdev.cache.size_` - A preallocated amount of memory reserved as a cache for each device in the pool. The total amount of memory used will be this value multiplied by the number of devices. This value can only be adjusted at boot time, and is set in [.filename]#/boot/loader.conf#.
 * [[zfs-advanced-tuning-min-auto-ashift]] `_vfs.zfs.min_auto_ashift_` - Minimum `ashift` (sector size) that will be used automatically at pool creation time. The value is a power of two. The default value of `9` represents `2^9 = 512`, a sector size of 512 bytes. To avoid _write amplification_ and get the best performance, set this value to the largest sector size used by a device in the pool.
-+ 
++
 Many drives have 4 KB sectors.
 Using the default `ashift` of `9` with these drives results in write amplification on these devices.
 Data that could be contained in a single 4 KB write must instead be written in eight 512-byte writes.
 ZFS tries to read the native sector size from all devices when creating a pool, but many drives with 4 KB sectors report that their sectors are 512 bytes for compatibility.
 Setting `vfs.zfs.min_auto_ashift` to `12` (`2^12 = 4096`) before creating a pool forces ZFS to use 4 KB blocks for best performance on these drives.
-+ 
++
 Forcing 4 KB blocks is also useful on pools where disk upgrades are planned.
 Future disks are likely to use 4 KB sectors, and `ashift` values cannot be changed after a pool is created.
-+ 
++
 In some specific cases, the smaller 512-byte block size might be preferable.
 When used with 512-byte disks for databases, or as storage for virtual machines, less data is transferred during small random reads.
 This can provide better performance, especially when using a smaller ZFS record size.
 * [[zfs-advanced-tuning-prefetch_disable]] `_vfs.zfs.prefetch_disable_` - Disable prefetch. A value of `0` is enabled and `1` is disabled. The default is `0`, unless the system has less than 4 GB of RAM. Prefetch works by reading larger blocks than were requested into the <<zfs-term-arc,ARC>> in hopes that the data will be needed soon. If the workload has a large number of random reads, disabling prefetch may actually improve performance by reducing unnecessary reads. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-vdev-trim_on_init]] `_vfs.zfs.vdev.trim_on_init_` - Control whether new devices added to the pool have the `TRIM` command run on them. This ensures the best performance and longevity for SSDs, but takes extra time. If the device has already been secure erased, disabling this setting will make the addition of the new device faster. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-vdev-max_pending]] `_vfs.zfs.vdev.max_pending_` - Limit the number of pending I/O requests per device. A higher value will keep the device command queue full and may give higher throughput. A lower value will reduce latency. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-top_maxinflight]] `_vfs.zfs.top_maxinflight_` - Maximum number of outstanding I/Os per top-level <<zfs-term-vdev,vdev>>. Limits the depth of the command queue to prevent high latency. The limit is per top-level vdev, meaning the limit applies to each <<zfs-term-vdev-mirror,mirror>>, <<zfs-term-vdev-raidz,RAID-Z>>, or other vdev independently. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-l2arc_write_max]] `_vfs.zfs.l2arc_write_max_` - Limit the amount of data written to the <<zfs-term-l2arc,L2ARC>> per second. This tunable is designed to extend the longevity of SSDs by limiting the amount of data written to the device. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-l2arc_write_boost]] `_vfs.zfs.l2arc_write_boost_` - The value of this tunable is added to <<zfs-advanced-tuning-l2arc_write_max,`vfs.zfs.l2arc_write_max`>> and increases the write speed to the SSD until the first block is evicted from the <<zfs-term-l2arc,L2ARC>>. This "Turbo Warmup Phase" is designed to reduce the performance loss from an empty <<zfs-term-l2arc,L2ARC>> after a reboot. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-scrub_delay]]`_vfs.zfs.scrub_delay_` - Number of ticks to delay between each I/O during a <<zfs-term-scrub,`scrub`>>. To ensure that a `scrub` does not interfere with the normal operation of the pool, if any other I/O is happening the `scrub` will delay between each command. This value controls the limit on the total IOPS (I/Os Per Second) generated by the `scrub`. The granularity of the setting is determined by the value of `kern.hz` which defaults to 1000 ticks per second. This setting may be changed, resulting in a different effective IOPS limit. The default value is `4`, resulting in a limit of: 1000 ticks/sec / 4 = 250 IOPS. Using a value of _20_ would give a limit of: 1000 ticks/sec / 20 = 50 IOPS. The speed of `scrub` is only limited when there has been recent activity on the pool, as determined by <<zfs-advanced-tuning-scan_idle,`vfs.zfs.scan_idle`>>. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-resilver_delay]] `_vfs.zfs.resilver_delay_` - Number of milliseconds of delay inserted between each I/O during a <<zfs-term-resilver,resilver>>. To ensure that a resilver does not interfere with the normal operation of the pool, if any other I/O is happening the resilver will delay between each command. This value controls the limit of total IOPS (I/Os Per Second) generated by the resilver. The granularity of the setting is determined by the value of `kern.hz` which defaults to 1000 ticks per second. This setting may be changed, resulting in a different effective IOPS limit. The default value is 2, resulting in a limit of: 1000 ticks/sec / 2 = 500 IOPS. Returning the pool to an <<zfs-term-online,Online>> state may be more important if another device failing could <<zfs-term-faulted,Fault>> the pool, causing data loss. A value of 0 will give the resilver operation the same priority as other operations, speeding the healing process. The speed of resilver is only limited when there has been other recent activity on the pool, as determined by <<zfs-advanced-tuning-scan_idle,`vfs.zfs.scan_idle`>>. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-scan_idle]] `_vfs.zfs.scan_idle_` - Number of milliseconds since the last operation before the pool is considered idle. When the pool is idle the rate limiting for <<zfs-term-scrub,`scrub`>> and <<zfs-term-resilver,resilver>> are disabled. This value can be adjusted at any time with man:sysctl[8].
 * [[zfs-advanced-tuning-txg-timeout]] `_vfs.zfs.txg.timeout_` - Maximum number of seconds between <<zfs-term-txg,transaction group>>s. The current transaction group will be written to the pool and a fresh transaction group started if this amount of time has elapsed since the previous transaction group. A transaction group my be triggered earlier if enough data is written. The default value is 5 seconds. A larger value may improve read performance by delaying asynchronous writes, but this may cause uneven performance when the transaction group is written. This value can be adjusted at any time with man:sysctl[8].
 
 [[zfs-advanced-i386]]
 === ZFS on i386
 
 Some of the features provided by ZFS are memory intensive, and may require tuning for maximum efficiency on systems with limited RAM.
 
 ==== Memory
 
 As a bare minimum, the total system memory should be at least one gigabyte.
 The amount of recommended RAM depends upon the size of the pool and which ZFS features are used.
 A general rule of thumb is 1 GB of RAM for every 1 TB of storage.
 If the deduplication feature is used, a general rule of thumb is 5 GB of RAM per TB of storage to be deduplicated.
 While some users successfully use ZFS with less RAM, systems under heavy load may panic due to memory exhaustion.
 Further tuning may be required for systems with less than the recommended RAM requirements.
 
 ==== Kernel Configuration
 
 Due to the address space limitations of the i386(TM) platform, ZFS users on the i386(TM) architecture must add this option to a custom kernel configuration file, rebuild the kernel, and reboot:
 
 [.programlisting]
 ....
 options        KVA_PAGES=512
 ....
 
 This expands the kernel address space, allowing the `vm.kvm_size` tunable to be pushed beyond the currently imposed limit of 1 GB, or the limit of 2 GB for PAE.
 To find the most suitable value for this option, divide the desired address space in megabytes by four.
 In this example, it is `512` for 2 GB.
 
 ==== Loader Tunables
 
 The [.filename]#kmem# address space can be increased on all FreeBSD architectures.
 On a test system with 1 GB of physical memory, success was achieved with these options added to [.filename]#/boot/loader.conf#, and the system restarted:
 
 [.programlisting]
 ....
 vm.kmem_size="330M"
 vm.kmem_size_max="330M"
 vfs.zfs.arc_max="40M"
 vfs.zfs.vdev.cache.size="5M"
 ....
 
 For a more detailed list of recommendations for ZFS-related tuning, see https://wiki.freebsd.org/ZFSTuningGuide[].
 
 [[zfs-links]]
 == Additional Resources
 
 * http://open-zfs.org[OpenZFS]
 * https://wiki.freebsd.org/ZFSTuningGuide[FreeBSD Wiki - ZFS Tuning]
 * http://docs.oracle.com/cd/E19253-01/819-5461/index.html[Oracle Solaris ZFS Administration Guide]
 * https://calomel.org/zfs_raid_speed_capacity.html[Calomel Blog - ZFS Raidz Performance, Capacity and Integrity]
 
 [[zfs-term]]
 == ZFS Features and Terminology
 
 ZFS is a fundamentally different file system because it is more than just a file system.
 ZFS combines the roles of file system and volume manager, enabling additional storage devices to be added to a live system and having the new space available on all of the existing file systems in that pool immediately.
 By combining the traditionally separate roles, ZFS is able to overcome previous limitations that prevented RAID groups being able to grow.
 Each top level device in a pool is called a _vdev_, which can be a simple disk or a RAID transformation such as a mirror or RAID-Z array.
 ZFS file systems (called _datasets_) each have access to the combined free space of the entire pool.
 As blocks are allocated from the pool, the space available to each file system decreases.
 This approach avoids the common pitfall with extensive partitioning where free space becomes fragmented across the partitions.
 
 [.informaltable]
 [cols="10%,90%"]
 |===
 
 |[[zfs-term-pool]]pool
 |A storage _pool_ is the most basic building block of ZFS. A pool is made up of one or more vdevs, the underlying devices that store the data. A pool is then used to create one or more file systems (datasets) or block devices (volumes). These datasets and volumes share the pool of remaining free space. Each pool is uniquely identified by a name and a GUID. The features available are determined by the ZFS version number on the pool.
 
 |[[zfs-term-vdev]]vdev Types
 a|A pool is made up of one or more vdevs, which themselves can be a single disk or a group of disks, in the case of a RAID transform. When multiple vdevs are used, ZFS spreads data across the vdevs to increase performance and maximize usable space. 
 
 * [[zfs-term-vdev-disk]] _Disk_ - The most basic type of vdev is a standard block device. This can be an entire disk (such as [.filename]#/dev/ada0# or [.filename]#/dev/da0#) or a partition ([.filename]#/dev/ada0p3#). On FreeBSD, there is no performance penalty for using a partition rather than the entire disk. This differs from recommendations made by the Solaris documentation.
 +
 [CAUTION]
 ====
 Using an entire disk as part of a bootable pool is strongly discouraged, as this may render the pool unbootable.
 Likewise, you should not use an entire disk as part of a mirror or RAID-Z vdev.
 These are because it is impossible to reliably determine the size of an unpartitioned disk at boot time and because there's no place to put in boot code.
 ====
 
 * [[zfs-term-vdev-file]] _File_ - In addition to disks, ZFS pools can be backed by regular files, this is especially useful for testing and experimentation. Use the full path to the file as the device path in `zpool create`. All vdevs must be at least 128 MB in size.
 * [[zfs-term-vdev-mirror]] _Mirror_ - When creating a mirror, specify the `mirror` keyword followed by the list of member devices for the mirror. A mirror consists of two or more devices, all data will be written to all member devices. A mirror vdev will only hold as much data as its smallest member. A mirror vdev can withstand the failure of all but one of its members without losing any data.
 +
 [NOTE]
 ====
 A regular single disk vdev can be upgraded to a mirror vdev at any time with `zpool <<zfs-zpool-attach,attach>>`.
 ====
 
 * [[zfs-term-vdev-raidz]] _RAID-Z_ - ZFS implements RAID-Z, a variation on standard RAID-5 that offers better distribution of parity and eliminates the "RAID-5 write hole" in which the data and parity information become inconsistent after an unexpected restart. ZFS supports three levels of RAID-Z which provide varying levels of redundancy in exchange for decreasing levels of usable storage. The types are named RAID-Z1 through RAID-Z3 based on the number of parity devices in the array and the number of disks which can fail while the pool remains operational.
-+ 
++
 In a RAID-Z1 configuration with four disks, each 1 TB, usable storage is 3 TB and the pool will still be able to operate in degraded mode with one faulted disk. If an additional disk goes offline before the faulted disk is replaced and resilvered, all data in the pool can be lost.
-+ 
++
 In a RAID-Z3 configuration with eight disks of 1 TB, the volume will provide 5 TB of usable space and still be able to operate with three faulted disks. Sun(TM) recommends no more than nine disks in a single vdev. If the configuration has more disks, it is recommended to divide them into separate vdevs and the pool data will be striped across them.
-+ 
++
 A configuration of two RAID-Z2 vdevs consisting of 8 disks each would create something similar to a RAID-60 array. A RAID-Z group's storage capacity is approximately the size of the smallest disk multiplied by the number of non-parity disks. Four 1 TB disks in RAID-Z1 has an effective size of approximately 3 TB, and an array of eight 1 TB disks in RAID-Z3 will yield 5 TB of usable space.
 * [[zfs-term-vdev-spare]] _Spare_ - ZFS has a special pseudo-vdev type for keeping track of available hot spares. Note that installed hot spares are not deployed automatically; they must manually be configured to replace the failed device using `zfs replace`.
 * [[zfs-term-vdev-log]] _Log_ - ZFS Log Devices, also known as ZFS Intent Log (<<zfs-term-zil,ZIL>>) move the intent log from the regular pool devices to a dedicated device, typically an SSD. Having a dedicated log device can significantly improve the performance of applications with a high volume of synchronous writes, especially databases. Log devices can be mirrored, but RAID-Z is not supported. If multiple log devices are used, writes will be load balanced across them.
 * [[zfs-term-vdev-cache]] _Cache_ - Adding a cache vdev to a pool will add the storage of the cache to the <<zfs-term-l2arc,L2ARC>>. Cache devices cannot be mirrored. Since a cache device only stores additional copies of existing data, there is no risk of data loss.
 
 |[[zfs-term-txg]] Transaction Group (TXG)
 |Transaction Groups are the way changed blocks are grouped together and eventually written to the pool. Transaction groups are the atomic unit that ZFS uses to assert consistency. Each transaction group is assigned a unique 64-bit consecutive identifier. There can be up to three active transaction groups at a time, one in each of these three states: 
 
 * _Open_ - When a new transaction group is created, it is in the open state, and accepts new writes. There is always a transaction group in the open state, however the transaction group may refuse new writes if it has reached a limit. Once the open transaction group has reached a limit, or the <<zfs-advanced-tuning-txg-timeout,`vfs.zfs.txg.timeout`>> has been reached, the transaction group advances to the next state.
 * _Quiescing_ - A short state that allows any pending operations to finish while not blocking the creation of a new open transaction group. Once all of the transactions in the group have completed, the transaction group advances to the final state.
 * _Syncing_ - All of the data in the transaction group is written to stable storage. This process will in turn modify other data, such as metadata and space maps, that will also need to be written to stable storage. The process of syncing involves multiple passes. The first, all of the changed data blocks, is the biggest, followed by the metadata, which may take multiple passes to complete. Since allocating space for the data blocks generates new metadata, the syncing state cannot finish until a pass completes that does not allocate any additional space. The syncing state is also where _synctasks_ are completed. Synctasks are administrative operations, such as creating or destroying snapshots and datasets, that modify the uberblock are completed. Once the sync state is complete, the transaction group in the quiescing state is advanced to the syncing state.
  All administrative functions, such as <<zfs-term-snapshot,`snapshot`>> are written as part of the transaction group. When a synctask is created, it is added to the currently open transaction group, and that group is advanced as quickly as possible to the syncing state to reduce the latency of administrative commands.
 
 |[[zfs-term-arc]]Adaptive Replacement Cache (ARC)
 |ZFS uses an Adaptive Replacement Cache (ARC), rather than a more traditional Least Recently Used (LRU) cache. An LRU cache is a simple list of items in the cache, sorted by when each object was most recently used. New items are added to the top of the list. When the cache is full, items from the bottom of the list are evicted to make room for more active objects. An ARC consists of four lists; the Most Recently Used (MRU) and Most Frequently Used (MFU) objects, plus a ghost list for each. These ghost lists track recently evicted objects to prevent them from being added back to the cache. This increases the cache hit ratio by avoiding objects that have a history of only being used occasionally. Another advantage of using both an MRU and MFU is that scanning an entire file system would normally evict all data from an MRU or LRU cache in favor of this freshly accessed content. With ZFS, there is also an MFU that only tracks the most frequently used objects, and the cache of the most commonly accessed blocks remains.
 
 |[[zfs-term-l2arc]]L2ARC
 |L2ARC is the second level of the ZFS caching system. The primary ARC is stored in RAM. Since the amount of available RAM is often limited, ZFS can also use <<zfs-term-vdev-cache,cache vdevs>>. Solid State Disks (SSDs) are often used as these cache devices due to their higher speed and lower latency compared to traditional spinning disks. L2ARC is entirely optional, but having one will significantly increase read speeds for files that are cached on the SSD instead of having to be read from the regular disks. L2ARC can also speed up <<zfs-term-deduplication,deduplication>> because a DDT that does not fit in RAM but does fit in the L2ARC will be much faster than a DDT that must be read from disk. The rate at which data is added to the cache devices is limited to prevent prematurely wearing out SSDs with too many writes. Until the cache is full (the first block has been evicted to make room), writing to the L2ARC is limited to the sum of the write limit and the boost limit, and afterwards limited to the write limit. A pair of man:sysctl[8] values control these rate limits. <<zfs-advanced-tuning-l2arc_write_max,`vfs.zfs.l2arc_write_max`>> controls how many bytes are written to the cache per second, while <<zfs-advanced-tuning-l2arc_write_boost,`vfs.zfs.l2arc_write_boost`>> adds to this limit during the "Turbo Warmup Phase" (Write Boost).
 
 |[[zfs-term-zil]]ZIL
 |ZIL accelerates synchronous transactions by using storage devices like SSDs that are faster than those used in the main storage pool. When an application requests a synchronous write (a guarantee that the data has been safely stored to disk rather than merely cached to be written later), the data is written to the faster ZIL storage, then later flushed out to the regular disks. This greatly reduces latency and improves performance. Only synchronous workloads like databases will benefit from a ZIL. Regular asynchronous writes such as copying files will not use the ZIL at all.
 
 |[[zfs-term-cow]]Copy-On-Write
 |Unlike a traditional file system, when data is overwritten on ZFS, the new data is written to a different block rather than overwriting the old data in place. Only when this write is complete is the metadata then updated to point to the new location. In the event of a shorn write (a system crash or power loss in the middle of writing a file), the entire original contents of the file are still available and the incomplete write is discarded. This also means that ZFS does not require a man:fsck[8] after an unexpected shutdown.
 
 |[[zfs-term-dataset]]Dataset
 |_Dataset_ is the generic term for a ZFS file system, volume, snapshot or clone. Each dataset has a unique name in the format _poolname/path@snapshot_. The root of the pool is technically a dataset as well. Child datasets are named hierarchically like directories. For example, _mypool/home_, the home dataset, is a child of _mypool_ and inherits properties from it. This can be expanded further by creating _mypool/home/user_. This grandchild dataset will inherit properties from the parent and grandparent. Properties on a child can be set to override the defaults inherited from the parents and grandparents. Administration of datasets and their children can be <<zfs-zfs-allow,delegated>>.
 
 |[[zfs-term-filesystem]]File system
 |A ZFS dataset is most often used as a file system. Like most other file systems, a ZFS file system is mounted somewhere in the systems directory hierarchy and contains files and directories of its own with permissions, flags, and other metadata.
 
 |[[zfs-term-volume]]Volume
 |In addition to regular file system datasets, ZFS can also create volumes, which are block devices. Volumes have many of the same features, including copy-on-write, snapshots, clones, and checksumming. Volumes can be useful for running other file system formats on top of ZFS, such as UFS virtualization, or exporting iSCSI extents.
 
 |[[zfs-term-snapshot]]Snapshot
 |The <<zfs-term-cow,copy-on-write>> (COW) design of ZFS allows for nearly instantaneous, consistent snapshots with arbitrary names. After taking a snapshot of a dataset, or a recursive snapshot of a parent dataset that will include all child datasets, new data is written to new blocks, but the old blocks are not reclaimed as free space. The snapshot contains the original version of the file system, and the live file system contains any changes made since the snapshot was taken. No additional space is used. As new data is written to the live file system, new blocks are allocated to store this data. The apparent size of the snapshot will grow as the blocks are no longer used in the live file system, but only in the snapshot. These snapshots can be mounted read only to allow for the recovery of previous versions of files. It is also possible to <<zfs-zfs-snapshot,rollback>> a live file system to a specific snapshot, undoing any changes that took place after the snapshot was taken. Each block in the pool has a reference counter which keeps track of how many snapshots, clones, datasets, or volumes make use of that block. As files and snapshots are deleted, the reference count is decremented. When a block is no longer referenced, it is reclaimed as free space. Snapshots can also be marked with a <<zfs-zfs-snapshot,hold>>. When a snapshot is held, any attempt to destroy it will return an `EBUSY` error. Each snapshot can have multiple holds, each with a unique name. The <<zfs-zfs-snapshot,release>> command removes the hold so the snapshot can deleted. Snapshots can be taken on volumes, but they can only be cloned or rolled back, not mounted independently.
 
 |[[zfs-term-clone]]Clone
 |Snapshots can also be cloned. A clone is a writable version of a snapshot, allowing the file system to be forked as a new dataset. As with a snapshot, a clone initially consumes no additional space. As new data is written to a clone and new blocks are allocated, the apparent size of the clone grows. When blocks are overwritten in the cloned file system or volume, the reference count on the previous block is decremented. The snapshot upon which a clone is based cannot be deleted because the clone depends on it. The snapshot is the parent, and the clone is the child. Clones can be _promoted_, reversing this dependency and making the clone the parent and the previous parent the child. This operation requires no additional space. Since the amount of space used by the parent and child is reversed, existing quotas and reservations might be affected.
 
 |[[zfs-term-checksum]]Checksum
 |Every block that is allocated is also checksummed. The checksum algorithm used is a per-dataset property, see <<zfs-zfs-set,`set`>>. The checksum of each block is transparently validated as it is read, allowing ZFS to detect silent corruption. If the data that is read does not match the expected checksum, ZFS will attempt to recover the data from any available redundancy, like mirrors or RAID-Z. Validation of all checksums can be triggered with <<zfs-term-scrub,`scrub`>>. Checksum algorithms include:
 
 * `fletcher2`
 * `fletcher4`
 * `sha256`
  The `fletcher` algorithms are faster, but `sha256` is a strong cryptographic hash and has a much lower chance of collisions at the cost of some performance. Checksums can be disabled, but it is not recommended.
 
 |[[zfs-term-compression]]Compression
 |Each dataset has a compression property, which defaults to off. This property can be set to one of a number of compression algorithms. This will cause all new data that is written to the dataset to be compressed. Beyond a reduction in space used, read and write throughput often increases because fewer blocks are read or written. 
 
 [[zfs-term-compression-lz4]]
 * _LZ4_ - Added in ZFS pool version 5000 (feature flags), LZ4 is now the recommended compression algorithm. LZ4 compresses approximately 50% faster than LZJB when operating on compressible data, and is over three times faster when operating on uncompressible data. LZ4 also decompresses approximately 80% faster than LZJB. On modern CPUs, LZ4 can often compress at over 500 MB/s, and decompress at over 1.5 GB/s (per single CPU core).
 [[zfs-term-compression-lzjb]]
 * _LZJB_ - The default compression algorithm. Created by Jeff Bonwick (one of the original creators of ZFS). LZJB offers good compression with less CPU overhead compared to GZIP. In the future, the default compression algorithm will likely change to LZ4.
 [[zfs-term-compression-gzip]]
 * _GZIP_ - A popular stream compression algorithm available in ZFS. One of the main advantages of using GZIP is its configurable level of compression. When setting the `compress` property, the administrator can choose the level of compression, ranging from `gzip1`, the lowest level of compression, to `gzip9`, the highest level of compression. This gives the administrator control over how much CPU time to trade for saved disk space.
 [[zfs-term-compression-zle]]
 * _ZLE_ - Zero Length Encoding is a special compression algorithm that only compresses continuous runs of zeros. This compression algorithm is only useful when the dataset contains large blocks of zeros.
 
 |[[zfs-term-copies]]Copies
 |When set to a value greater than 1, the `copies` property instructs ZFS to maintain multiple copies of each block in the <<zfs-term-filesystem,File System>> or <<zfs-term-volume,Volume>>. Setting this property on important datasets provides additional redundancy from which to recover a block that does not match its checksum. In pools without redundancy, the copies feature is the only form of redundancy. The copies feature can recover from a single bad sector or other forms of minor corruption, but it does not protect the pool from the loss of an entire disk.
 
 |[[zfs-term-deduplication]]Deduplication
 |Checksums make it possible to detect duplicate blocks of data as they are written. With deduplication, the reference count of an existing, identical block is increased, saving storage space. To detect duplicate blocks, a deduplication table (DDT) is kept in memory. The table contains a list of unique checksums, the location of those blocks, and a reference count. When new data is written, the checksum is calculated and compared to the list. If a match is found, the existing block is used. The SHA256 checksum algorithm is used with deduplication to provide a secure cryptographic hash. Deduplication is tunable. If `dedup` is `on`, then a matching checksum is assumed to mean that the data is identical. If `dedup` is set to `verify`, then the data in the two blocks will be checked byte-for-byte to ensure it is actually identical. If the data is not identical, the hash collision will be noted and the two blocks will be stored separately. As DDT must store the hash of each unique block, it consumes a very large amount of memory. A general rule of thumb is 5-6 GB of ram per 1 TB of deduplicated data). In situations where it is not practical to have enough RAM to keep the entire DDT in memory, performance will suffer greatly as the DDT must be read from disk before each new block is written. Deduplication can use L2ARC to store the DDT, providing a middle ground between fast system memory and slower disks. Consider using compression instead, which often provides nearly as much space savings without the additional memory requirement.
 
 |[[zfs-term-scrub]]Scrub
 |Instead of a consistency check like man:fsck[8], ZFS has `scrub`. `scrub` reads all data blocks stored on the pool and verifies their checksums against the known good checksums stored in the metadata. A periodic check of all the data stored on the pool ensures the recovery of any corrupted blocks before they are needed. A scrub is not required after an unclean shutdown, but is recommended at least once every three months. The checksum of each block is verified as blocks are read during normal use, but a scrub makes certain that even infrequently used blocks are checked for silent corruption. Data security is improved, especially in archival storage situations. The relative priority of `scrub` can be adjusted with <<zfs-advanced-tuning-scrub_delay,`vfs.zfs.scrub_delay`>> to prevent the scrub from degrading the performance of other workloads on the pool.
 
 |[[zfs-term-quota]]Dataset Quota
 a|ZFS provides very fast and accurate dataset, user, and group space accounting in addition to quotas and space reservations. This gives the administrator fine grained control over how space is allocated and allows space to be reserved for critical file systems. 
 
 ZFS supports different types of quotas: the dataset quota, the <<zfs-term-refquota,reference quota (refquota)>>, the <<zfs-term-userquota,user quota>>, and the <<zfs-term-groupquota,group quota>>.
 
 Quotas limit the amount of space that a dataset and all of its descendants, including snapshots of the dataset, child datasets, and the snapshots of those datasets, can consume.
 
 [NOTE]
 ====
 Quotas cannot be set on volumes, as the `volsize` property acts as an implicit quota.
 ====
 
 |[[zfs-term-refquota]]Reference Quota
 |A reference quota limits the amount of space a dataset can consume by enforcing a hard limit. However, this hard limit includes only space that the dataset references and does not include space used by descendants, such as file systems or snapshots.
 
 |[[zfs-term-userquota]]User Quota
 |User quotas are useful to limit the amount of space that can be used by the specified user.
 
 |[[zfs-term-groupquota]]Group Quota
 |The group quota limits the amount of space that a specified group can consume.
 
 |[[zfs-term-reservation]]Dataset Reservation
 |The `reservation` property makes it possible to guarantee a minimum amount of space for a specific dataset and its descendants. If a 10 GB reservation is set on [.filename]#storage/home/bob#, and another dataset tries to use all of the free space, at least 10 GB of space is reserved for this dataset. If a snapshot is taken of [.filename]#storage/home/bob#, the space used by that snapshot is counted against the reservation. The <<zfs-term-refreservation,`refreservation`>> property works in a similar way, but it _excludes_ descendants like snapshots. 
 
 Reservations of any sort are useful in many situations, such as planning and testing the suitability of disk space allocation in a new system, or ensuring that enough space is available on file systems for audio logs or system recovery procedures and files.
 
 |[[zfs-term-refreservation]]Reference Reservation
 |The `refreservation` property makes it possible to guarantee a minimum amount of space for the use of a specific dataset _excluding_ its descendants. This means that if a 10 GB reservation is set on [.filename]#storage/home/bob#, and another dataset tries to use all of the free space, at least 10 GB of space is reserved for this dataset. In contrast to a regular <<zfs-term-reservation,reservation>>, space used by snapshots and descendant datasets is not counted against the reservation. For example, if a snapshot is taken of [.filename]#storage/home/bob#, enough disk space must exist outside of the `refreservation` amount for the operation to succeed. Descendants of the main data set are not counted in the `refreservation` amount and so do not encroach on the space set.
 
 |[[zfs-term-resilver]]Resilver
 |When a disk fails and is replaced, the new disk must be filled with the data that was lost. The process of using the parity information distributed across the remaining drives to calculate and write the missing data to the new drive is called _resilvering_.
 
 |[[zfs-term-online]]Online
 |A pool or vdev in the `Online` state has all of its member devices connected and fully operational. Individual devices in the `Online` state are functioning normally.
 
 |[[zfs-term-offline]]Offline
 |Individual devices can be put in an `Offline` state by the administrator if there is sufficient redundancy to avoid putting the pool or vdev into a <<zfs-term-faulted,Faulted>> state. An administrator may choose to offline a disk in preparation for replacing it, or to make it easier to identify.
 
 |[[zfs-term-degraded]]Degraded
 |A pool or vdev in the `Degraded` state has one or more disks that have been disconnected or have failed. The pool is still usable, but if additional devices fail, the pool could become unrecoverable. Reconnecting the missing devices or replacing the failed disks will return the pool to an <<zfs-term-online,Online>> state after the reconnected or new device has completed the <<zfs-term-resilver,Resilver>> process.
 
 |[[zfs-term-faulted]]Faulted
 |A pool or vdev in the `Faulted` state is no longer operational. The data on it can no longer be accessed. A pool or vdev enters the `Faulted` state when the number of missing or failed devices exceeds the level of redundancy in the vdev. If missing devices can be reconnected, the pool will return to an <<zfs-term-online,Online>> state. If there is insufficient redundancy to compensate for the number of failed disks, then the contents of the pool are lost and must be restored from backups.
 |===
diff --git a/documentation/content/en/books/porters-handbook/makefiles/_index.adoc b/documentation/content/en/books/porters-handbook/makefiles/_index.adoc
index ddf8d9e63a..60c878dbac 100644
--- a/documentation/content/en/books/porters-handbook/makefiles/_index.adoc
+++ b/documentation/content/en/books/porters-handbook/makefiles/_index.adoc
@@ -1,4866 +1,4866 @@
 ---
 title: Chapter 5. Configuring the Makefile
 prev: books/porters-handbook/slow-porting
 next: books/porters-handbook/special
 description: Configuring the Makefile for FreeBSD Ports
 tags: ["makefiles", "configuring", "naming", "versions"]
 ---
 
 [[makefiles]]
 = Configuring the Makefile
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 5
 :g-plus-plus: g++
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 Configuring the [.filename]#Makefile# is pretty simple, and again we suggest looking at existing examples before starting. Also, there is a crossref:porting-samplem[porting-samplem,sample Makefile] in this handbook, so take a look and please follow the ordering of variables and sections in that template to make the port easier for others to read.
 
 Consider these problems in sequence during the design of the new [.filename]#Makefile#:
 
 [[makefile-source]]
 == The Original Source
 
 Does it live in `DISTDIR` as a standard ``gzip``ped tarball named something like [.filename]#foozolix-1.2.tar.gz#? If so, go on to the next step. If not, the distribution file format might require overriding one or more of `DISTVERSION`, `DISTNAME`, `EXTRACT_CMD`, `EXTRACT_BEFORE_ARGS`, `EXTRACT_AFTER_ARGS`, `EXTRACT_SUFX`, or `DISTFILES`.
 
 In the worst case, create a custom `do-extract` target to override the default. This is rarely, if ever, necessary.
 
 [[makefile-naming]]
 == Naming
 
 The first part of the port's [.filename]#Makefile# names the port, describes its version number, and lists it in the correct category.
 
 [[makefile-portname]]
 === `PORTNAME`
 
 Set `PORTNAME` to the base name of the software. It is used as the base for the FreeBSD package, and for <<makefile-distname,`DISTNAME`>>.
 
 [IMPORTANT]
 ====
 The package name must be unique across the entire ports tree. Make sure that the `PORTNAME` is not already in use by an existing port, and that no other port already has the same `PKGBASE`. If the name has already been used, add either <<porting-pkgnameprefix-suffix,`PKGNAMEPREFIX` or `PKGNAMESUFFIX`>>.
 ====
 
 [[makefile-versions]]
 === Versions, `DISTVERSION` _or_ `PORTVERSION`
 
 Set `DISTVERSION` to the version number of the software.
 
 `PORTVERSION` is the version used for the FreeBSD package. It will be automatically derived from `DISTVERSION` to be compatible with FreeBSD's package versioning scheme. If the version contains _letters_, it might be needed to set `PORTVERSION` and not `DISTVERSION`.
 
 [IMPORTANT]
 ====
 Only one of `PORTVERSION` and `DISTVERSION` can be set at a time.
 ====
 
 From time to time, some software will use a version scheme that is not compatible with how `DISTVERSION` translates in `PORTVERSION`.
 
 [TIP]
 ====
 
 When updating a port, it is possible to use man:pkg-version[8]'s `-t` argument to check if the new version is greater or lesser than before. See <<makefile-versions-ex-pkg-version>>.
 ====
 
 [[makefile-versions-ex-pkg-version]]
 .Using man:pkg-version[8] to Compare Versions
 [example]
 ====
 `pkg version -t` takes two versions as arguments, it will respond with `<`, `=` or `>` if the first version is less, equal, or more than the second version, respectively.
 
 [source,shell]
 ....
 % pkg version -t 1.2 1.3
 < <.>
 % pkg version -t 1.2 1.2
 = <.>
 % pkg version -t 1.2 1.2.0
 = <.>
 % pkg version -t 1.2 1.2.p1
 > <.>
 % pkg version -t 1.2.a1 1.2.b1
 < <.>
 % pkg version -t 1.2 1.2p1
 < <.>
 ....
 
 <.> `1.2` is before `1.3`.
 <.> `1.2` and `1.2` are equal as they have the same version.
 <.> `1.2` and `1.2.0` are equal as nothing equals zero.
 <.> `1.2` is after `1.2.p1` as `.p1`, think "pre-release 1".
 <.> `1.2.a1` is before `1.2.b1`, think "alpha" and "beta", and `a` is before `b`.
 <.> `1.2` is before `1.2p1` as `2p1`, think "2, patch level 1" which is a version after any `2.X` but before `3`.
 
 [NOTE]
 ****
 In here, the `a`, `b`, and `p` are used as if meaning "alpha", "beta" or "pre-release" and "patch level", but they are only letters and are sorted alphabetically, so any letter can be used, and they will be sorted appropriately.
 ****
 
 ====
 
 .Examples of `DISTVERSION` and the Derived `PORTVERSION`
 [cols="10%,90%", frame="none", options="header"]
 |===
 | DISTVERSION
 | PORTVERSION
 
 |0.7.1d
 |0.7.1.d
 
 |10Alpha3
 |10.a3
 
 |3Beta7-pre2
 |3.b7.p2
 
 |8:f_17
 |8f.17
 |===
 
 [[makefile-versions-ex1]]
 .Using `DISTVERSION`
 [example]
 ====
 When the version only contains numbers separated by dots, dashes or underscores, use `DISTVERSION`.
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSION=	1.2-4
 ....
 
 It will generate a `PORTVERSION` of `1.2.4`.
 ====
 
 [[makefile-versions-ex2]]
 .Using `DISTVERSION` When the Version Starts with a Letter or a Prefix
 [example]
 ====
 When the version starts or ends with a letter, or a prefix or a suffix that is not part of the version, use `DISTVERSIONPREFIX`, `DISTVERSION`, and `DISTVERSIONSUFFIX`.
 
 If the version is `v1.2-4`:
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSIONPREFIX=  v
 DISTVERSION=	1_2_4
 ....
 
 Some of the time, projects using GitHub will use their name in their versions. For example, the version could be `nekoto-1.2-4`:
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSIONPREFIX=  nekoto-
 DISTVERSION=	1.2_4
 ....
 
 Those projects also sometimes use some string at the end of the version, for example, `1.2-4_RELEASE`:
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSION=	1.2-4
 DISTVERSIONSUFFIX=  _RELEASE
 ....
 
 Or they do both, for example, `nekoto-1.2-4_RELEASE`:
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSIONPREFIX=  nekoto-
 DISTVERSION=	1.2-4
 DISTVERSIONSUFFIX=  _RELEASE
 ....
 
 `DISTVERSIONPREFIX` and `DISTVERSIONSUFFIX` will not be used while constructing `PORTVERSION`, but only used in `DISTNAME`.
 
 All will generate a `PORTVERSION` of `1.2.4`.
 ====
 
 [[makefile-versions-ex3]]
 .Using `DISTVERSION` When the Version Contains Letters Meaning "alpha", "beta", or "pre-release"
 [example]
 ====
 When the version contains numbers separated by dots, dashes or underscores, and letters are used to mean "alpha", "beta" or "pre-release", which is, before the version without the letters, use `DISTVERSION`.
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSION=	1.2-pre4
 ....
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 DISTVERSION=	1.2p4
 ....
 
 Both will generate a `PORTVERSION` of `1.2.p4` which is before than 1.2. man:pkg-version[8] can be used to check that fact:
 
 [source,shell]
 ....
 % pkg version -t 1.2.p4 1.2
 <
 ....
 
 ====
 
 [[makefile-versions-ex4]]
 .Not Using `DISTVERSION` When the Version Contains Letters Meaning "Patch Level"
 [example]
 ====
 When the version contains letters that are not meant as "alpha", "beta", or "pre", but more in a "patch level", and meaning after the version without the letters, use `PORTVERSION`.
 
 [.programlisting]
 ....
 PORTNAME=   nekoto
 PORTVERSION=	1.2p4
 ....
 
 In this case, using `DISTVERSION` is not possible because it would generate a version of `1.2.p4` which would be before `1.2` and not after. man:pkg-version[8] will verify this:
 
 [source,shell]
 ....
 % pkg version -t 1.2 1.2.p4
 > <.>
 % pkg version -t 1.2 1.2p4
 < <.>
 ....
 
 <.> `1.2` is after `1.2.p4`, which is _wrong_ in this case.
 <.> `1.2` is before `1.2p4`, which is what was needed.
 ====
 
 For some more advanced examples of setting `PORTVERSION`, when the software's versioning is really not compatible with FreeBSD's, or `DISTNAME` when the distribution file does not contain the version itself, see <<makefile-distname>>.
 
 [[makefile-naming-revepoch]]
 === `PORTREVISION` and `PORTEPOCH`
 
 [[makefile-portrevision]]
 ==== `PORTREVISION`
 
 `PORTREVISION` is a monotonically increasing value which is reset to 0 with every increase of `DISTVERSION`, typically every time there is a new official vendor release. If `PORTREVISION` is non-zero, the value is appended to the package name. Changes to `PORTREVISION` are used by automated tools like man:pkg-version[8] to determine that a new package is available.
 
 `PORTREVISION` must be increased each time a change is made to the port that changes the generated package in any way. That includes changes that only affect a package built with non-default <<makefile-options,options>>.
 
 Examples of when `PORTREVISION` must be bumped:
 
 * Addition of patches to correct security vulnerabilities, bugs, or to add new functionality to the port.
 * Changes to the port [.filename]#Makefile# to enable or disable compile-time options in the package.
 * Changes in the packing list or the install-time behavior of the package. For example, a change to a script which generates initial data for the package, like man:ssh[1] host keys.
 * Version bump of a port's shared library dependency (in this case, someone trying to install the old package after installing a newer version of the dependency will fail since it will look for the old libfoo.x instead of libfoo.(x+1)).
 * Silent changes to the port distfile which have significant functional differences. For example, changes to the distfile requiring a correction to [.filename]#distinfo# with no corresponding change to `DISTVERSION`, where a `diff -ru` of the old and new versions shows non-trivial changes to the code.
 
 Examples of changes which do not require a `PORTREVISION` bump:
 
 * Style changes to the port skeleton with no functional change to what appears in the resulting package.
 * Changes to `MASTER_SITES` or other functional changes to the port which do not affect the resulting package.
 * Trivial patches to the distfile such as correction of typos, which are not important enough that users of the package have to go to the trouble of upgrading.
 * Build fixes which cause a package to become compilable where it was previously failing. As long as the changes do not introduce any functional change on any other platforms on which the port did previously build. Since `PORTREVISION` reflects the content of the package, if the package was not previously buildable then there is no need to increase `PORTREVISION` to mark a change.
 
 A rule of thumb is to decide whether a change committed to a port is something which _some_ people would benefit from having. Either because of an enhancement, fix, or by virtue that the new package will actually work at all. Then weigh that against that fact that it will cause everyone who regularly updates their ports tree to be compelled to update. If yes, `PORTREVISION` must be bumped.
 
 [NOTE]
 ====
 People using binary packages will _never_ see the update if `PORTREVISION` is not bumped. Without increasing `PORTREVISION`, the package builders have no way to detect the change and thus, will not rebuild the package.
 ====
 
 [[makefile-portepoch]]
 ==== `PORTEPOCH`
 
 From time to time a software vendor or FreeBSD porter will do something silly and release a version of their software which is actually numerically less than the previous version. An example of this is a port which goes from foo-20000801 to foo-1.0 (the former will be incorrectly treated as a newer version since 20000801 is a numerically greater value than 1).
 
 [TIP]
 ====
 
 The results of version number comparisons are not always obvious. `pkg version` (see man:pkg-version[8]) can be used to test the comparison of two version number strings. For example:
 
 [source,shell]
 ....
 % pkg version -t 0.031 0.29
 >
 ....
 
 The `>` output indicates that version 0.031 is considered greater than version 0.29, which may not have been obvious to the porter.
 ====
 
 In situations such as this, `PORTEPOCH` must be increased. If `PORTEPOCH` is nonzero it is appended to the package name as described in section 0 above. `PORTEPOCH` must never be decreased or reset to zero, because that would cause comparison to a package from an earlier epoch to fail. For example, the package would not be detected as out of date. The new version number, `1.0,1` in the above example, is still numerically less than the previous version, 20000801, but the `,1` suffix is treated specially by automated tools and found to be greater than the implied suffix `,0` on the earlier package.
 
 Dropping or resetting `PORTEPOCH` incorrectly leads to no end of grief. If the discussion above was not clear enough, please consult the {freebsd-ports}.
 
 It is expected that `PORTEPOCH` will not be used for the majority of ports, and that sensible use of `DISTVERSION`, or that use `PORTVERSION` carefully, can often preempt it becoming necessary if a future release of the software changes the version structure. However, care is needed by FreeBSD porters when a vendor release is made without an official version number - such as a code "snapshot" release. The temptation is to label the release with the release date, which will cause problems as in the example above when a new "official" release is made.
 
 For example, if a snapshot release is made on the date `20000917`, and the previous version of the software was version `1.2`, do not use `20000917` for `DISTVERSION`. The correct way is a `DISTVERSION` of `1.2.20000917`, or similar, so that the succeeding release, say `1.3`, is still a numerically greater value.
 
 [[makefile-portrevision-example]]
 ==== Example of `PORTREVISION` and `PORTEPOCH` Usage
 
 The `gtkmumble` port, version `0.10`, is committed to the ports collection:
 
 [.programlisting]
 ....
 PORTNAME=	gtkmumble
 DISTVERSION=	0.10
 ....
 
 `PKGNAME` becomes `gtkmumble-0.10`.
 
 A security hole is discovered which requires a local FreeBSD patch. `PORTREVISION` is bumped accordingly.
 
 [.programlisting]
 ....
 PORTNAME=	gtkmumble
 DISTVERSION=	0.10
 PORTREVISION=	1
 ....
 
 `PKGNAME` becomes `gtkmumble-0.10_1`
 
 A new version is released by the vendor, numbered `0.2` (it turns out the author actually intended `0.10` to actually mean `0.1.0`, not "what comes after 0.9" - oops, too late now). Since the new minor version `2` is numerically less than the previous version `10`, `PORTEPOCH` must be bumped to manually force the new package to be detected as "newer". Since it is a new vendor release of the code, `PORTREVISION` is reset to 0 (or removed from the [.filename]#Makefile#).
 
 [.programlisting]
 ....
 PORTNAME=	gtkmumble
 DISTVERSION=	0.2
 PORTEPOCH=	1
 ....
 
 `PKGNAME` becomes `gtkmumble-0.2,1`
 
 The next release is 0.3. Since `PORTEPOCH` never decreases, the version variables are now:
 
 [.programlisting]
 ....
 PORTNAME=	gtkmumble
 DISTVERSION=	0.3
 PORTEPOCH=	1
 ....
 
 `PKGNAME` becomes `gtkmumble-0.3,1`
 
 [NOTE]
 ====
 If `PORTEPOCH` were reset to `0` with this upgrade, someone who had installed the `gtkmumble-0.10_1` package would not detect the `gtkmumble-0.3` package as newer, since `3` is still numerically less than `10`. Remember, this is the whole point of `PORTEPOCH` in the first place.
 ====
 
 [[porting-pkgnameprefix-suffix]]
 === `PKGNAMEPREFIX` and `PKGNAMESUFFIX`
 
 Two optional variables, `PKGNAMEPREFIX` and `PKGNAMESUFFIX`, are combined with `PORTNAME` and `PORTVERSION` to form `PKGNAME` as `${PKGNAMEPREFIX}${PORTNAME}${PKGNAMESUFFIX}-${PORTVERSION}`. Make sure this conforms to our <<porting-pkgname,guidelines for a good package name>>. In particular, the use of a hyphen (`-`) in `PORTVERSION` is _not_ allowed. Also, if the package name has the _language-_ or the _-compiled.specifics_ part (see below), use `PKGNAMEPREFIX` and `PKGNAMESUFFIX`, respectively. Do not make them part of `PORTNAME`.
 
 [[porting-pkgname]]
 === Package Naming Conventions
 
 These are the conventions to follow when naming packages. This is to make the package directory easy to scan, as there are already thousands of packages and users are going to turn away if they hurt their eyes!
 
 Package names take the form of [.filename]#language_region-name-compiled.specifics-version.numbers#.
 
 The package name is defined as `${PKGNAMEPREFIX}${PORTNAME}${PKGNAMESUFFIX}-${PORTVERSION}`. Make sure to set the variables to conform to that format.
 
 [[porting-pkgname-language]]
 [.filename]#language_region-#::
 FreeBSD strives to support the native language of its users. The _language-_ part is a two letter abbreviation of the natural language defined by ISO-639 when the port is specific to a certain language. Examples are `ja` for Japanese, `ru` for Russian, `vi` for Vietnamese, `zh` for Chinese, `ko` for Korean and `de` for German.
 +
 If the port is specific to a certain region within the language area, add the two letter country code as well. Examples are `en_US` for US English and `fr_CH` for Swiss French.
 +
 The _language-_ part is set in `PKGNAMEPREFIX`.
 
 [[porting-pkgname-name]]
 [.filename]#name#::
 Make sure that the port's name and version are clearly separated and placed into `PORTNAME` and `DISTVERSION`. The only reason for `PORTNAME` to contain a version part is if the upstream distribution is really named that way, as in the package:textproc/libxml2[] or package:japanese/kinput2-freewnn[] ports. Otherwise, `PORTNAME` cannot contain any version-specific information. It is quite normal for several ports to have the same `PORTNAME`, as the package:www/apache*[] ports do; in that case, different versions (and different index entries) are distinguished by `PKGNAMEPREFIX` and `PKGNAMESUFFIX` values.
 +
 There is a tradition of naming `Perl 5` modules by prepending `p5-` and converting the double-colon separator to a hyphen. For example, the `Data::Dumper` module becomes `p5-Data-Dumper`.
 [[porting-pkgname-compiled-specifics]]
 [.filename]#-compiled.specifics#::
 If the port can be built with different <<makefile-masterdir,hardcoded defaults>> (usually part of the directory name in a family of ports), the _-compiled.specifics_ part states the compiled-in defaults. The hyphen is optional. Examples are paper size and font units.
 +
 The _-compiled.specifics_ part is set in `PKGNAMESUFFIX`.
 
 [[porting-pkgname-version-numbers]]
 [.filename]#-version.numbers#::
 The version string follows a dash (`-`) and is a period-separated list of integers and single lowercase alphabetics. In particular, it is not permissible to have another dash inside the version string. The only exception is the string `pl` (meaning "patchlevel"), which can be used _only_ when there are no major and minor version numbers in the software. If the software version has strings like "alpha", "beta", "rc", or "pre", take the first letter and put it immediately after a period. If the version string continues after those names, the numbers follow the single alphabet without an extra period between them (for example, `1.0b2`).
 +
 The idea is to make it easier to sort ports by looking at the version string. In particular, make sure version number components are always delimited by a period, and if the date is part of the string, use the `d__yyyy.mm.dd__` format, not `_dd.mm.yyyy_` or the non-Y2K compliant `_yy.mm.dd_` format. It is important to prefix the version with a letter, here `d` (for date), in case a release with an actual version number is made, which would be numerically less than `_yyyy_`.
 
