Index: head/en_US.ISO8859-1/books/faq/book.xml =================================================================== --- head/en_US.ISO8859-1/books/faq/book.xml (revision 51389) +++ head/en_US.ISO8859-1/books/faq/book.xml (revision 51390) @@ -1,7469 +1,7471 @@ 12-CURRENT"> X"> head/"> X"> 11-STABLE"> stable/11/"> X"> 10-STABLE"> stable/10/"> ]> Frequently Asked Questions for &os; &rel2.relx; and &rel.relx; The &os; Documentation Project 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 The &os; Documentation Project &legalnotice; &tm-attrib.freebsd; &tm-attrib.adobe; &tm-attrib.ibm; &tm-attrib.ieee; &tm-attrib.intel; &tm-attrib.linux; &tm-attrib.microsoft; &tm-attrib.netbsd; &tm-attrib.opengroup; &tm-attrib.sgi; &tm-attrib.sun; &tm-attrib.general; $FreeBSD$ This is the Frequently Asked Questions (FAQ) for &os; versions &rel2.relx; and &rel.relx;. Every effort has been made to make this FAQ as informative as possible; if you have any suggestions as to how it may be improved, send them to the &a.doc;. The latest version of this document is always available from the &os; website. It may also be downloaded as one large HTML file with HTTP or as a variety of other formats from the &os; FTP server. Introduction What is &os;? &os; is a modern operating system for desktops, laptops, servers, and embedded systems with support for a large number of platforms. It is based on U.C. Berkeley's 4.4BSD-Lite release, with some 4.4BSD-Lite2 enhancements. It is also based indirectly on William Jolitz's port of U.C. Berkeley's Net/2 to the &i386;, known as 386BSD, though very little of the 386BSD code remains. &os; is used by companies, Internet Service Providers, researchers, computer professionals, students and home users all over the world in their work, education and recreation. For more detailed information on &os;, refer to the &os; Handbook. What is the goal of the &os; Project? The goal of the &os; Project is to provide a stable and fast general purpose operating system that may be used for any purpose without strings attached. Does the &os; license have any restrictions? Yes. Those restrictions do not control how the code is used, but how to treat the &os; Project itself. The license itself is available at license and can be summarized like this: Do not claim that you wrote this. Do not sue us if it breaks. Do not remove or modify the license. Many of us have a significant investment in the project and would certainly not mind a little financial compensation now and then, but we definitely do not insist on it. We believe that our first and foremost mission is to provide code to any and all comers, and for whatever purpose, so that the code gets the widest possible use and provides the widest possible benefit. This, we believe, is one of the most fundamental goals of Free Software and one that we enthusiastically support. Code in our source tree which falls under the GNU General Public License (GPL) or GNU Library General Public License (LGPL) comes with slightly more strings attached, though at least on the side of enforced access rather than the usual opposite. Due to the additional complexities that can evolve in the commercial use of GPL software, we do, however, endeavor to replace such software with submissions under the more relaxed &os; license whenever possible. Can &os; replace my current operating system? For most people, yes. But this question is not quite that cut-and-dried. Most people do not actually use an operating system. They use applications. The applications are what really use the operating system. &os; is designed to provide a robust and full-featured environment for applications. It supports a wide variety of web browsers, office suites, email readers, graphics programs, programming environments, network servers, and much more. Most of these applications can be managed through the Ports Collection. If an application is only available on one operating system, that operating system cannot just be replaced. Chances are, there is a very similar application on &os;, however. As a solid office or Internet server or a reliable workstation, &os; will almost certainly do everything you need. Many computer users across the world, including both novices and experienced &unix; administrators, use &os; as their only desktop operating system. Users migrating to &os; from another &unix;-like environment will find &os; to be similar. &windows; and &macos; users may be interested in instead using TrueOS, a &os;-based desktop distribution. Non-&unix; users should expect to invest some additional time learning the &unix; way of doing things. This FAQ and the &os; Handbook are excellent places to start. Why is it called &os;? It may be used free of charge, even by commercial users. Full source for the operating system is freely available, and the minimum possible restrictions have been placed upon its use, distribution and incorporation into other work (commercial or non-commercial). Anyone who has an improvement or bug fix is free to submit their code and have it added to the source tree (subject to one or two obvious provisions). It is worth pointing out that the word free is being used in two ways here: one meaning at no cost and the other meaning do whatever you like. Apart from one or two things you cannot do with the &os; code, for example pretending you wrote it, you can really do whatever you like with it. What are the differences between &os; and NetBSD, OpenBSD, and other open source BSD operating systems? James Howard wrote a good explanation of the history and differences between the various projects, called The BSD Family Tree which goes a fair way to answering this question. Some of the information is out of date, but the history portion in particular remains accurate. Most of the BSDs share patches and code, even today. All of the BSDs have common ancestry. The design goals of &os; are described in , above. The design goals of the other most popular BSDs may be summarized as follows: OpenBSD aims for operating system security above all else. The OpenBSD team wrote &man.ssh.1; and &man.pf.4;, which have both been ported to &os;. NetBSD aims to be easily ported to other hardware platforms. DragonFly BSD is a fork of &os; 4.8 that has since developed many interesting features of its own, including the HAMMER file system and support for user-mode vkernels. What is the latest version of &os;? At any point in the development of &os;, there can be multiple parallel branches. &rel.relx; releases are made from the &rel.stable; branch, and &rel2.relx; releases are made from the &rel2.stable; branch. Up until the release of 9.0, the &rel2.relx; series was the one known as -STABLE. However, as of &rel.head.relx;, the &rel2.relx; branch will be designated for an extended support status and receive only fixes for major problems, such as security-related fixes. Version &rel.current; is the latest release from the &rel.stable; branch; it was released in &rel.current.date;. Version &rel2.current; is the latest release from the &rel2.stable; branch; it was released in &rel2.current.date;. Releases are made every few months. While many people stay more up-to-date with the &os; sources (see the questions on &os.current; and &os.stable;) than that, doing so is more of a commitment, as the sources are a moving target. More information on &os; releases can be found on the Release Engineering page and in &man.release.7;. What is &os;-CURRENT? &os.current; is the development version of the operating system, which will in due course become the new &os.stable; branch. As such, it is really only of interest to developers working on the system and die-hard hobbyists. See the relevant section in the Handbook for details on running -CURRENT. Users not familiar with &os; should not use &os.current;. This branch sometimes evolves quite quickly and due to mistake can be un-buildable at times. People that use &os.current; are expected to be able to analyze, debug, and report problems. &os; snapshot releases are made based on the current state of the -CURRENT and -STABLE branches. The goals behind each snapshot release are: To test the latest version of the installation software. To give people who would like to run -CURRENT or -STABLE but who do not have the time or bandwidth to follow it on a day-to-day basis an easy way of bootstrapping it onto their systems. To preserve a fixed reference point for the code in question, just in case we break something really badly later. (Although Subversion normally prevents anything horrible like this happening.) To ensure that all new features and fixes in need of testing have the greatest possible number of potential testers. No claims are made that any -CURRENT snapshot can be considered production quality for any purpose. If a stable and fully tested system is needed, stick to full releases. Snapshot releases are directly available from snapshot. Official snapshots are generated on a regular basis for all actively developed branches. What is the &os;-STABLE concept? Back when &os; 2.0.5 was released, &os; development branched in two. One branch was named -STABLE, one -CURRENT. &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. However, at any given time, the sources for &os;-STABLE may or may not be suitable for general use, as it may uncover bugs and corner cases that were not yet found in &os;-CURRENT. Users who do not have the resources to perform testing should instead run the most recent release of &os;. &os;-CURRENT, on the other hand, has been one unbroken line since 2.0 was released, leading towards &rel.current;-RELEASE and beyond. For more detailed information on branches see &os; Release Engineering: Creating the Release Branch, the status of the branches and the upcoming release schedule can be found on the Release Engineering Information page. &rel.current;-STABLE is the actively developed -STABLE branch. The latest release on the &rel.current;-STABLE branch is &rel.current;-RELEASE, which was released in &rel.current.date;. The &rel.head; branch is the actively developed -CURRENT branch toward the next generation of &os;. See What is &os;-CURRENT? for more information on this branch. When are &os; releases made? The &a.re; releases a new major version of &os; about every 18 months and a new minor version about every 8 months, on average. Release dates are announced well in advance, so that the people working on the system know when their projects need to be finished and tested. A testing period precedes each release, to ensure that the addition of new features does not compromise the stability of the release. Many users regard this caution as one of the best things about &os;, even though waiting for all the latest goodies to reach -STABLE can be a little frustrating. More information on the release engineering process (including a schedule of upcoming releases) can be found on the release engineering pages on the &os; Web site. For people who need or want a little more excitement, binary snapshots are made weekly as discussed above. Who is responsible for &os;? The key decisions concerning the &os; project, such as the overall direction of the project and who is allowed to add code to the source tree, are made by a core team of 9 people. There is a much larger team of more than 350 committers who are authorized to make changes directly to the &os; source tree. However, most non-trivial changes are discussed in advance in the mailing lists, and there are no restrictions on who may take part in the discussion. Where can I get &os;? Every significant release of &os; is available via anonymous FTP from the &os; FTP site: The latest &rel.stable; release, &rel.current;-RELEASE can be found in the &rel.current;-RELEASE directory. Snapshot releases are made monthly for the -CURRENT and -STABLE branch, these being of service purely to bleeding-edge testers and developers. The latest &rel2.stable; release, &rel2.current;-RELEASE can be found in the &rel2.current;-RELEASE directory. Information about obtaining &os; on CD, DVD, and other media can be found in the Handbook. How do I access the Problem Report database? The Problem Report database of all user change requests may be queried by using our web-based PR query interface. The web-based problem report submission interface can be used to submit problem reports through a web browser. Before submitting a problem report, read Writing &os; Problem Reports, an article on how to write good problem reports. Documentation and Support What good books are there about &os;? The project produces a wide range of documentation, available online from this link: https://www.FreeBSD.org/docs.html. In addition, the Bibliography at the end of this FAQ, and the one in the Handbook reference other recommended books. Is the documentation available in other formats, such as plain text (ASCII), or &postscript;? Yes. The documentation is available in a number of different formats and compression schemes on the &os; FTP site, in the /pub/FreeBSD/doc/ directory. The documentation is categorized in a number of different ways. These include: The document's name, such as faq, or handbook. The document's language and encoding. These are based on the locale names found under /usr/share/locale on a &os; system. The current languages and encodings are as follows: Name Meaning en_US.ISO8859-1 English (United States) bn_BD.ISO10646-1 Bengali or Bangla (Bangladesh) da_DK.ISO8859-1 Danish (Denmark) de_DE.ISO8859-1 German (Germany) el_GR.ISO8859-7 Greek (Greece) es_ES.ISO8859-1 Spanish (Spain) fr_FR.ISO8859-1 French (France) hu_HU.ISO8859-2 Hungarian (Hungary) it_IT.ISO8859-15 Italian (Italy) ja_JP.eucJP Japanese (Japan, EUC encoding) mn_MN.UTF-8 Mongolian (Mongolia, UTF-8 encoding) nl_NL.ISO8859-1 Dutch (Netherlands) no_NO.ISO8859-1 Norwegian (Norway) pl_PL.ISO8859-2 Polish (Poland) pt_BR.ISO8859-1 Portuguese (Brazil) ru_RU.KOI8-R Russian (Russia, KOI8-R encoding) sr_YU.ISO8859-2 Serbian (Serbia) tr_TR.ISO8859-9 Turkish (Turkey) zh_CN.UTF-8 Simplified Chinese (China, UTF-8 encoding) zh_TW.UTF-8 Traditional Chinese (Taiwan, UTF-8 encoding) Some documents may not be available in all languages. The document's format. We produce the documentation in a number of different output formats. Each format has its own advantages and disadvantages. Some formats are better suited for online reading, while others are meant to be aesthetically pleasing when printed on paper. Having the documentation available in any of these formats ensures that our readers will be able to read the parts they are interested in, either on their monitor, or on paper after printing the documents. The currently available formats are: Format Meaning html-split A collection of small, linked, HTML files. html One large HTML file containing the entire document pdf Adobe's Portable Document Format ps &postscript; rtf µsoft;'s Rich Text Format txt Plain text Page numbers are not automatically updated when loading Rich Text Format into Word. Press CtrlA, CtrlEnd, F9 after loading the document, to update the page numbers. The compression and packaging scheme. Where the format is html-split, the files are bundled up using &man.tar.1;. The resulting .tar file is then compressed using the compression schemes detailed in the next point. All the other formats generate one file. For example, article.pdf, book.html, and so on. These files are then compressed using either the zip or bz2 compression schemes. &man.tar.1; can be used to uncompress these files. So the &postscript; version of the Handbook, compressed using bzip2 will be stored in a file called book.ps.bz2 in the handbook/ directory. After choosing the format and compression mechanism, download the compressed files, uncompress them, and then copy the appropriate documents into place. For example, the split HTML version of the FAQ, compressed using &man.bzip2.1;, can be found in doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2 To download and uncompress that file, type: &prompt.root; fetch https://download.freebsd.org/ftp/doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2 &prompt.root; tar xvf book.html-split.tar.bz2 If the file is compressed, tar will automatically detect the appropriate format and decompress it correctly, resulting in a collection of .html files. The main one is called index.html, which will contain the table of contents, introductory material, and links to the other parts of the document. Where do I find info on the &os; mailing lists? What &os; news groups are available? Refer to the Handbook entry on mailing-lists and the Handbook entry on newsgroups. Are there &os; IRC (Internet Relay Chat) channels? Yes, most major IRC networks host a &os; chat channel: Channel #FreeBSDhelp on EFNet is a channel dedicated to helping &os; users. Channel #FreeBSD on Freenode is a general help channel with many users at any time. The conversations have been known to run off-topic for a while, but priority is given to users with &os; questions. Other users can help with the basics, referring to the Handbook whenever possible and providing links for learning more about a particular topic. This is primarily an English speaking channel, though it does have users from all over the world. Non-native English speakers should try to ask the question in English first and then relocate to ##freebsd-lang as appropriate. Channel #FreeBSD on DALNET is available at irc.dal.net in the US and irc.eu.dal.net in Europe. Channel #FreeBSD on UNDERNET is available at us.undernet.org in the US and eu.undernet.org in Europe. Since it is a help channel, be prepared to read the documents you are referred to. Channel #FreeBSD on RUSNET is a Russian language channel dedicated to helping &os; users. This is also good place for non-technical discussions. Channel #bsdchat on Freenode is a Traditional Chinese (UTF-8 encoding) language channel dedicated to helping &os; users. This is also good place for non-technical discussions. The &os; wiki has a good list of IRC channels. Each of these channels are distinct and are not connected to each other. Since their chat styles differ, try each to find one suited to your chat style. Are there any web based forums to discuss &os;? The official &os; forums are located at https://forums.FreeBSD.org/. Where can I get commercial &os; training and support? iXsystems, Inc., parent company of the &os; Mall, provides commercial &os; and TrueOS software support, in addition to &os; development and tuning solutions. BSD Certification Group, Inc. provides system administration certifications for DragonFly BSD, &os;, NetBSD, and OpenBSD. Refer to their site for more information. Any other organizations providing training and support should contact the Project to be listed here. Installation Nik Clayton
nik@FreeBSD.org
Which platform should I download? I have a 64 bit capable &intel; CPU, but I only see amd64. &arch.amd64; is the term &os; uses for 64-bit compatible x86 architectures (also known as "x86-64" or "x64"). Most modern computers should use &arch.amd64;. Older hardware should use &arch.i386;. When installing on a non-x86-compatible architecture, select the platform which best matches the hardware. Which file do I download to get &os;? On the Getting &os; page, select [iso] next to the architecture that matches the hardware. Any of the following can be used: file description disc1.iso Contains enough to install &os; and a minimal set of packages. dvd1.iso Similar to disc1.iso but with additional packages. memstick.img A bootable image sufficient for writing to a USB stick. bootonly.iso A minimal image that requires network access during installation to completely install &os;. Full instructions on this procedure and a little bit more about installation issues in general can be found in the Handbook entry on installing &os;. What do I do if the install image does not boot? This can be caused by not downloading the image in binary mode when using FTP. Some FTP clients default their transfer mode to ascii and attempt to change any end-of-line characters received to match the conventions used by the client's system. This will almost invariably corrupt the boot image. Check the SHA-256 checksum of the downloaded boot image: if it is not exactly that on the server, then the download process is suspect. When using a command line FTP client, type binary at the FTP command prompt after getting connected to the server and before starting the download of the image. Where are the instructions for installing &os;? Installation instructions can be found at Handbook entry on installing &os;. What are the minimum requirements to run &os;? &os; requires a 486 or better PC, 64 MB or more of RAM, and at least 1.1 GB of hard disk space. How can I make my own custom release or install disk? Customized &os; installation media can be created by building a custom release. Follow the instructions in the Release Engineering article. Can &windows; co-exist with &os;? If &windows; is installed first, then yes. &os;'s boot manager will then manage to boot &windows; and &os;. If &windows; is installed afterwards, it will overwrite the boot manager. If that happens, see the next section. Another operating system destroyed my Boot Manager. How do I get it back? This depends upon the boot manager. The &os; boot selection menu can be reinstalled using &man.boot0cfg.8;. For example, to restore the boot menu onto the disk ada0: &prompt.root; boot0cfg -B ada0 The non-interactive MBR bootloader can be installed using &man.gpart.8;: &prompt.root; gpart bootcode -b /boot/mbr ada0 For more complex situations, including GPT disks, see &man.gpart.8;. Do I need to install the source? In general, no. There is nothing in the base system which requires the presence of the source to operate. Some ports, like sysutils/lsof, will not build unless the source is installed. In particular, if the port builds a kernel module or directly operates on kernel structures, the source must be installed. Do I need to build a kernel? Usually not. The supplied GENERIC kernel contains the drivers an ordinary computer will need. &man.freebsd-update.8;, the &os; binary upgrade tool, cannot upgrade custom kernels, another reason to stick with the GENERIC kernel when possible. For computers with very limited RAM, such as embedded systems, it may be worthwhile to build a smaller custom kernel containing just the required drivers. Should I use DES, Blowfish, or MD5 passwords and how do I specify which form my users receive? &os; uses SHA512 by default. DES passwords are still available for backwards compatibility with operating systems that still use the less secure password format. &os; also supports the Blowfish and MD5 password formats. Which password format to use for new passwords is controlled by the passwd_format login capability in /etc/login.conf, which takes values of des, blf (if these are available) or md5. See the &man.login.conf.5; manual page for more information about login capabilities. What are the limits for FFS file systems? For FFS file systems, the largest file system is practically limited by the amount of memory required to &man.fsck.8; the file system. &man.fsck.8; requires one bit per fragment, which with the default fragment size of 4 KB equates to 32 MB of memory per TB of disk. This does mean that on architectures which limit userland processes to 2 GB (e.g., &i386;), the maximum &man.fsck.8;'able filesystem is ~60 TB. If there was not a &man.fsck.8; memory limit the maximum filesystem size would be 2 ^ 64 (blocks) * 32 KB => 16 Exa * 32 KB => 512 ZettaBytes. The maximum size of a single FFS file is approximately 2 PB with the default block size of 32 KB. Each 32 KB block can point to 4096 blocks. With triple indirect blocks, the calculation is 32 KB * 12 + 32 KB * 4096 + 32 KB * 4096^2 + 32 KB * 4096^3. Increasing the block size to 64 KB will increase the max file size by a factor of 16. Why do I get an error message, readin failed after compiling and booting a new kernel? The world and kernel are out of sync. This is not supported. Be sure to use make buildworld and make buildkernel to update the kernel. Boot the system by specifying the kernel directly at the second stage, pressing any key when the | shows up before loader is started. Is there a tool to perform post-installation configuration tasks? Yes. bsdconfig provides a nice interface to configure &os; post-installation. Hardware Compatibility General I want to get a piece of hardware for my &os; system. Which model/brand/type is best? This is discussed continually on the &os; mailing lists but is to be expected since hardware changes so quickly. Read through the Hardware Notes for &os; &rel.current; or &rel2.current; and search the mailing list archives before asking about the latest and greatest hardware. Chances are a discussion about that type of hardware took place just last week. Before purchasing a laptop, check