Index: head/en_US.ISO8859-1/books/handbook/bibliography/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/bibliography/chapter.xml (revision 49530) +++ head/en_US.ISO8859-1/books/handbook/bibliography/chapter.xml (revision 49531) @@ -1,603 +1,603 @@ Bibliography While manual pages provide a definitive reference for individual pieces of the &os; 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; system administration. Books Specific to &os; International books: Using FreeBSD (in Traditional Chinese), published by Drmaster, 1997. ISBN 9-578-39435-7. FreeBSD Unleashed (Simplified Chinese translation), published by 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 Posts & Telecom Press. ISBN 7-115-10541-3. FreeBSD & Windows (in Simplified Chinese), published by 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. Complete Introduction to FreeBSD (in Japanese), published by Shoeisha Co., Ltd. ISBN 4-88135-473-6 P3600E. Personal UNIX Starter Kit FreeBSD (in Japanese), published by ASCII. ISBN 4-7561-1733-3 P3000E. FreeBSD Handbook (Japanese translation), published by ASCII. ISBN 4-7561-1580-2 P3800E. FreeBSD mit Methode (in German), published by Computer und Literatur Verlag/Vertrieb Hanser, 1998. ISBN 3-932311-31-0. FreeBSD de Luxe (in German), published by Verlag Modere Industrie, 2003. ISBN 3-8266-1343-0. FreeBSD Install and Utilization Manual (in Japanese), published by Mainichi Communications Inc., 1998. ISBN 4-8399-0112-0. Onno W Purbo, Dodi Maryanto, Syahrial Hubbany, Widjil Widodo Building Internet Server with FreeBSD (in Indonesia Language), published by Elex Media Komputindo. Absolute BSD: The Ultimate Guide to FreeBSD (Traditional Chinese translation), published by GrandTech Press, 2003. ISBN 986-7944-92-5. The FreeBSD 6.0 Book (in Traditional Chinese), published by Drmaster, 2006. ISBN 9-575-27878-X. English language books: Absolute FreeBSD, 2nd Edition: The Complete Guide to FreeBSD, published by No Starch Press, 2007. ISBN: 978-1-59327-151-0 The Complete FreeBSD, published by O'Reilly, 2003. ISBN: 0596005164 The FreeBSD Corporate Networker's Guide, published by Addison-Wesley, 2000. ISBN: 0201704811 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 Sams, 2002. ISBN: 0672324245 FreeBSD 6 Unleashed, published by Sams, 2006. ISBN: 0672328755 FreeBSD: The Complete Reference, published by McGrawHill, - 2003. ISBN: 0072224096 + 2003. ISBN: 0072224096 Users' Guides Ohio State University has written a UNIX Introductory Course which is available online in HTML and PostScript format. An Italian translation of this document is available as part of the FreeBSD Italian Documentation Project. Jpman Project, Japan FreeBSD Users Group. FreeBSD User's Reference Manual (Japanese translation). Mainichi Communications Inc., 1998. ISBN4-8399-0088-4 P3800E. Edinburgh University has written an Online Guide for newcomers to the UNIX environment. Administrators' Guides Jpman Project, Japan FreeBSD Users Group. FreeBSD System Administrator's Manual (Japanese translation). Mainichi Communications Inc., 1998. ISBN4-8399-0109-0 P3300E. Dreyfus, Emmanuel. Cahiers de l'Admin: BSD 2nd Ed. (in French), Eyrolles, 2004. ISBN 2-212-11463-X 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. Code Reading: The Open Source Perspective. Addison-Wesley, 2003. ISBN 0-201-79940-5 Spinellis, Diomidis. 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 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 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 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 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 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 &unix; 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 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 online. Don Libes, Sandy Ressler Life with UNIX — special edition. Prentice-Hall, Inc., 1989. ISBN 0-13-536657-7 The BSD family tree. https://svnweb.freebsd.org/base/head/share/misc/bsd-family-tree?view=co or /usr/share/misc/bsd-family-tree on a FreeBSD machine. Networked Computer Science Technical Reports Library. http://www.ncstrl.org/ Old BSD releases from the Computer Systems Research group (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. Periodicals, Journals, and Magazines Admin Magazin (in German), published by Medialinx AG. ISSN: 2190-1066 BSD Magazine, published by Software Press Sp. z o.o. SK. ISSN: 1898-9144 BSD Now — Video Podcast, published by Jupiter Broadcasting LLC BSD Talk Podcast, by Will Backman FreeBSD Journal, published by S&W Publishing, sponsored by The FreeBSD Foundation. ISBN: 978-0-615-88479-0 Index: head/en_US.ISO8859-1/books/handbook/cutting-edge/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/cutting-edge/chapter.xml (revision 49530) +++ head/en_US.ISO8859-1/books/handbook/cutting-edge/chapter.xml (revision 49531) @@ -1,2205 +1,2205 @@ Updating and Upgrading &os; Jim Mock Restructured, reorganized, and parts updated by Jordan Hubbard Original work by Poul-Henning Kamp John Polstra Nik Clayton Synopsis &os; 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, &os; 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 &os; system up-to-date. After reading this chapter, you will know: How to keep a &os; system up-to-date with freebsd-update or Subversion. How to compare the state of an installed system against a known pristine copy. How to keep the installed documentation up-to-date with Subversion or documentation ports. The difference between the two development branches: &os.stable; and &os.current;. How to rebuild and reinstall the entire base system. Before reading this chapter, you should: Properly set up the network connection (). Know how to install additional third-party software (). Throughout this chapter, svn is used to obtain and update &os; sources. To use it, first install the devel/subversion port or package. &os; Update Tom Rhodes Written by Colin Percival Based on notes provided by Updating and Upgrading freebsd-update updating-upgrading Applying security patches in a timely manner and upgrading to a newer release of an operating system are important aspects of ongoing system administration. &os; includes a utility called freebsd-update which can be used to perform both these tasks. This utility supports binary security and errata updates to &os;, 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 http://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 http://www.FreeBSD.org/releases/. 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. The Configuration File The default configuration file for freebsd-update works as-is. Some users may wish to tweak the default configuration in /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: # Components of the base system which should be kept updated. Components world kernel This parameter controls which parts of &os; 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. # 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 /bin or /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. # 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. # When upgrading to a new &os; 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 /etc and just accept the merges. See for more information about mergemaster. # Directory in which to store downloaded updates and temporary # files used by &os; 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. # 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 &os; 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. Applying Security Patches The process of applying &os; security patches has been simplified, allowing an administrator to keep a system fully patched using freebsd-update. More information about &os; security advisories can be found in . &os; 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. &prompt.root; freebsd-update fetch &prompt.root; 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. The system can be configured to automatically check for updates once every day by adding this entry to /etc/crontab: @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: &prompt.root; 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 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. However, freebsd-update will detect and update the GENERIC kernel if /boot/GENERIC exists, even if it is not the current running kernel of the system. Always keep a copy of the GENERIC kernel in /boot/GENERIC. It will be helpful in diagnosing a variety of problems and in performing version upgrades. Refer to for instructions on how to get a copy of the GENERIC kernel. Unless the default configuration in /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 /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. Performing Major and Minor Version Upgrades Upgrades from one minor version of &os; to another, like from &os; 9.0 to &os; 9.1, are called minor version upgrades. Major version upgrades occur when &os; is upgraded from one major version to another, like from &os; 9.X to &os; 10.X. Both types of upgrades can be performed by providing freebsd-update with a release version target. If the system is running a custom kernel, make sure that a copy of the GENERIC kernel exists in /boot/GENERIC before starting the upgrade. Refer to for instructions on how to get a copy of the GENERIC kernel. The following command, when run on a &os; 9.0 system, will upgrade it to &os; 9.1: &prompt.root; 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: 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: 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 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 /etc and manually merge important files, such as master.passwd or group at a later time. 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: &prompt.root; 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 /boot/GENERIC: &prompt.root; nextboot -k GENERIC Before rebooting with the 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 GENERIC kernel using the /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: &prompt.root; 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. &prompt.root; freebsd-update install 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 . Custom Kernels with &os; 9.X and Later Before using freebsd-update, ensure that a copy of the GENERIC kernel exists in /boot/GENERIC. If a custom kernel has only been built once, the kernel in /boot/kernel.old is the GENERIC kernel. Simply rename this directory to /boot/kernel. 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: &prompt.root; mount /cdrom &prompt.root; cd /cdrom/usr/freebsd-dist &prompt.root; tar -C/ -xvf kernel.txz boot/kernel/kernel Alternately, the GENERIC kernel may be rebuilt and installed from source: &prompt.root; cd /usr/src &prompt.root; make kernel __MAKE_CONF=/dev/null SRCCONF=/dev/null For this kernel to be identified as the GENERIC kernel by freebsd-update, the 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 GENERIC kernel is not required as freebsd-update only needs /boot/GENERIC to exist. 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 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 &os;. The forced upgrade can be accomplished by performing: &prompt.root; pkg-static upgrade -f A rebuild of all installed applications can be accomplished with this command: &prompt.root; 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 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: &prompt.root; freebsd-update install If the GENERIC kernel was temporarily used, this is the time to build and install a new custom kernel using the instructions in . Reboot the machine into the new &os; version. The upgrade process is now complete. System State Comparison The state of the installed &os; 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). This command is not a replacement for a real IDS such as 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 To begin the comparison, specify the output file to save the results to: &prompt.root; 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: &prompt.root; 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, /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 /etc/freebsd-update.conf. Updating the Documentation Set Updating and Upgrading Documentation Updating and Upgrading Documentation is an integral part of the &os; operating system. While an up-to-date version of the &os; documentation is always available on the &os; web site (http://www.freebsd.org/doc/), it can be handy to have an up-to-date, local copy of the &os; website, handbooks, FAQ, and articles. This section describes how to use either source or the &os; Ports Collection to keep a local copy of the &os; documentation up-to-date. For information on editing and submitting corrections to the documentation, refer to the &os; Documentation Project Primer for New Contributors (http://www.freebsd.org/doc/en_US.ISO8859-1/books/fdp-primer/). Updating Documentation from Source Rebuilding the &os; documentation from source requires a collection of tools which are not part of the &os; base system. The required tools, including svn, can be installed from the textproc/docproj package or port developed by the &os; Documentation Project. Once installed, use svn to fetch a clean copy of the documentation source: &prompt.root; svn checkout https://svn.FreeBSD.org/doc/head /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: &prompt.root; svn update /usr/doc Once an up-to-date snapshot of the documentation sources has been fetched to /usr/doc, everything is ready for an update of the installed documentation. A full update of all available languages may be performed by typing: &prompt.root; cd /usr/doc &prompt.root; make install clean If an update of only a specific language is desired, make can be invoked in a language-specific subdirectory of /usr/doc: &prompt.root; cd /usr/doc/en_US.ISO8859-1 &prompt.root; make install clean An alternative way of updating the documentation is to run this command from /usr/doc or the desired language-specific subdirectory: &prompt.root; make update The output formats that will be installed may be specified by setting FORMATS: &prompt.root; cd /usr/doc &prompt.root; make FORMATS='html html-split' install clean Several options are available to ease the process of updating only parts of the documentation, or the build of specific translations. These options can be set either as system-wide options in /etc/make.conf, or as command-line options passed to make. The options include: DOC_LANG The list of languages and encodings to build and install, such as en_US.ISO8859-1 for English documentation. FORMATS A single format or a list of output formats to be built. Currently, html, html-split, txt, ps, and pdf are supported. DOCDIR Where to install the documentation. It defaults to /usr/share/doc. For more make variables supported as system-wide options in &os;, refer to &man.make.conf.5;. Updating Documentation from Ports Marc Fonvieille Based on the work of Updating and Upgrading documentation package Updating and Upgrading The previous section presented a method for updating the &os; documentation from sources. This section describes an alternative method which uses the Ports Collection and makes it possible to: Install pre-built packages of the documentation, without having to locally build anything or install the documentation toolchain. Build the documentation sources through the ports framework, making the checkout and build steps a bit easier. This method of updating the &os; documentation is supported by a set of documentation ports and packages which are updated by the &a.doceng; on a monthly basis. These are listed in the &os; Ports Collection, under the docs category (http://www.freshports.org/docs/). Organization of the documentation ports is as follows: The misc/freebsd-doc-en package or port installs all of the English documentation. The misc/freebsd-doc-all meta-package or port installs all documentation in all available languages. There is a package and port for each translation, such as misc/freebsd-doc-hu for the Hungarian documentation. When binary packages are used, the &os; documentation will be installed in all available formats for the given language. For example, the following command will install the latest package of the Hungarian documentation: &prompt.root; pkg install hu-freebsd-doc Packages use a format that differs from the corresponding port's name: lang-freebsd-doc, where lang is the short format of the language code, such as hu for Hungarian, or zh_cn for Simplified Chinese. To specify the format of the documentation, build the port instead of installing the package. For example, to build and install the English documentation: &prompt.root; cd /usr/ports/misc/freebsd-doc-en &prompt.root; make install clean The port provides a configuration menu where the format to build and install can be specified. By default, split HTML, similar to the format used on http://www.FreeBSD.org, and PDF are selected. Alternately, several make options can be specified when building a documentation port, including: WITH_HTML Builds the HTML format with a single HTML file per document. The formatted documentation is saved to a file called article.html, or book.html. WITH_PDF The formatted documentation is saved to a file called article.pdf or book.pdf. DOCBASE Specifies where to install the documentation. It defaults to /usr/local/share/doc/freebsd. This example uses variables to install the Hungarian documentation as a PDF in the specified directory: &prompt.root; cd /usr/ports/misc/freebsd-doc-hu &prompt.root; make -DWITH_PDF DOCBASE=share/doc/freebsd/hu install clean Documentation packages or ports can be updated using the instructions in . For example, the following command updates the installed Hungarian documentation using ports-mgmt/portmaster by using packages only: &prompt.root; portmaster -PP hu-freebsd-doc Tracking a Development Branch -CURRENT -STABLE &os; has two development branches: &os.current; and &os.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. Using &os.current; &os.current; is the bleeding edge of &os; development and &os.current; users are expected to have a high degree of technical skill. Less technical users who wish to track a development branch should track &os.stable; instead. &os.current; is the very latest source code for &os; and includes works in progress, experimental changes, and transitional mechanisms that might or might not be present in the next official release. While many &os; developers compile the &os.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 &os.current; brings disaster or new functionality can be a matter of when the source code was synced. &os.current; is made available for three primary interest groups: Members of the &os; community who are actively working on some part of the source tree. Members of the &os; community who are active testers. They are willing to spend time solving problems, making topical suggestions on changes and the general direction of &os;, 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. &os.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. &os.current; is not in any way officially supported. -CURRENT using To track &os.current;: Join the &a.current.name; and the &a.svn-src-head.name; 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 &os.current;. The &a.svn-src-head.name; 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 &a.mailman.lists.link;, 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 &os.current;, subscribe to the &a.svn-src-all.name; list. Synchronize with the &os.current; sources. Typically, svn is used to check out the -CURRENT code from the head branch of one of the Subversion mirror sites listed in . - Due to the size of the repository, some users choose + 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 &os.current;, not just selected portions. Before compiling &os.current; -CURRENT compiling , read /usr/src/Makefile very carefully and follow the instructions in . Read the &a.current; and /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! &os.current; users are encouraged to submit their suggestions for enhancements or bug fixes. Suggestions with accompanying code are always welcome. Using &os.stable; &os.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 &os.current;. This is still a development branch and, at any given time, the sources for &os.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 &os;. Those interested in tracking or contributing to the &os; development process, especially as it relates to the next release of &os;, should consider following &os.stable;. While the &os.stable; branch should compile and run at all times, this cannot be guaranteed. Since more people run &os.stable; than &os.current;, it is inevitable that bugs and corner cases will sometimes be found in &os.stable; that were not apparent in &os.current;. For this reason, one should not blindly track &os.stable;. It is particularly important not to update any production servers to &os.stable; without thoroughly testing the code in a development or testing environment. To track &os.stable;: -STABLE using Join the &a.stable.name; list in order to stay informed of build dependencies that may appear in &os.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 svn list for the branch being tracked. For example, users tracking the 9-STABLE branch should join the &a.svn-src-stable-9.name; list. 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 &a.mailman.lists.link;, click on the list to subscribe to, and follow the instructions. In order to track changes for the whole source tree, subscribe to &a.svn-src-all.name;. To install a new &os.stable; system, install the most recent &os.stable; release from the &os; mirror sites or use a monthly snapshot built from &os.stable;. Refer to www.freebsd.org/snapshots for more information about snapshots. To compile or upgrade to an existing &os; system to &os.stable;, use svn Subversion to check out the source for the desired branch. Branch names, such as stable/9, are listed at www.freebsd.org/releng. Before compiling or upgrading to &os.stable; -STABLE compiling , read /usr/src/Makefile carefully and follow the instructions in . Read &a.stable; and /usr/src/UPDATING to keep up-to-date on other bootstrapping procedures that sometimes become necessary on the road to the next release. Synchronizing Source There are various methods for staying up-to-date with the &os; sources. This section describes the primary service, Subversion. While it is possible to update only parts of the source tree, the only supported update procedure is to update the entire tree and recompile all the programs that run in user space, such as those in /bin and /sbin, and kernel sources. Updating only part of the source tree, only the kernel, or only the userland programs will often result in problems ranging from compile errors to kernel panics or data corruption. Subversion Subversion uses the pull model of updating sources. The user, or a cron script, invokes the svn program which updates the local version of the source. Subversion is the preferred method for updating local source trees as updates are up-to-the-minute and the user controls when updates are downloaded. It is easy to restrict updates to specific files or directories and the requested updates are generated on the fly by the server. How to synchronize source using Subversion is described in . If a user inadvertently wipes out portions of the local archive, Subversion will detect and rebuild the damaged portions during an update. Rebuilding World Rebuilding world Once the local source tree is synchronized against a particular version of &os; such as &os.stable; or &os.current;, the source tree can be used to rebuild the system. This process is known as rebuilding world. Before rebuilding world, be sure to perform the following tasks: Perform These Tasks <emphasis>Before</emphasis> Building World Backup all important data to another system or removable media, verify the integrity of the backup, and have a bootable installation media at hand. It cannot be stressed enough how important it is to make a backup of the system before rebuilding the system. While rebuilding world is an easy task, there will inevitably be times when mistakes in the source tree render the system unbootable. You will probably never have to use the backup, but it is better to be safe than sorry! mailing list Review the recent &a.stable.name; or &a.current.name; entries, depending upon the branch being tracked. Be aware of any known problems and which systems are affected. If a known issue affects the version of synchronized code, wait for an all clear announcement to be posted stating that the problem has been solved. Resynchronize the sources to ensure that the local version of source has the needed fix. Read /usr/src/UPDATING for any extra steps necessary for that version of the source. This file contains important information about potential problems and may specify the order to run certain commands. Many upgrades require specific additional steps such as renaming or deleting specific files prior to installing the new world. These will be listed at the end of this file where the currently recommended upgrade sequence is explicitly spelled out. If UPDATING contradicts any steps in this chapter, the instructions in UPDATING take precedence and should be followed. Do Not Use <command>make world</command> Some older documentation recommends using make world. However, that command skips some important steps and should only be used by experts. For almost all circumstances make world is the wrong thing to do, and the procedure described here should be used instead. Overview of Process The build world process assumes an upgrade from an older &os; version using the source of a newer version that was obtained using the instructions in . In &os;, the term world includes the kernel, core system binaries, libraries, programming files, and built-in compiler. The order in which these components are built and installed is important. For example, the old compiler might have a bug and not be able to compile the new kernel. Since the new kernel should be built with the new compiler, the new compiler must be built, but not necessarily installed, before the new kernel is built. The new world might rely on new kernel features, so the new kernel must be installed before the new world is installed. The old world might not run correctly on the new kernel, so the new world must be installed immediately upon installing the new kernel. Some configuration changes must be made before the new world is installed, but others might break the old world. Hence, two different configuration upgrade steps are used. For the most part, the update process only replaces or adds files and existing old files are not deleted. Since this can cause problems, /usr/src/UPDATING will indicate if any files need to be manually deleted and at which step to do so. These concerns have led to the recommended upgrade sequence described in the following procedure. It is a good idea to save the output from running make to a file. If something goes wrong, a copy of the error message can be posted to one of the &os; mailing lists. The easiest way to do this is to use script with a parameter that specifies the name of the file to save all output to. Do not save the output to /tmp as this directory may be cleared at next reboot. A better place to save the file is /var/tmp. Run this command immediately before rebuilding the world, and then type exit when the process has finished: &prompt.root; script /var/tmp/mw.out Script started, output file is /var/tmp/mw.out Overview of Build World Process The commands used in the build world process should be run in the order specified here. This section summarizes the function of each command. If the build world process has previously been run on this system, a copy of the previous build may still exist in /usr/obj. To speed up the new build world process, and possibly save some dependency headaches, remove this directory if it already exists: &prompt.root; chflags -R noschg /usr/obj/* &prompt.root; rm -rf /usr/obj Compile the new compiler and a few related tools, then use the new compiler to compile the rest of the new world. The result is saved to /usr/obj. &prompt.root; cd /usr/src &prompt.root; make buildworld Use the new compiler residing in /usr/obj to build the new kernel, in order to protect against compiler-kernel mismatches. This is necessary, as certain memory structures may have changed, and programs like ps and top will fail to work if the kernel and source code versions are not the same. &prompt.root; make buildkernel Install the new kernel and kernel modules, making it possible to boot with the newly updated kernel. If kern.securelevel has been raised above 1 and noschg or similar flags have been set on the kernel binary, drop the system into single-user mode first. Otherwise, this command can be run from multi-user mode without problems. See &man.init.8; for details about kern.securelevel and &man.chflags.1; for details about the various file flags. &prompt.root; make installkernel Drop the system into single-user mode in order to minimize problems from updating any binaries that are already running. It also minimizes any problems from running the old world on a new kernel. &prompt.root; shutdown now Once in single-user mode, run these commands if the system is formatted with UFS: &prompt.root; mount -u / &prompt.root; mount -a -t ufs &prompt.root; swapon -a If the system is instead formatted with ZFS, run these two commands. This example assumes a zpool name of zroot: &prompt.root; zfs set readonly=off zroot &prompt.root; zfs mount -a Optional: If a keyboard mapping other than the default US English is desired, it can be changed with &man.kbdmap.1;: &prompt.root; kbdmap Then, for either file system, if the CMOS clock is set to local time (this is true if the output of &man.date.1; does not show the correct time and zone), run: &prompt.root; adjkerntz -i Remaking the world will not update certain directories, such as /etc, /var and /usr, with new or changed configuration files. The next step is to perform some initial configuration file updates to /etc in preparation for the new world. The following command compares only those files that are essential for the success of installworld. For instance, this step may add new groups, system accounts, or startup scripts which have been added to &os; since the last update. This is necessary so that the installworld step will be able to use any new system accounts, groups, and scripts. Refer to for more detailed instructions about this command: &prompt.root; mergemaster -p Install the new world and system binaries from /usr/obj. &prompt.root; cd /usr/src &prompt.root; make installworld Update any remaining configuration files. &prompt.root; mergemaster -iF Delete any obsolete files. This is important as they may cause problems if left on the disk. &prompt.root; make delete-old A full reboot is now needed to load the new kernel and new world with the new configuration files. &prompt.root; reboot Make sure that all installed ports have first been rebuilt before old libraries are removed using the instructions in . When finished, remove any obsolete libraries to avoid conflicts with newer ones. For a more detailed description of this step, refer to . &prompt.root; make delete-old-libs single-user mode If the system can have a window of down-time, consider compiling the system in single-user mode instead of compiling the system in multi-user mode, and then dropping into single-user mode for the installation. Reinstalling the system touches a lot of important system files, all the standard system binaries, libraries, and include files. Changing these on a running system, particularly one with active users, is asking for trouble. Configuration Files make.conf This build world process uses several configuration files. The Makefile located in /usr/src describes how the programs that comprise &os; should be built and the order in which they should be built. The options available to make are described in &man.make.conf.5; and some common examples are included in /usr/share/examples/etc/make.conf. Any options which are added to /etc/make.conf will control the how make runs and builds programs. These options take effect every time make is used, including compiling applications from the Ports Collection, compiling custom C programs, or building the &os; operating system. Changes to some settings can have far-reaching and potentially surprising effects. Read the comments in both locations and keep in mind that the defaults have been chosen for a combination of performance and safety. src.conf How the operating system is built from source code is controlled by /etc/src.conf. Unlike /etc/make.conf, the contents of /etc/src.conf only take effect when the &os; operating system itself is being built. Descriptions of the many options available for this file are shown in &man.src.conf.5;. Be cautious about disabling seemingly unneeded kernel modules and build options. Sometimes there are unexpected or subtle interactions. Variables and Targets The general format for using make is as follows: &prompt.root; make -x -DVARIABLE target In this example, is an option passed to make. Refer to &man.make.1; for examples of the available options. To pass a variable, specify the variable name with . The behavior of the Makefile is controlled by variables. These can either be set in /etc/make.conf or they can be specified when using make. For example, this variable specifies that profiled libraries should not be built: &prompt.root; make -DNO_PROFILE target It corresponds with this setting in /etc/make.conf: NO_PROFILE= true # Avoid compiling profiled libraries The target tells make what to do and the Makefile defines the available targets. Some targets are used by the build process to break out the steps necessary to rebuild the system into a number of sub-steps. Having separate options is useful for two reasons. First, it allows for a build that does not affect any components of a running system. Because of this, buildworld can be safely run on a machine running in multi-user mode. It is still recommended that installworld be run in part in single-user mode, though. Secondly, it allows NFS mounts to be used to upgrade multiple machines on a network, as described in . It is possible to specify which will cause make to spawn several simultaneous processes. Since much of the compiling process is I/O-bound rather than CPU-bound, this is useful on both single CPU and multi-CPU machines. On a single-CPU machine, run the following command to have up to 4 processes running at any one time. Empirical evidence posted to the mailing lists shows this generally gives the best performance benefit. &prompt.root; make -j4 buildworld On a multi-CPU machine, try values between 6 and 10 to see how they speed things up. rebuilding world timings If any variables were specified to make buildworld, specify the same variables to make installworld. However, must never be used with installworld. For example, if this command was used: &prompt.root; make -DNO_PROFILE buildworld Install the results with: &prompt.root; make -DNO_PROFILE installworld Otherwise, the second command will try to install profiled libraries that were not built during the make buildworld phase. Merging Configuration Files Tom Rhodes Contributed by mergemaster &os; provides the &man.mergemaster.8; Bourne script to aid in determining the differences between the configuration files in /etc, and the configuration files in /usr/src/etc. This is the recommended solution for keeping the system configuration files up to date with those located in the source tree. Before using mergemaster, it is recommended to first copy the existing /etc somewhere safe. Include which does a recursive copy and which preserves times and the ownerships on files: &prompt.root; cp -Rp /etc /etc.old When run, mergemaster builds a temporary root environment, from / down, and populates it with various system configuration files. Those files are then compared to the ones currently installed in the system. Files that differ will be shown in &man.diff.1; format, with the sign representing added or modified lines, and representing lines that will be either removed completely or replaced with a new file. Refer to &man.diff.1; for more information about how file differences are shown. Next, mergemaster will display each file that differs, and present options to: delete the new file, referred to as the temporary file, install the temporary file in its unmodified state, merge the temporary file with the currently installed file, or view the results again. Choosing to delete the temporary file will tell mergemaster to keep the current file unchanged and to delete the new version. This option is not recommended. To get help at any time, type ? at the mergemaster prompt. If the user chooses to skip a file, it will be presented again after all other files have been dealt with. Choosing to install the unmodified temporary file will replace the current file with the new one. For most unmodified files, this is the best option. Choosing