 [IMPORTANT]
 ====
 Package name must be unique among all of the ports tree, check that there is not already a port with the same `PORTNAME` and if there is add one of <<porting-pkgnameprefix-suffix,`PKGNAMEPREFIX` or `PKGNAMESUFFIX`>>.
 ====
 
 Here are some (real) examples on how to convert the name as called by the software authors to a suitable package name, for each line, only one of `DISTVERSION` or `PORTVERSION` is set in, depending on which would be used in the port's [.filename]#Makefile#:
 
 .Package Naming Examples
 [cols="1,1,1,1,1,1,1", frame="none", options="header"]
 |===
 | Distribution Name
 | PKGNAMEPREFIX
 | PORTNAME
 | PKGNAMESUFFIX
 | DISTVERSION
 | PORTVERSION
 | Reason or comment
 
 |mule-2.2.2
 |(empty)
 |mule
 |(empty)
 |2.2.2
 |
 |No changes required
 
 |mule-1.0.1
 |(empty)
 |mule
 |1
 |1.0.1
 |
 |This is version 1 of mule, and version 2 already exists
 
 |EmiClock-1.0.2
 |(empty)
 |emiclock
 |(empty)
 |1.0.2
 |
 |No uppercase names for single programs
 
 |rdist-1.3alpha
 |(empty)
 |rdist
 |(empty)
 |1.3alpha
 |
 |Version will be `1.3.a`
 
 |es-0.9-beta1
 |(empty)
 |es
 |(empty)
 |0.9-beta1
 |
 |Version will be `0.9.b1`
 
 |mailman-2.0rc3
 |(empty)
 |mailman
 |(empty)
 |2.0rc3
 |
 |Version will be `2.0.r3`
 
 |v3.3beta021.src
 |(empty)
 |tiff
 |(empty)
 |
 |3.3
 |What the heck was that anyway?
 
 |tvtwm
 |(empty)
 |tvtwm
 |(empty)
 |
 |p11
 |No version in the filename, use what upstream says it is
 
 |piewm
 |(empty)
 |piewm
 |(empty)
 |1.0
 |
 |No version in the filename, use what upstream says it is
 
 |xvgr-2.10pl1
 |(empty)
 |xvgr
 |(empty)
 |
 |2.10.pl1
 |In that case, `pl1` means patch level, so using DISTVERSION is not possible.
 
 |gawk-2.15.6
 |ja-
 |gawk
 |(empty)
 |2.15.6
 |
 |Japanese language version
 
 |psutils-1.13
 |(empty)
 |psutils
 |-letter
 |1.13
 |
 |Paper size hardcoded at package build time
 
 |pkfonts
 |(empty)
 |pkfonts
 |300
 |1.0
 |
 |Package for 300dpi fonts
 |===
 
 If there is absolutely no trace of version information in the original source and it is unlikely that the original author will ever release another version, just set the version string to `1.0` (like the `piewm` example above). Otherwise, ask the original author or use the date string the source file was released on (`d__yyyy.mm.dd__`, or `d__yyyymmdd__`) as the version.
 
 [TIP]
 ====
 
 Use any letter. Here, `d` here stands for date, if the source is a Git repository, `g` followed by the commit date is commonly used, using `s` for snapshot is also common.
 ====
 
 [[makefile-categories]]
 == Categorization
 
 [[makefile-categories-definition]]
 === `CATEGORIES`
 
 When a package is created, it is put under [.filename]#/usr/ports/packages/All# and links are made from one or more subdirectories of [.filename]#/usr/ports/packages#. The names of these subdirectories are specified by the variable `CATEGORIES`. It is intended to make life easier for the user when he is wading through the pile of packages on the FTP site or the CDROM. Please take a look at the <<porting-categories,current list of categories>> and pick the ones that are suitable for the port.
 
 This list also determines where in the ports tree the port is imported. If there is more than one category here, the port files must be put in the subdirectory with the name of the first category. See <<choosing-categories,below>> for more discussion about how to pick the right categories.
 
 [[porting-categories]]
 === Current List of Categories
 
 Here is the current list of port categories. Those marked with an asterisk (`*`) are _virtual_ categories-those that do not have a corresponding subdirectory in the ports tree. They are only used as secondary categories, and only for search purposes.
 
 [NOTE]
 ====
 For non-virtual categories, there is a one-line description in `COMMENT` in that subdirectory's [.filename]#Makefile#.
 ====
 
 [.informaltable]
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Category
 | Description
 | Notes
 
 |[.filename]#accessibility#
 |Ports to help disabled users.
 |
 
 |[.filename]#afterstep#`*`
 |Ports to support the http://www.afterstep.org[AfterStep] window manager.
 |
 
 |[.filename]#arabic#
 |Arabic language support.
 |
 
 |[.filename]#archivers#
 |Archiving tools.
 |
 
 |[.filename]#astro#
 |Astronomical ports.
 |
 
 |[.filename]#audio#
 |Sound support.
 |
 
 |[.filename]#benchmarks#
 |Benchmarking utilities.
 |
 
 |[.filename]#biology#
 |Biology-related software.
 |
 
 |[.filename]#cad#
 |Computer aided design tools.
 |
 
 |[.filename]#chinese#
 |Chinese language support.
 |
 
 |[.filename]#comms#
 |Communication software.
 |Mostly software to talk to the serial port.
 
 |[.filename]#converters#
 |Character code converters.
 |
 
 |[.filename]#databases#
 |Databases.
 |
 
 |[.filename]#deskutils#
 |Things that used to be on the desktop before computers were invented.
 |
 
 |[.filename]#devel#
 |Development utilities.
 |Do not put libraries here just because they are libraries. They should _not_ be in this category unless they truly do not belong anywhere else.
 
 |[.filename]#dns#
 |DNS-related software.
 |
 
 |[.filename]#docs#`*`
 |Meta-ports for FreeBSD documentation.
 |
 
 |[.filename]#editors#
 |General editors.
 |Specialized editors go in the section for those tools. For example, a mathematical-formula editor will go in [.filename]#math#, and have [.filename]#editors# as a second category.
 
 |[.filename]#education#`*`
 |Education-related software.
 |This includes applications, utilities, or games primarily or substantially designed to help the user learn a specific topic or study in general. It also includes course-writing applications, course-delivery applications, and classroom or school management applications
 
 |[.filename]#elisp#`*`
 |Emacs-lisp ports.
 |
 
 |[.filename]#emulators#
 |Emulators for other operating systems.
 |Terminal emulators do _not_ belong here. X-based ones go to [.filename]#x11# and text-based ones to either [.filename]#comms# or [.filename]#misc#, depending on the exact functionality.
 
 |[.filename]#enlightenment#`*`
 |Ports related to the Enlightenment window manager.
 |
 
 |[.filename]#finance#
 |Monetary, financial and related applications.
 |
 
 |[.filename]#french#
 |French language support.
 |
 
 |[.filename]#ftp#
 |FTP client and server utilities.
 |If the port speaks both FTP and HTTP, put it in [.filename]#ftp# with a secondary category of [.filename]#www#.
 
 |[.filename]#games#
 |Games.
 |
 
 |[.filename]#geography#`*`
 |Geography-related software.
 |
 
 |[.filename]#german#
 |German language support.
 |
 
 |[.filename]#gnome#`*`
 |Ports from the http://www.gnome.org[GNOME] Project.
 |
 
 |[.filename]#gnustep#`*`
 |Software related to the GNUstep desktop environment.
 |
 
 |[.filename]#graphics#
 |Graphics utilities.
 |
 
 |[.filename]#hamradio#`*`
 |Software for amateur radio.
 |
 
 |[.filename]#haskell#`*`
 |Software related to the Haskell language.
 |
 
 |[.filename]#hebrew#
 |Hebrew language support.
 |
 
 |[.filename]#hungarian#
 |Hungarian language support.
 |
 
 |[.filename]#irc#
 |Internet Relay Chat utilities.
 |
 
 |[.filename]#japanese#
 |Japanese language support.
 |
 
 |[.filename]#java#
 |Software related to the Java(TM) language.
 |The [.filename]#java# category must not be the only one for a port. Save for ports directly related to the Java language, porters are also encouraged not to use [.filename]#java# as the main category of a port.
 
 |[.filename]#kde#`*`
 |Ports from the http://www.kde.org[KDE] Project (generic).
 |
 
 |[.filename]#kde-applications#`*`
 |Applications from the http://www.kde.org[KDE] Project.
 |
 
 |[.filename]#kde-frameworks#`*`
 |Add-on libraries from the http://www.kde.org[KDE] Project for programming with Qt.
 |
 
 |[.filename]#kde-plasma#`*`
 |Desktop from the http://www.kde.org[KDE] Project.
 |
 
 |[.filename]#kld#`*`
 |Kernel loadable modules.
 |
 
 |[.filename]#korean#
 |Korean language support.
 |
 
 |[.filename]#lang#
 |Programming languages.
 |
 
 |[.filename]#linux#`*`
 |Linux applications and support utilities.
 |
 
 |[.filename]#lisp#`*`
 |Software related to the Lisp language.
 |
 
 |[.filename]#mail#
 |Mail software.
 |
 
 |[.filename]#mate#`*`
 |Ports related to the MATE desktop environment, a fork of GNOME 2.
 |
 
 |[.filename]#math#
 |Numerical computation software and other utilities for mathematics.
 |
 
 |[.filename]#mbone#`*`
 |MBone applications.
 |
 
 |[.filename]#misc#
 |Miscellaneous utilities
 |Things that do not belong anywhere else. If at all possible, try to find a better category for the port than `misc`, as ports tend to be overlooked in here.
 
 |[.filename]#multimedia#
 |Multimedia software.
 |
 
 |[.filename]#net#
 |Miscellaneous networking software.
 |
 
 |[.filename]#net-im#
 |Instant messaging software.
 |
 
 |[.filename]#net-mgmt#
 |Networking management software.
 |
 
 |[.filename]#net-p2p#
 |Peer to peer network applications.
 |
 
 |[.filename]#net-vpn#`*`
 |Virtual Private Network applications.
 |
 
 |[.filename]#news#
 |USENET news software.
 |
 
 |[.filename]#parallel#`*`
 |Applications dealing with parallelism in computing.
 |
 
 |[.filename]#pear#`*`
 |Ports related to the Pear PHP framework.
 |
 
 |[.filename]#perl5#`*`
 |Ports that require Perl version 5 to run.
 |
 
 |[.filename]#plan9#`*`
 |Various programs from http://www.cs.bell-labs.com/plan9dist/[Plan9].
 |
 
 |[.filename]#polish#
 |Polish language support.
 |
 
 |[.filename]#ports-mgmt#
 |Ports for managing, installing and developing FreeBSD ports and packages.
 |
 
 |[.filename]#portuguese#
 |Portuguese language support.
 |
 
 |[.filename]#print#
 |Printing software.
 |Desktop publishing tools (previewers, etc.) belong here too.
 
 |[.filename]#python#`*`
 |Software related to the http://www.python.org/[Python] language.
 |
 
 |[.filename]#ruby#`*`
 |Software related to the http://www.ruby-lang.org/[Ruby] language.
 |
 
 |[.filename]#rubygems#`*`
 |Ports of http://www.rubygems.org/[RubyGems] packages.
 |
 
 |[.filename]#russian#
 |Russian language support.
 |
 
 |[.filename]#scheme#`*`
 |Software related to the Scheme language.
 |
 
 |[.filename]#science#
 |Scientific ports that do not fit into other categories such as [.filename]#astro#, [.filename]#biology# and [.filename]#math#.
 |
 
 |[.filename]#security#
 |Security utilities.
 |
 
 |[.filename]#shells#
 |Command line shells.
 |
 
 |[.filename]#spanish#`*`
 |Spanish language support.
 |
 
 |[.filename]#sysutils#
 |System utilities.
 |
 
 |[.filename]#tcl#`*`
 |Ports that use Tcl to run.
 |
 
 |[.filename]#textproc#
 |Text processing utilities.
 |It does not include desktop publishing tools, which go to [.filename]#print#.
 
 |[.filename]#tk#`*`
 |Ports that use Tk to run.
 |
 
 |[.filename]#ukrainian#
 |Ukrainian language support.
 |
 
 |[.filename]#vietnamese#
 |Vietnamese language support.
 |
 
 |[.filename]#wayland#`*`
 |Ports to support the Wayland display server.
 |
 
 |[.filename]#windowmaker#`*`
 |Ports to support the Window Maker window manager.
 |
 
 |[.filename]#www#
 |Software related to the World Wide Web.
 |HTML language support belongs here too.
 
 |[.filename]#x11#
 |The X Window System and friends.
 |This category is only for software that directly supports the window system. Do not put regular X applications here. Most of them go into other [.filename]#x11-*# categories (see below).
 
 |[.filename]#x11-clocks#
 |X11 clocks.
 |
 
 |[.filename]#x11-drivers#
 |X11 drivers.
 |
 
 |[.filename]#x11-fm#
 |X11 file managers.
 |
 
 |[.filename]#x11-fonts#
 |X11 fonts and font utilities.
 |
 
 |[.filename]#x11-servers#
 |X11 servers.
 |
 
 |[.filename]#x11-themes#
 |X11 themes.
 |
 
 |[.filename]#x11-toolkits#
 |X11 toolkits.
 |
 
 |[.filename]#x11-wm#
 |X11 window managers.
 |
 
 |[.filename]#xfce#`*`
 |Ports related to the http://www.xfce.org/[Xfce] desktop environment.
 |
 
 |[.filename]#zope#`*`
 |http://www.zope.org/[Zope] support.
 |
 |===
 
 [[choosing-categories]]
 === Choosing the Right Category
 
 As many of the categories overlap, choosing which of the categories will be the primary category of the port can be tedious. There are several rules that govern this issue. Here is the list of priorities, in decreasing order of precedence:
 
 * The first category must be a physical category (see <<porting-categories,above>>). This is necessary to make the packaging work. Virtual categories and physical categories may be intermixed after that.
 * Language specific categories always come first. For example, if the port installs Japanese X11 fonts, then the `CATEGORIES` line would read [.filename]#japanese x11-fonts#.
 * Specific categories are listed before less-specific ones. For instance, an HTML editor is listed as [.filename]#www editors#, not the other way around. Also, do not list [.filename]#net# when the port belongs to any of [.filename]#irc#, [.filename]#mail#, [.filename]#news#, [.filename]#security#, or [.filename]#www#, as [.filename]#net# is included implicitly.
 * [.filename]#x11# is used as a secondary category only when the primary category is a natural language. In particular, do not put [.filename]#x11# in the category line for X applications.
 * Emacs modes are placed in the same ports category as the application supported by the mode, not in [.filename]#editors#. For example, an Emacs mode to edit source files of some programming language goes into [.filename]#lang#.
 * Ports installing loadable kernel modules also have the virtual category [.filename]#kld# in their `CATEGORIES` line. This is one of the things handled automatically by adding `USES=kmod`.
 * [.filename]#misc# does not appear with any other non-virtual category. If there is `misc` with something else in `CATEGORIES`, that means `misc` can safely be deleted and the port placed only in the other subdirectory.
 * If the port truly does not belong anywhere else, put it in [.filename]#misc#.
 
 If the category is not clearly defined, please put a comment to that effect in the https://bugs.freebsd.org/submit/[port submission] in the bug database so we can discuss it before we import it. As a committer, send a note to the {freebsd-ports} so we can discuss it first. Too often, new ports are imported to the wrong category only to be moved right away.
 
 [[proposing-categories]]
 === Proposing a New Category
 
 As the Ports Collection has grown over time, various new categories have been introduced. New categories can either be _virtual_ categories-those that do not have a corresponding subdirectory in the ports tree- or _physical_ categories-those that do. This section discusses the issues involved in creating a new physical category. Read it thouroughly before proposing a new one.
 
 Our existing practice has been to avoid creating a new physical category unless either a large number of ports would logically belong to it, or the ports that would belong to it are a logically distinct group that is of limited general interest (for instance, categories related to spoken human languages), or preferably both.
 
 The rationale for this is that such a change creates a link:{committers-guide}#ports[fair amount of work] for both the committers and also for all users who track changes to the Ports Collection. In addition, proposed category changes just naturally seem to attract controversy. (Perhaps this is because there is no clear consensus on when a category is "too big", nor whether categories should lend themselves to browsing (and thus what number of categories would be an ideal number), and so forth.)
 
 Here is the procedure:
 
 [.procedure]
 . Propose the new category on {freebsd-ports}. Include a detailed rationale for the new category, including why the existing categories are not sufficient, and the list of existing ports proposed to move. (If there are new ports pending in Bugzilla that would fit this category, list them too.) If you are the maintainer and/or submitter, respectively, mention that as it may help the case.
 . Participate in the discussion.
 . If it seems that there is support for the idea, file a PR which includes both the rationale and the list of existing ports that need to be moved. Ideally, this PR would also include these patches:
 
 ** [.filename]##Makefile##s for the new ports once they are repocopied
 ** [.filename]#Makefile# for the new category
 ** [.filename]#Makefile# for the old ports' categories
 ** [.filename]##Makefile##s for ports that depend on the old ports
 ** (for extra credit, include the other files that have to change, as per the procedure in the Committer's Guide.)
 
 . Since it affects the ports infrastructure and involves moving and patching many ports but also possibly running regression tests on the build cluster, assign the PR to the {portmgr}.
 . If that PR is approved, a committer will need to follow the rest of the procedure that is link:{committers-guide}#PORTS[outlined in the Committer's Guide].
 
 Proposing a new virtual category is similar to the above but much less involved, since no ports will actually have to move. In this case, the only patches to include in the PR would be those to add the new category to `CATEGORIES` of the affected ports.
 
 [[proposing-reorg]]
 === Proposing Reorganizing All the Categories
 
 Occasionally someone proposes reorganizing the categories with either a 2-level structure, or some other kind of keyword structure. To date, nothing has come of any of these proposals because, while they are very easy to make, the effort involved to retrofit the entire existing ports collection with any kind of reorganization is daunting to say the very least. Please read the history of these proposals in the mailing list archives before posting this idea. Furthermore, be prepared to be challenged to offer a working prototype.
 
 [[makefile-distfiles]]
 == The Distribution Files
 
 The second part of the [.filename]#Makefile# describes the files that must be downloaded to build the port, and where they can be downloaded.
 
 [[makefile-distname]]
 === `DISTNAME`
 
 `DISTNAME` is the name of the port as called by the authors of the software. `DISTNAME` defaults to `${PORTNAME}-${DISTVERSIONPREFIX}${DISTVERSION}${DISTVERSIONSUFFIX}`, and if not set, `DISTVERSION` defaults to `${PORTVERSION}` so override `DISTNAME` only if necessary. `DISTNAME` is only used in two places. First, the distribution file list (`DISTFILES`) defaults to `${DISTNAME}${EXTRACT_SUFX}`. Second, the distribution file is expected to extract into a subdirectory named `WRKSRC`, which defaults to [.filename]#work/${DISTNAME}#.
 
 Some vendor's distribution names which do not fit into the `${PORTNAME}-${PORTVERSION}`-scheme can be handled automatically by setting `DISTVERSIONPREFIX`, `DISTVERSION`, and `DISTVERSIONSUFFIX`. `PORTVERSION` will be derived from `DISTVERSION` automatically.
 
 [IMPORTANT]
 ====
 Only one of `PORTVERSION` and `DISTVERSION` can be set at a time. If `DISTVERSION` does not derive a correct `PORTVERSION`, do not use `DISTVERSION`.
 ====
 
 If the upstream version scheme can be derived into a ports-compatible version scheme, set some variable to the upstream version, _do not_ use `DISTVERSION` as the variable name. Set `PORTVERSION` to the computed version based on the variable you created, and set `DISTNAME` accordingly.
 
 If the upstream version scheme cannot easily be coerced into a ports-compatible value, set `PORTVERSION` to a sensible value, and set `DISTNAME` with `PORTNAME` with the verbatim upstream version.
 
 [[makefile-distname-ex1]]
 .Deriving `PORTVERSION` Manually
 [example]
 ====
 BIND9 uses a version scheme that is not compatible with the ports versions (it has `-` in its versions) and cannot be derived using `DISTVERSION` because after the 9.9.9 release, it will release a "patchlevels" in the form of `9.9.9-P1`. DISTVERSION would translate that into `9.9.9.p1`, which, in the ports versioning scheme means 9.9.9 pre-release 1, which is before 9.9.9 and not after. So `PORTVERSION` is manually derived from an `ISCVERSION` variable to output `9.9.9p1`.
 
 The order into which the ports framework, and pkg, will sort versions is checked using the `-t` argument of man:pkg-version[8]:
 
 [source,shell]
 ....
 % pkg version -t 9.9.9 9.9.9.p1
 > <.>
 % pkg version -t 9.9.9 9.9.9p1 
 < <.>
 ....
 
 <.> The `>` sign means that the first argument passed to `-t` is greater than the second argument. `9.9.9` is after `9.9.9.p1`.
 <.> The `<` sign means that the first argument passed to `-t` is less than the second argument. `9.9.9` is before `9.9.9p1`.
 
 In the port [.filename]#Makefile#, for example package:dns/bind99[], it is achieved by:
 
 [.programlisting]
 ....
 PORTNAME=	bind
 PORTVERSION=	${ISCVERSION:S/-P/P/:S/b/.b/:S/a/.a/:S/rc/.rc/} 
 CATEGORIES=	dns net
 MASTER_SITES=	ISC/bind9/${ISCVERSION} 
 PKGNAMESUFFIX=	99
 DISTNAME=	${PORTNAME}-${ISCVERSION} 
 
 MAINTAINER=	mat@FreeBSD.org
 COMMENT=	BIND DNS suite with updated DNSSEC and DNS64
 
 LICENSE=	ISCL
 
 # ISC releases things like 9.8.0-P1 or 9.8.1rc1, which our versioning does not like
 ISCVERSION=	9.9.9-P6
 ....
 
 Define upstream version in `ISCVERSION`, with a comment saying _why_ it is needed.
 Use `ISCVERSION` to get a ports-compatible `PORTVERSION`.
 Use `ISCVERSION` directly to get the correct URL for fetching the distribution file.
 Use `ISCVERSION` directly to name the distribution file.
 ====
 
 [[makefile-distname-ex2]]
 .Derive `DISTNAME` from `PORTVERSION`
 [example]
 ====
 From time to time, the distribution file name has little or no relation to the version of the software.
 
 In package:comms/kermit[], only the last element of the version is present in the distribution file:
 
 [.programlisting]
 ....
 PORTNAME=	kermit
 PORTVERSION=	9.0.304
 CATEGORIES=	comms ftp net
 MASTER_SITES=	ftp://ftp.kermitproject.org/kermit/test/tar/
 DISTNAME=	cku${PORTVERSION:E}-dev20
 ....
 
 The `:E` man:make[1] modifier returns the suffix of the variable, in this case, `304`. The distribution file is correctly generated as `cku304-dev20.tar.gz`.
 ====
 
 [[makefile-distname-ex3]]
 .Exotic Case 1
 [example]
 ====
 Sometimes, there is no relation between the software name, its version, and the distribution file it is distributed in.
 
 From package:audio/libworkman[]:
 
 [.programlisting]
 ....
 PORTNAME=       libworkman
 PORTVERSION=    1.4
 CATEGORIES=     audio
 MASTER_SITES=   LOCAL/jim
 DISTNAME=       ${PORTNAME}-1999-06-20
 ....
 
 ====
 
 [[makefile-distname-ex4]]
 .Exotic Case 2
 [example]
 ====
 In package:comms/librs232[], the distribution file is not versioned, so using <<makefile-dist_subdir,`DIST_SUBDIR`>> is needed:
 
 [.programlisting]
 ....
 PORTNAME=       librs232
 PORTVERSION=    20160710
 CATEGORIES=     comms
 MASTER_SITES=   http://www.teuniz.net/RS-232/
 DISTNAME=       RS-232
 DIST_SUBDIR=	${PORTNAME}-${PORTVERSION}
 ....
 
 ====
 
 [NOTE]
 ====
 `PKGNAMEPREFIX` and `PKGNAMESUFFIX` do not affect `DISTNAME`. Also note that if `WRKSRC` is equal to [.filename]#${WRKDIR}/${DISTNAME}# while the original source archive is named something other than `${PORTNAME}-${PORTVERSION}${EXTRACT_SUFX}`, leave `DISTNAME` alone- defining only `DISTFILES` is easier than both `DISTNAME` and `WRKSRC` (and possibly `EXTRACT_SUFX`).
 ====
 
 [[makefile-master_sites]]
 === `MASTER_SITES`
 
 Record the directory part of the FTP/HTTP-URL pointing at the original tarball in `MASTER_SITES`. Do not forget the trailing slash ([.filename]#/#)!
 
 The `make` macros will try to use this specification for grabbing the distribution file with `FETCH` if they cannot find it already on the system.
 
 It is recommended that multiple sites are included on this list, preferably from different continents. This will safeguard against wide-area network problems.
 
 [IMPORTANT]
 ====
 `MASTER_SITES` must not be blank. It must point to the actual site hosting the distribution files. It cannot point to web archives, or the FreeBSD distribution files cache sites. The only exception to this rule is ports that do not have any distribution files. For example, meta-ports do not have any distribution files, so `MASTER_SITES` does not need to be set.
 ====
 
 [[makefile-master_sites-shorthand]]
 ==== Using `MASTER_SITE_*` Variables
 
 Shortcut abbreviations are available for popular archives like SourceForge (`SOURCEFORGE`), GNU (`GNU`), or Perl CPAN (`PERL_CPAN`). `MASTER_SITES` can use them directly:
 
 [.programlisting]
 ....
 MASTER_SITES=	GNU/make
 ....
 
 The older expanded format still works, but all ports have been converted to the compact format. The expanded format looks like this:
 
 [.programlisting]
 ....
 MASTER_SITES=		${MASTER_SITE_GNU}
 MASTER_SITE_SUBDIR=	make
 ....
 
 These values and variables are defined in https://cgit.freebsd.org/ports/tree/Mk/bsd.sites.mk[Mk/bsd.sites.mk]. New entries are added often, so make sure to check the latest version of this file before submitting a port.
 
 [TIP]
 ====
 
 For any `MASTER_SITE_FOO` variable, the shorthand `_FOO_` can be used. For example, use:
 
 [.programlisting]
 ....
 MASTER_SITES=	FOO
 ....
 
 If `MASTER_SITE_SUBDIR` is needed, use this:
 
 [.programlisting]
 ....
 MASTER_SITES=	FOO/bar
 ....
 
 ====
 
 [NOTE]
 ====
 Some `MASTER_SITE_*` names are quite long, and for ease of use, shortcuts have been defined:
 
 [[makefile-master_sites-shortcut]]
 .Shortcuts for `MASTER_SITE_*` Macros
 [cols="1,1", frame="none", options="header"]
 |===
 | Macro
 | Shortcut
 
 |`PERL_CPAN`
 |`CPAN`
 
 |`GITHUB`
 |`GH`
 
 |`GITHUB_CLOUD`
 |`GHC`
 
 |`LIBREOFFICE_DEV`
 |`LODEV`
 
 |`NETLIB`
 |`NL`
 
 |`RUBYGEMS`
 |`RG`
 
 |`SOURCEFORGE`
 |`SF`
 |===
 ====
 
 [[makefile-master_sites-magic]]
 ==== Magic MASTER_SITES Macros
 
 Several "magic" macros exist for popular sites with a predictable directory structure. For these, just use the abbreviation and the system will choose a subdirectory automatically. For a port named `Stardict`, of version `1.2.3`, and hosted on SourceForge, adding this line:
 
 [.programlisting]
 ....
 MASTER_SITES=	SF
 ....
 
 infers a subdirectory named `/project/stardict/stardict/1.2.3`. If the inferred directory is incorrect, it can be overridden:
 
 [.programlisting]
 ....
 MASTER_SITES=	SF/stardict/WyabdcRealPeopleTTS/${PORTVERSION}
 ....
 
 This can also be written as
 
 [.programlisting]
 ....
 MASTER_SITES=	SF
 MASTER_SITE_SUBDIR=	stardict/WyabdcRealPeopleTTS/${PORTVERSION}
 ....
 
 [[makefile-master_sites-popular]]
 .Magic `MASTER_SITES` Macros
 [cols="1,1", frame="none", options="header"]
 |===
 | Macro
 | Assumed subdirectory
 
 |`APACHE_COMMONS_BINARIES`
 |`${PORTNAME:S,commons-,,}`
 
 |`APACHE_COMMONS_SOURCE`
 |`${PORTNAME:S,commons-,,}`
 
 |`APACHE_JAKARTA`
 |`${PORTNAME:S,-,/,}/source`
 
 |`BERLIOS`
 |`${PORTNAME:tl}.berlios`
 
 |`CHEESESHOP`
 |`source/${DISTNAME:C/(.).\*/\1/}/${DISTNAME:C/(.*)-[0-9].*/\1/}`
 
 |`CPAN`
 |`${PORTNAME:C/-.*//}`
 
 |`DEBIAN`
 |`pool/main/${PORTNAME:C/^((lib)?.).*$/\1/}/${PORTNAME}`
 
 |`FARSIGHT`
 |`${PORTNAME}`
 
 |`FESTIVAL`
 |`${PORTREVISION}`
 
 |`GCC`
 |`releases/${DISTNAME}`
 
 |`GENTOO`
 |`distfiles`
 
 |`GIMP`
 |`${PORTNAME}/${PORTVERSION:R}/`
 
 |`GH`
 |`${GH_ACCOUNT}/${GH_PROJECT}/tar.gz/${GH_TAGNAME}?dummy=/`
 
 |`GHC`
 |`${GH_ACCOUNT}/${GH_PROJECT}/`
 
 |`GNOME`
 |`sources/${PORTNAME}/${PORTVERSION:C/^([0-9]+\.[0-9]+).*/\1/}`
 
 |`GNU`
 |`${PORTNAME}`
 
 |`GNUPG`
 |`${PORTNAME}`
 
 |`GNU_ALPHA`
 |`${PORTNAME}`
 
 |`HORDE`
 |`${PORTNAME}`
 
 |`LODEV`
 |`${PORTNAME}`
 
 |`MATE`
 |`${PORTVERSION:C/^([0-9]+\.[0-9]+).*/\1/}`
 
 |`MOZDEV`
 |`${PORTNAME:tl}`
 
 |`NL`
 |`${PORTNAME}`
 
 |`QT`
 |`archive/qt/${PORTVERSION:R}`
 
 |`SAMBA`
 |`${PORTNAME}`
 
 |`SAVANNAH`
 |`${PORTNAME:tl}`
 
 |`SF`
 |`${PORTNAME:tl}/${PORTNAME:tl}/${PORTVERSION}`
 |===
 
 [[makefile-master_sites-github]]
 === `USE_GITHUB`
 
 If the distribution file comes from a specific commit or tag on https://github.com[GitHub] for which there is no officially released file, there is an easy way to set the right `DISTNAME` and `MASTER_SITES` automatically. These variables are available:
 
 [[makefile-master_sites-github-description]]
 .`USE_GITHUB` Description
 [cols="1,1,1", options="header"]
 |===
 | Variable
 | Description
 | Default
 
 |`GH_ACCOUNT`
 |Account name of the GitHub user hosting the project
 |`${PORTNAME}`
 
 |`GH_PROJECT`
 |Name of the project on GitHub
 |`${PORTNAME}`
 
 |`GH_TAGNAME`
 |Name of the tag to download (2.0.1, hash, ...) Using the name of a branch here is incorrect. It is also possible to use the hash of a commit id to do a snapshot.
 |`${DISTVERSIONPREFIX}${DISTVERSION}${DISTVERSIONSUFFIX}`
 
 |`GH_SUBDIR`
 |When the software needs an additional distribution file to be extracted within `${WRKSRC}`, this variable can be used. See the examples in <<makefile-master_sites-github-multiple>> for more information.
 |(none)
 
 |`GH_TUPLE`
 |`GH_TUPLE` allows putting `GH_ACCOUNT`, `GH_PROJECT`, `GH_TAGNAME`, and `GH_SUBDIR` into a single variable. The format is _account_`:`_project_`:`_tagname_`:`_group_`/`_subdir_. The `/`_subdir_ part is optional. It is helpful when there is more than one GitHub project from which to fetch.
 |===
 
 [IMPORTANT]
 ====
 Do not use `GH_TUPLE` for the default distribution file, as it has no default.
 ====
 
 [[makefile-master_sites-github-ex1]]
 .Simple Use of `USE_GITHUB`
 [example]
 ====
 
 While trying to make a port for version `1.2.7` of pkg from the FreeBSD user on github, at https://github.com/freebsd/pkg[], The [.filename]#Makefile# would end up looking like this (slightly stripped for the example):
 
 [.programlisting]
 ....
 PORTNAME=	pkg
 DISTVERSION=	1.2.7
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	freebsd
 ....
 
 It will automatically have `MASTER_SITES` set to `GH` and `WRKSRC` to `${WRKDIR}/pkg-1.2.7`.
 ====
 
 [[makefile-master_sites-github-ex2]]
 .More Complete Use of `USE_GITHUB`
 [example]
 ====
 While trying to make a port for the bleeding edge version of pkg from the FreeBSD user on github, at https://github.com/freebsd/pkg[], the [.filename]#Makefile# ends up looking like this (slightly stripped for the example):
 
 [.programlisting]
 ....
 PORTNAME=	pkg-devel
 DISTVERSION=	1.3.0.a.20140411
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	freebsd
 GH_PROJECT=	pkg
 GH_TAGNAME=	6dbb17b
 ....
 
 It will automatically have `MASTER_SITES` set to `GH` and `WRKSRC` to `${WRKDIR}/pkg-6dbb17b`.
 
 [TIP]
 ****
 
 `20140411` is the date of the commit referenced in `GH_TAGNAME`, not the date the [.filename]#Makefile# is edited, or the date the commit is made.
 ****
 
 ====
 
 [[makefile-master_sites-github-ex3]]
 .Use of `USE_GITHUB` with `DISTVERSIONPREFIX`
 [example]
 ====
 From time to time, `GH_TAGNAME` is a slight variation from `DISTVERSION`. For example, if the version is `1.0.2`, the tag is `v1.0.2`. In those cases, it is possible to use `DISTVERSIONPREFIX` or `DISTVERSIONSUFFIX`:
 
 [.programlisting]
 ....
 PORTNAME=	foo
 DISTVERSIONPREFIX=	v
 DISTVERSION=	1.0.2
 
 USE_GITHUB=	yes
 ....
 
 It will automatically set `GH_TAGNAME` to `v1.0.2`, while `WRKSRC` will be kept to `${WRKDIR}/foo-1.0.2`.
 ====
 
 [[makefile-master_sites-github-ex4]]
 .Using `USE_GITHUB` When Upstream Does Not Use Versions
 [example]
 ====
 If there never was a version upstream, do not invent one like `0.1` or `1.0`. Create the port with a `DISTVERSION` of `g__YYYYMMDD__`, where `g` is for Git, and `_YYYYMMDD_` represents the date the commit referenced in `GH_TAGNAME`.
 
 [.programlisting]
 ....
 PORTNAME=	bar
 DISTVERSION=	g20140411
 
 USE_GITHUB=	yes
 GH_TAGNAME=	c472d66b
 ....
 
 This creates a versioning scheme that increases over time, and that is still before version `0` (see <<makefile-versions-ex-pkg-version>> for details on man:pkg-version[8]):
 
 [source,shell]
 ....
 % pkg version -t g20140411 0
 <
 ....
 
 Which means using `PORTEPOCH` will not be needed in case upstream decides to cut versions in the future.
 ====
 
 [[makefile-master_sites-github-ex5]]
 .Using `USE_GITHUB` to Access a Commit Between Two Versions
 [example]
 ====
 
 If the current version of the software uses a Git tag, and the port needs to be updated to a newer, intermediate version, without a tag, use man:git-describe[1] to find out the version to use:
 
 [source,shell]
 ....
 % git describe --tags f0038b1
 v0.7.3-14-gf0038b1
 ....
 
 `v0.7.3-14-gf0038b1` can be split into three parts:
 
 `v0.7.3`::
 This is the last Git tag that appears in the commit history before the requested commit.
 
 `-14`::
 This means that the requested commit, `f0038b1`, is the 14th commit after the `v0.7.3` tag.
 
 `-gf0038b1`::
 The `-g` means "Git", and the `f0038b1` is the commit hash that this reference points to.
 
 [.programlisting]
 ....
 PORTNAME=	bar
 DISTVERSIONPREFIX=  v
 DISTVERSION=	0.7.3-14
 DISTVERSIONSUFFIX=  -gf0038b1
 
 USE_GITHUB=	yes
 ....
 
 This creates a versioning scheme that increases over time (well, over commits), and does not conflict with the creation of a `0.7.4` version. (See <<makefile-versions-ex-pkg-version>> for details on man:pkg-version[8]):
 
 [source,shell]
 ....
 % pkg version -t 0.7.3 0.7.3.14
 <
 % pkg version -t 0.7.3.14 0.7.4
 <
 ....
 
 [NOTE]
 ****
 If the requested commit is the same as a tag, a shorter description is shown by default. The longer version is equivalent:
 
 [source,shell]
 ....
 % git describe --tags c66c71d
 v0.7.3
 
 % git describe --tags --long c66c71d
 v0.7.3-0-gc66c71d
 ....
 
 ****
 
 ====
 
 [[makefile-master_sites-github-multiple]]
 ==== Fetching Multiple Files from GitHub
 
 The `USE_GITHUB` framework also supports fetching multiple distribution files from different places in GitHub. It works in a way very similar to <<porting-master-sites-n>>.
 
 Multiple values are added to `GH_ACCOUNT`, `GH_PROJECT`, and `GH_TAGNAME`. Each different value is assigned a group. The main value can either have no group, or the `:DEFAULT` group. A value can be omitted if it is the same as the default as listed in <<makefile-master_sites-github-description>>.
 
 `GH_TUPLE` can also be used when there are a lot of distribution files. It helps keep the account, project, tagname, and group information at the same place.
 
 For each group, a `${WRKSRC_group}` helper variable is created, containing the directory into which the file has been extracted. The `${WRKSRC_group}` variables can be used to move directories around during `post-extract`, or add to `CONFIGURE_ARGS`, or whatever is needed so that the software builds correctly.
 
 [CAUTION]
 ====
 
 The `:__group__` part _must_ be used for _only one_ distribution file. It is used as a unique key and using it more than once will overwrite the previous values.
 ====
 
 [NOTE]
 ====
 As this is only syntactic sugar above `DISTFILES` and `MASTER_SITES`, the group names must adhere to the restrictions on group names outlined in <<porting-master-sites-n>>
 ====
 
 When fetching multiple files from GitHub, sometimes the default distribution file is not fetched from GitHub. To disable fetching the default distribution, set:
 
 [.programlisting]
 ....
 USE_GITHUB=	nodefault
 ....
 
 [IMPORTANT]
 ====
 When using `USE_GITHUB=nodefault`, the [.filename]#Makefile# must set `DISTFILES` in its crossref:porting-order[porting-order-portname,top block]. The definition should be:
 
 [.programlisting]
 ....
 DISTFILES=    ${DISTNAME}${EXTRACT_SUFX}
 ....
 
 ====
 
 [[makefile-master_sites-github-multi]]
 .Use of `USE_GITHUB` with Multiple Distribution Files
 [example]
 ====
 From time to time, there is a need to fetch more than one distribution file. For example, when the upstream git repository uses submodules. This can be done easily using groups in the `GH_*` variables:
 
 [.programlisting]
 ....
 PORTNAME=	foo
 DISTVERSION=	1.0.2
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	bar:icons,contrib
 GH_PROJECT=	foo-icons:icons foo-contrib:contrib
 GH_TAGNAME=	1.0:icons fa579bc:contrib
 GH_SUBDIR=	ext/icons:icons
 
 CONFIGURE_ARGS=	--with-contrib=${WRKSRC_contrib}
 ....
 
 This will fetch three distribution files from github. The default one comes from [.filename]#foo/foo# and is version `1.0.2`. The second one, with the `icons` group, comes from [.filename]#bar/foo-icons# and is in version `1.0`. The third one comes from [.filename]#bar/foo-contrib# and uses the Git commit `fa579bc`. The distribution files are named [.filename]#foo-foo-1.0.2_GH0.tar.gz#, [.filename]#bar-foo-icons-1.0_GH0.tar.gz#, and [.filename]#bar-foo-contrib-fa579bc_GH0.tar.gz#.
 
 All the distribution files are extracted in `${WRKDIR}` in their respective subdirectories. The default file is still extracted in `${WRKSRC}`, in this case, [.filename]#${WRKDIR}/foo-1.0.2#. Each additional distribution file is extracted in `${WRKSRC_group}`. Here, for the `icons` group, it is called `${WRKSRC_icons}` and it contains [.filename]#${WRKDIR}/foo-icons-1.0#. The file with the `contrib` group is called `${WRKSRC_contrib}` and contains `${WRKDIR}/foo-contrib-fa579bc`.
 
 The software's build system expects to find the icons in a [.filename]#ext/icons# subdirectory in its sources, so `GH_SUBDIR` is used. `GH_SUBDIR` makes sure that [.filename]#ext# exists, but that [.filename]#ext/icons# does not already exist. Then it does this:
 
 [.programlisting]
 ....
 post-extract:
       @${MV} ${WRKSRC_icons} ${WRKSRC}/ext/icons
 ....
 
 ====
 
 [[makefile-master_sites-github-multi2]]
 .Use of `USE_GITHUB` with Multiple Distribution Files Using `GH_TUPLE`
 [example]
 ====
 
 This is functionally equivalent to <<makefile-master_sites-github-multi>>, but using `GH_TUPLE`:
 
 [.programlisting]
 ....
 PORTNAME=	foo
 DISTVERSION=	1.0.2
 
 USE_GITHUB=	yes
 GH_TUPLE=	bar:foo-icons:1.0:icons/ext/icons \
 		bar:foo-contrib:fa579bc:contrib
 
 CONFIGURE_ARGS=	--with-contrib=${WRKSRC_contrib}
 ....
 
 Grouping was used in the previous example with `bar:icons,contrib`. Some redundant information is present with `GH_TUPLE` because grouping is not possible.
 ====
 
 [[makefile-master_sites-github-submodules]]
 .How to Use `USE_GITHUB` with Git Submodules?
 [example]
 ====
 Ports with GitHub as an upstream repository sometimes use submodules. See man:git-submodule[1] for more information.
 
 The problem with submodules is that each is a separate repository. As such, they each must be fetched separately.
 
 Using package:finance/moneymanagerex[] as an example, its GitHub repository is https://github.com/moneymanagerex/moneymanagerex[]. It has a https://github.com/moneymanagerex/moneymanagerex/blob/master/.gitmodules[.gitmodules] file at the root. This file describes all the submodules used in this repository, and lists additional repositories needed. This file will tell what additional repositories are needed:
 
 [.programlisting]
 ....
 [submodule "lib/wxsqlite3"]
 	path = lib/wxsqlite3
 	url = https://github.com/utelle/wxsqlite3.git
 [submodule "3rd/mongoose"]
 	path = 3rd/mongoose
 	url = https://github.com/cesanta/mongoose.git
 [submodule "3rd/LuaGlue"]
 	path = 3rd/LuaGlue
 	url = https://github.com/moneymanagerex/LuaGlue.git
 [submodule "3rd/cgitemplate"]
 	path = 3rd/cgitemplate
 	url = https://github.com/moneymanagerex/html-template.git
 [...]
 ....
 
 The only information missing from that file is the commit hash or tag to use as a version. This information is found after cloning the repository:
 
 [source,shell]
 ....
 % git clone --recurse-submodules https://github.com/moneymanagerex/moneymanagerex.git
 Cloning into 'moneymanagerex'...
 remote: Counting objects: 32387, done.
 [...]
 Submodule '3rd/LuaGlue' (https://github.com/moneymanagerex/LuaGlue.git) registered for path '3rd/LuaGlue'
 Submodule '3rd/cgitemplate' (https://github.com/moneymanagerex/html-template.git) registered for path '3rd/cgitemplate'
 Submodule '3rd/mongoose' (https://github.com/cesanta/mongoose.git) registered for path '3rd/mongoose'
 Submodule 'lib/wxsqlite3' (https://github.com/utelle/wxsqlite3.git) registered for path 'lib/wxsqlite3'
 [...]
 Cloning into '/home/mat/work/freebsd/ports/finance/moneymanagerex/moneymanagerex/3rd/LuaGlue'...
 Cloning into '/home/mat/work/freebsd/ports/finance/moneymanagerex/moneymanagerex/3rd/cgitemplate'...
 Cloning into '/home/mat/work/freebsd/ports/finance/moneymanagerex/moneymanagerex/3rd/mongoose'...
 Cloning into '/home/mat/work/freebsd/ports/finance/moneymanagerex/moneymanagerex/lib/wxsqlite3'...
 [...]
 Submodule path '3rd/LuaGlue': checked out 'c51d11a247ee4d1e9817dfa2a8da8d9e2f97ae3b'
 Submodule path '3rd/cgitemplate': checked out 'cd434eeeb35904ebcd3d718ba29c281a649b192c'
 Submodule path '3rd/mongoose': checked out '2140e5992ab9a3a9a34ce9a281abf57f00f95cda'
 Submodule path 'lib/wxsqlite3': checked out 'fb66eb230d8aed21dec273b38c7c054dcb7d6b51'
 [...]
 % cd moneymanagerex
 % git submodule status
  c51d11a247ee4d1e9817dfa2a8da8d9e2f97ae3b 3rd/LuaGlue (heads/master)
  cd434eeeb35904ebcd3d718ba29c281a649b192c 3rd/cgitemplate (cd434ee)
  2140e5992ab9a3a9a34ce9a281abf57f00f95cda 3rd/mongoose (6.2-138-g2140e59)
  fb66eb230d8aed21dec273b38c7c054dcb7d6b51 lib/wxsqlite3 (v3.4.0)
 [...]
 ....
 
 It can also be found on GitHub. Each subdirectory that is a submodule is shown as `_directory @ hash_`, for example, `mongoose @ 2140e59`.
 
 [NOTE]
 ****
 While getting the information from GitHub seems more straightforward, the information found using `git submodule status` will provide more meaningful information. For example, here, ``lib/wxsqlite3``'s commit hash `fb66eb2` correspond to `v3.4.0`. Both can be used interchangeably, but when a tag is available, use it.
 ****
 
 Now that all the required information has been gathered, the [.filename]#Makefile# can be written (only GitHub-related lines are shown):
 
 [.programlisting]
 ....
 PORTNAME=	moneymanagerex
 DISTVERSIONPREFIX=	v
 DISTVERSION=	1.3.0
 
 USE_GITHUB=	yes
 GH_TUPLE=	utelle:wxsqlite3:v3.4.0:wxsqlite3/lib/wxsqlite3 \
 		moneymanagerex:LuaGlue:c51d11a:lua_glue/3rd/LuaGlue \
 		moneymanagerex:html-template:cd434ee:html_template/3rd/cgitemplate \
 		cesanta:mongoose:2140e59:mongoose/3rd/mongoose \
 		[...]
 ....
 
 ====
 
 [[makefile-master_sites-gitlab]]
 === `USE_GITLAB`
 
 Similar to GitHub, if the distribution file comes from https://gitlab.com[gitlab.com] or is hosting the GitLab software, these variables are available for use and might need to be set.
 
 [[makefile-master_sites-gitlab-description]]
 .`USE_GITLAB` Description
 [cols="1,1,1", options="header"]
 |===
 | Variable
 | Description
 | Default
 
 |`GL_SITE`
 |Site name hosting the GitLab project
 |https://gitlab.com
 
 |`GL_ACCOUNT`
 |Account name of the GitLab user hosting the project
 |`${PORTNAME}`
 
 |`GL_PROJECT`
 |Name of the project on GitLab
 |`${PORTNAME}`
 
 |`GL_COMMIT`
 |The commit hash to download. Must be the full 160 bit, 40 character hex sha1 hash. This is a required variable for GitLab.
 |`(none)`
 
 |`GL_SUBDIR`
 |When the software needs an additional distribution file to be extracted within `${WRKSRC}`, this variable can be used. See the examples in <<makefile-master_sites-gitlab-multiple>> for more information.
 |(none)
 
 |`GL_TUPLE`
 |`GL_TUPLE` allows putting `GL_SITE`, `GL_ACCOUNT`, `GL_PROJECT`, `GL_COMMIT`, and `GL_SUBDIR` into a single variable. The format is _site_`:`_account_`:`_project_`:`_commit_`:`_group_`/`_subdir_. The _site_`:` and `/`_subdir_ part is optional. It is helpful when there are more than one GitLab project from which to fetch.
 |===
 
 [[makefile-master_sites-gitlab-ex1]]
 .Simple Use of `USE_GITLAB`
 [example]
 ====
 While trying to make a port for version `1.14` of libsignon-glib from the accounts-sso user on gitlab.com, at https://gitlab.com/accounts-sso/libsignon-glib[], The [.filename]#Makefile# would end up looking like this for fetching the distribution files:
 
 [.programlisting]
 ....
 PORTNAME=	libsignon-glib
 DISTVERSION=	1.14
 
 USE_GITLAB=	yes
 GL_ACCOUNT=	accounts-sso
 GL_COMMIT=	e90302e342bfd27bc8c9132ab9d0ea3d8723fd03
 ....
 