the archives for &a.mobile; and &a.questions;, or possibly a specific mailing list for a particular hardware type. What are the limits for memory? Does &os; support more than 4 GB of memory (RAM)? More than 16 GB? More than 48 GB? &os; as an operating system generally supports as much physical memory (RAM) as the platform it is running on does. Keep in mind that different platforms have different limits for memory; for example &i386; without PAE supports at most 4 GB of memory (and usually less than that because of PCI address space) and &i386; with PAE supports at most 64 GB memory. As of &os; 10, AMD64 platforms support up to 4 TB of physical memory. Why does &os; report less than 4 GB memory when installed on an &i386; machine? The total address space on &i386; machines is 32-bit, meaning that at most 4 GB of memory is addressable (can be accessed). Furthermore, some addresses in this range are reserved by hardware for different purposes, for example for using and controlling PCI devices, for accessing video memory, and so on. Therefore, the total amount of memory usable by the operating system for its kernel and applications is limited to significantly less than 4 GB. Usually, 3.2 GB to 3.7 GB is the maximum usable physical memory in this configuration. To access more than 3.2 GB to 3.7 GB of installed memory (meaning up to 4 GB but also more than 4 GB), a special tweak called PAE must be used. PAE stands for Physical Address Extension and is a way for 32-bit x86 CPUs to address more than 4 GB of memory. It remaps the memory that would otherwise be overlaid by address reservations for hardware devices above the 4 GB range and uses it as additional physical memory (see &man.pae.4;). Using PAE has some drawbacks; this mode of memory access is a little bit slower than the normal (without PAE) mode and loadable modules (see &man.kld.4;) are not supported. This means all drivers must be compiled into the kernel. The most common way to enable PAE is to build a new kernel with the special ready-provided kernel configuration file called PAE, which is already configured to build a safe kernel. Note that some entries in this kernel configuration file are too conservative and some drivers marked as unready to be used with PAE are actually usable. A rule of thumb is that if the driver is usable on 64-bit architectures (like AMD64), it is also usable with PAE. When creating a custom kernel configuration file, PAE can be enabled by adding the following line: options PAE PAE is not much used nowadays because most new x86 hardware also supports running in 64-bit mode, known as AMD64 or &intel; 64. It has a much larger address space and does not need such tweaks. &os; supports AMD64 and it is recommended that this version of &os; be used instead of the &i386; version if 4 GB or more memory is required. Architectures and Processors Does &os; support architectures other than the x86? Yes. &os; divides support into multiple tiers. Tier 1 architectures, such as i386 or amd64; are fully supported. Tiers 2 and 3 are supported on a best-effort basis. A full explanation of the tier system is available in the Committer's Guide. A complete list of supported architectures can be found on the platforms page. Does &os; support Symmetric Multiprocessing (SMP)? &os; supports symmetric multi-processor (SMP) on all non-embedded platforms (e.g, &arch.i386;, &arch.amd64;, etc.). SMP is also supported in arm and MIPS kernels, although some CPUs may not support this. &os;'s SMP implementation uses fine-grained locking, and performance scales nearly linearly with number of CPUs. &man.smp.4; has more details. What is microcode? How do I install &intel; CPU microcode updates? Microcode is a method of programmatically implementing hardware level instructions. This allows for CPU bugs to be fixed without replacing the on board chip. Install sysutils/devcpu-data, then add: microcode_update_enable="YES" to /etc/rc.conf Hard Drives, Tape Drives, and CD and DVD Drives What kind of hard drives does &os; support? &os; supports EIDE, SATA, SCSI, and SAS drives (with a compatible controller; see the next section), and all drives using the original Western Digital interface (MFM, RLL, ESDI, and of course IDE). A few ESDI controllers that use proprietary interfaces may not work: stick to WD1002/3/6/7 interfaces and clones. Which SCSI or SAS controllers are supported? See the complete list in the Hardware Notes for &os; &rel.current; or &rel2.current;. What types of tape drives are supported? &os; supports all standard SCSI tape interfaces. Does &os; support tape changers? &os; supports SCSI changers using the &man.ch.4; device and the &man.chio.1; command. The details of how to control the changer can be found in &man.chio.1;. While AMANDA and some other products already understands changers, other applications only know how to move a tape from one point to another. In this case, keep track of which slot a tape is in and which slot the tape currently in the drive needs to go back to. Which CD-ROM and CD-RW drives are supported by &os;? Any SCSI drive connected to a supported controller is supported. Most ATAPI compatible IDE CD-ROMs are supported. &os; supports any ATAPI-compatible IDE CD-R or CD-RW drive. &os; also supports any SCSI CD-R or CD-RW drives. Install the sysutils/cdrtools port or package, then use cdrecord. Keyboards and Mice Is it possible to use a mouse outside the X Window system? The default console driver, &man.syscons.4;, provides the ability to use a mouse pointer in text consoles to cut & paste text. Run the mouse daemon, &man.moused.8;, and turn on the mouse pointer in the virtual console: &prompt.root; moused -p /dev/xxxx -t yyyy &prompt.root; vidcontrol -m on Where xxxx is the mouse device name and yyyy is a protocol type for the mouse. The mouse daemon can automatically determine the protocol type of most mice, except old serial mice. Specify the auto protocol to invoke automatic detection. If automatic detection does not work, see the &man.moused.8; manual page for a list of supported protocol types. For a PS/2 mouse, add moused_enable="YES" to /etc/rc.conf to start the mouse daemon at boot time. Additionally, to use the mouse daemon on all virtual terminals instead of just the console, add allscreens_flags="-m on" to /etc/rc.conf. When the mouse daemon is running, access to the mouse must be coordinated between the mouse daemon and other programs such as X Windows. Refer to the FAQ Why does my mouse not work with X? for more details on this issue. How do I cut and paste text with a mouse in the text console? It is not possible to remove data using the mouse. However, it is possible to copy and paste. Once the mouse daemon is running as described in the previous question, hold down button 1 (left button) and move the mouse to select a region of text. Then, press button 2 (middle button) to paste it at the text cursor. Pressing button 3 (right button) will extend the selected region of text. If the mouse does not have a middle button, it is possible to emulate one or remap buttons using mouse daemon options. See the &man.moused.8; manual page for details. My mouse has a fancy wheel and buttons. Can I use them in &os;? The answer is, unfortunately, It depends. These mice with additional features require specialized driver in most cases. Unless the mouse device driver or the user program has specific support for the mouse, it will act just like a standard two, or three button mouse. For the possible usage of wheels in the X Window environment, refer to that section. How do I use my delete key in sh and csh? For the Bourne Shell, add the following lines to ~/.shrc. See &man.sh.1; and &man.editrc.5;. bind ^? ed-delete-next-char # for console bind ^[[3~ ed-delete-next-char # for xterm For the C Shell, add the following lines to ~/.cshrc. See &man.csh.1;. bindkey ^? delete-char # for console bindkey ^[[3~ delete-char # for xterm For more information, see this page. Other Hardware Workarounds for no sound from my &man.pcm.4; sound card? Some sound cards set their output volume to 0 at every boot. Run the following command every time the machine boots: &prompt.root; mixer pcm 100 vol 100 cd 100 Does &os; support power management on my laptop? &os; supports the ACPI features found in modern hardware. Further information can be found in &man.acpi.4;. Troubleshooting Why is &os; finding the wrong amount of memory on &i386; hardware? The most likely reason is the difference between physical memory addresses and virtual addresses. The convention for most PC hardware is to use the memory area between 3.5 GB and 4 GB for a special purpose (usually for PCI). This address space is used to access PCI hardware. As a result real, physical memory cannot be accessed by that address space. What happens to the memory that should appear in that location is hardware dependent. Unfortunately, some hardware does nothing and the ability to use that last 500 MB of RAM is entirely lost. Luckily, most hardware remaps the memory to a higher location so that it can still be used. However, this can cause some confusion when watching the boot messages. On a 32-bit version of &os;, the memory appears lost, since it will be remapped above 4 GB, which a 32-bit kernel is unable to access. In this case, the solution is to build a PAE enabled kernel. See the entry on memory limits for more information. On a 64-bit version of &os;, or when running a PAE-enabled kernel, &os; will correctly detect and remap the memory so it is usable. During boot, however, it may seem as if &os; is detecting more memory than the system really has, due to the described remapping. This is normal and the available memory will be corrected as the boot process completes. Why do my programs occasionally die with Signal 11 errors? Signal 11 errors are caused when a process has attempted to access memory which the operating system has not granted it access to. If something like this is happening at seemingly random intervals, start investigating the cause. These problems can usually be attributed to either: If the problem is occurring only in a specific custom application, it is probably a bug in the code. If it is a problem with part of the base &os; system, it may also be buggy code, but more often than not these problems are found and fixed long before us general FAQ readers get to use these bits of code (that is what -CURRENT is for). It is probably not a &os; bug if the problem occurs compiling a program, but the activity that the compiler is carrying out changes each time. For example, if make buildworld fails while trying to compile ls.c into ls.o and, when run again, it fails in the same place, this is a broken build. Try updating source and try again. If the compile fails elsewhere, it is almost certainly due to hardware. In the first case, use a debugger such as &man.gdb.1; to find the point in the program which is attempting to access a bogus address and fix it. In the second case, verify which piece of hardware is at fault. Common causes of this include: The hard disks might be overheating: Check that the fans are still working, as the disk and other hardware might be overheating. The processor running is overheating: This might be because the processor has been overclocked, or the fan on the processor might have died. In either case, ensure that the hardware is running at what it is specified to run at, at least while trying to solve this problem. If it is not, clock it back to the default settings.) Regarding overclocking, it is far cheaper to have a slow system than a fried system that needs replacing! Also the community is not sympathetic to problems on overclocked systems. Dodgy memory: if multiple memory SIMMS/DIMMS are installed, pull them all out and try running the machine with each SIMM or DIMM individually to narrow the problem down to either the problematic DIMM/SIMM or perhaps even a combination. Over-optimistic motherboard settings: the BIOS settings, and some motherboard jumpers, provide options to set various timings. The defaults are often sufficient, but sometimes setting the wait states on RAM too low, or setting the RAM Speed: Turbo option will cause strange behavior. A possible idea is to set to BIOS defaults, after noting the current settings first. Unclean or insufficient power to the motherboard. Remove any unused I/O boards, hard disks, or CD-ROMs, or disconnect the power cable from them, to see if the power supply can manage a smaller load. Or try another power supply, preferably one with a little more power. For instance, if the current power supply is rated at 250 Watts, try one rated at 300 Watts. Read the section on Signal 11 for a further explanation and a discussion on how memory testing software or hardware can still pass faulty memory. There is an extensive FAQ on this at the SIG11 problem FAQ. Finally, if none of this has helped, it is possibly a bug in &os;. Follow these instructions to send a problem report. My system crashes with either Fatal trap 12: page fault in kernel mode, or panic:, and spits out a bunch of information. What should I do? The &os; developers are interested in these errors, but need more information than just the error message. Copy the full crash message. Then consult the FAQ section on kernel panics, build a debugging kernel, and get a backtrace. This might sound difficult, but does not require any programming skills. Just follow the instructions. What is the meaning of the error maxproc limit exceeded by uid %i, please see tuning(7) and login.conf(5)? The &os; kernel will only allow a certain number of processes to exist at one time. The number is based on the kern.maxusers &man.sysctl.8; variable. kern.maxusers also affects various other in-kernel limits, such as network buffers. If the machine is heavily loaded, increase kern.maxusers. This will increase these other system limits in addition to the maximum number of processes. To adjust the kern.maxusers value, see the File/Process Limits section of the Handbook. While that section refers to open files, the same limits apply to processes. If the machine is lightly loaded but running a very large number of processes, adjust the kern.maxproc tunable by defining it in /boot/loader.conf. The tunable will not get adjusted until the system is rebooted. For more information about tuning tunables, see &man.loader.conf.5;. If these processes are being run by a single user, adjust kern.maxprocperuid to be one less than the new kern.maxproc value. It must be at least one less because one system program, &man.init.8;, must always be running. Why do full screen applications on remote machines misbehave? The remote machine may be setting the terminal type to something other than xterm which is required by the &os; console. Alternatively the kernel may have the wrong values for the width and height of the terminal. Check the value of the TERM environment variable is xterm. If the remote machine does not support that try vt100. Run stty -a to check what the kernel thinks the terminal dimensions are. If they are incorrect, they can be changed by running stty rows RR cols CC. Alternatively, if the client machine has x11/xterm installed, then running resize will query the terminal for the correct dimensions and set them. Why does it take so long to connect to my computer via ssh or telnet? The symptom: there is a long delay between the time the TCP connection is established and the time when the client software asks for a password (or, in &man.telnet.1;'s case, when a login prompt appears). The problem: more likely than not, the delay is caused by the server software trying to resolve the client's IP address into a hostname. Many servers, including the Telnet and SSH servers that come with &os;, do this to store the hostname in a log file for future reference by the administrator. The remedy: if the problem occurs whenever connecting the client computer to any server, the problem is with the client. If the problem only occurs when someone connects to the server computer, the problem is with the server. If the problem is with the client, the only remedy is to fix the DNS so the server can resolve it. If this is on a local network, consider it a server problem and keep reading. If this is on the Internet, contact your ISP. If the problem is with the server on a local network, configure the server to resolve address-to-hostname queries for the local address range. See &man.hosts.5; and &man.named.8; for more information. If this is on the Internet, the problem may be that the local server's resolver is not functioning correctly. To check, try to look up another host such as www.yahoo.com. If it does not work, that is the problem. Following a fresh install of &os;, it is also possible that domain and name server information is missing from /etc/resolv.conf. This will often cause a delay in SSH, as the option UseDNS is set to yes by default in /etc/ssh/sshd_config. If this is causing the problem, either fill in the missing information in /etc/resolv.conf or set UseDNS to no in sshd_config as a temporary workaround. Why does file: table is full show up repeatedly in &man.dmesg.8;? This error message indicates that the number of available file descriptors have been exhausted on the system. Refer to the kern.maxfiles section of the Tuning Kernel Limits section of the Handbook for a discussion and solution. Why does the clock on my computer keep incorrect time? The computer has two or more clocks, and &os; has chosen to use the wrong one. Run &man.dmesg.8;, and check for lines that contain Timecounter. The one with the highest quality value that &os; chose. &prompt.root; dmesg | grep Timecounter Timecounter "i8254" frequency 1193182 Hz quality 0 Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000 Timecounter "TSC" frequency 2998570050 Hz quality 800 Timecounters tick every 1.000 msec Confirm this by checking the kern.timecounter.hardware &man.sysctl.3;. &prompt.root; sysctl kern.timecounter.hardware kern.timecounter.hardware: ACPI-fast It may be a broken ACPI timer. The simplest solution is to disable the ACPI timer in /boot/loader.conf: debug.acpi.disabled="timer" Or the BIOS may modify the TSC clock—perhaps to change the speed of the processor when running from batteries, or going into a power saving mode, but &os; is unaware of these adjustments, and appears to gain or lose time. In this example, the i8254 clock is also available, and can be selected by writing its name to the kern.timecounter.hardware &man.sysctl.3;. &prompt.root; sysctl kern.timecounter.hardware=i8254 kern.timecounter.hardware: TSC -> i8254 The computer should now start keeping more accurate time. To have this change automatically run at boot time, add the following line to /etc/sysctl.conf: kern.timecounter.hardware=i8254 What does the error swap_pager: indefinite wait buffer: mean? This means that a process is trying to page memory from disk, and the page attempt has hung trying to access the disk for more than 20 seconds. It might be caused by bad blocks on the disk drive, disk wiring, cables, or any other disk I/O-related hardware. If the drive itself is bad, disk errors will appear in /var/log/messages and in the output of dmesg. Otherwise, check the cables and connections. What is a lock order reversal? The &os; kernel uses a number of resource locks to arbitrate contention for certain resources. When multiple kernel threads try to obtain multiple resource locks, there's always the potential for a deadlock, where two threads have each obtained one of the locks and blocks forever waiting for the other thread to release one of the other locks. This sort of locking problem can be avoided if all threads obtain the locks in the same order. A run-time lock diagnostic system called &man.witness.4;, enabled in &os.current; and disabled by default for stable branches and releases, detects the potential for deadlocks due to locking errors, including errors caused by obtaining multiple resource locks with a different order from different parts of the kernel. The &man.witness.4; framework tries to detect this problem as it happens, and reports it by printing a message to the system console about a lock order reversal (often referred to also as LOR). It is possible to get false positives, as &man.witness.4; is conservative. A true positive report does not mean that a system is dead-locked; instead it should be understood as a warning that a deadlock could have happened here. Problematic LORs tend to get fixed quickly, so check the &a.current; before posting to it. What does Called ... with the following non-sleepable locks held mean? This means that a function that may sleep was called while a mutex (or other unsleepable) lock was held. The reason this is an error is because mutexes are not intended to be held for long periods of time; they are supposed to only be held to maintain short periods of synchronization. This programming contract allows device drivers to use mutexes to synchronize with the rest of the kernel during interrupts. Interrupts (under &os;) may not sleep. Hence it is imperative that no subsystem in the kernel block for an extended period while holding a mutex. To catch such errors, assertions may be added to the kernel that interact with the &man.witness.4; subsystem to emit a warning or fatal error (depending on the system configuration) when a potentially blocking call is made while holding a mutex. In summary, such warnings are non-fatal, however with unfortunate timing they could cause undesirable effects ranging from a minor blip in the system's responsiveness to a complete system lockup. For additional information about locking in &os; see &man.locking.9;. Why does buildworld/installworld die with the message touch: not found? This error does not mean that the &man.touch.1; utility is missing. The error is instead probably due to the dates of the files being set sometime in the future. If the CMOS clock is set to local time, run adjkerntz -i to adjust the kernel clock when booting into single-user mode. User Applications Where are all the user applications? Refer to the ports page for info on software packages ported to &os;. The list currently tops &os.numports; and is growing daily, so come back to check often or subscribe to the &a.announce; for periodic updates on new entries. Most ports should work on all supported versions of &os;. Those that do not are specifically marked as such. Each time a &os; release is made, a snapshot of the ports tree at the time of release in also included in the ports/ directory. &os; supports compressed binary packages to easily install and uninstall ports. Use &man.pkg.7; to control the installation of packages. How do I download the Ports tree? Should I be using SVN? Any of the methods listed here work: Use portsnap for most use cases. Refer to Using the Ports Collection for instructions on how to use this tool. Use SVN if custom patches to the ports tree are needed. Refer to Using Subversion for details. Does &os; support &java;? Yes. Refer to https://www.FreeBSD.org/java/ for more information. Why can I not build this port on my &rel2.relx; -, or &rel.relx; -STABLE machine? If the installed &os; version lags significantly behind -CURRENT or -STABLE, update the Ports Collection using the instructions in Using the Ports Collection. If the system is up-to-date, someone might have committed a change to the port which works for -CURRENT but which broke the port for -STABLE. Submit a bug report, since the Ports Collection is supposed to work for both the -CURRENT and -STABLE branches. I just tried to build INDEX using make index, and it failed. Why? First, make sure that the Ports Collection is up-to-date. Errors that affect building INDEX from an up-to-date copy of the Ports Collection are high-visibility and are thus almost always fixed immediately. There are rare cases where INDEX will not build due to odd cases involving WITH_* or WITHOUT_* variables being set in make.conf. If you suspect that this is the case, try to make INDEX with those make variables turned off before reporting it to &a.ports;. I updated the sources, now how do I update my installed ports? &os; does not include a port upgrading tool, but it does have some tools to make the upgrade process somewhat easier. Additional tools are available to simplify port handling and are described the Upgrading Ports section in the &os; Handbook. Do I need to recompile every port each time I perform a major version update? Yes! While a recent system will run with software compiled under an older release, things will randomly crash and fail to work once other ports are installed or updated. When the system is upgraded, various shared libraries, loadable modules, and other parts of the system will be replaced with newer versions. Applications linked against the older versions may fail to start or, in other