to merge the file will present a text editor, and the contents of both files. The files can be merged by reviewing both files side by side on the screen, and choosing parts from both to create a finished product. When the files are compared side by side, l selects the left contents and r selects contents from the right. The final output will be a file consisting of both parts, which can then be installed. This option is customarily used for files where settings have been modified by the user. Choosing to view the results again will redisplay the file differences. After mergemaster is done with the system files, it will prompt for other options. It may prompt to rebuild the password file and will finish up with an option to remove left-over temporary files. Deleting Obsolete Files and Libraries Anton Shterenlikht Based on notes provided by Deleting obsolete files and directories As a part of the &os; development lifecycle, files and their contents occasionally become obsolete. This may be because functionality is implemented elsewhere, the version number of the library has changed, or it was removed from the system entirely. These obsoleted files, libraries, and directories should be removed when updating the system. This ensures that the system is not cluttered with old files which take up unnecessary space on the storage and backup media. Additionally, if the old library has a security or stability issue, the system should be updated to the newer library to keep it safe and to prevent crashes caused by the old library. Files, directories, and libraries which are considered obsolete are listed in /usr/src/ObsoleteFiles.inc. The following instructions should be used to remove obsolete files during the system upgrade process. After the make installworld and the subsequent mergemaster have finished successfully, check for obsolete files and libraries: &prompt.root; cd /usr/src &prompt.root; make check-old If any obsolete files are found, they can be deleted using the following command: &prompt.root; make delete-old A prompt is displayed before deleting each obsolete file. To skip the prompt and let the system remove these files automatically, use BATCH_DELETE_OLD_FILES: &prompt.root; make -DBATCH_DELETE_OLD_FILES delete-old The same goal can be achieved by piping these commands through yes: &prompt.root; yes|make delete-old Warning Deleting obsolete files will break applications that still depend on those obsolete files. This is especially true for old libraries. In most cases, the programs, ports, or libraries that used the old library need to be recompiled before make delete-old-libs is executed. Utilities for checking shared library dependencies include sysutils/libchk and sysutils/bsdadminscripts. Obsolete shared libraries can conflict with newer libraries, causing messages like these: /usr/bin/ld: warning: libz.so.4, needed by /usr/local/lib/libtiff.so, may conflict with libz.so.5 /usr/bin/ld: warning: librpcsvc.so.4, needed by /usr/local/lib/libXext.so, may conflict with librpcsvc.so.5 To solve these problems, determine which port installed the library: &prompt.root; pkg which /usr/local/lib/libtiff.so /usr/local/lib/libtiff.so was installed by package tiff-3.9.4 &prompt.root; pkg which /usr/local/lib/libXext.so /usr/local/lib/libXext.so was installed by package libXext-1.1.1,1 Then deinstall, rebuild, and reinstall the port. To automate this process, ports-mgmt/portmaster can be used. After all ports are rebuilt and no longer use the old libraries, delete the old libraries using the following command: &prompt.root; make delete-old-libs If something goes wrong, it is easy to rebuild a particular piece of the system. For example, if /etc/magic was accidentally deleted as part of the upgrade or merge of /etc, file will stop working. To fix this, run: &prompt.root; cd /usr/src/usr.bin/file &prompt.root; make all install Common Questions Do I need to re-make the world for every change? It depends upon the nature of the change. For example, if svn only shows the following files as being updated: src/games/cribbage/instr.c src/games/sail/pl_main.c src/release/sysinstall/config.c src/release/sysinstall/media.c src/share/mk/bsd.port.mk it probably is not worth rebuilding the entire world. Instead, go into the appropriate sub-directories and run make all install. But if something major changes, such as src/lib/libc/stdlib, consider rebuilding world. Some users rebuild world every fortnight and let changes accumulate over that fortnight. Others only re-make those things that have changed and are careful to spot all the dependencies. It all depends on how often a user wants to upgrade and whether they are tracking &os.stable; or &os.current;. What would cause a compile to fail with lots of signal 11 signal 11 (or other signal number) errors? This normally indicates a hardware problem. Building world is an effective way to stress test hardware, especially memory. A sure indicator of a hardware issue is when make is restarted and it dies at a different point in the process. To resolve this error, swap out the components in the machine, starting with RAM, to determine which component is failing. Can /usr/obj be removed when finished? This directory contains all the object files that were produced during the compilation phase. Normally, one of the first steps in the make buildworld process is to remove this directory and start afresh. Keeping /usr/obj around when finished makes little sense, and its removal frees up a approximately 2GB of disk space. Can interrupted builds be resumed? This depends on how far into the process the problem occurs. In general, make buildworld builds new copies of essential tools and the system libraries. These tools and libraries are then installed, used to rebuild themselves, and are installed again. The rest of the system is then rebuilt with the new system tools. During the last stage, it is fairly safe to run these commands as they will not undo the work of the previous make buildworld: &prompt.root; cd /usr/src &prompt.root; make -DNO_CLEAN all If this message appears: -------------------------------------------------------------- Building everything.. -------------------------------------------------------------- in the make buildworld output, it is probably fairly safe to do so. If that message is not displayed, it is always better to be safe than sorry and to restart the build from scratch. Is it possible to speed up making the world? Several actions can speed up the build world process. For example, the entire process can be run from single-user mode. However, this will prevent users from having access to the system until the process is complete. Careful file system design or the use of ZFS datasets can make a difference. Consider putting /usr/src and /usr/obj on separate file systems. If possible, place the file systems on separate disks on separate disk controllers. When mounting /usr/src, use which prevents the file system from recording the file access time. If /usr/src is not on its own file system, consider remounting /usr with . The file system holding /usr/obj can be mounted or remounted with so that disk writes happen asynchronously. The write completes immediately, and the data is written to the disk a few seconds later. This allows writes to be clustered together, and can provide a dramatic performance boost. Keep in mind that this option makes the file system more fragile. With this option, there is an increased chance that, should power fail, the file system will be in an unrecoverable state when the machine restarts. If /usr/obj is the only directory on this file system, this is not a problem. If you have other, valuable data on the same file system, ensure that there are verified backups before enabling this option. Turn off profiling by setting NO_PROFILE=true in /etc/make.conf. Pass to &man.make.1; to run multiple processes in parallel. This usually helps on both single- and multi-processor machines. What if something goes wrong? First, make absolutely sure that the environment has no extraneous cruft from earlier builds: &prompt.root; chflags -R noschg /usr/obj/usr &prompt.root; rm -rf /usr/obj/usr &prompt.root; cd /usr/src &prompt.root; make cleandir &prompt.root; make cleandir Yes, make cleandir really should be run twice. Then, restart the whole process, starting with make buildworld. If problems persist, send the error and the output of uname -a to &a.questions;. Be prepared to answer other questions about the setup! Tracking for Multiple Machines Mike Meyer Contributed by NFS installing 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 . 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 /usr/obj and /usr/src from the build machine via NFS. For multiple build sets, /usr/src should be on one build machine, and NFS mounted on the rest. Ensure that /etc/make.conf and /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 /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 /usr/src/sys/arch/conf. On the build machine, build the kernel and world as described in , but do not install anything on the build machine. Instead, install the built kernel on the test machine. On the test machine, mount /usr/src and /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 /usr/ports via NFS to all the machines in the build set. To configure /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. Index: head/en_US.ISO8859-1/books/handbook/network-servers/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/network-servers/chapter.xml (revision 49530) +++ head/en_US.ISO8859-1/books/handbook/network-servers/chapter.xml (revision 49531) @@ -1,5785 +1,5785 @@ Network Servers Synopsis This chapter covers some of the more frequently used network services on &unix; 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 &os; 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; 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: /etc/rc scripts. Network terminology. Installation of additional third-party software (). The <application>inetd</application> 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. Configuration File Configuration of inetd is done by editing /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 /etc/rc.conf: inetd_enable="YES" To start inetd now, so that it listens for the service you configured, type: &prompt.root; service inetd start Once inetd is started, it needs to be notified whenever a modification is made to /etc/inetd.conf: Reloading the <application>inetd</application> Configuration File &prompt.root; 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: ftp stream tcp nowait root /usr/libexec/ftpd ftpd -l The seven columns in an entry are as follows: 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 /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 /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: 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, or must be specified. , and are optional. indicates whether or not the service is able to handle its own socket. socket types must use while daemons, which are usually multi-threaded, should use . usually hands off multiple sockets to a single daemon, while spawns a child daemon for each new socket. The maximum number of child daemons inetd may spawn is set by . For example, to limit ten instances of the daemon, place a /10 after . Specifying /0 allows an unlimited number of children. 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. 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;: 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 . 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 . 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 /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 in /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 in /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 in /etc/inetd.conf. Additional options are available. Refer to &man.inetd.8; for the full list of options. 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 File System (NFS) Tom Rhodes Reorganized and enhanced by Bill Swingle Written by NFS &os; 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 /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: NFS server file server UNIX clients rpcbind mountd nfsd 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. Configuring the Server NFS configuration The file systems which the NFS server will share are specified in /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. NFS export examples The following /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 /cdrom to three hosts named alpha, bravo, and charlie: /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 /etc/hosts. Refer to &man.hosts.5; if the network does not have a DNS server. The next example exports /home to three clients by IP address. This can be useful for networks without DNS or /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. /usr/home -alldirs 10.0.0.2 10.0.0.3 10.0.0.4 This next example exports /a so that two clients from different domains may access that file system. The 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. /a -maproot=root host.example.com box.example.org A client can only be specified once per file system. For example, if /usr is a single file system, these entries would be invalid as both entries specify the same host: # Invalid when /usr is one file system /usr/src client /usr/ports client The correct format for this situation is to use one entry: /usr/src /usr/ports client The following is an example of a valid export list, where /usr and /exports are local file systems: # 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 /etc/rc.conf: rpcbind_enable="YES" nfs_server_enable="YES" mountd_flags="-r" The server can be started now by running this command: &prompt.root; service nfsd start Whenever the NFS server is started, mountd also starts automatically. However, mountd only reads /etc/exports when it is started. To make subsequent /etc/exports edits take effect immediately, force mountd to reread it: &prompt.root; service mountd reload Configuring the Client To enable NFS clients, set this option in each client's /etc/rc.conf: nfs_client_enable="YES" Then, run this command on each NFS client: &prompt.root; 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 /home on server to the /mnt mount point on client: NFS mounting &prompt.root; mount server:/home /mnt The files and directories in /home will now be available on client, in the /mnt directory. To mount a remote file system each time the client boots, add it to /etc/fstab: 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 /etc/rc.conf on both the client and server: rpc_lockd_enable="YES" rpc_statd_enable="YES" Then start the applications: &prompt.root; service lockd start &prompt.root; service statd start If locking is not required on the server, the NFS client can be configured to lock locally by including when running mount. Refer to &man.mount.nfs.8; for further details. Automating Mounts with &man.amd.8; Wylie Stilwell Contributed by Chern Lee Rewritten by amd automatic mounter daemon The automatic mounter daemon, amd, automatically mounts a remote file system whenever a file or directory within that file system is accessed. File systems that are inactive for a period of time will be automatically unmounted by amd. This daemon provides an alternative to modifying /etc/fstab to list every client. It operates by attaching itself as an NFS server to the /host and /net directories. When a file is accessed within one of these directories, amd looks up the corresponding remote mount and automatically mounts it. /net is used to mount an exported file system from an IP address while /host is used to mount an export from a remote hostname. For instance, an attempt to access a file within /host/foobar/usr would tell amd to mount the /usr export on the host foobar. Mounting an Export with <application>amd</application> In this example, showmount -e shows the exported file systems that can be mounted from the NFS server, foobar: &prompt.user; showmount -e foobar Exports list on foobar: /usr 10.10.10.0 /a 10.10.10.0 &prompt.user; cd /host/foobar/usr The output from showmount shows /usr as an export. When changing directories to /host/foobar/usr, amd intercepts the request and attempts to resolve the hostname foobar. If successful, amd automatically mounts the desired export. To enable amd at boot time, add this line to /etc/rc.conf: amd_enable="YES" To start amd now: &prompt.root; service amd start Custom flags can be passed to amd from the amd_flags environment variable. By default, amd_flags is set to: amd_flags="-a /.amd_mnt -l syslog /host /etc/amd.map /net /etc/amd.map" The default options with which exports are mounted are defined in /etc/amd.map. Some of the more advanced features of amd are defined in /etc/amd.conf. Consult &man.amd.8; and &man.amd.conf.5; for more information. Automating Mounts with &man.autofs.5; The &man.autofs.5; automount facility is supported starting with &os; 10.1-RELEASE. To use the automounter functionality in older versions of &os;, use &man.amd.8; instead. This chapter only describes the &man.autofs.5; automounter. autofs automounter subsystem 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 &os; 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 /etc/auto_master. It assigns individual maps to top-level mounts. For an explanation of auto_master and the map syntax, refer to &man.auto.master.5;. There is a special automounter map mounted on /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 /net/foobar/usr would tell &man.automountd.8; to mount the /usr export from the host foobar. Mounting an Export with &man.autofs.5; In this example, showmount -e shows the exported file systems that can be mounted from the NFS server, foobar: &prompt.user; showmount -e foobar Exports list on foobar: /usr 10.10.10.0 /a 10.10.10.0 &prompt.user; cd /net/foobar/usr The output from showmount shows /usr as an export. When changing directories to /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 /etc/rc.conf: autofs_enable="YES" Then &man.autofs.5; can be started by running: &prompt.root; service automount start &prompt.root; service automountd start &prompt.root; 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 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 Information System (<acronym>NIS</acronym>) NIS Solaris HP-UX AIX Linux NetBSD OpenBSD yellow pages NIS Network Information System (NIS) is designed to centralize administration of &unix;-like systems such as &solaris;, HP-UX, &aix;, Linux, NetBSD, OpenBSD, and &os;. 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 domains 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. &os; uses version 2 of the NIS protocol. <acronym>NIS</acronym> Terms and Processes Table 28.1 summarizes the terms and important processes used by NIS: rpcbind portmap <acronym>NIS</acronym> Terminology 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-&os; 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 NIS master server NIS slave server NIS client 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 passwd, 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 master.passwd, group, and 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 &os; machines with no centralized point of administration. Each machine has its own /etc/passwd and /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: 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 <acronym>NIS</acronym> Domain Name 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-&os; 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 <acronym>NIS</acronym> Master Server - The canonical copies of all NIS files + 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 &os;, these maps are stored in /var/yp/[domainname] where [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. NIS server configuration Setting up a master NIS server can be relatively straight forward, depending on environmental needs. Since &os; provides built-in NIS support, it only needs to be enabled by adding the following lines to /etc/rc.conf: 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 /etc/rc.conf: nis_client_enable="YES" # run client stuff as well nis_client_flags="-S NIS domain,server" After saving the edits, type /etc/netstart to restart the network and apply the values defined in /etc/rc.conf. Before initializing the NIS maps, start &man.ypserv.8;: &prompt.root; service ypserv start Initializing the <acronym>NIS</acronym> Maps NIS maps NIS maps are generated from the configuration files in /etc on the NIS master, with one exception: /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: &prompt.root; cp /etc/master.passwd /var/yp/master.passwd &prompt.root; cd /var/yp &prompt.root; 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. Ensure that the /var/yp/master.passwd is neither group or world readable by setting its permissions to 600. After completing this task, initialize the NIS maps. &os; includes the &man.ypinit.8; script to do this. When generating maps for the master server, include and specify the NIS domain name: ellington&prompt.root; 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 /var/yp/Makefile from /var/yp/Makefile.dist. By default, this file assumes that the environment has a single NIS server with only &os; clients. Since test-domain has a slave server, edit this line in /var/yp/Makefile so that it begins with a comment (#): 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: &prompt.root; pw useradd jsmith &prompt.root; cd /var/yp &prompt.root; make test-domain The user could also be added using adduser jsmith instead of pw useradd smith. Setting up a <acronym>NIS</acronym> Slave Server NIS slave server To set up an NIS slave server, log on to the slave server and edit /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 (for slave) instead of (for master). This option requires the name of the NIS master in addition to the domain name, as seen in this example: coltrane&prompt.root; 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 /var/yp/test-domain which contains copies of the NIS master server's maps. Adding these /etc/crontab entries on each slave server will force the slaves to sync their maps with the maps on the master server: 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 <acronym>NIS</acronym> 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. NIS client configuration To configure a &os; machine to be an NIS client: Edit /etc/rc.conf and add the following lines in order to set the NIS domain name and start &man.ypbind.8; during network startup: 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 /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: +::::::::: 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 . 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 /etc/group: +:*:: To start the NIS client immediately, execute the following commands as the superuser: &prompt.root; /etc/netstart &prompt.root; service ypbind start After completing these steps, running ypcat passwd on the client should show the server's passwd map. <acronym>NIS</acronym> 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 /var/yp/securenets, unless &man.ypserv.8; is started with 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 securenets might look like this: # 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 securenets does not exist, ypserv will allow connections from any host. is an alternate mechanism for providing access control instead of 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 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 securenets. TCP Wrapper 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 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 /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: basie&prompt.root; 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:/sbin/nologin operator:*:2:5::0:0:System &:/:/sbin/nologin bin:*:3:7::0:0:Binaries Commands and Source,,,:/:/sbin/nologin tty:*:4:65533::0:0:Tty Sandbox:/:/sbin/nologin kmem:*:5:65533::0:0:KMem Sandbox:/:/sbin/nologin games:*:7:13::0:0:Games pseudo-user:/usr/games:/sbin/nologin news:*:8:8::0:0:News Subsystem:/:/sbin/nologin man:*:9:9::0:0:Mister Man Pages:/usr/share/man:/sbin/nologin bind:*:53:53::0:0:Bind Sandbox:/:/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:/sbin/nologin pop:*:68:6::0:0:Post Office Owner:/nonexistent:/sbin/nologin nobody:*:65534:65534::0:0:Unprivileged user:/nonexistent:/sbin/nologin -bill::::::::: +::::::::: basie&prompt.root; Using Netgroups 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; 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 User Name(s) Description alpha, beta IT department employees charlie, delta IT department apprentices echo, foxtrott, golf, ... employees able, baker, ... interns
Additional Systems 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 &os;, this map is not created by default. On the NIS master server, use an editor to create a map named /var/yp/netgroup. This example creates four netgroups to represent IT employees, IT apprentices, employees, and interns: 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. netgroups 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-&os; 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: 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: ellington&prompt.root; cd /var/yp ellington&prompt.root; make This will generate the three NIS maps netgroup, netgroup.byhost and netgroup.byuser. Use the map key option of &man.ypcat.1; to check if the new NIS maps are available: ellington&prompt.user; ypcat -k netgroup ellington&prompt.user; ypcat -k netgroup.byhost ellington&prompt.user; ypcat -k netgroup.byuser The output of the first command should resemble the contents of /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: +::::::::: with +@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: +:::::::::/sbin/nologin This line configures the client to import all entries but to replace the shell in those entries with /sbin/nologin. Make sure that extra line is placed after +@IT_EMP:::::::::. Otherwise, all user accounts imported from NIS will have /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: +@IT_EMP::::::::: +@IT_APP::::::::: +:::::::::/sbin/nologin The corresponding lines for the workstations would be: +@IT_EMP::::::::: +@USERS::::::::: +:::::::::/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: 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 /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 /sbin/nologin as shell. It is recommended to use the ALL-CAPS version of the hostname as the name of the netgroup: +@BOXNAME::::::::: +:::::::::/sbin/nologin Once this task is completed on all the machines, there is no longer a need to modify the local versions of /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: # 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 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 /etc/login.conf: 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: &prompt.root; cap_mkdb /etc/login.conf 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. Lightweight Directory Access Protocol (<acronym>LDAP</acronym>) Tom Rhodes Written by 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 &os; 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. <acronym>LDAP</acronym> 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): &prompt.user; 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. Configuring an <acronym>LDAP</acronym> Server LDAP Server &os; does not provide a built-in LDAP server. Begin the configuration by installing the net/openldap24-server package or port. Since the port has many configurable options, it is recommended that the default options are reviewed to see if the package is sufficient, and to instead compile the port if any options should be changed. In most cases, the defaults are fine. However, if SQL support is needed, this option must be enabled and the port compiled using the instructions in . Next, create the directories to hold the data and to store the certificates: &prompt.root; mkdir /var/db/openldap-data &prompt.root; mkdir /usr/local/etc/openldap/private Copy over the database configuration file: &prompt.root; cp /usr/local/etc/openldap/DB_CONFIG.example /var/db/openldap-data/DB_CONFIG The next phase is to configure the certificate authority. The following commands must be executed from /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. To create the certificate authority, start with this command and follow the prompts: &prompt.root; 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: &prompt.root; 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. Once complete, sign the key: &prompt.root; 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: &prompt.root; openssl req -days 365 -nodes -new -keyout client.key -out client.csr &prompt.root; 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. If so, the next step is to edit /usr/local/etc/openldap/slapd.conf and add the following options: TLSCipherSuite HIGH:MEDIUM:+SSLv3 TLSCertificateFile /usr/local/etc/openldap/server.crt TLSCertificateKeyFile /usr/local/etc/openldap/private/server.key TLSCACertificateFile /usr/local/etc/openldap/ca.crt Then, edit /usr/local/etc/openldap/ldap.conf and add the following lines: TLS_CACERT /usr/local/etc/openldap/ca.crt TLS_CIPHER_SUITE HIGH:MEDIUM:+SSLv3 While editing this file, uncomment the following entries and set them to the desired values: , , and . Set the to contain and . Then, add two entries pointing to the certificate authority. When finished, the entries should look similar to the following: BASE dc=example,dc=com URI ldap:// ldaps:// SIZELIMIT 12 TIMELIMIT 15 TLS_CACERT /usr/local/etc/openldap/ca.crt TLS_CIPHER_SUITE HIGH:MEDIUM:+SSLv3 The default password for the server should then be changed: &prompt.root; slappasswd -h "{SHA}" >> /usr/local/etc/openldap/slapd.conf This command will prompt for the password and, if the process does not fail, a password hash will be added to the end of slapd.conf. Several hashing formats are supported. Refer to the manual page for slappasswd for more information. Next, edit /usr/local/etc/openldap/slapd.conf and add the following lines: password-hash {sha} allow bind_v2 The in this file must be updated to match the used in /usr/local/etc/openldap/ldap.conf and should also be set. A recommended value for is something like . Before saving this file, place the in front of the password output from slappasswd and delete the old . The end result should look similar to this: TLSCipherSuite HIGH:MEDIUM:+SSLv3 TLSCertificateFile /usr/local/etc/openldap/server.crt TLSCertificateKeyFile /usr/local/etc/openldap/private/server.key TLSCACertificateFile /usr/local/etc/openldap/ca.crt rootpw {SHA}W6ph5Mm5Pz8GgiULbPgzG37mj9g= Finally, enable the OpenLDAP service in /etc/rc.conf and set the URI: slapd_enable="YES" slapd_flags="-4 -h ldaps:///" At this point the server can be started and tested: &prompt.root; service slapd start If everything is configured correctly, a search of the directory should show a successful connection with a single response as in this example: &prompt.root; ldapsearch -Z # extended LDIF # # LDAPv3 # base <dc=example,dc=com> (default) with scope subtree # filter: (objectclass=*) # requesting: ALL # # search result search: 3 result: 32 No such object # numResponses: 1 If the command fails and the configuration looks correct, stop the slapd service and restart it with debugging options: &prompt.root; service slapd stop &prompt.root; /usr/local/libexec/slapd -d -1 Once the service is responding, the directory can be populated using ldapadd. In this example, a file containing this list of users is first created. Each user should use the following format: dn: dc=example,dc=com objectclass: dcObject objectclass: organization o: Example dc: Example dn: cn=Manager,dc=example,dc=com objectclass: organizationalRole cn: Manager To import this file, specify the file name. The following command will prompt for the password specified earlier and the output should look something like this: &prompt.root; ldapadd -Z -D "cn=Manager,dc=example,dc=com" -W -f import.ldif Enter LDAP Password: adding new entry "dc=example,dc=com" adding new entry "cn=Manager,dc=example,dc=com" Verify the data was added by issuing a search on the server using ldapsearch: &prompt.user; ldapsearch -Z # extended LDIF # # LDAPv3 # base <dc=example,dc=com> (default) with scope subtree # filter: (objectclass=*) # requesting: ALL # # example.com dn: dc=example,dc=com objectClass: dcObject objectClass: organization o: Example dc: Example # Manager, example.com dn: cn=Manager,dc=example,dc=com objectClass: organizationalRole cn: Manager # search result search: 3 result: 0 Success # numResponses: 3 # numEntries: 2 At this point, the server should be configured and functioning properly. Dynamic Host Configuration Protocol (<acronym>DHCP</acronym>) Dynamic Host Configuration Protocol DHCP Internet Systems Consortium (ISC) 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. &os; includes the OpenBSD version of dhclient which is used by the client to obtain the addressing information. &os; does not install a DHCP server, but several servers are available in the &os; Ports Collection. The DHCP protocol is fully described in RFC 2131. Informational resources are also available at 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. In &os;, the &man.bpf.4; device is needed by both the DHCP server and DHCP client. This device is included in the GENERIC kernel that is installed with &os;. Users who prefer to create a custom kernel need to keep this device if DHCP is used. It should be noted that bpf also allows privileged users to run network packet sniffers on that system. Configuring a <acronym>DHCP</acronym> Client DHCP client support is included in the &os; installer, making it easy to configure a newly installed system to automatically receive its networking addressing information from an existing DHCP server. Refer to for examples of network configuration. UDP 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 &os; 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 /etc/rc.conf is used to configure background or asynchronous mode: 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 . To instead configure the system to use synchronous mode, and to pause during startup while DHCP completes, use SYNCDHCP: ifconfig_fxp0="SYNCDHCP" Additional client options are available. Search for dhclient in &man.rc.conf.5; for details. DHCP configuration files The DHCP client uses the following files: /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;. /sbin/dhclient More information about the command itself can be found in &man.dhclient.8;. /sbin/dhclient-script The &os;-specific DHCP client configuration script. It is described in &man.dhclient-script.8;, but should not need any user modification to function properly. /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;. Installing and Configuring a <acronym>DHCP</acronym> Server This section demonstrates how to configure a &os; 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 net/isc-dhcp43-server package or port. DHCP server DHCP installation The installation of net/isc-dhcp43-server installs a sample configuration file. Copy /usr/local/etc/dhcpd.conf.example to /usr/local/etc/dhcpd.conf and make any edits to this new file. DHCP dhcpd.conf 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: 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 disables dynamic DNS updates. Changing this to 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 dhcpd.conf is complete, enable the DHCP server in /etc/rc.conf: 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: &prompt.root; 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. DHCP configuration files /usr/local/sbin/dhcpd More information about the dhcpd server can be found in dhcpd(8). /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). /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. /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 net/isc-dhcp43-relay package or port. The installation includes dhcrelay(8) which provides more detail. Domain Name System (<acronym>DNS</acronym>) 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. BIND In &os; 10, the Berkeley Internet Name Domain (BIND) has been removed from the base system and replaced with Unbound. Unbound as configured in the &os; Base is a local caching resolver. BIND is still available from The Ports Collection as dns/bind99 or dns/bind98. In &os; 9 and lower, BIND is included in &os; Base. The &os; version provides enhanced security features, a new file system layout, and automated &man.chroot.8; configuration. BIND is maintained by the Internet Systems Consortium. resolver reverse DNS root zone The following table describes some of the terms associated with DNS: <acronym>DNS</acronym> Terminology Term Definition Forward DNS Mapping of hostnames to IP addresses. Origin Refers to the domain covered in a particular zone file. named, BIND Common names for the BIND name server package within &os;. 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.