 It will automatically have `MASTER_SITES` set to https://gitlab.com[gitlab.com] and `WRKSRC` to `${WRKDIR}/libsignon-glib-e90302e342bfd27bc8c9132ab9d0ea3d8723fd03-e90302e342bfd27bc8c9132ab9d0ea3d8723fd03`.
 ====
 
 [[makefile-master_sites-gitlab-ex2]]
 .More Complete Use of `USE_GITLAB`
 [example]
 ====
 
 A more complete use of the above if port had no versioning and foobar from the foo user on project bar on a self hosted GitLab site `https://gitlab.example.com`, the [.filename]#Makefile# ends up looking like this for fetching distribution files:
 
 [.programlisting]
 ....
 PORTNAME=	foobar
 DISTVERSION=	g20170906
 
 USE_GITLAB=	yes
 GL_SITE=	https://gitlab.example.com
 GL_ACCOUNT=	foo
 GL_PROJECT=	bar
 GL_COMMIT=	9c1669ce60c3f4f5eb43df874d7314483fb3f8a6
 ....
 
 It will have `MASTER_SITES` set to `"https://gitlab.example.com"` and `WRKSRC` to `${WRKDIR}/bar-9c1669ce60c3f4f5eb43df874d7314483fb3f8a6-9c1669ce60c3f4f5eb43df874d7314483fb3f8a6`.
 
 [TIP]
 `20170906` is the date of the commit referenced in `GL_COMMIT`, not the date the [.filename]#Makefile# is edited, or the date the commit to the FreeBSD ports tree is made.
 
 [NOTE]
 ``GL_SITE``'s protocol, port and webroot can all be modified in the same variable.
 
 ====
 
 [[makefile-master_sites-gitlab-multiple]]
 ==== Fetching Multiple Files from GitLab
 
 The `USE_GITLAB` framework also supports fetching multiple distribution files from different places from GitLab and GitLab hosted sites. It works in a way very similar to <<porting-master-sites-n>> and <<makefile-master_sites-gitlab-multiple>>.
 
 Multiple values are added to `GL_SITE`, `GL_ACCOUNT`, `GL_PROJECT` and `GL_COMMIT`. Each different value is assigned a group. <<makefile-master_sites-gitlab-description>>.
 
 `GL_TUPLE` can also be used when there are a lot of distribution files. It helps keep the site, account, project, commit, and group information at the same place.
 
 For each group, a `${WRKSRC_group}` helper variable is created, containing the directory into which the file has been extracted. The `${WRKSRC_group}` variables can be used to move directories around during `post-extract`, or add to `CONFIGURE_ARGS`, or whatever is needed so that the software builds correctly.
 
 [CAUTION]
 ====
 
 The `:__group__` part _must_ be used for _only one_ distribution file. It is used as a unique key and using it more than once will overwrite the previous values.
 ====
 
 [NOTE]
 ====
 As this is only syntactic sugar above `DISTFILES` and `MASTER_SITES`, the group names must adhere to the restrictions on group names outlined in <<porting-master-sites-n>>
 ====
 
 When fetching multiple files using GitLab, sometimes the default distribution file is not fetched from a GitLab site. To disable fetching the default distribution, set:
 
 [.programlisting]
 ....
 USE_GITLAB=	nodefault
 ....
 
 [IMPORTANT]
 ====
 When using `USE_GITLAB=nodefault`, the [.filename]#Makefile# must set `DISTFILES` in its <<porting-order-portname,top block>>. The definition should be:
 
 [.programlisting]
 ....
 DISTFILES=    ${DISTNAME}${EXTRACT_SUFX}
 ....
 
 ====
 
 [[makefile-master_sites-gitlab-multi]]
 .Use of `USE_GITLAB` with Multiple Distribution Files
 [example]
 ====
 
 From time to time, there is a need to fetch more than one distribution file. For example, when the upstream git repository uses submodules. This can be done easily using groups in the `GL_*` variables:
 
 [.programlisting]
 ....
 PORTNAME=	foo
 DISTVERSION=	1.0.2
 
 USE_GITLAB=	yes
 GL_SITE=	https://gitlab.example.com:9434/gitlab:icons
 GL_ACCOUNT=	bar:icons,contrib
 GL_PROJECT=	foo-icons:icons foo-contrib:contrib
 GL_COMMIT=	c189207a55da45305c884fe2b50e086fcad4724b ae7368cab1ca7ca754b38d49da064df87968ffe4:icons 9e4dd76ad9b38f33fdb417a4c01935958d5acd2a:contrib
 GL_SUBDIR=	ext/icons:icons
 
 CONFIGURE_ARGS= --with-contrib=${WRKSRC_contrib}
 ....
 
 This will fetch two distribution files from gitlab.com and one from `gitlab.example.com` hosting GitLab. The default one comes from [.filename]#https://gitlab.com/foo/foo# and commit is `c189207a55da45305c884fe2b50e086fcad4724b`. The second one, with the `icons` group, comes from [.filename]#https://gitlab.example.com:9434/gitlab/bar/foo-icons# and commit is `ae7368cab1ca7ca754b38d49da064df87968ffe4`. The third one comes from [.filename]#https://gitlab.com/bar/foo-contrib# and is commit `9e4dd76ad9b38f33fdb417a4c01935958d5acd2a`. The distribution files are named [.filename]#foo-foo-c189207a55da45305c884fe2b50e086fcad4724b_GL0.tar.gz#, [.filename]#bar-foo-icons-ae7368cab1ca7ca754b38d49da064df87968ffe4_GL0.tar.gz#, and [.filename]#bar-foo-contrib-9e4dd76ad9b38f33fdb417a4c01935958d5acd2a_GL0.tar.gz#.
 
 All the distribution files are extracted in `${WRKDIR}` in their respective subdirectories. The default file is still extracted in `${WRKSRC}`, in this case, [.filename]#${WRKDIR}/foo-c189207a55da45305c884fe2b50e086fcad4724b-c189207a55da45305c884fe2b50e086fcad4724b#. Each additional distribution file is extracted in `${WRKSRC_group}`. Here, for the `icons` group, it is called `${WRKSRC_icons}` and it contains [.filename]#${WRKDIR}/foo-icons-ae7368cab1ca7ca754b38d49da064df87968ffe4-ae7368cab1ca7ca754b38d49da064df87968ffe4#. The file with the `contrib` group is called `${WRKSRC_contrib}` and contains `${WRKDIR}/foo-contrib-9e4dd76ad9b38f33fdb417a4c01935958d5acd2a-9e4dd76ad9b38f33fdb417a4c01935958d5acd2a`.
 
 The software's build system expects to find the icons in a [.filename]#ext/icons# subdirectory in its sources, so `GL_SUBDIR` is used. `GL_SUBDIR` makes sure that [.filename]#ext# exists, but that [.filename]#ext/icons# does not already exist. Then it does this:
 
 [.programlisting]
 ....
 post-extract:
         @${MV} ${WRKSRC_icons} ${WRKSRC}/ext/icons
 ....
 
 ====
 
 [[makefile-master_sites-gitlab-multi2]]
 .Use of `USE_GITLAB` with Multiple Distribution Files Using `GL_TUPLE`
 [example]
 ====
 This is functionally equivalent to <<makefile-master_sites-gitlab-multi>>, but using `GL_TUPLE`:
 
 [.programlisting]
 ....
 PORTNAME=	foo
 DISTVERSION=	1.0.2
 
 USE_GITLAB=	yes
 GL_COMMIT=	c189207a55da45305c884fe2b50e086fcad4724b
 GL_TUPLE=	https://gitlab.example.com:9434/gitlab:bar:foo-icons:ae7368cab1ca7ca754b38d49da064df87968ffe4:icons/ext/icons \
 		bar:foo-contrib:9e4dd76ad9b38f33fdb417a4c01935958d5acd2a:contrib
 
 CONFIGURE_ARGS= --with-contrib=${WRKSRC_contrib}
 ....
 
 Grouping was used in the previous example with `bar:icons,contrib`. Some redundant information is present with `GL_TUPLE` because grouping is not possible.
 ====
 
 [[makefile-extract_sufx]]
 === `EXTRACT_SUFX`
 
 If there is one distribution file, and it uses an odd suffix to indicate the compression mechanism, set `EXTRACT_SUFX`.
 
 For example, if the distribution file was named [.filename]#foo.tar.gzip# instead of the more normal [.filename]#foo.tar.gz#, write:
 
 [.programlisting]
 ....
 DISTNAME=	foo
 EXTRACT_SUFX=	.tar.gzip
 ....
 
 The `USES=tar[:__xxx__]`, `USES=lha` or `USES=zip` automatically set `EXTRACT_SUFX` to the most common archives extensions as necessary, see crossref:uses[uses,Using `USES` Macros] for more details. If neither of these are set then `EXTRACT_SUFX` defaults to `.tar.gz`.
 
 [NOTE]
 ====
 As `EXTRACT_SUFX` is only used in `DISTFILES`, only set one of them..
 ====
 
 [[makefile-distfiles-definition]]
 === `DISTFILES`
 
 Sometimes the names of the files to be downloaded have no resemblance to the name of the port. For example, it might be called [.filename]#source.tar.gz# or similar. In other cases the application's source code might be in several different archives, all of which must be downloaded.
 
 If this is the case, set `DISTFILES` to be a space separated list of all the files that must be downloaded.
 
 [.programlisting]
 ....
 DISTFILES=	source1.tar.gz source2.tar.gz
 ....
 
 If not explicitly set, `DISTFILES` defaults to `${DISTNAME}${EXTRACT_SUFX}`.
 
 [[makefile-extract_only]]
 === `EXTRACT_ONLY`
 
 If only some of the `DISTFILES` must be extracted-for example, one of them is the source code, while another is an uncompressed document-list the filenames that must be extracted in `EXTRACT_ONLY`.
 
 [.programlisting]
 ....
 DISTFILES=	source.tar.gz manual.html
 EXTRACT_ONLY=	source.tar.gz
 ....
 
 When none of the `DISTFILES` need to be uncompressed, set `EXTRACT_ONLY` to the empty string.
 
 [.programlisting]
 ....
 EXTRACT_ONLY=
 ....
 
 [[porting-patchfiles]]
 === `PATCHFILES`
 
 If the port requires some additional patches that are available by FTP or HTTP, set `PATCHFILES` to the names of the files and `PATCH_SITES` to the URL of the directory that contains them (the format is the same as `MASTER_SITES`).
 
 If the patch is not relative to the top of the source tree (that is, `WRKSRC`) because it contains some extra pathnames, set `PATCH_DIST_STRIP` accordingly. For instance, if all the pathnames in the patch have an extra `foozolix-1.0/` in front of the filenames, then set `PATCH_DIST_STRIP=-p1`.
 
 Do not worry if the patches are compressed; they will be decompressed automatically if the filenames end with [.filename]#.Z#, [.filename]#.gz#, [.filename]#.bz2# or [.filename]#.xz#.
 
 If the patch is distributed with some other files, such as documentation, in a compressed tarball, using `PATCHFILES` is not possible. If that is the case, add the name and the location of the patch tarball to `DISTFILES` and `MASTER_SITES`. Then, use `EXTRA_PATCHES` to point to those files and [.filename]#bsd.port.mk# will automatically apply them. In particular, do _not_ copy patch files into [.filename]#${PATCHDIR}#. That directory may not be writable.
 
 [TIP]
 ====
 
 If there are multiple patches and they need mixed values for the strip parameter, it can be added alongside the patch name in `PATCHFILES`, e.g:
 
 [.programlisting]
 ....
 PATCHFILES=	patch1 patch2:-p1
 ....
 
 This does not conflict with <<porting-master-sites-n,the master site grouping feature>>, adding a group also works:
 
 [.programlisting]
 ....
 PATCHFILES=	patch2:-p1:source2
 ....
 
 ====
 
 [NOTE]
 ====
 The tarball will have been extracted alongside the regular source by then, so there is no need to explicitly extract it if it is a regular compressed tarball. Take extra care not to overwrite something that already exists in that directory if extracting it manually. Also, do not forget to add a command to remove the copied patch in the `pre-clean` target.
 ====
 
 [[porting-master-sites-n]]
 === Multiple Distribution or Patches Files from Multiple Locations
 
 (Consider this to be a somewhat "advanced topic"; those new to this document may wish to skip this section at first).
 
 This section has information on the fetching mechanism known as both `MASTER_SITES:n` and `MASTER_SITES_NN`. We will refer to this mechanism as `MASTER_SITES:n`.
 
 A little background first. OpenBSD has a neat feature inside `DISTFILES` and `PATCHFILES` which allows files and patches to be postfixed with `:n` identifiers. Here, `n` can be any word containing `[0-9a-zA-Z_]` and denote a group designation. For example:
 
 [.programlisting]
 ....
 DISTFILES=	alpha:0 beta:1
 ....
 
 In OpenBSD, distribution file [.filename]#alpha# will be associated with variable `MASTER_SITES0` instead of our common `MASTER_SITES` and [.filename]#beta# with `MASTER_SITES1`.
 
 This is a very interesting feature which can decrease that endless search for the correct download site.
 
 Just picture 2 files in `DISTFILES` and 20 sites in `MASTER_SITES`, the sites slow as hell where [.filename]#beta# is carried by all sites in `MASTER_SITES`, and [.filename]#alpha# can only be found in the 20th site. It would be such a waste to check all of them if the maintainer knew this beforehand, would it not? Not a good start for that lovely weekend!
 
 Now that you have the idea, just imagine more `DISTFILES` and more `MASTER_SITES`. Surely our "distfiles survey meister" would appreciate the relief to network strain that this would bring.
 
 In the next sections, information will follow on the FreeBSD implementation of this idea. We improved a bit on OpenBSD's concept.
 
 [IMPORTANT]
 ====
 The group names cannot have dashes in them (`-`), in fact, they cannot have any characters out of the `[a-zA-Z0-9_]` range. This is because, while man:make[1] is ok with variable names containing dashes, man:sh[1] is not.
 ====
 
 [[porting-master-sites-n-simplified]]
 ==== Simplified Information
 
 This section explains how to quickly prepare fine grained fetching of multiple distribution files and patches from different sites and subdirectories. We describe here a case of simplified `MASTER_SITES:n` usage. This will be sufficient for most scenarios. More detailed information are available in <<ports-master-sites-n-detailed>>.
 
 Some applications consist of multiple distribution files that must be downloaded from a number of different sites. For example, Ghostscript consists of the core of the program, and then a large number of driver files that are used depending on the user's printer. Some of these driver files are supplied with the core, but many others must be downloaded from a variety of different sites.
 
 To support this, each entry in `DISTFILES` may be followed by a colon and a "group name". Each site listed in `MASTER_SITES` is then followed by a colon, and the group that indicates which distribution files are downloaded from this site.
 
 For example, consider an application with the source split in two parts, [.filename]#source1.tar.gz# and [.filename]#source2.tar.gz#, which must be downloaded from two different sites. The port's [.filename]#Makefile# would include lines like <<ports-master-sites-n-example-simple-use-one-file-per-site>>.
 
 [[ports-master-sites-n-example-simple-use-one-file-per-site]]
 .Simplified Use of `MASTER_SITES:n` with One File Per Site
 [example]
 ====
 
 [.programlisting]
 ....
 MASTER_SITES=	ftp://ftp1.example.com/:source1 \
 		http://www.example.com/:source2
 DISTFILES=	source1.tar.gz:source1 \
 		source2.tar.gz:source2
 ....
 
 ====
 
 Multiple distribution files can have the same group. Continuing the previous example, suppose that there was a third distfile, [.filename]#source3.tar.gz#, that is downloaded from `ftp.example2.com`. The [.filename]#Makefile# would then be written like <<ports-master-sites-n-example-simple-use-more-than-one-file-per-site>>.
 
 [[ports-master-sites-n-example-simple-use-more-than-one-file-per-site]]
 .Simplified Use of `MASTER_SITES:n` with More Than One File Per Site
 [example]
 ====
 
 [.programlisting]
 ....
 MASTER_SITES=	ftp://ftp.example.com/:source1 \
 		http://www.example.com/:source2
 DISTFILES=	source1.tar.gz:source1 \
 		source2.tar.gz:source2 \
 		source3.tar.gz:source2
 ....
 
 ====
 
 [[ports-master-sites-n-detailed]]
 ==== Detailed Information
 
 Okay, so the previous example did not reflect the new port's needs? In this section we will explain in detail how the fine grained fetching mechanism `MASTER_SITES:n` works and how it can be used.
 
 . Elements can be postfixed with `:__n__` where _n_ is `[^:,]+`, that is, _n_ could conceptually be any alphanumeric string but we will limit it to `[a-zA-Z_][0-9a-zA-Z_]+` for now.
-+ 
++
 Moreover, string matching is case sensitive; that is, `n` is different from `N`.
-+ 
++
 However, these words cannot be used for postfixing purposes since they yield special meaning: `default`, `all` and `ALL` (they are used internally in item <<porting-master-sites-n-what-changes-in-port-targets, ii>>). Furthermore, `DEFAULT` is a special purpose word (check item <<porting-master-sites-n-DEFAULT-group,3>>).
 . Elements postfixed with `:n` belong to the group `n`, `:m` belong to group `m` and so forth.
 +
 [[porting-master-sites-n-DEFAULT-group]]
 . Elements without a postfix are groupless, they all belong to the special group `DEFAULT`. Any elements postfixed with `DEFAULT`, is just being redundant unless an element belongs to both `DEFAULT` and other groups at the same time (check item <<porting-master-sites-n-comma-operator,5>>).
-+ 
++
 These examples are equivalent but the first one is preferred:
 +
 [.programlisting]
 ....
 MASTER_SITES=	alpha
 ....
 +
 [.programlisting]
 ....
 MASTER_SITES=	alpha:DEFAULT
 ....
 
 . Groups are not exclusive, an element may belong to several different groups at the same time and a group can either have either several different elements or none at all.
 +
 [[porting-master-sites-n-comma-operator]]
 . When an element belongs to several groups at the same time, use the comma operator (`,`).
-+ 
++
 Instead of repeating it several times, each time with a different postfix, we can list several groups at once in a single postfix. For instance, `:m,n,o` marks an element that belongs to group `m`, `n` and `o`.
-+ 
++
 All these examples are equivalent but the last one is preferred:
 +
 [.programlisting]
 ....
 MASTER_SITES=	alpha alpha:SOME_SITE
 ....
 +
 [.programlisting]
 ....
 MASTER_SITES=	alpha:DEFAULT alpha:SOME_SITE
 ....
 +
 [.programlisting]
 ....
 MASTER_SITES=	alpha:SOME_SITE,DEFAULT
 ....
 +
 [.programlisting]
 ....
 MASTER_SITES=	alpha:DEFAULT,SOME_SITE
 ....
 
 . All sites within a given group are sorted according to `MASTER_SORT_AWK`. All groups within `MASTER_SITES` and `PATCH_SITES` are sorted as well.
 +
 [[porting-master-sites-n-group-semantics]]
 . Group semantics can be used in any of the variables `MASTER_SITES`, `PATCH_SITES`, `MASTER_SITE_SUBDIR`, `PATCH_SITE_SUBDIR`, `DISTFILES`, and `PATCHFILES` according to this syntax:
 .. All `MASTER_SITES`, `PATCH_SITES`, `MASTER_SITE_SUBDIR` and `PATCH_SITE_SUBDIR` elements must be terminated with the forward slash `/` character. If any elements belong to any groups, the group postfix `:__n__` must come right after the terminator `/`. The `MASTER_SITES:n` mechanism relies on the existence of the terminator `/` to avoid confusing elements where a `:n` is a valid part of the element with occurrences where `:n` denotes group `n`. For compatibility purposes, since the `/` terminator was not required before in both `MASTER_SITE_SUBDIR` and `PATCH_SITE_SUBDIR` elements, if the postfix immediate preceding character is not a `/` then `:n` will be considered a valid part of the element instead of a group postfix even if an element is postfixed with `:n`. See both <<ports-master-sites-n-example-detailed-use-master-site-subdir>> and <<ports-master-sites-n-example-detailed-use-complete-example-master-sites>>.
 +
 [[ports-master-sites-n-example-detailed-use-master-site-subdir]]
 .Detailed Use of `MASTER_SITES:n` in `MASTER_SITE_SUBDIR`
 [example]
 ====
 
 [.programlisting]
 ....
 MASTER_SITE_SUBDIR=	old:n new/:NEW
 ....
 
 *** Directories within group `DEFAULT` -> old:n
 *** Directories within group `NEW` -> new
 
 ====
 +
 [[ports-master-sites-n-example-detailed-use-complete-example-master-sites]]
 .Detailed Use of `MASTER_SITES:n` with Comma Operator, Multiple Files, Multiple Sites and Multiple Subdirectories
 [example]
 ====
 
 [.programlisting]
 ....
 MASTER_SITES=	http://site1/%SUBDIR%/ http://site2/:DEFAULT \
 		http://site3/:group3 http://site4/:group4 \
 		http://site5/:group5 http://site6/:group6 \
 		http://site7/:DEFAULT,group6 \
 		http://site8/%SUBDIR%/:group6,group7 \
 		http://site9/:group8
 DISTFILES=	file1 file2:DEFAULT file3:group3 \
 		file4:group4,group5,group6 file5:grouping \
 		file6:group7
 MASTER_SITE_SUBDIR=	directory-trial:1 directory-n/:groupn \
 		directory-one/:group6,DEFAULT \
 		directory
 ....
 
 The previous example results in this fine grained fetching. Sites are listed in the exact order they will be used.
 
 *** [.filename]#file1# will be fetched from
 
 **** `MASTER_SITE_OVERRIDE`
 **** http://site1/directory-trial:1/
 **** http://site1/directory-one/
 **** http://site1/directory/
 **** http://site2/
 **** http://site7/
 **** `MASTER_SITE_BACKUP`
 
 *** [.filename]#file2# will be fetched exactly as [.filename]#file1# since they both belong to the same group
 
 **** `MASTER_SITE_OVERRIDE`
 **** http://site1/directory-trial:1/
 **** http://site1/directory-one/
 **** http://site1/directory/
 **** http://site2/
 **** http://site7/
 **** `MASTER_SITE_BACKUP`
 
 *** [.filename]#file3# will be fetched from
 
 **** `MASTER_SITE_OVERRIDE`
 **** http://site3/
 **** `MASTER_SITE_BACKUP`
 
 *** [.filename]#file4# will be fetched from
 
 **** `MASTER_SITE_OVERRIDE`
 **** http://site4/
 **** http://site5/
 **** http://site6/
 **** http://site7/
 **** http://site8/directory-one/
 **** `MASTER_SITE_BACKUP`
 
 *** [.filename]#file5# will be fetched from
 
 **** `MASTER_SITE_OVERRIDE`
 **** `MASTER_SITE_BACKUP`
 
 *** [.filename]#file6# will be fetched from
 
 **** `MASTER_SITE_OVERRIDE`
 **** http://site8/
 **** `MASTER_SITE_BACKUP`
 
 ====
 
 . How do I group one of the special macros from [.filename]#bsd.sites.mk#, for example, SourceForge (`SF`)?
-+ 
++
 This has been simplified as much as possible. See <<ports-master-sites-n-example-detailed-use-master-site-sourceforge>>.
 +
 [[ports-master-sites-n-example-detailed-use-master-site-sourceforge]]
 .Detailed Use of `MASTER_SITES:n` with SourceForge (`SF`)
 [example]
 ====
 
 [.programlisting]
 ....
 MASTER_SITES=	http://site1/ SF/something/1.0:sourceforge,TEST
 DISTFILES=	something.tar.gz:sourceforge
 ....
 
 [.filename]#something.tar.gz# will be fetched from all sites within SourceForge.
 ====
 . How do I use this with `PATCH*`?
-+ 
++
 All examples were done with `MASTER*` but they work exactly the same for `PATCH*` ones as can be seen in <<ports-master-sites-n-example-detailed-use-patch-sites>>.
 +
 [[ports-master-sites-n-example-detailed-use-patch-sites]]
 .Simplified Use of `MASTER_SITES:n` with `PATCH_SITES`
 [example]
 ====
 
 [.programlisting]
 ....
 PATCH_SITES=	http://site1/ http://site2/:test
 PATCHFILES=	patch1:test
 ....
 
 ====
 
 [[port-master-sites-n-what-changed]]
 ==== What Does Change for Ports? What Does Not?
 
 [lowerroman]
 . All current ports remain the same. The `MASTER_SITES:n` feature code is only activated if there are elements postfixed with `:__n__` like elements according to the aforementioned syntax rules, especially as shown in item <<porting-master-sites-n-group-semantics, 7>>.
 +
 [[porting-master-sites-n-what-changes-in-port-targets]]
 . The port targets remain the same: `checksum`, `makesum`, `patch`, `configure`, `build`, etc. With the obvious exceptions of `do-fetch`, `fetch-list`, `master-sites` and `patch-sites`.
 
 ** `do-fetch`: deploys the new grouping postfixed `DISTFILES` and `PATCHFILES` with their matching group elements within both `MASTER_SITES` and `PATCH_SITES` which use matching group elements within both `MASTER_SITE_SUBDIR` and `PATCH_SITE_SUBDIR`. Check <<ports-master-sites-n-example-detailed-use-complete-example-master-sites>>.
 ** `fetch-list`: works like old `fetch-list` with the exception that it groups just like `do-fetch`.
 ** `master-sites` and `patch-sites`: (incompatible with older versions) only return the elements of group `DEFAULT`; in fact, they execute targets `master-sites-default` and `patch-sites-default` respectively.
-+ 
++
 Furthermore, using target either `master-sites-all` or `patch-sites-all` is preferred to directly checking either `MASTER_SITES` or `PATCH_SITES`. Also, directly checking is not guaranteed to work in any future versions. Check item <<porting-master-sites-n-new-port-targets-master-sites-all, B>> for more information on these new port targets.
 
 . New port targets
 .. There are `master-sites-_n_` and `patch-sites-_n_` targets which will list the elements of the respective group _n_ within `MASTER_SITES` and `PATCH_SITES` respectively. For instance, both `master-sites-DEFAULT` and `patch-sites-DEFAULT` will return the elements of group `DEFAULT`, `master-sites-test` and `patch-sites-test` of group `test`, and thereon.
 +
 [[porting-master-sites-n-new-port-targets-master-sites-all]]
 .. There are new targets `master-sites-all` and `patch-sites-all` which do the work of the old `master-sites` and `patch-sites` ones. They return the elements of all groups as if they all belonged to the same group with the caveat that it lists as many `MASTER_SITE_BACKUP` and `MASTER_SITE_OVERRIDE` as there are groups defined within either `DISTFILES` or `PATCHFILES`; respectively for `master-sites-all` and `patch-sites-all`.
 
 [[makefile-dist_subdir]]
 === `DIST_SUBDIR`
 
 Do not let the port clutter [.filename]#/usr/ports/distfiles#. If the port requires a lot of files to be fetched, or contains a file that has a name that might conflict with other ports (for example, [.filename]#Makefile#), set `DIST_SUBDIR` to the name of the port (`${PORTNAME}` or `${PKGNAMEPREFIX}${PORTNAME}` are fine). This will change `DISTDIR` from the default [.filename]#/usr/ports/distfiles# to [.filename]#/usr/ports/distfiles/${DIST_SUBDIR}#, and in effect puts everything that is required for the port into that subdirectory.
 
 It will also look at the subdirectory with the same name on the backup master site at http://distcache.FreeBSD.org[http://distcache.FreeBSD.org] (Setting `DISTDIR` explicitly in [.filename]#Makefile# will not accomplish this, so please use `DIST_SUBDIR`.)
 
 [NOTE]
 ====
 This does not affect `MASTER_SITES` defined in the [.filename]#Makefile#.
 ====
 
 [[makefile-maintainer]]
 == `MAINTAINER`
 
 Set your mail-address here. Please. _:-)_
 
 Only a single address without the comment part is allowed as a `MAINTAINER` value. The format used is `user@hostname.domain`. Please do not include any descriptive text such as a real name in this entry. That merely confuses the Ports infrastructure and most tools using it.
 
 The maintainer is responsible for keeping the port up to date and making sure that it works correctly. For a detailed description of the responsibilities of a port maintainer, refer to link:{contributing}#maintain-port[The challenge for port maintainers].
 
 [NOTE]
 ====
 A maintainer volunteers to keep a port in good working order. Maintainers have the primary responsibility for their ports, but not exclusive ownership. Ports exist for the benefit of the community and, in reality, belong to the community. What this means is that people other than the maintainer can make changes to a port. Large changes to the Ports Collection might require changes to many ports. The FreeBSD Ports Management Team or members of other teams might modify ports to fix dependency issues or other problems, like a version bump for a shared library update.
 
 Some types of fixes have "blanket approval" from the {portmgr}, allowing any committer to fix those categories of problems on any port. These fixes do not need approval from the maintainer.
 
 Blanket approval for most ports applies to fixes like infrastructure changes, or trivial and _tested_ build and runtime fixes. The current list is available in link:{committers-guide}#ports-qa-misc-blanket-approval[Ports section of the Committer's Guide].
 ====
 
 Other changes to the port will be sent to the maintainer for review and approval before being committed. If the maintainer does not respond to an update request after two weeks (excluding major public holidays), then that is considered a maintainer timeout, and the update can be made without explicit maintainer approval. If the maintainer does not respond within three months, or if there have been three consecutive timeouts, then that maintainer is considered absent without leave, and all of their ports can be assigned back to the pool. Exceptions to this are anything maintained by the {portmgr}, or the {security-officer}. No unauthorized commits may ever be made to ports maintained by those groups.
 
 We reserve the right to modify the maintainer's submission to better match existing policies and style of the Ports Collection without explicit blessing from the submitter or the maintainer. Also, large infrastructural changes can result in a port being modified without the maintainer's consent. These kinds of changes will never affect the port's functionality.
 
 The {portmgr} reserves the right to revoke or override anyone's maintainership for any reason, and the {security-officer} reserves the right to revoke or override maintainership for security reasons.
 
 [[makefile-comment]]
 == `COMMENT`
 
 The comment is a one-line description of a port shown by `pkg info`. Please follow these rules when composing it:
 
 . The COMMENT string should be 70 characters or less.
 . Do _not_ include the package name or version number of software.
 . The comment must begin with a capital and end without a period.
 . Do not start with an indefinite article (that is, A or An).
 . Capitalize names such as Apache, JavaScript, or Perl.
 . Use a serial comma for lists of words: "green, red, and blue."
 . Check for spelling errors.
 
 Here is an example:
 
 [.programlisting]
 ....
 COMMENT=	Cat chasing a mouse all over the screen
 ....
 
 The COMMENT variable immediately follows the MAINTAINER variable in the [.filename]#Makefile#.
 
 [[licenses]]
 == Licenses
 
 Each port must document the license under which it is available. If it is not an OSI approved license it must also document any restrictions on redistribution.
 
 [[licenses-license]]
 === `LICENSE`
 
 A short name for the license or licenses if more than one license apply.
 
 If it is one of the licenses listed in <<licenses-license-list>>, only `LICENSE_FILE` and `LICENSE_DISTFILES` variables can be set.
 
 If this is a license that has not been defined in the ports framework (see <<licenses-license-list>>), the `LICENSE_PERMS` and `LICENSE_NAME` must be set, along with either `LICENSE_FILE` or `LICENSE_TEXT`. `LICENSE_DISTFILES` and `LICENSE_GROUPS` can also be set, but are not required.
 
 The predefined licenses are shown in <<licenses-license-list>>. The current list is always available in [.filename]#Mk/bsd.licenses.db.mk#.
 
 [[licenses-license-ex1]]
 .Simplest Usage, Predefined Licenses
 [example]
 ====
 
 When the [.filename]#README# of some software says "This software is under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version." but does not provide the license file, use this:
 
 [.programlisting]
 ....
 LICENSE=	LGPL21+
 ....
 
 When the software provides the license file, use this:
 
 [.programlisting]
 ....
 LICENSE=	LGPL21+
 LICENSE_FILE=	${WRKSRC}/COPYING
 ....
 
 ====
 
 For the predefined licenses, the default permissions are `dist-mirror dist-sell pkg-mirror pkg-sell auto-accept`.
 
 [[licenses-license-list]]
 .Predefined License List
 [cols="1,1,1,1", frame="none", options="header"]
 |===
 | Short Name
 | Name
 | Group
 | Permissions
 
 |`AGPLv3`
 |GNU Affero General Public License version 3
 |`FSF GPL OSI`
 |(default)
 
 |`AGPLv3+`
 |GNU Affero General Public License version 3 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`APACHE10`
 |Apache License 1.0
 |`FSF`
 |(default)
 
 |`APACHE11`
 |Apache License 1.1
 |`FSF OSI`
 |(default)
 
 |`APACHE20`
 |Apache License 2.0
 |`FSF OSI`
 |(default)
 
 |`ART10`
 |Artistic License version 1.0
 |`OSI`
 |(default)
 
 |`ART20`
 |Artistic License version 2.0
 |`FSF GPL OSI`
 |(default)
 
 |`ARTPERL10`
 |Artistic License (perl) version 1.0
 |`OSI`
 |(default)
 
 |`BSD`
 |BSD license Generic Version (deprecated)
 |`FSF OSI COPYFREE`
 |(default)
 
 |`BSD2CLAUSE`
 |BSD 2-clause "Simplified" License
 |`FSF OSI COPYFREE`
 |(default)
 
 |`BSD3CLAUSE`
 |BSD 3-clause "New" or "Revised" License
 |`FSF OSI COPYFREE`
 |(default)
 
 |`BSD4CLAUSE`
 |BSD 4-clause "Original" or "Old" License
 |`FSF`
 |(default)
 
 |`BSL`
 |Boost Software License
 |`FSF OSI COPYFREE`
 |(default)
 
 |`CC-BY-1.0`
 |Creative Commons Attribution 1.0
 |
 |(default)
 
 |`CC-BY-2.0`
 |Creative Commons Attribution 2.0
 |
 |(default)
 
 |`CC-BY-2.5`
 |Creative Commons Attribution 2.5
 |
 |(default)
 
 |`CC-BY-3.0`
 |Creative Commons Attribution 3.0
 |
 |(default)
 
 |`CC-BY-4.0`
 |Creative Commons Attribution 4.0
 |
 |(default)
 
 |`CC-BY-NC-1.0`
 |Creative Commons Attribution Non Commercial 1.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-2.0`
 |Creative Commons Attribution Non Commercial 2.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-2.5`
 |Creative Commons Attribution Non Commercial 2.5
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-3.0`
 |Creative Commons Attribution Non Commercial 3.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-4.0`
 |Creative Commons Attribution Non Commercial 4.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-ND-1.0`
 |Creative Commons Attribution Non Commercial No Derivatives 1.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-ND-2.0`
 |Creative Commons Attribution Non Commercial No Derivatives 2.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-ND-2.5`
 |Creative Commons Attribution Non Commercial No Derivatives 2.5
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-ND-3.0`
 |Creative Commons Attribution Non Commercial No Derivatives 3.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-ND-4.0`
 |Creative Commons Attribution Non Commercial No Derivatives 4.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-SA-1.0`
 |Creative Commons Attribution Non Commercial Share Alike 1.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-SA-2.0`
 |Creative Commons Attribution Non Commercial Share Alike 2.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-SA-2.5`
 |Creative Commons Attribution Non Commercial Share Alike 2.5
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-SA-3.0`
 |Creative Commons Attribution Non Commercial Share Alike 3.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-NC-SA-4.0`
 |Creative Commons Attribution Non Commercial Share Alike 4.0
 |
 |`dist-mirror``pkg-mirror``auto-accept`
 
 |`CC-BY-ND-1.0`
 |Creative Commons Attribution No Derivatives 1.0
 |
 |(default)
 
 |`CC-BY-ND-2.0`
 |Creative Commons Attribution No Derivatives 2.0
 |
 |(default)
 
 |`CC-BY-ND-2.5`
 |Creative Commons Attribution No Derivatives 2.5
 |
 |(default)
 
 |`CC-BY-ND-3.0`
 |Creative Commons Attribution No Derivatives 3.0
 |
 |(default)
 
 |`CC-BY-ND-4.0`
 |Creative Commons Attribution No Derivatives 4.0
 |
 |(default)
 
 |`CC-BY-SA-1.0`
 |Creative Commons Attribution Share Alike 1.0
 |
 |(default)
 
 |`CC-BY-SA-2.0`
 |Creative Commons Attribution Share Alike 2.0
 |
 |(default)
 
 |`CC-BY-SA-2.5`
 |Creative Commons Attribution Share Alike 2.5
 |
 |(default)
 
 |`CC-BY-SA-3.0`
 |Creative Commons Attribution Share Alike 3.0
 |
 |(default)
 
 |`CC-BY-SA-4.0`
 |Creative Commons Attribution Share Alike 4.0
 |
 |(default)
 
 |`CC0-1.0`
 |Creative Commons Zero v1.0 Universal
 |`FSF GPL COPYFREE`
 |(default)
 
 |`CDDL`
 |Common Development and Distribution License
 |`FSF OSI`
 |(default)
 
 |`CPAL-1.0`
 |Common Public Attribution License
 |`FSF OSI`
 |(default)
 
 |`ClArtistic`
 |Clarified Artistic License
 |`FSF GPL OSI`
 |(default)
 
 |`EPL`
 |Eclipse Public License
 |`FSF OSI`
 |(default)
 
 |`GFDL`
 |GNU Free Documentation License
 |`FSF`
 |(default)
 
 |`GMGPL`
 |GNAT Modified General Public License
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv1`
 |GNU General Public License version 1
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv1+`
 |GNU General Public License version 1 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv2`
 |GNU General Public License version 2
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv2+`
 |GNU General Public License version 2 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv3`
 |GNU General Public License version 3
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv3+`
 |GNU General Public License version 3 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv3RLE`
 |GNU GPL version 3 Runtime Library Exception
 |`FSF GPL OSI`
 |(default)
 
 |`GPLv3RLE+`
 |GNU GPL version 3 Runtime Library Exception (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`ISCL`
 |Internet Systems Consortium License
 |`FSF GPL OSI COPYFREE`
 |(default)
 
 |`LGPL20`
 |GNU Library General Public License version 2.0
 |`FSF GPL OSI`
 |(default)
 
 |`LGPL20+`
 |GNU Library General Public License version 2.0 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`LGPL21`
 |GNU Lesser General Public License version 2.1
 |`FSF GPL OSI`
 |(default)
 
 |`LGPL21+`
 |GNU Lesser General Public License version 2.1 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`LGPL3`
 |GNU Lesser General Public License version 3
 |`FSF GPL OSI`
 |(default)
 
 |`LGPL3+`
 |GNU Lesser General Public License version 3 (or later)
 |`FSF GPL OSI`
 |(default)
 
 |`LPPL10`
 |LaTeX Project Public License version 1.0
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`LPPL11`
 |LaTeX Project Public License version 1.1
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`LPPL12`
 |LaTeX Project Public License version 1.2
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`LPPL13`
 |LaTeX Project Public License version 1.3
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`LPPL13a`
 |LaTeX Project Public License version 1.3a
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`LPPL13b`
 |LaTeX Project Public License version 1.3b
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`LPPL13c`
 |LaTeX Project Public License version 1.3c
 |`FSF OSI`
 |`dist-mirror dist-sell`
 
 |`MIT`
 |MIT license / X11 license
 |`COPYFREE FSF GPL OSI`
 |(default)
 
 |`MPL10`
 |Mozilla Public License version 1.0
 |`FSF OSI`
 |(default)
 
 |`MPL11`
 |Mozilla Public License version 1.1
 |`FSF OSI`
 |(default)
 
 |`MPL20`
 |Mozilla Public License version 2.0
 |`FSF OSI`
 |(default)
 
 |`NCSA`
 |University of Illinois/NCSA Open Source License
 |`COPYFREE FSF GPL OSI`
 |(default)
 
 |`NONE`
 |No license specified
 |
 |`none`
 
 |`OFL10`
 |SIL Open Font License version 1.0 (http://scripts.sil.org/OFL)
 |`FONTS`
 |(default)
 
 |`OFL11`
 |SIL Open Font License version 1.1 (http://scripts.sil.org/OFL)
 |`FONTS`
 |(default)
 
 |`OWL`
 |Open Works License (owl.apotheon.org)
 |`COPYFREE`
 |(default)
 
 |`OpenSSL`
 |OpenSSL License
 |`FSF`
 |(default)
 
 |`PD`
 |Public Domain
 |`GPL COPYFREE`
 |(default)
 
 |`PHP202`
 |PHP License version 2.02
 |`FSF OSI`
 |(default)
 
 |`PHP30`
 |PHP License version 3.0
 |`FSF OSI`
 |(default)
 
 |`PHP301`
 |PHP License version 3.01
 |`FSF OSI`
 |(default)
 
 |`PSFL`
 |Python Software Foundation License
 |`FSF GPL OSI`
 |(default)
 
 |`PostgreSQL`
 |PostgreSQL License
 |`FSF GPL OSI COPYFREE`
 |(default)
 
 |`RUBY`
 |Ruby License
 |`FSF`
 |(default)
 
 |`UNLICENSE`
 |The Unlicense
 |`COPYFREE FSF GPL`
 |(default)
 
 |`WTFPL`
 |Do What the Fuck You Want To Public License version 2
 |`GPL FSF COPYFREE`
 |(default)
 
 |`WTFPL1`
 |Do What the Fuck You Want To Public License version 1
 |`GPL FSF COPYFREE`
 |(default)
 
 |`ZLIB`
 |zlib License
 |`GPL FSF OSI`
 |(default)
 
 |`ZPL21`
 |Zope Public License version 2.1
 |`GPL OSI`
 |(default)
 |===
 
 [[licenses-license_perms]]
 === `LICENSE_PERMS` and `LICENSE_PERMS_NAME_`
 
 Permissions. use `none` if empty.
 
 .License Permissions List
 [[licenses-license_perms-dist-mirror]]
 `dist-mirror`::
 Redistribution of the distribution files is permitted. The distribution files will be added to the FreeBSD `MASTER_SITE_BACKUP` CDN.
 
 [[licenses-license_perms-no-dist-mirror]]
 `no-dist-mirror`::
 Redistribution of the distribution files is prohibited. This is equivalent to setting crossref:special[porting-restrictions-restricted,`RESTRICTED`]. The distribution files will _not_ be added to the FreeBSD `MASTER_SITE_BACKUP` CDN.
 
 [[licenses-license_perms-dist-sell]]
 `dist-sell`::
 Selling of distribution files is permitted. The distribution files will be present on the installer images.
 
 [[licenses-license_perms-no-dist-sell]]
 `no-dist-sell`::
 Selling of distribution files is prohibited. This is equivalent to setting crossref:special[porting-restrictions-no_cdrom,`NO_CDROM`].
 
 [[licenses-license_perms-pkg-mirror]]
 `pkg-mirror`::
 Free redistribution of package is permitted. The package will be distributed on the FreeBSD package CDN https://pkg.freebsd.org/[https://pkg.freebsd.org/].
 
 [[licenses-license_perms-no-pkg-mirror]]
 `no-pkg-mirror`::
 Free redistribution of package is prohibited. Equivalent to setting crossref:special[porting-restrictions-no_package,`NO_PACKAGE`]. The package will _not_ be distributed from the FreeBSD package CDN https://pkg.freebsd.org/[https://pkg.freebsd.org/].
 
 [[licenses-license_perms-pkg-sell]]
 `pkg-sell`::
 Selling of package is permitted. The package will be present on the installer images.
 
 [[licenses-license_perms-no-pkg-sell]]
 `no-pkg-sell`::
 Selling of package is prohibited. This is equivalent to setting crossref:special[porting-restrictions-no_cdrom,`NO_CDROM`]. The package will _not_ be present on the installer images.
 
 [[licenses-license_perms-auto-accept]]
 `auto-accept`::
 License is accepted by default. Prompts to accept a license are not displayed unless the user has defined `LICENSES_ASK`. Use this unless the license states the user must accept the terms of the license.
 
 [[licenses-license_perms-no-auto-accept]]
 `no-auto-accept`::
 License is not accepted by default. The user will always be asked to confirm the acceptance of this license. This must be used if the license states that the user must accept its terms.
 
 When both `_permission_` and `no-_permission_` is present the `no-_permission_` will cancel `_permission_`.
 
 When `_permission_` is not present, it is considered to be a `no-_permission_`.
 
 [WARNING]
 ====
 Some missing permissions will prevent a port (and all ports depending on it) from being usable by package users:
 
 A port without the `auto-accept` permission will never be be built and all the ports depending on it will be ignored.
 
 A port without the `pkg-mirror` permission will be removed, as well as all the ports depending on it, after the build and they will ever end up being distributed.
 ====
 
 [[licenses-license_perms-ex1]]
 .Nonstandard License
 [example]
 ====
 Read the terms of the license and translate those using the available permissions.
 
 [.programlisting]
 ....
 LICENSE=        UNKNOWN
 LICENSE_NAME=   unknown
 LICENSE_TEXT=   This program is NOT in public domain.\
                 It can be freely distributed for non-commercial purposes only.
 LICENSE_PERMS=  dist-mirror no-dist-sell pkg-mirror no-pkg-sell auto-accept
 ....
 
 ====
 
 [[licenses-license_perms-ex2]]
 .Standard and Nonstandard Licenses
 [example]
 ====
 
 Read the terms of the license and express those using the available permissions. In case of doubt, please ask for guidance on the {freebsd-ports}.
 
 [.programlisting]
 ....
 LICENSE=        WARSOW GPLv2
 LICENSE_COMB=   multi
 LICENSE_NAME_WARSOW=    Warsow Content License
 LICENSE_FILE_WARSOW=    ${WRKSRC}/docs/license.txt
 LICENSE_PERMS_WARSOW=   dist-mirror pkg-mirror auto-accept
 ....
 
 When the permissions of the GPLv2 and the UNKNOWN licenses are mixed, the port ends up with `dist-mirror dist-sell pkg-mirror pkg-sell auto-accept dist-mirror no-dist-sell pkg-mirror no-pkg-sell auto-accept`. The `no-_permissions_` cancel the _permissions_. The resulting list of permissions are _dist-mirror pkg-mirror auto-accept_. The distribution files and the packages will not be available on the installer images.
 ====
 
 [[licenses-license_groups]]
 === `LICENSE_GROUPS` and `LICENSE_GROUPS_NAME`
 
 Groups the license belongs.
 
 .Predefined License Groups List
 [[licenses-license_groups-FSF]]
 `FSF`::
 Free Software Foundation Approved, see the http://www.fsf.org/licensing[FSF Licensing & Compliance Team].
 
 [[licenses-license_groups-GPL]]
 `GPL`::
 GPL Compatible
 
 [[licenses-license_groups-OSI]]
 `OSI`::
 OSI Approved, see the Open Source Initiative http://opensource.org/licenses[Open Source Licenses] page.
 
 [[licenses-license_groups-COPYFREE]]
 `COPYFREE`::
 Comply with Copyfree Standard Definition, see the http://copyfree.org/standard/licenses[Copyfree Licenses] page.
 
 [[licenses-license_groups-FONTS]]
 `FONTS`::
 Font licenses
 
 [[licenses-license_name]]
 === `LICENSE_NAME` and `LICENSE_NAME_NAME`
 
 Full name of the license.
 
 [[licenses-license_name-ex1]]
 .`LICENSE_NAME`
 [example]
 ====
 
 [.programlisting]
 ....
 LICENSE=        UNRAR
 LICENSE_NAME=   UnRAR License
 LICENSE_FILE=   ${WRKSRC}/license.txt
 LICENSE_PERMS=  dist-mirror dist-sell pkg-mirror pkg-sell auto-accept
 ....
 
 ====
 
 [[licenses-license_file]]
 === `LICENSE_FILE` and `LICENSE_FILE_NAME`
 
 Full path to the file containing the license text, usually [.filename]#${WRKSRC}/some/file#. If the file is not in the distfile, and its content is too long to be put in <<licenses-license_text,`LICENSE_TEXT`>>, put it in a new file in [.filename]#${FILESDIR}#.
 
 [[licenses-license_file-ex1]]
 .`LICENSE_FILE`
 [example]
 ====
 
 [.programlisting]
 ....
 LICENSE=	GPLv3+
 LICENSE_FILE=	${WRKSRC}/COPYING
 ....
 
 ====
 
 [[licenses-license_text]]
 === `LICENSE_TEXT` and `LICENSE_TEXT_NAME`
 
 Text to use as a license. Useful when the license is not in the distribution files and its text is short.
 
 [[licenses-license_text-ex1]]
 .`LICENSE_TEXT`
 [example]
 ====
 [.programlisting]
 ....
 LICENSE=        UNKNOWN
 LICENSE_NAME=   unknown
 LICENSE_TEXT=   This program is NOT in public domain.\
                 It can be freely distributed for non-commercial purposes only,\
                 and THERE IS NO WARRANTY FOR THIS PROGRAM.
 LICENSE_PERMS=  dist-mirror no-dist-sell pkg-mirror no-pkg-sell auto-accept
 ....
 
 ====
 
 [[licenses-license_distfiles]]
 === `LICENSE_DISTFILES` and `LICENSE_DISTFILES_NAME`
 
 The distribution files to which the licenses apply. Defaults to all the distribution files.
 