cases, fail to function properly. For more information, see the section on upgrades in the &os; Handbook. Do I need to recompile every port each time I perform a minor version update? In general, no. &os; developers do their utmost to guarantee binary compatibility across all releases with the same major version number. Any exceptions will be documented in the Release Notes, and advice given there should be followed. Why is /bin/sh so minimal? Why does &os; not use bash or another shell? Many people need to write shell scripts which will be portable across many systems. That is why &posix; specifies the shell and utility commands in great detail. Most scripts are written in Bourne shell (&man.sh.1;), and because several important programming interfaces (&man.make.1;, &man.system.3;, &man.popen.3;, and analogues in higher-level scripting languages like Perl and Tcl) are specified to use the Bourne shell to interpret commands. Because the Bourne shell is so often and widely used, it is important for it to be quick to start, be deterministic in its behavior, and have a small memory footprint. The existing implementation is our best effort at meeting as many of these requirements simultaneously as we can. To keep /bin/sh small, we have not provided many of the convenience features that other shells have. That is why other more featureful shells like bash, scsh, &man.tcsh.1;, and zsh are available. Compare the memory utilization of these shells by looking at the VSZ and RSS columns in a ps -u listing. How do I create audio CDs from my MIDI files? To create audio CDs from MIDI files, first install audio/timidity++ from ports then install manually the GUS patches set by Eric A. Welsh, available at http://alleg.sourceforge.net/digmid.html. After TiMidity++ has been installed properly, MIDI files may be converted to WAV files with the following command line: &prompt.user; timidity -Ow -s 44100 -o /tmp/juke/01.wav 01.mid The WAV files can then be converted to other formats or burned onto audio CDs, as described in the &os; Handbook. Kernel Configuration I would like to customize my kernel. Is it difficult? Not at all! Check out the kernel config section of the Handbook. The new kernel will be installed to the /boot/kernel directory along with its modules, while the old kernel and its modules will be moved to the /boot/kernel.old directory. If a mistake is made in the configuration, simply boot the previous version of the kernel. Why is my kernel so big? GENERIC kernels shipped with &os; are compiled in debug mode. Kernels built in debug mode contain debug data in separate files that are used for debugging. &os; releases prior to 11.0 store these debug files in the same directory as the kernel itself, /boot/kernel/. In &os; 11.0 and later the debug files are stored in /usr/lib/debug/boot/kernel/. Note that there will be little or no performance loss from running a debug kernel, and it is useful to keep one around in case of a system panic. When running low on disk space, there are different options to reduce the size of /boot/kernel/ and /usr/lib/debug/. To not install the symbol files, make sure the following line exists in /etc/src.conf: WITHOUT_KERNEL_SYMBOLS=yes For more information see &man.src.conf.5;. If you want to avoid building debug files altogether, make sure that both of the following are true: This line does not exist in the kernel configuration file: makeoptions DEBUG=-g Do not run &man.config.8; with . Either of the above settings will cause the kernel to be built in debug mode. To build and install only the specified modules, list them in /etc/make.conf: MODULES_OVERRIDE= accf_http ipfw Replace accf_httpd ipfw with a list of needed modules. Only the listed modules will be built. This reduces the size of the kernel directory and decreases the amount of time needed to build the kernel. For more information, read /usr/share/examples/etc/make.conf. Unneeded devices can be removed from the kernel to further reduce the size. See for more information. To put any of these options into effect, follow the instructions to build and install the new kernel. For reference, the &os; 11 &arch.amd64; kernel (/boot/kernel/kernel) is approximately 25 MB. Why does every kernel I try to build fail to compile, even GENERIC? There are a number of possible causes for this problem: The source tree is different from the one used to build the currently running system. When attempting an upgrade, read /usr/src/UPDATING, paying particular attention to the COMMON ITEMS section at the end. The make buildkernel command did not complete successfully. The make buildkernel target relies on files generated by the make buildworld target to complete its job correctly. Even when building &os;-STABLE, it is possible that the source tree was fetched at a time when it was either being modified or it was broken. Only releases are guaranteed to be buildable, although &os;-STABLE builds fine the majority of the time. Try re-fetching the source tree and see if the problem goes away. Try using a different mirror in case the previous one is having problems. Which scheduler is in use on a running system? The name of the scheduler currently being used is directly available as the value of the kern.sched.name sysctl: &prompt.user; sysctl kern.sched.name kern.sched.name: ULE What is kern.sched.quantum? kern.sched.quantum is the maximum number of ticks a process can run without being preempted in the 4BSD scheduler. Disks, File Systems, and Boot Loaders How can I add my new hard disk to my &os; system? See the Adding Disks section in the &os; Handbook. How do I move my system over to my huge new disk? The best way is to reinstall the operating system on the new disk, then move the user data over. This is highly recommended when tracking -STABLE for more than one release or when updating a release instead of installing a new one. Install booteasy on both disks with &man.boot0cfg.8; and dual boot until you are happy with the new configuration. Skip the next paragraph to find out how to move the data after doing this. Alternatively, partition and label the new disk with either &man.sade.8; or &man.gpart.8;. If the disks are MBR-formatted, booteasy can be installed on both disks with &man.boot0cfg.8; so that the computer can dual boot to the old or new system after the copying is done. Once the new disk set up, the data cannot just be copied. Instead, use tools that understand device files and system flags, such as &man.dump.8;. Although it is recommended to move the data while in single-user mode, it is not required. When the disks are formatted with UFS, never use anything but &man.dump.8; and &man.restore.8; to move the root file system. These commands should also be used when moving a single partition to another empty partition. The sequence of steps to use dump to move the data from one UFS partitions to a new partition is: newfs the new partition. mount it on a temporary mount point. cd to that directory. dump the old partition, piping output to the new one. For example, to move /dev/ada1s1a with /mnt as the temporary mount point, type: &prompt.root; newfs /dev/ada1s1a &prompt.root; mount /dev/ada1s1a /mnt &prompt.root; cd /mnt &prompt.root; dump 0af - / | restore rf - Rearranging partitions with dump takes a bit more work. To merge a partition like /var into its parent, create the new partition large enough for both, move the parent partition as described above, then move the child partition into the empty directory that the first move created: &prompt.root; newfs /dev/ada1s1a &prompt.root; mount /dev/ada1s1a /mnt &prompt.root; cd /mnt &prompt.root; dump 0af - / | restore rf - &prompt.root; cd var &prompt.root; dump 0af - /var | restore rf - To split a directory from its parent, say putting /var on its own partition when it was not before, create both partitions, then mount the child partition on the appropriate directory in the temporary mount point, then move the old single partition: &prompt.root; newfs /dev/ada1s1a &prompt.root; newfs /dev/ada1s1d &prompt.root; mount /dev/ada1s1a /mnt &prompt.root; mkdir /mnt/var &prompt.root; mount /dev/ada1s1d /mnt/var &prompt.root; cd /mnt &prompt.root; dump 0af - / | restore rf - The &man.cpio.1; and &man.pax.1; utilities are also available for moving user data. These are known to lose file flag information, so use them with caution. Which partitions can safely use Soft Updates? I have heard that Soft Updates on / can cause problems. What about Journaled Soft Updates? Short answer: Soft Updates can usually be safely used on all partitions. Long answer: Soft Updates has two characteristics that may be undesirable on certain partitions. First, a Soft Updates partition has a small chance of losing data during a system crash. The partition will not be corrupted as the data will simply be lost. Second, Soft Updates can cause temporary space shortages. When using Soft Updates, the kernel can take up to thirty seconds to write changes to the physical disk. When a large file is deleted the file still resides on disk until the kernel actually performs the deletion. This can cause a very simple race condition. Suppose one large file is deleted and another large file is immediately created. The first large file is not yet actually removed from the physical disk, so the disk might not have enough room for the second large file. This will produce an error that the partition does not have enough space, even though a large chunk of space has just been released. A few seconds later, the file creation works as expected. If a system should crash after the kernel accepts a chunk of data for writing to disk, but before that data is actually written out, data could be lost. This risk is extremely small, but generally manageable. These issues affect all partitions using Soft Updates. So, what does this mean for the root partition? Vital information on the root partition changes very rarely. If the system crashed during the thirty-second window after such a change is made, it is possible that data could be lost. This risk is negligible for most applications, but be aware that it exists. If the system cannot tolerate this much risk, do not use Soft Updates on the root file system! / is traditionally one of the smallest partitions. If /tmp is on /, there may be intermittent space problems. Symlinking /tmp to /var/tmp will solve this problem. Finally, &man.dump.8; does not work in live mode (-L) on a filesystem, with Journaled Soft Updates (SU+J). Can I mount other foreign file systems under &os;? &os; supports a variety of other file systems. UFS UFS CD-ROMs can be mounted directly on &os;. Mounting disk partitions from Digital UNIX and other systems that support UFS may be more complex, depending on the details of the disk partitioning for the operating system in question. ext2/ext3 &os; supports ext2fs and ext3fs partitions. See &man.ext2fs.5; for more information. NTFS FUSE based NTFS support is available as a port (sysutils/fusefs-ntfs). For more information see ntfs-3g. FAT &os; includes a read-write FAT driver. For more information, see &man.mount.msdosfs.8;. ZFS &os; includes a port of &sun;'s ZFS driver. The current recommendation is to use it only on &arch.amd64; platforms with sufficient memory. For more information, see &man.zfs.8;. &os; includes the Network File System NFS and the &os; Ports Collection provides several FUSE applications to support many other file systems. How do I mount a secondary DOS partition? The secondary DOS partitions are found after all the primary partitions. For example, if E is the second DOS partition on the second SCSI drive, there will be a device file for slice 5 in /dev. To mount it: &prompt.root; mount -t msdosfs /dev/da1s5 /dos/e Is there a cryptographic file system for &os;? Yes, &man.gbde.8; and &man.geli.8;. See the Encrypting Disk Partitions section of the &os; Handbook. How do I boot &os; and &linux; using GRUB? To boot &os; using GRUB, add the following to either /boot/grub/menu.lst or /boot/grub/grub.conf, depending upon which is used by the &linux; distribution. title &os; 9.1 root (hd0,a) kernel /boot/loader Where hd0,a points to the root partition on the first disk. To specify the slice number, use something like this (hd0,2,a). By default, if the slice number is omitted, GRUB searches the first slice which has the a partition. How do I boot &os; and &linux; using BootEasy? Install LILO at the start of the &linux; boot partition instead of in the Master Boot Record. You can then boot LILO from BootEasy. This is recommended when running &windows; and &linux; as it makes it simpler to get &linux; booting again if &windows; is reinstalled. How do I change the boot prompt from ??? to something more meaningful? This cannot be accomplished with the standard boot manager without rewriting it. There are a number of other boot managers in the sysutils category of the Ports Collection. How do I use a new removable drive? If the drive already has a file system on it, use a command like this: &prompt.root; mount -t msdosfs /dev/da0s1 /mnt If the drive will only be used with &os; systems, partition it with UFS or ZFS. This will provide long filename support, improvement in performance, and stability. If the drive will be used by other operating systems, a more portable choice, such as msdosfs, is better. &prompt.root; dd if=/dev/zero of=/dev/da0 count=2 &prompt.root; gpart create -s GPT /dev/da0 &prompt.root; gpart add -t freebsd-ufs /dev/da0 Finally, create a new file system: &prompt.root; newfs /dev/da0p1 and mount it: &prompt.root; mount /dev/da0s1 /mnt It is a good idea to add a line to /etc/fstab (see &man.fstab.5;) so you can just type mount /mnt in the future: /dev/da0p1 /mnt ufs rw,noauto 0 0 Why do I get Incorrect super block when mounting a CD? The type of device to mount must be specified. This is described in the Handbook section on Using Data CDs. Why do I get Device not configured when mounting a CD? This generally means that there is no CD in the drive, or the drive is not visible on the bus. Refer to the Using Data CDs section of the Handbook for a detailed discussion of this issue. Why do all non-English characters in filenames show up as ? on my CDs when mounted in &os;? The CD probably uses the Joliet extension for storing information about files and directories. This is discussed in the Handbook section on Using Data CD-ROMs. A CD burned under &os; cannot be read under any other operating system. Why? This means a raw file was burned to the CD, rather than creating an ISO 9660 file system. Take a look at the Handbook section on Using Data CDs. How can I create an image of a data CD? This is discussed in the Handbook section on Writing Data to an ISO File System. For more on working with CD-ROMs, see the Creating CDs Section in the Storage chapter in the Handbook. Why can I not mount an audio CD? Trying to mount an audio CD will produce an error like cd9660: /dev/cd0: Invalid argument. This is because mount only works on file systems. Audio CDs do not have file systems; they just have data. Instead, use a program that reads audio CDs, such as the audio/xmcd package or port. How do I mount a multi-session CD? By default, &man.mount.8; will attempt to mount the last data track (session) of a CD. To load an earlier session, use the command line argument. Refer to &man.mount.cd9660.8; for specific examples. How do I let ordinary users mount CD-ROMs, DVDs, USB drives, and other removable media? As root set the sysctl variable vfs.usermount to 1. &prompt.root; sysctl vfs.usermount=1 To make this persist across reboots, add the line vfs.usermount=1 to /etc/sysctl.conf so that it is reset at system boot time. Users can only mount devices they have read permissions to. To allow users to mount a device permissions must be set in /etc/devfs.conf. For example, to allow users to mount the first USB drive add: # Allow all users to mount a USB drive. own /dev/da0 root:operator perm /dev/da0 0666 All users can now mount devices they could read onto a directory that they own: &prompt.user; mkdir ~/my-mount-point &prompt.user; mount -t msdosfs /dev/da0 ~/my-mount-point Unmounting the device is simple: &prompt.user; umount ~/my-mount-point Enabling vfs.usermount, however, has negative security implications. A better way to access &ms-dos; formatted media is to use the emulators/mtools package in the Ports Collection. The device name used in the previous examples must be changed according to the configuration. The du and df commands show different amounts of disk space available. What is going on? This is due to how these commands actually work. du goes through the directory tree, measures how large each file is, and presents the totals. df just asks the file system how much space it has left. They seem to be the same thing, but a file without a directory entry will affect df but not du. When a program is using a file, and the file is deleted, the file is not really removed from the file system until the program stops using it. The file is immediately deleted from the directory listing, however. As an example, consider a file large enough to affect the output of du and df. A file being viewed with more can be deleted wihout causing an error. The entry is removed from the directory so no other program or user can access it. However, du shows that it is gone as it has walked the directory tree and the file is not listed. df shows that it is still there, as the file system knows that more is still using that space. Once the more session ends, du and df will agree. This situation is common on web servers. Many people set up a &os; web server and forget to rotate the log files. The access log fills up /var. The new administrator deletes the file, but the system still complains that the partition is full. Stopping and restarting the web server program would free the file, allowing the system to release the disk space. To prevent this from happening, set up &man.newsyslog.8;. Note that Soft Updates can delay the freeing of disk space and it can take up to 30 seconds for the change to be visible. How can I add more swap space? This section of the Handbook describes how to do this. Why does &os; see my disk as smaller than the manufacturer says it is? Disk manufacturers calculate gigabytes as a billion bytes each, whereas &os; calculates them as 1,073,741,824 bytes each. This explains why, for example, &os;'s boot messages will report a disk that supposedly has 80 GB as holding 76,319 MB. Also note that &os; will (by default) reserve 8% of the disk space. How is it possible for a partition to be more than 100% full? A portion of each UFS partition (8%, by default) is reserved for use by the operating system and the root user. &man.df.1; does not count that space when calculating the Capacity column, so it can exceed 100%. Notice that the Blocks column is always greater than the sum of the Used and Avail columns, usually by a factor of 8%. For more details, look up in &man.tunefs.8;. ZFS What is the minimum amount of RAM one should have to run ZFS? A minimum of 4GB of RAM is required for comfortable usage, but individual workloads can vary widely. What is the ZIL and when does it get used? The ZIL (ZFS intent log) is a write log used to implement posix write commitment semantics across crashes. Normally writes are bundled up into transaction groups and written to disk when filled (Transaction Group Commit). However syscalls like &man.fsync.2; require a commitment that the data is written to stable storage before returning. The ZIL is needed for writes that have been acknowledged as written but which are not yet on disk as part of a transaction. The transaction groups are timestamped. In the event of a crash the last valid timestamp is found and missing data is merged in from the ZIL. Do I need a SSD for ZIL? By default, ZFS stores the ZIL in the pool with all the data. If an application has a heavy write load, storing the ZIL in a separate device that has very fast synchronous, sequential write performance can improve overall system. For other workloads, a SSD is unlikely to make much of an improvement. What is the L2ARC? The L2ARC is a read cache stored on a fast device such as an SSD. This cache is not persistent across reboots. Note that RAM is used as the first layer of cache and the L2ARC is only needed if there is insufficient RAM. L2ARC needs space in the ARC to index it. So, perversely, a working set that fits perfectly in the ARC will not fit perfectly any more if a L2ARC is used because part of the ARC is holding the L2ARC index, pushing part of the working set into the L2ARC which is slower than RAM. Is enabling deduplication advisable? Generally speaking, no. Deduplication takes up a significant amount of RAM and may slow down read and write disk access times. Unless one is storing data that is very heavily duplicated, such as virtual machine images or user backups, it is possible that deduplication will do more harm than good. Another consideration is the inability to revert deduplication status. If data is written when deduplication is enabled, disabling dedup will not cause those blocks which were deduplicated to be replicated until they are next modified. Deduplication can also lead to some unexpected situations. In particular, deleting files may become much slower. I cannot delete or create files on my ZFS pool. How can I fix this? This could happen because the pool is 100% full. ZFS requires space on the disk to write transaction metadata. To restore the pool to a usable state, truncate the file to delete: &prompt.user; truncate -s 0 unimportant-file File truncation works because a new transaction is not started, new spare blocks are created instead. On systems with additional ZFS dataset tuning, such as deduplication, the space may not be immediately available Does ZFS support TRIM for Solid State Drives? ZFS TRIM support was added to &os; 10-CURRENT with revision r240868. ZFS TRIM support was added to all &os;-STABLE branches in r252162 and r251419, respectively. ZFS TRIM is enabled by default, and can be turned off by adding this line to /etc/sysctl.conf: vfs.zfs.trim_disable=1 ZFS TRIM may not work with all configurations, such as a ZFS filesystem on a GELI-backed device. System Administration Where are the system start-up configuration files? The primary configuration file is /etc/defaults/rc.conf which is described in &man.rc.conf.5;. System startup scripts such as /etc/rc and /etc/rc.d, which are described in &man.rc.8;, include this file. Do not edit this file! Instead, to edit an entry in /etc/defaults/rc.conf, copy the line into /etc/rc.conf and change it there. For example, if to start &man.named.8;, the included DNS server: &prompt.root; echo 'named_enable="YES"' >> /etc/rc.conf To start up local services, place shell scripts in the /usr/local/etc/rc.d directory. These shell scripts should be set executable, the default file mode is 555. How do I add a user easily? Use the &man.adduser.8; command, or the &man.pw.8; command for more complicated situations. To remove the user, use the &man.rmuser.8; command or, if necessary, &man.pw.8;. Why do I keep getting messages like root: not found after editing /etc/crontab? This is normally caused by editing the system crontab. This is not the correct way to do things as the system crontab has a different format to the per-user crontabs. The system crontab has an extra field, specifying which user to run the command as. &man.cron.8; assumes this user is the first word of the command to execute. Since no such command exists, this error message is displayed. To delete the extra, incorrect crontab: &prompt.root; crontab -r Why do I get the error, you are not in the correct group to su root when I try to su to root? This is a security feature. In order to su to root, or any other account with superuser privileges, the user account must be a member of the wheel group. If this feature were not there, anybody with an account on a system who also found out root's password would be able to gain superuser level access to the system. To allow someone to su to root, put them in the wheel group using pw: &prompt.root; pw groupmod wheel -m lisa The above example will add user lisa to the group wheel. I made a mistake in rc.conf, or another startup file, and now I cannot edit it because the file system is read-only. What should I do? Restart the system using boot -s at the loader prompt to enter single-user mode. When prompted for a shell pathname, press Enter and run mount -urw / to re-mount the root file system in read/write mode. You may also need to run mount -a -t ufs to mount the file system where your favorite editor is defined. If that editor is on a network file system, either configure the network manually before mounting the network file systems, or use an editor which resides on a local file system, such as &man.ed.1;. In order to use a