zones examples 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 /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. <acronym>DNS</acronym> Server Configuration in &os; 10.0 and Later In &os; 10.0, BIND has been replaced with Unbound. Unbound is a validating caching resolver only. If an authoritative server is needed, many are available from the Ports Collection. Unbound is provided in the &os; 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 &os; Ports Collection. To enable Unbound, add the following to /etc/rc.conf: local_unbound_enable="YES" Any existing nameservers in /etc/resolv.conf will be configured as forwarders in the new Unbound configuration. 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: &prompt.user; drill -S FreeBSD.org @192.168.1.1 Once each nameserver is confirmed to support DNSSEC, start Unbound: &prompt.root; service local_unbound onestart This will take care of updating /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: &prompt.user; 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 DNS Server Configuration in &os; 9.<replaceable>X</replaceable> In &os;, the BIND daemon is called named. File Description &man.named.8; The BIND daemon. &man.rndc.8; Name server control utility. /etc/namedb Directory where BIND zone information resides. /etc/namedb/named.conf Configuration file of the daemon. Depending on how a given zone is configured on the server, the files related to that zone can be found in the master, slave, or dynamic subdirectories of the /etc/namedb directory. These files contain the DNS information that will be given out by the name server in response to queries. Starting BIND BIND starting Since BIND is installed by default, configuring it is relatively simple. The default named configuration is that of a basic resolving name server, running in a &man.chroot.8; environment, and restricted to listening on the local IPv4 loopback address (127.0.0.1). To start the server one time with this configuration, use the following command: &prompt.root; service named onestart To ensure the named daemon is started at boot each time, put the following line into the /etc/rc.conf: named_enable="YES" There are many configuration options for /etc/namedb/named.conf that are beyond the scope of this document. Other startup options for named on &os; can be found in the named_* flags in /etc/defaults/rc.conf and in &man.rc.conf.5;. The section is also a good read. Configuration Files BIND configuration files Configuration files for named currently reside in /etc/namedb directory and will need modification before use unless all that is needed is a simple resolver. This is where most of the configuration will be performed. <filename>/etc/namedb/named.conf</filename> // $FreeBSD$ // // Refer to the named.conf(5) and named(8) man pages, and the documentation // in /usr/share/doc/bind9 for more details. // // If you are going to set up an authoritative server, make sure you // understand the hairy details of how DNS works. Even with // simple mistakes, you can break connectivity for affected parties, // or cause huge amounts of useless Internet traffic. options { // All file and path names are relative to the chroot directory, // if any, and should be fully qualified. directory "/etc/namedb/working"; pid-file "/var/run/named/pid"; dump-file "/var/dump/named_dump.db"; statistics-file "/var/stats/named.stats"; // If named is being used only as a local resolver, this is a safe default. // For named to be accessible to the network, comment this option, specify // the proper IP address, or delete this option. listen-on { 127.0.0.1; }; // If you have IPv6 enabled on this system, uncomment this option for // use as a local resolver. To give access to the network, specify // an IPv6 address, or the keyword "any". // listen-on-v6 { ::1; }; // These zones are already covered by the empty zones listed below. // If you remove the related empty zones below, comment these lines out. disable-empty-zone "255.255.255.255.IN-ADDR.ARPA"; disable-empty-zone "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA"; disable-empty-zone "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA"; // If you have a DNS server around at your upstream provider, enter // its IP address here, and enable the line below. This will make you // benefit from its cache, thus reduce overall DNS traffic in the Internet. /* forwarders { 127.0.0.1; }; */ // If the 'forwarders' clause is not empty the default is to 'forward first' // which will fall back to sending a query from your local server if the name // servers in 'forwarders' do not have the answer. Alternatively you can // force your name server to never initiate queries of its own by enabling the // following line: // forward only; // If you wish to have forwarding configured automatically based on // the entries in /etc/resolv.conf, uncomment the following line and // set named_auto_forward=yes in /etc/rc.conf. You can also enable // named_auto_forward_only (the effect of which is described above). // include "/etc/namedb/auto_forward.conf"; Just as the comment says, to benefit from an uplink's cache, forwarders can be enabled here. Under normal circumstances, a name server will recursively query the Internet looking at certain name servers until it finds the answer it is looking for. Having this enabled will have it query the uplink's name server (or name server provided) first, taking advantage of its cache. If the uplink name server in question is a heavily trafficked, fast name server, enabling this may be worthwhile. 127.0.0.1 will not work here. Change this IP address to a name server at the uplink. /* Modern versions of BIND use a random UDP port for each outgoing query by default in order to dramatically reduce the possibility of cache poisoning. All users are strongly encouraged to utilize this feature, and to configure their firewalls to accommodate it. AS A LAST RESORT in order to get around a restrictive firewall policy you can try enabling the option below. Use of this option will significantly reduce your ability to withstand cache poisoning attacks, and should be avoided if at all possible. Replace NNNNN in the example with a number between 49160 and 65530. */ // query-source address * port NNNNN; }; // If you enable a local name server, do not forget to enter 127.0.0.1 // first in your /etc/resolv.conf so this server will be queried. // Also, make sure to enable it in /etc/rc.conf. // The traditional root hints mechanism. Use this, OR the slave zones below. zone "." { type hint; file "/etc/namedb/named.root"; }; /* Slaving the following zones from the root name servers has some significant advantages: 1. Faster local resolution for your users 2. No spurious traffic will be sent from your network to the roots 3. Greater resilience to any potential root server failure/DDoS On the other hand, this method requires more monitoring than the hints file to be sure that an unexpected failure mode has not incapacitated your server. Name servers that are serving a lot of clients will benefit more from this approach than individual hosts. Use with caution. To use this mechanism, uncomment the entries below, and comment the hint zone above. As documented at http://dns.icann.org/services/axfr/ these zones: "." (the root), ARPA, IN-ADDR.ARPA, IP6.ARPA, and ROOT-SERVERS.NET are available for AXFR from these servers on IPv4 and IPv6: xfr.lax.dns.icann.org, xfr.cjr.dns.icann.org */ /* zone "." { type slave; file "/etc/namedb/slave/root.slave"; masters { 192.5.5.241; // F.ROOT-SERVERS.NET. }; notify no; }; zone "arpa" { type slave; file "/etc/namedb/slave/arpa.slave"; masters { 192.5.5.241; // F.ROOT-SERVERS.NET. }; notify no; }; */ /* Serving the following zones locally will prevent any queries for these zones leaving your network and going to the root name servers. This has two significant advantages: 1. Faster local resolution for your users 2. No spurious traffic will be sent from your network to the roots */ // RFCs 1912 and 5735 (and BCP 32 for localhost) zone "localhost" { type master; file "/etc/namedb/master/localhost-forward.db"; }; zone "127.in-addr.arpa" { type master; file "/etc/namedb/master/localhost-reverse.db"; }; zone "255.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // RFC 1912-style zone for IPv6 localhost address zone "0.ip6.arpa" { type master; file "/etc/namedb/master/localhost-reverse.db"; }; // "This" Network (RFCs 1912 and 5735) zone "0.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // Private Use Networks (RFCs 1918 and 5735) zone "10.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "16.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "17.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "18.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "19.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "20.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "21.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "22.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "23.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "24.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "25.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "26.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "27.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "28.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "29.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "30.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "31.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "168.192.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // Link-local/APIPA (RFCs 3927 and 5735) zone "254.169.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IETF protocol assignments (RFCs 5735 and 5736) zone "0.0.192.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // TEST-NET-[1-3] for Documentation (RFCs 5735 and 5737) zone "2.0.192.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "100.51.198.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "113.0.203.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IPv6 Range for Documentation (RFC 3849) zone "8.b.d.0.1.0.0.2.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // Domain Names for Documentation and Testing (BCP 32) zone "test" { type master; file "/etc/namedb/master/empty.db"; }; zone "example" { type master; file "/etc/namedb/master/empty.db"; }; zone "invalid" { type master; file "/etc/namedb/master/empty.db"; }; zone "example.com" { type master; file "/etc/namedb/master/empty.db"; }; zone "example.net" { type master; file "/etc/namedb/master/empty.db"; }; zone "example.org" { type master; file "/etc/namedb/master/empty.db"; }; // Router Benchmark Testing (RFCs 2544 and 5735) zone "18.198.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "19.198.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IANA Reserved - Old Class E Space (RFC 5735) zone "240.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "241.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "242.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "243.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "244.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "245.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "246.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "247.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "248.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "249.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "250.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "251.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "252.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "253.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "254.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IPv6 Unassigned Addresses (RFC 4291) zone "1.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "3.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "4.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "5.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "6.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "7.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "8.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "9.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "a.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "b.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "c.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "d.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "e.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "0.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "1.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "2.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "3.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "4.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "5.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "6.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "7.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "8.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "9.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "a.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "b.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "0.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "1.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "2.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "3.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "4.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "5.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "6.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "7.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IPv6 ULA (RFC 4193) zone "c.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "d.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IPv6 Link Local (RFC 4291) zone "8.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "9.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "a.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "b.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IPv6 Deprecated Site-Local Addresses (RFC 3879) zone "c.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "d.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "e.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; zone "f.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; }; // IP6.INT is Deprecated (RFC 4159) zone "ip6.int" { type master; file "/etc/namedb/master/empty.db"; }; // NB: Do not use the IP addresses below, they are faked, and only // serve demonstration/documentation purposes! // // Example slave zone config entries. It can be convenient to become // a slave at least for the zone your own domain is in. Ask // your network administrator for the IP address of the responsible // master name server. // // Do not forget to include the reverse lookup zone! // This is named after the first bytes of the IP address, in reverse // order, with ".IN-ADDR.ARPA" appended, or ".IP6.ARPA" for IPv6. // // Before starting to set up a master zone, make sure you fully // understand how DNS and BIND work. There are sometimes // non-obvious pitfalls. Setting up a slave zone is usually simpler. // // NB: Do not blindly enable the examples below. :-) Use actual names // and addresses instead. /* An example dynamic zone key "exampleorgkey" { algorithm hmac-md5; secret "sf87HJqjkqh8ac87a02lla=="; }; zone "example.org" { type master; allow-update { key "exampleorgkey"; }; file "/etc/namedb/dynamic/example.org"; }; */ /* Example of a slave reverse zone zone "1.168.192.in-addr.arpa" { type slave; file "/etc/namedb/slave/1.168.192.in-addr.arpa"; masters { 192.168.1.1; }; }; */ In named.conf, these are examples of slave entries for a forward and reverse zone. For each new zone served, a new zone entry must be added to named.conf. For example, the simplest zone entry for example.org can look like: zone "example.org" { type master; file "master/example.org"; }; The zone is a master, as indicated by the statement, holding its zone information in /etc/namedb/master/example.org indicated by the statement. zone "example.org" { type slave; file "slave/example.org"; }; In the slave case, the zone information is transferred from the master name server for the particular zone, and saved in the file specified. If and when the master server dies or is unreachable, the slave name server will have the transferred zone information and will be able to serve it. Zone Files BIND zone files An example master zone file for example.org (existing within /etc/namedb/master/example.org) is as follows: $TTL 3600 ; 1 hour default TTL example.org. IN SOA ns1.example.org. admin.example.org. ( 2006051501 ; Serial 10800 ; Refresh 3600 ; Retry 604800 ; Expire 300 ; Negative Response TTL ) ; DNS Servers IN NS ns1.example.org. IN NS ns2.example.org. ; MX Records IN MX 10 mx.example.org. IN MX 20 mail.example.org. IN A 192.168.1.1 ; Machine Names localhost IN A 127.0.0.1 ns1 IN A 192.168.1.2 ns2 IN A 192.168.1.3 mx IN A 192.168.1.4 mail IN A 192.168.1.5 ; Aliases www IN CNAME example.org. Note that every hostname ending in a . is an exact hostname, whereas everything without a trailing . is relative to the origin. For example, ns1 is translated into ns1.example.org. The format of a zone file follows: recordname IN recordtype value DNS records The most commonly used DNS records: SOA start of zone authority NS an authoritative name server A a host address CNAME the canonical name for an alias MX mail exchanger PTR a domain name pointer (used in reverse DNS) example.org. IN SOA ns1.example.org. admin.example.org. ( 2006051501 ; Serial 10800 ; Refresh after 3 hours 3600 ; Retry after 1 hour 604800 ; Expire after 1 week 300 ) ; Negative Response TTL example.org. the domain name, also the origin for this zone file. ns1.example.org. the primary/authoritative name server for this zone. admin.example.org. the responsible person for this zone, email address with @ replaced. (admin@example.org becomes admin.example.org) 2006051501 the serial number of the file. This must be incremented each time the zone file is modified. Nowadays, many admins prefer a yyyymmddrr format for the serial number. 2006051501 would mean last modified 05/15/2006, the latter 01 being the first time the zone file has been modified this day. The serial number is important as it alerts slave name servers for a zone when it is updated. IN NS ns1.example.org. This is an NS entry. Every name server that is going to reply authoritatively for the zone must have one of these entries. localhost IN A 127.0.0.1 ns1 IN A 192.168.1.2 ns2 IN A 192.168.1.3 mx IN A 192.168.1.4 mail IN A 192.168.1.5 The A record indicates machine names. As seen above, ns1.example.org would resolve to 192.168.1.2. IN A 192.168.1.1 This line assigns IP address 192.168.1.1 to the current origin, in this case example.org. www IN CNAME @ The canonical name record is usually used for giving aliases to a machine. In the example, www is aliased to the master machine whose name happens to be the same as the domain name example.org (192.168.1.1). CNAMEs can never be used together with another kind of record for the same hostname. MX record IN MX 10 mail.example.org. The MX record indicates which mail servers are responsible for handling incoming mail for the zone. mail.example.org is the hostname of a mail server, and 10 is the priority of that mail server. One can have several mail servers, with priorities of 10, 20 and so on. A mail server attempting to deliver to example.org would first try the highest priority MX (the record with the lowest priority number), then the second highest, etc, until the mail can be properly delivered. For in-addr.arpa zone files (reverse DNS), the same format is used, except with PTR entries instead of A or CNAME. $TTL 3600 1.168.192.in-addr.arpa. IN SOA ns1.example.org. admin.example.org. ( 2006051501 ; Serial 10800 ; Refresh 3600 ; Retry 604800 ; Expire 300 ) ; Negative Response TTL IN NS ns1.example.org. IN NS ns2.example.org. 1 IN PTR example.org. 2 IN PTR ns1.example.org. 3 IN PTR ns2.example.org. 4 IN PTR mx.example.org. 5 IN PTR mail.example.org. This file gives the proper IP address to hostname mappings for the above fictitious domain. It is worth noting that all names on the right side of a PTR record need to be fully qualified (i.e., end in a .). Caching Name Server BIND caching name server A caching name server is a name server whose primary role is to resolve recursive queries. It simply asks queries of its own, and remembers the answers for later use. <acronym role="Domain Name Security Extensions">DNSSEC</acronym> BIND DNS security extensions Domain Name System Security Extensions, or DNSSEC for short, is a suite of specifications to protect resolving name servers from forged DNS data, such as spoofed DNS records. By using digital signatures, a resolver can verify the integrity of the record. Note that DNSSEC only provides integrity via digitally signing the Resource Records (RRs). It provides neither confidentiality nor protection against false end-user assumptions. This means that it cannot protect against people going to example.net instead of example.com. The only thing DNSSEC does is authenticate that the data has not been compromised in transit. The security of DNS is an important step in securing the Internet in general. For more in-depth details of how DNSSEC works, the relevant RFCs are a good place to start. See the list in . The following sections will demonstrate how to enable DNSSEC for an authoritative DNS server and a recursive (or caching) DNS server running BIND 9. While all versions of BIND 9 support DNSSEC, it is necessary to have at least version 9.6.2 in order to be able to use the signed root zone when validating DNS queries. This is because earlier versions lack the required algorithms to enable validation using the root zone key. It is strongly recommended to use the latest version of BIND 9.7 or later to take advantage of automatic key updating for the root key, as well as other features to automatically keep zones signed and signatures up to date. Where configurations differ between 9.6.2 and 9.7 and later, differences will be pointed out. Recursive <acronym>DNS</acronym> Server Configuration Enabling DNSSEC validation of queries performed by a recursive DNS server requires a few changes to named.conf. Before making these changes the root zone key, or trust anchor, must be acquired. Currently the root zone key is not available in a file format BIND understands, so it has to be manually converted into the proper format. The key itself can be obtained by querying the root zone for it using dig. By running &prompt.user; dig +multi +noall +answer DNSKEY . > root.dnskey the key will end up in root.dnskey. The contents should look something like this: . 93910 IN DNSKEY 257 3 8 ( AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQ bSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh /RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWA JQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXp oY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3 LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGO Yl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGc LmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0= ) ; key id = 19036 . 93910 IN DNSKEY 256 3 8 ( AwEAAcaGQEA+OJmOzfzVfoYN249JId7gx+OZMbxy69Hf UyuGBbRN0+HuTOpBxxBCkNOL+EJB9qJxt+0FEY6ZUVjE g58sRr4ZQ6Iu6b1xTBKgc193zUARk4mmQ/PPGxn7Cn5V EGJ/1h6dNaiXuRHwR+7oWh7DnzkIJChcTqlFrXDW3tjt ) ; key id = 34525 Do not be alarmed if the obtained keys differ from this example. They might have changed since these instructions were last updated. This output actually contains two keys. The first key in the listing, with the value 257 after the DNSKEY record type, is the one needed. This value indicates that this is a Secure Entry Point (SEP), commonly known as a Key Signing Key (KSK). The second key, with value 256, is a subordinate key, commonly called a Zone Signing Key (ZSK). More on the different key types later in . Now the key must be verified and formatted so that BIND can use it. To verify the key, generate a DS RR set. Create a file containing these RRs with &prompt.user; dnssec-dsfromkey -f root.dnskey . > root.ds These records use SHA-1 and SHA-256 respectively, and should look similar to the following example, where the longer is using SHA-256. . IN DS 19036 8 1 B256BD09DC8DD59F0E0F0D8541B8328DD986DF6E . IN DS 19036 8 2 49AAC11D7B6F6446702E54A1607371607A1A41855200FD2CE1CDDE32F24E8FB5 The SHA-256 RR can now be compared to the digest in https://data.iana.org/root-anchors/root-anchors.xml. To be absolutely sure that the key has not been tampered with the data in the XML file can be verified using the PGP signature in https://data.iana.org/root-anchors/root-anchors.asc. Next, the key must be formatted properly. This differs a little between BIND versions 9.6.2 and 9.7 and later. In version 9.7 support was added to automatically track changes to the key and update it as necessary. This is done using managed-keys as seen in the example below. When using the older version, the key is added using a trusted-keys statement and updates must be done manually. For BIND 9.6.2 the format should look like: trusted-keys { "." 257 3 8 "AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq QxA+Uk1ihz0="; }; For 9.7 the format will instead be: managed-keys { "." initial-key 257 3 8 "AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq QxA+Uk1ihz0="; }; The root key can now be added to named.conf either directly or by including a file containing the key. After these steps, configure BIND to do DNSSEC validation on queries by editing named.conf and adding the following to the options directive: dnssec-enable yes; dnssec-validation yes; To verify that it is actually working use dig to make a query for a signed zone using the resolver just configured. A successful reply will contain the AD flag to indicate the data was authenticated. Running a query such as &prompt.user; dig @resolver +dnssec se ds should return the DS RR for the .se zone. In the flags: section the AD flag should be set, as seen in: ... ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1 ... The resolver is now capable of authenticating DNS queries. Authoritative <acronym>DNS</acronym> Server Configuration In order to get an authoritative name server to serve a DNSSEC signed zone a little more work is required. A zone is signed using cryptographic keys which must be generated. It is possible to use only one key for this. The preferred method however is to have a strong well-protected Key Signing Key (KSK) that is not rotated very often and a Zone Signing Key (ZSK) that is rotated more frequently. Information on recommended operational practices can be found in RFC 4641: DNSSEC Operational Practices. Practices regarding the root zone can be found in DNSSEC Practice Statement for the Root Zone KSK operator and DNSSEC Practice Statement for the Root Zone ZSK operator. The KSK is used to build a chain of authority to the data in need of validation and as such is also called a Secure Entry Point (SEP) key. A message digest of this key, called a Delegation Signer (DS) record, must be published in the parent zone to establish the trust chain. How this is accomplished depends on the parent zone owner. The ZSK is used to sign the zone, and only needs to be published there. To enable DNSSEC for the example.com zone depicted in previous examples, the first step is to use dnssec-keygen to generate the KSK and ZSK key pair. This key pair can utilize different cryptographic algorithms. It is recommended to use RSA/SHA256 for the keys and 2048 bits key length should be enough. To generate the KSK for example.com, run &prompt.user; dnssec-keygen -f KSK -a RSASHA256 -b 2048 -n ZONE example.com and to generate the ZSK, run &prompt.user; dnssec-keygen -a RSASHA256 -b 2048 -n ZONE example.com dnssec-keygen outputs two files, the public and the private keys in files named similar to Kexample.com.+005+nnnnn.key (public) and Kexample.com.+005+nnnnn.private (private). The nnnnn part of the file name is a five digit key ID. Keep track of which key ID belongs to which key. This is especially important when having more than one key in a zone. It is also possible to rename the keys. For each KSK file do: &prompt.user; mv Kexample.com.+005+nnnnn.key Kexample.com.+005+nnnnn.KSK.key &prompt.user; mv Kexample.com.+005+nnnnn.private Kexample.com.+005+nnnnn.KSK.private For the ZSK files, substitute KSK for ZSK as necessary. The files can now be included in the zone file, using the $include statement. It should look something like this: $include Kexample.com.+005+nnnnn.KSK.key ; KSK $include Kexample.com.+005+nnnnn.ZSK.key ; ZSK Finally, sign the zone and tell BIND to use the signed zone file. To sign a zone dnssec-signzone is used. The command to sign the zone example.com, located in example.com.db would look similar to &prompt.user; dnssec-signzone -o example.com -k Kexample.com.+005+nnnnn.KSK example.com.db Kexample.com.