 [[licenses-license_distfiles-ex1]]
 .`LICENSE_DISTFILES`
 [example]
 ====
 Used when the distribution files do not all have the same license. For example, one has a code license, and another has some artwork that cannot be redistributed:
 
 [.programlisting]
 ....
 MASTER_SITES=   SF/some-game
 DISTFILES=      ${DISTNAME}${EXTRACT_SUFX} artwork.zip
 
 LICENSE=        BSD3CLAUSE ARTWORK
 LICENSE_COMB=   dual
 LICENSE_NAME_ARTWORK=      The game artwork license
 LICENSE_TEXT_ARTWORK=      The README says that the files cannot be redistributed
 LICENSE_PERMS_ARTWORK=     pkg-mirror pkg-sell auto-accept
 LICENSE_DISTFILES_BSD3CLAUSE=   ${DISTNAME}${EXTRACT_SUFX}
 LICENSE_DISTFILES_ARTWORK= artwork.zip
 ....
 
 ====
 
 [[licenses-license_comb]]
 === `LICENSE_COMB`
 
 Set to `multi` if all licenses apply. Set to `dual` if any license applies. Defaults to `single`.
 
 [[licenses-license_comb-ex1]]
 .Dual Licenses
 [example]
 ====
 
 When a port says "This software may be distributed under the GNU General Public License or the Artistic License", it means that either license can be used. Use this:
 
 [.programlisting]
 ....
 LICENSE=	ART10 GPLv1
 LICENSE_COMB=   dual
 ....
 
 If license files are provided, use this:
 
 [.programlisting]
 ....
 LICENSE=	ART10 GPLv1
 LICENSE_COMB=   dual
 LICENSE_FILE_ART10=     ${WRKSRC}/Artistic
 LICENSE_FILE_GPLv1=     ${WRKSRC}/Copying
 ....
 
 ====
 
 [[licenses-license_comb-ex2]]
 .Multiple Licenses
 [example]
 ====
 
 When part of a port has one license, and another part has a different license, use `multi`:
 
 [.programlisting]
 ....
 LICENSE=	GPLv2 LGPL21+
 LICENSE_COMB=	multi
 ....
 
 ====
 
 [[makefile-portscout]]
 == `PORTSCOUT`
 
 Portscout is an automated distfile check utility for the FreeBSD Ports Collection, described in detail in crossref:keeping-up[distfile-survey,Portscout: the FreeBSD Ports Distfile Scanner].
 
 `PORTSCOUT` defines special conditions within which the Portscout distfile scanner is restricted.
 
 Situations where `PORTSCOUT` is set include:
 
 * When distfiles have to be ignored for specific versions. For example, to exclude version _8.2_ and version _8.3_ from distfile version checks because they are known to be broken, add:
 +
 [.programlisting]
 ....
 PORTSCOUT=	skipv:8.2,8.3
 ....
 
 * When distfile version checks have to be disabled completely. For example, if a port is not going to be updated ever again, add:
 +
 [.programlisting]
 ....
 PORTSCOUT=	ignore:1
 ....
 
 * When specific versions or specific major and minor revisions of a distfile must be checked. For example, if only version _0.6.4_ must be monitored because newer versions have compatibility issues with FreeBSD, add:
 +
 [.programlisting]
 ....
 PORTSCOUT=	limit:^0\.6\.4
 ....
 
 * When URLs listing the available versions differ from the download URLs. For example, to limit distfile version checks to the download page for the package:databases/pgtune[] port, add:
 +
 [.programlisting]
 ....
 PORTSCOUT=	site:http://pgfoundry.org/frs/?group_id=1000416
 ....
 
 [[makefile-depend]]
 == Dependencies
 
 Many ports depend on other ports. This is a very convenient feature of most Unix-like operating systems, including FreeBSD. Multiple ports can share a common dependency, rather than bundling that dependency with every port or package that needs it. There are seven variables that can be used to ensure that all the required bits will be on the user's machine. There are also some pre-supported dependency variables for common cases, plus a few more to control the behavior of dependencies.
 
 [IMPORTANT]
 ====
 When software has extra dependencies that provide extra features, the base dependencies listed in `*_DEPENDS` should include the extra dependencies that would benefit most users. The base dependencies should never be a "minimal" dependency set. The goal is not to include every dependency possible. Only include those that will benefit most people.
 ====
 
 [[makefile-lib_depends]]
 === `LIB_DEPENDS`
 
 This variable specifies the shared libraries this port depends on. It is a list of `_lib:dir_` tuples where `_lib_` is the name of the shared library, `_dir_` is the directory in which to find it in case it is not available. For example,
 
 [.programlisting]
 ....
 LIB_DEPENDS=   libjpeg.so:graphics/jpeg
 ....
 
 will check for a shared jpeg library with any version, and descend into the [.filename]#graphics/jpeg# subdirectory of the ports tree to build and install it if it is not found.
 
 The dependency is checked twice, once from within the `build` target and then from within the `install` target. Also, the name of the dependency is put into the package so that `pkg install` (see man:pkg-install[8]) will automatically install it if it is not on the user's system.
 
 [[makefile-run_depends]]
 === `RUN_DEPENDS`
 
 This variable specifies executables or files this port depends on during run-time. It is a list of ``_path:dir_``[:``_target_``] tuples where `_path_` is the name of the executable or file, _dir_ is the directory in which to find it in case it is not available, and _target_ is the target to call in that directory. If _path_ starts with a slash (`/`), it is treated as a file and its existence is tested with `test -e`; otherwise, it is assumed to be an executable, and `which -s` is used to determine if the program exists in the search path.
 
 For example,
 
 [.programlisting]
 ....
 RUN_DEPENDS=	${LOCALBASE}/news/bin/innd:news/inn \
 		xmlcatmgr:textproc/xmlcatmgr
 ....
 
 will check if the file or directory [.filename]#/usr/local/news/bin/innd# exists, and build and install it from the [.filename]#news/inn# subdirectory of the ports tree if it is not found. It will also see if an executable called `xmlcatmgr` is in the search path, and descend into [.filename]#textproc/xmlcatmgr# to build and install it if it is not found.
 
 [NOTE]
 ====
 In this case, `innd` is actually an executable; if an executable is in a place that is not expected to be in the search path, use the full pathname.
 ====
 
 [NOTE]
 ====
 The official search `PATH` used on the ports build cluster is
 
 [.programlisting]
 ....
 /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin
 ....
 
 ====
 
 The dependency is checked from within the `install` target. Also, the name of the dependency is put into the package so that `pkg install` (see man:pkg-install[8]) will automatically install it if it is not on the user's system. The _target_ part can be omitted if it is the same as `DEPENDS_TARGET`.
 
 A quite common situation is when `RUN_DEPENDS` is literally the same as `BUILD_DEPENDS`, especially if ported software is written in a scripted language or if it requires the same build and run-time environment. In this case, it is both tempting and intuitive to directly assign one to the other:
 
 [.programlisting]
 ....
 RUN_DEPENDS=	${BUILD_DEPENDS}
 ....
 
 However, such assignment can pollute run-time dependencies with entries not defined in the port's original `BUILD_DEPENDS`. This happens because of man:make[1]'s lazy evaluation of variable assignment. Consider a [.filename]#Makefile# with `USE_*`, which are processed by [.filename]#ports/Mk/bsd.*.mk# to augment initial build dependencies. For example, `USES= gmake` adds package:devel/gmake[] to `BUILD_DEPENDS`. To prevent such additional dependencies from polluting `RUN_DEPENDS`, create another variable with the current content of `BUILD_DEPENDS` and assign it to both `BUILD_DEPENDS` and `RUN_DEPENDS`:
 
 [.programlisting]
 ....
 MY_DEPENDS=	some:devel/some \
 		other:lang/other
 BUILD_DEPENDS=	${MY_DEPENDS}
 RUN_DEPENDS=	${MY_DEPENDS}
 ....
 
 [IMPORTANT]
 ====
 _Do not_ use `:=` to assign `BUILD_DEPENDS` to `RUN_DEPENDS` or vice-versa. All variables are expanded immediately, which is exactly the wrong thing to do and almost always a failure.
 ====
 
 [[makefile-build_depends]]
 === `BUILD_DEPENDS`
 
 This variable specifies executables or files this port requires to build. Like `RUN_DEPENDS`, it is a list of ``_path:dir_``[:``_target_``] tuples. For example,
 
 [.programlisting]
 ....
 BUILD_DEPENDS=	unzip:archivers/unzip
 ....
 
 will check for an executable called `unzip`, and descend into the [.filename]#archivers/unzip# subdirectory of the ports tree to build and install it if it is not found.
 
 [NOTE]
 ====
 "build" here means everything from extraction to compilation. The dependency is checked from within the `extract` target. The _target_ part can be omitted if it is the same as `DEPENDS_TARGET`
 ====
 
 [[makefile-fetch_depends]]
 === `FETCH_DEPENDS`
 
 This variable specifies executables or files this port requires to fetch. Like the previous two, it is a list of ``_path:dir_``[:``_target_``] tuples. For example,
 
 [.programlisting]
 ....
 FETCH_DEPENDS=	ncftp2:net/ncftp2
 ....
 
 will check for an executable called `ncftp2`, and descend into the [.filename]#net/ncftp2# subdirectory of the ports tree to build and install it if it is not found.
 
 The dependency is checked from within the `fetch` target. The _target_ part can be omitted if it is the same as `DEPENDS_TARGET`.
 
 [[makefile-extract_depends]]
 === `EXTRACT_DEPENDS`
 
 This variable specifies executables or files this port requires for extraction. Like the previous, it is a list of ``_path:dir_``[:``_target_``] tuples. For example,
 
 [.programlisting]
 ....
 EXTRACT_DEPENDS=	unzip:archivers/unzip
 ....
 
 will check for an executable called `unzip`, and descend into the [.filename]#archivers/unzip# subdirectory of the ports tree to build and install it if it is not found.
 
 The dependency is checked from within the `extract` target. The _target_ part can be omitted if it is the same as `DEPENDS_TARGET`.
 
 [NOTE]
 ====
 Use this variable only if the extraction does not already work (the default assumes `tar`) and cannot be made to work using `USES=tar`, `USES=lha` or `USES=zip` described in crossref:uses[uses,Using `USES` Macros].
 ====
 
 [[makefile-patch_depends]]
 === `PATCH_DEPENDS`
 
 This variable specifies executables or files this port requires to patch. Like the previous, it is a list of ``_path:dir_``[:``_target_``] tuples. For example,
 
 [.programlisting]
 ....
 PATCH_DEPENDS=	${NONEXISTENT}:java/jfc:extract
 ....
 
 will descend into the [.filename]#java/jfc# subdirectory of the ports tree to extract it.
 
 The dependency is checked from within the `patch` target. The _target_ part can be omitted if it is the same as `DEPENDS_TARGET`.
 
 [[makefile-uses]]
 === `USES`
 
 Parameters can be added to define different features and dependencies used by the port. They are specified by adding this line to the [.filename]#Makefile#:
 
 [.programlisting]
 ....
 USES= feature[:arguments]
 ....
 
 For the complete list of values, please see crossref:uses[uses,Using `USES` Macros].
 
 [WARNING]
 ====
 `USES` cannot be assigned after inclusion of [.filename]#bsd.port.pre.mk#.
 ====
 
 [[makefile-use-vars]]
 === `USE_*`
 
 Several variables exist to define common dependencies shared by many ports. Their use is optional, but helps to reduce the verbosity of the port [.filename]##Makefile##s. Each of them is styled as `USE_*`. These variables may be used only in the port [.filename]##Makefile##s and [.filename]#ports/Mk/bsd.*.mk#. They are not meant for user-settable options - use `PORT_OPTIONS` for that purpose.
 
 [NOTE]
 ====
 It is _always_ incorrect to set any `USE_*` in [.filename]#/etc/make.conf#. For instance, setting
 
 [.programlisting]
 ....
 USE_GCC=X.Y
 ....
 
 (where X.Y is version number) would add a dependency on gccXY for every port, including `lang/gccXY` itself!
 ====
 
 [[makefile-use-vars-table]]
 .`USE_*`
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Means
 
 |`USE_GCC`
 a|
 
 The port requires GCC (`gcc` or `{g-plus-plus}`) to build.
 Some ports need a specific, old GCC version, some require modern, recent versions.
 It is typically set to `yes` (means always use stable, modern GCC from ports per `GCC_DEFAULT` in [.filename]#Mk/bsd.default-versions.mk#).
 This is also the default value.
 The exact version can also be specified, with a value such as `10`.
 The minimal required version can be specified as `10+`.
 GCC from the base system is used when it satisfies the requested version, otherwise an appropriate compiler is built from ports, and `CC` and `CXX` are adjusted accordingly.
 The `:build` argument following the version specifier adds only a build time dependency to the port.
 
 For example:
 [example]
 ====
 [.programlisting]
 ....
 USE_GCC=yes		# port requires a current version of GCC
 USE_GCC=11+:build	# port requires GCC 11 or later at build time only
 ....
 ====
 
 [NOTE]
 ====
 `USE_GCC=any` is deprecated and should not be used in new ports
 ====
 
 |===
 
 Variables related to gmake and [.filename]#configure# are described in crossref:special[building,Building Mechanisms], while autoconf, automake and libtool are described in crossref:special[using-autotools,Using GNU Autotools]. Perl related variables are described in crossref:special[using-perl,Using Perl]. X11 variables are listed in crossref:special[using-x11,Using X11]. crossref:special[using-gnome,Using Gnome] deals with GNOME and crossref:special[using-kde,Using KDE] with KDE related variables. crossref:special[using-java,Using Java] documents Java variables, while crossref:special[using-php,Web Applications, Apache and PHP] contains information on Apache, PHP and PEAR modules. Python is discussed in crossref:special[using-python,Using Python], while Ruby in crossref:special[using-ruby,Using Ruby]. crossref:special[using-sdl,Using SDL] provides variables used for SDL applications and finally, crossref:special[using-xfce,Using Xfce] contains information on Xfce.
 
 [[makefile-version-dependency]]
 === Minimal Version of a Dependency
 
 A minimal version of a dependency can be specified in any `*_DEPENDS` except `LIB_DEPENDS` using this syntax:
 
 [.programlisting]
 ....
 p5-Spiffy>=0.26:devel/p5-Spiffy
 ....
 
 The first field contains a dependent package name, which must match the entry in the package database, a comparison sign, and a package version. The dependency is satisfied if p5-Spiffy-0.26 or newer is installed on the machine.
 
 [[makefile-note-on-dependencies]]
 === Notes on Dependencies
 
 As mentioned above, the default target to call when a dependency is required is `DEPENDS_TARGET`. It defaults to `install`. This is a user variable; it is never defined in a port's [.filename]#Makefile#. If the port needs a special way to handle a dependency, use the `:target` part of `*_DEPENDS` instead of redefining `DEPENDS_TARGET`.
 
 When running `make clean`, the port dependencies are automatically cleaned too. If this is not desirable, define `NOCLEANDEPENDS` in the environment. This may be particularly desirable if the port has something that takes a long time to rebuild in its dependency list, such as KDE, GNOME or Mozilla.
 
 To depend on another port unconditionally, use the variable `${NONEXISTENT}` as the first field of `BUILD_DEPENDS` or `RUN_DEPENDS`. Use this only when the source of the other port is needed. Compilation time can be saved by specifying the target too. For instance
 
 [.programlisting]
 ....
 BUILD_DEPENDS=	${NONEXISTENT}:graphics/jpeg:extract
 ....
 
 will always descend to the `jpeg` port and extract it.
 
 [[makefile-circular-dependencies]]
 === Circular Dependencies Are Fatal
 
 [IMPORTANT]
 ====
 Do not introduce any circular dependencies into the ports tree!
 ====
 
 The ports building technology does not tolerate circular dependencies. If one is introduced, someone, somewhere in the world, will have their FreeBSD installation broken almost immediately, with many others quickly to follow. These can really be hard to detect. If in doubt, before making that change, make sure to run: `cd /usr/ports; make index`. That process can be quite slow on older machines, but it may be able to save a large number of people, including yourself, a lot of grief in the process.
 
 [[makefile-automatic-dependencies]]
 === Problems Caused by Automatic Dependencies
 
 Dependencies must be declared either explicitly or by using the <<makefile-options,OPTIONS framework>>. Using other methods like automatic detection complicates indexing, which causes problems for port and package management.
 
 [[makefile-automatic-dependencies-bad]]
 .Wrong Declaration of an Optional Dependency
 [example]
 ====
 
 [.programlisting]
 ....
 .include <bsd.port.pre.mk>
 
 .if exists(${LOCALBASE}/bin/foo)
 LIB_DEPENDS=	libbar.so:foo/bar
 .endif
 ....
 
 ====
 
 The problem with trying to automatically add dependencies is that files and settings outside an individual port can change at any time. For example: an index is built, then a batch of ports are installed. But one of the ports installs the tested file. The index is now incorrect, because an installed port unexpectedly has a new dependency. The index may still be wrong even after rebuilding if other ports also determine their need for dependencies based on the existence of other files.
 
 [[makefile-automatic-dependencies-good]]
 .Correct Declaration of an Optional Dependency
 [example]
 ====
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	BAR
 BAR_DESC=	Calling cellphones via bar
 
 BAR_LIB_DEPENDS=	libbar.so:foo/bar
 ....
 
 ====
 
 Testing option variables is the correct method. It will not cause inconsistencies in the index of a batch of ports, provided the options were defined prior to the index build. Simple scripts can then be used to automate the building, installation, and updating of these ports and their packages.
 
 [[makefile-masterdir]]
 == Slave Ports and `MASTERDIR`
 
 If the port needs to build slightly different versions of packages by having a variable (for instance, resolution, or paper size) take different values, create one subdirectory per package to make it easier for users to see what to do, but try to share as many files as possible between ports. Typically, by using variables cleverly, only a very short [.filename]#Makefile# is needed in all but one of the directories. In the sole [.filename]#Makefile#, use `MASTERDIR` to specify the directory where the rest of the files are. Also, use a variable as part of <<porting-pkgname,`PKGNAMESUFFIX`>> so the packages will have different names.
 
 This will be best demonstrated by an example. This is part of [.filename]#print/pkfonts300/Makefile#;
 
 [.programlisting]
 ....
 PORTNAME=	pkfonts${RESOLUTION}
 PORTVERSION=	1.0
 DISTFILES=	pk${RESOLUTION}.tar.gz
 
 PLIST=		${PKGDIR}/pkg-plist.${RESOLUTION}
 
 .if !defined(RESOLUTION)
 RESOLUTION=	300
 .else
 .if ${RESOLUTION} != 118 && ${RESOLUTION} != 240 && \
 	${RESOLUTION} != 300 && ${RESOLUTION} != 360 && \
 	${RESOLUTION} != 400 && ${RESOLUTION} != 600
 .BEGIN:
 	@${ECHO_MSG} "Error: invalid value for RESOLUTION: \"${RESOLUTION}\""
 	@${ECHO_MSG} "Possible values are: 118, 240, 300, 360, 400 and 600."
 	@${FALSE}
 .endif
 .endif
 ....
 
 package:print/pkfonts300[] also has all the regular patches, package files, etc. Running `make` there, it will take the default value for the resolution (300) and build the port normally.
 
 As for other resolutions, this is the _entire_ [.filename]#print/pkfonts360/Makefile#:
 
 [.programlisting]
 ....
 RESOLUTION=	360
 MASTERDIR=	${.CURDIR}/../pkfonts300
 
 .include	"${MASTERDIR}/Makefile"
 ....
 
 ([.filename]#print/pkfonts118/Makefile#, [.filename]#print/pkfonts600/Makefile#, and all the other are similar). `MASTERDIR` definition tells [.filename]#bsd.port.mk# that the regular set of subdirectories like `FILESDIR` and `SCRIPTDIR` are to be found under [.filename]#pkfonts300#. The `RESOLUTION=360` line will override the `RESOLUTION=300` line in [.filename]#pkfonts300/Makefile# and the port will be built with resolution set to 360.
 
 [[makefile-manpages]]
 == Man Pages
 
 If the port anchors its man tree somewhere other than `PREFIX`, use `MANDIRS` to specify those directories. Note that the files corresponding to manual pages must be placed in [.filename]#pkg-plist# along with the rest of the files. The purpose of `MANDIRS` is to enable automatic compression of manual pages, therefore the file names are suffixed with [.filename]#.gz#.
 
 [[makefile-info]]
 == Info Files
 
 If the package needs to install GNU info files, list them in `INFO` (without the trailing `.info`), one entry per document. These files are assumed to be installed to [.filename]#PREFIX/INFO_PATH#. Change `INFO_PATH` if the package uses a different location. However, this is not recommended. These entries contain just the path relative to [.filename]#PREFIX/INFO_PATH#. For example, package:lang/gcc34[] installs info files to [.filename]#PREFIX/INFO_PATH/gcc34#, and `INFO` will be something like this:
 
 [.programlisting]
 ....
 INFO=	gcc34/cpp gcc34/cppinternals gcc34/g77 ...
 ....
 
 Appropriate installation/de-installation code will be automatically added to the temporary [.filename]#pkg-plist# before package registration.
 
 [[makefile-options]]
 == Makefile Options
 
 Many applications can be built with optional or differing configurations. Examples include choice of natural (human) language, GUI versus command-line, or type of database to support. Users may need a different configuration than the default, so the ports system provides hooks the port author can use to control which variant will be built. Supporting these options properly will make users happy, and effectively provide two or more ports for the price of one.
 
 [[makefile-options-options]]
 === `OPTIONS`
 
 [[makefile-options-background]]
 ==== Background
 
 `OPTIONS_*` give the user installing the port a dialog showing the available options, and then saves those options to [.filename]#${PORT_DBDIR}/${OPTIONS_NAME}/options#. The next time the port is built, the options are reused. `PORT_DBDIR` defaults to [.filename]#/var/db/ports#. `OPTIONS_NAME` is to the port origin with an underscore as the space separator, for example, for package:dns/bind99[] it will be `dns_bind99`.
 
 When the user runs `make config` (or runs `make build` for the first time), the framework checks for [.filename]#${PORT_DBDIR}/${OPTIONS_NAME}/options#. If that file does not exist, the values of `OPTIONS_*` are used, and a dialog box is displayed where the options can be enabled or disabled. Then [.filename]#options# is saved and the configured variables are used when building the port.
 
 If a new version of the port adds new `OPTIONS`, the dialog will be presented to the user with the saved values of old `OPTIONS` prefilled.
 
 `make showconfig` shows the saved configuration. Use `make rmconfig` to remove the saved configuration.
 
 [[makefile-options-syntax]]
 ==== Syntax
 
 `OPTIONS_DEFINE` contains a list of `OPTIONS` to be used. These are independent of each other and are not grouped:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 ....
 
 Once defined, `OPTIONS` are described (optional, but strongly recommended):
 
 [.programlisting]
 ....
 OPT1_DESC=	Describe OPT1
 OPT2_DESC=	Describe OPT2
 OPT3_DESC=	Describe OPT3
 OPT4_DESC=	Describe OPT4
 OPT5_DESC=	Describe OPT5
 OPT6_DESC=	Describe OPT6
 ....
 
 [.filename]#ports/Mk/bsd.options.desc.mk# has descriptions for many common `OPTIONS`. While often useful, override them if the description is insufficient for the port.
 
 [TIP]
 ====
 
 When describing options, view it from the perspective of the user: "What functionality does it change?" and "Why would I want to enable this?" Do not just repeat the name. For example, describing the `NLS` option as "include NLS support" does not help the user, who can already see the option name but may not know what it means. Describing it as "Native Language Support via gettext utilities" is much more helpful.
 ====
 
 [IMPORTANT]
 ====
 Option names are always in all uppercase. They cannot use mixed case or lowercase.
 ====
 
 `OPTIONS` can be grouped as radio choices, where only one choice from each group is allowed:
 
 [.programlisting]
 ....
 OPTIONS_SINGLE=		SG1
 OPTIONS_SINGLE_SG1=	OPT3 OPT4
 ....
 
 [WARNING]
 ====
 
 There _must_ be one of each `OPTIONS_SINGLE` group selected at all times for the options to be valid. One option of each group _must_ be added to `OPTIONS_DEFAULT`.
 ====
 
 `OPTIONS` can be grouped as radio choices, where none or only one choice from each group is allowed:
 
 [.programlisting]
 ....
 OPTIONS_RADIO=		RG1
 OPTIONS_RADIO_RG1=	OPT7 OPT8
 ....
 
 `OPTIONS` can also be grouped as "multiple-choice" lists, where _at least one_ option must be enabled:
 
 [.programlisting]
 ....
 OPTIONS_MULTI=		MG1
 OPTIONS_MULTI_MG1=	OPT5 OPT6
 ....
 
 `OPTIONS` can also be grouped as "multiple-choice" lists, where none or any option can be enabled:
 
 [.programlisting]
 ....
 OPTIONS_GROUP=		GG1
 OPTIONS_GROUP_GG1=	OPT9 OPT10
 ....
 
 `OPTIONS` are unset by default, unless they are listed in `OPTIONS_DEFAULT`:
 
 [.programlisting]
 ....
 OPTIONS_DEFAULT=	OPT1 OPT3 OPT6
 ....
 
 `OPTIONS` definitions must appear before the inclusion of [.filename]#bsd.port.options.mk#. `PORT_OPTIONS` values can only be tested after the inclusion of [.filename]#bsd.port.options.mk#. Inclusion of [.filename]#bsd.port.pre.mk# can be used instead, too, and is still widely used in ports written before the introduction of [.filename]#bsd.port.options.mk#. But be aware that some variables will not work as expected after the inclusion of [.filename]#bsd.port.pre.mk#, typically some `USE_*` flags.
 
 [[ports-options-simple-use]]
 .Simple Use of `OPTIONS`
 [example]
 ====
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	FOO BAR
 OPTIONS_DEFAULT=FOO
 
 FOO_DESC=	Option foo support
 BAR_DESC=	Feature bar support
 
 # Will add --with-foo / --without-foo
 FOO_CONFIGURE_WITH=	foo
 BAR_RUN_DEPENDS=	bar:bar/bar
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 [[ports-options-check-unset]]
 .Check for Unset Port `OPTIONS`
 [example]
 ====
 
 [.programlisting]
 ....
 .if ! ${PORT_OPTIONS:MEXAMPLES}
 CONFIGURE_ARGS+=--without-examples
 .endif
 ....
 
 The form shown above is discouraged. The preferred method is using a configure knob to really enable and disable the feature to match the option:
 
 [.programlisting]
 ....
 # Will add --with-examples / --without-examples
 EXAMPLES_CONFIGURE_WITH=	examples
 ....
 
 ====
 
 [[ports-options-practical-use]]
 .Practical Use of `OPTIONS`
 [example]
 ====
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=		EXAMPLES
 OPTIONS_DEFAULT=	PGSQL LDAP SSL
 
 OPTIONS_SINGLE=		BACKEND
 OPTIONS_SINGLE_BACKEND=	MYSQL PGSQL BDB
 
 OPTIONS_MULTI=		AUTH
 OPTIONS_MULTI_AUTH=	LDAP PAM SSL
 
 EXAMPLES_DESC=		Install extra examples
 MYSQL_DESC=		Use MySQL as backend
 PGSQL_DESC=		Use PostgreSQL as backend
 BDB_DESC=		Use Berkeley DB as backend
 LDAP_DESC=		Build with LDAP authentication support
 PAM_DESC=		Build with PAM support
 SSL_DESC=		Build with OpenSSL support
 
 # Will add USE_PGSQL=yes
 PGSQL_USE=	pgsql=yes
 # Will add --enable-postgres / --disable-postgres
 PGSQL_CONFIGURE_ENABLE=	postgres
 
 ICU_LIB_DEPENDS=	libicuuc.so:devel/icu
 
 # Will add --with-examples / --without-examples
 EXAMPLES_CONFIGURE_WITH=	examples
 
 # Check other OPTIONS
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 [[makefile-options-default]]
 ==== Default Options
 
 These options are always on by default.
 
 * `DOCS` - build and install documentation.
 * `NLS` - Native Language Support.
 * `EXAMPLES` - build and install examples.
 * `IPV6` - IPv6 protocol support.
 
 [NOTE]
 ====
 There is no need to add these to `OPTIONS_DEFAULT`. To have them active, and show up in the options selection dialog, however, they must be added to `OPTIONS_DEFINE`.
 ====
 
 [[makefile-options-auto-activation]]
 === Feature Auto-Activation
 
 When using a GNU configure script, keep an eye on which optional features are activated by auto-detection. Explicitly disable optional features that are not needed by adding `--without-xxx` or `--disable-xxx` in `CONFIGURE_ARGS`.
 
 [[makefile-options-auto-activation-bad]]
 .Wrong Handling of an Option
 [example]
 ====
 
 [.programlisting]
 ....
 .if ${PORT_OPTIONS:MFOO}
 LIB_DEPENDS+=		libfoo.so:devel/foo
 CONFIGURE_ARGS+=	--enable-foo
 .endif
 ....
 
 ====
 
 In the example above, imagine a library libfoo is installed on the system. The user does not want this application to use libfoo, so he toggled the option off in the `make config` dialog. But the application's configure script detects the library present in the system and includes its support in the resulting executable. Now when the user decides to remove libfoo from the system, the ports system does not protest (no dependency on libfoo was recorded) but the application breaks.
 
 [[makefile-options-auto-activation-good]]
 .Correct Handling of an Option
 [example]
 ====
 
 [.programlisting]
 ....
 FOO_LIB_DEPENDS=		libfoo.so:devel/foo
 # Will add --enable-foo / --disable-foo
 FOO_CONFIGURE_ENABLE=	foo
 ....
 
 ====
 
 [NOTE]
 ====
 Under some circumstances, the shorthand conditional syntax can cause problems with complex constructs. The errors are usually `Malformed conditional`, an alternative syntax can be used.
 
 [.programlisting]
 ....
 .if !empty(VARIABLE:MVALUE)
 ....
 
 as an alternative to
 
 [.programlisting]
 ....
 .if ${VARIABLE:MVALUE}
 ....
 
 ====
 
 [[options-helpers]]
 === Options Helpers
 
 There are some macros to help simplify conditional values which differ based on the options set. For easier access, a comprehensive list is provided:
 
 `PLIST_SUB`, `SUB_LIST`::
 For automatic `%%_OPT_%%` and `%%NO__OPT__%%` generation, see <<options_sub>>.
 +
 For more complex usage, see <<options-variables>>.
 
 `CONFIGURE_ARGS`::
 For `--enable-_x_` and `--disable-_x_`, see <<options-configure_enable>>.
 +
 For `--with-_x_` and `--without-_x_`, see <<options-configure_with>>.
 +
 For all other cases, see <<options-configure_on>>.
 
 `CMAKE_ARGS`::
 For arguments that are booleans (`on`, `off`, `true`, `false`, `0`, `1`) see <<options-cmake_bool>>.
 +
 For all other cases, see <<options-cmake_on>>.
 
 `MESON_ARGS`::
 For arguments that take `true` or `false`, see <<options-meson_true>>.
 +
 For arguments that take `yes` or `no`, use <<options-meson_yes>>.
 +
 For arguments that take `enabled` or `disabled`, see <<options-meson_enabled>>.
 +
 For all other cases, use <<options-meson_on>>.
 
 `QMAKE_ARGS`::
 See <<options-qmake_on>>.
 
 `USE_*`::
 See <<options-use>>.
 
 `*_DEPENDS`::
 See <<options-dependencies>>.
 
 `*` (Any variable)::
 The most used variables have direct helpers, see <<options-variables>>.
 +
 For any variable without a specific helper, see <<options-vars>>.
 
 Options dependencies::
 When an option need another option to work, see <<options-implies>>.
 
 Options conflicts::
 When an option cannot work if another is also enabled, see <<options-prevents>>.
 
 Build targets::
 When an option need some extra processing, see <<options-targets>>.
 
 [[options_sub]]
 ==== `OPTIONS_SUB`
 
 If `OPTIONS_SUB` is set to `yes` then each of the options added to `OPTIONS_DEFINE` will be added to `PLIST_SUB` and `SUB_LIST`, for example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPTIONS_SUB=	yes
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 PLIST_SUB+=	OPT1="" NO_OPT1="@comment "
 SUB_LIST+=	OPT1="" NO_OPT1="@comment "
 .else
 PLIST_SUB+=	OPT1="@comment " NO_OPT1=""
 SUB_LIST+=	OPT1="@comment " NO_OPT1=""
 .endif
 ....
 
 [NOTE]
 ====
 The value of `OPTIONS_SUB` is ignored. Setting it to any value will add `PLIST_SUB` and `SUB_LIST` entries for _all_ options.
 ====
 
 [[options-use]]
 ==== `OPT_USE` and `OPT_USE_OFF`
 
 When option _OPT_ is selected, for each `_key=value_` pair in ``OPT_USE``, _value_ is appended to the corresponding `USE_KEY`. If _value_ has spaces in it, replace them with commas and they will be changed back to spaces during processing. `OPT_USE_OFF` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_USES=	xorg
 OPT1_USE=	mysql=yes xorg=x11,xextproto,xext,xrandr
 OPT1_USE_OFF=	openssl=yes
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 USE_MYSQL=	yes
 USES+=		xorg
 USE_XORG=	x11 xextproto xext xrandr
 .else
 USE_OPENSSL=	yes
 .endif
 ....
 
 [[options-configure-helpers]]
 ==== `CONFIGURE_ARGS` Helpers
 
 [[options-configure_enable]]
 ===== `OPT_CONFIGURE_ENABLE`
 
 When option _OPT_ is selected, for each _entry_ in `OPT_CONFIGURE_ENABLE` then `--enable-_entry_` is appended to `CONFIGURE_ARGS`. When option _OPT_ is _not_ selected, `--disable-_entry_` is appended to `CONFIGURE_ARGS`. An optional argument can be specified with an `=` symbol. This argument is only appended to the `--enable-_entry_` configure option. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 OPT1_CONFIGURE_ENABLE=	test1 test2
 OPT2_CONFIGURE_ENABLE=	test2=exhaustive
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 CONFIGURE_ARGS+=	--enable-test1 --enable-test2
 .else
 CONFIGURE_ARGS+=	--disable-test1 --disable-test2
 .endif
 
 .if ${PORT_OPTIONS:MOPT2}
 CONFIGURE_ARGS+=	--enable-test2=exhaustive
 .else
 CONFIGURE_ARGS+=	--disable-test2
 .endif
 ....
 
 [[options-configure_with]]
 ===== `OPT_CONFIGURE_WITH`
 
 When option _OPT_ is selected, for each _entry_ in `_OPT_CONFIGURE_WITH` then `--with-_entry_` is appended to `CONFIGURE_ARGS`. When option _OPT_ is _not_ selected, `--without-_entry_` is appended to `CONFIGURE_ARGS`. An optional argument can be specified with an `=` symbol. This argument is only appended to the `--with-_entry_` configure option. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 OPT1_CONFIGURE_WITH=	test1
 OPT2_CONFIGURE_WITH=	test2=exhaustive
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 CONFIGURE_ARGS+=	--with-test1
 .else
 CONFIGURE_ARGS+=	--without-test1
 .endif
 
 .if ${PORT_OPTIONS:MOPT2}
 CONFIGURE_ARGS+=	--with-test2=exhaustive
 .else
 CONFIGURE_ARGS+=	--without-test2
 .endif
 ....
 
 [[options-configure_on]]
 ===== `OPT_CONFIGURE_ON` and `OPT_CONFIGURE_OFF`
 
 When option _OPT_ is selected, the value of `OPT_CONFIGURE_ON`, if defined, is appended to `CONFIGURE_ARGS`. `OPT_CONFIGURE_OFF` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_CONFIGURE_ON=	--add-test
 OPT1_CONFIGURE_OFF=	--no-test
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 CONFIGURE_ARGS+=	--add-test
 .else
 CONFIGURE_ARGS+=	--no-test
 .endif
 ....
 
 [TIP]
 ====
 
 Most of the time, the helpers in <<options-configure_enable>> and <<options-configure_with>> provide a shorter and more comprehensive functionality.
 ====
 
 [[options-cmake-helpers]]
 ==== `CMAKE_ARGS` Helpers
 
 [[options-cmake_on]]
 ===== `OPT_CMAKE_ON` and `OPT_CMAKE_OFF`
 
 When option _OPT_ is selected, the value of `OPT_CMAKE_ON`, if defined, is appended to `CMAKE_ARGS`. `OPT_CMAKE_OFF` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_CMAKE_ON=	-DTEST:BOOL=true -DDEBUG:BOOL=true
 OPT1_CMAKE_OFF=	-DOPTIMIZE:BOOL=true
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 CMAKE_ARGS+=	-DTEST:BOOL=true -DDEBUG:BOOL=true
 .else
 CMAKE_ARGS+=	-DOPTIMIZE:BOOL=true
 .endif
 ....
 
 [TIP]
 ====
 
 See <<options-cmake_bool>> for a shorter helper when the value is boolean.
 ====
 
 [[options-cmake_bool]]
 ===== `OPT_CMAKE_BOOL` and `OPT_CMAKE_BOOL_OFF`
 
 When option _OPT_ is selected, for each _entry_ in `OPT_CMAKE_BOOL` then `-D_entry_:BOOL=true` is appended to `CMAKE_ARGS`. When option _OPT_ is _not_ selected, `-D_entry_:BOOL=false` is appended to `CONFIGURE_ARGS`. `OPT_CMAKE_BOOL_OFF` is the opposite, `-D_entry_:BOOL=false` is appended to `CMAKE_ARGS` when the option is selected, and `-D_entry_:BOOL=true` when the option is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_CMAKE_BOOL=	TEST DEBUG
 OPT1_CMAKE_BOOL_OFF=	OPTIMIZE
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 CMAKE_ARGS+=	-DTEST:BOOL=true -DDEBUG:BOOL=true \
 		-DOPTIMIZE:BOOL=false
 .else
 CMAKE_ARGS+=	-DTEST:BOOL=false -DDEBUG:BOOL=false \
 		-DOPTIMIZE:BOOL=true
 .endif
 ....
 
 [[options-meson-helpers]]
 ==== `MESON_ARGS` Helpers
 
 [[options-meson_on]]
 ===== `OPT_MESON_ON` and `OPT_MESON_OFF`
 
 When option _OPT_ is selected, the value of `OPT_MESON_ON`, if defined, is appended to `MESON_ARGS`. `OPT_MESON_OFF` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_MESON_ON=	-Dopt=1
 OPT1_MESON_OFF=	-Dopt=2
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 MESON_ARGS+=	-Dopt=1
 .else
 MESON_ARGS+=	-Dopt=2
 .endif
 ....
 
 [[options-meson_true]]
 ===== `OPT_MESON_TRUE` and `OPT_MESON_FALSE`
 
 When option _OPT_ is selected, for each _entry_ in `OPT_MESON_TRUE` then `-D_entry_=true` is appended to `MESON_ARGS`. When option _OPT_ is _not_ selected, `-D_entry_=false` is appended to `MESON_ARGS`. `OPT_MESON_FALSE` is the opposite, `-D_entry_=false` is appended to `MESON_ARGS` when the option is selected, and `-D_entry_=true` when the option is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_MESON_TRUE=	test debug
 OPT1_MESON_FALSE=	optimize
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 MESON_ARGS+=	-Dtest=true -Ddebug=true \
 		-Doptimize=false
 .else
 MESON_ARGS+=	-Dtest=false -Ddebug=false \
 		-Doptimize=true
 .endif
 ....
 
 [[options-meson_yes]]
 ===== `OPT_MESON_YES` and `OPT_MESON_NO`
 
 When option _OPT_ is selected, for each _entry_ in `OPT_MESON_YES` then `-D_entry_=yes` is appended to `MESON_ARGS`. When option _OPT_ is _not_ selected, `-D_entry_=no` is appended to `MESON_ARGS`. `OPT_MESON_NO` is the opposite, `-D_entry_=no` is appended to `MESON_ARGS` when the option is selected, and `-D_entry_=yes` when the option is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_MESON_YES=	test debug
 OPT1_MESON_NO=	optimize
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 MESON_ARGS+=	-Dtest=yes -Ddebug=yes \
 		-Doptimize=no
 .else
 MESON_ARGS+=	-Dtest=no -Ddebug=no \
 		-Doptimize=yes
 .endif
 ....
 
 [[options-meson_enabled]]
 ===== `OPT_MESON_ENABLED` and `OPT_MESON_DISABLED`
 
 When option _OPT_ is selected, for each _entry_ in `OPT_MESON_ENABLED` then `-D_entry_=enabled` is appended to `MESON_ARGS`. When option _OPT_ is _not_ selected, `-D_entry_=disabled` is appended to `MESON_ARGS`. `OPT_MESON_DISABLED` is the opposite, `-D_entry_=disabled` is appended to `MESON_ARGS` when the option is selected, and `-D_entry_=enabled` when the option is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_MESON_ENABLED=	test
 OPT1_MESON_DISABLED=	debug
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 MESON_ARGS+=	-Dtest=enabled -Ddebug=disabled
 .else
 MESON_ARGS+=	-Dtest=disabled -Ddebug=enabled
 .endif
 ....
 
 [[options-qmake_on]]
 ==== `OPT_QMAKE_ON` and `OPT_QMAKE_OFF`
 
 When option _OPT_ is selected, the value of `OPT_QMAKE_ON`, if defined, is appended to `QMAKE_ARGS`. `OPT_QMAKE_OFF` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_QMAKE_ON=	-DTEST:BOOL=true
 OPT1_QMAKE_OFF=	-DPRODUCTION:BOOL=true
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 QMAKE_ARGS+=	-DTEST:BOOL=true
 .else
 QMAKE_ARGS+=	-DPRODUCTION:BOOL=true
 .endif
 ....
 
 [[options-implies]]
 ==== `OPT_IMPLIES`
 
 Provides a way to add dependencies between options.
 
 When _OPT_ is selected, all the options listed in this variable will be selected too. Using the <<options-configure_enable,`OPT_CONFIGURE_ENABLE`>> described earlier to illustrate:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 OPT1_IMPLIES=	OPT2
 
 OPT1_CONFIGURE_ENABLE=	opt1
 OPT2_CONFIGURE_ENABLE=	opt2
 ....
 
 Is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 CONFIGURE_ARGS+=	--enable-opt1
 .else
 CONFIGURE_ARGS+=	--disable-opt1
 .endif
 
 .if ${PORT_OPTIONS:MOPT2} || ${PORT_OPTIONS:MOPT1}
 CONFIGURE_ARGS+=	--enable-opt2
 .else
 CONFIGURE_ARGS+=	--disable-opt2
 .endif
 ....
 
 [[options-implies-ex1]]
 .Simple Use of `OPT_IMPLIES`
 [example]
 ====
 
 This port has a `X11` option, and a `GNOME` option that needs the `X11` option to be selected to build.
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	X11 GNOME
 OPTIONS_DEFAULT=	X11
 
 X11_USES=	xorg
 X11_USE=	xorg=xi,xextproto
 GNOME_USE=	gnome=gtk30
 GNOME_IMPLIES=	X11
 ....
 
 ====
 
 [[options-prevents]]
 ==== `OPT_PREVENTS` and `OPT_PREVENTS_MSG`
 
 Provides a way to add conflicts between options.
 
 When _OPT_ is selected, all the options listed in `OPT_PREVENTS` must be un-selected. If `OPT_PREVENTS_MSG` is set and a conflict is triggered, its content will be shown explaining why they conflict. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 OPT1_PREVENTS=	OPT2
 OPT1_PREVENTS_MSG=	OPT1 and OPT2 enable conflicting options
 ....
 
 Is roughly equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT2} && ${PORT_OPTIONS:MOPT1}
 BROKEN=	Option OPT1 conflicts with OPT2 (select only one)
 .endif
 ....
 
 The only difference is that the first one will write an error after running `make config`, suggesting changing the selected options.
 
 [[options-prevents-ex1]]
 .Simple Use of `OPT_PREVENTS`
 [example]
 ====
 
 This port has `X509` and `SCTP` options. Both options add patches, but the patches conflict with each other, so they cannot be selected at the same time.
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	X509 SCTP
 
 SCTP_PATCHFILES=	${PORTNAME}-6.8p1-sctp-2573.patch.gz:-p1
 SCTP_CONFIGURE_WITH=	sctp
 
 X509_PATCH_SITES=	http://www.roumenpetrov.info/openssh/x509/:x509
 X509_PATCHFILES=	${PORTNAME}-7.0p1+x509-8.5.diff.gz:-p1:x509
 X509_PREVENTS=		SCTP
 X509_PREVENTS_MSG=	X509 and SCTP patches conflict
 ....
 
 ====
 
 [[options-vars]]
 ==== `OPT_VARS` and `OPT_VARS_OFF`
 
 Provides a generic way to set and append to variables.
 
 [WARNING]
 ====
 
 Before using `OPT_VARS` and `OPT_VARS_OFF`, see if there is already a more specific helper available in <<options-variables>>.
 ====
 
 When option _OPT_ is selected, and `OPT_VARS` defined, `_key_=_value_` and `_key_+=_value_` pairs are evaluated from `OPT_VARS`. An `=` cause the existing value of `KEY` to be overwritten, an `+=` appends to the value. `OPT_VARS_OFF` works the same way, but when `OPT` is _not_ selected.
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2 OPT3
 OPT1_VARS=	also_build+=bin1
 OPT2_VARS=	also_build+=bin2
 OPT3_VARS=	bin3_build=yes
 OPT3_VARS_OFF=	bin3_build=no
 
 MAKE_ARGS=	ALSO_BUILD="${ALSO_BUILD}" BIN3_BUILD="${BIN3_BUILD}"
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1 OPT2
 
 MAKE_ARGS=	ALSO_BUILD="${ALSO_BUILD}" BIN3_BUILD="${BIN3_BUILD}"
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 ALSO_BUILD+=	bin1
 .endif
 
 .if ${PORT_OPTIONS:MOPT2}
 ALSO_BUILD+=	bin2
 .endif
 
 .if ${PORT_OPTIONS:MOPT2}
 BIN3_BUILD=	yes
 .else
 BIN3_BUILD=	no
 .endif
 ....
 
 [IMPORTANT]
 ====
 Values containing whitespace must be enclosed in quotes:
 
 [.programlisting]
 ....
 OPT_VARS=	foo="bar baz"
 ....
 
 This is due to the way man:make[1] variable expansion deals with whitespace. When `OPT_VARS= foo=bar baz` is expanded, the variable ends up containing two strings, `foo=bar` and `baz`. But the submitter probably intended there to be only one string, `foo=bar baz`. Quoting the value prevents whitespace from being used as a delimiter.
 
 Also, _do not_ add extra spaces after the `_var_=` sign and before the value, it would also be split into two strings. _This will not work_:
 
 [.programlisting]
 ....
 OPT_VARS=	foo=	bar
 ....
 
 ====
 
 [[options-dependencies]]
 ==== Dependencies, `OPT_DEPTYPE` and `OPT_DEPTYPE_OFF`
 
 For any of these dependency types:
 
 * `PKG_DEPENDS`
 * `EXTRACT_DEPENDS`
 * `PATCH_DEPENDS`
 * `FETCH_DEPENDS`
 * `BUILD_DEPENDS`
 * `LIB_DEPENDS`
 * `RUN_DEPENDS`
 
 When option _OPT_ is selected, the value of `OPT_DEPTYPE`, if defined, is appended to `DEPTYPE`. `OPT_DEPTYPE_OFF` works the same, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_LIB_DEPENDS=	liba.so:devel/a
 OPT1_LIB_DEPENDS_OFF=	libb.so:devel/b
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 LIB_DEPENDS+=	liba.so:devel/a
 .else
 LIB_DEPENDS+=	libb.so:devel/b
 .endif
 ....
 
 [[options-variables]]
 ==== Generic Variables Replacement, `OPT_VARIABLE` and `OPT_VARIABLE_OFF`
 
 For any of these variables:
 
 * `ALL_TARGET`
 * `BINARY_ALIAS`
 * `BROKEN`
 * `CATEGORIES`
 * `CFLAGS`
 * `CONFIGURE_ENV`
 * `CONFLICTS`
 * `CONFLICTS_BUILD`
 * `CONFLICTS_INSTALL`
 * `CPPFLAGS`
 * `CXXFLAGS`
 * `DESKTOP_ENTRIES`
 * `DISTFILES`
 * `EXTRACT_ONLY`
 * `EXTRA_PATCHES`
 * `GH_ACCOUNT`
 * `GH_PROJECT`
 * `GH_SUBDIR`
 * `GH_TAGNAME`
 * `GH_TUPLE`
 * `GL_ACCOUNT`
 * `GL_COMMIT`
 * `GL_PROJECT`
 * `GL_SITE`
 * `GL_SUBDIR`
 * `GL_TUPLE`
 * `IGNORE`
 * `INFO`
 * `INSTALL_TARGET`
 * `LDFLAGS`
 * `LIBS`
 * `MAKE_ARGS`
 * `MAKE_ENV`
 * `MASTER_SITES`
 * `PATCHFILES`
 * `PATCH_SITES`
 * `PLIST_DIRS`
 * `PLIST_FILES`
 * `PLIST_SUB`
 * `PORTDOCS`
 * `PORTEXAMPLES`
 * `SUB_FILES`
 * `SUB_LIST`
 * `TEST_TARGET`
 * `USES`
 
 When option _OPT_ is selected, the value of `OPT_ABOVEVARIABLE`, if defined, is appended to `_ABOVEVARIABLE_`. `OPT_ABOVEVARIABLE_OFF` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 OPT1_USES=	gmake
 OPT1_CFLAGS_OFF=	-DTEST
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MOPT1}
 USES+=		gmake
 .else
 CFLAGS+=	-DTEST
 .endif
 ....
 
 [NOTE]
 ====
 Some variables are not in this list, in particular `PKGNAMEPREFIX` and `PKGNAMESUFFIX`. This is intentional. A port _must not_ change its name when its option set changes.
 ====
 
 [WARNING]
 ====
 
 Some of these variables, at least `ALL_TARGET`, `DISTFILES` and `INSTALL_TARGET`, have their default values set _after_ the options are processed.
 