full screen editor such as &man.vi.1; or &man.emacs.1;, run export TERM=xterm so that these editors can load the correct data from the &man.termcap.5; database. After performing these steps, edit /etc/rc.conf to fix the syntax error. The error message displayed immediately after the kernel boot messages should indicate the number of the line in the file which is at fault. Why am I having trouble setting up my printer? See the Handbook entry on printing for troubleshooting tips. How can I correct the keyboard mappings for my system? Refer to the Handbook section on using localization, specifically the section on console setup. Why can I not get user quotas to work properly? It is possible that the kernel is not configured to use quotas. In this case, add the following line to the kernel configuration file and recompile the kernel: options QUOTA Refer to the Handbook entry on quotas for full details. Do not turn on quotas on /. Put the quota file on the file system that the quotas are to be enforced on: File System Quota file /usr /usr/admin/quotas /home /home/admin/quotas … … Does &os; support System V IPC primitives? Yes, &os; supports System V-style IPC, including shared memory, messages and semaphores, in the GENERIC kernel. With a custom kernel, support may be loaded with the sysvshm.ko, sysvsem.ko and sysvmsg.ko kernel modules, or enabled in the custom kernel by adding the following lines to the kernel configuration file: options SYSVSHM # enable shared memory options SYSVSEM # enable for semaphores options SYSVMSG # enable for messaging Recompile and install the kernel. What other mail-server software can I use instead of Sendmail? The Sendmail server is the default mail-server software for &os;, but it can be replaced with another MTA installed from the Ports Collection. Available ports include mail/exim, mail/postfix, and mail/qmail. Search the mailing lists for discussions regarding the advantages and disadvantages of the available MTAs. I have forgotten the root password! What do I do? Do not panic! Restart the system, type boot -s at the Boot: prompt to enter single-user mode. At the question about the shell to use, hit Enter which will display a &prompt.root; prompt. Enter mount -urw / to remount the root file system read/write, then run mount -a to remount all the file systems. Run passwd root to change the root password then run &man.exit.1; to continue booting. If you are still prompted to give the root password when entering the single-user mode, it means that the console has been marked as insecure in /etc/ttys. In this case, it will be required to boot from a &os; installation disk, choose the Live CD or Shell at the beginning of the install process and issue the commands mentioned above. Mount the specific partition in this case and then chroot to it. For example, replace mount -urw / with mount /dev/ada0p1 /mnt; chroot /mnt for a system on ada0p1. If the root partition cannot be mounted from single-user mode, it is possible that the partitions are encrypted and it is impossible to mount them without the access keys. For more information see the section about encrypted disks in the &os; Handbook. How do I keep ControlAltDelete from rebooting the system? When using &man.syscons.4;, the default console driver, build and install a new kernel with this line in the configuration file: options SC_DISABLE_REBOOT This can also be done by setting the following &man.sysctl.8; which does not require a reboot or kernel recompile: &prompt.root; sysctl hw.syscons.kbd_reboot=0 The above two methods are exclusive: The &man.sysctl.8; does not exist if the kernel is compiled with SC_DISABLE_REBOOT. How do I reformat DOS text files to &unix; ones? Use this &man.perl.1; command: &prompt.user; perl -i.bak -npe 's/\r\n/\n/g' file(s) where file(s) is one or more files to process. The modification is done in-place, with the original file stored with a .bak extension. Alternatively, use &man.tr.1;: &prompt.user; tr -d '\r' < dos-text-file > unix-file dos-text-file is the file containing DOS text while unix-file will contain the converted output. This can be quite a bit faster than using perl. Yet another way to reformat DOS text files is to use the converters/dosunix port from the Ports Collection. Consult its documentation about the details. How do I re-read /etc/rc.conf and re-start /etc/rc without a reboot? Go into single-user mode and then back to multi-user mode: &prompt.root; shutdown now &prompt.root; return &prompt.root; exit I tried to update my system to the latest -STABLE, but got -BETAx, -RC or -PRERELEASE! What is going on? Short answer: it is just a name. RC stands for Release Candidate. It signifies that a release is imminent. In &os;, -PRERELEASE is typically synonymous with the code freeze before a release. (For some releases, the -BETA label was used in the same way as -PRERELEASE.) Long answer: &os; derives its releases from one of two places. Major, dot-zero, releases, such as 9.0-RELEASE are branched from the head of the development stream, commonly referred to as -CURRENT. Minor releases, such as 6.3-RELEASE or 5.2-RELEASE, have been snapshots of the active -STABLE branch. Starting with 4.3-RELEASE, each release also now has its own branch which can be tracked by people requiring an extremely conservative rate of development (typically only security advisories). When a release is about to be made, the branch from which it will be derived from has to undergo a certain process. Part of this process is a code freeze. When a code freeze is initiated, the name of the branch is changed to reflect that it is about to become a release. For example, if the branch used to be called 6.2-STABLE, its name will be changed to 6.3-PRERELEASE to signify the code freeze and signify that extra pre-release testing should be happening. Bug fixes can still be committed to be part of the release. When the source code is in shape for the release the name will be changed to 6.3-RC to signify that a release is about to be made from it. Once in the RC stage, only the most critical bugs found can be fixed. Once the release (6.3-RELEASE in this example) and release branch have been made, the branch will be renamed to 6.3-STABLE. For more information on version numbers and the various Subversion branches, refer to the Release Engineering article. I tried to install a new kernel, and the &man.chflags.1; failed. How do I get around this? Short answer: the security level is greater than 0. Reboot directly to single-user mode to install the kernel. Long answer: &os; disallows changing system flags at security levels greater than 0. To check the current security level: &prompt.root; sysctl kern.securelevel The security level cannot be lowered in multi-user mode, so boot to single-user mode to install the kernel, or change the security level in /etc/rc.conf then reboot. See the &man.init.8; manual page for details on securelevel, and see /etc/defaults/rc.conf and the &man.rc.conf.5; manual page for more information on rc.conf. I cannot change the time on my system by more than one second! How do I get around this? Short answer: the system is at a security level greater than 1. Reboot directly to single-user mode to change the date. Long answer: &os; disallows changing the time by more that one second at security levels greater than 1. To check the security level: &prompt.root; sysctl kern.securelevel The security level cannot be lowered in multi-user mode. Either boot to single-user mode to change the date or change the security level in /etc/rc.conf and reboot. See the &man.init.8; manual page for details on securelevel, and see /etc/defaults/rc.conf and the &man.rc.conf.5; manual page for more information on rc.conf. Why is rpc.statd using 256 MB of memory? No, there is no memory leak, and it is not using 256 MB of memory. For convenience, rpc.statd maps an obscene amount of memory into its address space. There is nothing terribly wrong with this from a technical standpoint; it just throws off things like &man.top.1; and &man.ps.1;. &man.rpc.statd.8; maps its status file (resident on /var) into its address space; to save worrying about remapping it later when it needs to grow, it maps it with a generous size. This is very evident from the source code, where one can see that the length argument to &man.mmap.2; is 0x10000000, or one sixteenth of the address space on an IA32, or exactly 256 MB. Why can I not unset the schg file flag? The system is running a securelevel greater than 0. Lower the securelevel and try again. For more information, see the FAQ entry on securelevel and the &man.init.8; manual page. What is vnlru? vnlru flushes and frees vnodes when the system hits the kern.maxvnodes limit. This kernel thread sits mostly idle, and only activates when there is a huge amount of RAM and users are accessing tens of thousands of tiny files. What do the various memory states displayed by top mean? Active: pages recently statistically used. Inactive: pages recently statistically unused. Cache: (most often) pages that have percolated from inactive to a status where they maintain their data, but can often be immediately reused (either with their old association, or reused with a new association). There can be certain immediate transitions from active to cache state if the page is known to be clean (unmodified), but that transition is a matter of policy, depending upon the algorithm choice of the VM system maintainer. Free: pages without data content, and can be immediately used in certain circumstances where cache pages might be ineligible. Free pages can be reused at interrupt or process state. Wired: pages that are fixed into memory, usually for kernel purposes, but also sometimes for special use in processes. Pages are most often written to disk (sort of a VM sync) when they are in the inactive state, but active pages can also be synced. This depends upon the CPU tracking of the modified bit being available, and in certain situations there can be an advantage for a block of VM pages to be synced, whether they are active or inactive. In most common cases, it is best to think of the inactive queue to be a queue of relatively unused pages that might or might not be in the process of being written to disk. Cached pages are already synced, not mapped, but available for immediate process use with their old association or with a new association. Free pages are available at interrupt level, but cached or free pages can be used at process state for reuse. Cache pages are not adequately locked to be available at interrupt level. There are some other flags (e.g., busy flag or busy count) that might modify some of the described rules. How much free memory is available? There are a couple of kinds of free memory. One kind is the amount of memory immediately available without paging anything else out. That is approximately the size of cache queue + size of free queue (with a derating factor, depending upon system tuning). Another kind of free memory is the total amount of VM space. That can be complex, but is dependent upon the amount of swap space and memory. Other kinds of free memory descriptions are also possible, but it is relatively useless to define these, but rather it is important to make sure that the paging rate is kept low, and to avoid running out of swap space. What is /var/empty? /var/empty is a directory that the &man.sshd.8; program uses when performing privilege separation. The /var/empty directory is empty, owned by root and has the schg flag set. This directory should not be deleted. I just changed /etc/newsyslog.conf. How can I check if it does what I expect? To see what &man.newsyslog.8; will do, use the following: &prompt.user; newsyslog -nrvv My time is wrong, how can I change the timezone? Use &man.tzsetup.8;. The X Window System and Virtual Consoles What is the X Window System? The X Window System (commonly X11) is the most widely available windowing system capable of running on &unix; or &unix; like systems, including &os;. The X.Org Foundation administers the X protocol standards, with the current reference implementation, version 11 release &xorg.version;, so references are often shortened to X11. Many implementations are available for different architectures and operating systems. An implementation of the server-side code is properly known as an X server. I want to run &xorg;, how do I go about it? To install &xorg; do one of the following: Use the x11/xorg meta-port, which builds and installs every &xorg; component. Use x11/xorg-minimal, which builds and installs only the necessary &xorg; components. Install &xorg; from &os; packages: &prompt.root; pkg install xorg After the installation of &xorg;, follow the instructions from the X11 Configuration section of the &os; Handbook. I tried to run X, but I get a No devices detected. error when I type startx. What do I do now? The system is probably running at a raised securelevel. It is not possible to start X at a raised securelevel because X requires write access to &man.io.4;. For more information, see at the &man.init.8; manual page. There are two solutions to the problem: set the securelevel back down to zero or run &man.xdm.1; (or an alternative display manager) at boot time before the securelevel is raised. See for more information about running &man.xdm.1; at boot time. Why does my mouse not work with X? When using &man.syscons.4;, the default console driver, &os; can be configured to support a mouse pointer on each virtual screen. To avoid conflicting with X, &man.syscons.4; supports a virtual device called /dev/sysmouse. All mouse events received from the real mouse device are written to the &man.sysmouse.4; device via &man.moused.8;. To use the mouse on one or more virtual consoles, and use X, see and set up &man.moused.8;. Then edit /etc/X11/xorg.conf and make sure the following lines exist: Section "InputDevice" Option "Protocol" "SysMouse" Option "Device" "/dev/sysmouse" ..... Starting with &xorg; version 7.4, the InputDevice sections in xorg.conf are ignored in favor of autodetected devices. To restore the old behavior, add the following line to the ServerLayout or ServerFlags section: Option "AutoAddDevices" "false" Some people prefer to use /dev/mouse under X. To make this work, /dev/mouse should be linked to /dev/sysmouse (see &man.sysmouse.4;) by adding the following line to /etc/devfs.conf (see &man.devfs.conf.5;): link sysmouse mouse This link can be created by restarting &man.devfs.5; with the following command (as root): &prompt.root; service devfs restart My mouse has a fancy wheel. Can I use it in X? Yes, if X is configured for a 5 button mouse. To do this, add the lines Buttons 5 and ZAxisMapping 4 5 to the InputDevice section of /etc/X11/xorg.conf, as seen in this example: Section "InputDevice" Identifier "Mouse1" Driver "mouse" Option "Protocol" "auto" Option "Device" "/dev/sysmouse" Option "Buttons" "5" Option "ZAxisMapping" "4 5" EndSection To use the mouse in Emacs, also add the following lines to~/.emacs: ;; wheel mouse (global-set-key [mouse-4] 'scroll-down) (global-set-key [mouse-5] 'scroll-up) My laptop has a Synaptics touchpad. Can I use it in X? Yes, after configuring a few things to make it work. In order to use the Xorg synaptics driver, first remove moused_enable from rc.conf. To enable synaptics, add the following line to /boot/loader.conf: hw.psm.synaptics_support="1" Add the following to /etc/X11/xorg.conf: Section "InputDevice" Identifier "Touchpad0" Driver "synaptics" Option "Protocol" "psm" Option "Device" "/dev/psm0" EndSection And be sure to add the following into the ServerLayout section: InputDevice "Touchpad0" "SendCoreEvents" How do I use remote X displays? For security reasons, the default setting is to not allow a machine to remotely open a window. To enable this feature, start X with the optional argument: &prompt.user; startx -listen_tcp What is a virtual console and how do I make more? Virtual consoles provide several simultaneous sessions on the same machine without doing anything complicated like setting up a network or running X. When the system starts, it will display a login prompt on the monitor after displaying all the boot messages. Type in your login name and password to start working on the first virtual console. To start another session, perhaps to look at documentation for a program or to read mail while waiting for an FTP transfer to finish, hold down Alt and press F2. This will display the login prompt for the second virtual console. To go back to the original session, press AltF1. The default &os; installation has eight virtual consoles enabled. AltF1, AltF2, AltF3, and so on will switch between these virtual consoles. To enable more of virtual consoles, edit /etc/ttys (see &man.ttys.5;) and add entries for ttyv8 to ttyvc, after the comment on Virtual terminals: # Edit the existing entry for ttyv8 in /etc/ttys and change # "off" to "on". ttyv8 "/usr/libexec/getty Pc" xterm on secure ttyv9 "/usr/libexec/getty Pc" xterm on secure ttyva "/usr/libexec/getty Pc" xterm on secure ttyvb "/usr/libexec/getty Pc" xterm on secure The more virtual terminals, the more resources that are used. This can be problematic on systems with 8 MB RAM or less. Consider changing secure to insecure. In order to run an X server, at least one virtual terminal must be left to off for it to use. This means that only eleven of the Alt-function keys can be used as virtual consoles so that one is left for the X server. For example, to run X and eleven virtual consoles, the setting for virtual terminal 12 should be: ttyvb "/usr/libexec/getty Pc" xterm off secure The easiest way to activate the virtual consoles is to reboot. How do I access the virtual consoles from X? Use CtrlAltFn to switch back to a virtual console. Press CtrlAltF1 to return to the first virtual console. Once at a text console, use AltFn to move between them. To return to the X session, switch to the virtual console running X. If X was started from the command line using startx, the X session will attach to the next unused virtual console, not the text console from which it was invoked. For eight active virtual terminals, X will run on the ninth, so use AltF9. How do I start XDM on boot? There are two schools of thought on how to start &man.xdm.1;. One school starts xdm from /etc/ttys (see &man.ttys.5;) using the supplied example, while the other runs xdm from rc.local (see &man.rc.8;) or from an X script in /usr/local/etc/rc.d. Both are equally valid, and one may work in situations where the other does not. In both cases the result is the same: X will pop up a graphical login prompt. The &man.ttys.5; method has the advantage of documenting which vty X will start on and passing the responsibility of restarting the X server on logout to &man.init.8;. The &man.rc.8; method makes it easy to kill xdm if there is a problem starting the X server. If loaded from &man.rc.8;, xdm should be started without any arguments. xdm must start after &man.getty.8; runs, or else getty and xdm will conflict, locking out the console. The best way around this is to have the script sleep 10 seconds or so then launch xdm. When starting xdm from /etc/ttys, there still is a chance of conflict between xdm and &man.getty.8;. One way to avoid this is to add the vt number in /usr/local/lib/X11/xdm/Xservers: :0 local /usr/local/bin/X vt4 The above example will direct the X server to run in /dev/ttyv3. Note the number is offset by one. The X server counts the vty from one, whereas the &os; kernel numbers the vty from zero. Why do I get Couldn't open console when I run xconsole? When X is started with startx, the permissions on /dev/console will not get changed, resulting in things like xterm -C and xconsole not working. This is because of the way console permissions are set by default. On a multi-user system, one does not necessarily want just any user to be able to write on the system console. For users who are logging directly onto a machine with a VTY, the &man.fbtab.5; file exists to solve such problems. In a nutshell, make sure an uncommented line of the form is in /etc/fbtab (see &man.fbtab.5;): /dev/ttyv0 0600 /dev/console It will ensure that whomever logs in on /dev/ttyv0 will own the console. Why does my PS/2 mouse misbehave under X? The mouse and the mouse driver may have become out of synchronization. In rare cases, the driver may also erroneously report synchronization errors: psmintr: out of sync (xxxx != yyyy) If this happens, disable the synchronization check code by setting the driver flags for the PS/2 mouse driver to 0x100. This can be easiest achieved by adding hint.psm.0.flags="0x100" to /boot/loader.conf and rebooting. How do I reverse the mouse buttons? Type xmodmap -e "pointer = 3 2 1". Add this command to ~/.xinitrc or ~/.xsession to make it happen automatically. How do I install a splash screen and where do I find them? The detailed answer for this question can be found in the Boot Time Splash Screens section of the &os; Handbook. Can I use the Windows keys on my keyboard in X? Yes. Use &man.xmodmap.1; to define which functions the keys should perform. Assuming all Windows keyboards are standard, the keycodes for these three keys are the following: 115 — Windows key, between the left-hand Ctrl and Alt keys 116 — Windows key, to the right of AltGr 117 — Menu, to the left of the right-hand Ctrl To have the left Windows key print a comma, try this. &prompt.root; xmodmap -e "keycode 115 = comma" To have the Windows key-mappings enabled automatically every time X is started, either put the xmodmap commands in ~/.xinitrc or, preferably, create a ~/.xmodmaprc and include the xmodmap options, one per line, then add the following line to ~/.xinitrc: xmodmap $HOME/.xmodmaprc For example, to map the 3 keys to be F13, F14, and F15, respectively. This would make it easy to map them to useful functions within applications or the window manager. To do this, put the following in ~/.xmodmaprc. keycode 115 = F13 keycode 116 = F14 keycode 117 = F15 For the x11-wm/fvwm2 desktop manager, one could map the keys so that F13 iconifies or de-iconifies the window the cursor is in, F14 brings the window the cursor is in to the front or, if it is already at the front, pushes it to the back, and F15 pops up the main Workplace menu even if the cursor is not on the desktop, which is useful when no part of the desktop is visible. The following entries in ~/.fvwmrc implement the aforementioned setup: Key F13 FTIWS A Iconify Key F14 FTIWS A RaiseLower Key F15 A A Menu Workplace Nop How can I get 3D hardware acceleration for &opengl;? The availability of 3D acceleration depends on the version of &xorg; and the type of video chip. For an nVidia chip, use the binary drivers provided for &os; by installing one of the following ports: The latest versions of nVidia cards are supported by the x11/nvidia-driver port. Older drivers are available as x11/nvidia-driver-### nVidia provides detailed information on which card is supported by which driver on their web site: http://www.nvidia.com/object/IO_32667.html. For Matrox G200/G400, check the x11-servers/mga_hal port. For ATI Rage 128 and Radeon see &man.ati.4x;, &man.r128.4x; and &man.radeon.4x;. Networking Where can I get information on diskless booting? Diskless booting means that the &os; box is booted over a network, and reads the necessary files from a server instead of its hard disk. For full details, see the Handbook entry on diskless booting. Can a &os; box be used as a dedicated network router? Yes. Refer to the Handbook entry on advanced networking, specifically the section on routing and gateways. Can I connect my &windows; box to the Internet via &os;? Typically, people who ask this question have two PCs at home, one with &os; and one with some version of &windows; the idea is to use the &os; box to connect to the Internet and then be able to access the Internet from the &windows; box through the &os; box. This is really just a special case of the previous question and works perfectly well. Dialup users must use and set gateway_enable to YES in /etc/rc.conf. For more information, refer to &man.ppp.8; or the Handbook entry on user PPP. If the connection to the Internet is over Ethernet, use &man.natd.8;. A tutorial can be found in the natd section of the Handbook. Does &os; support PPP? Yes. &man.ppp.8; provides support for both incoming and outgoing connections. For more information on how to use this, refer to the Handbook chapter on PPP. Does &os; support NAT or Masquerading? Yes. For instructions on how to use NAT over a PPP connection, see the Handbook entry on PPP. To use NAT over some other sort of network connection, look at the natd section of the Handbook. How can I set up Ethernet aliases? If the alias is on the same subnet as an address already configured on the interface, add netmask 0xffffffff to this command: &prompt.root; ifconfig