+005+nnnnn.ZSK.key The key supplied to the argument is the KSK and the other key file is the ZSK that should be used in the signing. It is possible to supply more than one KSK and ZSK, which will result in the zone being signed with all supplied keys. This can be needed to supply zone data signed using more than one algorithm. The output of dnssec-signzone is a zone file with all RRs signed. This output will end up in a file with the extension .signed, such as example.com.db.signed. The DS records will also be written to a separate file dsset-example.com. To use this signed zone just modify the zone directive in named.conf to use example.com.db.signed. By default, the signatures are only valid 30 days, meaning that the zone needs to be resigned in about 15 days to be sure that resolvers are not caching records with stale signatures. It is possible to make a script and a cron job to do this. See relevant manuals for details. Be sure to keep private keys confidential, as with all cryptographic keys. When changing a key it is best to include the new key into the zone, while still signing with the old one, and then move over to using the new key to sign. After these steps are done the old key can be removed from the zone. Failure to do this might render the DNS data unavailable for a time, until the new key has propagated through the DNS hierarchy. For more information on key rollovers and other DNSSEC operational issues, see RFC 4641: DNSSEC Operational practices. Automation Using <acronym>BIND</acronym> 9.7 or Later Beginning with BIND version 9.7 a new feature called Smart Signing was introduced. This feature aims to make the key management and signing process simpler by automating parts of the task. By putting the keys into a directory called a key repository, and using the new option auto-dnssec, it is possible to create a dynamic zone which will be resigned as needed. To update this zone use nsupdate with the new option . rndc has also grown the ability to sign zones with keys in the key repository, using the option . To tell BIND to use this automatic signing and zone updating for example.com, add the following to named.conf: zone example.com { type master; key-directory "/etc/named/keys"; update-policy local; auto-dnssec maintain; file "/etc/named/dynamic/example.com.zone"; }; After making these changes, generate keys for the zone as explained in , put those keys in the key repository given as the argument to the key-directory in the zone configuration and the zone will be signed automatically. Updates to a zone configured this way must be done using nsupdate, which will take care of re-signing the zone with the new data added. For further details, see and the BIND documentation. Security Although BIND is the most common implementation of DNS, there is always the issue of security. Possible and exploitable security holes are sometimes found. While &os; automatically drops named into a &man.chroot.8; environment; there are several other security mechanisms in place which could help to lure off possible DNS service attacks. It is always good idea to read CERT's security advisories and to subscribe to the &a.security-notifications; to stay up to date with the current Internet and &os; security issues. If a problem arises, keeping sources up to date and having a fresh build of named may help. Further Reading BIND/named manual pages: &man.rndc.8; &man.named.8; &man.named.conf.5; &man.nsupdate.1; &man.dnssec-signzone.8; &man.dnssec-keygen.8; Official ISC BIND Page Official ISC BIND Forum O'Reilly DNS and BIND 5th Edition Root DNSSEC DNSSEC Trust Anchor Publication for the Root Zone RFC1034 - Domain Names - Concepts and Facilities RFC1035 - Domain Names - Implementation and Specification RFC4033 - DNS Security Introduction and Requirements RFC4034 - Resource Records for the DNS Security Extensions RFC4035 - Protocol Modifications for the DNS Security Extensions RFC4641 - DNSSEC Operational Practices RFC 5011 - Automated Updates of DNS Security (DNSSEC Trust Anchors Apache HTTP Server Murray Stokely Contributed by web servers setting up Apache The open source Apache HTTP Server is the most widely used web server. &os; does not install this web server by default, but it can be installed from the www/apache24 package or port. This section summarizes how to configure and start version 2.x of the Apache HTTP Server on &os;. For more detailed information about Apache 2.X and its configuration directives, refer to httpd.apache.org. Configuring and Starting Apache Apache configuration file In &os;, the main Apache HTTP Server configuration file is installed as /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 bin and sbin subdirectories of the server root and configuration files are stored in the 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/apache2x/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. Apache starting or stopping To launch Apache at system startup, add the following line to /etc/rc.conf: apache24_enable="YES" If Apache should be started with non-default options, the following line may be added to /etc/rc.conf to specify the needed flags: apache24_flags="" If apachectl does not report configuration errors, start httpd now: &prompt.root; 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 /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: &prompt.root; service apache24 configtest 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 httpd.conf: <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/. Apache Modules Apache modules Apache uses modules to augment the functionality provided by the basic server. Refer to http://httpd.apache.org/docs/current/mod/ for a complete listing of and the configuration details for the available modules. In &os;, some modules can be compiled with the www/apache24 port. Type make config within /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 &os; Ports Collection provides an easy way to install many modules. This section describes three of the most commonly used modules. <filename>mod_ssl</filename> web servers secure SSL cryptography The mod_ssl module uses the OpenSSL library to provide strong cryptography via the Secure Sockets Layer (SSLv3) and Transport Layer Security (TLSv1) protocols. This module provides everything necessary to request a signed certificate from a trusted certificate signing authority to run a secure web server on &os;. In &os;, mod_ssl module is enabled by default in both the package and the port. The available configuration directives are explained at http://httpd.apache.org/docs/current/mod/mod_ssl.html. <filename>mod_perl</filename> mod_perl Perl The 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 mod_perl can be installed using the www/mod_perl2 package or port. Documentation for using this module can be found at http://perl.apache.org/docs/2.0/index.html. <filename>mod_php</filename> Tom Rhodes Written by mod_php 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;, and Perl with the intention of allowing web developers to write dynamically generated webpages quickly. To gain support for PHP5 for the Apache web server, install the www/mod_php56 package or port. This will install and configure the modules required to support dynamic PHP applications. The installation will automatically add this line to /usr/local/etc/apache24/httpd.conf: LoadModule php5_module libexec/apache24/libphp5.so Then, perform a graceful restart to load the PHP module: &prompt.root; apachectl graceful The PHP support provided by www/mod_php56 is limited. Additional support can be installed using the lang/php56-extensions port which provides a menu driven interface to the available PHP extensions. Alternatively, individual extensions can be installed using the appropriate port. For instance, to add PHP support for the MySQL database server, install databases/php56-mysql. After installing an extension, the Apache server must be reloaded to pick up the new configuration changes: &prompt.root; apachectl graceful Dynamic Websites web servers dynamic 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 Python 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 mod_python, and an SQL database engine. In &os;, the www/py-django port automatically installs mod_python and supports the PostgreSQL, MySQL, or SQLite databases, with the default being SQLite. To change the database engine, type make config within /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 httpd.conf, specifying the full path to the project directory: <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 for more information on how to use Django. Ruby on Rails 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 &os;, it can be installed using the www/rubygem-rails package or port. Refer to http://guides.rubyonrails.org for more information on how to use Ruby on Rails. File Transfer Protocol (<acronym>FTP</acronym>) FTP servers The File Transfer Protocol (FTP) provides users with a simple way to transfer files to and from an FTP server. &os; includes FTP server software, ftpd, in the base system. &os; 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 &os; 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 /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 /etc/ftpchroot as described in &man.ftpchroot.5;. This file lists users and groups subject to FTP access restrictions. FTP anonymous To enable anonymous FTP access to the server, create a user named ftp on the &os; 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 /etc/ftpwelcome will be displayed to users before they reach the login prompt. After a successful login, the contents of /etc/ftpmotd will be displayed. Note that the path to this file is relative to the login environment, so the contents of ~ftp/etc/ftpmotd would be displayed for anonymous users. Once the FTP server has been configured, set the appropriate variable in /etc/rc.conf to start the service during boot: ftpd_enable="YES" To start the service now: &prompt.root; service ftpd start Test the connection to the FTP server by typing: &prompt.user; ftp localhost syslog log files FTP The ftpd daemon uses &man.syslog.3; to log messages. By default, the system log daemon will write messages related to FTP in /var/log/xferlog. The location of the FTP log can be modified by changing the following line in /etc/syslog.conf: ftp.info /var/log/xferlog FTP anonymous 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. File and Print Services for µsoft.windows; Clients (Samba) Samba server Microsoft Windows file server Windows clients print server Windows clients Samba is a popular open source software package that provides file and print services using the SMB/CIFS protocol. This protocol is built into µsoft.windows; systems. It can be added to non-µsoft.windows; 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 &os;, the Samba client libraries can be installed using the net/samba-smbclient port or package. The client provides the ability for a &os; system to access SMB/CIFS shares in a µsoft.windows; network. A &os; system can also be configured to act as a Samba server by installing the net/samba43 port or package. This allows the administrator to create SMB/CIFSshares on the &os; system which can be accessed by clients running µsoft.windows; or the Samba client libraries. Server Configuration Samba is configured in /usr/local/etc/smb4.conf. This file must be created before Samba can be used. A simple smb4.conf to share directories and printers with &windows; 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 smb4.conf. [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 /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 /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 &os; 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 NIS+ LDAP SQL database 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. <application>Samba</application> Users &os; user accounts must be mapped to the SambaSAMAccount database for &windows; clients to access the share. Map existing &os; user accounts using &man.pdbedit.8;: &prompt.root; pdbedit -a username This section has only mentioned the most commonly used settings. Refer to the Official Samba HOWTO for additional information about the available configuration options. Starting <application>Samba</application> To enable Samba at boot time, add the following line to /etc/rc.conf: samba_enable="YES" To start Samba now: &prompt.root; service samba start Starting SAMBA: removing stale tdbs : 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: winbindd_enable="YES" Samba can be stopped at any time by typing: &prompt.root; service samba stop Samba is a complex software suite with functionality that allows broad integration with µsoft.windows; networks. For more information about functionality beyond the basic configuration described here, refer to http://www.samba.org. Clock Synchronization with NTP NTP ntpd 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. &os; includes &man.ntpd.8; which can be configured to query other NTP servers in order to synchronize the clock on that machine or to provide time services to other computers in the network. The servers which are queried can be local to the network or provided by an ISP. In addition, an online list of publicly accessible NTP servers is available. When choosing a public NTP server, select one that is geographically close and review its usage policy. 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. This section describes how to configure ntpd on &os;. Further documentation can be found in /usr/share/doc/ntp/ in HTML format. <acronym>NTP</acronym> Configuration NTP ntp.conf On &os;, the built-in ntpd can be used to synchronize a system's clock. To enable ntpd at boot time, add ntpd_enable="YES" to /etc/rc.conf. Additional variables can be specified in /etc/rc.conf. Refer to &man.rc.conf.5; and &man.ntpd.8; for details. This application reads /etc/ntp.conf to determine which NTP servers to query. Here is a simple example of an /etc/ntp.conf: Sample <filename>/etc/ntp.conf</filename> server ntplocal.example.com prefer server timeserver.example.org server ntp2a.example.net driftfile /var/db/ntp.drift The format of this file is described in &man.ntp.conf.5;. The server option specifies which servers to query, with one server listed on each line. If a server entry includes prefer, that server is preferred over other servers. A response from a preferred server will be discarded if it differs significantly from other servers' responses; otherwise it will be used. The prefer argument should only be used for NTP servers that are known to be highly accurate, such as those with special time monitoring hardware. The driftfile entry specifies which file is used to store the system clock's frequency offset. ntpd uses this to automatically compensate for the clock's natural drift, allowing it to maintain a reasonably correct setting even if it is cut off from all external time sources for a period of time. This file also stores information about previous responses from NTP servers. Since this file contains internal information for NTP, it should not be modified. By default, an NTP server is accessible to any network host. The restrict option in /etc/ntp.conf can be used to control which systems can access the server. For example, to deny all machines from accessing the NTP server, add the following line to /etc/ntp.conf: restrict default ignore This will also prevent access from other NTP servers. If there is a need to synchronize with an external NTP server, allow only that specific server. Refer to &man.ntp.conf.5; for more information. To allow machines within the network to synchronize their clocks with the server, but ensure they are not allowed to configure the server or be used as peers to synchronize against, instead use: restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap where 192.168.1.0 is the local network address and 255.255.255.0 is the network's subnet mask. Multiple restrict entries are supported. For more details, refer to the Access Control Support subsection of &man.ntp.conf.5;. Once ntpd_enable="YES" has been added to /etc/rc.conf, ntpd can be started now without rebooting the system by typing: &prompt.root; service ntpd start Using <acronym>NTP</acronym> with a <acronym>PPP</acronym> 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 /etc/ppp/ppp.conf. For example: 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 /usr/share/examples/ppp/. Some Internet access providers block low-numbered ports, preventing NTP from functioning since replies never reach the machine. <acronym>iSCSI</acronym> 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 /dev/ and the device must be separately formatted and mounted. Beginning with 10.0-RELEASE, &os; provides a native, kernel-based iSCSI target and initiator. This section describes how to configure a &os; system as a target or an initiator. Configuring an <acronym>iSCSI</acronym> Target The native iSCSI target is supported starting with &os; 10.0-RELEASE. To use iSCSI in older versions of &os;, install a userspace target from the Ports Collection, such as net/istgt. This chapter only describes the native target. To configure an iSCSI target, create the /etc/ctl.conf configuration file, add a line to /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 /etc/ctl.conf configuration file. Refer to &man.ctl.conf.5; for a more complete description of this file's available options. 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 /etc/rc.conf: ctld_enable="YES" To start &man.ctld.8; now, run this command: &prompt.root; service ctld start As the &man.ctld.8; daemon is started, it reads /etc/ctl.conf. If this file is edited after the daemon starts, use this command so that the changes take effect immediately: &prompt.root; 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: 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: target iqn.2012-06.com.example:target0 { portal-group pg0 chap username1 secretsecret lun 0 { path /data/target0-0 size 4G } } Configuring an <acronym>iSCSI</acronym> Initiator The iSCSI initiator described in this section is supported starting with &os; 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 /etc/rc.conf: iscsid_enable="YES" To start &man.iscsid.8; now, run this command: &prompt.root; service iscsid start Connecting to a target can be done with or without an /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: &prompt.root; 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: 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 /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: 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: 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: 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: 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: 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: &prompt.root; 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 /etc/iscsi.conf with contents like this: 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: &prompt.root; iscsictl -An t0 Alternately, to connect to all targets defined in the configuration file, use: &prompt.root; iscsictl -Aa To make the initiator automatically connect to all targets in /etc/iscsi.conf, add the following to /etc/rc.conf: iscsictl_enable="YES" iscsictl_flags="-Aa" Index: head/en_US.ISO8859-1/books/handbook/security/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/security/chapter.xml (revision 49530) +++ head/en_US.ISO8859-1/books/handbook/security/chapter.xml (revision 49531) @@ -1,4147 +1,4147 @@ Security Tom Rhodes Rewritten by security Synopsis Security, whether physical or virtual, is a topic so broad that an entire industry has evolved around it. Hundreds of standard practices have been authored about how to secure systems and networks, and as a user of &os;, understanding how to protect against attacks and intruders is a must. In this chapter, several fundamentals and techniques will be discussed. The &os; system comes with multiple layers of security, and many more third party utilities may be added to enhance security. After reading this chapter, you will know: Basic &os; system security concepts. The various crypt mechanisms available in &os;. How to set up one-time password authentication. How to configure TCP Wrapper for use with &man.inetd.8;. How to set up Kerberos on &os;. How to configure IPsec and create a VPN. How to configure and use OpenSSH on &os;. How to use file system ACLs. How to use pkg to audit third party software packages installed from the Ports Collection. How to utilize &os; security advisories. What Process Accounting is and how to enable it on &os;. How to control user resources using login classes or the resource limits database. Before reading this chapter, you should: Understand basic &os; and Internet concepts. Additional security topics are covered elsewhere in this Handbook. For example, Mandatory Access Control is discussed in and Internet firewalls are discussed in . Introduction Security is everyone's responsibility. A weak entry point in any system could allow intruders to gain access to critical information and cause havoc on an entire network. One of the core principles of information security is the CIA triad, which stands for the Confidentiality, Integrity, and Availability of information systems. The CIA triad is a bedrock concept of computer security as customers and users expect their data to be protected. For example, a customer expects that their credit card information is securely stored (confidentiality), that their orders are not changed behind the scenes (integrity), and that they have access to their order information at all times (availablility). To provide CIA, security professionals apply a defense in depth strategy. The idea of defense in depth is to add several layers of security to prevent one single layer failing and the entire security system collapsing. For example, a system administrator cannot simply turn on a firewall and consider the network or system secure. One must also audit accounts, check the integrity of binaries, and ensure malicious tools are not installed. To implement an effective security strategy, one must understand threats and how to defend against them. What is a threat as it pertains to computer security? Threats are not limited to remote attackers who attempt to access a system without permission from a remote location. Threats also include employees, malicious software, unauthorized network devices, natural disasters, security vulnerabilities, and even competing corporations. Systems and networks can be accessed without permission, sometimes by accident, or by remote attackers, and in some cases, via corporate espionage or former employees. As a user, it is important to prepare for and admit when a mistake has led to a security breach and report possible issues to the security team. As an administrator, it is important to know of the threats and be prepared to mitigate them. When applying security to systems, it is recommended to start by securing the basic accounts and system configuration, and then to secure the network layer so that it adheres to the system policy and the organization's security procedures. Many organizations already have a security policy that covers the configuration of technology devices. The policy should include the security configuration of workstations, desktops, mobile devices, phones, production servers, and development servers. In many cases, standard operating procedures (SOPs) already exist. When in doubt, ask the security team. The rest of this introduction describes how some of these basic security configurations are performed on a &os; system. The rest of this chapter describes some specific tools which can be used when implementing a security policy on a &os; system. Preventing Logins In securing a system, a good starting point is an audit of accounts. Ensure that root has a strong password and that this password is not shared. Disable any accounts that do not need login access. To deny login access to accounts, two methods exist. The first is to lock the account. This example locks the toor account: &prompt.root; pw lock toor The second method is to prevent login access by changing the shell to /sbin/nologin. Only the superuser can change the shell for other users: &prompt.root; chsh -s /usr/sbin/nologin toor The /usr/sbin/nologin shell prevents the system from assigning a shell to the user when they attempt to login. Permitted Account Escalation In some cases, system administration needs to be shared with other users. &os; has two methods to handle this. The first one, which is not recommended, is a shared root password used by members of the wheel group. With this method, a user types su and enters the password for wheel whenever superuser access is needed. The user should then type exit to leave privileged access after finishing the commands that required administrative access. To add a user to this group, edit /etc/group and add the user to the end of the wheel entry. The user must be separated by a comma character with no space. The second, and recommended, method to permit privilege escalation is to install the security/sudo package or port. This software provides additional auditing, more fine-grained user control, and can be configured to lock users into running only the specified privileged commands. After installation, use visudo to edit /usr/local/etc/sudoers. This example creates a new webadmin group, adds the trhodes account to that group, and configures that group access to restart apache24: &prompt.root; pw groupadd webadmin -M trhodes -g 6000 &prompt.root; visudo %webadmin ALL=(ALL) /usr/sbin/service apache24 * Password Hashes Passwords are a necessary evil of technology. When they must be used, they should be complex and a powerful hash mechanism should be used to encrypt the version that is stored in the password database. &os; supports the DES, MD5, SHA256, SHA512, and Blowfish hash algorithms in its crypt() library. The default of SHA512 should not be changed to a less secure hashing algorithm, but can be changed to the more secure Blowfish algorithm. Blowfish is not part of AES and is not considered compliant with any Federal Information Processing Standards (FIPS). Its use may not be permitted in some environments. To determine which hash algorithm is used to encrypt a user's password, the superuser can view the hash for the user in the &os; password database. Each hash starts with a symbol which indicates the type of hash mechanism used to encrypt the password. If DES is used, there is no beginning symbol. For MD5, the symbol is $. For SHA256 and SHA512, the symbol is $6$. For Blowfish, the symbol is $2a$. In this example, the password for dru is hashed using the default SHA512 algorithm as the hash starts with $6$. Note that the encrypted hash, not the password itself, is stored in the password database: &prompt.root; grep dru /etc/master.passwd dru:$6$pzIjSvCAn.PBYQBA$PXpSeWPx3g5kscj3IMiM7tUEUSPmGexxta.8Lt9TGSi2lNQqYGKszsBPuGME0:1001:1001::0:0:dru:/usr/home/dru:/bin/csh The hash mechanism is set in the user's login class. For this example, the user is in the default login class and the hash algorithm is set with this line in /etc/login.conf: :passwd_format=sha512:\ To change the algorithm to Blowfish, modify that line to look like this: :passwd_format=blf:\ Then run cap_mkdb /etc/login.conf as described in . Note that this change will not affect any existing password hashes. This means that all passwords should be re-hashed by asking users to run passwd in order to change their password. For remote logins, two-factor authentication should be used. An example of two-factor authentication is something you have, such as a key, and something you know, such as the passphrase for that key. Since OpenSSH is part of the &os; base system, all network logins should be over an encrypted connection and use key-based authentication instead of passwords. For more information, refer to . Kerberos users may need to make additional changes to implement OpenSSH in their network. These changes are described in . Password Policy Enforcement Enforcing a strong password policy for local accounts is a fundamental aspect of system security. In &os;, password length, password strength, and password complexity can be implemented using built-in Pluggable Authentication Modules (PAM). This section demonstrates how to configure the minimum and maximum password length and the enforcement of mixed characters using the pam_passwdqc.so module. This module is enforced when a user changes their password. To configure this module, become the superuser and uncomment the line containing pam_passwdqc.so in /etc/pam.d/passwd. Then, edit that line to match the password policy: password requisite pam_passwdqc.so min=disabled,disabled,disabled,12,10 similar=deny retry=3 enforce=users This example sets several requirements for new passwords. The min setting controls the minimum password length. It has five values because this module defines five different types of passwords based on their complexity. Complexity is defined by the type of characters that must exist in a password, such as letters, numbers, symbols, and case. The types of passwords are described in &man.pam.passwdqc.8;. In this example, the first three types of passwords are disabled, meaning that passwords that meet those complexity requirements will not be accepted, regardless of their length. The 12 sets a minimum password policy of at least twelve characters, if the password also contains characters with three types of complexity. The 10 sets the password policy to also allow passwords of at least ten characters, if the password contains characters with four types of complexity. The similar setting denies passwords that are similar to the user's previous password. The retry setting provides a user with three opportunities to enter a new password. Once this file is saved, a user changing their password will see a message similar to the following: &prompt.user; passwd Changing local password for trhodes Old Password: You can now choose the new password. A valid password should be a mix of upper and lower case letters, digits and other characters. You can use a 12 character long password with characters from at least 3 of these 4 classes, or a 10 character long password containing characters from all the classes. Characters that form a common pattern are discarded by the check. Alternatively, if noone else can see your terminal now, you can pick this as your password: "trait-useful&knob". Enter new password: If a password that does not match the policy is entered, it will be rejected with a warning and the user will have an opportunity to try again, up to the configured number of retries. Most password policies require passwords to expire after so many days. To set a password age time in &os;, set for the user's login class in /etc/login.conf. The default login class contains an example: # :passwordtime=90d:\ So, to set an expiry of 90 days for this login class, remove the comment symbol (#), save the edit, and run cap_mkdb /etc/login.conf. To set the expiration on individual users, pass an expiration date or the number of days to expiry and a username to pw: &prompt.root; pw usermod -p 30-apr-2015 -n trhodes As seen here, an expiration date is set in the form of day, month, and year. For more information, see &man.pw.8;. Detecting Rootkits A rootkit is any unauthorized software that attempts to gain root access to a system. Once installed, this malicious software will normally