 With these lines in the [.filename]#Makefile#:
 
 [.programlisting]
 ....
 ALL_TARGET=	all
 
 DOCS_ALL_TARGET=	doc
 ....
 
 If the `DOCS` option is enabled, `ALL_TARGET` will have a final value of `all doc`; if the option is disabled, it would have a value of `all`.
 
 With only the options helper line in the [.filename]#Makefile#:
 
 [.programlisting]
 ....
 DOCS_ALL_TARGET=	doc
 ....
 
 If the `DOCS` option is enabled, `ALL_TARGET` will have a final value of `doc`; if the option is disabled, it would have a value of `all`.
 ====
 
 [[options-targets]]
 ==== Additional Build Targets, `_target_-_OPT_-on` and `_target_-_OPT_-off`
 
 These [.filename]#Makefile# targets can accept optional extra build targets:
 
 * `pre-fetch`
 * `do-fetch`
 * `post-fetch`
 * `pre-extract`
 * `do-extract`
 * `post-extract`
 * `pre-patch`
 * `do-patch`
 * `post-patch`
 * `pre-configure`
 * `do-configure`
 * `post-configure`
 * `pre-build`
 * `do-build`
 * `post-build`
 * `pre-install`
 * `do-install`
 * `post-install`
 * `post-stage`
 * `pre-package`
 * `do-package`
 * `post-package`
 
 When option _OPT_ is selected, the target `_TARGET_-_OPT_-on`, if defined, is executed after `_TARGET_`. `_TARGET_-_OPT_-off` works the same way, but when `OPT` is _not_ selected. For example:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 post-patch-OPT1-on:
 	@${REINPLACE_CMD} -e '/opt1/s|/usr/bin/|${EXAMPLESDIR}/|' ${WRKSRC}/Makefile
 
 post-patch-OPT1-off:
 	@${REINPLACE_CMD} -e '/opt1/s|/usr/bin/|${PREFIX}/bin/|' ${WRKSRC}/Makefile
 ....
 
 is equivalent to:
 
 [.programlisting]
 ....
 OPTIONS_DEFINE=	OPT1
 
 .include <bsd.port.options.mk>
 
 post-patch:
 .if ${PORT_OPTIONS:MOPT1}
 	@${REINPLACE_CMD} -e '/opt1/s|/usr/bin/|${EXAMPLESDIR}/|' ${WRKSRC}/Makefile
 .else
 	@${REINPLACE_CMD} -e '/opt1/s|/usr/bin/|${PREFIX}/bin/|' ${WRKSRC}/Makefile
 .endif
 ....
 
 [[makefile-wrkdir]]
 == Specifying the Working Directory
 
 Each port is extracted into a working directory, which must be writable. The ports system defaults to having `DISTFILES` unpack in to a directory called `${DISTNAME}`. In other words, if the [.filename]#Makefile# has:
 
 [.programlisting]
 ....
 PORTNAME=	foo
 DISTVERSION=	1.0
 ....
 
 then the port's distribution files contain a top-level directory, [.filename]#foo-1.0#, and the rest of the files are located under that directory.
 
 A number of variables can be overridden if that is not the case.
 
 [[makefile-wrksrc]]
 === `WRKSRC`
 
 The variable lists the name of the directory that is created when the application's distfiles are extracted. If our previous example extracted into a directory called [.filename]#foo# (and not [.filename]#foo-1.0#) write:
 
 [.programlisting]
 ....
 WRKSRC=	${WRKDIR}/foo
 ....
 
 or possibly
 
 [.programlisting]
 ....
 WRKSRC=	${WRKDIR}/${PORTNAME}
 ....
 
 [[makefile-wrksrc_subdir]]
 === `WRKSRC_SUBDIR`
 
 If the source files needed for the port are in a subdirectory of the extracted distribution file, set `WRKSRC_SUBDIR` to that directory.
 
 [.programlisting]
 ....
 WRKSRC_SUBDIR=	src
 ....
 
 [[makefile-no_wrksubdir]]
 === `NO_WRKSUBDIR`
 
 If the port does not extract in to a subdirectory at all, then set `NO_WRKSUBDIR` to indicate that.
 
 [.programlisting]
 ....
 NO_WRKSUBDIR=	yes
 ....
 
 [NOTE]
 ====
 Because `WRKDIR` is the only directory that is supposed to be writable during the build, and is used to store many files recording the status of the build, the port's extraction will be forced into a subdirectory.
 ====
 
 [[conflicts]]
 == Conflict Handling
 
 There are three different variables to register a conflict between packages and ports: `CONFLICTS`, `CONFLICTS_INSTALL` and `CONFLICTS_BUILD`.
 
 [NOTE]
 ====
 The conflict variables automatically set the variable `IGNORE`, which is more fully documented in crossref:porting-dads[dads-noinstall,Marking a Port Not Installable with `BROKEN`, `FORBIDDEN`, or `IGNORE`].
 ====
 
 When removing one of several conflicting ports, it is advisable to retain `CONFLICTS` in those other ports for a few months to cater for users who only update once in a while.
 
 [[conclicts-conflicts_install]]
 `CONFLICTS_INSTALL`::
 If the package cannot coexist with other packages (because of file conflicts, runtime incompatibilities, etc.). `CONFLICTS_INSTALL` check is done after the build stage and prior to the install stage.
 
 [[conclicts-conflicts_build]]
 `CONFLICTS_BUILD`::
 If the port cannot be built when other specific ports are already installed. Build conflicts are not recorded in the resulting package.
 
 [[conclicts-conflicts]]
 `CONFLICTS`::
 If the port cannot be built if a certain port is already installed and the resulting package cannot coexist with the other package. `CONFLICTS` check is done prior to the build stage and prior to the install stage.
 
 The most common content of one of these variable is the package base of another port. The package base is the package name without the appended version, it can be obtained by running `make -V PKGBASE`.
 
 [[conflicts-ex1]]
 .Basic usage of `CONFLICTS*`
 [example]
 ====
 
 package:dns/bind99[] cannot be installed if package:dns/bind910[] is present because they install same files. First gather the package base to use:
 
 [source,shell]
 ....
 % make -C dns/bind99 -V PKGBASE
 bind99
 % make -C dns/bind910 -V PKGBASE
 bind910
 ....
 
 Then add to the [.filename]#Makefile# of package:dns/bind99[]:
 
 [.programlisting]
 ....
 CONFLICTS_INSTALL=	bind910
 ....
 
 And add to the [.filename]#Makefile# of package:dns/bind910[]:
 
 [.programlisting]
 ....
 CONFLICTS_INSTALL=	bind99
 ....
 
 ====
 
 Sometimes, only certain versions of another port are incompatible.  When this is the case, use the full package name including the version.  If necessary, use shell globs like `*` and `?` so that all necessary versions are matched.
 
 [[conflicts-ex2]]
 .Using `CONFLICTS*` With Globs.
 [example]
 ====
 
 From versions from 2.0 and up-to 2.4.1_2, package:deskutils/gnotime[] used to install a bundled version of package:databases/qof[].
 
 To reflect this past, the [.filename]#Makefile# of package:databases/qof[] contains:
 
 [.programlisting]
 ....
 CONFLICTS_INSTALL=	gnotime-2.[0-3]* \
 			gnotime-2.4.0* gnotime-2.4.1 \
 			gnotime-2.4.1_[12]
 ....
 
 The first entry match versions `2.0` through `2.3`, the second all the revisions of `2.4.0`, the third the exact `2.4.1` version, and the last the first and second revisions of the `2.4.1` version.
 
 package:deskutils/gnotime[] does not have any conflicts line because its current version does not conflict with anything else.
 ====
 
 The variable `DISABLE_CONFLICTS` may be temporarily set when making targets that are not affected by conflicts.  The variable is not to be set in port Makefiles.
 
 [source,shell]
 ....
 % make -DDISABLE_CONFLICTS patch
 ....
 
 [[install]]
 == Installing Files
 
 [IMPORTANT]
 ====
 The `install` phase is very important to the end user because it adds files to their system. All the additional commands run in the port [.filename]#Makefile#'s `*-install` targets should be echoed to the screen. _Do not_ silence these commands with `@` or `.SILENT`.
 ====
 
 [[install-macros]]
 === `INSTALL_*` Macros
 
 Use the macros provided in [.filename]#bsd.port.mk# to ensure correct modes of files in the port's `*-install` targets. Set ownership directly in [.filename]#pkg-plist# with the corresponding entries, such as `@(_owner_,_group_,)`, `@owner _owner_`, and `@group _group_`. These operators work until overridden, or until the end of [.filename]#pkg-plist#, so remember to reset them after they are no longer needed. The default ownership is `root:wheel`. See crossref:plist[plist-keywords-base,Base Keywords] for more information.
 
 * `INSTALL_PROGRAM` is a command to install binary executables.
 * `INSTALL_SCRIPT` is a command to install executable scripts.
 * `INSTALL_LIB` is a command to install shared libraries (but not static libraries).
 * `INSTALL_KLD` is a command to install kernel loadable modules. Some architectures do not like having the modules stripped, so use this command instead of `INSTALL_PROGRAM`.
 * `INSTALL_DATA` is a command to install sharable data, including static libraries.
 * `INSTALL_MAN` is a command to install manpages and other documentation (it does not compress anything).
 
 These variables are set to the man:install[1] command with the appropriate flags for each situation.
 
 [IMPORTANT]
 ====
 Do not use `INSTALL_LIB` to install static libraries, because stripping them renders them useless. Use `INSTALL_DATA` instead.
 ====
 
 [[install-strip]]
 === Stripping Binaries and Shared Libraries
 
 Installed binaries should be stripped. Do not strip binaries manually unless absolutely required. The `INSTALL_PROGRAM` macro installs and strips a binary at the same time. The `INSTALL_LIB` macro does the same thing to shared libraries.
 
 When a file must be stripped, but neither `INSTALL_PROGRAM` nor `INSTALL_LIB` macros are desirable, `${STRIP_CMD}` strips the program or shared library. This is typically done within the `post-install` target. For example:
 
 [.programlisting]
 ....
 post-install:
 	${STRIP_CMD} ${STAGEDIR}${PREFIX}/bin/xdl
 ....
 
 When multiple files need to be stripped:
 
 [.programlisting]
 ....
 post-install:
 .for l in geometry media body track world
 	${STRIP_CMD} ${STAGEDIR}${PREFIX}/lib/lib${PORTNAME}-${l}.so.0
 .endfor
 ....
 
 Use man:file[1] on a file to determine if it has been stripped. Binaries are reported by man:file[1] as `stripped`, or `not stripped`. Additionally, man:strip[1] will detect programs that have already been stripped and exit cleanly.
 
 [IMPORTANT]
 ====
 When `WITH_DEBUG` is defined, elf files _must not_ be stripped.
 
 The variables (`STRIP_CMD`, `INSTALL_PROGRAM`, `INSTALL_LIB`, ...) and crossref:uses[uses,`USES`] provided by the framework handle this automatically.
 
 Some software, add `-s` to their `LDFLAGS`, in this case, either remove `-s` if `WITH_DEBUG` is set, or remove it unconditionally and use `STRIP_CMD` in `post-install`.
 ====
 
 [[install-copytree]]
 === Installing a Whole Tree of Files
 
 Sometimes, a large number of files must be installed while preserving their hierarchical organization. For example, copying over a whole directory tree from `WRKSRC` to a target directory under `PREFIX`. Note that `PREFIX`, `EXAMPLESDIR`, `DATADIR`, and other path variables must always be prepended with `STAGEDIR` to respect staging (see crossref:special[staging,Staging]).
 
 Two macros exist for this situation. The advantage of using these macros instead of `cp` is that they guarantee proper file ownership and permissions on target files. The first macro, `COPYTREE_BIN`, will set all the installed files to be executable, thus being suitable for installing into [.filename]#PREFIX/bin#. The second macro, `COPYTREE_SHARE`, does not set executable permissions on files, and is therefore suitable for installing files under [.filename]#PREFIX/share# target.
 
 [.programlisting]
 ....
 post-install:
 	${MKDIR} ${STAGEDIR}${EXAMPLESDIR}
 	(cd ${WRKSRC}/examples && ${COPYTREE_SHARE} . ${STAGEDIR}${EXAMPLESDIR})
 ....
 
 This example will install the contents of the [.filename]#examples# directory in the vendor distfile to the proper examples location of the port.
 
 [.programlisting]
 ....
 post-install:
 	${MKDIR} ${STAGEDIR}${DATADIR}/summer
 	(cd ${WRKSRC}/temperatures && ${COPYTREE_SHARE} "June July August" ${STAGEDIR}${DATADIR}/summer)
 ....
 
 And this example will install the data of summer months to the [.filename]#summer# subdirectory of a [.filename]#DATADIR#.
 
 Additional `find` arguments can be passed via the third argument to `COPYTREE_*` macros. For example, to install all files from the first example except Makefiles, one can use these commands.
 
 [.programlisting]
 ....
 post-install:
 	${MKDIR} ${STAGEDIR}${EXAMPLESDIR}
 	(cd ${WRKSRC}/examples && \
 	${COPYTREE_SHARE} . ${STAGEDIR}${EXAMPLESDIR} "! -name Makefile")
 ....
 
 These macros do not add the installed files to [.filename]#pkg-plist#. They must be added manually. For optional documentation (`PORTDOCS`, see <<install-documentation>>) and examples (`PORTEXAMPLES`), the `%%PORTDOCS%%` or `%%PORTEXAMPLES%%` prefixes must be prepended in [.filename]#pkg-plist#.
 
 [[install-documentation]]
 === Install Additional Documentation
 
 If the software has some documentation other than the standard man and info pages that is useful for the user, install it under `DOCSDIR`. This can be done, like the previous item, in the `post-install` target.
 
 Create a new directory for the port. The directory name is `DOCSDIR`. This usually equals `PORTNAME`. However, if the user might want different versions of the port to be installed at the same time, the whole `PKGNAME` can be used.
 
 Since only the files listed in [.filename]#pkg-plist# are installed, it is safe to always install documentation to `STAGEDIR` (see crossref:special[staging,Staging]). Hence `.if` blocks are only needed when the installed files are large enough to cause significant I/O overhead.
 
 [.programlisting]
 ....
 post-install:
 	${MKDIR} ${STAGEDIR}${DOCSDIR}
 	${INSTALL_MAN} ${WRKSRC}/docs/xvdocs.ps ${STAGEDIR}${DOCSDIR}
 ....
 
 On the other hand, if there is a DOCS option in the port, install the documentation in a `post-install-DOCS-on` target. These targets are described in <<options-targets>>.
 
 Here are some handy variables and how they are expanded by default when used in the [.filename]#Makefile#:
 
 * `DATADIR` gets expanded to [.filename]#PREFIX/shared/PORTNAME#.
 * `DATADIR_REL` gets expanded to [.filename]#share/PORTNAME#.
 * `DOCSDIR` gets expanded to [.filename]#PREFIX/shared/doc/PORTNAME#.
 * `DOCSDIR_REL` gets expanded to [.filename]#share/doc/PORTNAME#.
 * `EXAMPLESDIR` gets expanded to [.filename]#PREFIX/shared/examples/PORTNAME#.
 * `EXAMPLESDIR_REL` gets expanded to [.filename]#share/examples/PORTNAME#.
 
 [NOTE]
 ====
 The `DOCS` option only controls additional documentation installed in `DOCSDIR`. It does not apply to standard man pages and info pages. Things installed in `EXAMPLESDIR` are controlled by the `EXAMPLES` option.
 ====
 
 These variables are exported to `PLIST_SUB`. Their values will appear there as pathnames relative to [.filename]#PREFIX# if possible. That is, [.filename]#share/doc/PORTNAME# will be substituted for `%%DOCSDIR%%` in the packing list by default, and so on. (See more on [.filename]#pkg-plist# substitution crossref:plist[plist-sub,here].)
 
 All conditionally installed documentation files and directories are included in [.filename]#pkg-plist# with the `%%PORTDOCS%%` prefix, for example:
 
 [.programlisting]
 ....
 %%PORTDOCS%%%%DOCSDIR%%/AUTHORS
 %%PORTDOCS%%%%DOCSDIR%%/CONTACT
 ....
 
 As an alternative to enumerating the documentation files in [.filename]#pkg-plist#, a port can set the variable `PORTDOCS` to a list of file names and shell glob patterns to add to the final packing list. The names will be relative to `DOCSDIR`. Therefore, a port that utilizes `PORTDOCS`, and uses a non-default location for its documentation, must set `DOCSDIR` accordingly. If a directory is listed in `PORTDOCS` or matched by a glob pattern from this variable, the entire subtree of contained files and directories will be registered in the final packing list. If the `DOCS` option has been unset then files and directories listed in `PORTDOCS` would not be installed or added to port packing list. Installing the documentation at `PORTDOCS` as shown above remains up to the port itself. A typical example of utilizing `PORTDOCS`:
 
 [.programlisting]
 ....
 PORTDOCS=	README.* ChangeLog docs/*
 ....
 
 [NOTE]
 ====
 The equivalents of `PORTDOCS` for files installed under `DATADIR` and `EXAMPLESDIR` are `PORTDATA` and `PORTEXAMPLES`, respectively.
 
 The contents of [.filename]#pkg-message# are displayed upon installation. See crossref:pkg-files[porting-message,the section on using [.filename]#pkg-message#] for details. [.filename]#pkg-message# does not need to be added to [.filename]#pkg-plist#.
 ====
 
 [[install-subdirs]]
 === Subdirectories Under `PREFIX`
 
 Try to let the port put things in the right subdirectories of `PREFIX`. Some ports lump everything and put it in the subdirectory with the port's name, which is incorrect. Also, many ports put everything except binaries, header files and manual pages in a subdirectory of [.filename]#lib#, which does not work well with the BSD paradigm. Many of the files must be moved to one of these directories: [.filename]#etc# (setup/configuration files), [.filename]#libexec# (executables started internally), [.filename]#sbin# (executables for superusers/managers), [.filename]#info# (documentation for info browser) or [.filename]#share# (architecture independent files). See man:hier[7] for details; the rules governing [.filename]#/usr# pretty much apply to [.filename]#/usr/local# too. The exception are ports dealing with USENET "news". They may use [.filename]#PREFIX/news# as a destination for their files.
 
 [[binary-alias]]
 == Use `BINARY_ALIAS` to Rename Commands Instead of Patching the Build
 
 When `BINARY_ALIAS` is defined it will create symlinks of the given commands in a directory which will be prepended to `PATH`.
 
 Use it to substitute hardcoded commands the build phase relies on without having to patch any build files.
 
 [[binary-alias-ex1]]
 .Using `BINARY_ALIAS` to Make `gsed` Available as `sed`
 [example]
 ====
 
 Some ports expect `sed` to behave like GNU sed and use features that man:sed[1] does not provide. GNU sed is available from package:textproc/gsed[] on FreeBSD.
 
 Use `BINARY_ALIAS` to substitute `sed` with `gsed` for the duration of the build:
 
 [.programlisting]
 ....
 BUILD_DEPENDS=	gsed:textproc/gsed
 ...
 BINARY_ALIAS=	sed=gsed
 ....
 
 ====
 
 [[binary-alias-ex2]]
 .Using `BINARY_ALIAS` to Provide Aliases for Hardcoded `python3` Commands
 [example]
 ====
 
 A port that has a hardcoded reference to `python3` in its build scripts will need to have it available in `PATH` at build time. Use `BINARY_ALIAS` to create an alias that points to the right Python 3 binary:
 
 [.programlisting]
 ....
 USES=	python:3.4+,build
 ...
 BINARY_ALIAS=	python3=${PYTHON_CMD}
 ....
 
 See crossref:special[using-python,Using Python] for more information about `USES=python`.
 ====
 
 [NOTE]
 ====
 Binary aliases are created after the dependencies provided via `BUILD_DEPENDS` and `LIB_DEPENDS` are processed and before the `configure` target. This leads to various limitations. For example, programs installed via `TEST_DEPENDS` cannot be used to create a binary alias as test dependencies specified this way are processed after binary aliases are created.
 ====
diff --git a/documentation/content/en/books/porters-handbook/porting-dads/_index.adoc b/documentation/content/en/books/porters-handbook/porting-dads/_index.adoc
index 8339653fc1..a4cb6add7b 100644
--- a/documentation/content/en/books/porters-handbook/porting-dads/_index.adoc
+++ b/documentation/content/en/books/porters-handbook/porting-dads/_index.adoc
@@ -1,467 +1,467 @@
 ---
 title: Chapter 13. Dos and Don'ts
 prev: books/porters-handbook/security
 next: books/porters-handbook/porting-samplem
 description: A list of common dos and don'ts that are encountered during the FreeBSD porting process
 tags: ["dos", "don'ts", "porting", "ports", "guide"]
 ---
 
 [[porting-dads]]
 = Dos and Don'ts
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 13
 :freebsd-version: __FreeBSD_version
 :freebsd: __FreeBSD__
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 [[dads-intro]]
 == Introduction
 
 Here is a list of common dos and don'ts that are encountered during the porting process. Check the port against this list, but also check ports in the https://bugs.FreeBSD.org/search/[PR database] that others have submitted. Submit any comments on ports as described in link:{contributing}#CONTRIB-GENERAL[Bug Reports and General Commentary]. Checking ports in the PR database will both make it faster for us to commit them, and prove that you know what you are doing.
 
 [[porting-wrkdir]]
 == `WRKDIR`
 
 Do not write anything to files outside `WRKDIR`. `WRKDIR` is the only place that is guaranteed to be writable during the port build (see link:{handbook}#PORTS-CD[ installing ports from a CDROM] for an example of building ports from a read-only tree). The [.filename]##pkg-*## files can be modified by crossref:pkg-files[pkg-names,redefining a variable] rather than overwriting the file.
 
 [[porting-wrkdirprefix]]
 == `WRKDIRPREFIX`
 
 Make sure the port honors `WRKDIRPREFIX`.
 Most ports do not have to worry about this.
 In particular, when referring to a `WRKDIR` of another port, note that the correct location is [.filename]#${WRKDIRPREFIX}${PORTSDIR}/subdir/name/work# not [.filename]#${PORTSDIR}/subdir/name/work# or [.filename]#${.CURDIR}/../../subdir/name/work# or some such.
 
 [[porting-versions]]
 == Differentiating Operating Systems and OS Versions
 
 Some code needs modifications or conditional compilation based upon what version of FreeBSD Unix it is running under. The preferred way to tell FreeBSD versions apart are the `{freebsd-version}` and `{freebsd}` macros defined in https://cgit.freebsd.org/src/tree/sys/sys/param.h[sys/param.h]. If this file is not included add the code,
 
 [.programlisting]
 ....
 #include <sys/param.h>
 ....
 
 to the proper place in the [.filename]#.c# file.
 
 `{freebsd}` is defined in all versions of FreeBSD as their major version number. For example, in FreeBSD 9.x, `{freebsd}` is defined to be `9`.
 
 [.programlisting]
 ....
 #if __FreeBSD__ >= 9
 #  if __FreeBSD_version >= 901000
 	 /* 9.1+ release specific code here */
 #  endif
 #endif
 ....
 
 A complete list of `{freebsd-version}` values is available in crossref:versions[versions,__FreeBSD_version Values].
 
 [[dads-after-port-mk]]
 == Writing Something After bsd.port.mk
 
 Do not write anything after the `.include <bsd.port.mk>` line. It usually can be avoided by including [.filename]#bsd.port.pre.mk# somewhere in the middle of the [.filename]#Makefile# and [.filename]#bsd.port.post.mk# at the end.
 
 [IMPORTANT]
 ====
 Include either the [.filename]#bsd.port.pre.mk#/[.filename]#bsd.port.post.mk# pair or [.filename]#bsd.port.mk# only; do not mix these two usages.
 ====
 
 [.filename]#bsd.port.pre.mk# only defines a few variables, which can be used in tests in the [.filename]#Makefile#, [.filename]#bsd.port.post.mk# defines the rest.
 
 Here are some important variables defined in [.filename]#bsd.port.pre.mk# (this is not the complete list, please read [.filename]#bsd.port.mk# for the complete list).
 
 [.informaltable]
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 
 |`ARCH`
 |The architecture as returned by `uname -m` (for example, `i386`)
 
 |`OPSYS`
 |The operating system type, as returned by `uname -s` (for example, `FreeBSD`)
 
 |`OSREL`
 |The release version of the operating system (for example, `2.1.5` or `2.2.7`)
 
 |`OSVERSION`
 |The numeric version of the operating system; the same as crossref:versions[versions,`{freebsd-version}`].
 
 |`LOCALBASE`
 |The base of the "local" tree (for example, `/usr/local`)
 
 |`PREFIX`
 |Where the port installs itself (see crossref:testing[porting-prefix,more on `PREFIX`]).
 |===
 
 [NOTE]
 ====
 When `MASTERDIR` is needed, always define it before including [.filename]#bsd.port.pre.mk#.
 ====
 
 Here are some examples of things that can be added after [.filename]#bsd.port.pre.mk#:
 
 [.programlisting]
 ....
 # no need to compile lang/perl5 if perl5 is already in system
 .if ${OSVERSION} > 300003
 BROKEN=	perl is in system
 .endif
 ....
 
 Always use tab instead of spaces after `BROKEN=`.
 
 [[dads-sh-exec]]
 == Use the `exec` Statement in Wrapper Scripts
 
 If the port installs a shell script whose purpose is to launch another program, and if launching that program is the last action performed by the script, make sure to launch the program using the `exec` statement, for instance:
 
 [.programlisting]
 ....
 #!/bin/sh
 exec %%LOCALBASE%%/bin/java -jar %%DATADIR%%/foo.jar "$@"
 ....
 
 The `exec` statement replaces the shell process with the specified program. If `exec` is omitted, the shell process remains in memory while the program is executing, and needlessly consumes system resources.
 
 [[dads-rational]]
 == Do Things Rationally
 
 The [.filename]#Makefile# should do things in a simple and reasonable manner. Making it a couple of lines shorter or more readable is always better. Examples include using a make `.if` construct instead of a shell `if` construct, not redefining `do-extract` if redefining `EXTRACT*` is enough, and using `GNU_CONFIGURE` instead of `CONFIGURE_ARGS += --prefix=${PREFIX}`.
 
 If a lot of new code is needed to do something, there may already be an implementation of it in [.filename]#bsd.port.mk#. While hard to read, there are a great many seemingly-hard problems for which [.filename]#bsd.port.mk# already provides a shorthand solution.
 
 [[dads-cc]]
 == Respect Both `CC` and `CXX`
 
 The port must respect both `CC` and `CXX`. What we mean by this is that the port must not set the values of these variables absolutely, overriding existing values; instead, it may append whatever values it needs to the existing values. This is so that build options that affect all ports can be set globally.
 
 If the port does not respect these variables, please add `NO_PACKAGE=ignores either cc or cxx` to the [.filename]#Makefile#.
 
 Here is an example of a [.filename]#Makefile# respecting both `CC` and `CXX`. Note the `?=`:
 
 [.programlisting]
 ....
 CC?= gcc
 ....
 
 [.programlisting]
 ....
 CXX?= g++
 ....
 
 Here is an example which respects neither `CC` nor `CXX`:
 
 [.programlisting]
 ....
 CC= gcc
 ....
 
 [.programlisting]
 ....
 CXX= g++
 ....
 
 Both `CC` and `CXX` can be defined on FreeBSD systems in [.filename]#/etc/make.conf#. The first example defines a value if it was not previously set in [.filename]#/etc/make.conf#, preserving any system-wide definitions. The second example clobbers anything previously defined.
 
 [[dads-cflags]]
 == Respect `CFLAGS`
 
 The port must respect `CFLAGS`. What we mean by this is that the port must not set the value of this variable absolutely, overriding the existing value. Instead, it may append whatever values it needs to the existing value. This is so that build options that affect all ports can be set globally.
 
 If it does not, please add `NO_PACKAGE=ignores cflags` to the [.filename]#Makefile#.
 
 Here is an example of a [.filename]#Makefile# respecting `CFLAGS`. Note the `+=`:
 
 [.programlisting]
 ....
 CFLAGS+= -Wall -Werror
 ....
 
 Here is an example which does not respect `CFLAGS`:
 
 [.programlisting]
 ....
 CFLAGS= -Wall -Werror
 ....
 
 `CFLAGS` is defined on FreeBSD systems in [.filename]#/etc/make.conf#. The first example appends additional flags to `CFLAGS`, preserving any system-wide definitions. The second example clobbers anything previously defined.
 
 Remove optimization flags from the third party [.filename]##Makefile##s. The system `CFLAGS` contains system-wide optimization flags. An example from an unmodified [.filename]#Makefile#:
 
 [.programlisting]
 ....
 CFLAGS= -O3 -funroll-loops -DHAVE_SOUND
 ....
 
 Using system optimization flags, the [.filename]#Makefile# would look similar to this example:
 
 [.programlisting]
 ....
 CFLAGS+= -DHAVE_SOUND
 ....
 
 [[dads-verbose-logs]]
 == Verbose Build Logs
 
 Make the port build system display all commands executed during the build stage. Complete build logs are crucial to debugging port problems.
 
 Non-informative build log example (bad):
 
 [.programlisting]
 ....
   CC     source1.o
   CC     source2.o
   CCLD   someprogram
 ....
 
 Verbose build log example (good):
 
 [.programlisting]
 ....
 cc -O2 -pipe -I/usr/local/include -c -o source1.o source1.c
 cc -O2 -pipe -I/usr/local/include -c -o source2.o source2.c
 cc -o someprogram source1.o source2.o -L/usr/local/lib -lsomelib
 ....
 
 Some build systems such as CMake, ninja, and GNU configure are set up for verbose logging by the ports framework. In other cases, ports might need individual tweaks.
 
 [[dads-feedback]]
 == Feedback
 
 Do send applicable changes and patches to the upstream maintainer for inclusion in the next release of the code. This makes updating to the next release that much easier.
 
 [[dads-readme]]
 == README.html
 
 [.filename]#README.html# is not part of the port, but generated by `make readme`. Do not include this file in patches or commits.
 
 [NOTE]
 ====
 If `make readme` fails, make sure that the default value of `ECHO_MSG` has not been modified by the port.
 ====
 
 [[dads-noinstall]]
 == Marking a Port Not Installable with `BROKEN`, `FORBIDDEN`, or `IGNORE`
 
 In certain cases, users must be prevented from installing a port. There are several variables that can be used in a port's [.filename]#Makefile# to tell the user that the port cannot be installed. The value of these make variables will be the reason that is shown to users for why the port refuses to install itself. Please use the correct make variable. Each variable conveys radically different meanings, both to users and to automated systems that depend on [.filename]##Makefile##s, such as crossref:keeping-up[build-cluster,the ports build cluster], crossref:keeping-up[freshports,FreshPorts], and crossref:keeping-up[portsmon,portsmon].
 
 [[dads-noinstall-variables]]
 === Variables
 
 * `BROKEN` is reserved for ports that currently do not compile, install, deinstall, or run correctly. Use it for ports where the problem is believed to be temporary.
-+ 
++
 If instructed, the build cluster will still attempt to try to build them to see if the underlying problem has been resolved. (However, in general, the cluster is run without this.)
-+ 
++
 For instance, use `BROKEN` when a port:
 
 ** does not compile
 ** fails its configuration or installation process
 ** installs files outside of [.filename]#${PREFIX}#
 ** does not remove all its files cleanly upon deinstall (however, it may be acceptable, and desirable, for the port to leave user-modified files behind)
 ** has runtime issues on systems where it is supposed to run fine.
 
 * `FORBIDDEN` is used for ports that contain a security vulnerability or induce grave concern regarding the security of a FreeBSD system with a given port installed (for example, a reputably insecure program or a program that provides easily exploitable services). Mark ports as `FORBIDDEN` as soon as a particular piece of software has a vulnerability and there is no released upgrade. Ideally upgrade ports as soon as possible when a security vulnerability is discovered so as to reduce the number of vulnerable FreeBSD hosts (we like being known for being secure), however sometimes there is a noticeable time gap between disclosure of a vulnerability and an updated release of the vulnerable software. Do not mark a port `FORBIDDEN` for any reason other than security.
 * `IGNORE` is reserved for ports that must not be built for some other reason. Use it for ports where the problem is believed to be structural. The build cluster will not, under any circumstances, build ports marked as `IGNORE`. For instance, use `IGNORE` when a port:
 
 ** does not work on the installed version of FreeBSD
 ** has a distfile which may not be automatically fetched due to licensing restrictions
 ** does not work with some other currently installed port (for instance, the port depends on package:www/apache20[] but package:www/apache22[] is installed)
 +
 [NOTE]
 ====
 If a port would conflict with a currently installed port (for example, if they install a file in the same place that performs a different function), crossref:makefiles[conflicts,use `CONFLICTS` instead]. `CONFLICTS` will set `IGNORE` by itself.
 ====
 
 [[dads-noinstall-notes]]
 === Implementation Notes
 
 Do not quote the values of `BROKEN`, `IGNORE`, and related variables. Due to the way the information is shown to the user, the wording of messages for each variable differ:
 
 [.programlisting]
 ....
 BROKEN=	fails to link with base -lcrypto
 ....
 
 [.programlisting]
 ....
 IGNORE=	unsupported on recent versions
 ....
 
 resulting in this output from `make describe`:
 
 [.programlisting]
 ....
 ===>  foobar-0.1 is marked as broken: fails to link with base -lcrypto.
 ....
 
 [.programlisting]
 ....
 ===>  foobar-0.1 is unsupported on recent versions.
 ....
 
 [[dads-arch]]
 == Architectural Considerations
 
 [[dads-arch-general]]
 === General Notes on Architectures
 
 FreeBSD runs on many more processor architectures than just the well-known x86-based ones. Some ports have constraints which are particular to one or more of these architectures.
 
 For the list of supported architectures, run:
 
 [.programlisting]
 ....
 cd ${SRCDIR}; make targets
 ....
 
 The values are shown in the form `TARGET`/`TARGET_ARCH`. The ports read-only makevar `ARCH` is set based on the value of `TARGET_ARCH`. Port [.filename]##Makefile##s should test the value of this Makevar.
 
 [[dads-arch-neutral]]
 === Marking a Port as Architecture Neutral
 
 Ports that do not have any architecture-dependent files or requirements are identified by setting `NO_ARCH=yes`.
 
 [NOTE]
 ====
 `NO_ARCH` is meant to indicate that there is no need to build a package for each of the supported architectures. The goal is to reduce the amount of resources spent on building and distributing the packages such as network bandwidth and disk space on mirrors and on distribution media. Currently, however, our package infrastructure (e.g., package managers, mirrors, and package builders) is not set up to fully benefit from `NO_ARCH`.
 ====
 
 [[dads-arch-ignore]]
 === Marking a Port as Ignored Only On Certain Architectures
 
 * To mark a port as ``IGNORE``d only on certain architectures, there are two other convenience variables that will automatically set `IGNORE`: `ONLY_FOR_ARCHS` and `NOT_FOR_ARCHS`. Examples:
 +
 [.programlisting]
 ....
 ONLY_FOR_ARCHS=	i386 amd64
 ....
 +
 [.programlisting]
 ....
 NOT_FOR_ARCHS=	ia64 sparc64
 ....
-+ 
++
 A custom `IGNORE` message can be set using `ONLY_FOR_ARCHS_REASON` and `NOT_FOR_ARCHS_REASON`. Per architecture entries are possible with `ONLY_FOR_ARCHS_REASON_ARCH` and `NOT_FOR_ARCHS_REASON_ARCH`.
 
 [[dads-arch-i386]]
 * If a port fetches i386 binaries and installs them, set `IA32_BINARY_PORT`. If this variable is set, [.filename]#/usr/lib32# must be present for IA32 versions of libraries and the kernel must support IA32 compatibility. If one of these two dependencies is not satisfied, `IGNORE` will be set automatically.
 
 [[dads-arch-cluster]]
 === Cluster-Specific Considerations
 
 * Some ports attempt to tune themselves to the exact machine they are being built on by specifying `-march=native` to the compiler. This should be avoided: either list it under an off-by-default option, or delete it entirely.
-+ 
++
 Otherwise, the default package produced by the build cluster might not run on every single machine of that `ARCH`.
 
 [[dads-deprecated]]
 == Marking a Port for Removal with `DEPRECATED` or `EXPIRATION_DATE`
 
 Do remember that `BROKEN` and `FORBIDDEN` are to be used as a temporary resort if a port is not working. Permanently broken ports will be removed from the tree entirely.
 
 When it makes sense to do so, users can be warned about a pending port removal with `DEPRECATED` and `EXPIRATION_DATE`. The former is a string stating why the port is scheduled for removal; the latter is a string in ISO 8601 format (YYYY-MM-DD). Both will be shown to the user.
 
 It is possible to set `DEPRECATED` without an `EXPIRATION_DATE` (for instance, recommending a newer version of the port), but the converse does not make any sense.
 
 There is no set policy on how much notice to give. Current practice seems to be one month for security-related issues and two months for build issues. This also gives any interested committers a little time to fix the problems.
 
 [[dads-dot-error]]
 == Avoid Use of the `.error` Construct
 
 The correct way for a [.filename]#Makefile# to signal that the port cannot be installed due to some external factor (for instance, the user has specified an illegal combination of build options) is to set a non-blank value to `IGNORE`. This value will be formatted and shown to the user by `make install`.
 
 It is a common mistake to use `.error` for this purpose. The problem with this is that many automated tools that work with the ports tree will fail in this situation. The most common occurrence of this is seen when trying to build [.filename]#/usr/ports/INDEX# (see crossref:testing[make-describe,Running `make describe`]). However, even more trivial commands such as `make maintainer` also fail in this scenario. This is not acceptable.
 
 [[dot-error-breaks-index]]
 .How to Avoid Using `.error`
 [example]
 ====
 
 The first of the next two [.filename]#Makefile# snippets will cause `make index` to fail, while the second one will not:
 
 [.programlisting]
 ....
 .error "option is not supported"
 ....
 
 [.programlisting]
 ....
 IGNORE=option is not supported
 ....
 
 ====
 
 [[dads-sysctl]]
 == Usage of sysctl
 
 The usage of [.filename]#sysctl# is discouraged except in targets. This is because the evaluation of any ``makevar``s, such as used during `make index`, then has to run the command, further slowing down that process.
 
 Only use man:sysctl[8] through `SYSCTL`, as it contains the fully qualified path and can be overridden, if one has such a special need.
 
 [[dads-rerolling-distfiles]]
 == Rerolling Distfiles
 
 Sometimes the authors of software change the content of released distfiles without changing the file's name. Verify that the changes are official and have been performed by the author. It has happened in the past that the distfile was silently altered on the download servers with the intent to cause harm or compromise end user security.
 
 Put the old distfile aside, download the new one, unpack them and compare the content with man:diff[1]. If there is nothing suspicious, update [.filename]#distinfo#.
 
 [IMPORTANT]
 ====
 Be sure to summarize the differences in the PR and commit log, so that other people know that nothing bad has happened.
 ====
 
 Contact the authors of the software and confirm the changes with them.
 
 [[dads-use-posix-standards]]
 == Use POSIX Standards
 
 FreeBSD ports generally expect POSIX compliance. Some software and build systems make assumptions based on a particular operating system or environment that can cause problems when used in a port.
 
 Do not use [.filename]#/proc# if there are any other ways of getting the information. For example, `setprogname(argv[0])` in `main()` and then man:getprogname[3] to know the executable name.
 
 Do not rely on behavior that is undocumented by POSIX.
 
 Do not record timestamps in the critical path of the application if it also works without. Getting timestamps may be slow, depending on the accuracy of timestamps in the OS. If timestamps are really needed, determine how precise they have to be and use an API which is documented to just deliver the needed precision.
 
 A number of simple syscalls (for example man:gettimeofday[2], man:getpid[2]) are much faster on Linux(R) than on any other operating system due to caching and the vsyscall performance optimizations. Do not rely on them being cheap in performance-critical applications. In general, try hard to avoid syscalls if possible.
 
 Do not rely on Linux(R)-specific socket behavior. In particular, default socket buffer sizes are different (call man:setsockopt[2] with `SO_SNDBUF` and `SO_RCVBUF`, and while Linux(R)'s man:send[2] blocks when the socket buffer is full, FreeBSD's will fail and set `ENOBUFS` in errno.
 
 If relying on non-standard behavior is required, encapsulate it properly into a generic API, do a check for the behavior in the configure stage, and stop if it is missing.
 
 Check the https://www.freebsd.org/cgi/man.cgi[man pages] to see if the function used is a POSIX interface (in the "STANDARDS" section of the man page).
 
 Do not assume that [.filename]#/bin/sh# is bash. Ensure that a command line passed to man:system[3] will work with a POSIX compliant shell.
 
 A list of common bashisms is available https://wiki.ubuntu.com/DashAsBinSh[here].
 
 Check that headers are included in the POSIX or man page recommended way. For example, [.filename]#sys/types.h# is often forgotten, which is not as much of a problem for Linux(R) as it is for FreeBSD.
 
 [[dads-misc]]
 == Miscellanea
 
 Always double-check [.filename]#pkg-descr# and [.filename]#pkg-plist#. If reviewing a port and a better wording can be achieved, do so.
 
 Do not copy more copies of the GNU General Public License into our system, please.
 
 Please be careful to note any legal issues! Do not let us illegally distribute software!
diff --git a/documentation/content/en/books/porters-handbook/special/_index.adoc b/documentation/content/en/books/porters-handbook/special/_index.adoc
index 64748f5290..4035885da7 100644
--- a/documentation/content/en/books/porters-handbook/special/_index.adoc
+++ b/documentation/content/en/books/porters-handbook/special/_index.adoc
@@ -1,4329 +1,4329 @@
 ---
 title: Chapter 6. Special Considerations
 prev: books/porters-handbook/makefiles
 next: books/porters-handbook/flavors
 description: Special considerations when creating a new FreeBSD Port
 tags: ["special considerations", "Handling Symbolic Links", "Bundled Libraries"]
 ---
 
 [[special]]
 = Special Considerations
 :doctype: book
 :toc: macro
 :toclevels: 1
 :icons: font
 :sectnums:
 :sectnumlevels: 6
 :source-highlighter: rouge
 :experimental:
 :skip-front-matter:
 :xrefstyle: basic
 :relfileprefix: ../
 :outfilesuffix:
 :sectnumoffset: 6
 
 include::shared/mirrors.adoc[]
 include::shared/authors.adoc[]
 include::shared/releases.adoc[]
 include::shared/en/mailing-lists.adoc[]
 include::shared/en/teams.adoc[]
 include::shared/en/urls.adoc[]
 
 toc::[]
 
 This section explains the most common things to consider when creating a port.
 
 [[staging]]
 == Staging
 
 [.filename]#bsd.port.mk# expects ports to work with a "stage directory". This means that a port must not install files directly to the regular destination directories (that is, under `PREFIX`, for example) but instead into a separate directory from which the package is then built. In many cases, this does not require root privileges, making it possible to build packages as an unprivileged user. With staging, the port is built and installed into the stage directory, `STAGEDIR`. A package is created from the stage directory and then installed on the system. Automake tools refer to this concept as `DESTDIR`, but in FreeBSD, `DESTDIR` has a different meaning (see crossref:testing[porting-prefix,`PREFIX` and `DESTDIR`]).
 
 [NOTE]
 ====
 No port _really_ needs to be root. It can mostly be avoided by using crossref:uses[uses-uidfix,`USES=uidfix`]. If the port still runs commands like man:chown[8], man:chgrp[1], or forces owner or group with man:install[1] then use crossref:uses[uses-fakeroot,`USES=fakeroot`] to fake those calls. Some patching of the port's [.filename]#Makefiles# will be needed.
 ====
 
 Meta ports, or ports that do not install files themselves but only depend on other ports, must avoid needlessly extracting the man:mtree[8] to the stage directory. This is the basic directory layout of the package, and these empty directories will be seen as orphans. To prevent man:mtree[8] extraction, add this line:
 
 [.programlisting]
 ....
 NO_MTREE=	yes
 ....
 
 [TIP]
 ====
 Metaports should use <<uses-metaport,`USES=metaport`>>. It sets up defaults for ports that do not fetch, build, or install anything.
 ====
 
 Staging is enabled by prepending `STAGEDIR` to paths used in the `pre-install`, `do-install`, and `post-install` targets (see the examples through the book). Typically, this includes `PREFIX`, `ETCDIR`, `DATADIR`, `EXAMPLESDIR`, `MANPREFIX`, `DOCSDIR`, and so on. Directories should be created as part of the `post-install` target. Avoid using absolute paths whenever possible.
 
 [TIP]
 ====
 Ports that install kernel modules must prepend `STAGEDIR` to their destination, by default [.filename]#/boot/modules#.
 ====
 
 [[staging-symlink]]
 === Handling Symbolic Links
 
 When creating a symbolic link, relative ones are strongly recommended. Use `${RLN}` to create relative symbolic links. It uses man:install[1] under the hood to automatically figure out the relative link to create.
 
 [[staging-ex1]]
 .Create Relative Symbolic Links Automatically
 [example]
 ====
 `${RLN}` uses man:install[1]'s relative symbolic feature which frees the porter of computing the relative path.
 
 [.programlisting]
 ....
 ${RLN} ${STAGEDIR}${PREFIX}/lib/libfoo.so.42 ${STAGEDIR}${PREFIX}/lib/libfoo.so
 ${RLN} ${STAGEDIR}${PREFIX}/libexec/foo/bar ${STAGEDIR}${PREFIX}/bin/bar
 ${RLN} ${STAGEDIR}/var/cache/foo ${STAGEDIR}${PREFIX}/share/foo
 ....
 
 Will generate:
 
 [source,shell]
 ....
 % ls -lF ${STAGEDIR}${PREFIX}/lib
 lrwxr-xr-x  1 nobody  nobody    181 Aug  3 11:27 libfoo.so@ -> libfoo.so.42
 -rwxr-xr-x  1 nobody  nobody     15 Aug  3 11:24 libfoo.so.42*
 % ls -lF ${STAGEDIR}${PREFIX}/bin
 lrwxr-xr-x  1 nobody  nobody    181 Aug  3 11:27 bar@ -> ../libexec/foo/bar
 % ls -lF ${STAGEDIRDIR}${PREFIX}/share
 lrwxr-xr-x  1 nobody  nobody    181 Aug  3 11:27 foo@ -> ../../../var/cache/foo
 ....
 
 ====
 
 [[bundled-libs]]
 == Bundled Libraries
 
 This section explains why bundled dependencies are considered bad and what to do about them.
 
 [[bundled-libs-why-bad]]
 === Why Bundled Libraries Are Bad
 
 Some software requires the porter to locate third-party libraries and add the required dependencies to the port. Other software bundles all necessary libraries into the distribution file. The second approach seems easier at first, but there are some serious drawbacks:
 
 This list is loosely based on the https://fedoraproject.org/wiki/Packaging:No_Bundled_Libraries[Fedora] and http://wiki.gentoo.org/wiki/Why_not_bundle_dependencies[Gentoo] wikis, both licensed under the http://creativecommons.org/licenses/by-sa/3.0/[CC-BY-SA 3.0] license.
 
 Security::
 If vulnerabilities are found in the upstream library and fixed there, they might not be fixed in the library bundled with the port. One reason could be that the author is not aware of the problem. This means that the porter must fix them, or upgrade to a non-vulnerable version, and send a patch to the author. This all takes time, which results in software being vulnerable longer than necessary. This in turn makes it harder to coordinate a fix without unnecessarily leaking information about the vulnerability.
 
 Bugs::
 This problem is similar to the problem with security in the last paragraph, but generally less severe.
 
 Forking::
 It is easier for the author to fork the upstream library once it is bundled. While convenient on first sight, it means that the code diverges from upstream making it harder to address security or other problems with the software. A reason for this is that patching becomes harder.
 +
 Another problem of forking is that because code diverges from upstream, bugs get solved over and over again instead of just once at a central location. This defeats the idea of open source software in the first place.
 
 Symbol collision::
 When a library is installed on the system, it might collide with the bundled version. This can cause immediate errors at compile or link time. It can also cause errors when running the program which might be harder to track down. The latter problem could be caused because the versions of the two libraries are incompatible.
 
 Licensing::
 When bundling projects from different sources, license issues can arise more easily, especially when licenses are incompatible.
 
 Waste of resources::
 Bundled libraries waste resources on several levels. It takes longer to build the actual application, especially if these libraries are already present on the system. At run-time, they can take up unnecessary memory when the system-wide library is already loaded by one program and the bundled library is loaded by another program.
 
 Waste of effort::
 When a library needs patches for FreeBSD, these patches have to be duplicated again in the bundled library. This wastes developer time because the patches might not apply cleanly. It can also be hard to notice that these patches are required in the first place.
 
 [[bundled-libs-practices]]
 === What to do About Bundled Libraries
 
 Whenever possible, use the unbundled version of the library by adding a `LIB_DEPENDS` to the port. If such a port does not exist yet, consider creating it.
 
 Only use bundled libraries if the upstream has a good track record on security and using unbundled versions leads to overly complex patches.
 
 [NOTE]
 ====
 In some very special cases, for example emulators, like Wine, a port has to bundle libraries, because they are in a different architecture, or they have been modified to fit the software's use. In that case, those libraries should not be exposed to other ports for linking. Add `BUNDLE_LIBS=yes` to the port's [.filename]#Makefile#. This will tell man:pkg[8] to not compute provided libraries. Always ask the {portmgr} before adding this to a port.
 ====
 
 [[porting-shlibs]]
 == Shared Libraries
 
 If the port installs one or more shared libraries, define a `USE_LDCONFIG` make variable, which will instruct a [.filename]#bsd.port.mk# to run `${LDCONFIG} -m` on the directory where the new library is installed (usually [.filename]#PREFIX/lib#) during `post-install` target to register it into the shared library cache. This variable, when defined, will also facilitate addition of an appropriate `@exec /sbin/ldconfig -m` and `@unexec /sbin/ldconfig -R` pair into [.filename]#pkg-plist#, so that a user who installed the package can start using the shared library immediately and de-installation will not cause the system to still believe the library is there.
 