ed0 alias 192.0.2.2 netmask 0xffffffff Otherwise, specify the network address and netmask as usual: &prompt.root; ifconfig ed0 alias 172.16.141.5 netmask 0xffffff00 More information can be found in the &os; Handbook. Why can I not NFS-mount from a &linux; box? Some versions of the &linux; NFS code only accept mount requests from a privileged port; try to issue the following command: &prompt.root; mount -o -P linuxbox:/blah /mnt Why does mountd keep telling me it can't change attributes and that I have a bad exports list on my &os; NFS server? The most frequent problem is not understanding the correct format of /etc/exports. Review &man.exports.5; and the NFS entry in the Handbook, especially the section on configuring NFS. How do I enable IP multicast support? Install the net/mrouted package or port and add mrouted_enable="YES" to /etc/rc.conf start this service at boot time. Why do I have to use the FQDN for hosts on my site? See the answer in the &os; Handbook. Why do I get an error, Permission denied, for all networking operations? If the kernel is compiled with the IPFIREWALL option, be aware that the default policy is to deny all packets that are not explicitly allowed. If the firewall is unintentionally misconfigured, restore network operability by typing the following as root: &prompt.root; ipfw add 65534 allow all from any to any Consider setting firewall_type="open" in /etc/rc.conf. For further information on configuring this firewall, see the Handbook chapter. Why is my ipfw fwd rule to redirect a service to another machine not working? Possibly because network address translation (NAT) is needed instead of just forwarding packets. A fwd rule only forwards packets, it does not actually change the data inside the packet. Consider this rule: 01000 fwd 10.0.0.1 from any to foo 21 When a packet with a destination address of foo arrives at the machine with this rule, the packet is forwarded to 10.0.0.1, but it still has the destination address of foo. The destination address of the packet is not changed to 10.0.0.1. Most machines would probably drop a packet that they receive with a destination address that is not their own. Therefore, using a fwd rule does not often work the way the user expects. This behavior is a feature and not a bug. See the FAQ about redirecting services, the &man.natd.8; manual, or one of the several port redirecting utilities in the Ports Collection for a correct way to do this. How can I redirect service requests from one machine to another? FTP and other service requests can be redirected with the sysutils/socket package or port. Replace the entry for the service in /etc/inetd.conf to call socket, as seen in this example for ftpd: ftp stream tcp nowait nobody /usr/local/bin/socket socket ftp.example.com ftp where ftp.example.com and ftp are the host and port to redirect to, respectively. Where can I get a bandwidth management tool? There are three bandwidth management tools available for &os;. &man.dummynet.4; is integrated into &os; as part of &man.ipfw.4;. ALTQ has been integrated into &os; as part of &man.pf.4;. Bandwidth Manager from Emerging Technologies is a commercial product. Why do I get /dev/bpf0: device not configured? The running application requires the Berkeley Packet Filter (&man.bpf.4;), but it was removed from a custom kernel. Add this to the kernel config file and build a new kernel: device bpf # Berkeley Packet Filter How do I mount a disk from a &windows; machine that is on my network, like smbmount in &linux;? Use the SMBFS toolset. It includes a set of kernel modifications and a set of userland programs. The programs and information are available as &man.mount.smbfs.8; in the base system. What are these messages about: Limiting icmp/open port/closed port response in my log files? This kernel message indicates that some activity is provoking it to send a large amount of ICMP or TCP reset (RST) responses. ICMP responses are often generated as a result of attempted connections to unused UDP ports. TCP resets are generated as a result of attempted connections to unopened TCP ports. Among others, these are the kinds of activities which may cause these messages: Brute-force denial of service (DoS) attacks (as opposed to single-packet attacks which exploit a specific vulnerability). Port scans which attempt to connect to a large number of ports (as opposed to only trying a few well-known ports). The first number in the message indicates how many packets the kernel would have sent if the limit was not in place, and the second indicates the limit. This limit is controlled using net.inet.icmp.icmplim. This example sets the limit to 300 packets per second: &prompt.root; sysctl net.inet.icmp.icmplim=300 To disable these messages without disabling response limiting, use net.inet.icmp.icmplim_output to disable the output: &prompt.root; sysctl net.inet.icmp.icmplim_output=0 Finally, to disable response limiting completely, set net.inet.icmp.icmplim to 0. Disabling response limiting is discouraged for the reasons listed above. What are these arp: unknown hardware address format error messages? This means that some device on the local Ethernet is using a MAC address in a format that &os; does not recognize. This is probably caused by someone experimenting with an Ethernet card somewhere else on the network. This is most commonly seen on cable modem networks. It is harmless, and should not affect the performance of the &os; system. Why do I keep seeing messages like: 192.168.0.10 is on fxp1 but got reply from 00:15:17:67:cf:82 on rl0, and how do I disable it? Because a packet is coming from outside the network unexpectedly. To disable them, set net.link.ether.inet.log_arp_wrong_iface to 0. Security What is a sandbox? Sandbox is a security term. It can mean two things: A process which is placed inside a set of virtual walls that are designed to prevent someone who breaks into the process from being able to break into the wider system. The process is only able to run inside the walls. Since nothing the process does in regards to executing code is supposed to be able to breach the walls, a detailed audit of its code is not needed in order to be able to say certain things about its security. The walls might be a user ID, for example. This is the definition used in the &man.security.7; and &man.named.8; man pages. Take the ntalk service, for example (see &man.inetd.8;). This service used to run as user ID root. Now it runs as user ID tty. The tty user is a sandbox designed to make it more difficult for someone who has successfully hacked into the system via ntalk from being able to hack beyond that user ID. A process which is placed inside a simulation of the machine. It means that someone who is able to break into the process may believe that he can break into the wider machine but is, in fact, only breaking into a simulation of that machine and not modifying any real data. The most common way to accomplish this is to build a simulated environment in a subdirectory and then run the processes in that directory chrooted so that / for that process is this directory, not the real / of the system). Another common use is to mount an underlying file system read-only and then create a file system layer on top of it that gives a process a seemingly writeable view into that file system. The process may believe it is able to write to those files, but only the process sees the effects — other processes in the system do not, necessarily. An attempt is made to make this sort of sandbox so transparent that the user (or hacker) does not realize that he is sitting in it. &unix; implements two core sandboxes. One is at the process level, and one is at the userid level. Every &unix; process is completely firewalled off from every other &unix; process. One process cannot modify the address space of another. A &unix; process is owned by a particular userid. If the user ID is not the root user, it serves to firewall the process off from processes owned by other users. The user ID is also used to firewall off on-disk data. What is securelevel? securelevel is a security mechanism implemented in the kernel. When the securelevel is positive, the kernel restricts certain tasks; not even the superuser (root) is allowed to do them. The securelevel mechanism limits the ability to: Unset certain file flags, such as schg (the system immutable flag). Write to kernel memory via /dev/mem and /dev/kmem. Load kernel modules. Alter firewall rules. To check the status of the securelevel on a running system: &prompt.root; sysctl -n kern.securelevel The output contains the current value of the securelevel. If it is greater than 0, at least some of the securelevel's protections are enabled. The securelevel of a running system cannot be lowered as this would defeat its purpose. If a task requires that the securelevel be non-positive, change the kern_securelevel and kern_securelevel_enable variables in /etc/rc.conf and reboot. For more information on securelevel and the specific things all the levels do, consult &man.init.8;. Securelevel is not a silver bullet; it has many known deficiencies. More often than not, it provides a false sense of security. One of its biggest problems is that in order for it to be at all effective, all files used in the boot process up until the securelevel is set must be protected. If an attacker can get the system to execute their code prior to the securelevel being set (which happens quite late in the boot process since some things the system must do at start-up cannot be done at an elevated securelevel), its protections are invalidated. While this task of protecting all files used in the boot process is not technically impossible, if it is achieved, system maintenance will become a nightmare since one would have to take the system down, at least to single-user mode, to modify a configuration file. This point and others are often discussed on the mailing lists, particularly the &a.security;. Search the archives here for an extensive discussion. A more fine-grained mechanism is preferred. - BIND (named) is listening on some + BIND9 + (named) is listening on some high-numbered ports. What is going on? BIND uses a random high-numbered port for outgoing queries. Recent versions of it choose a new, random UDP port for each query. This may cause problems for some network configurations, especially if a firewall blocks incoming UDP packets on particular ports. To get past that firewall, try the avoid-v4-udp-ports and avoid-v6-udp-ports options to avoid selecting random port numbers within a blocked range. If a port number (like 53) is specified via the query-source or query-source-v6 options in - /etc/namedb/named.conf, randomized + /usr/local/etc/namedb/named.conf, + randomized port selection will not be used. It is strongly recommended that these options not be used to specify fixed port numbers. Congratulations, by the way. It is good practice to read &man.sockstat.1; output and notice odd things! The Sendmail daemon is listening on port 587 as well as the standard port 25! What is going on? Recent versions of Sendmail support a mail submission feature that runs over port 587. This is not yet widely supported, but is growing in popularity. What is this UID 0 toor account? Have I been compromised? Do not worry. toor is an alternative superuser account, where toor is root spelled backwards. It is intended to be used with a non-standard shell so the default shell for root does not need to change. This is important as shells which are not part of the base distribution, but are instead installed from ports or packages, are installed in /usr/local/bin which, by default, resides on a different file system. If root's shell is located in /usr/local/bin and the file system containing /usr/local/bin) is not mounted, root will not be able to log in to fix a problem and will have to reboot into single-user mode in order to enter the path to a shell. Some people use toor for day-to-day root tasks with a non-standard shell, leaving root, with a standard shell, for single-user mode or emergencies. By default, a user cannot log in using toor as it does not have a password, so log in as root and set a password for toor before using it to login. PPP I cannot make &man.ppp.8; work. What am I doing wrong? First, read &man.ppp.8; and the PPP section of the Handbook. To assist in troubleshooting, enable logging with the following command: set log Phase Chat Connect Carrier lcp ipcp ccp command This command may be typed at the &man.ppp.8; command prompt or it may be entered at the start of the default section in /etc/ppp/ppp.conf. Make sure that /etc/syslog.conf contains the lines below and the file /var/log/ppp.log exists: !ppp *.* /var/log/ppp.log A lot about what is going can be learned from the log file. Do not worry if it does not all make sense as it may make sense to someone else. Why does &man.ppp.8; hang when I run it? This is usually because the hostname will not resolve. The best way to fix this is to make sure that /etc/hosts is read first by the by ensuring that the hosts line is listed first in /etc/host.conf. Then, put an entry in /etc/hosts for the local machine. If there is no local network, change the localhost line: 127.0.0.1 foo.example.com foo localhost Otherwise, add another entry for the host. Consult the relevant manual pages for more details. When finished, verify that this command is successful: ping -c1 `hostname`. Why will &man.ppp.8; not dial in -auto mode? First, check that a default route exists. This command should display two entries: Destination Gateway Flags Refs Use Netif Expire default 10.0.0.2 UGSc 0 0 tun0 10.0.0.2 10.0.0.1 UH 0 0 tun0 If a default route is not listed, make sure that the HISADDR line has been added to /etc/ppp/ppp.conf. Another reason for the default route line being missing is that a default route has been added to /etc/rc.conf and this line is missing from /etc/ppp/ppp.conf: delete ALL If this is the case, go back to the Final System Configuration section of the Handbook. What does No route to host mean? This error is usually because the following section is missing in /etc/ppp/ppp.linkup: MYADDR: delete ALL add 0 0 HISADDR This is only necessary for a dynamic IP address or when the address of the default gateway is unknown. When using interactive mode, the following can be typed in after entering packet mode. Packet mode is indicated by the capitalized PPP in the prompt: delete ALL add 0 0 HISADDR Refer to the PPP and Dynamic IP addresses section of the Handbook for further details. Why does my connection drop after about 3 minutes? The default PPP timeout is 3 minutes. This can be adjusted with the following line: set timeout NNN where NNN is the number of seconds of inactivity before the connection is closed. If NNN is zero, the connection is never closed due to a timeout. It is possible to put this command in ppp.conf, or to type it at the prompt in interactive mode. It is also possible to adjust it on the fly while the line is active by connecting to ppp's server socket using &man.telnet.1; or &man.pppctl.8;. Refer to the &man.ppp.8; man page for further details. Why does my connection drop under heavy load? If Link Quality Reporting (LQR) is configured, it is possible that too many LQR packets are lost between the &os; system and the peer. &man.ppp.8; deduces that the line must therefore be bad, and disconnects. LQR is disabled by default and can be enabled with the following line: enable lqr Why does my connection drop after a random amount of time? Sometimes, on a noisy phone line or even on a line with call waiting enabled, the modem may hang up because it incorrectly thinks that it lost carrier. There is a setting on most modems for determining how tolerant it should be to temporary losses of carrier. Refer to the modem manual for details. Why does my connection hang after a random amount of time? Many people experience hung connections with no apparent explanation. The first thing to establish is which side of the link is hung. When using an external modem, try using &man.ping.8; to see if the TD light is flashing when data is transmitted. If it flashes but the RD light does not, the problem is with the remote end. If TD does not flash, the problem is local. With an internal modem, use the set server command in ppp.conf. When the hang occurs, connect to &man.ppp.8; using &man.pppctl.8;. If the network connection suddenly revives due to the activity on the diagnostic socket, or if it will not connect but the set socket command succeeded at startup time, the problem is local. If it can connect but things are still hung, enable local logging with set log local async and use &man.ping.8; from another window or terminal to make use of the link. The async logging will show the data being transmitted and received on the link. If data is going out and not coming back, the problem is remote. Having established whether the problem is local or remote, there are now two possibilities: If the problem is remote, read on entry . If the problem is local, read on entry . The remote end is not responding. What can I do? There is very little that can be done about this. Many ISPs will refuse to help users not running a µsoft; OS. Add enable lqr to /etc/ppp/ppp.conf, allowing &man.ppp.8; to detect the remote failure and hang up. This detection is relatively slow and therefore not that useful. First, try disabling all local compression by adding the following to the configuration: disable pred1 deflate deflate24 protocomp acfcomp shortseq vj deny pred1 deflate deflate24 protocomp acfcomp shortseq vj Then reconnect to ensure that this makes no difference. If things improve or if the problem is solved completely, determine which setting makes the difference through trial and error. This is good information for the ISP, although it may make it apparent that it is not a µsoft; system. Before contacting the ISP, enable async logging locally and wait until the connection hangs again. This may use up quite a bit of disk space. The last data read from the port may be of interest. It is usually ASCII data, and may even describe the problem (Memory fault, Core dumped). If the ISP is helpful, they should be able to enable logging on their end, then when the next link drop occurs, they may be able to tell why their side is having a problem. &man.ppp.8; has hung. What can I do? In this case, rebuild &man.ppp.8; with debugging information, and then use &man.gdb.1; to grab a stack trace from the ppp process that is stuck. To rebuild the ppp utility with debugging information, type: &prompt.root; cd /usr/src/usr.sbin/ppp &prompt.root; env DEBUG_FLAGS='-g' make clean &prompt.root; env DEBUG_FLAGS='-g' make install Then, restart ppp and wait until it hangs again. When the debug build of ppp hangs, start gdb on the stuck process by typing: &prompt.root; gdb ppp `pgrep ppp` At the gdb prompt, use the bt or where commands to get a stack trace. Save the output of the gdb session, and detach from the running process by typing quit. I keep seeing errors about magic being the same. What does it mean? Occasionally, just after connecting, there may be messages in the log that say Magic is same. Sometimes, these messages are harmless, and sometimes one side or the other exits. Most PPP implementations cannot survive this problem, and even if the link seems to come up, there will be repeated configure requests and configure acknowledgments in the log file until &man.ppp.8; eventually gives up and closes the connection. This normally happens on server machines with slow disks that are spawning a &man.getty.8; on the port, and executing &man.ppp.8; from a login script or program after login. There were reports of it happening consistently when using slirp. The reason is that in the time taken between &man.getty.8; exiting and &man.ppp.8; starting, the client-side &man.ppp.8; starts sending Line Control Protocol (LCP) packets. Because ECHO is still switched on for the port on the server, the client &man.ppp.8; sees these packets reflect back. One part of the LCP negotiation is to establish a magic number for each side of the link so that reflections can be detected. The protocol says that when the peer tries to negotiate the same magic number, a NAK should be sent and a new magic number should be chosen. During the period that the server port has ECHO turned on, the client &man.ppp.8; sends LCP packets, sees the same magic in the reflected packet and NAKs it. It also sees the NAK reflect (which also means &man.ppp.8; must change its magic). This produces a potentially enormous number of magic number changes, all of which are happily piling into the server's tty buffer. As soon as &man.ppp.8; starts on the server, it is flooded with magic number changes and almost immediately decides it has tried enough to negotiate LCP and gives up. Meanwhile, the client, who no longer sees the reflections, becomes happy just in time to see a hangup from the server. This can be avoided by allowing the peer to start negotiating with the following line in ppp.conf: set openmode passive This tells &man.ppp.8; to wait for the server to initiate LCP negotiations. Some servers however may never initiate negotiations. In this case, try something like: set openmode active 3 This tells &man.ppp.8; to be passive for 3 seconds, and then to start sending LCP requests. If the peer starts sending requests during this period, &man.ppp.8; will immediately respond rather than waiting for the full 3 second period. LCP negotiations continue until the connection is closed. What is wrong? There is currently an implementation mis-feature in &man.ppp.8; where it does not associate LCP, CCP & IPCP responses with their original requests. As a result, if one PPP implementation is more than 6 seconds slower than the other side, the other side will send two additional LCP configuration requests. This is fatal. Consider two implementations, A and B. A starts sending LCP requests immediately after connecting and B takes 7 seconds to start. When B starts, A has sent 3 LCP REQs. We are assuming the line has ECHO switched off, otherwise we would see magic number problems as described in the previous section. B sends a REQ, then an ACK to the first of A's REQs. This results in A entering the OPENED state and sending and ACK (the first) back to B. In the meantime, B sends back two more ACKs in response to the two additional REQs sent by A before B started up. B then receives the first ACK from A and enters the OPENED state. A receives the second ACK from B and goes back to the REQ-SENT state, sending another (forth) REQ as per the RFC. It then receives the third ACK and enters the OPENED state. In the meantime, B receives the forth REQ from A, resulting in it reverting to the ACK-SENT state and sending another (second) REQ and (forth) ACK as per the RFC. A gets the REQ, goes into REQ-SENT and sends another REQ. It immediately receives the following ACK and enters OPENED. This goes on until one side figures out that they are getting nowhere and gives up. The best way to avoid this is to configure one side to be passive — that is, make one side wait for the other to start negotiating. This can be done with the following command: set openmode passive Care should be taken with this option. This command can also be used to limit the amount of time that &man.ppp.8; waits for the peer to begin negotiations: set stopped N Alternatively, the following command (where N is the number of seconds to wait before starting negotiations) can be used: set openmode active N Check the manual page for details. Why does &man.ppp.8; lock up when I shell out to test it? When using shell or !, &man.ppp.8; executes a shell or the passed arguments. The ppp program will wait for the command to complete before continuing. Any attempt to use the PPP link while running the command will appear as a frozen link. This is because &man.ppp.8; is waiting for the command to complete. To execute commands like this, use !bg instead. This will execute the given command in the background, and &man.ppp.8; can continue to service the link. Why does &man.ppp.8; over a null-modem cable never exit? There is no way for &man.ppp.8; to automatically determine that a direct connection has been dropped. This is due to the lines that are used in a null-modem serial cable. When using this sort of connection, LQR should always be enabled with the following line: enable lqr LQR is accepted by default if negotiated by the peer. Why does &man.ppp.8; dial for no reason in mode? If &man.ppp.8; is dialing unexpectedly, determine the cause, and set up dial filters to prevent such dialing. To determine the cause, use the following line: set log +tcp/ip This will log all traffic through the connection. The next time the line comes up unexpectedly, the reason will be logged with a convenient timestamp next