open up another avenue of entry for an attacker. Realistically, once a system has been compromised by a rootkit and an investigation has been performed, the system should be reinstalled from scratch. There is tremendous risk that even the most prudent security or systems engineer will miss something an attacker left behind. A rootkit does do one thing usefulfor administrators: once detected, it is a sign that a compromise happened at some point. But, these types of applications tend to be very well hidden. This section demonstrates a tool that can be used to detect rootkits, security/rkhunter. After installation of this package or port, the system may be checked using the following command. It will produce a lot of information and will require some manual pressing of ENTER: &prompt.root; rkhunter -c After the process completes, a status message will be printed to the screen. This message will include the amount of files checked, suspect files, possible rootkits, and more. During the check, some generic security warnings may be produced about hidden files, the OpenSSH protocol selection, and known vulnerable versions of installed software. These can be handled now or after a more detailed analysis has been performed. Every administrator should know what is running on the systems they are responsible for. Third-party tools like rkhunter and sysutils/lsof, and native commands such as netstat and ps, can show a great deal of information on the system. Take notes on what is normal, ask questions when something seems out of place, and be paranoid. While preventing a compromise is ideal, detecting a compromise is a must. Binary Verification Verification of system files and binaries is important because it provides the system administration and security teams information about system changes. A software application that monitors the system for changes is called an Intrusion Detection System (IDS). &os; provides native support for a basic IDS system. While the nightly security emails will notify an administrator of changes, the information is stored locally and there is a chance that a malicious user could modify this information in order to hide their changes to the system. As such, it is recommended to create a separate set of binary signatures and store them on a read-only, root-owned directory or, preferably, on a removable USB disk or remote rsync server. The built-in mtree utility can be used to generate a specification of the contents of a directory. A seed, or a numeric constant, is used to generate the specification and is required to check that the specification has not changed. This makes it possible to determine if a file or binary has been modified. Since the seed value is unknown by an attacker, faking or checking the checksum values of files will be difficult to impossible. The following example generates a set of SHA256 hashes, one for each system binary in /bin, and saves those values to a hidden file in root's home directory, /root/.bin_chksum_mtree: &prompt.root; mtree -s 3483151339707503 -c -K cksum,sha256digest -p /bin > /root/.bin_chksum_mtree &prompt.root; mtree: /bin checksum: 3427012225 The 3483151339707503 represents the seed. This value should be remembered, but not shared. Viewing /root/.bin_cksum_mtree should yield output similar to the following: # user: root # machine: dreadnaught # tree: /bin # date: Mon Feb 3 10:19:53 2014 # . /set type=file uid=0 gid=0 mode=0555 nlink=1 flags=none . type=dir mode=0755 nlink=2 size=1024 \ time=1380277977.000000000 \133 nlink=2 size=11704 time=1380277977.000000000 \ cksum=484492447 \ sha256digest=6207490fbdb5ed1904441fbfa941279055c3e24d3a4049aeb45094596400662a cat size=12096 time=1380277975.000000000 cksum=3909216944 \ sha256digest=65ea347b9418760b247ab10244f47a7ca2a569c9836d77f074e7a306900c1e69 chflags size=8168 time=1380277975.000000000 cksum=3949425175 \ sha256digest=c99eb6fc1c92cac335c08be004a0a5b4c24a0c0ef3712017b12c89a978b2dac3 chio size=18520 time=1380277975.000000000 cksum=2208263309 \ sha256digest=ddf7c8cb92a58750a675328345560d8cc7fe14fb3ccd3690c34954cbe69fc964 chmod size=8640 time=1380277975.000000000 cksum=2214429708 \ sha256digest=a435972263bf814ad8df082c0752aa2a7bdd8b74ff01431ccbd52ed1e490bbe7 The machine's hostname, the date and time the specification was created, and the name of the user who created the specification are included in this report. There is a checksum, size, time, and SHA256 digest for each binary in the directory. To verify that the binary signatures have not changed, compare the current contents of the directory to the previously generated specification, and save the results to a file. This command requires the seed that was used to generate the original specification: &prompt.root; mtree -s 3483151339707503 -p /bin < /root/.bin_chksum_mtree >> /root/.bin_chksum_output &prompt.root; mtree: /bin checksum: 3427012225 This should produce the same checksum for /bin that was produced when the specification was created. If no changes have occurred to the binaries in this directory, the /root/.bin_chksum_output output file will be empty. To simulate a change, change the date on /bin/cat using touch and run the verification command again: &prompt.root; touch /bin/cat &prompt.root; mtree -s 3483151339707503 -p /bin < /root/.bin_chksum_mtree >> /root/.bin_chksum_output &prompt.root; more /root/.bin_chksum_output cat changed modification time expected Fri Sep 27 06:32:55 2013 found Mon Feb 3 10:28:43 2014 It is recommended to create specifications for the directories which contain binaries and configuration files, as well as any directories containing sensitive data. Typically, specifications are created for /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin, /etc, and /usr/local/etc. More advanced IDS systems exist, such as security/aide. In most cases, mtree provides the functionality administrators need. It is important to keep the seed value and the checksum output hidden from malicious users. More information about mtree can be found in &man.mtree.8;. System Tuning for Security In &os;, many system features can be tuned using sysctl. A few of the security features which can be tuned to prevent Denial of Service (DoS) attacks will be covered in this section. More information about using sysctl, including how to temporarily change values and how to make the changes permanent after testing, can be found in . Any time a setting is changed with sysctl, the chance to cause undesired harm is increased, affecting the availability of the system. All changes should be monitored and, if possible, tried on a testing system before being used on a production system. By default, the &os; kernel boots with a security level of -1. This is called insecure mode because immutable file flags may be turned off and all devices may be read from or written to. The security level will remain at -1 unless it is altered through sysctl or by a setting in the startup scripts. The security level may be increased during system startup by setting kern_securelevel_enable to YES in /etc/rc.conf, and the value of kern_securelevel to the desired security level. See &man.security.7; and &man.init.8; for more information on these settings and the available security levels. Increasing the securelevel can break Xorg and cause other issues. Be prepared to do some debugging. The net.inet.tcp.blackhole and net.inet.udp.blackhole settings can be used to drop incoming SYN packets on closed ports without sending a return RST response. The default behavior is to return an RST to show a port is closed. Changing the default provides some level of protection against ports scans, which are used to determine which applications are running on a system. Set net.inet.tcp.blackhole to 2 and net.inet.udp.blackhole to 1. Refer to &man.blackhole.4; for more information about these settings. The net.inet.icmp.drop_redirect and net.inet.ip.redirect settings help prevent against redirect attacks. A redirect attack is a type of DoS which sends mass numbers of ICMP type 5 packets. Since these packets are not required, set net.inet.icmp.drop_redirect to 1 and set net.inet.ip.redirect to 0. Source routing is a method for detecting and accessing non-routable addresses on the internal network. This should be disabled as non-routable addresses are normally not routable on purpose. To disable this feature, set net.inet.ip.sourceroute and net.inet.ip.accept_sourceroute to 0. When a machine on the network needs to send messages to all hosts on a subnet, an ICMP echo request message is sent to the broadcast address. However, there is no reason for an external host to perform such an action. To reject all external broadcast requests, set - net.inet.icmp.bmcastecho to + net.inet.icmp.bmcastecho to 0. Some additional settings are documented in &man.security.7;. One-time Passwords one-time passwords security one-time passwords By default, &os; includes support for One-time Passwords In Everything (OPIE). OPIE is designed to prevent replay attacks, in which an attacker discovers a user's password and uses it to access a system. Since a password is only used once in OPIE, a discovered password is of little use to an attacker. OPIE uses a secure hash and a challenge/response system to manage passwords. The &os; implementation uses the MD5 hash by default. OPIE uses three different types of passwords. The first is the usual &unix; or Kerberos password. The second is the one-time password which is generated by opiekey. The third type of password is the secret password which is used to generate one-time passwords. The secret password has nothing to do with, and should be different from, the &unix; password. There are two other pieces of data that are important to OPIE. One is the seed or key, consisting of two letters and five digits. The other is the iteration count, a number between 1 and 100. OPIE creates the one-time password by concatenating the seed and the secret password, applying the MD5 hash as many times as specified by the iteration count, and turning the result into six short English words which represent the one-time password. The authentication system keeps track of the last one-time password used, and the user is authenticated if the hash of the user-provided password is equal to the previous password. Because a one-way hash is used, it is impossible to generate future one-time passwords if a successfully used password is captured. The iteration count is decremented after each successful login to keep the user and the login program in sync. When the iteration count gets down to 1, OPIE must be reinitialized. There are a few programs involved in this process. A one-time password, or a consecutive list of one-time passwords, is generated by passing an iteration count, a seed, and a secret password to &man.opiekey.1;. In addition to initializing OPIE, &man.opiepasswd.1; is used to change passwords, iteration counts, or seeds. The relevant credential files in /etc/opiekeys are examined by &man.opieinfo.1; which prints out the invoking user's current iteration count and seed. This section describes four different sorts of operations. The first is how to set up one-time-passwords for the first time over a secure connection. The second is how to use opiepasswd over an insecure connection. The third is how to log in over an insecure connection. The fourth is how to generate a number of keys which can be written down or printed out to use at insecure locations. Initializing <acronym>OPIE</acronym> To initialize OPIE for the first time, run this command from a secure location: &prompt.user; opiepasswd -c Adding unfurl: Only use this method from the console; NEVER from remote. If you are using telnet, xterm, or a dial-in, type ^C now or exit with no password. Then run opiepasswd without the -c parameter. Using MD5 to compute responses. Enter new secret pass phrase: Again new secret pass phrase: ID unfurl OTP key is 499 to4268 MOS MALL GOAT ARM AVID COED The sets console mode which assumes that the command is being run from a secure location, such as a computer under the user's control or a SSH session to a computer under the user's control. When prompted, enter the secret password which will be used to generate the one-time login keys. This password should be difficult to guess and should be different than the password which is associated with the user's login account. It must be between 10 and 127 characters long. Remember this password. The ID line lists the login name (unfurl), default iteration count (499), and default seed (to4268). When logging in, the system will remember these parameters and display them, meaning that they do not have to be memorized. The last line lists the generated one-time password which corresponds to those parameters and the secret password. At the next login, use this one-time password. Insecure Connection Initialization To initialize or change the secret password on an insecure system, a secure connection is needed to some place where opiekey can be run. This might be a shell prompt on a trusted machine. An iteration count is needed, where 100 is probably a good value, and the seed can either be specified or the randomly-generated one used. On the insecure connection, the machine being initialized, use &man.opiepasswd.1;: &prompt.user; opiepasswd Updating unfurl: You need the response from an OTP generator. Old secret pass phrase: otp-md5 498 to4268 ext Response: GAME GAG WELT OUT DOWN CHAT New secret pass phrase: otp-md5 499 to4269 Response: LINE PAP MILK NELL BUOY TROY ID mark OTP key is 499 gr4269 LINE PAP MILK NELL BUOY TROY To accept the default seed, press Return. Before entering an access password, move over to the secure connection and give it the same parameters: &prompt.user; opiekey 498 to4268 Using the MD5 algorithm to compute response. Reminder: Do not use opiekey from telnet or dial-in sessions. Enter secret pass phrase: GAME GAG WELT OUT DOWN CHAT Switch back over to the insecure connection, and copy the generated one-time password over to the relevant program. Generating a Single One-time Password After initializing OPIE and logging in, a prompt like this will be displayed: &prompt.user; telnet example.com Trying 10.0.0.1... Connected to example.com Escape character is '^]'. FreeBSD/i386 (example.com) (ttypa) login: <username> otp-md5 498 gr4269 ext Password: The OPIE prompts provides a useful feature. If Return is pressed at the password prompt, the prompt will turn echo on and display what is typed. This can be useful when attempting to type in a password by hand from a printout. MS-DOS Windows MacOS At this point, generate the one-time password to answer this login prompt. This must be done on a trusted system where it is safe to run &man.opiekey.1;. There are versions of this command for &windows;, &macos; and &os;. This command needs the iteration count and the seed as command line options. Use cut-and-paste from the login prompt on the machine being logged in to. On the trusted system: &prompt.user; opiekey 498 to4268 Using the MD5 algorithm to compute response. Reminder: Do not use opiekey from telnet or dial-in sessions. Enter secret pass phrase: GAME GAG WELT OUT DOWN CHAT Once the one-time password is generated, continue to log in. Generating Multiple One-time Passwords Sometimes there is no access to a trusted machine or secure connection. In this case, it is possible to use &man.opiekey.1; to generate a number of one-time passwords beforehand. For example: &prompt.user; opiekey -n 5 30 zz99999 Using the MD5 algorithm to compute response. Reminder: Do not use opiekey from telnet or dial-in sessions. Enter secret pass phrase: <secret password> 26: JOAN BORE FOSS DES NAY QUIT 27: LATE BIAS SLAY FOLK MUCH TRIG 28: SALT TIN ANTI LOON NEAL USE 29: RIO ODIN GO BYE FURY TIC 30: GREW JIVE SAN GIRD BOIL PHI The requests five keys in sequence, and specifies what the last iteration number should be. Note that these are printed out in reverse order of use. The really paranoid might want to write the results down by hand; otherwise, print the list. Each line shows both the iteration count and the one-time password. Scratch off the passwords as they are used. Restricting Use of &unix; Passwords OPIE can restrict the use of &unix; passwords based on the IP address of a login session. The relevant file is /etc/opieaccess, which is present by default. Refer to &man.opieaccess.5; for more information on this file and which security considerations to be aware of when using it. Here is a sample opieaccess: permit 192.168.0.0 255.255.0.0 This line allows users whose IP source address (which is vulnerable to spoofing) matches the specified value and mask, to use &unix; passwords at any time. If no rules in opieaccess are matched, the default is to deny non-OPIE logins. TCP Wrapper TomRhodesWritten by TCP Wrapper TCP Wrapper is a host-based access control system which extends the abilities of . It can be configured to provide logging support, return messages, and connection restrictions for the server daemons under the control of inetd. Refer to &man.tcpd.8; for more information about TCP Wrapper and its features. TCP Wrapper should not be considered a replacement for a properly configured firewall. Instead, TCP Wrapper should be used in conjunction with a firewall and other security enhancements in order to provide another layer of protection in the implementation of a security policy. Initial Configuration To enable TCP Wrapper in &os;, add the following lines to /etc/rc.conf: inetd_enable="YES" inetd_flags="-Ww" Then, properly configure /etc/hosts.allow. Unlike other implementations of TCP Wrapper, the use of hosts.deny is deprecated in &os;. All configuration options should be placed in /etc/hosts.allow. In the simplest configuration, daemon connection policies are set to either permit or block, depending on the options in /etc/hosts.allow. The default configuration in &os; is to allow all connections to the daemons started with inetd. Basic configuration usually takes the form of daemon : address : action, where daemon is the daemon which inetd started, address is a valid hostname, IP address, or an IPv6 address enclosed in brackets ([ ]), and action is either allow or deny. TCP Wrapper uses a first rule match semantic, meaning that the configuration file is scanned from the beginning for a matching rule. When a match is found, the rule is applied and the search process stops. For example, to allow POP3 connections via the mail/qpopper daemon, the following lines should be appended to hosts.allow: # This line is required for POP3 connections: qpopper : ALL : allow Whenever this file is edited, restart inetd: &prompt.root; service inetd restart Advanced Configuration TCP Wrapper provides advanced options to allow more control over the way connections are handled. In some cases, it may be appropriate to return a comment to certain hosts or daemon connections. In other cases, a log entry should be recorded or an email sent to the administrator. Other situations may require the use of a service for local connections only. This is all possible through the use of configuration options known as wildcards, expansion characters, and external command execution. Suppose that a situation occurs where a connection should be denied yet a reason should be sent to the host who attempted to establish that connection. That action is possible with . When a connection attempt is made, executes a shell command or script. An example exists in hosts.allow: # The rest of the daemons are protected. ALL : ALL \ : severity auth.info \ : twist /bin/echo "You are not welcome to use %d from %h." In this example, the message You are not allowed to use daemon name from hostname. will be returned for any daemon not configured in hosts.allow. This is useful for sending a reply back to the connection initiator right after the established connection is dropped. Any message returned must be wrapped in quote (") characters. It may be possible to launch a denial of service attack on the server if an attacker floods these daemons with connection requests. Another possibility is to use . Like , implicitly denies the connection and may be used to run external shell commands or scripts. Unlike , will not send a reply back to the host who established the connection. For example, consider the following configuration: # We do not allow connections from example.com: ALL : .example.com \ : spawn (/bin/echo %a from %h attempted to access %d >> \ /var/log/connections.log) \ : deny This will deny all connection attempts from *.example.com and log the hostname, IP address, and the daemon to which access was attempted to /var/log/connections.log. This example uses the substitution characters %a and %h. Refer to &man.hosts.access.5; for the complete list. To match every instance of a daemon, domain, or IP address, use ALL. Another wildcard is PARANOID which may be used to match any host which provides an IP address that may be forged because the IP address differs from its resolved hostname. In this example, all connection requests to Sendmail which have an IP address that varies from its hostname will be denied: # Block possibly spoofed requests to sendmail: sendmail : PARANOID : deny Using the PARANOID wildcard will result in denied connections if the client or server has a broken DNS setup. To learn more about wildcards and their associated functionality, refer to &man.hosts.access.5;. When adding new configuration lines, make sure that any unneeded entries for that daemon are commented out in hosts.allow. <application>Kerberos</application> Tillman Hodgson Contributed by Mark Murray Based on a contribution by Kerberos is a network authentication protocol which was originally created by the Massachusetts Institute of Technology (MIT) as a way to securely provide authentication across a potentially hostile network. The Kerberos protocol uses strong cryptography so that both a client and server can prove their identity without sending any unencrypted secrets over the network. Kerberos can be described as an identity-verifying proxy system and as a trusted third-party authentication system. After a user authenticates with Kerberos, their communications can be encrypted to assure privacy and data integrity. The only function of Kerberos is to provide the secure authentication of users and servers on the network. It does not provide authorization or auditing functions. It is recommended that Kerberos be used with other security methods which provide authorization and audit services. The current version of the protocol is version 5, described in RFC 4120. Several free implementations of this protocol are available, covering a wide range of operating systems. MIT continues to develop their Kerberos package. It is commonly used in the US as a cryptography product, and has historically been subject to US export regulations. In &os;, MIT Kerberos is available as the security/krb5 package or port. The Heimdal Kerberos implementation was explicitly developed outside of the US to avoid export regulations. The Heimdal Kerberos distribution is included in the base &os; installation, and another distribution with more configurable options is available as security/heimdal in the Ports Collection. In Kerberos users and services are identified as principals which are contained within an administrative grouping, called a realm. A typical user principal would be of the form user@REALM (realms are traditionally uppercase). This section provides a guide on how to set up Kerberos using the Heimdal distribution included in &os;. For purposes of demonstrating a Kerberos installation, the name spaces will be as follows: The DNS domain (zone) will be example.org. The Kerberos realm will be EXAMPLE.ORG. Use real domain names when setting up Kerberos, even if it will run internally. This avoids DNS problems and assures inter-operation with other Kerberos realms. Setting up a Heimdal <acronym>KDC</acronym> Kerberos5 Key Distribution Center The Key Distribution Center (KDC) is the centralized authentication service that Kerberos provides, the trusted third party of the system. It is the computer that issues Kerberos tickets, which are used for clients to authenticate to servers. Because the KDC is considered trusted by all other computers in the Kerberos realm, it has heightened security concerns. Direct access to the KDC should be limited. While running a KDC requires few computing resources, a dedicated machine acting only as a KDC is recommended for security reasons. To begin setting up a KDC, add these lines to /etc/rc.conf: kdc_enable="YES" kadmind_enable="YES" Next, edit /etc/krb5.conf as follows: [libdefaults] default_realm = EXAMPLE.ORG [realms] EXAMPLE.ORG = { kdc = kerberos.example.org admin_server = kerberos.example.org } [domain_realm] .example.org = EXAMPLE.ORG In this example, the KDC will use the fully-qualified hostname kerberos.example.org. The hostname of the KDC must be resolvable in the DNS. Kerberos can also use the DNS to locate KDCs, instead of a [realms] section in /etc/krb5.conf. For large organizations that have their own DNS servers, the above example could be trimmed to: [libdefaults] default_realm = EXAMPLE.ORG [domain_realm] .example.org = EXAMPLE.ORG With the following lines being included in the example.org zone file: _kerberos._udp IN SRV 01 00 88 kerberos.example.org. _kerberos._tcp IN SRV 01 00 88 kerberos.example.org. _kpasswd._udp IN SRV 01 00 464 kerberos.example.org. _kerberos-adm._tcp IN SRV 01 00 749 kerberos.example.org. _kerberos IN TXT EXAMPLE.ORG In order for clients to be able to find the Kerberos services, they must have either a fully configured /etc/krb5.conf or a minimally configured /etc/krb5.conf and a properly configured DNS server. Next, create the Kerberos database which contains the keys of all principals (users and hosts) encrypted with a master password. It is not required to remember this password as it will be stored in /var/heimdal/m-key; it would be reasonable to use a 45-character random password for this purpose. To create the master key, run kstash and enter a password: &prompt.root; kstash Master key: xxxxxxxxxxxxxxxxxxxxxxx Verifying password - Master key: xxxxxxxxxxxxxxxxxxxxxxx Once the master key has been created, the database should be initialized. The Kerberos administrative tool &man.kadmin.8; can be used on the KDC in a mode that operates directly on the database, without using the &man.kadmind.8; network service, as kadmin -l. This resolves the chicken-and-egg problem of trying to connect to the database before it is created. At the kadmin prompt, use init to create the realm's initial database: &prompt.root; kadmin -l kadmin> init EXAMPLE.ORG Realm max ticket life [unlimited]: Lastly, while still in kadmin, create the first principal using add. Stick to the default options for the principal for now, as these can be changed later with modify. Type ? at the prompt to see the available options. kadmin> add tillman Max ticket life [unlimited]: Max renewable life [unlimited]: Attributes []: Password: xxxxxxxx Verifying password - Password: xxxxxxxx Next, start the KDC services by running service kdc start and service kadmind start. While there will not be any kerberized daemons running at this point, it is possible to confirm that the KDC is functioning by obtaining a ticket for the principal that was just created: &prompt.user; kinit tillman tillman@EXAMPLE.ORG's Password: Confirm that a ticket was successfully obtained using klist: &prompt.user; klist Credentials cache: FILE:/tmp/krb5cc_1001 Principal: tillman@EXAMPLE.ORG Issued Expires Principal Aug 27 15:37:58 2013 Aug 28 01:37:58 2013 krbtgt/EXAMPLE.ORG@EXAMPLE.ORG The temporary ticket can be destroyed when the test is finished: &prompt.user; kdestroy Configuring a Server to Use <application>Kerberos</application> Kerberos5 enabling services The first step in configuring a server to use Kerberos authentication is to ensure that it has the correct configuration in /etc/krb5.conf. The version from the KDC can be used as-is, or it can be regenerated on the new system. Next, create /etc/krb5.keytab on the server. This is the main part of Kerberizing a service — it corresponds to generating a secret shared between the service and the KDC. The secret is a cryptographic key, stored in a keytab. The keytab contains the server's host key, which allows it and the KDC to verify each others' identity. It must be transmitted to the server in a secure fashion, as the security of the server can be broken if the key is made public. Typically, the keytab is generated on an administrator's trusted machine using kadmin, then securely transferred to the server, e.g., with &man.scp.1;; it can also be created directly on the server if that is consistent with the desired security policy. It is very important that the keytab is transmitted to the server in a secure fashion: if the key is known by some other party, that party can impersonate any user to the server! Using kadmin on the server directly is convenient, because the entry for the host principal in the KDC database is also created using kadmin. Of course, kadmin is a kerberized service; a Kerberos ticket is needed to authenticate to the network service, but to ensure that the user running kadmin is actually present (and their session has not been hijacked), kadmin will prompt for the password to get a fresh ticket. The principal authenticating to the kadmin service must be permitted to use the kadmin interface, as specified in kadmind.acl. See the section titled Remote administration in info heimdal for details on designing access control lists. Instead of enabling remote kadmin access, the administrator could securely connect to the KDC via the local console or &man.ssh.1;, and perform administration locally using kadmin -l. After installing /etc/krb5.conf, use add --random-key in kadmin. This adds the server's host principal to the database, but does not extract a copy of the host principal key to a keytab. To generate the keytab, use ext to extract the server's host principal key to its own keytab: &prompt.root; kadmin kadmin> add --random-key host/myserver.example.org Max ticket life [unlimited]: Max renewable life [unlimited]: Principal expiration time [never]: Password expiration time [never]: Attributes []: kadmin> ext_keytab