 [.programlisting]
 ....
 USE_LDCONFIG=	yes
 ....
 
 The default directory can be overridden by setting `USE_LDCONFIG` to a list of directories into which shared libraries are to be installed. For example, if the port installs shared libraries into [.filename]#PREFIX/lib/foo# and [.filename]#PREFIX/lib/bar# use this in [.filename]#Makefile#:
 
 [.programlisting]
 ....
 USE_LDCONFIG=	${PREFIX}/lib/foo ${PREFIX}/lib/bar
 ....
 
 Please double-check, often this is not necessary at all or can be avoided through `-rpath` or setting `LD_RUN_PATH` during linking (see package:lang/mosml[] for an example), or through a shell-wrapper which sets `LD_LIBRARY_PATH` before invoking the binary, like package:www/seamonkey[] does.
 
 When installing 32-bit libraries on a 64-bit system, use `USE_LDCONFIG32` instead.
 
 If the software uses <<using-autotools,autotools>>, and specifically `libtool`, add crossref:uses[uses-libtool,`USES=libtool`].
 
 When the major library version number increments in the update to the new port version, all other ports that link to the affected library must have their `PORTREVISION` incremented, to force recompilation with the new library version.
 
 [[porting-restrictions]]
 == Ports with Distribution Restrictions or Legal Concerns
 
 Licenses vary, and some of them place restrictions on how the application can be packaged, whether it can be sold for profit, and so on.
 
 [IMPORTANT]
 ====
 It is the responsibility of a porter to read the licensing terms of the software and make sure that the FreeBSD project will not be held accountable for violating them by redistributing the source or compiled binaries either via FTP/HTTP or CD-ROM. If in doubt, please contact the {freebsd-ports}.
 ====
 
 In situations like this, the variables described in the next sections can be set.
 
 [[porting-restrictions-no_package]]
 === `NO_PACKAGE`
 
 This variable indicates that we may not generate a binary package of the application. For instance, the license may disallow binary redistribution, or it may prohibit distribution of packages created from patched sources.
 
 However, the port's `DISTFILES` may be freely mirrored on FTP/HTTP. They may also be distributed on a CD-ROM (or similar media) unless `NO_CDROM` is set as well.
 
 If the binary package is not generally useful, and the application must always be compiled from the source code, use `NO_PACKAGE`. For example, if the application has configuration information that is site specific hard coded into it at compile time, set `NO_PACKAGE`.
 
 Set `NO_PACKAGE` to a string describing the reason why the package cannot be generated.
 
 [[porting-restrictions-no_cdrom]]
 === `NO_CDROM`
 
 This variable alone indicates that, although we are allowed to generate binary packages, we may put neither those packages nor the port's `DISTFILES` onto a CD-ROM (or similar media) for resale. However, the binary packages and the port's `DISTFILES` will still be available via FTP/HTTP.
 
 If this variable is set along with `NO_PACKAGE`, then only the port's `DISTFILES` will be available, and only via FTP/HTTP.
 
 Set `NO_CDROM` to a string describing the reason why the port cannot be redistributed on CD-ROM. For instance, use this if the port's license is for "non-commercial" use only.
 
 [[porting-restrictions-nofetchfiles]]
 === `NOFETCHFILES`
 
 Files defined in `NOFETCHFILES` are not fetchable from any of `MASTER_SITES`. An example of such a file is when the file is supplied on CD-ROM by the vendor.
 
 Tools which check for the availability of these files on `MASTER_SITES` have to ignore these files and not report about them.
 
 [[porting-restrictions-restricted]]
 === `RESTRICTED`
 
 Set this variable alone if the application's license permits neither mirroring the application's `DISTFILES` nor distributing the binary package in any way.
 
 Do not set `NO_CDROM` or `NO_PACKAGE` along with `RESTRICTED`, since the latter variable implies the former ones.
 
 Set `RESTRICTED` to a string describing the reason why the port cannot be redistributed. Typically, this indicates that the port contains proprietary software and that the user will need to manually download the `DISTFILES`, possibly after registering for the software or agreeing to accept the terms of an EULA.
 
 [[porting-restrictions-restricted_files]]
 === `RESTRICTED_FILES`
 
 When `RESTRICTED` or `NO_CDROM` is set, this variable defaults to `${DISTFILES} ${PATCHFILES}`, otherwise it is empty. If only some of the distribution files are restricted, then set this variable to list them.
 
 [[porting-restrictions-legal_text]]
 === `LEGAL_TEXT`
 
 If the port has legal concerns not addressed by the above variables, set `LEGAL_TEXT` to a string explaining the concern. For example, if special permission was obtained for FreeBSD to redistribute the binary, this variable must indicate so.
 
 [[porting-restrictions-legal]]
 === [.filename]#/usr/ports/LEGAL# and `LEGAL`
 
 A port which sets any of the above variables must also be added to [.filename]#/usr/ports/LEGAL#. The first column is a glob which matches the restricted distfiles. The second column is the port's origin. The third column is the output of `make -VLEGAL`.
 
 [[porting-restrictions-examples]]
 === Examples
 
 The preferred way to state "the distfiles for this port must be fetched manually" is as follows:
 
 [.programlisting]
 ....
 .if !exists(${DISTDIR}/${DISTNAME}${EXTRACT_SUFX})
 IGNORE=	may not be redistributed because of licensing reasons. Please visit some-website to accept their license and download ${DISTFILES} into ${DISTDIR}
 .endif
 ....
 
 This both informs the user, and sets the proper metadata on the user's machine for use by automated programs.
 
 Note that this stanza must be preceded by an inclusion of [.filename]#bsd.port.pre.mk#.
 
 [[building]]
 == Building Mechanisms
 
 [[parallel-builds]]
 === Building Ports in Parallel
 
 The FreeBSD ports framework supports parallel building using multiple `make` sub-processes, which allows SMP systems to utilize all of their available CPU power, allowing port builds to be faster and more effective.
 
 This is achieved by passing `-jX` flag to man:make[1] running on vendor code. This is the default build behavior of ports. Unfortunately, not all ports handle parallel building well and it may be required to explicitly disable this feature by adding the `MAKE_JOBS_UNSAFE=yes` variable. It is used when a port is known to be broken with `-jX` due to race conditions causing intermittent build failures.
 
 [IMPORTANT]
 ====
 When setting `MAKE_JOBS_UNSAFE`, it is very important to explain either with a comment in the [.filename]#Makefile#, or at least in the commit message, _why_ the port does not build when enabling. Otherwise, it is almost impossible to either fix the problem, or test if it has been fixed when committing an update at a later date.
 ====
 
 [[using-make]]
 === `make`, `gmake`, and `imake`
 
 Several differing `make` implementations exist. Ported software often requires a particular implementation, like GNU`make`, known in FreeBSD as `gmake`.
 
 If the port uses GNU make, add `gmake` to `USES`.
 
 `MAKE_CMD` can be used to reference the specific command configured by the `USES` setting in the port's [.filename]#Makefile#. Only use `MAKE_CMD` within the application [.filename]#Makefile#s in `WRKSRC` to call the `make` implementation expected by the ported software.
 
 If the port is an X application that uses imake to create [.filename]##Makefile##s from [.filename]##Imakefile##s, set `USES= imake`.. See the crossref:uses[uses-imake,`USES=imake`] section of crossref:uses[uses,Using `USES` Macros] for more details.
 
 If the port's source [.filename]#Makefile# has something other than `all` as the main build target, set `ALL_TARGET` accordingly. The same goes for `install` and `INSTALL_TARGET`.
 
 [[using-configure]]
 === `configure` Script
 
 If the port uses the `configure` script to generate [.filename]#Makefile# from [.filename]#Makefile.in#, set `GNU_CONFIGURE=yes`. To give extra arguments to the `configure` script (the default argument is `--prefix=${PREFIX} --infodir=${PREFIX}/${INFO_PATH} --mandir=${MANPREFIX}/man --build=${CONFIGURE_TARGET}`), set those extra arguments in `CONFIGURE_ARGS`. Extra environment variables can be passed using `CONFIGURE_ENV`.
 
 [[using-configure-variables]]
 .Variables for Ports That Use `configure`
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Means
 
 |`GNU_CONFIGURE`
 |The port uses `configure` script to prepare build.
 
 |`HAS_CONFIGURE`
 |Same as `GNU_CONFIGURE`, except default configure target is not added to `CONFIGURE_ARGS`.
 
 |`CONFIGURE_ARGS`
 |Additional arguments passed to `configure` script.
 
 |`CONFIGURE_ENV`
 |Additional environment variables to be set for `configure` script run.
 
 |`CONFIGURE_TARGET`
 |Override default configure target. Default value is `${MACHINE_ARCH}-portbld-freebsd${OSREL}`.
 |===
 
 [[using-cmake]]
 === Using `cmake`
 
 For ports that use CMake, define `USES= cmake`.
 
 [[using-cmake-variables]]
 .Variables for Ports That Use `cmake`
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Means
 
 |`CMAKE_ARGS`
 |Port specific CMake flags to be passed to the `cmake` binary.
 
 |`CMAKE_ON`
 |For each entry in `CMAKE_ON`, an enabled boolean value is added to `CMAKE_ARGS`. See <<using-cmake-example2>>.
 
 |`CMAKE_OFF`
 |For each entry in `CMAKE_OFF`, a disabled boolean value is added to `CMAKE_ARGS`. See <<using-cmake-example2>>.
 
 |`CMAKE_BUILD_TYPE`
 |Type of build (CMake predefined build profiles). Default is `Release`, or `Debug` if `WITH_DEBUG` is set.
 
 |`CMAKE_SOURCE_PATH`
 |Path to the source directory. Default is `${WRKSRC}`.
 
 |`CONFIGURE_ENV`
 |Additional environment variables to be set for the `cmake` binary.
 |===
 
 [[using-cmake-user-variables]]
 .Variables the Users Can Define for `cmake` Builds
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Means
 
 |`CMAKE_NOCOLOR`
 |Disables color build output. Default not set, unless `BATCH` or `PACKAGE_BUILDING` are set.
 |===
 
 CMake supports these build profiles: `Debug`, `Release`, `RelWithDebInfo` and `MinSizeRel`. `Debug` and `Release` profiles respect system `\*FLAGS`, `RelWithDebInfo` and `MinSizeRel` will set `CFLAGS` to `-O2 -g` and `-Os -DNDEBUG` correspondingly. The lower-cased value of `CMAKE_BUILD_TYPE` is exported to `PLIST_SUB` and must be used if the port installs [.filename]#*.cmake# depending on the build type (see package:devel/kf5-kcrash[] for an example). Please note that some projects may define their own build profiles and/or force particular build type by setting `CMAKE_BUILD_TYPE` in [.filename]#CMakeLists.txt#. To make a port for such a project respect `CFLAGS` and `WITH_DEBUG`, the `CMAKE_BUILD_TYPE` definitions must be removed from those files.
 
 Most CMake-based projects support an out-of-source method of building. The out-of-source build for a port is the default setting. An in-source build can be requested by using the `:insource` suffix. With out-of-source builds, `CONFIGURE_WRKSRC`, `BUILD_WRKSRC` and `INSTALL_WRKSRC` will be set to `${WRKDIR}/.build` and this directory will be used to keep all files generated during configuration and build stages, leaving the source directory intact.
 
 [[using-cmake-example]]
 .`USES= cmake` Example
 [example]
 ====
 This snippet demonstrates the use of CMake for a port. `CMAKE_SOURCE_PATH` is not usually required, but can be set when the sources are not located in the top directory, or if only a subset of the project is intended to be built by the port.
 
 [.programlisting]
 ....
 USES=			cmake
 CMAKE_SOURCE_PATH=	${WRKSRC}/subproject
 ....
 
 ====
 
 [[using-cmake-example2]]
 .`CMAKE_ON` and `CMAKE_OFF`
 [example]
 ====
 When adding boolean values to `CMAKE_ARGS`, it is easier to use the `CMAKE_ON` and `CMAKE_OFF` variables instead. This:
 
 [.programlisting]
 ....
 CMAKE_ON=	VAR1 VAR2
 CMAKE_OFF=	VAR3
 ....
 
 Is equivalent to:
 
 [.programlisting]
 ....
 CMAKE_ARGS=	-DVAR1:BOOL=TRUE -DVAR2:BOOL=TRUE -DVAR3:BOOL=FALSE
 ....
 
 [IMPORTANT]
 ======
 This is only for the default values off `CMAKE_ARGS`. The helpers described in crossref:makefiles[options-cmake_bool,`OPT_CMAKE_BOOL` and `OPT_CMAKE_BOOL_OFF`] use the same semantics, but for optional values.
 ======
 
 ====
 
 [[using-scons]]
 === Using `scons`
 
 If the port uses SCons, define `USES=scons`.
 
 To make third party [.filename]#SConstruct# respect everything that is passed to SCons in the environment (that is, most importantly, `CC/CXX/CFLAGS/CXXFLAGS`), patch [.filename]#SConstruct# so build `Environment` is constructed like this:
 
 [.programlisting]
 ....
 env = Environment(**ARGUMENTS)
 ....
 
 It may be then modified with `env.Append` and `env.Replace`.
 
 [[using-cargo]]
 === Building Rust Applications with `cargo`
 
 For ports that use Cargo, define `USES=cargo`.
 
 [[using-cargo-user-variables]]
 .Variables the Users Can Define for `cargo` Builds
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Variable
 | Default
 | Description
 
 |`CARGO_CRATES`
 |
 |List of crates the port depends on. Each entry needs to have a format like `cratename-semver` for example, `libc-0.2.40`. Port maintainers can generate this list from [.filename]#Cargo.lock# using `make cargo-crates`. Manually bumping crate versions is possible but be mindful of transitive dependencies.
 
 |`CARGO_FEATURES`
 |
 |List of application features to build (space separated list). To deactivate all default features add the special token `--no-default-features` to `CARGO_FEATURES`. Manually passing it to `CARGO_BUILD_ARGS`, `CARGO_INSTALL_ARGS`, and `CARGO_TEST_ARGS` is not needed.
 
 |`CARGO_CARGOTOML`
 |`${WRKSRC}/Cargo.toml`
 |The path to the [.filename]#Cargo.toml# to use.
 
 |`CARGO_CARGOLOCK`
 |`${WRKSRC}/Cargo.lock`
 |The path to the [.filename]#Cargo.lock# to use for `make cargo-crates`. It is possible to specify more than one lock file when necessary.
 
 |`CARGO_ENV`
 |
 |A list of environment variables to pass to Cargo similar to `MAKE_ENV`.
 
 |`RUSTFLAGS`
 |
 |Flags to pass to the Rust compiler.
 
 |`CARGO_CONFIGURE`
 |`yes`
 |Use the default `do-configure`.
 
 |`CARGO_UPDATE_ARGS`
 |
 |Extra arguments to pass to Cargo during the configure phase. Valid arguments can be looked up with `cargo update --help`.
 
 |`CARGO_BUILDDEP`
 |`yes`
 |Add a build dependency on package:lang/rust[].
 
 |`CARGO_CARGO_BIN`
 |`${LOCALBASE}/bin/cargo`
 |Location of the `cargo` binary.
 
 |`CARGO_BUILD`
 |`yes`
 |Use the default `do-build`.
 
 |`CARGO_BUILD_ARGS`
 |
 |Extra arguments to pass to Cargo during the build phase. Valid arguments can be looked up with `cargo build --help`.
 
 |`CARGO_INSTALL`
 |`yes`
 |Use the default `do-install`.
 
 |`CARGO_INSTALL_ARGS`
 |
 |Extra arguments to pass to Cargo during the install phase. Valid arguments can be looked up with `cargo install --help`.
 
 |`CARGO_INSTALL_PATH`
 |`.`
 |Path to the crate to install. This is passed to `cargo install` via its `--path` argument. When multiple paths are specified `cargo install` is run multiple times.
 
 |`CARGO_TEST`
 |`yes`
 |Use the default `do-test`.
 
 |`CARGO_TEST_ARGS`
 |
 |Extra arguments to pass to Cargo during the test phase. Valid arguments can be looked up with `cargo test --help`.
 
 |`CARGO_TARGET_DIR`
 |`${WRKDIR}/target`
 |Location of the cargo output directory.
 
 |`CARGO_DIST_SUBDIR`
 |[.filename]#rust/crates#
 |Directory relative to `DISTDIR` where the crate distribution files will be stored.
 
 |`CARGO_VENDOR_DIR`
 |`${WRKSRC}/cargo-crates`
 |Location of the vendor directory where all crates will be extracted to. Try to keep this under `PATCH_WRKSRC`, so that patches can be applied easily.
 
 |`CARGO_USE_GITHUB`
 |`no`
 |Enable fetching of crates locked to specific Git commits on GitHub via `GH_TUPLE`. This will try to patch all [.filename]#Cargo.toml# under `WRKDIR` to point to the offline sources instead of fetching them from a Git repository during the build.
 
 |`CARGO_USE_GITLAB`
 |`no`
 |Same as `CARGO_USE_GITHUB` but for GitLab instances and `GL_TUPLE`.
 |===
 
 [[cargo-ex1]]
 .Creating a Port for a Simple Rust Application
 [example]
 ====
 Creating a Cargo based port is a three stage process. First we need to provide a ports template that fetches the application distribution file:
 
 [.programlisting]
 ....
 PORTNAME=	tokei
 DISTVERSIONPREFIX=	v
 DISTVERSION=	7.0.2
 CATEGORIES=	devel
 
 MAINTAINER=	tobik@FreeBSD.org
 COMMENT=	Display statistics about your code
 
 USES=		cargo
 USE_GITHUB=	yes
 GH_ACCOUNT=	Aaronepower
 
 .include <bsd.port.mk>
 ....
 
 Generate an initial [.filename]#distinfo#:
 
 [source,shell]
 ....
 % make makesum
 => Aaronepower-tokei-v7.0.2_GH0.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://codeload.github.com/Aaronepower/tokei/tar.gz/v7.0.2?dummy=/Aaronepower-tokei-v7.0.2_GH0.tar.gz
 fetch: https://codeload.github.com/Aaronepower/tokei/tar.gz/v7.0.2?dummy=/Aaronepower-tokei-v7.0.2_GH0.tar.gz: size of remote file is not known
 Aaronepower-tokei-v7.0.2_GH0.tar.gz                     45 kB  239 kBps 00m00s
 ....
 
 Now the distribution file is ready to use and we can go ahead and extract crate dependencies from the bundled [.filename]#Cargo.lock#:
 
 [source,shell]
 ....
 % make cargo-crates
 CARGO_CRATES=   aho-corasick-0.6.4 \
                 ansi_term-0.11.0 \
                 arrayvec-0.4.7 \
                 atty-0.2.9 \
                 bitflags-1.0.1 \
                 byteorder-1.2.2 \
                 [...]
 ....
 
 The output of this command needs to be pasted directly into the Makefile:
 
 [.programlisting]
 ....
 PORTNAME=	tokei
 DISTVERSIONPREFIX=	v
 DISTVERSION=	7.0.2
 CATEGORIES=	devel
 
 MAINTAINER=	tobik@FreeBSD.org
 COMMENT=	Display statistics about your code
 
 USES=		cargo
 USE_GITHUB=	yes
 GH_ACCOUNT=	Aaronepower
 
 CARGO_CRATES=   aho-corasick-0.6.4 \
                 ansi_term-0.11.0 \
                 arrayvec-0.4.7 \
                 atty-0.2.9 \
                 bitflags-1.0.1 \
                 byteorder-1.2.2 \
                 [...]
 
 .include <bsd.port.mk>
 ....
 
 [.filename]#distinfo# needs to be regenerated to contain all the crate distribution files:
 
 [source,shell]
 ....
 % make makesum
 => rust/crates/aho-corasick-0.6.4.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://crates.io/api/v1/crates/aho-corasick/0.6.4/download?dummy=/rust/crates/aho-corasick-0.6.4.tar.gz
 rust/crates/aho-corasick-0.6.4.tar.gz         100% of   24 kB 6139 kBps 00m00s
 => rust/crates/ansi_term-0.11.0.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://crates.io/api/v1/crates/ansi_term/0.11.0/download?dummy=/rust/crates/ansi_term-0.11.0.tar.gz
 rust/crates/ansi_term-0.11.0.tar.gz           100% of   16 kB   21 MBps 00m00s
 => rust/crates/arrayvec-0.4.7.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://crates.io/api/v1/crates/arrayvec/0.4.7/download?dummy=/rust/crates/arrayvec-0.4.7.tar.gz
 rust/crates/arrayvec-0.4.7.tar.gz             100% of   22 kB 3237 kBps 00m00s
 => rust/crates/atty-0.2.9.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://crates.io/api/v1/crates/atty/0.2.9/download?dummy=/rust/crates/atty-0.2.9.tar.gz
 rust/crates/atty-0.2.9.tar.gz                 100% of 5898  B   81 MBps 00m00s
 => rust/crates/bitflags-1.0.1.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 [...]
 ....
 
 The port is now ready for a test build and further adjustments like creating a plist, writing a description, adding license information, options, etc. as normal.
 
 If you are not testing your port in a clean environment like with Poudriere, remember to run `make clean` before any testing.
 ====
 
 [[cargo-ex2]]
 .Enabling Additional Application Features
 [example]
 ====
 Some applications define additional features in their [.filename]#Cargo.toml#. They can be compiled in by setting `CARGO_FEATURES` in the port.
 
 Here we enable Tokei's `json` and `yaml` features:
 
 [.programlisting]
 ....
 CARGO_FEATURES=	json yaml
 ....
 
 ====
 
 [[cargo-ex4]]
 .Encoding Application Features As Port Options
 [example]
 ====
 An example `[features]` section in [.filename]#Cargo.toml# could look like this:
 
 [.programlisting]
 ....
 [features]
 pulseaudio_backend = ["librespot-playback/pulseaudio-backend"]
 portaudio_backend = ["librespot-playback/portaudio-backend"]
 default = ["pulseaudio_backend"]
 ....
 
 `pulseaudio_backend` is a default feature. It is always enabled unless we explicitly turn off default features by adding `--no-default-features` to `CARGO_FEATURES`. Here we turn the `portaudio_backend` and `pulseaudio_backend` features into port options:
 
 [.programlisting]
 ....
 CARGO_FEATURES=	--no-default-features
 
 OPTIONS_DEFINE=	PORTAUDIO PULSEAUDIO
 
 PORTAUDIO_VARS=		CARGO_FEATURES+=portaudio_backend
 PULSEAUDIO_VARS=	CARGO_FEATURES+=pulseaudio_backend
 ....
 
 ====
 
 [[cargo-ex3]]
 .Listing Crate Licenses
 [example]
 ====
 Crates have their own licenses. It is important to know what they are when adding a `LICENSE` block to the port (see crossref:makefiles[licenses,Licenses]). The helper target `cargo-crates-licenses` will try to list all the licenses of all crates defined in `CARGO_CRATES`.
 
 [source,shell]
 ....
 % make cargo-crates-licenses
 aho-corasick-0.6.4  Unlicense/MIT
 ansi_term-0.11.0    MIT
 arrayvec-0.4.7      MIT/Apache-2.0
 atty-0.2.9          MIT
 bitflags-1.0.1      MIT/Apache-2.0
 byteorder-1.2.2     Unlicense/MIT
 [...]
 ....
 
 [NOTE]
 ======
 The license names `make cargo-crates-licenses` outputs are SPDX 2.1 licenses expression which do not match the license names defined in the ports framework. They need to be translated to the names from crossref:makefiles[licenses-license-list,Predefined License List].
 ======
 
 ====
 
 [[using-meson]]
 === Using `meson`
 
 For ports that use Meson, define `USES=meson`.
 
 [[using-meson-variables]]
 .Variables for Ports That Use `meson`
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 
 |`MESON_ARGS`
 |Port specific Meson flags to be passed to the `meson` binary.
 
 |`MESON_BUILD_DIR`
 |Path to the build directory relative to `WRKSRC`. Default is `_build`.
 |===
 
 [[using-meson-example]]
 .`USES=meson` Example
 [example]
 ====
 This snippet demonstrates the use of Meson for a port.
 
 [.programlisting]
 ....
 USES=		meson
 MESON_ARGS=	-Dfoo=enabled
 ....
 
 ====
 
 [[using-go]]
 === Building Go Applications
 
 For ports that use Go, define `USES=go`. Refer to crossref:uses[uses-go,`go`] for a list of variables that can be set to control the build process.
 
 [[go-ex1]]
 .Creating a Port for a Go Modules Based Application
 [example]
 ====
 In most cases, it is sufficient to set the `GO_MODULE` variable to the value specified by the `module` directive in `go.mod`:
 
 [.programlisting]
 ....
 PORTNAME=       hey
 PORTVERSION=    0.1.4
 DISTVERSIONPREFIX=      v
 CATEGORIES=     benchmarks
 
 MAINTAINER=     dmgk@FreeBSD.org
 COMMENT=        Tiny program that sends some load to a web application
 
 LICENSE=        APACHE20
 LICENSE_FILE=   ${WRKSRC}/LICENSE
 
 USES=           go:modules
 GO_MODULE=      github.com/rakyll/hey
 
 PLIST_FILES=    bin/hey
 
 .include <bsd.port.mk>
 ....
 
 If the "easy" way is not adequate or more control over dependencies is needed, the full porting process is described below.
 
 Creating a Go based port is a five stage process. First we need to provide a ports template that fetches the application distribution file:
 
 [.programlisting]
 ....
 PORTNAME=	ghq
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.12.5
 CATEGORIES=	devel
 
 MAINTAINER=	tobik@FreeBSD.org
 COMMENT=	Remote repository management made easy
 
 USES=		go:modules
 USE_GITHUB=	yes
 GH_ACCOUNT=	motemen
 
 .include <bsd.port.mk>
 ....
 
 Generate an initial [.filename]#distinfo#:
 
 [source,shell]
 ....
 % make makesum
 ===>  License MIT accepted by the user
 => motemen-ghq-v0.12.5_GH0.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://codeload.github.com/motemen/ghq/tar.gz/v0.12.5?dummy=/motemen-ghq-v0.12.5_GH0.tar.gz
 fetch: https://codeload.github.com/motemen/ghq/tar.gz/v0.12.5?dummy=/motemen-ghq-v0.12.5_GH0.tar.gz: size of remote file is not known
 motemen-ghq-v0.12.5_GH0.tar.gz                          32 kB  177 kBps    00s
 ....
 
 Now the distribution file is ready to use and we can extract the required Go module dependencies. This step requires having package:ports-mgmt/modules2tuple[] installed:
 
 [source,shell]
 ....
 % make gomod-vendor
 [...]
 GH_TUPLE=	\
 		Songmu:gitconfig:v0.0.2:songmu_gitconfig/vendor/github.com/Songmu/gitconfig \
 		daviddengcn:go-colortext:186a3d44e920:daviddengcn_go_colortext/vendor/github.com/daviddengcn/go-colortext \
 		go-yaml:yaml:v2.2.2:go_yaml_yaml/vendor/gopkg.in/yaml.v2 \
 		golang:net:3ec191127204:golang_net/vendor/golang.org/x/net \
 		golang:sync:112230192c58:golang_sync/vendor/golang.org/x/sync \
 		golang:xerrors:3ee3066db522:golang_xerrors/vendor/golang.org/x/xerrors \
 		motemen:go-colorine:45d19169413a:motemen_go_colorine/vendor/github.com/motemen/go-colorine \
 		urfave:cli:v1.20.0:urfave_cli/vendor/github.com/urfave/cli
 ....
 
 The output of this command needs to be pasted directly into the Makefile:
 
 [.programlisting]
 ....
 PORTNAME=	ghq
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.12.5
 CATEGORIES=	devel
 
 MAINTAINER=	tobik@FreeBSD.org
 COMMENT=	Remote repository management made easy
 
 USES=		go:modules
 USE_GITHUB=	yes
 GH_ACCOUNT=	motemen
 GH_TUPLE=	Songmu:gitconfig:v0.0.2:songmu_gitconfig/vendor/github.com/Songmu/gitconfig \
 		daviddengcn:go-colortext:186a3d44e920:daviddengcn_go_colortext/vendor/github.com/daviddengcn/go-colortext \
 		go-yaml:yaml:v2.2.2:go_yaml_yaml/vendor/gopkg.in/yaml.v2 \
 		golang:net:3ec191127204:golang_net/vendor/golang.org/x/net \
 		golang:sync:112230192c58:golang_sync/vendor/golang.org/x/sync \
 		golang:xerrors:3ee3066db522:golang_xerrors/vendor/golang.org/x/xerrors \
 		motemen:go-colorine:45d19169413a:motemen_go_colorine/vendor/github.com/motemen/go-colorine \
 		urfave:cli:v1.20.0:urfave_cli/vendor/github.com/urfave/cli
 
 .include <bsd.port.mk>
 ....
 
 [.filename]#distinfo# needs to be regenerated to contain all the distribution files:
 
 [source,shell]
 ....
 % make makesum
 => Songmu-gitconfig-v0.0.2_GH0.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://codeload.github.com/Songmu/gitconfig/tar.gz/v0.0.2?dummy=/Songmu-gitconfig-v0.0.2_GH0.tar.gz
 fetch: https://codeload.github.com/Songmu/gitconfig/tar.gz/v0.0.2?dummy=/Songmu-gitconfig-v0.0.2_GH0.tar.gz: size of remote file is not known
 Songmu-gitconfig-v0.0.2_GH0.tar.gz                    5662  B  936 kBps    00s
 => daviddengcn-go-colortext-186a3d44e920_GH0.tar.gz doesn't seem to exist in /usr/ports/distfiles/.
 => Attempting to fetch https://codeload.github.com/daviddengcn/go-colortext/tar.gz/186a3d44e920?dummy=/daviddengcn-go-colortext-186a3d44e920_GH0.tar.gz
 fetch: https://codeload.github.com/daviddengcn/go-colortext/tar.gz/186a3d44e920?dummy=/daviddengcn-go-colortext-186a3d44e920_GH0.tar.gz: size of remote file is not known
 daviddengcn-go-colortext-186a3d44e920_GH0.tar.        4534  B 1098 kBps    00s
 [...]
 ....
 
 The port is now ready for a test build and further adjustments like creating a plist, writing a description, adding license information, options, etc. as normal.
 
 If you are not testing your port in a clean environment like with Poudriere, remember to run `make clean` before any testing.
 ====
 
 [[go-ex2]]
 .Setting Output Binary Name or Installation Path
 [example]
 ====
 Some ports need to install the resulting binary under a different name or to a path other than the default `${PREFIX}/bin`. This can be done by using `GO_TARGET` tuple syntax, for example:
 
 [.programlisting]
 ....
 GO_TARGET=  ./cmd/ipfs:ipfs-go
 ....
 
 will install `ipfs` binary as `${PREFIX}/bin/ipfs-go` and
 
 [.programlisting]
 ....
 GO_TARGET=  ./dnscrypt-proxy:${PREFIX}/sbin/dnscrypt-proxy
 ....
 
 will install `dnscrypt-proxy` to `${PREFIX}/sbin`.
 ====
 
 [[using-cabal]]
 === Building Haskell Applications with `cabal`
 
 For ports that use Cabal, build system defines `USES=cabal`. Refer to crossref:uses[uses-cabal,`cabal`] for a list of variables that can be set to control the build process.
 
 [[cabal-ex1]]
 .Creating a Port for a Hackage-hosted Haskell Application
 [example]
 ====
 When preparing a Haskell Cabal port, the package:devel/hs-cabal-install[] program is required, so make sure it is installed beforehand. First we need to define common ports variables that allows cabal-install to fetch the package distribution file:
 
 [.programlisting]
 ....
 PORTNAME=	ShellCheck
 DISTVERSION=	0.6.0
 CATEGORIES=	devel
 
 MAINTAINER=	haskell@FreeBSD.org
 COMMENT=	Shell script analysis tool
 
 USES=		cabal
 
 .include <bsd.port.mk>
 ....
 
 This minimal Makefile allows us to fetch the distribution file:
 
 [source,shell]
 ....
 % make cabal-extract
 [...]
 Downloading the latest package list from hackage.haskell.org
 cabal get ShellCheck-0.6.0
 Downloading  ShellCheck-0.6.0
 Downloaded   ShellCheck-0.6.0
 Unpacking to ShellCheck-0.6.0/
 ....
 
 Now we have ShellCheck.cabal package description file, which allows us to fetch all package's dependencies, including transitive ones:
 
 [source,shell]
 ....
 % make cabal-extract-deps
 [...]
 Resolving dependencies...
 Downloading  base-orphans-0.8.2
 Downloaded   base-orphans-0.8.2
 Downloading  primitive-0.7.0.0
 Starting     base-orphans-0.8.2 (lib)
 Building     base-orphans-0.8.2 (lib)
 Downloaded   primitive-0.7.0.0
 Downloading  dlist-0.8.0.7
 [...]
 ....
 
 As a side effect, the package's dependencies are also compiled, so the command may take some time. Once done, a list of required dependencies can generated:
 
 [source,shell]
 ....
 % make make-use-cabal
 USE_CABAL=QuickCheck-2.12.6.1 \
 hashable-1.3.0.0 \
 integer-logarithms-1.0.3 \
 [...]
 ....
 
 Haskell packages may contain revisions, just like FreeBSD ports. Revisions can affect only [.filename]#.cabal# files, but it is still important to pull them in. To check `USE_CABAL` items for available revision updates, run following command:
 
 [source,shell]
 ....
 % make make-use-cabal-revs
 USE_CABAL=QuickCheck-2.12.6.1_1 \
 hashable-1.3.0.0 \
 integer-logarithms-1.0.3_2 \
 [...]
 ....
 
 Note additional version numbers after `_` symbol. Put newly generated `USE_CABAL` list instead of an old one.
 
 Finally, [.filename]#distinfo# needs to be regenerated to contain all the distribution files:
 
 [source,shell]
 ....
 % make makesum
 => ShellCheck-0.6.0.tar.gz doesn't seem to exist in /usr/local/poudriere/ports/git/distfiles/cabal.
 => Attempting to fetch https://hackage.haskell.org/package/ShellCheck-0.6.0/ShellCheck-0.6.0.tar.gz
 ShellCheck-0.6.0.tar.gz                                136 kB  642 kBps    00s
 => QuickCheck-2.12.6.1/QuickCheck-2.12.6.1.tar.gz doesn't seem to exist in /usr/local/poudriere/ports/git/distfiles/cabal.
 => Attempting to fetch https://hackage.haskell.org/package/QuickCheck-2.12.6.1/QuickCheck-2.12.6.1.tar.gz
 QuickCheck-2.12.6.1/QuickCheck-2.12.6.1.tar.gz          65 kB  361 kBps    00s
 [...]
 ....
 
 The port is now ready for a test build and further adjustments like creating a plist, writing a description, adding license information, options, etc. as normal.
 
 If you are not testing your port in a clean environment like with Poudriere, remember to run `make clean` before any testing.
 ====
 
 [[using-autotools]]
 == Using GNU Autotools
 
 If a port needs any of the GNU Autotools software, add `USES=autoreconf`. See crossref:uses[uses-autoreconf,`autoreconf`] for more information.
 
 [[using-gettext]]
 == Using GNU `gettext`
 
 [[using-gettext-basic]]
 === Basic Usage
 
 If the port requires `gettext`, set `USES= gettext`, and the port will inherit a dependency on [.filename]#libintl.so# from package:devel/gettext[]. Other values for `gettext` usage are listed in crossref:uses[uses-gettext,`USES=gettext`].
 
 A rather common case is a port using `gettext` and `configure`. Generally, GNU `configure` should be able to locate `gettext` automatically.
 
 [.programlisting]
 ....
 USES=	gettext
 GNU_CONFIGURE=	yes
 ....
 
 If it ever fails to, hints at the location of `gettext` can be passed in `CPPFLAGS` and `LDFLAGS` using `localbase` as follows:
 
 [.programlisting]
 ....
 USES=	gettext localbase:ldflags
 GNU_CONFIGURE=	yes
 ....
 
 [[using-gettext-optional]]
 === Optional Usage
 
 Some software products allow for disabling NLS. For example, through passing `--disable-nls` to `configure`. In that case, the port must use `gettext` conditionally, depending on the status of the `NLS` option. For ports of low to medium complexity, use this idiom:
 
 [.programlisting]
 ....
 GNU_CONFIGURE=		yes
 
 OPTIONS_DEFINE=		NLS
 OPTIONS_SUB=		yes
 
 NLS_USES=		gettext
 NLS_CONFIGURE_ENABLE=	nls
 
 .include <bsd.port.mk>
 ....
 
 Or using the older way of using options:
 
 [.programlisting]
 ....
 GNU_CONFIGURE=		yes
 
 OPTIONS_DEFINE=		NLS
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MNLS}
 USES+=			gettext
 PLIST_SUB+=		NLS=""
 .else
 CONFIGURE_ARGS+=	--disable-nls
 PLIST_SUB+=		NLS="@comment "
 .endif
 
 .include <bsd.port.mk>
 ....
 
 The next item on the to-do list is to arrange so that the message catalog files are included in the packing list conditionally. The [.filename]#Makefile# part of this task is already provided by the idiom. It is explained in the section on  crossref:plist[plist-sub,advanced [.filename]#pkg-plist# practices]. In a nutshell, each occurrence of `%%NLS%%` in [.filename]#pkg-plist# will be replaced by "`@comment `" if NLS is disabled, or by a null string if NLS is enabled. Consequently, the lines prefixed by `%%NLS%%` will become mere comments in the final packing list if NLS is off; otherwise the prefix will be just left out. Then insert `%%NLS%%` before each path to a message catalog file in [.filename]#pkg-plist#. For example:
 
 [.programlisting]
 ....
 %%NLS%%share/locale/fr/LC_MESSAGES/foobar.mo
 %%NLS%%share/locale/no/LC_MESSAGES/foobar.mo
 ....
 
 In high complexity cases, more advanced techniques may be needed, such as crossref:plist[plist-dynamic,dynamic packing list generation].
 
 [[using-gettext-catalog-directories]]
 === Handling Message Catalog Directories
 
 There is a point to note about installing message catalog files. The target directories for them, which reside under [.filename]#LOCALBASE/share/locale#, must not be created and removed by a port. The most popular languages have their respective directories listed in [.filename]#PORTSDIR/Templates/BSD.local.dist#. The directories for many other languages are governed by the package:devel/gettext[] port. Consult its [.filename]#pkg-plist# and see whether the port is going to install a message catalog file for a unique language.
 
 [[using-perl]]
 == Using Perl
 
 If `MASTER_SITES` is set to `CPAN`, the correct subdirectory is usually selected automatically. If the default subdirectory is wrong, `CPAN/Module` can be used to change it. `MASTER_SITES` can also be set to the old `MASTER_SITE_PERL_CPAN`, then the preferred value of `MASTER_SITE_SUBDIR` is the top-level hierarchy name. For example, the recommended value for `p5-Module-Name` is `Module`. The top-level hierarchy can be examined at http://cpan.org/modules/by-module/[cpan.org]. This keeps the port working when the author of the module changes.
 
 The exception to this rule is when the relevant directory does not exist or the distfile does not exist in that directory. In such case, using author's id as `MASTER_SITE_SUBDIR` is allowed. The `CPAN:AUTHOR` macro can be used, which will be translated to the hashed author directory. For example, `CPAN:AUTHOR` will be converted to `authors/id/A/AU/AUTHOR`.
 
 When a port needs Perl support, it must set `USES=perl5` with the optional `USE_PERL5` described in crossref:uses[uses-perl5,the perl5 USES description].
 
 [[using-perl-variables]]
 .Read-Only Variables for Ports That Use Perl
 [cols="1,1", frame="none", options="header"]
 |===
 | Read only variables
 | Means
 
 |`PERL`
 |The full path of the Perl 5 interpreter, either in the system or installed from a port, but without the version number. Use this when the software needs the path to the Perl interpreter. To replace "``#!``"lines in scripts, use crossref:uses[uses-shebangfix,`shebangfix`].
 
 |`PERL_VERSION`
 |The full version of Perl installed (for example, `5.8.9`).
 
 |`PERL_LEVEL`
 |The installed Perl version as an integer of the form `MNNNPP` (for example, `500809`).
 
 |`PERL_ARCH`
 |Where Perl stores architecture dependent libraries. Defaults to `${ARCH}-freebsd`.
 
 |`PERL_PORT`
 |Name of the Perl port that is installed (for example, `perl5`).
 
 |`SITE_PERL`
 |Directory name where site specific Perl packages go. This value is added to `PLIST_SUB`.
 |===
 
 [NOTE]
 ====
 Ports of Perl modules which do not have an official website must link to `cpan.org` in the WWW line of [.filename]#pkg-descr#. The preferred URL form is `http://search.cpan.org/dist/Module-Name/` (including the trailing slash).
 ====
 
 [NOTE]
 ====
 Do not use `${SITE_PERL}` in dependency declarations. Doing so assumes that [.filename]#perl5.mk# has been included, which is not always true. Ports depending on this port will have incorrect dependencies if this port's files move later in an upgrade. The right way to declare Perl module dependencies is shown in the example below.
 ====
 
 [[use-perl-dependency-example]]
 .Perl Dependency Example
 [example]
 ====
 [.programlisting]
 ....
 p5-IO-Tee>=0.64:devel/p5-IO-Tee
 ....
 
 ====
 
 For Perl ports that install manual pages, the macro `PERL5_MAN3` and `PERL5_MAN1` can be used inside [.filename]#pkg-plist#. For example,
 
 [.programlisting]
 ....
 lib/perl5/5.14/man/man1/event.1.gz
 lib/perl5/5.14/man/man3/AnyEvent::I3.3.gz
 ....
 
 can be replaced with
 
 [.programlisting]
 ....
 %%PERL5_MAN1%%/event.1.gz
 %%PERL5_MAN3%%/AnyEvent::I3.3.gz
 ....
 
 [NOTE]
 ====
 There are no `PERL5_MAN_x_` macros for the other sections (_x_ in `2` and `4` to `9`) because those get installed in the regular directories.
 ====
 
 [[use-perl-ex-build]]
 .A Port Which Only Requires Perl to Build
 [example]
 ====
 As the default USE_PERL5 value is build and run, set it to:
 
 [.programlisting]
 ....
 USES=		perl5
 USE_PERL5=	build
 ....
 
 ====
 
 [[use-perl-ex-patch]]
 .A Port Which Also Requires Perl to Patch
 [example]
 ====
 From time to time, using man:sed[1] for patching is not enough. When using man:perl[1] is easier, use:
 
 [.programlisting]
 ....
 USES=		perl5
 USE_PERL5=	patch build run
 ....
 
 ====
 
 [[use-perl-ex-configure]]
 .A Perl Module Which Needs `ExtUtils::MakeMaker` to Build
 [example]
 ====
 Most Perl modules come with a [.filename]#Makefile.PL# configure script. In this case, set:
 
 [.programlisting]
 ....
 USES=		perl5
 USE_PERL5=	configure
 ....
 
 ====
 
 [[use-perl-ex-modbuild]]
 .A Perl Module Which Needs `Module::Build` to Build
 [example]
 ====
 When a Perl module comes with a [.filename]#Build.PL# configure script, it can require Module::Build, in which case, set
 
 [.programlisting]
 ....
 USES=		perl5
 USE_PERL5=	modbuild
 ....
 
 If it instead requires Module::Build::Tiny, set
 
 [.programlisting]
 ....
 USES=		perl5
 USE_PERL5=	modbuildtiny
 ....
 
 ====
 
 [[using-x11]]
 == Using X11
 
 [[x11-variables]]
 === X.Org Components
 
 The X11 implementation available in The Ports Collection is X.Org. If the application depends on X components, add `USES= xorg` and set `USE_XORG` to the list of required components. A full list can be found in crossref:uses[uses-xorg,`xorg`].
 
 The Mesa Project is an effort to provide free OpenGL implementation. To specify a dependency on various components of this project, use `USES= gl` and `USE_GL`. See crossref:uses[uses-gl,`gl`] for a full list of available components. For backwards compatibility, the value of `yes` maps to `glu`.
 
 [[use-xorg-example]]
 .`USE_XORG` Example
 [example]
 ====
 [.programlisting]
 ....
 USES=		gl xorg
 USE_GL=		glu
 USE_XORG=	xrender xft xkbfile xt xaw
 ....
 
 ====
 
 [[using-xorg-variables]]
 .Variables for Ports That Use X
 [cols="1,1", frame="none"]
 |===
 |`USES= imake`
 |The port uses `imake`.
 
 |`XMKMF`
 |Set to the path of `xmkmf` if not in the `PATH`. Defaults to `xmkmf -a`.
 |===
 
 [[using-x11-vars]]
 .Using X11-Related Variables
 [example]
 ====
 [.programlisting]
 ....
 # Use some X11 libraries
 USES=		xorg
 USE_XORG=	x11 xpm
 ....
 
 ====
 
 [[x11-motif]]
 === Ports That Require Motif
 
 If the port requires a Motif library, define `USES= motif` in the [.filename]#Makefile#. Default Motif implementation is package:x11-toolkits/open-motif[]. Users can choose package:x11-toolkits/lesstif[] instead by setting `WANT_LESSTIF` in their [.filename]#make.conf#.
 
 `MOTIFLIB` will be set by [.filename]#motif.mk# to reference the appropriate Motif library. Please patch the source of the port to use `${MOTIFLIB}` wherever the Motif library is referenced in the original [.filename]#Makefile# or [.filename]#Imakefile#.
 
 There are two common cases:
 
 * If the port refers to the Motif library as `-lXm` in its [.filename]#Makefile# or [.filename]#Imakefile#, substitute `${MOTIFLIB}` for it.
 * If the port uses `XmClientLibs` in its [.filename]#Imakefile#, change it to `${MOTIFLIB} ${XTOOLLIB} ${XLIB}`.
 
 Note that `MOTIFLIB` (usually) expands to `-L/usr/local/lib -lXm -lXp` or `/usr/local/lib/libXm.a`, so there is no need to add `-L` or `-l` in front.
 
 [[x11-fonts]]
 === X11 Fonts
 
 If the port installs fonts for the X Window System, put them in [.filename]#LOCALBASE/lib/X11/fonts/local#.
 
 [[x11-fake-display]]
 === Getting a Fake `DISPLAY` with Xvfb
 
 Some applications require a working X11 display for compilation to succeed. This poses a problem for machines that operate headless. When this variable is used, the build infrastructure will start the virtual framebuffer X server. The working `DISPLAY` is then passed to the build. See crossref:uses[uses-display,`USES=display`] for the possible arguments.
 
 [.programlisting]
 ....
 USES=	display
 ....
 
 
 [[desktop-entries]]
 === Desktop Entries
 
 Desktop entries (http://standards.freedesktop.org/desktop-entry-spec/latest/[a Freedesktop standard]) provide a way to automatically adjust desktop features when a new program is installed, without requiring user intervention. For example, newly-installed programs automatically appear in the application menus of compatible desktop environments. Desktop entries originated in the GNOME desktop environment, but are now a standard and also work with KDE and Xfce. This bit of automation provides a real benefit to the user, and desktop entries are encouraged for applications which can be used in a desktop environment.
 
 [[desktop-entries-predefined]]
 ==== Using Predefined [.filename]#.desktop# Files
 
 Ports that include predefined [.filename]#*.desktop# must include those files in [.filename]#pkg-plist# and install them in the [.filename]#$LOCALBASE/share/applications# directory. The crossref:makefiles[install-macros,`INSTALL_DATA` macro] is useful for installing these files.
 
 [[updating-desktop-database]]
 ==== Updating Desktop Database
 
 If a port has a MimeType entry in its [.filename]#portname.desktop#, the desktop database must be updated after install and deinstall. To do this, define `USES`= desktop-file-utils.
 
 [[desktop-entries-macro]]
 ==== Creating Desktop Entries with `DESKTOP_ENTRIES`
 
 Desktop entries can be easily created for applications by using `DESKTOP_ENTRIES`. A file named [.filename]#name.desktop# will be created, installed, and added to [.filename]#pkg-plist# automatically. Syntax is:
 
 [.programlisting]
 ....
 DESKTOP_ENTRIES=	"NAME" "COMMENT" "ICON" "COMMAND" "CATEGORY" StartupNotify
 ....
 
 The list of possible categories is available on the http://standards.freedesktop.org/menu-spec/latest/apa.html[Freedesktop website]. `StartupNotify` indicates whether the application is compatible with _startup notifications_. These are typically a graphic indicator like a clock that appear at the mouse pointer, menu, or panel to give the user an indication when a program is starting. A program that is compatible with startup notifications clears the indicator after it has started. Programs that are not compatible with startup notifications would never clear the indicator (potentially confusing and infuriating the user), and must have `StartupNotify` set to `false` so the indicator is not shown at all.
 
 Example:
 
 [.programlisting]
 ....
 DESKTOP_ENTRIES=	"ToME" "Roguelike game based on JRR Tolkien's work" \
 			"${DATADIR}/xtra/graf/tome-128.png" \
 			"tome -v -g" "Application;Game;RolePlaying;" \
 			false
 ....
 
 
 [[using-gnome]]
 == Using GNOME
 
 [[using-gnome-introduction]]
 === Introduction
 
 This chapter explains the GNOME framework as used by ports. The framework can be loosely divided into the base components, GNOME desktop components, and a few special macros that simplify the work of port maintainers.
 