to it. Next, disable dialing under these circumstances. Usually, this sort of problem arises due to DNS lookups. To prevent DNS lookups from establishing a connection (this will not prevent &man.ppp.8; from passing the packets through an established connection), use the following: set dfilter 1 deny udp src eq 53 set dfilter 2 deny udp dst eq 53 set dfilter 3 permit 0/0 0/0 This is not always suitable, as it will effectively break demand-dial capabilities. Most programs will need a DNS lookup before doing any other network related things. In the DNS case, try to determine what is actually trying to resolve a host name. A lot of the time, Sendmail is the culprit. Make sure to configure Sendmail not to do any DNS lookups in its configuration file. See the section on using email with a dialup connection in the &os; Handbook for details. You may also want to add the following line to .mc: define(`confDELIVERY_MODE', `d')dnl This will make Sendmail queue everything until the queue is run, usually, every 30 minutes, or until a sendmail -q is done, perhaps from /etc/ppp/ppp.linkup. What do these CCP errors mean? I keep seeing the following errors in my log file: CCP: CcpSendConfigReq CCP: Received Terminate Ack (1) state = Req-Sent (6) This is because &man.ppp.8; is trying to negotiate Predictor1 compression, but the peer does not want to negotiate any compression at all. The messages are harmless, but can be silenced by disabling the compression: disable pred1 Why does &man.ppp.8; not log my connection speed? To log all lines of the modem conversation, enable the following: set log +connect This will make &man.ppp.8; log everything up until the last requested expect string. To see the connect speed when using PAP or CHAP, make sure to configure &man.ppp.8; to expect the whole CONNECT line, using something like this: set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 4 \ \"\" ATZ OK-ATZ-OK ATDT\\T TIMEOUT 60 CONNECT \\c \\n" This gets the CONNECT, sends nothing, then expects a line-feed, forcing &man.ppp.8; to read the whole CONNECT response. Why does &man.ppp.8; ignore the \ character in my chat script? The ppp utility parses each line in its configuration files so that it can interpret strings such as set phone "123 456 789" correctly and realize that the number is actually only one argument. To specify a " character, escape it using a backslash (\). When the chat interpreter parses each argument, it re-interprets the argument to find any special escape sequences such as \P or \T. As a result of this double-parsing, remember to use the correct number of escapes. To actually send a \ character, do something like: set dial "\"\" ATZ OK-ATZ-OK AT\\\\X OK" It will result in the following sequence: ATZ OK AT\X OK Or: set phone 1234567 set dial "\"\" ATZ OK ATDT\\T" It will result in the following sequence: ATZ OK ATDT1234567 What are FCS errors? FCS stands for Frame Check Sequence. Each PPP packet has a checksum attached to ensure that the data being received is the data being sent. If the FCS of an incoming packet is incorrect, the packet is dropped and the HDLC FCS count is increased. The HDLC error values can be displayed using the show hdlc command. If the link is bad or if the serial driver is dropping packets, it will produce the occasional FCS error. This is not usually worth worrying about although it does slow down the compression protocols substantially. If the link freezes as soon as it connects and produces a large number of FCS errors, make sure the modem is not using software flow control (XON/XOFF). If the link must use software flow control, use set accmap 0x000a0000 to tell &man.ppp.8; to escape the ^Q and ^S characters. Another reason for too many FCS errors may be that the remote end has stopped talking PPP. In this case, enable async logging to determine if the incoming data is actually a login or shell prompt. If it is a shell prompt at the remote end, it is possible to terminate &man.ppp.8; without dropping the line by using close lcp followed by term) to reconnect to the shell on the remote machine. If nothing in the log file indicates why the link was terminated, ask the remote administrator or ISP why the session was terminated. None of this helps — I am desperate! What can I do? If all else fails, send the details of the error, the configuration files, how &man.ppp.8; is being started, the relevant parts of the log file, and the output of netstat -rn, before and after connecting, to the &a.questions;. Serial Communications This section answers common questions about serial communications with &os;. PPP is covered in the Networking section. Which multi-port serial cards are supported by &os;? There is a list of these in the Serial Communications chapter of the Handbook. Most multi-port PCI cards that are based on 16550 or clones are supported with no extra effort. Some unnamed clone cards have also been known to work, especially those that claim to be AST compatible. Check &man.uart.4; and &man.sio.4; to get more information on configuring such cards. How do I get the boot: prompt to show on the serial console? See this section of the Handbook. How do I tell if &os; found my serial ports or modem cards? As the &os; kernel boots, it will probe for the serial ports for which the kernel is configured. Either watch the boot messages closely or run this command after the system is up and running: &prompt.user; dmesg | grep -E "^sio[0-9]" sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0 sio0: type 16550A sio1: <16550A-compatible COM port> port 0x2f8-0x2ff irq 3 on acpi0 sio1: type 16550A This example shows two serial ports. The first is on IRQ4, port address 0x3f8, and has a 16550A-type UART chip. The second uses the same kind of chip but is on IRQ3 and is at port address 0x2f8. Internal modem cards are treated just like serial ports, except that they always have a modem attached to the port. The GENERIC kernel includes support for two serial ports using the same IRQ and port address settings in the above example. If these settings are not right for the system, or if there are more modem cards or serial ports than the kernel is configured for, reconfigure using the instructions in building a kernel for more details. How do I access the serial ports on &os;? The third serial port, sio2, or COM3, is on /dev/cuad2 for dial-out devices, and on /dev/ttyd2 for dial-in devices. What is the difference between these two classes of devices? When opening /dev/ttydX in blocking mode, a process will wait for the corresponding cuadX device to become inactive, and then wait for the carrier detect line to go active. When the cuadX device is opened, it makes sure the serial port is not already in use by the ttydX device. If the port is available, it steals it from the ttydX device. Also, the cuadX device does not care about carrier detect. With this scheme and an auto-answer modem, remote users can log in and local users can still dial out with the same modem and the system will take care of all the conflicts. How do I enable support for a multi-port serial card? The section on kernel configuration provides information about configuring the kernel. For a multi-port serial card, place an &man.sio.4; line for each serial port on the card in the &man.device.hints.5; file. But place the IRQ specifiers on only one of the entries. All of the ports on the card should share one IRQ. For consistency, use the last serial port to specify the IRQ. Also, specify the following option in the kernel configuration file: options COM_MULTIPORT The following /boot/device.hints example is for an AST 4-port serial card on IRQ 12: hint.sio.4.at="isa" hint.sio.4.port="0x2a0" hint.sio.4.flags="0x701" hint.sio.5.at="isa" hint.sio.5.port="0x2a8" hint.sio.5.flags="0x701" hint.sio.6.at="isa" hint.sio.6.port="0x2b0" hint.sio.6.flags="0x701" hint.sio.7.at="isa" hint.sio.7.port="0x2b8" hint.sio.7.flags="0x701" hint.sio.7.irq="12" The flags indicate that the master port has minor number 7 (0x700), and all the ports share an IRQ (0x001). Can I set the default serial parameters for a port? See the Serial Communications section in the &os; Handbook. How can I enable dialup logins on my modem? Refer to the section about Dial-in Services in the &os; Handbook. How can I connect a dumb terminal to my &os; box? This information is in the Terminals section of the &os; Handbook. Why can I not run tip or cu? The built-in &man.tip.1; and &man.cu.1; utilities can only access the /var/spool/lock directory via user uucp and group dialer. Use the dialer group to control who has access to the modem or remote systems by adding user accounts to dialer. Alternatively, everyone can be configured to run &man.tip.1; and &man.cu.1; by typing: &prompt.root; chmod 4511 /usr/bin/cu &prompt.root; chmod 4511 /usr/bin/tip Miscellaneous Questions &os; uses a lot of swap space even when the computer has free memory left. Why? &os; will proactively move entirely idle, unused pages of main memory into swap in order to make more main memory available for active use. This heavy use of swap is balanced by using the extra free memory for caching. Note that while &os; is proactive in this regard, it does not arbitrarily decide to swap pages when the system is truly idle. Thus, the system will not be all paged out after leaving it idle overnight. Why does top show very little free memory even when I have very few programs running? The simple answer is that free memory is wasted memory. Any memory that programs do not actively allocate is used within the &os; kernel as disk cache. The values shown by &man.top.1; labeled as Inact, Cache, and Buf are all cached data at different aging levels. This cached data means the system does not have to access a slow disk again for data it has accessed recently, thus increasing overall performance. In general, a low value shown for Free memory in &man.top.1; is good, provided it is not very low. Why will chmod not change the permissions on symlinks? Symlinks do not have permissions, and by default, &man.chmod.1; will follow symlinks to change the permissions on the source file, if possible. For the file, foo with a symlink named bar, this command will always succeed. &prompt.user; chmod g-w bar However, the permissions on bar will not have changed. When changing modes of the file hierarchies rooted in the files instead of the files themselves, use either or together with to make this work. See &man.chmod.1; and &man.symlink.7; for more information. does a recursive &man.chmod.1;. Be careful about specifying directories or symlinks to directories to &man.chmod.1;. To change the permissions of a directory referenced by a symlink, use &man.chmod.1; without any options and follow the symlink with a trailing slash (/). For example, if foo is a symlink to directory bar, to change the permissions of foo (actually bar), do something like: &prompt.user; chmod 555 foo/ With the trailing slash, &man.chmod.1; will follow the symlink, foo, to change the permissions of the directory, bar. Can I run DOS binaries under &os;? Yes. A DOS emulation program, emulators/doscmd, is available in the &os; Ports Collection. If doscmd will not suffice, emulators/pcemu emulates an 8088 and enough BIOS services to run many DOS text-mode applications. It requires the X Window System. The Ports Collection also has emulators/dosbox. The main focus of this application is emulating old DOS games using the local file system for files. What do I need to do to translate a &os; document into my native language? See the Translation FAQ in the &os; Documentation Project Primer. Why does my email to any address at FreeBSD.org bounce? The FreeBSD.org mail system implements some Postfix checks on incoming mail and rejects mail that is either from misconfigured relays or otherwise appears likely to be spam. Some of the specific requirements are: The IP address of the SMTP client must "reverse-resolve" to a forward confirmed hostname. The fully-qualified hostname given in the SMTP conversation (either HELO or EHLO) must resolve to the IP address of the client. Other advice to help mail reach its destination include: Mail should be sent in plain text, and messages sent to mailing lists should generally be no more than 200KB in length. Avoid excessive cross posting. Choose one mailing list which seems most relevant and send it there. If you still have trouble with email infrastructure at FreeBSD.org, send a note with the details to postmaster@freebsd.org; Include a date/time interval so that logs may be reviewed — and note that we only keep one week's worth of mail logs. (Be sure to specify the time zone or offset from UTC.) Where can I find a free &os; account? While &os; does not provide open access to any of their servers, others do provide open access &unix; systems. The charge varies and limited services may be available. Arbornet, Inc, also known as M-Net, has been providing open access to &unix; systems since 1983. Starting on an Altos running System III, the site switched to BSD/OS in 1991. In June of 2000, the site switched again to &os;. M-Net can be accessed via telnet and SSH and provides basic access to the entire &os; software suite. However, network access is limited to members and patrons who donate to the system, which is run as a non-profit organization. M-Net also provides an bulletin board system and interactive chat. What is the cute little red guy's name? He does not have one, and is just called the BSD daemon. If you insist upon using a name, call him beastie. Note that beastie is pronounced BSD. More about the BSD daemon is available on his home page. Can I use the BSD daemon image? Perhaps. The BSD daemon is copyrighted by Marshall Kirk McKusick. Check his Statement on the Use of the BSD Daemon Figure for detailed usage terms. In summary, the image can be used in a tasteful manner, for personal use, so long as appropriate credit is given. Before using the logo commercially, contact &a.mckusick.email; for permission. More details are available on the BSD Daemon's home page. Do you have any BSD daemon images I could use? Xfig and eps drawings are available under /usr/share/examples/BSD_daemon/. I have seen an acronym or other term on the mailing lists and I do not understand what it means. Where should I look? Refer to the &os; Glossary. Why should I care what color the bikeshed is? The really, really short answer is that you should not. The somewhat longer answer is that just because you are capable of building a bikeshed does not mean you should stop others from building one just because you do not like the color they plan to paint it. This is a metaphor indicating that you need not argue about every little feature just because you know enough to do so. Some people have commented that the amount of noise generated by a change is inversely proportional to the complexity of the change. The longer and more complete answer is that after a very long argument about whether &man.sleep.1; should take fractional second arguments, &a.phk.email; posted a long message entitled A bike shed (any color will do) on greener grass.... The appropriate portions of that message are quoted below.
&a.phk.email; on &a.hackers.name;, October 2, 1999 What is it about this bike shed? Some of you have asked me. It is a long story, or rather it is an old story, but it is quite short actually. C. Northcote Parkinson wrote a book in the early 1960s, called Parkinson's Law, which contains a lot of insight into the dynamics of management. [snip a bit of commentary on the book] In the specific example involving the bike shed, the other vital component is an atomic power-plant, I guess that illustrates the age of the book. Parkinson shows how you can go into the board of directors and get approval for building a multi-million or even billion dollar atomic power plant, but if you want to build a bike shed you will be tangled up in endless discussions. Parkinson explains that this is because an atomic plant is so vast, so expensive and so complicated that people cannot grasp it, and rather than try, they fall back on the assumption that somebody else checked all the details before it got this far. Richard P. Feynmann gives a couple of interesting, and very much to the point, examples relating to Los Alamos in his books. A bike shed on the other hand. Anyone can build one of those over a weekend, and still have time to watch the game on TV. So no matter how well prepared, no matter how reasonable you are with your proposal, somebody will seize the chance to show that he is doing his job, that he is paying attention, that he is here. In Denmark we call it setting your fingerprint. It is about personal pride and prestige, it is about being able to point somewhere and say There! I did that. It is a strong trait in politicians, but present in most people given the chance. Just think about footsteps in wet cement.
The &os; Funnies How cool is &os;? Q. Has anyone done any temperature testing while running &os;? I know &linux; runs cooler than DOS, but have never seen a mention of &os;. It seems to run really hot. A. No, but we have done numerous taste tests on blindfolded volunteers who have also had 250 micrograms of LSD-25 administered beforehand. 35% of the volunteers said that &os; tasted sort of orange, whereas &linux; tasted like purple haze. Neither group mentioned any significant variances in temperature. We eventually had to throw the results of this survey out entirely anyway when we found that too many volunteers were wandering out of the room during the tests, thus skewing the results. We think most of the volunteers are at Apple now, working on their new scratch and sniff GUI. It is a funny old business we are in! Seriously, &os; uses the HLT (halt) instruction when the system is idle thus lowering its energy consumption and therefore the heat it generates. Also if you have ACPI (Advanced Configuration and Power Interface) configured, then &os; can also put the CPU into a low power mode. Who is scratching in my memory banks?? Q. Is there anything odd that &os; does when compiling the kernel which would cause the memory to make a scratchy sound? When compiling (and for a brief moment after recognizing the floppy drive upon startup, as well), a strange scratchy sound emanates from what appears to be the memory banks. A. Yes! You will see frequent references to daemons in the BSD documentation, and what most people do not know is that this refers to genuine, non-corporeal entities that now possess your computer. The scratchy sound coming from your memory is actually high-pitched whispering exchanged among the daemons as they best decide how to deal with various system administration tasks. If the noise gets to you, a good fdisk /mbr from DOS will get rid of them, but do not be surprised if they react adversely and try to stop you. In fact, if at any point during the exercise you hear the satanic voice of Bill Gates coming from the built-in speaker, take off running and do not ever look back! Freed from the counterbalancing influence of the BSD daemons, the twin demons of DOS and &windows; are often able to re-assert total control over your machine to the eternal damnation of your soul. Now that you know, given a choice you would probably prefer to get used to the scratchy noises, no? How many &os; hackers does it take to change a lightbulb? One thousand, one hundred and sixty-nine: Twenty-three to complain to -CURRENT about the lights being out; Four to claim that it is a configuration problem, and that such matters really belong on -questions; Three to submit PRs about it, one of which is misfiled under doc and consists only of it's dark; One to commit an untested lightbulb which breaks buildworld, then back it out five minutes later; Eight to flame the PR originators for not including patches in their PRs; Five to complain about buildworld being broken; Thirty-one to answer that it works for them, and they must have updated at a bad time; One to post a patch for a new lightbulb to -hackers; One to complain that he had patches for this three years ago, but when he sent them to -CURRENT they were just ignored, and he has had bad experiences with the PR system; besides, the proposed new lightbulb is non-reflexive; Thirty-seven to scream that lightbulbs do not belong in the base system, that committers have no right to do things like this without consulting the Community, and WHAT IS -CORE DOING ABOUT IT!? Two hundred to complain about the color of the bicycle shed; Three to point out that the patch breaks &man.style.9;; Seventeen to complain that the proposed new lightbulb is under GPL; Five hundred and eighty-six to engage in a flame war about the comparative advantages of the GPL, the BSD license, the MIT license, the NPL, and the personal hygiene of unnamed FSF founders; Seven to move various portions of the thread to -chat and -advocacy; One to commit the suggested lightbulb, even though it shines dimmer than the old one; Two to back it out with a furious flame of a commit message, arguing that &os; is better off in the dark than with a dim lightbulb; Forty-six to argue vociferously about the backing out of the dim lightbulb and demanding a statement from -core; Eleven to request a smaller lightbulb so it will fit their Tamagotchi if we ever decide to port &os; to that platform; Seventy-three to complain about the SNR on -hackers and -chat and unsubscribe in protest; Thirteen to post unsubscribe, How do I unsubscribe?, or Please remove me from the list, followed by the usual footer; One to commit a working lightbulb while everybody is too busy flaming everybody else to notice; Thirty-one to point out that the new lightbulb would shine 0.364% brighter if compiled with TenDRA (although it will have to be reshaped into a cube), and that &os; should therefore switch to TenDRA instead of GCC; One to complain that the new lightbulb lacks fairings; Nine (including the PR originators) to ask what is MFC?; Fifty-seven to complain about the lights being out two weeks after the bulb has been changed. &a.nik.email; adds: I was laughing quite hard at this. And then I thought, Hang on, shouldn't there be '1 to document it.' in that list somewhere? And then I was enlightened :-) &a.tabthorpe.email; says: None, real &os; hackers are not afraid of the dark! Where does data written to /dev/null go? It goes into a special data sink in the CPU where it is converted to heat which is vented through the heatsink / fan assembly. This is why CPU cooling is increasingly important; as people get used to faster processors, they become careless with their data and more and more of it ends up in /dev/null, overheating their CPUs. If you delete /dev/null (which effectively disables the CPU data sink) your CPU may run cooler but your system will quickly become constipated with all that excess data and start to behave erratically. If you have a fast network connection you can cool down your CPU by reading data out of /dev/random and sending it off somewhere; however you run the risk of overheating your network connection and / or angering your ISP, as most of the data will end up getting converted to heat by their equipment, but they generally have good cooling, so if you do not overdo it you should be OK. Paul Robinson adds: There are other methods. As every good sysadmin knows, it is part of standard practice to send data to the screen of interesting variety to keep all the pixies that make up your picture happy. Screen pixies (commonly mis-typed or re-named as pixels) are categorized by the type of hat they wear (red, green or blue) and will hide or appear (thereby showing the color of their hat) whenever they receive a little piece of food. Video cards turn data into pixie-food, and then send them to the pixies — the more expensive the card, the better the food, so the better behaved the pixies are. They also need constant stimulation — this is why screen savers exist. To take your suggestions further, you could just throw the random data to console, thereby letting the pixies consume it. This causes no heat to be produced at all, keeps the pixies happy and gets rid of your data quite quickly, even if it does make things look a bit messy on your screen. Incidentally, as an ex-admin of a large ISP who experienced many problems attempting to maintain a stable temperature in a server room, I would strongly discourage people sending the data they do not want out to the network. The fairies who do the packet switching and routing get annoyed by it as well. My colleague sits at the computer too much, how can I prank her? Install games/sl and wait for her to mistype sl for ls. Advanced Topics How can I learn more about &os;'s internals? See the &os; Architecture Handbook. Additionally, much general &unix; knowledge is directly applicable to &os;. How can I contribute to &os;? See the article on Contributing to &os; for