host/myserver.example.org kadmin> exit Note that ext_keytab stores the extracted key in /etc/krb5.keytab by default. This is good when being run on the server being kerberized, but the --keytab path/to/file argument should be used when the keytab is being extracted elsewhere: &prompt.root; kadmin kadmin> ext_keytab --keytab=/tmp/example.keytab host/myserver.example.org kadmin> exit The keytab can then be securely copied to the server using &man.scp.1; or a removable media. Be sure to specify a non-default keytab name to avoid inserting unneeded keys into the system's keytab. At this point, the server can read encrypted messages from the KDC using its shared key, stored in krb5.keytab. It is now ready for the Kerberos-using services to be enabled. One of the most common such services is &man.sshd.8;, which supports Kerberos via the GSS-API. In /etc/ssh/sshd_config, add the line: GSSAPIAuthentication yes After making this change, &man.sshd.8; must be restared for the new configuration to take effect: service sshd restart. Configuring a Client to Use <application>Kerberos</application> Kerberos5 configure clients As it was for the server, the client requires configuration in /etc/krb5.conf. Copy the file in place (securely) or re-enter it as needed. Test the client by using kinit, klist, and kdestroy from the client to obtain, show, and then delete a ticket for an existing principal. Kerberos applications should also be able to connect to Kerberos enabled servers. If that does not work but obtaining a ticket does, the problem is likely with the server and not with the client or the KDC. In the case of kerberized &man.ssh.1;, GSS-API is disabled by default, so test using ssh -o GSSAPIAuthentication=yes hostname. When testing a Kerberized application, try using a packet sniffer such as tcpdump to confirm that no sensitive information is sent in the clear. Various Kerberos client applications are available. With the advent of a bridge so that applications using SASL for authentication can use GSS-API mechanisms as well, large classes of client applications can use Kerberos for authentication, from Jabber clients to IMAP clients. .k5login .k5users Users within a realm typically have their Kerberos principal mapped to a local user account. Occasionally, one needs to grant access to a local user account to someone who does not have a matching Kerberos principal. For example, tillman@EXAMPLE.ORG may need access to the local user account webdevelopers. Other principals may also need access to that local account. The .k5login and .k5users files, placed in a user's home directory, can be used to solve this problem. For example, if the following .k5login is placed in the home directory of webdevelopers, both principals listed will have access to that account without requiring a shared password: tillman@example.org jdoe@example.org Refer to &man.ksu.1; for more information about .k5users. <acronym>MIT</acronym> Differences The major difference between the MIT and Heimdal implementations is that kadmin has a different, but equivalent, set of commands and uses a different protocol. If the KDC is MIT, the Heimdal version of kadmin cannot be used to administer the KDC remotely, and vice versa. Client applications may also use slightly different command line options to accomplish the same tasks. Following the instructions at http://web.mit.edu/Kerberos/www/ is recommended. Be careful of path issues: the MIT port installs into /usr/local/ by default, and the &os; system applications run instead of the MIT versions if PATH lists the system directories first. When using MIT Kerberos as a KDC on &os;, the following edits should also be made to rc.conf: kerberos5_server="/usr/local/sbin/krb5kdc" kadmind5_server="/usr/local/sbin/kadmind" kerberos5_server_flags="" kerberos5_server_enable="YES" kadmind5_server_enable="YES" <application>Kerberos</application> Tips, Tricks, and Troubleshooting When configuring and troubleshooting Kerberos, keep the following points in mind: When using either Heimdal or MIT Kerberos from ports, ensure that the PATH lists the port's versions of the client applications before the system versions. If all the computers in the realm do not have synchronized time settings, authentication may fail. describes how to synchronize clocks using NTP. If the hostname is changed, the host/ principal must be changed and the keytab updated. This also applies to special keytab entries like the HTTP/ principal used for Apache's www/mod_auth_kerb. All hosts in the realm must be both forward and reverse resolvable in DNS or, at a minimum, exist in /etc/hosts. CNAMEs will work, but the A and PTR records must be correct and in place. The error message for unresolvable hosts is not intuitive: Kerberos5 refuses authentication because Read req failed: Key table entry not found. Some operating systems that act as clients to the KDC do not set the permissions for ksu to be setuid root. This means that ksu does not work. This is a permissions problem, not a KDC error. With MIT Kerberos, to allow a principal to have a ticket life longer than the default lifetime of ten hours, use modify_principal at the &man.kadmin.8; prompt to change the maxlife of both the principal in question and the krbtgt principal. The principal can then use kinit -l to request a ticket with a longer lifetime. When running a packet sniffer on the KDC to aid in troubleshooting while running kinit from a workstation, the Ticket Granting Ticket (TGT) is sent immediately, even before the password is typed. This is because the Kerberos server freely transmits a TGT to any unauthorized request. However, every TGT is encrypted in a key derived from the user's password. When a user types their password, it is not sent to the KDC, it is instead used to decrypt the TGT that kinit already obtained. If the decryption process results in a valid ticket with a valid time stamp, the user has valid Kerberos credentials. These credentials include a session key for establishing secure communications with the Kerberos server in the future, as well as the actual TGT, which is encrypted with the Kerberos server's own key. This second layer of encryption allows the Kerberos server to verify the authenticity of each TGT. Host principals can have a longer ticket lifetime. If the user principal has a lifetime of a week but the host being connected to has a lifetime of nine hours, the user cache will have an expired host principal and the ticket cache will not work as expected. When setting up krb5.dict to prevent specific bad passwords from being used as described in &man.kadmind.8;, remember that it only applies to principals that have a password policy assigned to them. The format used in krb5.dict is one string per line. Creating a symbolic link to /usr/share/dict/words might be useful. Mitigating <application>Kerberos</application> Limitations Kerberos5 limitations and shortcomings Since Kerberos is an all or nothing approach, every service enabled on the network must either be modified to work with Kerberos or be otherwise secured against network attacks. This is to prevent user credentials from being stolen and re-used. An example is when Kerberos is enabled on all remote shells but the non-Kerberized POP3 mail server sends passwords in plain text. The KDC is a single point of failure. By design, the KDC must be as secure as its master password database. The KDC should have absolutely no other services running on it and should be physically secure. The danger is high because Kerberos stores all passwords encrypted with the same master key which is stored as a file on the KDC. A compromised master key is not quite as bad as one might fear. The master key is only used to encrypt the Kerberos database and as a seed for the random number generator. As long as access to the KDC is secure, an attacker cannot do much with the master key. If the KDC is unavailable, network services are unusable as authentication cannot be performed. This can be alleviated with a single master KDC and one or more slaves, and with careful implementation of secondary or fall-back authentication using PAM. Kerberos allows users, hosts and services to authenticate between themselves. It does not have a mechanism to authenticate the KDC to the users, hosts, or services. This means that a trojanned kinit could record all user names and passwords. File system integrity checking tools like security/tripwire can alleviate this. Resources and Further Information Kerberos5 external resources The Kerberos FAQ Designing an Authentication System: a Dialog in Four Scenes RFC 4120, The Kerberos Network Authentication Service (V5) MIT Kerberos home page Heimdal Kerberos home page OpenSSL TomRhodesWritten by security OpenSSL OpenSSL is an open source implementation of the SSL and TLS protocols. It provides an encryption transport layer on top of the normal communications layer, allowing it to be intertwined with many network applications and services. The version of OpenSSL included in &os; supports the Secure Sockets Layer v2/v3 (SSLv2/SSLv3) and Transport Layer Security v1 (TLSv1) network security protocols and can be used as a general cryptographic library. OpenSSL is often used to encrypt authentication of mail clients and to secure web based transactions such as credit card payments. Some ports, such as www/apache24 and databases/postgresql91-server, include a compile option for building with OpenSSL. &os; provides two versions of OpenSSL: one in the base system and one in the Ports Collection. Users can choose which version to use by default for other ports using the following knobs: WITH_OPENSSL_PORT: when set, the port will use OpenSSL from the security/openssl port, even if the version in the base system is up to date or newer. WITH_OPENSSL_BASE: when set, the port will compile against OpenSSL provided by the base system. Another common use of OpenSSL is to provide certificates for use with software applications. Certificates can be used to verify the credentials of a company or individual. If a certificate has not been signed by an external Certificate Authority (CA), such as http://www.verisign.com, the application that uses the certificate will produce a warning. There is a cost associated with obtaining a signed certificate and using a signed certificate is not mandatory as certificates can be self-signed. However, using an external authority will prevent warnings and can put users at ease. This section demonstrates how to create and use certificates on a &os; system. Refer to for an example of how to create a CA for signing one's own certificates. For more information about SSL, read the free OpenSSL Cookbook. Generating Certificates OpenSSL certificate generation To generate a certificate that will be signed by an external CA, issue the following command and input the information requested at the prompts. This input information will be written to the certificate. At the Common Name prompt, input the fully qualified name for the system that will use the certificate. If this name does not match the server, the application verifying the certificate will issue a warning to the user, rendering the verification provided by the certificate as useless. &prompt.root; openssl req -new -nodes -out req.pem -keyout cert.key -sha256 -newkey rsa:2048 Generating a 2048 bit RSA private key ..................+++ .............................................................+++ writing new private key to 'cert.key' ----- You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:US State or Province Name (full name) [Some-State]:PA Locality Name (eg, city) []:Pittsburgh Organization Name (eg, company) [Internet Widgits Pty Ltd]:My Company Organizational Unit Name (eg, section) []:Systems Administrator Common Name (eg, YOUR name) []:localhost.example.org Email Address []:trhodes@FreeBSD.org Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []: An optional company name []:Another Name Other options, such as the expire time and alternate encryption algorithms, are available when creating a certificate. A complete list of options is described in &man.openssl.1;. This command will create two files in the current directory. The certificate request, req.pem, can be sent to a CA who will validate the entered credentials, sign the request, and return the signed certificate. The second file, cert.key, is the private key for the certificate and should be stored in a secure location. If this falls in the hands of others, it can be used to impersonate the user or the server. Alternately, if a signature from a CA is not required, a self-signed certificate can be created. First, generate the RSA key: &prompt.root; openssl genrsa -rand -genkey -out cert.key 2048 0 semi-random bytes loaded Generating RSA private key, 2048 bit long modulus .............................................+++ .................................................................................................................+++ e is 65537 (0x10001) Use this key to create a self-signed certificate. Follow the usual prompts for creating a certificate: &prompt.root; openssl req -new -x509 -days 365 -key cert.key -out cert.crt -sha256 You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:US State or Province Name (full name) [Some-State]:PA Locality Name (eg, city) []:Pittsburgh Organization Name (eg, company) [Internet Widgits Pty Ltd]:My Company Organizational Unit Name (eg, section) []:Systems Administrator Common Name (e.g. server FQDN or YOUR name) []:localhost.example.org Email Address []:trhodes@FreeBSD.org This will create two new files in the current directory: a private key file cert.key, and the certificate itself, cert.crt. These should be placed in a directory, preferably under /etc/ssl/, which is readable only by root. Permissions of 0700 are appropriate for these files and can be set using chmod. Using Certificates One use for a certificate is to encrypt connections to the Sendmail mail server in order to prevent the use of clear text authentication. Some mail clients will display an error if the user has not installed a local copy of the certificate. Refer to the documentation included with the software for more information on certificate installation. In &os; 10.0-RELEASE and above, it is possible to create a self-signed certificate for Sendmail automatically. To enable this, add the following lines to /etc/rc.conf: sendmail_enable="YES" sendmail_cert_create="YES" sendmail_cert_cn="localhost.example.org" This will automatically create a self-signed certificate, /etc/mail/certs/host.cert, a signing key, /etc/mail/certs/host.key, and a CA certificate, /etc/mail/certs/cacert.pem. The certificate will use the Common Name specified in . After saving the edits, restart Sendmail: &prompt.root; service sendmail restart If all went well, there will be no error messages in /var/log/maillog. For a simple test, connect to the mail server's listening port using telnet: &prompt.root; telnet example.com 25 Trying 192.0.34.166... Connected to example.com. Escape character is '^]'. 220 example.com ESMTP Sendmail 8.14.7/8.14.7; Fri, 18 Apr 2014 11:50:32 -0400 (EDT) ehlo example.com 250-example.com Hello example.com [192.0.34.166], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 250-DSN 250-ETRN 250-AUTH LOGIN PLAIN 250-STARTTLS 250-DELIVERBY 250 HELP quit 221 2.0.0 example.com closing connection Connection closed by foreign host. If the STARTTLS line appears in the output, everything is working correctly. <acronym>VPN</acronym> over <acronym>IPsec</acronym> Nik Clayton
nik@FreeBSD.org
Written by Hiten M. Pandya
hmp@FreeBSD.org
Written by IPsec Internet Protocol Security (IPsec) is a set of protocols which sit on top of the Internet Protocol (IP) layer. It allows two or more hosts to communicate in a secure manner by authenticating and encrypting each IP packet of a communication session. The &os; IPsec network stack is based on the http://www.kame.net/ implementation and supports both IPv4 and IPv6 sessions. IPsec ESP IPsec AH IPsec is comprised of the following sub-protocols: Encapsulated Security Payload (ESP): this protocol protects the IP packet data from third party interference by encrypting the contents using symmetric cryptography algorithms such as Blowfish and 3DES. Authentication Header (AH): this protocol protects the IP packet header from third party interference and spoofing by computing a cryptographic checksum and hashing the IP packet header fields with a secure hashing function. This is then followed by an additional header that contains the hash, to allow the information in the packet to be authenticated. IP Payload Compression Protocol (IPComp): this protocol tries to increase communication performance by compressing the IP payload in order to reduce the amount of data sent. These protocols can either be used together or separately, depending on the environment. VPN virtual private network VPN IPsec supports two modes of operation. The first mode, Transport Mode, protects communications between two hosts. The second mode, Tunnel Mode, is used to build virtual tunnels, commonly known as Virtual Private Networks (VPNs). Consult &man.ipsec.4; for detailed information on the IPsec subsystem in &os;. To add IPsec support to the kernel, add the following options to the custom kernel configuration file and rebuild the kernel using the instructions in : kernel options IPSEC options IPSEC #IP security device crypto kernel options IPSEC_DEBUG If IPsec debugging support is desired, the following kernel option should also be added: options IPSEC_DEBUG #debug for IP security This rest of this chapter demonstrates the process of setting up an IPsec VPN between a home network and a corporate network. In the example scenario: Both sites are connected to the Internet through a gateway that is running &os;. The gateway on each network has at least one external IP address. In this example, the corporate LAN's external IP address is 172.16.5.4 and the home LAN's external IP address is 192.168.1.12. The internal addresses of the two networks can be either public or private IP addresses. However, the address space must not collide. For example, both networks cannot use 192.168.1.x. In this example, the corporate LAN's internal IP address is 10.246.38.1 and the home LAN's internal IP address is 10.0.0.5. Configuring a <acronym>VPN</acronym> on &os; Tom Rhodes
trhodes@FreeBSD.org
Written by To begin, security/ipsec-tools must be installed from the Ports Collection. This software provides a number of applications which support the configuration. The next requirement is to create two &man.gif.4; pseudo-devices which will be used to tunnel packets and allow both networks to communicate properly. As root, run the following commands, replacing internal and external with the real IP addresses of the internal and external interfaces of the two gateways: &prompt.root; ifconfig gif0 create &prompt.root; ifconfig gif0 internal1 internal2 &prompt.root; ifconfig gif0 tunnel external1 external2 Verify the setup on each gateway, using ifconfig. Here is the output from Gateway 1: gif0: flags=8051 mtu 1280 tunnel inet 172.16.5.4 --> 192.168.1.12 inet6 fe80::2e0:81ff:fe02:5881%gif0 prefixlen 64 scopeid 0x6 inet 10.246.38.1 --> 10.0.0.5 netmask 0xffffff00 Here is the output from Gateway 2: gif0: flags=8051 mtu 1280 tunnel inet 192.168.1.12 --> 172.16.5.4 inet 10.0.0.5 --> 10.246.38.1 netmask 0xffffff00 inet6 fe80::250:bfff:fe3a:c1f%gif0 prefixlen 64 scopeid 0x4 Once complete, both internal IP addresses should be reachable using &man.ping.8;: priv-net# ping 10.0.0.5 PING 10.0.0.5 (10.0.0.5): 56 data bytes 64 bytes from 10.0.0.5: icmp_seq=0 ttl=64 time=42.786 ms 64 bytes from 10.0.0.5: icmp_seq=1 ttl=64 time=19.255 ms 64 bytes from 10.0.0.5: icmp_seq=2 ttl=64 time=20.440 ms 64 bytes from 10.0.0.5: icmp_seq=3 ttl=64 time=21.036 ms --- 10.0.0.5 ping statistics --- 4 packets transmitted, 4 packets received, 0% packet loss round-trip min/avg/max/stddev = 19.255/25.879/42.786/9.782 ms corp-net# ping 10.246.38.1 PING 10.246.38.1 (10.246.38.1): 56 data bytes 64 bytes from 10.246.38.1: icmp_seq=0 ttl=64 time=28.106 ms 64 bytes from 10.246.38.1: icmp_seq=1 ttl=64 time=42.917 ms 64 bytes from 10.246.38.1: icmp_seq=2 ttl=64 time=127.525 ms 64 bytes from 10.246.38.1: icmp_seq=3 ttl=64 time=119.896 ms 64 bytes from 10.246.38.1: icmp_seq=4 ttl=64 time=154.524 ms --- 10.246.38.1 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 28.106/94.594/154.524/49.814 ms As expected, both sides have the ability to send and receive ICMP packets from the privately configured addresses. Next, both gateways must be told how to route packets in order to correctly send traffic from either network. The following commands will achieve this goal: &prompt.root; corp-net# route add 10.0.0.0 10.0.0.5 255.255.255.0 &prompt.root; corp-net# route add net 10.0.0.0: gateway 10.0.0.5 &prompt.root; priv-net# route add 10.246.38.0 10.246.38.1 255.255.255.0 &prompt.root; priv-net# route add host 10.246.38.0: gateway 10.246.38.1 At this point, internal machines should be reachable from each gateway as well as from machines behind the gateways. Again, use &man.ping.8; to confirm: corp-net# ping 10.0.0.8 PING 10.0.0.8 (10.0.0.8): 56 data bytes 64 bytes from 10.0.0.8: icmp_seq=0 ttl=63 time=92.391 ms 64 bytes from 10.0.0.8: icmp_seq=1 ttl=63 time=21.870 ms 64 bytes from 10.0.0.8: icmp_seq=2 ttl=63 time=198.022 ms 64 bytes from 10.0.0.8: icmp_seq=3 ttl=63 time=22.241 ms 64 bytes from 10.0.0.8: icmp_seq=4 ttl=63 time=174.705 ms --- 10.0.0.8 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 21.870/101.846/198.022/74.001 ms priv-net# ping 10.246.38.107 PING 10.246.38.1 (10.246.38.107): 56 data bytes 64 bytes from 10.246.38.107: icmp_seq=0 ttl=64 time=53.491 ms 64 bytes from 10.246.38.107: icmp_seq=1 ttl=64 time=23.395 ms 64 bytes from 10.246.38.107: icmp_seq=2 ttl=64 time=23.865 ms 64 bytes from 10.246.38.107: icmp_seq=3 ttl=64 time=21.145 ms 64 bytes from 10.246.38.107: icmp_seq=4 ttl=64 time=36.708 ms --- 10.246.38.107 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 21.145/31.721/53.491/12.179 ms Setting up the tunnels is the easy part. Configuring a secure link is a more in depth process. The following configuration uses pre-shared (PSK) RSA keys. Other than the IP addresses, the /usr/local/etc/racoon/racoon.conf on both gateways will be identical and look similar to: path pre_shared_key "/usr/local/etc/racoon/psk.txt"; #location of pre-shared key file log debug; #log verbosity setting: set to 'notify' when testing and debugging is complete padding # options are not to be changed { maximum_length 20; randomize off; strict_check off; exclusive_tail off; } timer # timing options. change as needed { counter 5; interval 20 sec; persend 1; # natt_keepalive 15 sec; phase1 30 sec; phase2 15 sec; } listen # address [port] that racoon will listen on { isakmp 172.16.5.4 [500]; isakmp_natt 172.16.5.4 [4500]; } remote 192.168.1.12 [500] { exchange_mode main,aggressive; doi ipsec_doi; situation identity_only; my_identifier address 172.16.5.4; peers_identifier address 192.168.1.12; lifetime time 8 hour; passive off; proposal_check obey; # nat_traversal off; generate_policy off; proposal { encryption_algorithm blowfish; hash_algorithm md5; authentication_method pre_shared_key; lifetime time 30 sec; dh_group 1; } } sainfo (address 10.246.38.0/24 any address 10.0.0.0/24 any) # address $network/$netmask $type address $network/$netmask $type ( $type being any or esp) { # $network must be the two internal networks you are joining. pfs_group 1; lifetime time 36000 sec; encryption_algorithm blowfish,3des; authentication_algorithm hmac_md5,hmac_sha1; compression_algorithm deflate; } For descriptions of each available option, refer to the manual page for racoon.conf. The Security Policy Database (SPD) needs to be configured so that &os; and racoon are able to encrypt and decrypt network traffic between the hosts. This can be achieved with a shell script, similar to the following, on the corporate gateway. This file will be used during system initialization and should be saved as /usr/local/etc/racoon/setkey.conf. flush; spdflush; # To the home network spdadd 10.246.38.0/24 10.0.0.0/24 any -P out ipsec esp/tunnel/172.16.5.4-192.168.1.12/use; spdadd 10.0.0.0/24 10.246.38.0/24 any -P in ipsec esp/tunnel/192.168.1.12-172.16.5.4/use; Once in place, racoon may be started on both gateways using the following command: &prompt.root; /usr/local/sbin/racoon -F -f /usr/local/etc/racoon/racoon.conf -l /var/log/racoon.log The output should be similar to the following: corp-net# /usr/local/sbin/racoon -F -f /usr/local/etc/racoon/racoon.conf Foreground mode. 2006-01-30 01:35:47: INFO: begin Identity Protection mode. 2006-01-30 01:35:48: INFO: received Vendor ID: KAME/racoon 2006-01-30 01:35:55: INFO: received Vendor ID: KAME/racoon 2006-01-30 01:36:04: INFO: ISAKMP-SA established 172.16.5.4[500]-192.168.1.12[500] spi:623b9b3bd2492452:7deab82d54ff704a 2006-01-30 01:36:05: INFO: initiate new phase 2 negotiation: 172.16.5.4[0]192.168.1.12[0] 2006-01-30 01:36:09: INFO: IPsec-SA established: ESP/Tunnel 192.168.1.12[0]->172.16.5.4[0] spi=28496098(0x1b2d0e2) 2006-01-30 01:36:09: INFO: IPsec-SA established: ESP/Tunnel 172.16.5.4[0]->192.168.1.12[0] spi=47784998(0x2d92426) 2006-01-30 01:36:13: INFO: respond new phase 2 negotiation: 172.16.5.4[0]192.168.1.12[0] 2006-01-30 01:36:18: INFO: IPsec-SA established: ESP/Tunnel 192.168.1.12[0]->172.16.5.4[0] spi=124397467(0x76a279b) 2006-01-30 01:36:18: INFO: IPsec-SA established: ESP/Tunnel 172.16.5.4[0]->192.168.1.12[0] spi=175852902(0xa7b4d66) To ensure the tunnel is working properly, switch to another console and use &man.tcpdump.1; to view network traffic using the following command. Replace em0 with the network interface card as required: &prompt.root; tcpdump -i em0 host 172.16.5.4 and dst 192.168.1.12 Data similar to the following should appear on the console. If not, there is an issue and debugging the returned data will be required. 01:47:32.021683 IP corporatenetwork.com > 192.168.1.12.privatenetwork.com: ESP(spi=0x02acbf9f,seq=0xa) 01:47:33.022442 IP corporatenetwork.com > 192.168.1.12.privatenetwork.com: ESP(spi=0x02acbf9f,seq=0xb) 01:47:34.024218 IP corporatenetwork.com > 192.168.1.12.privatenetwork.com: ESP(spi=0x02acbf9f,seq=0xc) At this point, both networks should be available and seem to be part of the same network. Most likely both networks are protected by a firewall. To allow traffic to flow between them, rules need to be added to pass packets. For the &man.ipfw.8; firewall, add the following lines to the firewall configuration file: ipfw add 00201 allow log esp from any to any ipfw add 00202 allow log ah from any to any ipfw add 00203 allow log ipencap from any to any ipfw add 00204 allow log udp from any 500 to any The rule numbers may need to be altered depending on the current host configuration. For users of &man.pf.4; or &man.ipf.8;, the following rules should do the trick: pass in quick proto esp from any to any pass in quick proto ah from any to any pass in quick proto ipencap from any to any pass in quick proto udp from any port = 500 to any port = 500 pass in quick on gif0 from any to any pass out quick proto esp from any to any pass out quick proto ah from any to any pass out quick proto ipencap from any to any pass out quick proto udp from any port = 500 to any port = 500 pass out quick on gif0 from any to any Finally, to allow the machine to start support for the VPN during system initialization, add the following lines to /etc/rc.conf: ipsec_enable="YES" ipsec_program="/usr/local/sbin/setkey" ipsec_file="/usr/local/etc/racoon/setkey.conf" # allows setting up spd policies on boot racoon_enable="yes" OpenSSH ChernLeeContributed by OpenSSH security OpenSSH OpenSSH is a set of network connectivity tools used to provide secure access to remote machines. Additionally, TCP/IP connections can be tunneled or forwarded securely through SSH connections. OpenSSH encrypts all traffic to effectively eliminate eavesdropping, connection hijacking, and other network-level attacks. OpenSSH is maintained by the OpenBSD project and is installed by default in &os;. It is compatible with both SSH version 1 and 2 protocols. When data is sent over the network in an unencrypted form, network sniffers anywhere in between the client and server can steal user/password information or data transferred during the session. OpenSSH offers a variety of authentication and encryption methods to prevent this from happening. More information about OpenSSH is available from http://www.openssh.com/. This section provides an overview of the built-in client utilities to securely access other systems and securely transfer files from a &os; system. It then describes how to configure a SSH server on a &os; system. More information is available in the man pages mentioned in this chapter. Using the SSH Client Utilities OpenSSH client To log into a SSH server, use ssh and specify a username that exists on that server and the IP address or hostname of the server. If this is the first time a connection has been made to the specified server, the user will be prompted to first verify the server's fingerprint: &prompt.root; ssh user@example.com The authenticity of host 'example.com (10.0.0.1)' can't be established. ECDSA key fingerprint is 25:cc:73:b5:b3:96:75:3d:56:19:49:d2:5c:1f:91:3b. Are you sure you want to continue connecting (yes/no)? yes Permanently added 'example.com' (ECDSA) to the list of known hosts. Password for user@example.com: user_password SSH utilizes a key fingerprint system to verify the authenticity of the server when the client connects. When the user accepts the key's fingerprint by typing yes when connecting for the first time, a copy of the key is saved to .ssh/known_hosts in the user's home directory. Future attempts to login are verified against the saved key and ssh will display an alert if the server's key does not match the saved key. If this occurs, the user should first verify why the key has changed before continuing with the connection. By default, recent versions of OpenSSH only accept SSHv2 connections. By default, the client will use version 2 if possible and will fall back to version 1 if the server does not support version 2. To force ssh to only use the specified protocol, include or . Additional options are described in &man.ssh.1;. OpenSSH secure copy &man.scp.1; Use &man.scp.1; to securely copy a file to or from a remote machine. This example copies COPYRIGHT on the remote system to a file of the same name in the current directory of the local system: &prompt.root; scp user@example.com:/COPYRIGHT COPYRIGHT Password for user@example.com: ******* COPYRIGHT 100% |*****************************| 4735 00:00 &prompt.root; Since the fingerprint was already verified for this host, the server's key is automatically checked before prompting for the user's password. The arguments passed to scp are similar to cp. The file or files to copy is the first argument and the destination to copy to is the second. Since the file is fetched over the network, one or more of the file arguments takes the form . Be aware when copying directories recursively that scp uses , whereas cp uses . To open an interactive session for copying files, use sftp. Refer to &man.sftp.1; for a list of available commands while in an sftp session. Key-based Authentication Instead of using passwords, a client can be configured to connect to the remote machine using keys. To generate RSA authentication keys, use ssh-keygen. To generate a public and private key pair, specify the type of key and follow the prompts. It is recommended to protect the keys with a memorable, but hard to guess passphrase. &prompt.user; ssh-keygen -t rsa Generating public/private rsa key pair. Enter file in which to save the key (/home/user/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/user/.ssh/id_rsa. Your public key has been saved in /home/user/.ssh/id_rsa.pub. The key fingerprint is: SHA256:54Xm9Uvtv6H4NOo6yjP/YCfODryvUU7yWHzMqeXwhq8 user@host.example.com The key's randomart image is: +---[RSA 2048]----+ | | | | | | | . o.. | | .S*+*o | | . O=Oo . . | | = Oo= oo..