 [[use-gnome]]
 === Using `USE_GNOME`
 
 Adding this variable to the port allows the use of the macros and components defined in [.filename]#bsd.gnome.mk#. The code in [.filename]#bsd.gnome.mk# adds the needed build-time, run-time or library dependencies or the handling of special files. GNOME applications under FreeBSD use the `USE_GNOME` infrastructure. Include all the needed components as a space-separated list. The `USE_GNOME` components are divided into these virtual lists: basic components, GNOME 3 components and legacy components. If the port needs only GTK3 libraries, this is the shortest way to define it:
 
 [.programlisting]
 ....
 USE_GNOME=	gtk30
 ....
 
 `USE_GNOME` components automatically add the dependencies they need. Please see <<gnome-components>> for an exhaustive list of all `USE_GNOME` components and which other components they imply and their dependencies.
 
 Here is an example [.filename]#Makefile# for a GNOME port that uses many of the techniques outlined in this document. Please use it as a guide for creating new ports.
 
 [.programlisting]
 ....
 # $FreeBSD$
 
 PORTNAME=	regexxer
 DISTVERSION=	0.10
 CATEGORIES=	devel textproc gnome
 MASTER_SITES=	GNOME
 
 MAINTAINER=	kwm@FreeBSD.org
 COMMENT=	Interactive tool for performing search and replace operations
 
 USES=		gettext gmake localbase:ldflags pathfix pkgconfig tar:xz
 GNU_CONFIGURE=	yes
 USE_GNOME=	gnomeprefix intlhack gtksourceviewmm3
 INSTALLS_ICONS=	yes
 
 GLIB_SCHEMAS=	org.regexxer.gschema.xml
 
 .include <bsd.port.mk>
 ....
 
 [NOTE]
 ====
 The `USE_GNOME` macro without any arguments does not add any dependencies to the port. `USE_GNOME` cannot be set after [.filename]#bsd.port.pre.mk#.
 ====
 
 [[using-gnome-variables]]
 === Variables
 
 This section explains which macros are available and how they are used. Like they are used in the above example. The <<gnome-components>> has a more in-depth explanation. `USE_GNOME` has to be set for these macros to be of use.
 
 `INSTALLS_ICONS`::
 GTK+ ports which install Freedesktop-style icons to [.filename]#${LOCALBASE}/share/icons# should use this macro to ensure that the icons are cached and will display correctly. The cache file is named [.filename]#icon-theme.cache#. Do not include that file in [.filename]#pkg-plist#. This macro handles that automatically. This macro is not needed for Qt, which uses an internal method.
 
 `GLIB_SCHEMAS`::
 List of all the glib schema files the port installs. The macro will add the files to the port plist and handle the registration of these files on install and deinstall.
 +
 The glib schema files are written in XML and end with the [.filename]#gschema.xml# extension. They are installed in the [.filename]#share/glib-2.0/schemas/# directory. These schema files contain all application config values with their default settings. The actual database used by the applications is built by glib-compile-schema, which is run by the `GLIB_SCHEMAS` macro.
 +
 [.programlisting]
 ....
 GLIB_SCHEMAS=foo.gschema.xml
 ....
 +
 [NOTE]
 ====
 Do not add glib schemas to the [.filename]#pkg-plist#. If they are listed in [.filename]#pkg-plist#, they will not be registered and the applications might not work properly.
 ====
 
 `GCONF_SCHEMAS`::
 List all the gconf schema files. The macro will add the schema files to the port plist and will handle their registration on install and deinstall.
 +
 GConf is the XML-based database that virtually all GNOME applications use for storing their settings. These files are installed into the [.filename]#etc/gconf/schemas# directory. This database is defined by installed schema files that are used to generate [.filename]#%gconf.xml# key files. For each schema file installed by the port, there must be an entry in the [.filename]#Makefile#:
 +
 [.programlisting]
 ....
 GCONF_SCHEMAS=my_app.schemas my_app2.schemas my_app3.schemas
 ....
 +
 [NOTE]
 ====
 Gconf schemas are listed in the `GCONF_SCHEMAS` macro rather than [.filename]#pkg-plist#. If they are listed in [.filename]#pkg-plist#, they will not be registered and the applications might not work properly.
 ====
 
 `INSTALLS_OMF`::
 Open Source Metadata Framework (OMF) files are commonly used by GNOME 2 applications. These files contain the application help file information, and require special processing by ScrollKeeper/rarian. To properly register OMF files when installing GNOME applications from packages, make sure that `omf` files are listed in `pkg-plist` and that the port [.filename]#Makefile# has `INSTALLS_OMF` defined:
 +
 [.programlisting]
 ....
 INSTALLS_OMF=yes
 ....
 +
 When set, [.filename]#bsd.gnome.mk# automatically scans [.filename]#pkg-plist# and adds appropriate `@exec` and `@unexec` directives for each [.filename]#.omf# to track in the OMF registration database.
 
 [[gnome-components]]
 == GNOME Components
 
 For further help with a GNOME port, look at some of the link:https://www.FreeBSD.org/ports/gnome.html[existing ports] for examples. The link:https://www.FreeBSD.org/gnome/[FreeBSD GNOME page] has contact information if more help is needed. The components are divided into GNOME components that are currently in use and legacy components. If the component supports argument, they are listed between parenthesis in the description. The first is the default. "Both" is shown if the component defaults to adding to both build and run dependencies.
 
 [[gnome-components-list]]
 .GNOME Components
 [cols="1,1,1", options="header"]
 |===
 | Component
 | Associated program
 | Description
 
 |`atk`
 |accessibility/atk
 |Accessibility toolkit (ATK)
 
 |`atkmm`
 |accessibility/atkmm
 |c++ bindings for atk
 
 |`cairo`
 |graphics/cairo
 |Vector graphics library with cross-device output support
 
 |`cairomm`
 |graphics/cairomm
 |c++ bindings for cairo
 
 |`dconf`
 |devel/dconf
 |Configuration database system (both, build, run)
 
 |`evolutiondataserver3`
 |databases/evolution-data-server
 |Data backends for the Evolution integrated mail/PIM suite
 
 |`gdkpixbuf2`
 |graphics/gdk-pixbuf2
 |Graphics library for GTK+
 
 |`glib20`
 |devel/glib20
 |GNOME core library `glib20`
 
 |`glibmm`
 |devel/glibmm
 |c++ bindings for glib20
 
 |`gnomecontrolcenter3`
 |sysutils/gnome-control-center
 |GNOME 3 Control Center
 
 |`gnomedesktop3`
 |x11/gnome-desktop
 |GNOME 3 desktop UI library
 
 |`gsound`
 |audio/gsound
 |GObject library for playing system sounds (both, build, run)
 
 |`gtk-update-icon-cache`
 |graphics/gtk-update-icon-cache
 |Gtk-update-icon-cache utility from the Gtk+ toolkit
 
 |`gtk20`
 |x11-toolkits/gtk20
 |Gtk+ 2 toolkit
 
 |`gtk30`
 |x11-toolkits/gtk30
 |Gtk+ 3 toolkit
 
 |`gtkmm20`
 |x11-toolkits/gtkmm20
 |c++ bindings 2.0 for the gtk20 toolkit
 
 |`gtkmm24`
 |x11-toolkits/gtkmm24
 |c++ bindings 2.4 for the gtk20 toolkit
 
 |`gtkmm30`
 |x11-toolkits/gtkmm30
 |c++ bindings 3.0 for the gtk30 toolkit
 
 |`gtksourceview2`
 |x11-toolkits/gtksourceview2
 |Widget that adds syntax highlighting to GtkTextView
 
 |`gtksourceview3`
 |x11-toolkits/gtksourceview3
 |Text widget that adds syntax highlighting to the GtkTextView widget
 
 |`gtksourceviewmm3`
 |x11-toolkits/gtksourceviewmm3
 |c++ bindings for the gtksourceview3 library
 
 |`gvfs`
 |devel/gvfs
 |GNOME virtual file system
 
 |`intltool`
 |textproc/intltool
 |Tool for internationalization (also see intlhack)
 
 |`introspection`
 |devel/gobject-introspection
 |Basic introspection bindings and tools to generate introspection bindings. Most of the time :build is enough, :both/:run is only need for applications that use introspection bindings. (both, build, run)
 
 |`libgda5`
 |databases/libgda5
 |Provides uniform access to different kinds of data sources
 
 |`libgda5-ui`
 |databases/libgda5-ui
 |UI library from the libgda5 library
 
 |`libgdamm5`
 |databases/libgdamm5
 |c++ bindings for the libgda5 library
 
 |`libgsf`
 |devel/libgsf
 |Extensible I/O abstraction for dealing with structured file formats
 
 |`librsvg2`
 |graphics/librsvg2
 |Library for parsing and rendering SVG vector-graphic files
 
 |`libsigc++20`
 |devel/libsigc++20
 |Callback Framework for C++
 
 |`libxml++26`
 |textproc/libxml++26
 |c++ bindings for the libxml2 library
 
 |`libxml2`
 |textproc/libxml2
 |XML parser library (both, build, run)
 
 |`libxslt`
 |textproc/libxslt
 |XSLT C library (both, build, run)
 
 |`metacity`
 |x11-wm/metacity
 |Window manager from GNOME
 
 |`nautilus3`
 |x11-fm/nautilus
 |GNOME file manager
 
 |`pango`
 |x11-toolkits/pango
 |Open-source framework for the layout and rendering of i18n text
 
 |`pangomm`
 |x11-toolkits/pangomm
 |c++ bindings for the pango library
 
 |`py3gobject3`
 |devel/py3-gobject3
 |Python 3, GObject 3.0 bindings
 
 |`pygobject3`
 |devel/py-gobject3
 |Python 2, GObject 3.0 bindings
 
 |`vte3`
 |x11-toolkits/vte3
 |Terminal widget with improved accessibility and I18N support
 |===
 
 [[gnome-components-macro]]
 .GNOME Macro Components
 [cols="1,1", options="header"]
 |===
 | Component
 | Description
 
 |`gnomeprefix`
 |Supply `configure` with some default locations.
 
 |`intlhack`
 |Same as intltool, but patches to make sure [.filename]#share/locale/# is used. Please only use when `intltool` alone is not enough.
 
 |`referencehack`
 |This macro is there to help splitting of the API or reference documentation into its own port.
 |===
 
 [[gnome-components-legacy]]
 .GNOME Legacy Components
 [cols="1,1,1", options="header"]
 |===
 | Component
 | Associated program
 | Description
 
 |`atspi`
 |accessibility/at-spi
 |Assistive Technology Service Provider Interface
 
 |`esound`
 |audio/esound
 |Enlightenment sound package
 
 |`gal2`
 |x11-toolkits/gal2
 |Collection of widgets taken from GNOME 2 gnumeric
 
 |`gconf2`
 |devel/gconf2
 |Configuration database system for GNOME 2
 
 |`gconfmm26`
 |devel/gconfmm26
 |c++ bindings for gconf2
 
 |`gdkpixbuf`
 |graphics/gdk-pixbuf
 |Graphics library for GTK+
 
 |`glib12`
 |devel/glib12
 |glib 1.2 core library
 
 |`gnomedocutils`
 |textproc/gnome-doc-utils
 |GNOME doc utils
 
 |`gnomemimedata`
 |misc/gnome-mime-data
 |MIME and Application database for GNOME 2
 
 |`gnomesharp20`
 |x11-toolkits/gnome-sharp20
 |GNOME 2 interfaces for the .NET runtime
 
 |`gnomespeech`
 |accessibility/gnome-speech
 |GNOME 2 text-to-speech API
 
 |`gnomevfs2`
 |devel/gnome-vfs
 |GNOME 2 Virtual File System
 
 |`gtk12`
 |x11-toolkits/gtk12
 |Gtk+ 1.2 toolkit
 
 |`gtkhtml3`
 |www/gtkhtml3
 |Lightweight HTML rendering/printing/editing engine
 
 |`gtkhtml4`
 |www/gtkhtml4
 |Lightweight HTML rendering/printing/editing engine
 
 |`gtksharp20`
 |x11-toolkits/gtk-sharp20
 |GTK+ and GNOME 2 interfaces for the .NET runtime
 
 |`gtksourceview`
 |x11-toolkits/gtksourceview
 |Widget that adds syntax highlighting to GtkTextView
 
 |`libartgpl2`
 |graphics/libart_lgpl
 |Library for high-performance 2D graphics
 
 |`libbonobo`
 |devel/libbonobo
 |Component and compound document system for GNOME 2
 
 |`libbonoboui`
 |x11-toolkits/libbonoboui
 |GUI frontend to the libbonobo component of GNOME 2
 
 |`libgda4`
 |databases/libgda4
 |Provides uniform access to different kinds of data sources
 
 |`libglade2`
 |devel/libglade2
 |GNOME 2 glade library
 
 |`libgnome`
 |x11/libgnome
 |Libraries for GNOME 2, a GNU desktop environment
 
 |`libgnomecanvas`
 |graphics/libgnomecanvas
 |Graphics library for GNOME 2
 
 |`libgnomekbd`
 |x11/libgnomekbd
 |GNOME 2 keyboard shared library
 
 |`libgnomeprint`
 |print/libgnomeprint
 |Gnome 2 print support library
 
 |`libgnomeprintui`
 |x11-toolkits/libgnomeprintui
 |Gnome 2 print support library
 
 |`libgnomeui`
 |x11-toolkits/libgnomeui
 |Libraries for the GNOME 2 GUI, a GNU desktop environment
 
 |`libgtkhtml`
 |www/libgtkhtml
 |Lightweight HTML rendering/printing/editing engine
 
 |`libgtksourceviewmm`
 |x11-toolkits/libgtksourceviewmm
 |c++ binding of GtkSourceView
 
 |`libidl`
 |devel/libIDL
 |Library for creating trees of CORBA IDL file
 
 |`libsigc++12`
 |devel/libsigc++12
 |Callback Framework for C++
 
 |`libwnck`
 |x11-toolkits/libwnck
 |Library used for writing pagers and taskslists
 
 |`libwnck3`
 |x11-toolkits/libwnck3
 |Library used for writing pagers and taskslists
 
 |`orbit2`
 |devel/ORBit2
 |High-performance CORBA ORB with support for the C language
 
 |`pygnome2`
 |x11-toolkits/py-gnome2
 |Python bindings for GNOME 2
 
 |`pygobject`
 |devel/py-gobject
 |Python 2, GObject 2.0 bindings
 
 |`pygtk2`
 |x11-toolkits/py-gtk2
 |Set of Python bindings for GTK+
 
 |`pygtksourceview`
 |x11-toolkits/py-gtksourceview
 |Python bindings for GtkSourceView 2
 
 |`vte`
 |x11-toolkits/vte
 |Terminal widget with improved accessibility and I18N support
 |===
 
 [[gnome-components-deprecated]]
 .Deprecated Components: Do Not Use
 [cols="1,1", options="header"]
 |===
 | Component
 | Description
 
 |`pangox-compat`
 |pangox-compat has been deprecated and split off from the pango package.
 |===
 
 [[using-qt]]
 == Using Qt
 
 [NOTE]
 ====
 For ports that are part of Qt itself, see crossref:uses[uses-qt-dist,`qt-dist`].
 ====
 
 [[qt-common]]
 === Ports That Require Qt
 
 The Ports Collection provides support for Qt 5 with `USES+=qt:5`. Set `USE_QT` to the list of required Qt components (libraries, tools, plugins).
 
 The Qt framework exports a number of variables which can be used by ports, some of them listed below:
 
 [[using-qt-variables]]
 .Variables Provided to Ports That Use Qt
 [cols="1,1", frame="none"]
 |===
 |`QMAKE`
 |Full path to `qmake` binary.
 
 |`LRELEASE`
 |Full path to `lrelease` utility.
 
 |`MOC`
 |Full path to `moc`.
 
 |`RCC`
 |Full path to `rcc`.
 
 |`UIC`
 |Full path to `uic`.
 
 |`QT_INCDIR`
 |Qt include directory.
 
 |`QT_LIBDIR`
 |Qt libraries path.
 
 |`QT_PLUGINDIR`
 |Qt plugins path.
 |===
 
 [[qt-components]]
 === Component Selection
 
 Individual Qt tool and library dependencies must be specified in `USE_QT`. Every component can be suffixed with `_build` or `_run`, the suffix indicating whether the dependency on the component is at buildtime or runtime. If unsuffixed, the component will be depended on at both build- and runtime. Usually, library components are specified unsuffixed, tool components are mostly specified with the `_build` suffix and plugin components are specified with the `_run` suffix. The most commonly used components are listed below (all available components are listed in `_USE_QT_ALL`, and `_USE_QT5_ONLY` in [.filename]#/usr/ports/Mk/Uses/qt.mk#):
 [[using-qt-library-list]]
 .Available Qt Library Components
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`3d`
 |Qt3D module
 
 |`assistant`
 |Qt 5 documentation browser
 
 |`canvas3d`
 |Qt canvas3d module
 
 |`charts`
 |Qt 5 charts module
 
 |`concurrent`
 |Qt multi-threading module
 
 |`connectivity`
 |Qt connectivity (Bluetooth/NFC) module
 
 |`core`
 |Qt core non-graphical module
 
 |`datavis3d`
 |Qt 5 3D data visualization module
 
 |`dbus`
 |Qt D-Bus inter-process communication module
 
 |`declarative`
 |Qt declarative framework for dynamic user interfaces
 
 |`designer`
 |Qt 5 graphical user interface designer
 
 |`diag`
 |Tool for reporting diagnostic information about Qt and its environment
 
 |`doc`
 |Qt 5 documentation
 
 |`examples`
 |Qt 5 examples sourcecode
 
 |`gamepad`
 |Qt 5 Gamepad Module
 
 |`graphicaleffects`
 |Qt Quick graphical effects
 
 |`gui`
 |Qt graphical user interface module
 
 |`help`
 |Qt online help integration module
 
 |`l10n`
 |Qt localized messages
 
 |`linguist`
 |Qt 5 translation tool
 
 |`location`
 |Qt location module
 
 |`multimedia`
 |Qt audio, video, radio and camera support module
 
 |`network`
 |Qt network module
 
 |`networkauth`
 |Qt network auth module
 
 |`opengl`
 |Qt 5-compatible OpenGL support module
 
 |`paths`
 |Command line client to QStandardPaths
 
 |`phonon4`
 |KDE multimedia framework
 
 |`pixeltool`
 |Qt 5 screen magnifier
 
 |`plugininfo`
 |Qt5 plugin metadata dumper
 
 |`printsupport`
 |Qt print support module
 
 |`qdbus`
 |Qt command-line interface to D-Bus
 
 |`qdbusviewer`
 |Qt 5 graphical interface to D-Bus
 
 |`qdoc`
 |Qt documentation generator
 
 |`qdoc-data`
 |QDoc configuration files
 
 |`qev`
 |Qt QWidget events introspection tool
 
 |`qmake`
 |Qt Makefile generator
 
 |`quickcontrols`
 |Set of controls for building complete interfaces in Qt Quick
 
 |`quickcontrols2`
 |Set of controls for building complete interfaces in Qt Quick
 
 |`remoteobjects`
 |Qt5 SXCML module
 
 |`script`
 |Qt 4-compatible scripting module
 
 |`scripttools`
 |Qt Script additional components
 
 |`scxml`
 |Qt5 SXCML module
 
 |`sensors`
 |Qt sensors module
 
 |`serialbus`
 |Qt functions to access industrial bus systems
 
 |`serialport`
 |Qt functions to access serial ports
 
 |`speech`
 |Accessibilty features for Qt5
 
 |`sql`
 |Qt SQL database integration module
 
 |`sql-ibase`
 |Qt InterBase/Firebird database plugin
 
 |`sql-mysql`
 |Qt MySQL database plugin
 
 |`sql-odbc`
 |Qt Open Database Connectivity plugin
 
 |`sql-pgsql`
 |Qt PostgreSQL database plugin
 
 |`sql-sqlite2`
 |Qt SQLite 2 database plugin
 
 |`sql-sqlite3`
 |Qt SQLite 3 database plugin
 
 |`sql-tds`
 |Qt TDS Database Connectivity database plugin
 
 |`svg`
 |Qt SVG support module
 
 |`testlib`
 |Qt unit testing module
 
 |`uiplugin`
 |Custom Qt widget plugin interface for Qt Designer
 
 |`uitools`
 |Qt Designer UI forms support module
 
 |`virtualkeyboard`
 |Qt 5 Virtual Keyboard Module
 
 |`wayland`
 |Qt5 wrapper for Wayland
 
 |`webchannel`
 |Qt 5 library for integration of C++/QML with HTML/js clients
 
 |`webengine`
 |Qt 5 library to render web content
 
 |`webkit`
 |QtWebKit with a more modern WebKit code base
 
 |`websockets`
 |Qt implementation of WebSocket protocol
 
 |`websockets-qml`
 |Qt implementation of WebSocket protocol (QML bindings)
 
 |`webview`
 |Qt component for displaying web content
 
 |`widgets`
 |Qt C++ widgets module
 
 |`x11extras`
 |Qt platform-specific features for X11-based systems
 
 |`xml`
 |Qt SAX and DOM implementations
 
 |`xmlpatterns`
 |Qt support for XPath, XQuery, XSLT and XML Schema
 |===
 
 To determine the libraries an application depends on, run `ldd` on the main executable after a successful compilation.
 
 [[using-qt-tools-list]]
 .Available Qt Tool Components
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`buildtools`
 |build tools (`moc`, `rcc`), needed for almost every Qt application.
 
 |`linguisttools`
 |localization tools: `lrelease`, `lupdate`
 
 |`qmake`
 |Makefile generator/build utility
 |===
 
 [[using-qt-plugins-list]]
 .Available Qt Plugin Components
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`imageformats`
 |plugins for TGA, TIFF, and MNG image formats
 |===
 
 [[qt5-components-example]]
 .Selecting Qt 5 Components
 [example]
 ====
 In this example, the ported application uses the Qt 5 graphical user interface library, the Qt 5 core library, all of the Qt 5 code generation tools and Qt 5's Makefile generator. Since the `gui` library implies a dependency on the core library, `core` does not need to be specified. The Qt 5 code generation tools `moc`, `uic` and `rcc`, as well as the Makefile generator `qmake` are only needed at buildtime, thus they are specified with the `_build` suffix:
 
 [.programlisting]
 ....
 USES=	qt:5
 USE_QT=	gui buildtools_build qmake_build
 ....
 
 ====
 
 [[using-qmake]]
 === Using `qmake`
 
 If the application provides a qmake project file ([.filename]#*.pro#), define `USES= qmake` along with `USE_QT`. `USES= qmake` already implies a build dependency on qmake, therefore the qmake component can be omitted from `USE_QT`. Similar to <<using-cmake,CMake>>, qmake supports out-of-source builds, which can be enabled by specifying the `outsource` argument (see <<using-qmake-example,`USES= qmake` example>>). Also see <<using-qmake-arguments>>.
 [[using-qmake-arguments]]
 .Possible Arguments for `USES= qmake`
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 
 |`no_configure`
 |Do not add the configure target. This is implied by `HAS_CONFIGURE=yes` and `GNU_CONFIGURE=yes`. It is required when the build only needs the environment setup from `USES= qmake`, but otherwise runs `qmake` on its own.
 
 |`no_env`
 |Suppress modification of the configure and make environments. It is only required when `qmake` is used to configure the software and the build fails to understand the environment setup by `USES= qmake`.
 
 |`norecursive`
 |Do not pass the `-recursive` argument to `qmake`.
 
 |`outsource`
 |Perform an out-of-source build.
 |===
 
 [[using-qmake-variables]]
 .Variables for Ports That Use `qmake`
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 
 |`QMAKE_ARGS`
 |Port specific qmake flags to be passed to the `qmake` binary.
 
 |`QMAKE_ENV`
 |Environment variables to be set for the `qmake` binary. The default is `${CONFIGURE_ENV}`.
 
 |`QMAKE_SOURCE_PATH`
 |Path to qmake project files ([.filename]#.pro#). The default is `${WRKSRC}` if an out-of-source build is requested, empty otherwise.
 |===
 
 When using `USES= qmake`, these settings are deployed:
 
 [.programlisting]
 ....
 CONFIGURE_ARGS+=	--with-qt-includes=${QT_INCDIR} \
 			--with-qt-libraries=${QT_LIBDIR} \
 			--with-extra-libs=${LOCALBASE}/lib \
 			--with-extra-includes=${LOCALBASE}/include
 
 CONFIGURE_ENV+=	QTDIR="${QT_PREFIX}" QMAKE="${QMAKE}" \
 		MOC="${MOC}" RCC="${RCC}" UIC="${UIC}" \
 		QMAKESPEC="${QMAKESPEC}"
 
 PLIST_SUB+=	QT_INCDIR=${QT_INCDIR_REL} \
 		QT_LIBDIR=${QT_LIBDIR_REL} \
 		QT_PLUGINDIR=${QT_PLUGINDIR_REL}
 ....
 
 Some configure scripts do not support the arguments above. To suppress modification of `CONFIGURE_ENV` and `CONFIGURE_ARGS`, set `USES= qmake:no_env`.
 
 [[using-qmake-example]]
 .`USES= qmake` Example
 [example]
 ====
 This snippet demonstrates the use of qmake for a Qt 5 port:
 
 [.programlisting]
 ....
 USES=	qmake:outsource qt:5
 USE_QT=	buildtools_build
 ....
 
 ====
 
 Qt applications are often written to be cross-platform and often X11/Unix is not the platform they are developed on, which in turn leads to certain loose ends, like:
 
 * _Missing additional include paths._ Many applications come with system tray icon support, but neglect to look for includes and/or libraries in the X11 directories. To add directories to `qmake`'s include and library search paths via the command line, use:
 +
 [.programlisting]
 ....
 QMAKE_ARGS+=	INCLUDEPATH+=${LOCALBASE}/include \
 		LIBS+=-L${LOCALBASE}/lib
 ....
 
 * _Bogus installation paths._ Sometimes data such as icons or .desktop files are by default installed into directories which are not scanned by XDG-compatible applications. package:editors/texmaker[] is an example for this - look at [.filename]#patch-texmaker.pro# in the [.filename]#files# directory of that port for a template on how to remedy this directly in the `qmake` project file.
 
 
 [[using-kde]]
 == Using KDE
 
 [[kde5-variables]]
 === KDE Variable Definitions
 
 If the application depends on KDE, set `USES+=kde:5` and `USE_KDE` to the list of required components. `_build` and `_run` suffixes can be used to force components dependency type (for example, `baseapps_run`). If no suffix is set, a default dependency type will be used. To force both types, add the component twice with both suffixes (for example, `ecm_build ecm_run`). Available components are listed below (up-to-date components are also listed in [.filename]#/usr/ports/Mk/Uses/kde.mk#):
 [[using-kde-components]]
 .Available KDE Components
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`activities`
 |KF5 runtime and library to organize work in separate activities
 
 |`activities-stats`
 |KF5 statistics for activities
 
 |`activitymanagerd`
 |System service to manage user's activities, track the usage patterns
 
 |`akonadi`
 |Storage server for KDE-Pim
 
 |`akonadicalendar`
 |Akonadi Calendar Integration
 
 |`akonadiconsole`
 |Akonadi management and debugging console
 
 |`akonadicontacts`
 |Libraries and daemons to implement Contact Management in Akonadi
 
 |`akonadiimportwizard`
 |Import data from other mail clients to KMail
 
 |`akonadimime`
 |Libraries and daemons to implement basic email handling
 
 |`akonadinotes`
 |KDE library for accessing mail storages in MBox format
 
 |`akonadisearch`
 |Libraries and daemons to implement searching in Akonadi
 
 |`akregator`
 |A Feed Reader by KDE
 
 |`alarmcalendar`
 |KDE API for KAlarm alarms
 
 |`apidox`
 |KF5 API Documentation Tools
 
 |`archive`
 |KF5 library that provides classes for handling archive formats
 
 |`attica`
 |Open Collaboration Services API library KDE5 version
 
 |`attica5`
 |Open Collaboration Services API library KDE5 version
 
 |`auth`
 |KF5 abstraction to system policy and authentication features
 
 |`baloo`
 |KF5 Framework for searching and managing user metadata
 
 |`baloo-widgets`
 |BalooWidgets library
 
 |`baloo5`
 |KF5 Framework for searching and managing user metadata
 
 |`blog`
 |KDE API for weblogging access
 
 |`bookmarks`
 |KF5 library for bookmarks and the XBEL format
 
 |`breeze`
 |Plasma5 artwork, styles and assets for the Breeze visual style
 
 |`breeze-gtk`
 |Plasma5 Breeze visual style for Gtk
 
 |`breeze-icons`
 |Breeze icon theme for KDE
 
 |`calendarcore`
 |KDE calendar access library
 
 |`calendarsupport`
 |Calendar support libraries for KDEPim
 
 |`calendarutils`
 |KDE utility and user interface functions for accessing calendar
 
 |`codecs`
 |KF5 library for string manipulation
 
 |`completion`
 |KF5 text completion helpers and widgets
 
 |`config`
 |KF5 widgets for configuration dialogs
 
 |`configwidgets`
 |KF5 widgets for configuration dialogs
 
 |`contacts`
 |KDE api to manage contact information
 
 |`coreaddons`
 |KF5 addons to QtCore
 
 |`crash`
 |KF5 library to handle crash analysis and bug report from apps
 
 |`dbusaddons`
 |KF5 addons to QtDBus
 
 |`decoration`
 |Plasma5 library to create window decorations
 
 |`designerplugin`
 |KF5 integration of Frameworks widgets in Qt Designer/Creator
 
 |`discover`
 |Plasma5 package management tools
 
 |`dnssd`
 |KF5 abstraction to system DNSSD features
 
 |`doctools`
 |KF5 documentation generation from docbook
 
 |`drkonqi`
 |Plasma5 crash handler
 
 |`ecm`
 |Extra modules and scripts for CMake
 
 |`emoticons`
 |KF5 library to convert emoticons
 
 |`eventviews`
 |Event view libriares for KDEPim
 
 |`filemetadata`
 |KF5 library for extracting file metadata
 
 |`frameworkintegration`
 |KF5 workspace and cross-framework integration plugins
 
 |`gapi`
 |KDE based library to access google services
 
 |`globalaccel`
 |KF5 library to add support for global workspace shortcuts
 
 |`grantlee-editor`
 |Editor for Grantlee themes
 
 |`grantleetheme`
 |KDE PIM grantleetheme
 
 |`gravatar`
 |Library for gravatar support
 
 |`guiaddons`
 |KF5 addons to QtGui
 
 |`holidays`
 |KDE library for calendar holidays
 
 |`hotkeys`
 |Plasma5 library for hotkeys
 
 |`i18n`
 |KF5 advanced internationalization framework
 
 |`iconthemes`
 |KF5 library for handling icons in applications
 
 |`identitymanagement`
 |KDE pim identities
 
 |`idletime`
 |KF5 library for monitoring user activity
 
 |`imap`
 |KDE API for IMAP support
 
 |`incidenceeditor`
 |Incidence editor libriares for KDEPim
 
 |`infocenter`
 |Plasma5 utility providing system information
 
 |`init`
 |KF5 process launcher to speed up launching KDE applications
 
 |`itemmodels`
 |KF5 models for Qt Model/View system
 
 |`itemviews`
 |KF5 widget addons for Qt Model/View
 
 |`jobwidgets`
 |KF5 widgets for tracking KJob instance
 
 |`js`
 |KF5 library providing an ECMAScript interpreter
 
 |`jsembed`
 |KF5 library for binding JavaScript objects to QObjects
 
 |`kaddressbook`
 |KDE contact manager
 
 |`kalarm`
 |Personal alarm scheduler
 
 |`kalarm`
 |Personal alarm scheduler
 
 |`kate`
 |Basic editor framework for the KDE system
 
 |`kcmutils`
 |KF5 utilities for working with KCModules
 
 |`kde-cli-tools`
 |Plasma5 non-interactive system tools
 
 |`kde-gtk-config`
 |Plasma5 GTK2 and GTK3 configurator
 
 |`kdeclarative`
 |KF5 library providing integration of QML and KDE Frameworks
 
 |`kded`
 |KF5 extensible daemon for providing system level services
 
 |`kdelibs4support`
 |KF5 porting aid from KDELibs4
 
 |`kdepim-addons`
 |KDE PIM addons
 
 |`kdepim-apps-libs`
 |KDE PIM mail related libraries
 
 |`kdepim-runtime5`
 |KDE PIM tools and services
 
 |`kdeplasma-addons`
 |Plasma5 addons to improve the Plasma experience
 
 |`kdesu`
 |KF5 integration with su for elevated privileges
 
 |`kdewebkit`
 |KF5 library providing integration of QtWebKit
 
 |`kgamma5`
 |Plasma5 monitor's gamma settings
 
 |`khtml`
 |KF5 KTHML rendering engine
 
 |`kimageformats`
 |KF5 library providing support for additional image formats
 
 |`kio`
 |KF5 resource and network access abstraction
 
 |`kirigami2`
 |QtQuick based components set
 
 |`kitinerary`
 |Data Model and Extraction System for Travel Reservation information
 
 |`kmail`
 |KDE mail client
 
 |`kmail`
 |KDE mail client
 
 |`kmail-account-wizard`
 |KDE mail account wizard
 
 |`kmenuedit`
 |Plasma5 menu editor
 
 |`knotes`
 |Popup notes
 
 |`kontact`
 |KDE Personal Information Manager
 
 |`kontact`
 |KDE Personal Information Manager
 
 |`kontactinterface`
 |KDE glue for embedding KParts into Kontact
 
 |`korganizer`
 |Calendar and scheduling Program
 
 |`kpimdav`
 |A DAV protocol implementation with KJobs
 
 |`kpkpass`
 |Library to deal with Apple Wallet pass files
 
 |`kross`
 |KF5 multi-language application scripting
 
 |`kscreen`
 |Plasma5 screen management library
 
 |`kscreenlocker`
 |Plasma5 secure lock screen architecture
 
 |`ksmtp`
 |Job-based library to send email through an SMTP server
 
 |`ksshaskpass`
 |Plasma5 ssh-add frontend
 
 |`ksysguard`
 |Plasma5 utility to track and control the running processes
 
 |`kwallet-pam`
 |Plasma5 KWallet PAM Integration
 
 |`kwayland-integration`
 |Integration plugins for a Wayland-based desktop
 
 |`kwin`
 |Plasma5 window manager
 
 |`kwrited`
 |Plasma5 daemon listening for wall and write messages
 
 |`ldap`
 |LDAP access API for KDE
 
 |`libkcddb`
 |KDE CDDB library
 
 |`libkcompactdisc`
 |KDE library for interfacing with audio CDs
 
 |`libkdcraw`
 |LibRaw interface for KDE
 
 |`libkdegames`
 |Libraries used by KDE games
 
 |`libkdepim`
 |KDE PIM Libraries
 
 |`libkeduvocdocument`
 |Library for reading and writing vocabulary files
 
 |`libkexiv2`
 |Exiv2 library interface for KDE
 
 |`libkipi`
 |KDE Image Plugin Interface
 
 |`libkleo`
 |Certificate manager for KDE
 
 |`libksane`
 |SANE library interface for KDE
 
 |`libkscreen`
 |Plasma5 screen management library
 
 |`libksieve`
 |Sieve libriares for KDEPim
 
 |`libksysguard`
 |Plasma5 library to track and control running processes
 
 |`mailcommon`
 |Common libriares for KDEPim
 
 |`mailimporter`
 |Import mbox files to KMail
 
 |`mailtransport`
 |KDE library to managing mail transport
 
 |`marble`
 |Virtual globe and world atlas for KDE
 
 |`mbox`
 |KDE library for accessing mail storages in MBox format
 
 |`mbox-importer`
 |Import mbox files to KMail
 
 |`mediaplayer`
 |KF5 plugin interface for media player features
 
 |`messagelib`
 |Library for handling messages
 
 |`milou`
 |Plasma5 Plasmoid for search
 
 |`mime`
 |Library for handling MIME data
 
 |`newstuff`
 |KF5 library for downloading application assets from the network
 
 |`notifications`
 |KF5 abstraction for system notifications
 
 |`notifyconfig`
 |KF5 configuration system for KNotify
 
 |`okular`
 |KDE universal document viewer
 
 |`oxygen`
 |Plasma5 Oxygen style
 
 |`oxygen-icons5`
 |The Oxygen icon theme for KDE
 
 |`package`
 |KF5 library to load and install packages
 
 |`parts`
 |KF5 document centric plugin system
 
 |`people`
 |KF5 library providing access to contacts
 
 |`pim-data-exporter`
 |Import and export KDE PIM settings
 
 |`pimcommon`
 |Common libriares for KDEPim
 
 |`pimtextedit`
 |KDE library for PIM-specific text editing utilities
 
 |`plasma-browser-integration`
 |Plasma5 components to integrate browsers into the desktop
 
 |`plasma-desktop`
 |Plasma5 plasma desktop
 
 |`plasma-framework`
 |KF5 plugin based UI runtime used to write user interfaces
 
 |`plasma-integration`
 |Qt Platform Theme integration plugins for the Plasma workspaces
 
 |`plasma-pa`
 |Plasma5 Plasma pulse audio mixer
 
 |`plasma-sdk`
 |Plasma5 applications useful for Plasma development
 
 |`plasma-workspace`
 |Plasma5 Plasma workspace
 
 |`plasma-workspace-wallpapers`
 |Plasma5 wallpapers
 
 |`plotting`
 |KF5 lightweight plotting framework
 
 |`polkit-kde-agent-1`
 |Plasma5 daemon providing a polkit authentication UI
 
 |`powerdevil`
 |Plasma5 tool to manage the power consumption settings
 
 |`prison`
 |API to produce barcodes
 
 |`pty`
 |KF5 pty abstraction
 
 |`purpose`
 |Offers available actions for a specific purpose
 
 |`qqc2-desktop-style`
 |Qt QuickControl2 style for KDE
 
 |`runner`
 |KF5 parallelized query system
 
 |`service`
 |KF5 advanced plugin and service introspection
 
 |`solid`
 |KF5 hardware integration and detection
 
 |`sonnet`
 |KF5 plugin-based spell checking library
 
 |`syndication`
 |KDE RSS feed handling library
 
 |`syntaxhighlighting`
 |KF5 syntax highlighting engine for structured text and code
 
 |`systemsettings`
 |Plasma5 system settings
 
 |`texteditor`
 |KF5 advanced embeddable text editor
 
 |`textwidgets`
 |KF5 advanced text editing widgets
 
 |`threadweaver`
 |KF5 addons to QtDBus
 
 |`tnef`
 |KDE API for the handling of TNEF data
 
 |`unitconversion`
 |KF5 library for unit conversion
 
 |`user-manager`
 |Plasma5 user manager
 
 |`wallet`
 |KF5 secure and unified container for user passwords
 
 |`wayland`
 |KF5 Client and Server library wrapper for the Wayland libraries
 
 |`widgetsaddons`
 |KF5 addons to QtWidgets
 
 |`windowsystem`
 |KF5 library for access to the windowing system
 
 |`xmlgui`
 |KF5 user configurable main windows
 
 |`xmlrpcclient`
 |KF5 interaction with XMLRPC services
 |===
 
 [[kde5-components-example]]
 .`USE_KDE` Example
 [example]
 ====
 This is a simple example for a KDE port. `USES= cmake` instructs the port to utilize CMake, a configuration tool widely used by KDE projects (see <<using-cmake>> for detailed usage). `USE_KDE` brings dependency on KDE libraries. Required KDE components and other dependencies can be determined through the configure log. `USE_KDE` does not imply `USE_QT`. If a port requires some Qt components, specify them in `USE_QT`.
 
 [.programlisting]
 ....
 USES=		cmake kde:5 qt:5
 USE_KDE=	ecm
 USE_QT=		core buildtools_build qmake_build
 ....
 
 ====
 
 [[using-lxqt]]
 == Using LXQt
 
 Applications depending on LXQt should set `USES+= lxqt` and set `USE_LXQT` to the list of required components from the table below
 
 [[using-lxqt-components]]
 .Available LXQt Components
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`buildtools`
 |Helpers for additional CMake modules
 
 |`libfmqt`
 |Libfm Qt bindings
 
 |`lxqt`
 |LXQt core library
 
 |`qtxdg`
 |Qt implementation of freedesktop.org XDG specifications
 |===
 
 [[lxqt-components-example]]
 .`USE_LXQT` Example
 [example]
 ====
 This is a simple example, `USE_LXQT` adds a dependency on LXQt libraries. Required LXQt components and other dependencies can be determined from the configure log.
 
 [.programlisting]
 ....
 USES=	cmake lxqt qt:5 tar:xz
 USE_QT=		core dbus widgets buildtools_build qmake_build
 USE_LXQT=	buildtools libfmqt
 ....
 
 ====
 
 [[using-java]]
 == Using Java
 
 [[java-variables]]
 === Variable Definitions
 
 If the port needs a Java(TM) Development Kit (JDK(TM)) to either build, run or even extract the distfile, then define `USE_JAVA`.
 
 There are several JDKs in the ports collection, from various vendors, and in several versions. If the port must use a particular version, specify it using the `JAVA_VERSION` variable. The most current version is package:java/openjdk16[], with package:java/openjdk15[], package:java/openjdk14[], package:java/openjdk13[], package:java/openjdk12[], package:java/openjdk11[], package:java/openjdk8[], and package:java/openjdk7[] also available.
 [[using-java-variables]]
 .Variables Which May be Set by Ports That Use Java
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Means
 
 |`USE_JAVA`
 |Define for the remaining variables to have any effect.
 
 |`JAVA_VERSION`
 |List of space-separated suitable Java versions for the port. An optional `"+"` allows specifying a range of versions (allowed values: `7[+] 8[+] 11[+] 12[+] 13[+] 14[+] 15[+] 16[+]`).
 
 |`JAVA_OS`
 |List of space-separated suitable JDK port operating systems for the port (allowed values: `native linux`).
 
 |`JAVA_VENDOR`
 |List of space-separated suitable JDK port vendors for the port (allowed values: `openjdk oracle`).
 
 |`JAVA_BUILD`
 |When set, add the selected JDK port to the build dependencies.
 
 |`JAVA_RUN`
 |When set, add the selected JDK port to the run dependencies.
 
 |`JAVA_EXTRACT`
 |When set, add the selected JDK port to the extract dependencies.
 |===
 
 Below is the list of all settings a port will receive after setting `USE_JAVA`:
 
 [[using-java-variables2]]
 .Variables Provided to Ports That Use Java
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Value
 
 |`JAVA_PORT`
 |The name of the JDK port (for example, `java/openjdk6`).
 
 |`JAVA_PORT_VERSION`
 |The full version of the JDK port (for example, `1.6.0`). Only the first two digits of this version number are needed, use `${JAVA_PORT_VERSION:C/^([0-9])\.([0-9])(.*)$/\1.\2/}`.
 
 |`JAVA_PORT_OS`
 |The operating system used by the JDK port (for example, `'native'`).
 
 |`JAVA_PORT_VENDOR`
 |The vendor of the JDK port (for example, `'openjdk'`).
 
 |`JAVA_PORT_OS_DESCRIPTION`
 |Description of the operating system used by the JDK port (for example, `'Native'`).
 
 |`JAVA_PORT_VENDOR_DESCRIPTION`
 |Description of the vendor of the JDK port (for example, `'OpenJDK BSD Porting Team'`).
 
 |`JAVA_HOME`
 |Path to the installation directory of the JDK (for example, [.filename]#'/usr/local/openjdk6'#).
 
 |`JAVAC`
 |Path to the Java compiler to use (for example, [.filename]#'/usr/local/openjdk6/bin/javac'#).
 
 |`JAR`
 |Path to the `jar` tool to use (for example, [.filename]#'/usr/local/openjdk6/bin/jar'# or [.filename]#'/usr/local/bin/fastjar'#).
 
 |`APPLETVIEWER`
 |Path to the `appletviewer` utility (for example, [.filename]#'/usr/local/openjdk6/bin/appletviewer'#).
 
 |`JAVA`
 |Path to the `java` executable. Use this for executing Java programs (for example, [.filename]#'/usr/local/openjdk6/bin/java'#).
 
 |`JAVADOC`
 |Path to the `javadoc` utility program.
 
 |`JAVAH`
 |Path to the `javah` program.
 
 |`JAVAP`
 |Path to the `javap` program.
 
 |`JAVA_KEYTOOL`
 |Path to the `keytool` utility program.
 
 |`JAVA_N2A`
 |Path to the `native2ascii` tool.
 
 |`JAVA_POLICYTOOL`
 |Path to the `policytool` program.
 
 |`JAVA_SERIALVER`
 |Path to the `serialver` utility program.
 
 |`RMIC`
 |Path to the RMI stub/skeleton generator, `rmic`.
 
 |`RMIREGISTRY`
 |Path to the RMI registry program, `rmiregistry`.
 
 |`RMID`
 |Path to the RMI daemon program `rmid`.
 
 |`JAVA_CLASSES`
 |Path to the archive that contains the JDK class files, [.filename]#${JAVA_HOME}/jre/lib/rt.jar#.
 |===
 
 Use the `java-debug` make target to get information for debugging the port. It will display the value of many of the previously listed variables.
 
 Additionally, these constants are defined so all Java ports may be installed in a consistent way:
 
 [[using-java-constants]]
 .Constants Defined for Ports That Use Java
 [cols="1,1", frame="none", options="header"]
 |===
 | Constant
 | Value
 
 |`JAVASHAREDIR`
 |The base directory for everything related to Java. Default: [.filename]#${PREFIX}/share/java#.
 
 |`JAVAJARDIR`
 |The directory where JAR files is installed. Default: [.filename]#${JAVASHAREDIR}/classes#.
 
 |`JAVALIBDIR`
 |The directory where JAR files installed by other ports are located. Default: [.filename]#${LOCALBASE}/share/java/classes#.
 |===
 
 The related entries are defined in both `PLIST_SUB` (documented in <<plist-sub>>) and `SUB_LIST`.
 
 [[java-building-with-ant]]
 === Building with Ant
 
 When the port is to be built using Apache Ant, it has to define `USE_ANT`. Ant is thus considered to be the sub-make command. When no `do-build` target is defined by the port, a default one will be set that runs Ant according to `MAKE_ENV`, `MAKE_ARGS` and `ALL_TARGET`. This is similar to the `USES= gmake` mechanism, which is documented in <<building>>.
 
 [[java-best-practices]]
 === Best Practices
 
 When porting a Java library, the port has to install the JAR file(s) in [.filename]#${JAVAJARDIR}#, and everything else under [.filename]#${JAVASHAREDIR}/${PORTNAME}# (except for the documentation, see below). To reduce the packing file size, reference the JAR file(s) directly in the [.filename]#Makefile#. Use this statement (where [.filename]#myport.jar# is the name of the JAR file installed as part of the port):
 
 [.programlisting]
 ....
 PLIST_FILES+=	${JAVAJARDIR}/myport.jar
 ....
 
 When porting a Java application, the port usually installs everything under a single directory (including its JAR dependencies). The use of [.filename]#${JAVASHAREDIR}/${PORTNAME}# is strongly encouraged in this regard. It is up the porter to decide whether the port installs the additional JAR dependencies under this directory or uses the already installed ones (from [.filename]#${JAVAJARDIR}#).
 
 When porting a Java(TM) application that requires an application server such as package:www/tomcat7[] to run the service, it is quite common for a vendor to distribute a [.filename]#.war#. A [.filename]#.war# is a Web application ARchive and is extracted when called by the application. Avoid adding a [.filename]#.war# to [.filename]#pkg-plist#. It is not considered best practice. An application server will expand war archive, but not clean it up properly if the port is removed. A more desirable way of working with this file is to extract the archive, then install the files, and lastly add these files to [.filename]#pkg-plist#.
 
 [.programlisting]
 ....
 TOMCATDIR=	${LOCALBASE}/apache-tomcat-7.0
 WEBAPPDIR=	myapplication
 
 post-extract:
 	@${MKDIR} ${WRKDIR}/${PORTDIRNAME}
 	@${TAR} xf ${WRKDIR}/myapplication.war -C ${WRKDIR}/${PORTDIRNAME}
 
 do-install:
 	cd ${WRKDIR} && \
 	${INSTALL} -d -o ${WWWOWN} -g ${WWWGRP} ${TOMCATDIR}/webapps/${PORTDIRNAME}
 	cd ${WRKDIR}/${PORTDIRNAME} && ${COPYTREE_SHARE} \* ${WEBAPPDIR}/${PORTDIRNAME}
 ....
 
 Regardless of the type of port (library or application), the additional documentation is installed in the crossref:makefiles[install-documentation,same location] as for any other port. The Javadoc tool is known to produce a different set of files depending on the version of the JDK that is used. For ports that do not enforce the use of a particular JDK, it is therefore a complex task to specify the packing list ([.filename]#pkg-plist#). This is one reason why porters are strongly encouraged to use `PORTDOCS`. Moreover, even if the set of files that will be generated by `javadoc` can be predicted, the size of the resulting [.filename]#pkg-plist# advocates for the use of `PORTDOCS`.
 
 The default value for `DATADIR` is [.filename]#${PREFIX}/share/${PORTNAME}#. It is a good idea to override `DATADIR` to [.filename]#${JAVASHAREDIR}/${PORTNAME}# for Java ports. Indeed, `DATADIR` is automatically added to `PLIST_SUB` (documented in crossref:plist[plist-sub,Changing pkg-plist Based on Make Variables]) so use `%%DATADIR%%` directly in [.filename]#pkg-plist#.
 