specific advice on how to do this. Assistance is more than welcome! What are snapshots and releases? There are currently &rel.numbranch; active/semi-active branches in the &os; Subversion Repository. (Earlier branches are only changed very rarely, which is why there are only &rel.numbranch; active branches of development): &rel2.releng; AKA &rel2.stable; &rel.releng; AKA &rel.stable; &rel.head.releng; AKA -CURRENT AKA &rel.head; HEAD is not an actual branch tag. It is a symbolic constant for the current, non-branched development stream known as -CURRENT. Right now, -CURRENT is the &rel.head.relx; development stream; the &rel.stable; branch, &rel.releng;, forked off from -CURRENT in &rel.relengdate; and the &rel2.stable; branch, &rel2.releng;, forked off from -CURRENT in &rel2.relengdate;. I have written a kernel extension, who do I send it to? Take a look at the article on Contributing to &os; to learn how to submit code. And thanks for the thought! How can I make the most of the data I see when my kernel panics? Here is typical kernel panic: Fatal trap 12: page fault while in kernel mode fault virtual address = 0x40 fault code = supervisor read, page not present instruction pointer = 0x8:0xf014a7e5 stack pointer = 0x10:0xf4ed6f24 frame pointer = 0x10:0xf4ed6f28 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, def32 1, gran 1 processor eflags = interrupt enabled, resume, IOPL = 0 current process = 80 (mount) interrupt mask = trap number = 12 panic: page fault This message is not enough. While the instruction pointer value is important, it is also configuration dependent as it varies depending on the kernel image. If it is a GENERIC kernel image from one of the snapshots, it is possible for somebody else to track down the offending function, but for a custom kernel, only you can tell us where the fault occurred. To proceed: Write down the instruction pointer value. Note that the 0x8: part at the beginning is not significant in this case: it is the 0xf0xxxxxx part that we want. When the system reboots, do the following: &prompt.user; nm -n kernel.that.caused.the.panic | grep f0xxxxxx where f0xxxxxx is the instruction pointer value. The odds are you will not get an exact match since the symbols in the kernel symbol table are for the entry points of functions and the instruction pointer address will be somewhere inside a function, not at the start. If you do not get an exact match, omit the last digit from the instruction pointer value and try again: &prompt.user; nm -n kernel.that.caused.the.panic | grep f0xxxxx If that does not yield any results, chop off another digit. Repeat until there is some sort of output. The result will be a possible list of functions which caused the panic. This is a less than exact mechanism for tracking down the point of failure, but it is better than nothing. However, the best way to track down the cause of a panic is by capturing a crash dump, then using &man.kgdb.1; to generate a stack trace on the crash dump. In any case, the method is this: Make sure that the following line is included in the kernel configuration file: makeoptions DEBUG=-g # Build kernel with gdb(1) debug symbols Change to the /usr/src directory: &prompt.root; cd /usr/src Compile the kernel: &prompt.root; make buildkernel KERNCONF=MYKERNEL Wait for &man.make.1; to finish compiling. &prompt.root; make installkernel KERNCONF=MYKERNEL Reboot. If KERNCONF is not included, the GENERIC kernel will instead be built and installed. The &man.make.1; process will have built two kernels. /usr/obj/usr/src/sys/MYKERNEL/kernel and /usr/obj/usr/src/sys/MYKERNEL/kernel.debug. kernel was installed as /boot/kernel/kernel, while kernel.debug can be used as the source of debugging symbols for &man.kgdb.1;. To capture a crash dump, edit /etc/rc.conf and set dumpdev to point to either the swap partition or AUTO. This will cause the &man.rc.8; scripts to use the &man.dumpon.8; command to enable crash dumps. This command can also be run manually. After a panic, the crash dump can be recovered using &man.savecore.8;; if dumpdev is set in /etc/rc.conf, the &man.rc.8; scripts will run &man.savecore.8; automatically and put the crash dump in /var/crash. &os; crash dumps are usually the same size as physical RAM. Therefore, make sure there is enough space in /var/crash to hold the dump. Alternatively, run &man.savecore.8; manually and have it recover the crash dump to another directory with more room. It is possible to limit the size of the crash dump by using options MAXMEM=N where N is the size of kernel's memory usage in KBs. For example, for 1 GB of RAM, limit the kernel's memory usage to 128 MB, so that the crash dump size will be 128 MB instead of 1 GB. Once the crash dump has been recovered , get a stack trace as follows: &prompt.user; kgdb /usr/obj/usr/src/sys/MYKERNEL/kernel.debug /var/crash/vmcore.0 (kgdb) backtrace Note that there may be several screens worth of information. Ideally, use &man.script.1; to capture all of them. Using the unstripped kernel image with all the debug symbols should show the exact line of kernel source code where the panic occurred. The stack trace is usually read from the bottom up to trace the exact sequence of events that lead to the crash. &man.kgdb.1; can also be used to print out the contents of various variables or structures to examine the system state at the time of the crash. If a second computer is available, &man.kgdb.1; can be configured to do remote debugging, including setting breakpoints and single-stepping through the kernel code. If DDB is enabled and the kernel drops into the debugger, a panic and a crash dump can be forced by typing panic at the ddb prompt. It may stop in the debugger again during the panic phase. If it does, type continue and it will finish the crash dump. Why has dlsym() stopped working for ELF executables? The ELF toolchain does not, by default, make the symbols defined in an executable visible to the dynamic linker. Consequently dlsym() searches on handles obtained from calls to dlopen(NULL, flags) will fail to find such symbols. To search, using dlsym(), for symbols present in the main executable of a process, link the executable using the option to the ELF linker (&man.ld.1;). How can I increase or reduce the kernel address space on i386? By default, the kernel address space is 1 GB (2 GB for PAE) for i386. When running a network-intensive server or using ZFS, this will probably not be enough. Add the following line to the kernel configuration file to increase available space and rebuild the kernel: options KVA_PAGES=N To find the correct value of N, divide the desired address space size (in megabytes) by four. (For example, it is 512 for 2 GB.) Acknowledgments This innocent little Frequently Asked Questions document has been written, rewritten, edited, folded, spindled, mutilated, eviscerated, contemplated, discombobulated, cogitated, regurgitated, rebuilt, castigated, and reinvigorated over the last decade, by a cast of hundreds if not thousands. Repeatedly. We wish to thank every one of the people responsible, and we encourage you to join them in making this FAQ even better. &bibliography; Index: head/en_US.ISO8859-1/books/handbook/basics/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/basics/chapter.xml (revision 51389) +++ head/en_US.ISO8859-1/books/handbook/basics/chapter.xml (revision 51390) @@ -1,3410 +1,3405 @@ &os; Basics Synopsis This chapter covers the basic commands and functionality of the &os; operating system. Much of this material is relevant for any &unix;-like operating system. New &os; users are encouraged to read through this chapter carefully. After reading this chapter, you will know: How to use and configure virtual consoles. How to create and manage users and groups on &os;. How &unix; file permissions and &os; file flags work. The default &os; file system layout. The &os; disk organization. How to mount and unmount file systems. What processes, daemons, and signals are. What a shell is, and how to change the default login environment. How to use basic text editors. What devices and device nodes are. How to read manual pages for more information. Virtual Consoles and Terminals virtual consoles terminals console Unless &os; has been configured to automatically start a graphical environment during startup, the system will boot into a command line login prompt, as seen in this example: FreeBSD/amd64 (pc3.example.org) (ttyv0) login: The first line contains some information about the system. The amd64 indicates that the system in this example is running a 64-bit version of &os;. The hostname is pc3.example.org, and ttyv0 indicates that this is the system console. The second line is the login prompt. Since &os; is a multiuser system, it needs some way to distinguish between different users. This is accomplished by requiring every user to log into the system before gaining access to the programs on the system. Every user has a unique name username and a personal password. To log into the system console, type the username that was configured during system installation, as described in , and press Enter. Then enter the password associated with the username and press Enter. The password is not echoed for security reasons. Once the correct password is input, the message of the day (MOTD) will be displayed followed by a command prompt. Depending upon the shell that was selected when the user was created, this prompt will be a #, $, or % character. The prompt indicates that the user is now logged into the &os; system console and ready to try the available commands. Virtual Consoles While the system console can be used to interact with the system, a user working from the command line at the keyboard of a &os; system will typically instead log into a virtual console. This is because system messages are configured by default to display on the system console. These messages will appear over the command or file that the user is working on, making it difficult to concentrate on the work at hand. By default, &os; is configured to provide several virtual consoles for inputting commands. Each virtual console has its own login prompt and shell and it is easy to switch between virtual consoles. This essentially provides the command line equivalent of having several windows open at the same time in a graphical environment. The key combinations AltF1 through AltF8 have been reserved by &os; for switching between virtual consoles. Use AltF1 to switch to the system console (ttyv0), AltF2 to access the first virtual console (ttyv1), AltF3 to access the second virtual console (ttyv2), and so on. When switching from one console to the next, &os; manages the screen output. The result is an illusion of having multiple virtual screens and keyboards that can be used to type commands for &os; to run. The programs that are launched in one virtual console do not stop running when the user switches to a different virtual console. Refer to &man.kbdcontrol.1;, &man.vidcontrol.1;, &man.atkbd.4;, &man.syscons.4;, and &man.vt.4; for a more technical description of the &os; console and its keyboard drivers. In &os;, the number of available virtual consoles is configured in this section of /etc/ttys: # name getty type status comments # ttyv0 "/usr/libexec/getty Pc" xterm on secure # Virtual terminals ttyv1 "/usr/libexec/getty Pc" xterm on secure ttyv2 "/usr/libexec/getty Pc" xterm on secure ttyv3 "/usr/libexec/getty Pc" xterm on secure ttyv4 "/usr/libexec/getty Pc" xterm on secure ttyv5 "/usr/libexec/getty Pc" xterm on secure ttyv6 "/usr/libexec/getty Pc" xterm on secure ttyv7 "/usr/libexec/getty Pc" xterm on secure ttyv8 "/usr/X11R6/bin/xdm -nodaemon" xterm off secure To disable a virtual console, put a comment symbol (#) at the beginning of the line representing that virtual console. For example, to reduce the number of available virtual consoles from eight to four, put a # in front of the last four lines representing virtual consoles ttyv5 through ttyv8. Do not comment out the line for the system console ttyv0. Note that the last virtual console (ttyv8) is used to access the graphical environment if &xorg; has been installed and configured as described in . For a detailed description of every column in this file and the available options for the virtual consoles, refer to &man.ttys.5;. Single User Mode The &os; boot menu provides an option labelled as Boot Single User. If this option is selected, the system will boot into a special mode known as single user mode. This mode is typically used to repair a system that will not boot or to reset the root password when it is not known. While in single user mode, networking and other virtual consoles are not available. However, full root access to the system is available, and by default, the root password is not needed. For these reasons, physical access to the keyboard is needed to boot into this mode and determining who has physical access to the keyboard is something to consider when securing a &os; system. The settings which control single user mode are found in this section of /etc/ttys: # name getty type status comments # # If console is marked "insecure", then init will ask for the root password # when going to single-user mode. console none unknown off secure By default, the status is set to secure. This assumes that who has physical access to the keyboard is either not important or it is controlled by a physical security policy. If this setting is changed to insecure, the assumption is that the environment itself is insecure because anyone can access the keyboard. When this line is changed to insecure, &os; will prompt for the root password when a user selects to boot into single user mode. Be careful when changing this setting to insecure! If the root password is forgotten, booting into single user mode is still possible, but may be difficult for someone who is not familiar with the &os; booting process. Changing Console Video Modes The &os; console default video mode may be adjusted to 1024x768, 1280x1024, or any other size supported by the graphics chip and monitor. To use a different video mode load the VESA module: &prompt.root; kldload vesa To determine which video modes are supported by the hardware, use &man.vidcontrol.1;. To get a list of supported video modes issue the following: &prompt.root; vidcontrol -i mode The output of this command lists the video modes that are supported by the hardware. To select a new video mode, specify the mode using &man.vidcontrol.1; as the root user: &prompt.root; vidcontrol MODE_279 If the new video mode is acceptable, it can be permanently set on boot by adding it to /etc/rc.conf: allscreens_flags="MODE_279" Users and Basic Account Management &os; allows multiple users to use the computer at the same time. While only one user can sit in front of the screen and use the keyboard at any one time, any number of users can log in to the system through the network. To use the system, each user should have their own user account. This chapter describes: The different types of user accounts on a &os; system. How to add, remove, and modify user accounts. How to set limits to control the resources that users and groups are allowed to access. How to create groups and add users as members of a group. Account Types Since all access to the &os; system is achieved using accounts and all processes are run by users, user and account management is important. There are three main types of accounts: system accounts, user accounts, and the superuser account. System Accounts accounts system System accounts are used to run services such as DNS, mail, and web servers. The reason for this is security; if all services ran as the superuser, they could act without restriction. accounts daemon accounts operator Examples of system accounts are daemon, operator, bind, news, and www. accounts nobody nobody is the generic unprivileged system account. However, the more services that use nobody, the more files and processes that user will become associated with, and hence the more privileged that user becomes. User Accounts accounts user User accounts are assigned to real people and are used to log in and use the system. Every person accessing the system should have a unique user account. This allows the administrator to find out who is doing what and prevents users from clobbering the settings of other users. Each user can set up their own environment to accommodate their use of the system, by configuring their default shell, editor, key bindings, and language settings. Every user account on a &os; system has certain information associated with it: User name The user name is typed at the login: prompt. Each user must have a unique user name. There are a number of rules for creating valid user names which are documented in &man.passwd.5;. It is recommended to use user names that consist of eight or fewer, all lower case characters in order to maintain backwards compatibility with applications. Password Each account has an associated password. User ID (UID) The User ID (UID) is a number used to uniquely identify the user to the &os; system. Commands that allow a user name to be specified will first convert it to the UID. It is recommended to use a UID less than 65535, since higher values may cause compatibility issues with some software. Group ID (GID) The Group ID (GID) is a number used to uniquely identify the primary group that the user belongs to. Groups are a mechanism for controlling access to resources based on a user's GID rather than their UID. This can significantly reduce the size of some configuration files and allows users to be members of more than one group. It is recommended to use a GID of 65535 or lower as higher GIDs may break some software. Login class Login classes are an extension to the group mechanism that provide additional flexibility when tailoring the system to different users. Login classes are discussed further in . Password change time By default, passwords do not expire. However, password expiration can be enabled on a per-user basis, forcing some or all users to change their passwords after a certain amount of time has elapsed. Account expiration time By default, &os; does not expire accounts. When creating accounts that need a limited lifespan, such as student accounts in a school, specify the account expiry date using &man.pw.8;. After the expiry time has elapsed, the account cannot be used to log in to the system, although the account's directories and files will remain. User's full name The user name uniquely identifies the account to &os;, but does not necessarily reflect the user's real name. Similar to a comment, this information can contain spaces, uppercase characters, and be more than 8 characters long. Home directory The home directory is the full path to a directory on the system. This is the user's starting directory when the user logs in. A common convention is to put all user home directories under /home/username or /usr/home/username. Each user stores their personal files and subdirectories in their own home directory. User shell The shell provides the user's default environment for interacting with the system. There are many different kinds of shells and experienced users will have their own preferences, which can be reflected in their account settings. The Superuser Account accounts superuser (root) The superuser account, usually called root, is used to manage the system with no limitations on privileges. For this reason, it should not be used for day-to-day tasks like sending and receiving mail, general exploration of the system, or programming. The superuser, unlike other user accounts, can operate without limits, and misuse of the superuser account may result in spectacular disasters. User accounts are unable to destroy the operating system by mistake, so it is recommended to login as a user account and to only become the superuser when a command requires extra privilege. Always double and triple-check any commands issued as the superuser, since an extra space or missing character can mean irreparable data loss. There are several ways to gain superuser privilege. While one can log in as root, this is highly discouraged. Instead, use &man.su.1; to become the superuser. If - is specified when running this command, the user will also inherit the root user's environment. The user running this command must be in the wheel group or else the command will fail. The user must also know the password for the root user account. In this example, the user only becomes superuser in order to run make install as this step requires superuser privilege. Once the command completes, the user types exit to leave the superuser account and return to the privilege of their user account. Install a Program As the Superuser &prompt.user; configure &prompt.user; make &prompt.user; su - Password: &prompt.root; make install &prompt.root; exit &prompt.user; The built-in &man.su.1; framework works well for single systems or small networks with just one system administrator. An alternative is to install the security/sudo package or port. This software provides activity logging and allows the administrator to configure which users can run which commands as the superuser. Managing Accounts accounts modifying &os; provides a variety of different commands to manage user accounts. The most common commands are summarized in , followed by some examples of their usage. See the manual page for each utility for more details and usage examples. Utilities for Managing User Accounts Command Summary &man.adduser.8; The recommended command-line application for adding new users. &man.rmuser.8; The recommended command-line application for removing users. &man.chpass.1; A flexible tool for changing user database information. &man.passwd.1; The command-line tool to change user passwords. &man.pw.8; A powerful and flexible tool for modifying all aspects of user accounts.