| | .oB.* +.oo.| | =OE**.o..=| +----[SHA256]-----+ Type a passphrase here. It can contain spaces and symbols. Retype the passphrase to verify it. The private key is stored in ~/.ssh/id_rsa and the public key is stored in ~/.ssh/id_rsa.pub. The public key must be copied to ~/.ssh/authorized_keys on the remote machine for key-based authentication to work. Many users believe that keys are secure by design and will use a key without a passphrase. This is dangerous behavior. An administrator can verify that a key pair is protected by a passphrase by viewing the private key manually. If the private key file contains the word ENCRYPTED, the key owner is using a passphrase. In addition, to better secure end users, from may be placed in the public key file. For example, adding from="192.168.10.5" in front of the ssh-rsa prefix will only allow that specific user to log in from that IP address. The options and files vary with different versions of OpenSSH. To avoid problems, consult &man.ssh-keygen.1;. If a passphrase is used, the user is prompted for the passphrase each time a connection is made to the server. To load SSH keys into memory and remove the need to type the passphrase each time, use &man.ssh-agent.1; and &man.ssh-add.1;. Authentication is handled by ssh-agent, using the private keys that are loaded into it. ssh-agent can be used to launch another application like a shell or a window manager. To use ssh-agent in a shell, start it with a shell as an argument. Add the identity by running ssh-add and entering the passphrase for the private key. The user will then be able to ssh to any host that has the corresponding public key installed. For example: &prompt.user; ssh-agent csh &prompt.user; ssh-add Enter passphrase for key '/usr/home/user/.ssh/id_rsa': Identity added: /usr/home/user/.ssh/id_rsa (/usr/home/user/.ssh/id_rsa) &prompt.user; Enter the passphrase for the key. To use ssh-agent in &xorg;, add an entry for it in ~/.xinitrc. This provides the ssh-agent services to all programs launched in &xorg;. An example ~/.xinitrc might look like this: exec ssh-agent startxfce4 This launches ssh-agent, which in turn launches XFCE, every time &xorg; starts. Once &xorg; has been restarted so that the changes can take effect, run ssh-add to load all of the SSH keys. <acronym>SSH</acronym> Tunneling OpenSSH tunneling OpenSSH has the ability to create a tunnel to encapsulate another protocol in an encrypted session. The following command tells ssh to create a tunnel for telnet: &prompt.user; ssh -2 -N -f -L 5023:localhost:23 user@foo.example.com &prompt.user; This example uses the following options: Forces ssh to use version 2 to connect to the server. Indicates no command, or tunnel only. If omitted, ssh initiates a normal session. Forces ssh to run in the background. Indicates a local tunnel in localport:remotehost:remoteport format. The login name to use on the specified remote SSH server. An SSH tunnel works by creating a listen socket on localhost on the specified localport. It then forwards any connections received on localport via the SSH connection to the specified remotehost:remoteport. In the example, port 5023 on the client is forwarded to port 23 on the remote machine. Since port 23 is used by telnet, this creates an encrypted telnet session through an SSH tunnel. This method can be used to wrap any number of insecure TCP protocols such as SMTP, POP3, and FTP, as seen in the following examples. Create a Secure Tunnel for <acronym>SMTP</acronym> &prompt.user; ssh -2 -N -f -L 5025:localhost:25 user@mailserver.example.com user@mailserver.example.com's password: ***** &prompt.user; telnet localhost 5025 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. 220 mailserver.example.com ESMTP This can be used in conjunction with ssh-keygen and additional user accounts to create a more seamless SSH tunneling environment. Keys can be used in place of typing a password, and the tunnels can be run as a separate user. Secure Access of a <acronym>POP3</acronym> Server In this example, there is an SSH server that accepts connections from the outside. On the same network resides a mail server running a POP3 server. To check email in a secure manner, create an SSH connection to the SSH server and tunnel through to the mail server: &prompt.user; ssh -2 -N -f -L 2110:mail.example.com:110 user@ssh-server.example.com user@ssh-server.example.com's password: ****** Once the tunnel is up and running, point the email client to send POP3 requests to localhost on port 2110. This connection will be forwarded securely across the tunnel to mail.example.com. Bypassing a Firewall Some firewalls filter both incoming and outgoing connections. For example, a firewall might limit access from remote machines to ports 22 and 80 to only allow SSH and web surfing. This prevents access to any other service which uses a port other than 22 or 80. The solution is to create an SSH connection to a machine outside of the network's firewall and use it to tunnel to the desired service: &prompt.user; ssh -2 -N -f -L 8888:music.example.com:8000 user@unfirewalled-system.example.org user@unfirewalled-system.example.org's password: ******* In this example, a streaming Ogg Vorbis client can now be pointed to localhost port 8888, which will be forwarded over to music.example.com on port 8000, successfully bypassing the firewall. Enabling the SSH Server OpenSSH enabling In addition to providing built-in SSH client utilities, a &os; system can be configured as an SSH server, accepting connections from other SSH clients. To see if sshd is operating, use the &man.service.8; command: &prompt.root; service sshd status If the service is not running, add the following line to /etc/rc.conf. sshd_enable="YES" This will start sshd, the daemon program for OpenSSH, the next time the system boots. To start it now: &prompt.root; service sshd start The first time sshd starts on a &os; system, the system's host keys will be automatically created and the fingerprint will be displayed on the console. Provide users with the fingerprint so that they can verify it the first time they connect to the server. Refer to &man.sshd.8; for the list of available options when starting sshd and a more complete discussion about authentication, the login process, and the various configuration files. At this point, the sshd should be available to all users with a username and password on the system. SSH Server Security While sshd is the most widely used remote administration facility for &os;, brute force and drive by attacks are common to any system exposed to public networks. Several additional parameters are available to prevent the success of these attacks and will be described in this section. It is a good idea to limit which users can log into the SSH server and from where using the AllowUsers keyword in the OpenSSH server configuration file. For example, to only allow root to log in from 192.168.1.32, add this line to /etc/ssh/sshd_config: AllowUsers root@192.168.1.32 To allow admin to log in from anywhere, list that user without specifying an IP address: AllowUsers admin Multiple users should be listed on the same line, like so: AllowUsers root@192.168.1.32 admin After making changes to /etc/ssh/sshd_config, tell sshd to reload its configuration file by running: &prompt.root; service sshd reload When this keyword is used, it is important to list each user that needs to log into this machine. Any user that is not specified in that line will be locked out. Also, the keywords used in the OpenSSH server configuration file are case-sensitive. If the keyword is not spelled correctly, including its case, it will be ignored. Always test changes to this file to make sure that the edits are working as expected. Refer to &man.sshd.config.5; to verify the spelling and use of the available keywords. In addition, users may be forced to use two factor authentication via the use of a public and private key. When required, the user may generate a key pair through the use of &man.ssh-keygen.1; and send the administrator the public key. This key file will be placed in the authorized_keys as described above in the client section. To force the users to use keys only, the following option may be configured: AuthenticationMethods publickey Do not confuse /etc/ssh/sshd_config with /etc/ssh/ssh_config (note the extra d in the first filename). The first file configures the server and the second file configures the client. Refer to &man.ssh.config.5; for a listing of the available client settings. Access Control Lists TomRhodesContributed by ACL Access Control Lists (ACLs) extend the standard &unix; permission model in a &posix;.1e compatible way. This permits an administrator to take advantage of a more fine-grained permissions model. The &os; GENERIC kernel provides ACL support for UFS file systems. Users who prefer to compile a custom kernel must include the following option in their custom kernel configuration file: options UFS_ACL If this option is not compiled in, a warning message will be displayed when attempting to mount a file system with ACL support. ACLs rely on extended attributes which are natively supported in UFS2. This chapter describes how to enable ACL support and provides some usage examples. Enabling <acronym>ACL</acronym> Support ACLs are enabled by the mount-time administrative flag, , which may be added to /etc/fstab. The mount-time flag can also be automatically set in a persistent manner using &man.tunefs.8; to modify a superblock ACLs flag in the file system header. In general, it is preferred to use the superblock flag for several reasons: The superblock flag cannot be changed by a remount using as it requires a complete umount and fresh mount. This means that ACLs cannot be enabled on the root file system after boot. It also means that ACL support on a file system cannot be changed while the system is in use. Setting the superblock flag causes the file system to always be mounted with ACLs enabled, even if there is not an fstab entry or if the devices re-order. This prevents accidental mounting of the file system without ACL support. It is desirable to discourage accidental mounting without ACLs enabled because nasty things can happen if ACLs are enabled, then disabled, then re-enabled without flushing the extended attributes. In general, once ACLs are enabled on a file system, they should not be disabled, as the resulting file protections may not be compatible with those intended by the users of the system, and re-enabling ACLs may re-attach the previous ACLs to files that have since had their permissions changed, resulting in unpredictable behavior. File systems with ACLs enabled will show a plus (+) sign in their permission settings: drwx------ 2 robert robert 512 Dec 27 11:54 private drwxrwx---+ 2 robert robert 512 Dec 23 10:57 directory1 drwxrwx---+ 2 robert robert 512 Dec 22 10:20 directory2 drwxrwx---+ 2 robert robert 512 Dec 27 11:57 directory3 drwxr-xr-x 2 robert robert 512 Nov 10 11:54 public_html In this example, directory1, directory2, and directory3 are all taking advantage of ACLs, whereas public_html is not. Using <acronym>ACL</acronym>s File system ACLs can be viewed using getfacl. For instance, to view the ACL settings on test: &prompt.user; getfacl test #file:test #owner:1001 #group:1001 user::rw- group::r-- other::r-- To change the ACL settings on this file, use setfacl. To remove all of the currently defined ACLs from a file or file system, include . However, the preferred method is to use as it leaves the basic fields required for ACLs to work. &prompt.user; setfacl -k test To modify the default ACL entries, use : &prompt.user; setfacl -m u:trhodes:rwx,group:web:r--,o::--- test In this example, there were no pre-defined entries, as they were removed by the previous command. This command restores the default options and assigns the options listed. If a user or group is added which does not exist on the system, an Invalid argument error will be displayed. Refer to &man.getfacl.1; and &man.setfacl.1; for more information about the options available for these commands. Monitoring Third Party Security Issues TomRhodesContributed by pkg In recent years, the security world has made many improvements to how vulnerability assessment is handled. The threat of system intrusion increases as third party utilities are installed and configured for virtually any operating system available today. Vulnerability assessment is a key factor in security. While &os; releases advisories for the base system, doing so for every third party utility is beyond the &os; Project's capability. There is a way to mitigate third party vulnerabilities and warn administrators of known security issues. A &os; add on utility known as pkg includes options explicitly for this purpose. pkg polls a database for security issues. The database is updated and maintained by the &os; Security Team and ports developers. Please refer to instructions for installing pkg. Installation provides &man.periodic.8; configuration files for maintaining the pkg audit database, and provides a programmatic method of keeping it updated. This functionality is enabled if daily_status_security_pkgaudit_enable is set to YES in &man.periodic.conf.5;. Ensure that daily security run emails, which are sent to root's email account, are being read. After installation, and to audit third party utilities as part of the Ports Collection at any time, an administrator may choose to update the database and view known vulnerabilities of installed packages by invoking: &prompt.root; pkg audit -F pkg displays messages any published vulnerabilities in installed packages: Affected package: cups-base-1.1.22.0_1 Type of problem: cups-base -- HPGL buffer overflow vulnerability. Reference: <http://www.FreeBSD.org/ports/portaudit/40a3bca2-6809-11d9-a9e7-0001020eed82.html> 1 problem(s) in your installed packages found. You are advised to update or deinstall the affected package(s) immediately. By pointing a web browser to the displayed URL, an administrator may obtain more information about the vulnerability. This will include the versions affected, by &os; port version, along with other web sites which may contain security advisories. pkg is a powerful utility and is extremely useful when coupled with ports-mgmt/portmaster. &os; Security Advisories TomRhodesContributed by &os; Security Advisories Like many producers of quality operating systems, the &os; Project has a security team which is responsible for determining the End-of-Life (EoL) date for each &os; release and to provide security updates for supported releases which have not yet reached their EoL. More information about the &os; security team and the supported releases is available on the &os; security page. One task of the security team is to respond to reported security vulnerabilities in the &os; operating system. Once a vulnerability is confirmed, the security team verifies the steps necessary to fix the vulnerability and updates the source code with the fix. It then publishes the details as a Security Advisory. Security advisories are published on the &os; website and mailed to the &a.security-notifications.name;, &a.security.name;, and &a.announce.name; mailing lists. This section describes the format of a &os; security advisory. Format of a Security Advisory Here is an example of a &os; security advisory: ============================================================================= -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-14:04.bind Security Advisory The FreeBSD Project Topic: BIND remote denial of service vulnerability Category: contrib Module: bind Announced: 2014-01-14 Credits: ISC Affects: FreeBSD 8.x and FreeBSD 9.x Corrected: 2014-01-14 19:38:37 UTC (stable/9, 9.2-STABLE) 2014-01-14 19:42:28 UTC (releng/9.2, 9.2-RELEASE-p3) 2014-01-14 19:42:28 UTC (releng/9.1, 9.1-RELEASE-p10) 2014-01-14 19:38:37 UTC (stable/8, 8.4-STABLE) 2014-01-14 19:42:28 UTC (releng/8.4, 8.4-RELEASE-p7) 2014-01-14 19:42:28 UTC (releng/8.3, 8.3-RELEASE-p14) CVE Name: CVE-2014-0591 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://security.FreeBSD.org/>. I. Background BIND 9 is an implementation of the Domain Name System (DNS) protocols. The named(8) daemon is an Internet Domain Name Server. II. Problem Description Because of a defect in handling queries for NSEC3-signed zones, BIND can crash with an "INSIST" failure in name.c when processing queries possessing certain properties. This issue only affects authoritative nameservers with at least one NSEC3-signed zone. Recursive-only servers are not at risk. III. Impact An attacker who can send a specially crafted query could cause named(8) to crash, resulting in a denial of service. IV. Workaround No workaround is available, but systems not running authoritative DNS service with at least one NSEC3-signed zone using named(8) are not vulnerable. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. 2) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 8.3, 8.4, 9.1, 9.2-RELEASE and 8.4-STABLE] # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-release.patch # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-release.patch.asc # gpg --verify bind-release.patch.asc [FreeBSD 9.2-STABLE] # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-stable-9.patch # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-stable-9.patch.asc # gpg --verify bind-stable-9.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch Recompile the operating system using buildworld and installworld as described in <URL:http://www.FreeBSD.org/handbook/makeworld.html>. Restart the applicable daemons, or reboot the system. 3) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/8/ r260646 releng/8.3/ r260647 releng/8.4/ r260647 stable/9/ r260646 releng/9.1/ r260647 releng/9.2/ r260647 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: <URL:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:https://kb.isc.org/article/AA-01078> <URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0591> The latest revision of this advisory is available at <URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:04.bind.asc> -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJS1ZTYAAoJEO1n7NZdz2rnOvQP/2/68/s9Cu35PmqNtSZVVxVG ZSQP5EGWx/lramNf9566iKxOrLRMq/h3XWcC4goVd+gZFrvITJSVOWSa7ntDQ7TO XcinfRZ/iyiJbs/Rg2wLHc/t5oVSyeouyccqODYFbOwOlk35JjOTMUG1YcX+Zasg ax8RV+7Zt1QSBkMlOz/myBLXUjlTZ3Xg2FXVsfFQW5/g2CjuHpRSFx1bVNX6ysoG 9DT58EQcYxIS8WfkHRbbXKh9I1nSfZ7/Hky/kTafRdRMrjAgbqFgHkYTYsBZeav5 fYWKGQRJulYfeZQ90yMTvlpF42DjCC3uJYamJnwDIu8OhS1WRBI8fQfr9DRzmRua OK3BK9hUiScDZOJB6OqeVzUTfe7MAA4/UwrDtTYQ+PqAenv1PK8DZqwXyxA9ThHb zKO3OwuKOVHJnKvpOcr+eNwo7jbnHlis0oBksj/mrq2P9m2ueF9gzCiq5Ri5Syag Wssb1HUoMGwqU0roS8+pRpNC8YgsWpsttvUWSZ8u6Vj/FLeHpiV3mYXPVMaKRhVm 067BA2uj4Th1JKtGleox+Em0R7OFbCc/9aWC67wiqI6KRyit9pYiF3npph+7D5Eq 7zPsUdDd+qc+UTiLp3liCRp5w6484wWdhZO6wRtmUgxGjNkxFoNnX8CitzF8AaqO UWWemqWuz3lAZuORQ9KX =OQzQ -----END PGP SIGNATURE----- Every security advisory uses the following format: Each security advisory is signed by the PGP key of the Security Officer. The public key for the Security Officer can be verified at . The name of the security advisory always begins with FreeBSD-SA- (for FreeBSD Security Advisory), followed by the year in two digit format (14:), followed by the advisory number for that year (04.), followed by the name of the affected application or subsystem (bind). The advisory shown here is the fourth advisory for 2014 and it affects BIND. The Topic field summarizes the vulnerability. The Category refers to the affected part of the system which may be one of core, contrib, or ports. The core category means that the vulnerability affects a core component of the &os; operating system. The contrib category means that the vulnerability affects software included with &os;, such as BIND. The ports category indicates that the vulnerability affects software available through the Ports Collection. The Module field refers to the component location. In this example, the bind module is affected; therefore, this vulnerability affects an application installed with the operating system. The Announced field reflects the date the security advisory was published. This means that the security team has verified that the problem exists and that a patch has been committed to the &os; source code repository. The Credits field gives credit to the individual or organization who noticed the vulnerability and reported it. The Affects field explains which releases of &os; are affected by this vulnerability. The Corrected field indicates the date, time, time offset, and releases that were corrected. The section in parentheses shows each branch for which the fix has been merged, and the version number of the corresponding release from that branch. The release identifier itself includes the version number and, if appropriate, the patch level. The patch level is the letter p followed by a number, indicating the sequence number of the patch, allowing users to track which patches have already been applied to the system. The CVE Name field lists the advisory number, if one exists, in the public cve.mitre.org security vulnerabilities database. The Background field provides a description of the affected module. The Problem Description field explains the vulnerability. This can include information about the flawed code and how the utility could be maliciously used. The Impact field describes what type of impact the problem could have on a system. The Workaround field indicates if a workaround is available to system administrators who cannot immediately patch the system . The Solution field provides the instructions for patching the affected system. This is a step by step tested and verified method for getting a system patched and working securely. The Correction Details field displays each affected Subversion branch with the revision number that contains the corrected code. The References field offers sources of additional information regarding the vulnerability. Process Accounting TomRhodesContributed by Process Accounting Process accounting is a security method in which an administrator may keep track of system resources used and their allocation among users, provide for system monitoring, and minimally track a user's commands. Process accounting has both positive and negative points. One of the positives is that an intrusion may be narrowed down to the point of entry. A negative is the amount of logs generated by process accounting, and the disk space they may require. This section walks an administrator through the basics of process accounting. If more fine-grained accounting is needed, refer to . Enabling and Utilizing Process Accounting Before using process accounting, it must be enabled using the following commands: &prompt.root; touch /var/account/acct &prompt.root; chmod 600 /var/account/acct &prompt.root; accton /var/account/acct &prompt.root; echo 'accounting_enable="YES"' >> /etc/rc.conf Once enabled, accounting will begin to track information such as CPU statistics and executed commands. All accounting logs are in a non-human readable format which can be viewed using sa. If issued without any options, sa prints information relating to the number of per-user calls, the total elapsed time in minutes, total CPU and user time in minutes, and the average number of I/O operations. Refer to &man.sa.8; for the list of available options which control the output. To display the commands issued by users, use lastcomm. For example, this command prints out all usage of ls by trhodes on the ttyp1 terminal: &prompt.root; lastcomm ls trhodes ttyp1 Many other useful options exist and are explained in &man.lastcomm.1;, &man.acct.5;, and &man.sa.8;. Resource Limits TomRhodesContributed by Resource limits &os; provides several methods for an administrator to limit the amount of system resources an individual may use. Disk quotas limit the amount of disk space available to users. Quotas are discussed in . quotas limiting users quotas disk quotas Limits to other resources, such as CPU and memory, can be set using either a flat file or a command to configure a resource limits database. The traditional method defines login classes by editing /etc/login.conf. While this method is still supported, any changes require a multi-step process of editing this file, rebuilding the resource database, making necessary changes to /etc/master.passwd, and rebuilding the password database. This can become time consuming, depending upon the number of users to configure. Beginning with &os; 9.0-RELEASE, rctl can be used to provide a more fine-grained method for controlling resource limits. This command supports more than user limits as it can also be used to set resource constraints on processes and jails. This section demonstrates both methods for controlling resources, beginning with the traditional method. Configuring Login Classes limiting users accounts limiting /etc/login.conf In the traditional method, login classes and the resource limits to apply to a login class are defined in /etc/login.conf. Each user account can be assigned to a login class, where default is the default login class. Each login class has a set of login capabilities associated with it. A login capability is a name=value pair, where name is a well-known identifier and value is an arbitrary string which is processed accordingly depending on the name. Whenever /etc/login.conf is edited, the /etc/login.conf.db must be updated by executing the following command: &prompt.root; cap_mkdb /etc/login.conf Resource limits differ from the default login capabilities in two ways. First, for every limit, there is a soft and hard limit. A soft limit may be adjusted by the user or application, but may not be set higher than the hard limit. The hard limit may be lowered by the user, but can only be raised by the superuser. Second, most resource limits apply per process to a specific user. lists the most commonly used resource limits. All of the available resource limits and capabilities are described in detail in &man.login.conf.5;. limiting users coredumpsize limiting users cputime limiting users filesize limiting users maxproc limiting users memorylocked limiting users memoryuse limiting users openfiles limiting users sbsize limiting users stacksize Login Class Resource Limits Resource Limit Description coredumpsize The limit on the size of a core file generated by a program is subordinate to other limits on disk usage, such as filesize or disk quotas. This limit is often used as a less severe method of controlling disk space consumption. Since users do not generate core files and often do not delete them, this setting may save them from running out of disk space should a large program crash. cputime The maximum amount of CPU time a user's process may consume. Offending processes will be killed by the kernel. This is a limit on CPU time consumed, not the percentage of the CPU as displayed in some of the fields generated by top and ps. filesize The maximum size of a file the user may own. Unlike disk quotas (), this limit is enforced on individual files, not the set of all files a user owns. maxproc The maximum number of foreground and background processes a user can run. This limit may not be larger than the system limit specified by kern.maxproc. Setting this limit too small may hinder a user's productivity as some tasks, such as compiling a large program, start lots of processes. memorylocked The maximum amount of memory a process may request to be locked into main memory using &man.mlock.2;. Some system-critical programs, such as &man.amd.8;, lock into main memory so that if the system begins to swap, they do not contribute to disk thrashing. memoryuse The maximum amount of memory a process may consume at any given time. It includes both core memory and swap usage. This is not a catch-all limit for restricting memory consumption, but is a good start. openfiles The maximum number of files a process may have open. In &os;, files are used to represent sockets and IPC channels, so be careful not to set this too low. The system-wide limit for this is defined by kern.maxfiles. sbsize The limit on the amount of network memory a user may consume. This can be generally used to limit network communications. stacksize The maximum size of a process stack. This alone is not sufficient to limit the amount of memory a program may use, so it should be used in conjunction with other limits.