 As for the choice of building Java ports from source or directly installing them from a binary distribution, there is no defined policy at the time of writing. However, people from the https://www.freebsd.org/java/[FreeBSD Java Project] encourage porters to have their ports built from source whenever it is a trivial task.
 
 All the features that have been presented in this section are implemented in [.filename]#bsd.java.mk#. If the port needs more sophisticated Java support, please first have a look at the https://cgit.FreeBSD.org/ports/tree/Mk/bsd.java.mk[bsd.java.mk Git log] as it usually takes some time to document the latest features. Then, if the needed support that is lacking would be beneficial to many other Java ports, feel free to discuss it on the freebsd-java.
 
 Although there is a `java` category for PRs, it refers to the JDK porting effort from the FreeBSD Java project. Therefore, submit the Java port in the `ports` category as for any other port, unless the issue is related to either a JDK implementation or [.filename]#bsd.java.mk#.
 
 Similarly, there is a defined policy regarding the `CATEGORIES` of a Java port, which is detailed in crossref:makefiles[makefile-categories,Categorization].
 
 [[using-php]]
 == Web Applications, Apache and PHP
 
 [[using-apache]]
 === Apache
 
 [[using-apache-variables]]
 .Variables for Ports That Use Apache
 [cols="1,1", frame="none"]
 |===
 |`USE_APACHE`
 |The port requires Apache. Possible values: `yes` (gets any version), `22`, `24`, `22-24`, `22+`, etc. The default APACHE version is `22`. More details are available in [.filename]#ports/Mk/bsd.apache.mk# and at https://wiki.freebsd.org/Apache/[wiki.freebsd.org/Apache/].
 
 |`APXS`
 |Full path to the `apxs` binary. Can be overridden in the port.
 
 |`HTTPD`
 |Full path to the `httpd` binary. Can be overridden in the port.
 
 |`APACHE_VERSION`
 |The version of present Apache installation (read-only variable). This variable is only available after inclusion of [.filename]#bsd.port.pre.mk#. Possible values: `22`, `24`.
 
 |`APACHEMODDIR`
 |Directory for Apache modules. This variable is automatically expanded in [.filename]#pkg-plist#.
 
 |`APACHEINCLUDEDIR`
 |Directory for Apache headers. This variable is automatically expanded in [.filename]#pkg-plist#.
 
 |`APACHEETCDIR`
 |Directory for Apache configuration files. This variable is automatically expanded in [.filename]#pkg-plist#.
 |===
 
 [[using-apache-modules]]
 .Useful Variables for Porting Apache Modules
 [cols="1,1", frame="none"]
 |===
 |`MODULENAME`
 |Name of the module. Default value is `PORTNAME`. Example: `mod_hello`
 
 |`SHORTMODNAME`
 |Short name of the module. Automatically derived from `MODULENAME`, but can be overridden. Example: `hello`
 
 |`AP_FAST_BUILD`
 |Use `apxs` to compile and install the module.
 
 |`AP_GENPLIST`
 |Also automatically creates a [.filename]#pkg-plist#.
 
 |`AP_INC`
 |Adds a directory to a header search path during compilation.
 
 |`AP_LIB`
 |Adds a directory to a library search path during compilation.
 
 |`AP_EXTRAS`
 |Additional flags to pass to `apxs`.
 |===
 
 [[web-apps]]
 === Web Applications
 
 Web applications must be installed into [.filename]#PREFIX/www/appname#. This path is available both in [.filename]#Makefile# and in [.filename]#pkg-plist# as `WWWDIR`, and the path relative to `PREFIX` is available in [.filename]#Makefile# as `WWWDIR_REL`.
 
 The user and group of web server process are available as `WWWOWN` and `WWWGRP`, in case the ownership of some files needs to be changed. The default values of both are `www`. Use `WWWOWN?= myuser` and `WWWGRP?= mygroup` if the port needs different values. This allows the user to override them easily.
 
 [IMPORTANT]
 ====
 Use `WWWOWN` and `WWWGRP` sparingly. Remember that every file the web server can write to is a security risk waiting to happen.
 ====
 
 Do not depend on Apache unless the web app explicitly needs Apache. Respect that users may wish to run a web application on a web server other than Apache.
 
 [[php-variables]]
 === PHP
 
 PHP web applications declare their dependency on it with `USES=php`. See crossref:uses[uses-php,`php`] for more information.
 
 [[php-pear]]
 === PEAR Modules
 
 Porting PEAR modules is a very simple process.
 
 Add `USES=pear` to the port's [.filename]#Makefile#. The framework will install the relevant files in the right places and automatically generate the plist at install time.
 
 [[pear-makefile]]
 .Example Makefile for PEAR Class
 [example]
 ====
 [.programlisting]
 ....
 PORTNAME=       Date
 DISTVERSION=	1.4.3
 CATEGORIES=	devel www pear
 
 MAINTAINER=	example@domain.com
 COMMENT=	PEAR Date and Time Zone Classes
 
 USES=	pear
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 [TIP]
 ====
 PEAR modules will automatically be flavorized using crossref:flavors[flavors-auto-php,PHP flavors].
 ====
 
 [NOTE]
 ====
 If a non default `PEAR_CHANNEL` is used, the build and run-time dependencies will automatically be added.
 ====
 
 [IMPORTANT]
 ====
 PEAR modules do not need to defined `PKGNAMESUFFIX` it is automatically filled in using `PEAR_PKGNAMEPREFIX`. If a port needs to add to `PKGNAMEPREFIX`, it must also use `PEAR_PKGNAMEPREFIX` to differentiate between different flavors.
 ====
 
 [[php-horde]]
 ==== Horde Modules
 
 In the same way, porting Horde modules is a simple process.
 
 Add `USES=horde` to the port's [.filename]#Makefile#. The framework will install the relevant files in the right places and automatically generate the plist at install time.
 
 The `USE_HORDE_BUILD` and `USE_HORDE_RUN` variables can be used to add buildtime and runtime dependencies on other Horde modules. See [.filename]#Mk/Uses/horde.mk# for a complete list of available modules.
 
 [[horde-Makefile]]
 .Example Makefile for Horde Module
 [example]
 ====
 [.programlisting]
 ....
 PORTNAME=	Horde_Core
 DISTVERSION=	2.14.0
 CATEGORIES=	devel www pear
 
 MAINTAINER=	horde@FreeBSD.org
 COMMENT=	Horde Core Framework libraries
 
 OPTIONS_DEFINE=	KOLAB SOCKETS
 KOLAB_DESC=	Enable Kolab server support
 SOCKETS_DESC=	Depend on sockets PHP extension
 
 USES=	horde
 USE_PHP=	session
 
 USE_HORDE_BUILD=	Horde_Role
 USE_HORDE_RUN=	Horde_Role Horde_History Horde_Pack \
 		Horde_Text_Filter Horde_View
 
 KOLAB_USE=	HORDE_RUN=Horde_Kolab_Server,Horde_Kolab_Session
 SOCKETS_USE=	PHP=sockets
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 [TIP]
 ====
 As Horde modules are also PEAR modules they will also automatically be flavorized using crossref:flavors[flavors-auto-php,PHP flavors].
 ====
 
 [[using-python]]
 == Using Python
 
 The Ports Collection supports parallel installation of multiple Python versions. Ports must use a correct `python` interpreter, according to the user-settable `PYTHON_VERSION`. Most prominently, this means replacing the path to `python` executable in scripts with the value of `PYTHON_CMD`.
 
 Ports that install files under `PYTHON_SITELIBDIR` must use the `pyXY-` package name prefix, so their package name embeds the version of Python they are installed into.
 
 [.programlisting]
 ....
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 ....
 
 
 [[using-python-variables]]
 .Most Useful Variables for Ports That Use Python
 [cols="1,1", frame="none"]
 |===
 |`USES=python`
 |The port needs Python. The minimal required version can be specified with values such as `2.7+`. Version ranges can also be specified by separating two version numbers with a dash: `USES=python:3.2-3.3`
 
 |`USE_PYTHON=distutils`
 |Use Python distutils for configuring, compiling, and installing. This is required when the port comes with [.filename]#setup.py#. This overrides the `do-build` and `do-install` targets and may also override `do-configure` if `GNU_CONFIGURE` is not defined. Additionally, it implies `USE_PYTHON=flavors`.
 
 |`USE_PYTHON=autoplist`
 |Create the packaging list automatically. This also requires `USE_PYTHON=distutils` to be set.
 
 |`USE_PYTHON=concurrent`
 |The port will use an unique prefix, typically `PYTHON_PKGNAMEPREFIX` for certain directories, such as `EXAMPLESDIR` and `DOCSDIR` and also will append a suffix, the python version from `PYTHON_VER`, to binaries and scripts to be installed. This allows ports to be installed for different Python versions at the same time, which otherwise would install conflicting files.
 
 |`USE_PYTHON=flavors`
 |The port does not use distutils but still supports multiple Python versions. `FLAVORS` will be set to the supported Python versions. See crossref:flavors[flavors-auto-python,`USES`=python and Flavors]for more information.
 
 |`USE_PYTHON=optsuffix`
 |If the current Python version is not the default version, the port will gain `PKGNAMESUFFIX=${PYTHON_PKGNAMESUFFIX}`. Only useful with flavors.
 
 |`PYTHON_PKGNAMEPREFIX`
 |Used as a `PKGNAMEPREFIX` to distinguish packages for different Python versions. Example: `py27-`
 
 |`PYTHON_SITELIBDIR`
 |Location of the site-packages tree, that contains installation path of Python (usually `LOCALBASE`). `PYTHON_SITELIBDIR` can be very useful when installing Python modules.
 
 |`PYTHONPREFIX_SITELIBDIR`
 |The PREFIX-clean variant of PYTHON_SITELIBDIR. Always use `%%PYTHON_SITELIBDIR%%` in [.filename]#pkg-plist# when possible. The default value of `%%PYTHON_SITELIBDIR%%` is `lib/python%%PYTHON_VERSION%%/site-packages`
 
 |`PYTHON_CMD`
 |Python interpreter command line, including version number.
 |===
 
 [[using-python-variables-helpers]]
 .Python Module Dependency Helpers
 [cols="1,1", frame="none"]
 |===
 |`PYNUMERIC`
 |Dependency line for numeric extension.
 
 |`PYNUMPY`
 |Dependency line for the new numeric extension, numpy. (PYNUMERIC is deprecated by upstream vendor).
 
 |`PYXML`
 |Dependency line for XML extension (not needed for Python 2.0 and higher as it is also in base distribution).
 
 |`PY_ENUM34`
 |Conditional dependency on package:devel/py-enum34[] depending on the Python version.
 
 |`PY_ENUM_COMPAT`
 |Conditional dependency on package:devel/py-enum-compat[] depending on the Python version.
 
 |`PY_PATHLIB`
 |Conditional dependency on package:devel/py-pathlib[] depending on the Python version.
 
 |`PY_IPADDRESS`
 |Conditional dependency on package:net/py-ipaddress[] depending on the Python version.
 
 |`PY_FUTURES`
 |Conditional dependency on package:devel/py-futures[] depending on the Python version.
 |===
 
 A complete list of available variables can be found in [.filename]#/usr/ports/Mk/Uses/python.mk#.
 
 [IMPORTANT]
 ====
 All dependencies to Python ports using crossref:flavors[flavors-auto-python,Python flavors] (either with `USE_PYTHON=distutils` or `USE_PYTHON=flavors`) must have the Python flavor appended to their origin using `@${PY_FLAVOR}`. See <<python-Makefile>>.
 ====
 
 [[python-Makefile]]
 .Makefile for a Simple Python Module
 [example]
 ====
 [.programlisting]
 ....
 PORTNAME=	sample
 DISTVERSION=	1.2.3
 CATEGORIES=	devel
 
 MAINTAINER=	john@doe.tld
 COMMENT=	Python sample module
 
 RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}six>0:devel/py-six@${PY_FLAVOR}
 
 USES=		python
 USE_PYTHON=	autoplist distutils
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 Some Python applications claim to have `DESTDIR` support (which would be required for staging) but it is broken (Mailman up to 2.1.16, for instance). This can be worked around by recompiling the scripts. This can be done, for example, in the `post-build` target. Assuming the Python scripts are supposed to reside in `PYTHONPREFIX_SITELIBDIR` after installation, this solution can be applied:
 
 [.programlisting]
 ....
 (cd ${STAGEDIR}${PREFIX} \
   && ${PYTHON_CMD} ${PYTHON_LIBDIR}/compileall.py \
    -d ${PREFIX} -f ${PYTHONPREFIX_SITELIBDIR:S;${PREFIX}/;;})
 ....
 
 This recompiles the sources with a path relative to the stage directory, and prepends the value of `PREFIX` to the file name recorded in the byte-compiled output file by `-d`. `-f` is required to force recompilation, and the `:S;${PREFIX}/;;` strips prefixes from the value of `PYTHONPREFIX_SITELIBDIR` to make it relative to `PREFIX`.
 
 [[using-tcl]]
 == Using Tcl/Tk
 
 The Ports Collection supports parallel installation of multiple Tcl/Tk versions. Ports should try to support at least the default Tcl/Tk version and higher with `USES=tcl`. It is possible to specify the desired version of `tcl` by appending `:_xx_`, for example, `USES=tcl:85`.
 [[using-tcl-variables]]
 .The Most Useful Read-Only Variables for Ports That Use Tcl/Tk
 [cols="1,1", frame="none"]
 |===
 |`TCL_VER`
 | chosen major.minor version of Tcl
 
 |`TCLSH`
 | full path of the Tcl interpreter
 
 |`TCL_LIBDIR`
 | path of the Tcl libraries
 
 |`TCL_INCLUDEDIR`
 | path of the Tcl C header files
 
 |`TK_VER`
 | chosen major.minor version of Tk
 
 |`WISH`
 | full path of the Tk interpreter
 
 |`TK_LIBDIR`
 | path of the Tk libraries
 
 |`TK_INCLUDEDIR`
 | path of the Tk C header files
 |===
 
 See the crossref:uses[uses-tcl,`USES=tcl`] and crossref:uses[uses-tk,`USES=tk`] of crossref:uses[uses,Using `USES` Macros] for a full description of those variables. A complete list of those variables is available in [.filename]#/usr/ports/Mk/Uses/tcl.mk#.
 
 [[using-ruby]]
 == Using Ruby
 
 [[using-ruby-variables]]
 .Useful Variables for Ports That Use Ruby
 [cols="1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 
 |`USE_RUBY`
 |Adds build and run dependencies on Ruby.
 
 |`USE_RUBY_EXTCONF`
 |The port uses [.filename]#extconf.rb# to configure.
 
 |`USE_RUBY_SETUP`
 |The port uses [.filename]#setup.rb# to configure.
 
 |`RUBY_SETUP`
 |Override the name of the setup script from [.filename]#setup.rb#. Another common value is [.filename]#install.rb#.
 |===
 
 This table shows the selected variables available to port authors via the ports infrastructure. These variables are used to install files into their proper locations. Use them in [.filename]#pkg-plist# as much as possible. Do not redefine these variables in the port.
 [[using-ruby-variables-ro]]
 .Selected Read-Only Variables for Ports That Use Ruby
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 | Example value
 
 |`RUBY_PKGNAMEPREFIX`
 |Used as a `PKGNAMEPREFIX` to distinguish packages for different Ruby versions.
 |`ruby19-`
 
 |`RUBY_VERSION`
 |Full version of Ruby in the form of `x.y.z[.p]`.
 |`1.9.3.484`
 
 |`RUBY_SITELIBDIR`
 |Architecture independent libraries installation path.
 |`/usr/local/lib/ruby/site_ruby/1.9`
 
 |`RUBY_SITEARCHLIBDIR`
 |Architecture dependent libraries installation path.
 |`/usr/local/lib/ruby/site_ruby/1.9/amd64-freebsd10`
 
 |`RUBY_MODDOCDIR`
 |Module documentation installation path.
 |`/usr/local/share/doc/ruby19/patsy`
 
 |`RUBY_MODEXAMPLESDIR`
 |Module examples installation path.
 |`/usr/local/share/examples/ruby19/patsy`
 |===
 
 A complete list of available variables can be found in [.filename]#/usr/ports/Mk/bsd.ruby.mk#.
 
 [[using-sdl]]
 == Using SDL
 
 `USE_SDL` is used to autoconfigure the dependencies for ports which use an SDL based library like package:devel/sdl12[] and package:graphics/sdl_image[].
 
 These SDL libraries for version 1.2 are recognized:
 
 * sdl: package:devel/sdl12[]
 * console: package:devel/sdl_console[]
 * gfx: package:graphics/sdl_gfx[]
 * image: package:graphics/sdl_image[]
 * mixer: package:audio/sdl_mixer[]
 * mm: package:devel/sdlmm[]
 * net: package:net/sdl_net[]
 * pango: package:x11-toolkits/sdl_pango[]
 * sound: package:audio/sdl_sound[]
 * ttf: package:graphics/sdl_ttf[]
 
 These SDL libraries for version 2.0 are recognized:
 
 * sdl: package:devel/sdl20[]
 * gfx: package:graphics/sdl2_gfx[]
 * image: package:graphics/sdl2_image[]
 * mixer: package:audio/sdl2_mixer[]
 * net: package:net/sdl2_net[]
 * ttf: package:graphics/sdl2_ttf[]
 
 Therefore, if a port has a dependency on package:net/sdl_net[] and package:audio/sdl_mixer[], the syntax will be:
 
 [.programlisting]
 ....
 USE_SDL=	net mixer
 ....
 
 The dependency package:devel/sdl12[], which is required by package:net/sdl_net[] and package:audio/sdl_mixer[], is automatically added as well.
 
 Using `USE_SDL` with entries for SDL 1.2, it will automatically:
 
 * Add a dependency on sdl12-config to `BUILD_DEPENDS`
 * Add the variable `SDL_CONFIG` to `CONFIGURE_ENV`
 * Add the dependencies of the selected libraries to `LIB_DEPENDS`
 
 Using `USE_SDL` with entries for SDL 2.0, it will automatically:
 
 * Add a dependency on sdl2-config to `BUILD_DEPENDS`
 * Add the variable `SDL2_CONFIG` to `CONFIGURE_ENV`
 * Add the dependencies of the selected libraries to `LIB_DEPENDS`
 
 
 [[using-wx]]
 == Using wxWidgets
 
 This section describes the status of the wxWidgets libraries in the ports tree and its integration with the ports system.
 
 [[wx-introduction]]
 === Introduction
 
 There are many versions of the wxWidgets libraries which conflict between them (install files under the same name). In the ports tree this problem has been solved by installing each version under a different name using version number suffixes.
 
 The obvious disadvantage of this is that each application has to be modified to find the expected version. Fortunately, most of the applications call the `wx-config` script to determine the necessary compiler and linker flags. The script is named differently for every available version. Majority of applications respect an environment variable, or accept a configure argument, to specify which `wx-config` script to call. Otherwise they have to be patched.
 
 [[wx-version]]
 === Version Selection
 
 To make the port use a specific version of wxWidgets there are two variables available for defining (if only one is defined the other will be set to a default value):
 
 [[wx-ver-sel-table]]
 .Variables to Select wxWidgets Versions
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Variable
 | Description
 | Default value
 
 |`USE_WX`
 |List of versions the port can use
 |All available versions
 
 |`USE_WX_NOT`
 |List of versions the port cannot use
 |None
 |===
 
 The available wxWidgets versions and the corresponding ports in the tree are:
 
 [[wx-widgets-versions-table]]
 .Available wxWidgets Versions
 [cols="1,1", frame="none", options="header"]
 |===
 | Version
 | Port
 
 |`2.8`
 |package:x11-toolkits/wxgtk28[]
 
 |`3.0`
 |package:x11-toolkits/wxgtk30[]
 |===
 
 The variables in <<wx-ver-sel-table>> can be set to one or more of these combinations separated by spaces:
 
 [[wx-widgets-versions-specification]]
 .wxWidgets Version Specifications
 [cols="1,1", frame="none", options="header"]
 |===
 | Description
 | Example
 
 |Single version
 |`2.8`
 
 |Ascending range
 |`2.8+`
 
 |Descending range
 |`3.0-`
 
 |Full range (must be ascending)
 |`2.8-3.0`
 |===
 
 There are also some variables to select the preferred versions from the available ones. They can be set to a list of versions, the first ones will have higher priority.
 [[wx-widgets-preferred-version]]
 .Variables to Select Preferred wxWidgets Versions
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Designed for
 
 |`WANT_WX_VER`
 |the port
 
 |`WITH_WX_VER`
 |the user
 |===
 
 [[wx-components]]
 === Component Selection
 
 There are other applications that, while not being wxWidgets libraries, are related to them. These applications can be specified in `WX_COMPS`. These components are available:
 [[wx-widgets-components-table]]
 .Available wxWidgets Components
 [cols="1,1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 | Version restriction
 
 |`wx`
 |main library
 |none
 
 |`contrib`
 |contributed libraries
 |`none`
 
 |`python`
 |wxPython (Python bindings)
 |`2.8-3.0`
 |===
 
 The dependency type can be selected for each component by adding a suffix separated by a semicolon. If not present then a default type will be used (see <<wx-def-dep-types>>). These types are available:
 [[wx-widgets-dependency-table]]
 .Available wxWidgets Dependency Types
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`build`
 |Component is required for building, equivalent to `BUILD_DEPENDS`
 
 |`run`
 |Component is required for running, equivalent to `RUN_DEPENDS`
 
 |`lib`
 |Component is required for building and running, equivalent to `LIB_DEPENDS`
 |===
 
 The default values for the components are detailed in this table:
 
 [[wx-def-dep-types]]
 .Default wxWidgets Dependency Types
 [cols="1,1", frame="none", options="header"]
 |===
 | Component
 | Dependency type
 
 |`wx`
 |`lib`
 
 |`contrib`
 |`lib`
 
 |`python`
 |`run`
 
 |`mozilla`
 |`lib`
 
 |`svg`
 |`lib`
 |===
 
 [[wx-components-example]]
 .Selecting wxWidgets Components
 [example]
 ====
 This fragment corresponds to a port which uses wxWidgets version `2.4` and its contributed libraries.
 
 [.programlisting]
 ....
 USE_WX=		2.8
 WX_COMPS=	wx contrib
 ....
 
 ====
 
 [[wx-version-detection]]
 === Detecting Installed Versions
 
 To detect an installed version, define `WANT_WX`. If it is not set to a specific version then the components will have a version suffix. `HAVE_WX` will be filled after detection.
 
 [[wx-ver-det-example]]
 .Detecting Installed wxWidgets Versions and Components
 [example]
 ====
 This fragment can be used in a port that uses wxWidgets if it is installed, or an option is selected.
 
 [.programlisting]
 ....
 WANT_WX=	yes
 
 .include <bsd.port.pre.mk>
 
 .if defined(WITH_WX) || !empty(PORT_OPTIONS:MWX) || !empty(HAVE_WX:Mwx-2.8)
 USE_WX=			2.8
 CONFIGURE_ARGS+=	--enable-wx
 .endif
 ....
 
 This fragment can be used in a port that enables wxPython support if it is installed or if an option is selected, in addition to wxWidgets, both version `2.8`.
 
 [.programlisting]
 ....
 USE_WX=		2.8
 WX_COMPS=	wx
 WANT_WX=	2.8
 
 .include <bsd.port.pre.mk>
 
 .if defined(WITH_WXPYTHON) || !empty(PORT_OPTIONS:MWXPYTHON) || !empty(HAVE_WX:Mpython)
 WX_COMPS+=		python
 CONFIGURE_ARGS+=	--enable-wxpython
 .endif
 ....
 
 ====
 
 [[wx-defined-variables]]
 === Defined Variables
 
 These variables are available in the port (after defining one from <<wx-ver-sel-table>>).
 
 [[wx-widgets-variables]]
 .Variables Defined for Ports That Use wxWidgets
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`WX_CONFIG`
 |The path to the wxWidgets`wx-config` script (with different name)
 
 |`WXRC_CMD`
 |The path to the wxWidgets`wxrc` program (with different name)
 
 |`WX_VERSION`
 |The wxWidgets version that is going to be used (for example, `2.6`)
 |===
 
 [[wx-premk]]
 === Processing in [.filename]#bsd.port.pre.mk#
 
 Define `WX_PREMK` to be able to use the variables right after including [.filename]#bsd.port.pre.mk#.
 
 [IMPORTANT]
 ====
 When defining `WX_PREMK`, then the version, dependencies, components and defined variables will not change if modifying the wxWidgets port variables _after_ including [.filename]#bsd.port.pre.mk#.
 ====
 
 [[wx-premk-example]]
 .Using wxWidgets Variables in Commands
 [example]
 ====
 This fragment illustrates the use of `WX_PREMK` by running the `wx-config` script to obtain the full version string, assign it to a variable and pass it to the program.
 
 [.programlisting]
 ....
 USE_WX=		2.8
 WX_PREMK=	yes
 
 .include <bsd.port.pre.mk>
 
 .if exists(${WX_CONFIG})
 VER_STR!=	${WX_CONFIG} --release
 
 PLIST_SUB+=	VERSION="${VER_STR}"
 .endif
 ....
 
 ====
 
 [NOTE]
 ====
 The wxWidgets variables can be safely used in commands when they are inside targets without the need of `WX_PREMK`.
 ====
 
 [[wx-additional-config-args]]
 === Additional `configure` Arguments
 
 Some GNU `configure` scripts cannot find wxWidgets with just the `WX_CONFIG` environment variable set, requiring additional arguments. `WX_CONF_ARGS` can be used for provide them.
 [[wx-conf-args-values]]
 .Legal Values for `WX_CONF_ARGS`
 [cols="1,1", frame="none", options="header"]
 |===
 | Possible value
 | Resulting argument
 
 |`absolute`
 |`--with-wx-config=${WX_CONFIG}`
 
 |`relative`
 |`--with-wx=${LOCALBASE} --with-wx-config=${WX_CONFIG:T}`
 |===
 
 [[using-lua]]
 == Using Lua
 
 This section describes the status of the Lua libraries in the ports tree and its integration with the ports system.
 
 [[lua-introduction]]
 === Introduction
 
 There are many versions of the Lua libraries and corresponding interpreters, which conflict between them (install files under the same name). In the ports tree this problem has been solved by installing each version under a different name using version number suffixes.
 
 The obvious disadvantage of this is that each application has to be modified to find the expected version. But it can be solved by adding some additional flags to the compiler and linker.
 
 Applications that use Lua should normally build for just one version. However, loadable modules for Lua are built in a separate flavor for each Lua version that they support, and dependencies on such modules should specify the flavor using the `@${LUA_FLAVOR}` suffix on the port origin.
 
 [[lua-version]]
 === Version Selection
 
 A port using Lua should have a line of this form:
 
 [.programlisting]
 ....
 USES=	lua
 ....
 
 If a specific version of Lua, or range of versions, is needed, it can be specified as a parameter in the form `XY` (which may be used multiple times), `XY+`, `-XY`, or `XY-ZA`. The default version of Lua as set via `DEFAULT_VERSIONS` will be used if it falls in the requested range, otherwise the closest requested version to the default will be used. For example:
 
 [.programlisting]
 ....
 USES=	lua:52-53
 ....
 
 Note that no attempt is made to adjust the version selection based on the presence of any already-installed Lua version.
 
 [NOTE]
 ====
 The `XY+` form of version specification should not be used without careful consideration; the Lua API changes to some extent in every version, and configuration tools like CMake or Autoconf will often fail to work on future versions of Lua until updated to do so.
 ====
 
 [[lua-version-config]]
 === Configuration and Compiler flags
 
 Software that uses Lua may have been written to auto-detect the Lua version in use. In general ports should override this assumption, and force the use of the specific Lua version selected as described above. Depending on the software being ported, this might require any or all of: 
 
 * Using `LUA_VER` as part of a parameter to the software's configuration script via `CONFIGURE_ARGS` or `CONFIGURE_ENV` (or equivalent for other build systems); 
 * Adding `-I${LUA_INCDIR}`, `-L${LUA_LIBDIR}`, and `-llua-${LUA_VER}` to `CFLAGS`, `LDFLAGS`, `LIBS` respectively as appropriate; 
 * Patch the software's configuration or build files to select the correct version. 
 
 
 [[lua-version-flavors]]
 === Version Flavors
 
 A port which installs a Lua module (rather than an application that simply makes use of Lua) should build a separate flavor for each supported Lua version. This is done by adding the `module` parameter:
 
 [.programlisting]
 ....
 USES=	lua:module
 ....
 
 A version number or range of versions can be specified as well; use a comma to separate parameters.
 
 Since each flavor must have a different package name, the variable `LUA_PKGNAMEPREFIX` is provided which will be set to an appropriate value; the intended usage is:
 
 [.programlisting]
 ....
 PKGNAMEPREFIX=	${LUA_PKGNAMEPREFIX}
 ....
 
 Module ports should normally install files only to `LUA_MODLIBDIR`, `LUA_MODSHAREDIR`, `LUA_DOCSDIR`, and `LUA_EXAMPLESDIR`, all of which are set up to refer to version-specific subdirectories. Installing any other files must be done with care to avoid conflicts between versions.
 
 A port (other than a Lua module) which wishes to build a separate package for each Lua version should use the `flavors` parameter:
 
 [.programlisting]
 ....
 USES=	lua:flavors
 ....
 
 This operates the same way as the `module` parameter described above, but without the assumption that the package should be documented as a Lua module (so `LUA_DOCSDIR` and `LUA_EXAMPLESDIR` are not defined by default). However, the port may choose to define `LUA_DOCSUBDIR` as a suitable subdirectory name (usually the port's `PORTNAME` as long as this does not conflict with the `PORTNAME` of any module), in which case the framework will define both `LUA_DOCSDIR` and `LUA_EXAMPLESDIR`. 
 
 As with module ports, a flavored port should avoid installing files that would conflict between versions. Typically this is done by adding `LUA_VER_STR` as a suffix to program names (e.g. using crossref:uses[uses-uniquefiles,`uniquefiles`]), and otherwise using either `LUA_VER` or `LUA_VER_STR` as part of any other files or subdirectories used outside of `LUA_MODLIBDIR` and `LUA_MODSHAREDIR`. 
 
 [[lua-defined-variables]]
 === Defined Variables
 
 These variables are available in the port.
 
 [[using-lua-variables-ports]]
 .Variables Defined for Ports That Use Lua
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`LUA_VER`
 |The Lua version that is going to be used (for example, `5.1`)
 
 |`LUA_VER_STR`
 |The Lua version without the dots (for example, `51`)
 
 |`LUA_FLAVOR`
 |The flavor name corresponding to the selected Lua version, to be used for specifying dependencies
 
 |`LUA_BASE`
 |The prefix that should be used to locate Lua (and components) that are already installed
 
 |`LUA_PREFIX`
 |The prefix where Lua (and components) are to be installed by this port
 
 |`LUA_INCDIR`
 |The directory where Lua header files are installed
 
 |`LUA_LIBDIR`
 |The directory where Lua libraries are installed
 
 |`LUA_REFMODLIBDIR`
 |The directory where Lua module libraries ([.filename]#.so#) that are already installed are to be found
 
 |`LUA_REFMODSHAREDIR`
 |The directory where Lua modules ([.filename]#.lua#) that are already installed are to be found
 
 |`LUA_MODLIBDIR`
 |The directory where Lua module libraries ([.filename]#.so#) are to be installed by this port
 
 |`LUA_MODSHAREDIR`
 |The directory where Lua modules ([.filename]#.lua#) are to be installed by this port
 
 |`LUA_PKGNAMEPREFIX`
 |The package name prefix used by Lua modules
 
 |`LUA_CMD`
 |The name of the Lua interpreter (e.g. `lua53`)
 
 |`LUAC_CMD`
 |The name of the Lua compiler (e.g. `luac53`)
 |===
 
 These additional variables are available for ports that specified the `module` parameter:
 
 [[using-lua-variables-modules]]
 .Variables Defined for Lua Module Ports
 [cols="1,1", frame="none", options="header"]
 |===
 | Name
 | Description
 
 |`LUA_DOCSDIR`
 |the directory to which the module's documentation should be installed.
 
 |`LUA_EXAMPLESDIR`
 |the directory to which the module's example files should be installed.
 |===
 
 [[lua-examples]]
 === Examples
 
 [[lua-app-Makefile]]
 .Makefile for an application using Lua
 [example]
 ====
 This example shows how to reference a Lua module required at run time. Notice that the reference must specify a flavor.
 
 [.programlisting]
 ....
 PORTNAME=	sample
 DISTVERSION=	1.2.3
 CATEGORIES=	whatever
 
 MAINTAINER=	john@doe.tld
 COMMENT=	Sample
 
 RUN_DEPENDS=	${LUA_REFMODLIBDIR}/lpeg.so:devel/lua-lpeg@${LUA_FLAVOR}
 
 USES=		lua
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 [[lua-mod-Makefile]]
 .Makefile for a simple Lua module
 [example]
 ====
 [.programlisting]
 ....
 PORTNAME=	sample
 DISTVERSION=	1.2.3
 CATEGORIES=	whatever
 PKGNAMEPREFIX=	${LUA_PKGNAMEPREFIX}
 
 MAINTAINER=	john@doe.tld
 COMMENT=	Sample
 
 USES=		lua:module
 
 DOCSDIR=	${LUA_DOCSDIR}
 
 .include <bsd.port.mk>
 ....
 
 ====
 
 [[using-iconv]]
 == Using `iconv`
 
 FreeBSD has a native `iconv` in the operating system.
 
 For software that needs `iconv`, define `USES=iconv`.
 
 When a port defines `USES=iconv`, these variables will be available:
 
 [.informaltable]
 [cols="1,1,1,1", frame="none", options="header"]
 |===
 | Variable name
 | Purpose
 | Port iconv (when using WCHAR_T or //TRANSLIT extensions)
 | Base iconv
 
 
 |`ICONV_CMD`
 |Directory where the `iconv` binary resides
 |`${LOCALBASE}/bin/iconv`
 |[.filename]#/usr/bin/iconv#
 
 |`ICONV_LIB`
 |`ld` argument to link to [.filename]#libiconv# (if needed)
 |`-liconv`
 |(empty)
 
 |`ICONV_PREFIX`
 |Directory where the `iconv` implementation resides (useful for configure scripts)
 |`${LOCALBASE}`
 |[.filename]#/usr#
 
 |`ICONV_CONFIGURE_ARG`
 |Preconstructed configure argument for configure scripts
 |`--with-libiconv-prefix=${LOCALBASE}`
 |(empty)
 
 |`ICONV_CONFIGURE_BASE`
 |Preconstructed configure argument for configure scripts
 |`--with-libiconv=${LOCALBASE}`
 |(empty)
 |===
 
 These two examples automatically populate the variables with the correct value for systems using package:converters/libiconv[] or the native `iconv` respectively:
 
 [[iconv-simple-use]]
 .Simple `iconv` Usage
 [example]
 ====
 [.programlisting]
 ....
 USES=		iconv
 LDFLAGS+=	-L${LOCALBASE}/lib ${ICONV_LIB}
 ....
 
 ====
 
 [[iconv-configure-use]]
 .`iconv` Usage with `configure`
 [example]
 ====
 [.programlisting]
 ....
 USES=		iconv
 CONFIGURE_ARGS+=${ICONV_CONFIGURE_ARG}
 ....
 
 ====
 
 As shown above, `ICONV_LIB` is empty when a native `iconv` is present. This can be used to detect the native `iconv` and respond appropriately.
 
 Sometimes a program has an `ld` argument or search path hardcoded in a [.filename]#Makefile# or configure script. This approach can be used to solve that problem:
 
 [[iconv-reinplace]]
 .Fixing Hardcoded `-liconv`
 [example]
 ====
 [.programlisting]
 ....
 USES=		iconv
 
 post-patch:
 	@${REINPLACE_CMD} -e 's/-liconv/${ICONV_LIB}/' ${WRKSRC}/Makefile
 ....
 
 ====
 
 In some cases it is necessary to set alternate values or perform operations depending on whether there is a native `iconv`. [.filename]#bsd.port.pre.mk# must be included before testing the value of `ICONV_LIB`:
 
 [[iconv-conditional]]
 .Checking for Native `iconv` Availability
 [example]
 ====
 [.programlisting]
 ....
 USES=		iconv
 
 .include <bsd.port.pre.mk>
 
 post-patch:
 .if empty(ICONV_LIB)
 	# native iconv detected
 	@${REINPLACE_CMD} -e 's|iconv||' ${WRKSRC}/Config.sh
 .endif
 
 .include <bsd.port.post.mk>
 ....
 
 ====
 
 [[using-xfce]]
 == Using Xfce
 
 Ports that need Xfce libraries or applications set `USES=xfce`.
 
 Specific Xfce library and application dependencies are set with values assigned to `USE_XFCE`. They are defined in [.filename]#/usr/ports/Mk/Uses/xfce.mk#. The possible values are:
 
 .Values of `USE_XFCE`
 garcon::
 package:sysutils/garcon[]
 
 libexo::
 package:x11/libexo[]
 
 libgui::
 package:x11-toolkits/libxfce4gui[]
 
 libmenu::
 package:x11/libxfce4menu[]
 
 libutil::
 package:x11/libxfce4util[]
 
 panel::
 package:x11-wm/xfce4-panel[]
 
 thunar::
 package:x11-fm/thunar[]
 
 xfconf::
 package:x11/xfce4-conf[]
 
 
 [[use-xfce]]
 .`USES=xfce` Example
 [example]
 ====
 [.programlisting]
 ....
 USES=		xfce
 USE_XFCE=	libmenu
 ....
 
 ====
 
 [[use-xfce-gtk2]]
 .Using Xfce's Own GTK2 Widgets
 [example]
 ====
 In this example, the ported application uses the GTK2-specific widgets package:x11/libxfce4menu[] and package:x11/xfce4-conf[].
 
 [.programlisting]
 ....
 USES=		xfce:gtk2
 USE_XFCE=	libmenu xfconf
 ....
 
 ====
 
 [TIP]
 ====
 Xfce components included this way will automatically include any dependencies they need. It is no longer necessary to specify the entire list. If the port only needs package:x11-wm/xfce4-panel[], use:
 
 [.programlisting]
 ....
 USES=		xfce
 USE_XFCE=	panel
 ....
 
 There is no need to list the components package:x11-wm/xfce4-panel[] needs itself like this:
 
 [.programlisting]
 ....
 USES=		xfce
 USE_XFCE=	libexo libmenu libutil panel
 ....
 
 However, Xfce components and non-Xfce dependencies of the port must be included explicitly. Do not count on an Xfce component to provide a sub-dependency other than itself for the main port.
 ====
 
 
 [[using-databases]]
 == Using Databases
 
 Use one of the `USES` macros from <<using-databases-uses>> to add a dependency on a database.
 
 [[using-databases-uses]]
 .Database `USES` Macros
 [cols="1,1", frame="none", options="header"]
 |===
 | Database
 | USES Macro
 
 |Berkeley DB
 |crossref:uses[uses-bdb,`bdb`]
 
 |MariaDB, MySQL, Percona
 |crossref:uses[uses-mysql,`mysql`]
 
 |PostgreSQL
 |crossref:uses[uses-pgsql,`pgsql`]
 
 |SQLite
 |crossref:uses[uses-sqlite,`sqlite`]
 |===
 
 [[using-databases-bdb-ex1]]
 .Using Berkeley DB 6
 [example]
 ====
 [.programlisting]
 ....
 USES=	bdb:6
 ....
 
 See crossref:uses[uses-bdb,`bdb`] for more information.
 ====
 
 [[using-databases-mysql-ex1]]
 .Using MySQL
 [example]
 ====
 When a port needs the MySQL client library add
 
 [.programlisting]
 ....
 USES=	mysql
 ....
 
 See crossref:uses[uses-mysql,`mysql`] for more information.
 ====
 
 [[using-databases-pgsql-ex1]]
 .Using PostgreSQL
 [example]
 ====
 When a port needs the PostgreSQL server version 9.6 or later add
 
 [.programlisting]
 ....
 USES=		pgsql:9.6+
 WANT_PGSQL=	server
 ....
 
 See crossref:uses[uses-pgsql,`pgsql`] for more information.
 ====
 
 [[using-databases-sqlite-ex1]]
 .Using SQLite 3
 [example]
 ====
 [.programlisting]
 ....
 USES=	sqlite:3
 ....
 
 See crossref:uses[uses-sqlite,`sqlite`] for more information.
 ====
 
 [[rc-scripts]]
 == Starting and Stopping Services (`rc` Scripts)
 
 [.filename]#rc.d# scripts are used to start services on system startup, and to give administrators a standard way of stopping, starting and restarting the service. Ports integrate into the system [.filename]#rc.d# framework. Details on its usage can be found in link:{handbook}#configtuning-rcd/[the rc.d Handbook chapter]. Detailed explanation of the available commands is provided in man:rc[8] and man:rc.subr[8]. Finally, there is link:{rc-scripting}[an article] on practical aspects of [.filename]#rc.d# scripting.
 
 With a mythical port called _doorman_, which needs to start a _doormand_ daemon. Add the following to the [.filename]#Makefile#:
 
 [.programlisting]
 ....
 USE_RC_SUBR=	doormand
 ....
 
 Multiple scripts may be listed and will be installed. Scripts must be placed in the [.filename]#files# subdirectory and a `.in` suffix must be added to their filename. Standard `SUB_LIST` expansions will be ran against this file. Use of the `%%PREFIX%%` and `%%LOCALBASE%%` expansions is strongly encouraged as well. More on `SUB_LIST` in crossref:pkg-files[using-sub-files,the relevant section].
 
 As of FreeBSD 6.1-RELEASE, local [.filename]#rc.d# scripts (including those installed by ports) are included in the overall man:rcorder[8] of the base system.
 
 An example simple [.filename]#rc.d# script to start the doormand daemon:
 
 [.programlisting]
 ....
 #!/bin/sh
 
 # $FreeBSD$
 #
 # PROVIDE: doormand
 # REQUIRE: LOGIN
 # KEYWORD: shutdown
 #
 # Add these lines to /etc/rc.conf.local or /etc/rc.conf
 # to enable this service:
 #
 # doormand_enable (bool):	Set to NO by default.
 #				Set it to YES to enable doormand.
 # doormand_config (path):	Set to %%PREFIX%%/etc/doormand/doormand.cf
 #				by default.
 
 . /etc/rc.subr
 
 name=doormand
 rcvar=doormand_enable
 
 load_rc_config $name
 
 : ${doormand_enable:="NO"}
 : ${doormand_config="%%PREFIX%%/etc/doormand/doormand.cf"}
 
 command=%%PREFIX%%/sbin/${name}
 pidfile=/var/run/${name}.pid
 
 command_args="-p $pidfile -f $doormand_config"
 
 run_rc_command "$1"
 ....
 
 Unless there is a very good reason to start the service earlier, or it runs as a particular user (other than root), all ports scripts must use:
 
 [.programlisting]
 ....
 REQUIRE: LOGIN
 ....
 
 If the startup script launches a daemon that must be shutdown, the following will trigger a stop of the service on system shutdown:
 
 [.programlisting]
 ....
 KEYWORD: shutdown
 ....
 
 If the script is not starting a persistent service this is not necessary.
 
 For optional configuration elements the "=" style of default variable assignment is preferable to the ":=" style here, since the former sets a default value only if the variable is unset, and the latter sets one if the variable is unset _or_ null. A user might very well include something like:
 
 [.programlisting]
 ....
 doormand_flags=""
 ....
 
 in their [.filename]#rc.conf.local#, and a variable substitution using ":=" would inappropriately override the user's intention. The `_enable` variable is not optional, and must use the ":" for the default.
 
 [IMPORTANT]
 ====
 Ports _must not_ start and stop their services when installing and deinstalling. Do not abuse the [.filename]#plist# keywords described in crossref:plist[plist-keywords-base-exec, "the @preexec command,@postexec command,@preunexec command,@postunexec command section"] by running commands that modify the currently running system, including starting or stopping services.
 ====
 
 [[rc-scripts-checklist]]
 === Pre-Commit Checklist
 
 Before contributing a port with an [.filename]#rc.d# script, and more importantly, before committing one, please consult this checklist to be sure that it is ready.
 
 The package:devel/rclint[] port can check for most of these, but it is not a substitute for proper review.
 
 [.procedure]
 . If this is a new file, does it have a [.filename]#.sh# extension? If so, that must be changed to just [.filename]#file.in# since [.filename]#rc.d# files may not end with that extension.
 . Does the file have a `$FreeBSD$` tag?
 . Do the name of the file (minus [.filename]#.in#), the `PROVIDE` line, and `$` _name_ all match? The file name matching `PROVIDE` makes debugging easier, especially for man:rcorder[8] issues. Matching the file name and `$`_name_ makes it easier to figure out which variables are relevant in [.filename]#rc.conf[.local]#. It is also a policy for all new scripts, including those in the base system.
 . Is the `REQUIRE` line set to `LOGIN`? This is mandatory for scripts that run as a non-root user. If it runs as root, is there a good reason for it to run prior to `LOGIN`? If not, it must run after so that local scrips can be loosely grouped to a point in man:rcorder[8] after most everything in the base is already running.
 . Does the script start a persistent service? If so, it must have `KEYWORD: shutdown`.
 . Make sure there is no `KEYWORD: FreeBSD` present. This has not been necessary nor desirable for years. It is also an indication that the new script was copy/pasted from an old script, so extra caution must be given to the review.
 . If the script uses an interpreted language like `perl`, `python`, or `ruby`, make certain that `command_interpreter` is set appropriately, for example, for Perl, by adding `PERL=${PERL}` to `SUB_LIST` and using `%%PERL%%`. Otherwise,
 +
 [source,shell]
 ....
 # service name stop
 ....
-+ 
++
 will probably not work properly. See man:service[8] for more information.
 . Have all occurrences of [.filename]#/usr/local# been replaced with `%%PREFIX%%`?
 . Do the default variable assignments come after `load_rc_config`?
 . Are there default assignments to empty strings? They should be removed, but double-check that the option is documented in the comments at the top of the file.
 . Are things that are set in variables actually used in the script?
 . Are options listed in the default _name_`_flags` things that are actually mandatory? If so, they must be in `command_args`. `-d` is a red flag (pardon the pun) here, since it is usually the option to "daemonize" the process, and therefore is actually mandatory.
 . `_name__flags` must never be included in `command_args` (and vice versa, although that error is less common).
 . Does the script execute any code unconditionally? This is frowned on. Usually these things must be dealt with through a `start_precmd`.
 . All boolean tests must use the `checkyesno` function. No hand-rolled tests for `[Yy][Ee][Ss]`, etc.
 . If there is a loop (for example, waiting for something to start) does it have a counter to terminate the loop? We do not want the boot to be stuck forever if there is an error.
 . Does the script create files or directories that need specific permissions, for example, a [.filename]#pid# that needs to be owned by the user that runs the process? Rather than the traditional man:touch[1]/man:chown[8]/man:chmod[1] routine, consider using man:install[1] with the proper command line arguments to do the whole procedure with one step.
 
 [[users-and-groups]]
 == Adding Users and Groups
 
 Some ports require a particular user account to be present, usually for daemons that run as that user. For these ports, choose a _unique_ UID from 50 to 999 and register it in [.filename]#ports/UIDs# (for users) and [.filename]#ports/GIDs# (for groups). The unique identification should be the same for users and groups.
 
 Please include a patch against these two files when requiring a new user or group to be created for the port.
 
 Then use `USERS` and `GROUPS` in [.filename]#Makefile#, and the user will be automatically created when installing the port.
 
 [.programlisting]
 ....
 USERS=	pulse
 GROUPS=	pulse pulse-access pulse-rt
 ....
 
 The current list of reserved UIDs and GIDs can be found in [.filename]#ports/UIDs# and [.filename]#ports/GIDs#.
 
 [[requiring-kernel-sources]]
 == Ports That Rely on Kernel Sources
 
 Some ports (such as kernel loadable modules) need the kernel source files so that the port can compile. Here is the correct way to determine if the user has them installed:
 
 [.programlisting]
 ....
 USES=	kmod
 ....
 
 Apart from this check, the `kmod` feature takes care of most items that these ports need to take into account.
 
 [[go-libs]]
 == Go Libraries
 
 Ports must not package or install Go libs or source code. Go ports must fetch the required deps at the normal fetch time and should only install the programs and things users need, not the things Go developers would need.
 
 Ports should (in order of preference):
 
 * Use vendored dependencies included with the package source.
 * Fetch the versions of deps specified by upstream (in the case of go.mod, vendor.json or similar).
 * As a last resort (deps are not included nor versions specified exactly) fetch versions of dependencies available at the time of upstream development/release.
 
 
 [[haskell-libs]]
 == Haskell Libraries
 
 Just like in case of Go language, Ports must not package or install Haskell libraries. Haskell ports must link statically to their dependencies and fetch all distribution files on fetch stage.
 
 [[shell-completion]]
 == Shell Completion Files
 
 Many modern shells (including bash, fish, tcsh and zsh) support parameter and/or option tab-completion. This support usually comes from completion files, which contain the definitions for how tab completion will work for a certain command. Ports sometimes ship with their own completion files, or porters may have created them themselves.
 
 When available, completion files should always be installed. It is not necessary to make an option for it. If an option is used, though, always enable it in `OPTIONS_DEFAULT`.
 [[shell-completion-paths]]
 .Shell completion file paths
 [cols="1,1", frame="none"]
 |===
 |`bash`
 |[.filename]#${PREFIX}/etc/bash_completion.d#
 
 |`fish`
 |[.filename]#${PREFIX}/share/fish/vendor_completions.d#
 
 |`zsh`
 |[.filename]#${PREFIX}/share/zsh/site-functions#
 |===
 
 Do not register any dependencies on the shells themselves.