There are a few other things to remember when setting resource limits: Processes started at system startup by /etc/rc are assigned to the daemon login class. Although the default /etc/login.conf is a good source of reasonable values for most limits, they may not be appropriate for every system. Setting a limit too high may open the system up to abuse, while setting it too low may put a strain on productivity. &xorg; takes a lot of resources and encourages users to run more programs simultaneously. Many limits apply to individual processes, not the user as a whole. For example, setting openfiles to 50 means that each process the user runs may open up to 50 files. The total amount of files a user may open is the value of openfiles multiplied by the value of maxproc. This also applies to memory consumption. For further information on resource limits and login classes and capabilities in general, refer to &man.cap.mkdb.1;, &man.getrlimit.2;, and &man.login.conf.5;. Enabling and Configuring Resource Limits As of &os; 10.2, rctl support is built into the kernel. Previous supported releases will need to be recompiled using the instructions in . Add these lines to either GENERIC or a custom kernel configuration file, then rebuild the kernel: options RACCT options RCTL Once the system has rebooted into the new kernel, rctl may be used to set rules for the system. Rule syntax is controlled through the use of a subject, subject-id, resource, and action, as seen in this example rule: user:trhodes:maxproc:deny=10/user In this rule, the subject is user, the subject-id is trhodes, the resource, maxproc, is the maximum number of processes, and the action is deny, which blocks any new processes from being created. This means that the user, trhodes, will be constrained to no greater than 10 processes. Other possible actions include logging to the console, passing a notification to &man.devd.8;, or sending a sigterm to the process. Some care must be taken when adding rules. Since this user is constrained to 10 processes, this example will prevent the user from performing other tasks after logging in and executing a screen session. Once a resource limit has been hit, an error will be printed, as in this example: &prompt.user; man test /usr/bin/man: Cannot fork: Resource temporarily unavailable eval: Cannot fork: Resource temporarily unavailable As another example, a jail can be prevented from exceeding a memory limit. This rule could be written as: &prompt.root; rctl -a jail:httpd:memoryuse:deny=2G/jail Rules will persist across reboots if they have been added to /etc/rctl.conf. The format is a rule, without the preceding command. For example, the previous rule could be added as: # Block jail from using more than 2G memory: jail:httpd:memoryuse:deny=2G/jail To remove a rule, use rctl to remove it from the list: &prompt.root; rctl -r user:trhodes:maxproc:deny=10/user A method for removing all rules is documented in &man.rctl.8;. However, if removing all rules for a single user is required, this command may be issued: &prompt.root; rctl -r user:trhodes Many other resources exist which can be used to exert additional control over various subjects. See &man.rctl.8; to learn about them. Shared Administration with Sudo TomRhodesContributed by Security Sudo System administrators often need the ability to grant enhanced permissions to users so they may perform privileged tasks. The idea that team members are provided access to a &os; system to perform their specific tasks opens up unique challenges to every administrator. These team members only need a subset of access beyond normal end user levels; however, they almost always tell management they are unable to perform their tasks without superuser access. Thankfully, there is no reason to provide such access to end users because tools exist to manage this exact requirement. Up to this point, the security chapter has covered permitting access to authorized users and attempting to prevent unauthorized access. Another problem arises once authorized users have access to the system resources. In many cases, some users may need access to application startup scripts, or a team of administrators need to maintain the system. Traditionally, the standard users and groups, file permissions, and even the &man.su.1; command would manage this access. And as applications required more access, as more users needed to use system resources, a better solution was required. The most used application is currently Sudo. Sudo allows administrators to configure more rigid access to system commands and provide for some advanced logging features. As a tool, it is available from the Ports Collection as security/sudo or by use of the &man.pkg.8; utility. To use the &man.pkg.8; tool: &prompt.root; pkg install sudo After the installation is complete, the installed visudo will open the configuration file with a text editor. Using visudo is highly recommended as it comes with a built in syntax checker to verify there are no errors before the file is saved. The configuration file is made up of several small sections which allow for extensive configuration. In the following example, web application maintainer, user1, needs to start, stop, and restart the web application known as webservice. To grant this user permission to perform these tasks, add this line to the end of /usr/local/etc/sudoers: user1 ALL=(ALL) /usr/sbin/service webservice * The user may now start webservice using this command: &prompt.user; sudo /usr/sbin/service webservice start While this configuration allows a single user access to the webservice service; however, in most organizations, there is an entire web team in charge of managing the service. A single line can also give access to an entire group. These steps will create a web group, add a user to this group, and allow all members of the group to manage the service: &prompt.root; pw groupadd -g 6001 -n webteam Using the same &man.pw.8; command, the user is added to the webteam group: &prompt.root; pw groupmod -m user1 -n webteam Finally, this line in /usr/local/etc/sudoers allows any member of the webteam group to manage webservice: %webteam ALL=(ALL) /usr/sbin/service webservice * Unlike &man.su.1;, Sudo only requires the end user password. This adds an advantage where users will not need shared passwords, a finding in most security audits and just bad all the way around. Users permitted to run applications with Sudo only enter their own passwords. This is more secure and gives better control than &man.su.1;, where the root password is entered and the user acquires all root permissions. Most organizations are moving or have moved toward a two factor authentication model. In these cases, the user may not have a password to enter. Sudo provides for these cases with the NOPASSWD variable. Adding it to the configuration above will allow all members of the webteam group to manage the service without the password requirement: %webteam ALL=(ALL) NOPASSWD: /usr/sbin/service webservice * Logging Output An advantage to implementing Sudo is the ability to enable session logging. Using the built in log mechanisms and the included sudoreplay command, all commands initiated through Sudo are logged for later verification. To enable this feature, add a default log directory entry, this example uses a user variable. Several other log filename conventions exist, consult the manual page for sudoreplay for additional information. Defaults iolog_dir=/var/log/sudo-io/%{user} This directory will be created automatically after the logging is configured. It is best to let the system create directory with default permissions just to be safe. In addition, this entry will also log administrators who use the sudoreplay command. To change this behavior, read and uncomment the logging options inside sudoers. Once this directive has been added to the sudoers file, any user configuration can be updated with the request to log access. In the example shown, the updated webteam entry would have the following additional changes: %webteam ALL=(ALL) NOPASSWD: LOG_INPUT: LOG_OUTPUT: /usr/sbin/service webservice * From this point on, all webteam members altering the status of the webservice application will be logged. The list of previous and current sessions can be displayed with: &prompt.root; sudoreplay -l In the output, to replay a specific session, search for the TSID= entry, and pass that to sudoreplay with no other options to replay the session at normal speed. For example: &prompt.root; sudoreplay user1/00/00/02 While sessions are logged, any administrator is able to remove sessions and leave only a question of why they had done so. It is worthwhile to add a daily check through an intrusion detection system (IDS) or similar software so that other administrators are alerted to manual alterations. The sudoreplay is extremely extendable. Consult the documentation for more information. Index: head/en_US.ISO8859-1/books/handbook/virtualization/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/virtualization/chapter.xml (revision 49530) +++ head/en_US.ISO8859-1/books/handbook/virtualization/chapter.xml (revision 49531) @@ -1,1316 +1,1316 @@ Virtualization Murray Stokely Contributed by Allan Jude bhyve section by 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 &os; on an &intel;-based &apple; &mac; computer. How to install &os; on µsoft.windows; with Virtual PC. How to install &os; as a guest in bhyve. How to tune a &os; system for best performance under virtualization. Before reading this chapter, you should: Understand the basics of &unix; and &os;. Know how to install &os;. Know how to set up a network connection. Know how to install additional third-party software. &os; as a Guest on <application>Parallels</application> for &macos; X Parallels Desktop for &mac; is a commercial software product available for &intel; based &apple; &mac; computers running &macos; 10.4.6 or higher. &os; is a fully supported guest operating system. Once Parallels has been installed on &macos; X, the user must configure a virtual machine and then install the desired guest operating system. Installing &os; on Parallels/&macos; X The first step in installing &os; on Parallels is to create a new virtual machine for installing &os;. Select &os; as the Guest OS Type when prompted: Choose a reasonable amount of disk and memory depending on the plans for this virtual &os; instance. 4GB of disk space and 512MB of RAM work well for most uses of &os; under Parallels: Select the type of networking and a network interface: Save and finish the configuration: After the &os; virtual machine has been created, &os; can be installed on it. This is best done with an official &os; CD/DVD or with an ISO image downloaded from an official FTP site. Copy the appropriate ISO image to the local &mac; filesystem or insert a CD/DVD in the &mac;'s CD-ROM drive. Click on the disc icon in the bottom right corner of the &os; 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. Once this association with the CD-ROM source has been made, reboot the &os; virtual machine by clicking the reboot icon. Parallels will reboot with a special BIOS that first checks if there is a CD-ROM. In this case it will find the &os; installation media and begin a normal &os; installation. Perform the installation, but do not attempt to configure &xorg; at this time. When the installation is finished, reboot into the newly installed &os; virtual machine. Configuring &os; on - <application>Parallels</application> + Parallels After &os; has been successfully installed on &macos; X with Parallels, there are a number of configuration steps that can be taken to optimize the system for virtualized operation. Set Boot Loader Variables The most important step is to reduce the tunable to reduce the CPU utilization of &os; under the Parallels environment. This is accomplished by adding the following line to /boot/loader.conf: kern.hz=100 Without this setting, an idle &os; Parallels guest will use roughly 15% of the CPU of a single processor &imac;. 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;. This can be accomplished by adding ifconfig_ed0="DHCP" to /etc/rc.conf. More advanced networking setups are described in . &os; as a Guest on <application>Virtual PC</application> for &windows; Virtual PC for &windows; is a µsoft; software product available for free download. See this website for the system requirements. Once Virtual PC has been installed on µsoft.windows;, the user can configure a virtual machine and then install the desired guest operating system. Installing &os; on <application>Virtual PC</application> The first step in installing &os; on Virtual PC is to create a new virtual machine for installing &os;. Select Create a virtual machine when prompted: Select Other as the Operating system when prompted: Then, choose a reasonable amount of disk and memory depending on the plans for this virtual &os; instance. 4GB of disk space and 512MB of RAM work well for most uses of &os; under Virtual PC: Save and finish the configuration: Select the &os; virtual machine and click Settings, then set the type of networking and a network interface: After the &os; virtual machine has been created, &os; can be installed on it. This is best done with an official &os; CD/DVD or with an ISO image downloaded from an official FTP site. Copy the appropriate ISO image to the local &windows; filesystem or insert a CD/DVD in the CD drive, then double click on the &os; virtual machine to boot. Then, click CD and choose 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. Once this association with the CD-ROM source has been made, reboot the &os; virtual machine by clicking Action and Reset. Virtual PC will reboot with a special BIOS that first checks for a CD-ROM. In this case it will find the &os; installation media and begin a normal &os; installation. Continue with the installation, but do not attempt to configure &xorg; at this time. When the installation is finished, remember to eject the CD/DVD or release the ISO image. Finally, reboot into the newly installed &os; virtual machine. Configuring &os; on <application>Virtual PC</application> After &os; has been successfully installed on µsoft.windows; with Virtual PC, there are a number of configuration steps that can be taken to optimize the system for virtualized operation. Set Boot Loader Variables The most important step is to reduce the tunable to reduce the CPU utilization of &os; under the Virtual PC environment. This is accomplished by adding the following line to /boot/loader.conf: kern.hz=100 Without this setting, an idle &os; 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 µsoft.windows; host. This can be accomplished by adding ifconfig_de0="DHCP" to /etc/rc.conf. More advanced networking setups are described in . &os; as a Guest on <application>VMware Fusion</application> for &macos; VMware Fusion for &mac; is a commercial software product available for &intel; based &apple; &mac; computers running &macos; 10.4.9 or higher. &os; is a fully supported guest operating system. Once VMware Fusion has been installed on &macos; X, the user can configure a virtual machine and then install the desired guest operating system. Installing &os; on <application>VMware Fusion</application> The first step is to start VMware Fusion which will load the Virtual Machine Library. Click New to create the virtual machine: This will load the New Virtual Machine Assistant. Click Continue to proceed: Select Other as the Operating System and either &os; or &os; 64-bit, as the Version when prompted: Choose the name of the virtual machine and the directory where it should be saved: Choose the size of the Virtual Hard Disk for the virtual machine: Choose the method to install the virtual machine, either from an ISO image or from a CD/DVD: Click Finish and the virtual machine will boot: Install &os; as usual: Once the install is complete, the settings of the virtual machine can be modified, such as memory usage: The System Hardware settings of the virtual machine cannot be modified while the virtual machine is running. The number of CPUs the virtual machine will have access to: The status of the CD-ROM device. Normally the CD/DVD/ISO is disconnected from the virtual machine when it is no longer needed. 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 Connect directly to the physical network (Bridged). Otherwise, 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. After modifying the settings, boot the newly installed &os; virtual machine. Configuring &os; on <application>VMware Fusion</application> After &os; has been successfully installed on &macos; X with VMware Fusion, there are a number of configuration steps that can be taken to optimize the system for virtualized operation. Set Boot Loader Variables The most important step is to reduce the tunable to reduce the CPU utilization of &os; under the VMware Fusion environment. This is accomplished by adding the following line to /boot/loader.conf: kern.hz=100 Without this setting, an idle &os; VMware Fusion guest will use roughly 15% of the CPU of a single processor &imac;. 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;. This can be accomplished by adding ifconfig_em0="DHCP" to /etc/rc.conf. More advanced networking setups are described in . &os; as a Guest on &virtualbox; &os; works well as a guest in &virtualbox;. The virtualization software is available for most common operating systems, including &os; itself. The &virtualbox; guest additions provide support for: Clipboard sharing. Mouse pointer integration. Host time synchronization. Window scaling. Seamless mode. These commands are run in the &os; guest. First, install the emulators/virtualbox-ose-additions package or port in the &os; guest. This will install the port: &prompt.root; cd /usr/ports/emulators/virtualbox-ose-additions && make install clean Add these lines to /etc/rc.conf: vboxguest_enable="YES" vboxservice_enable="YES" If &man.ntpd.8; or &man.ntpdate.8; is used, disable host time synchronization: vboxservice_flags="--disable-timesync" Xorg will automatically recognize the vboxvideo driver. It can also be manually entered in /etc/X11/xorg.conf: 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 /etc/X11/xorg.conf: Section "InputDevice" Identifier "Mouse0" Driver "vboxmouse" EndSection HAL users should create the following /usr/local/etc/hal/fdi/policy/90-vboxguest.fdi or copy it from /usr/local/share/hal/fdi/policy/10osvendor/90-vboxguest.fdi: <?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> &os; as a Host with <application>VirtualBox</application> &virtualbox; is an actively developed, complete virtualization package, that is available for most operating systems including &windows;, &macos;, &linux; and &os;. It is equally capable of running &windows; or &unix;-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 Downloads page of the &virtualbox; wiki. Currently, these extensions are not available for &os;. Installing &virtualbox; &virtualbox; is available as a &os; package or port in emulators/virtualbox-ose. The port can be installed using these commands: &prompt.root; cd /usr/ports/emulators/virtualbox-ose &prompt.root; 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; guests. The guest additions are available in the Devices menu, after the installation of the guest is finished. A few configuration changes are needed before &virtualbox; is started for the first time. The port installs a kernel module in /boot/modules which must be loaded into the running kernel: &prompt.root; kldload vboxdrv To ensure the module is always loaded after a reboot, add this line to /boot/loader.conf: vboxdrv_load="YES" To use the kernel modules that allow bridged or host-only networking, add this line to /etc/rc.conf and reboot the computer: vboxnet_enable="YES" The vboxusers group is created during installation of &virtualbox;. All users that need access to &virtualbox; will have to be added as members of this group. pw can be used to add new members: &prompt.root; pw groupmod vboxusers -m yourusername The default permissions for /dev/vboxnetctl are restrictive and need to be changed for bridged networking: &prompt.root; chown root:vboxusers /dev/vboxnetctl &prompt.root; chmod 0660 /dev/vboxnetctl To make this permissions change permanent, add these lines to /etc/devfs.conf: own vboxnetctl root:vboxusers perm vboxnetctl 0660 To launch &virtualbox;, type from a &xorg; session: &prompt.user; VirtualBox For more information on configuring and using &virtualbox;, refer to the official website. For &os;-specific information and troubleshooting instructions, refer to the relevant page in the &os; wiki. &virtualbox; USB Support In order to be able to read and write to USB devices, users need to be members of operator: &prompt.root; pw groupmod operator -m jerry Then, add the following to /etc/devfs.rules, or create this file if it does not exist yet: [system=10] add path 'usb/*' mode 0660 group operator To load these new rules, add the following to /etc/rc.conf: devfs_system_ruleset="system" Then, restart devfs: &prompt.root; service devfs restart USB can now be enabled in the guest operating system. USB devices should be visible in the &virtualbox; preferences. &virtualbox; Host <acronym>DVD</acronym>/<acronym>CD</acronym> Access Access to the host DVD/CD drives from guests is achieved through the sharing of the physical drives. Within &virtualbox;, this is set up from the Storage window in the Settings of the virtual machine. If needed, create an empty IDE CD/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; DVD/CD functions to work, so enable it in /etc/rc.conf and start it if it is not already running: hald_enable="YES" &prompt.root; service hald start In order for users to be able to use &virtualbox; DVD/CD functions, they need access to /dev/xpt0, /dev/cdN, and /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 /etc/devfs.conf: perm cd* 0660 perm xpt0 0660 perm pass* 0660 &prompt.root; service devfs restart &os; as a Host with <application>bhyve</application> The bhyve BSD-licensed hypervisor became part of the base system with &os; 10.0-RELEASE. This hypervisor supports a number of guests, including &os;, OpenBSD, and many &linux; distributions. Currently, bhyve only supports a 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; Extended Page Tables (EPT) or &amd; Rapid Virtualization Indexing (RVI) or Nested Page Tables (NPT). Hosting &linux; guests or &os; guests with more than one vCPU requires VMX unrestricted mode support (UG). Most newer processors, specifically the &intel; &core; i3/i5/i7 and &intel; &xeon; E3/E5/E7, support these features. UG support was introduced with Intel's Westmere micro-architecture. For a complete list of &intel; processors that support EPT, refer to . RVI is found on the third generation and later of the &amd.opteron; (Barcelona) processors. The easiest way to tell if a processor supports bhyve is to run dmesg or look in /var/run/dmesg.boot for the POPCNT processor feature flag on the Features2 line for &amd; processors or EPT and UG on the VT-x line for &intel; processors. Preparing the Host The first step to creating a virtual machine in bhyve is configuring the host system. First, load the bhyve kernel module: &prompt.root; kldload vmm Then, create a 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 tap interface and the physical interface as members. In this example, the physical interface is igb0: &prompt.root; ifconfig tap0 create &prompt.root; sysctl net.link.tap.up_on_open=1 net.link.tap.up_on_open: 0 -> 1 &prompt.root; ifconfig bridge0 create &prompt.root; ifconfig bridge0 addm igb0 addm tap0 &prompt.root; ifconfig bridge0 up 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: &prompt.root; truncate -s 16G guest.img Download an installation image of &os; to install: &prompt.root; fetch ftp://ftp.freebsd.org/pub/FreeBSD/releases/ISO-IMAGES/10.3/FreeBSD-10.3-RELEASE-amd64-bootonly.iso FreeBSD-10.3-RELEASE-amd64-bootonly.iso 100% of 230 MB 570 kBps 06m17s &os; 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: controls the number of virtual CPUs, limits the amount of memory available to the guest, defines which tap device to use, indicates which disk image to use, tells bhyve to boot from the CD image instead of the disk, and 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: &prompt.root; sh /usr/share/examples/bhyve/vmrun.sh -c 4 -m 1024M -t tap0 -d guest.img -i -I FreeBSD-10.3-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 Yes. A small change needs to be made to make the system start with a serial console. Edit /etc/ttys and replace the existing ttyu0 line with: ttyu0 "/usr/libexec/getty 3wire" xterm on secure Beginning with &os; 9.3-RELEASE and 10.1-RELEASE the console is configured automatically. Reboot the virtual machine. While rebooting the virtual machine causes bhyve to exit, the 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: &prompt.root; sh /usr/share/examples/bhyve/vmrun.sh -c 4 -m 1024M -t tap0 -d guest.img guestname Creating a &linux; Guest In order to boot operating systems other than &os;, the sysutils/grub2-bhyve port must be first installed. Next, create a file to use as the virtual disk for the guest machine: &prompt.root; 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; kernel is loaded with sysutils/grub2-bhyve. Create a device.map that grub will use to map the virtual devices to the files on the host system: (hd0) ./linux.img (cd0) ./somelinux.iso Use sysutils/grub2-bhyve to load the &linux; kernel from the ISO image: &prompt.root; grub-bhyve -m device.map -r cd0 -M 1024M linuxguest This will start grub. If the installation CD contains a grub.cfg, a menu will be displayed. If not, the vmlinuz and initrd files must be located and loaded manually: 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; kernel is loaded, the guest can be started: &prompt.root; bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap1 -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: &prompt.root; bhyvectl --destroy --vm=linuxguest Now the guest can be started directly from the virtual disk. Load the kernel: &prompt.root; 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: &prompt.root; bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap1 \ -s 3:0,virtio-blk,./linux.img -l com1,stdio -c 4 -m 1024M linuxguest &linux; 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: &prompt.root; bhyvectl --destroy --vm=linuxguest Using <acronym>ZFS</acronym> with <application>bhyve</application> 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: &prompt.root; zfs create -V16G -o volmode=dev zroot/linuxdisk0 When starting the VM, specify the ZFS volume as the disk drive: &prompt.root; bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap1 -s3:0,virtio-blk,/dev/zvol/zroot/linuxdisk0 \ -l com1,stdio -c 4 -m 1024M linuxguest Virtual Machine Consoles It is advantageous to wrap the bhyve console in a session management tool such as sysutils/tmux or 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 nmdm kernel module and replace with . The /dev/nmdm devices are created automatically as needed, where each is a pair, corresponding to the two ends of the null modem cable (/dev/nmdm0A and /dev/nmdm0B). See &man.nmdm.4; for more information. &prompt.root; kldload nmdm &prompt.root; bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,tap1 -s 3:0,virtio-blk,./linux.img \ -l com1,/dev/nmdm0A -c 4 -m 1024M linuxguest &prompt.root; cu -l /dev/nmdm0B Connected Ubuntu 13.10 handbook ttyS0 handbook login: Managing Virtual Machines A device node is created in /dev/vmm for each virtual machine. This allows the administrator to easily see a list of the running virtual machines: &prompt.root; 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: &prompt.root; bhyvectl --destroy --vm=guestname 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: <filename>/etc/sysctl.conf</filename> net.link.tap.up_on_open=1 <filename>/boot/loader.conf</filename> vmm_load="YES" nmdm_load="YES" if_bridge_load="YES" if_tap_load="YES" <filename>/etc/rc.conf</filename> cloned_interfaces="bridge0 tap0" ifconfig_bridge0="addm igb0 addm tap0"