<command>adduser</command> accounts adding adduser /usr/share/skel skeleton directory The recommended program for adding new users is &man.adduser.8;. When a new user is added, this program automatically updates /etc/passwd and /etc/group. It also creates a home directory for the new user, copies in the default configuration files from /usr/share/skel, and can optionally mail the new user a welcome message. This utility must be run as the superuser. The &man.adduser.8; utility is interactive and walks through the steps for creating a new user account. As seen in , either input the required information or press Return to accept the default value shown in square brackets. In this example, the user has been invited into the wheel group, allowing them to become the superuser with &man.su.1;. When finished, the utility will prompt to either create another user or to exit. Adding a User on &os; &prompt.root; adduser Username: jru Full name: J. Random User Uid (Leave empty for default): Login group [jru]: Login group is jru. Invite jru into other groups? []: wheel Login class [default]: Shell (sh csh tcsh zsh nologin) [sh]: zsh Home directory [/home/jru]: Home directory permissions (Leave empty for default): Use password-based authentication? [yes]: Use an empty password? (yes/no) [no]: Use a random password? (yes/no) [no]: Enter password: Enter password again: Lock out the account after creation? [no]: Username : jru Password : **** Full Name : J. Random User Uid : 1001 Class : Groups : jru wheel Home : /home/jru Shell : /usr/local/bin/zsh Locked : no OK? (yes/no): yes adduser: INFO: Successfully added (jru) to the user database. Add another user? (yes/no): no Goodbye! &prompt.root; Since the password is not echoed when typed, be careful to not mistype the password when creating the user account. <command>rmuser</command> rmuser accounts removing To completely remove a user from the system, run &man.rmuser.8; as the superuser. This command performs the following steps: Removes the user's &man.crontab.1; entry, if one exists. Removes any &man.at.1; jobs belonging to the user. Kills all processes owned by the user. Removes the user from the system's local password file. Optionally removes the user's home directory, if it is owned by the user. Removes the incoming mail files belonging to the user from /var/mail. Removes all files owned by the user from temporary file storage areas such as /tmp. Finally, removes the username from all groups to which it belongs in /etc/group. If a group becomes empty and the group name is the same as the username, the group is removed. This complements the per-user unique groups created by &man.adduser.8;. &man.rmuser.8; cannot be used to remove superuser accounts since that is almost always an indication of massive destruction. By default, an interactive mode is used, as shown in the following example. <command>rmuser</command> Interactive Account Removal &prompt.root; rmuser jru Matching password entry: jru:*:1001:1001::0:0:J. Random User:/home/jru:/usr/local/bin/zsh Is this the entry you wish to remove? y Remove user's home directory (/home/jru)? y Removing user (jru): mailspool home passwd. &prompt.root; <command>chpass</command> chpass Any user can use &man.chpass.1; to change their default shell and personal information associated with their user account. The superuser can use this utility to change additional account information for any user. When passed no options, aside from an optional username, &man.chpass.1; displays an editor containing user information. When the user exits from the editor, the user database is updated with the new information. This utility will prompt for the user's password when exiting the editor, unless the utility is run as the superuser. In , the superuser has typed chpass jru and is now viewing the fields that can be changed for this user. If jru runs this command instead, only the last six fields will be displayed and available for editing. This is shown in . Using <command>chpass</command> as Superuser #Changing user database information for jru. Login: jru Password: * Uid [#]: 1001 Gid [# or name]: 1001 Change [month day year]: Expire [month day year]: Class: Home directory: /home/jru Shell: /usr/local/bin/zsh Full Name: J. Random User Office Location: Office Phone: Home Phone: Other information: Using <command>chpass</command> as Regular User #Changing user database information for jru. Shell: /usr/local/bin/zsh Full Name: J. Random User Office Location: Office Phone: Home Phone: Other information: The commands &man.chfn.1; and &man.chsh.1; are links to &man.chpass.1;, as are &man.ypchpass.1;, &man.ypchfn.1;, and &man.ypchsh.1;. Since NIS support is automatic, specifying the yp before the command is not necessary. How to configure NIS is covered in . <command>passwd</command> passwd accounts changing password Any user can easily change their password using &man.passwd.1;. To prevent accidental or unauthorized changes, this command will prompt for the user's original password before a new password can be set: Changing Your Password &prompt.user; passwd Changing local password for jru. Old password: New password: Retype new password: passwd: updating the database... passwd: done The superuser can change any user's password by specifying the username when running &man.passwd.1;. When this utility is run as the superuser, it will not prompt for the user's current password. This allows the password to be changed when a user cannot remember the original password. Changing Another User's Password as the Superuser &prompt.root; passwd jru Changing local password for jru. New password: Retype new password: passwd: updating the database... passwd: done As with &man.chpass.1;, &man.yppasswd.1; is a link to &man.passwd.1;, so NIS works with either command. <command>pw</command> pw The &man.pw.8; utility can create, remove, modify, and display users and groups. It functions as a front end to the system user and group files. &man.pw.8; has a very powerful set of command line options that make it suitable for use in shell scripts, but new users may find it more complicated than the other commands presented in this section. Managing Groups groups /etc/groups accounts groups A group is a list of users. A group is identified by its group name and GID. In &os;, the kernel uses the UID of a process, and the list of groups it belongs to, to determine what the process is allowed to do. Most of the time, the GID of a user or process usually means the first group in the list. The group name to GID mapping is listed in /etc/group. This is a plain text file with four colon-delimited fields. The first field is the group name, the second is the encrypted password, the third the GID, and the fourth the comma-delimited list of members. For a more complete description of the syntax, refer to &man.group.5;. The superuser can modify /etc/group using a text editor. Alternatively, &man.pw.8; can be used to add and edit groups. For example, to add a group called teamtwo and then confirm that it exists: Adding a Group Using &man.pw.8; &prompt.root; pw groupadd teamtwo &prompt.root; pw groupshow teamtwo teamtwo:*:1100: In this example, 1100 is the GID of teamtwo. Right now, teamtwo has no members. This command will add jru as a member of teamtwo. Adding User Accounts to a New Group Using &man.pw.8; &prompt.root; pw groupmod teamtwo -M jru &prompt.root; pw groupshow teamtwo teamtwo:*:1100:jru The argument to is a comma-delimited list of users to be added to a new (empty) group or to replace the members of an existing group. To the user, this group membership is different from (and in addition to) the user's primary group listed in the password file. This means that the user will not show up as a member when using with &man.pw.8;, but will show up when the information is queried via &man.id.1; or a similar tool. When &man.pw.8; is used to add a user to a group, it only manipulates /etc/group and does not attempt to read additional data from /etc/passwd. Adding a New Member to a Group Using &man.pw.8; &prompt.root; pw groupmod teamtwo -m db &prompt.root; pw groupshow teamtwo teamtwo:*:1100:jru,db In this example, the argument to is a comma-delimited list of users who are to be added to the group. Unlike the previous example, these users are appended to the group and do not replace existing users in the group. Using &man.id.1; to Determine Group Membership &prompt.user; id jru uid=1001(jru) gid=1001(jru) groups=1001(jru), 1100(teamtwo) In this example, jru is a member of the groups jru and teamtwo. For more information about this command and the format of /etc/group, refer to &man.pw.8; and &man.group.5;. Permissions UNIX In &os;, every file and directory has an associated set of permissions and several utilities are available for viewing and modifying these permissions. Understanding how permissions work is necessary to make sure that users are able to access the files that they need and are unable to improperly access the files used by the operating system or owned by other users. This section discusses the traditional &unix; permissions used in &os;. For finer grained file system access control, refer to . In &unix;, basic permissions are assigned using three types of access: read, write, and execute. These access types are used to determine file access to the file's owner, group, and others (everyone else). The read, write, and execute permissions can be represented as the letters r, w, and x. They can also be represented as binary numbers as each permission is either on or off (0). When represented as a number, the order is always read as rwx, where r has an on value of 4, w has an on value of 2 and x has an on value of 1. Table 4.1 summarizes the possible numeric and alphabetic possibilities. When reading the Directory Listing column, a - is used to represent a permission that is set to off. permissions file permissions &unix; Permissions Value Permission Directory Listing 0 No read, no write, no execute --- 1 No read, no write, execute --x 2 No read, write, no execute -w- 3 No read, write, execute -wx 4 Read, no write, no execute r-- 5 Read, no write, execute r-x 6 Read, write, no execute rw- 7 Read, write, execute rwx
&man.ls.1; directories Use the argument to &man.ls.1; to view a long directory listing that includes a column of information about a file's permissions for the owner, group, and everyone else. For example, a ls -l in an arbitrary directory may show: &prompt.user; ls -l total 530 -rw-r--r-- 1 root wheel 512 Sep 5 12:31 myfile -rw-r--r-- 1 root wheel 512 Sep 5 12:31 otherfile -rw-r--r-- 1 root wheel 7680 Sep 5 12:31 email.txt The first (leftmost) character in the first column indicates whether this file is a regular file, a directory, a special character device, a socket, or any other special pseudo-file device. In this example, the - indicates a regular file. The next three characters, rw- in this example, give the permissions for the owner of the file. The next three characters, r--, give the permissions for the group that the file belongs to. The final three characters, r--, give the permissions for the rest of the world. A dash means that the permission is turned off. In this example, the permissions are set so the owner can read and write to the file, the group can read the file, and the rest of the world can only read the file. According to the table above, the permissions for this file would be 644, where each digit represents the three parts of the file's permission. How does the system control permissions on devices? &os; treats most hardware devices as a file that programs can open, read, and write data to. These special device files are stored in /dev/. Directories are also treated as files. They have read, write, and execute permissions. The executable bit for a directory has a slightly different meaning than that of files. When a directory is marked executable, it means it is possible to change into that directory using &man.cd.1;. This also means that it is possible to access the files within that directory, subject to the permissions on the files themselves. In order to perform a directory listing, the read permission must be set on the directory. In order to delete a file that one knows the name of, it is necessary to have write and execute permissions to the directory containing the file. There are more permission bits, but they are primarily used in special circumstances such as setuid binaries and sticky directories. For more information on file permissions and how to set them, refer to &man.chmod.1;. Symbolic Permissions Tom Rhodes Contributed by permissions symbolic Symbolic permissions use characters instead of octal values to assign permissions to files or directories. Symbolic permissions use the syntax of (who) (action) (permissions), where the following values are available: Option Letter Represents (who) u User (who) g Group owner (who) o Other (who) a All (world) (action) + Adding permissions (action) - Removing permissions (action) = Explicitly set permissions (permissions) r Read (permissions) w Write (permissions) x Execute (permissions) t Sticky bit (permissions) s Set UID or GID These values are used with &man.chmod.1;, but with letters instead of numbers. For example, the following command would block other users from accessing FILE: &prompt.user; chmod go= FILE A comma separated list can be provided when more than one set of changes to a file must be made. For example, the following command removes the group and world write permission on FILE, and adds the execute permissions for everyone: &prompt.user; chmod go-w,a+x FILE &os; File Flags Tom Rhodes Contributed by In addition to file permissions, &os; supports the use of file flags. These flags add an additional level of security and control over files, but not directories. With file flags, even root can be prevented from removing or altering files. File flags are modified using &man.chflags.1;. For example, to enable the system undeletable flag on the file file1, issue the following command: &prompt.root; chflags sunlink file1 To disable the system undeletable flag, put a no in front of the : &prompt.root; chflags nosunlink file1 To view the flags of a file, use with &man.ls.1;: &prompt.root; ls -lo file1 -rw-r--r-- 1 trhodes trhodes sunlnk 0 Mar 1 05:54 file1 Several file flags may only be added or removed by the root user. In other cases, the file owner may set its file flags. Refer to &man.chflags.1; and &man.chflags.2; for more information. The <literal>setuid</literal>, <literal>setgid</literal>, and <literal>sticky</literal> Permissions Tom Rhodes Contributed by Other than the permissions already discussed, there are three other specific settings that all administrators should know about. They are the setuid, setgid, and sticky permissions. These settings are important for some &unix; operations as they provide functionality not normally granted to normal users. To understand them, the difference between the real user ID and effective user ID must be noted. The real user ID is the UID who owns or starts the process. The effective UID is the user ID the process runs as. As an example, &man.passwd.1; runs with the real user ID when a user changes their password. However, in order to update the password database, the command runs as the effective ID of the root user. This allows users to change their passwords without seeing a Permission Denied error. The setuid permission may be set by prefixing a permission set with the number four (4) as shown in the following example: &prompt.root; chmod 4755 suidexample.sh The permissions on suidexample.sh now look like the following: -rwsr-xr-x 1 trhodes trhodes 63 Aug 29 06:36 suidexample.sh Note that a s is now part of the permission set designated for the file owner, replacing the executable bit. This allows utilities which need elevated permissions, such as &man.passwd.1;. The nosuid &man.mount.8; option will cause such binaries to silently fail without alerting the user. That option is not completely reliable as a nosuid wrapper may be able to circumvent it. To view this in real time, open two terminals. On one, type passwd as a normal user. While it waits for a new password, check the process table and look at the user information for &man.passwd.1;: In terminal A: Changing local password for trhodes Old Password: In terminal B: &prompt.root; ps aux | grep passwd trhodes 5232 0.0 0.2 3420 1608 0 R+ 2:10AM 0:00.00 grep passwd root 5211 0.0 0.2 3620 1724 2 I+ 2:09AM 0:00.01 passwd Although &man.passwd.1; is run as a normal user, it is using the effective UID of root. The setgid permission performs the same function as the setuid permission; except that it alters the group settings. When an application or utility executes with this setting, it will be granted the permissions based on the group that owns the file, not the user who started the process. To set the setgid permission on a file, provide &man.chmod.1; with a leading two (2): &prompt.root; chmod 2755 sgidexample.sh In the following listing, notice that the s is now in the field designated for the group permission settings: -rwxr-sr-x 1 trhodes trhodes 44 Aug 31 01:49 sgidexample.sh In these examples, even though the shell script in question is an executable file, it will not run with a different EUID or effective user ID. This is because shell scripts may not access the &man.setuid.2; system calls. The setuid and setgid permission bits may lower system security, by allowing for elevated permissions. The third special permission, the sticky bit, can strengthen the security of a system. When the sticky bit is set on a directory, it allows file deletion only by the file owner. This is useful to prevent file deletion in public directories, such as /tmp, by users who do not own the file. To utilize this permission, prefix the permission set with a one (1): &prompt.root; chmod 1777 /tmp The sticky bit permission will display as a t at the very end of the permission set: &prompt.root; ls -al / | grep tmp drwxrwxrwt 10 root wheel 512 Aug 31 01:49 tmp Directory Structure directory hierarchy The &os; directory hierarchy is fundamental to obtaining an overall understanding of the system. The most important directory is root or, /. This directory is the first one mounted at boot time and it contains the base system necessary to prepare the operating system for multi-user operation. The root directory also contains mount points for other file systems that are mounted during the transition to multi-user operation. A mount point is a directory where additional file systems can be grafted onto a parent file system (usually the root file system). This is further described in . Standard mount points include /usr/, /var/, /tmp/, /mnt/, and /cdrom/. These directories are usually referenced to entries in /etc/fstab. This file is a table of various file systems and mount points and is read by the system. Most of the file systems in /etc/fstab are mounted automatically at boot time from the script &man.rc.8; unless their entry includes . Details can be found in . A complete description of the file system hierarchy is available in &man.hier.7;. The following table provides a brief overview of the most common directories. Directory Description / Root directory of the file system. /bin/ User utilities fundamental to both single-user and multi-user environments. /boot/ Programs and configuration files used during operating system bootstrap. /boot/defaults/ Default boot configuration files. Refer to &man.loader.conf.5; for details. /dev/ Device nodes. Refer to &man.intro.4; for details. /etc/ System configuration files and scripts. /etc/defaults/ Default system configuration files. Refer to &man.rc.8; for details. /etc/mail/ Configuration files for mail transport agents such as &man.sendmail.8;. - /etc/namedb/ - &man.named.8; configuration files. - - - /etc/periodic/ Scripts that run daily, weekly, and monthly, via &man.cron.8;. Refer to &man.periodic.8; for details. /etc/ppp/ &man.ppp.8; configuration files. /mnt/ Empty directory commonly used by system administrators as a temporary mount point. /proc/ Process file system. Refer to &man.procfs.5;, &man.mount.procfs.8; for details. /rescue/ Statically linked programs for emergency recovery as described in &man.rescue.8;. /root/ Home directory for the root account. /sbin/ System programs and administration utilities fundamental to both single-user and multi-user environments. /tmp/ Temporary files which are usually not preserved across a system reboot. A memory-based file system is often mounted at /tmp. This can be automated using the tmpmfs-related variables of &man.rc.conf.5; or with an entry in /etc/fstab; refer to &man.mdmfs.8; for details. /usr/ The majority of user utilities and applications. /usr/bin/ Common utilities, programming tools, and applications. /usr/include/ Standard C include files. /usr/lib/ Archive libraries. /usr/libdata/ Miscellaneous utility data files. /usr/libexec/ System daemons and system utilities executed by other programs. /usr/local/ Local executables and libraries. Also used as the default destination for the &os; ports framework. Within /usr/local, the general layout sketched out by &man.hier.7; for /usr should be used. Exceptions are the man directory, which is directly under /usr/local rather than under /usr/local/share, and the ports documentation is in share/doc/port. /usr/obj/ Architecture-specific target tree produced by building the /usr/src tree. /usr/ports/ The &os; Ports Collection (optional). /usr/sbin/ System daemons and system utilities executed by users. /usr/share/ Architecture-independent files. /usr/src/ BSD and/or local source files. /var/ Multi-purpose log, temporary, transient, and spool files. A memory-based file system is sometimes mounted at /var. This can be automated using the varmfs-related variables in &man.rc.conf.5; or with an entry in /etc/fstab; refer to &man.mdmfs.8; for details. /var/log/ Miscellaneous system log files. /var/mail/ User mailbox files. /var/spool/ Miscellaneous printer and mail system spooling directories. /var/tmp/ Temporary files which are usually preserved across a system reboot, unless /var is a memory-based file system. /var/yp/ NIS maps. Disk Organization The smallest unit of organization that &os; uses to find files is the filename. Filenames are case-sensitive, which means that readme.txt and README.TXT are two separate files. &os; does not use the extension of a file to determine whether the file is a program, document, or some other form of data. Files are stored in directories. A directory may contain no files, or it may contain many hundreds of files. A directory can also contain other directories, allowing a hierarchy of directories within one another in order to organize data. Files and directories are referenced by giving the file or directory name, followed by a forward slash, /, followed by any other directory names that are necessary. For example, if the directory foo contains a directory bar which contains the file readme.txt, the full name, or path, to the file is foo/bar/readme.txt. Note that this is different from &windows; which uses \ to separate file and directory names. &os; does not use drive letters, or other drive names in the path. For example, one would not type c:\foo\bar\readme.txt on &os;. Directories and files are stored in a file system. Each file system contains exactly one directory at the very top level, called the root directory for that file system. This root directory can contain other directories. One file system is designated the root file system or /. Every other file system is mounted under the root file system. No matter how many disks are on the &os; system, every directory appears to be part of the same disk. Consider three file systems, called A, B, and C. Each file system has one root directory, which contains two other directories, called A1, A2 (and likewise B1, B2 and C1, C2). Call A the root file system. If &man.ls.1; is used to view the contents of this directory, it will show two subdirectories, A1 and A2. The directory tree looks like this: / | +--- A1 | `--- A2 A file system must be mounted on to a directory in another file system. When mounting file system B on to the directory A1, the root directory of B replaces A1, and the directories in B appear accordingly: / | +--- A1 | | | +--- B1 | | | `--- B2 | `--- A2 Any files that are in the B1 or B2 directories can be reached with the path /A1/B1 or /A1/B2 as necessary. Any files that were in /A1 have been temporarily hidden. They will reappear if B is unmounted from A. If B had been mounted on A2 then the diagram would look like this: / | +--- A1 | `--- A2 | +--- B1 | `--- B2 and the paths would be /A2/B1 and /A2/B2 respectively. File systems can be mounted on top of one another. Continuing the last example, the C file system could be mounted on top of the B1 directory in the B file system, leading to this arrangement: / | +--- A1 | `--- A2 | +--- B1 | | | +--- C1 | | | `--- C2 | `--- B2 Or C could be mounted directly on to the A file system, under the A1 directory: / | +--- A1 | | | +--- C1 | | | `--- C2 | `--- A2 | +--- B1 | `--- B2 It is entirely possible to have one large root file system, and not need to create any others. There are some drawbacks to this approach, and one advantage. Benefits of Multiple File Systems Different file systems can have different mount options. For example, the root file system can be mounted read-only, making it impossible for users to inadvertently delete or edit a critical file. Separating user-writable file systems, such as /home, from other file systems allows them to be mounted nosuid. This option prevents the suid/guid bits on executables stored on the file system from taking effect, possibly improving security. &os; automatically optimizes the layout of files on a file system, depending on how the file system is being used. So a file system that contains many small files that are written frequently will have a different optimization to one that contains fewer, larger files. By having one big file system this optimization breaks down. &os;'s file systems are robust if power is lost. However, a power loss at a critical point could still damage the structure of the file system. By splitting data over multiple file systems it is more likely that the system will still come up, making it easier to restore from backup as necessary. Benefit of a Single File System File systems are a fixed size. If you create a file system when you install &os; and give it a specific size, you may later discover that you need to make the partition bigger. This is not easily accomplished without backing up, recreating the file system with the new size, and then restoring the backed up data. &os; features the &man.growfs.8; command, which makes it possible to increase the size of file system on the fly, removing this limitation. File systems are contained in partitions. This does not have the same meaning as the common usage of the term partition (for example, &ms-dos; partition), because of &os;'s &unix; heritage. Each partition is identified by a letter from a through to h. Each partition can contain only one file system, which means that file systems are often described by either their typical mount point in the file system hierarchy, or the letter of the partition they are contained in. &os; also uses disk space for swap space to provide virtual memory. This allows your computer to behave as though it has much more memory than it actually does. When &os; runs out of memory, it moves some of the data that is not currently being used to the swap space, and moves it back in (moving something else out) when it needs it. Some partitions have certain conventions associated with them. Partition Convention a Normally contains the root file system. b Normally contains swap space. c Normally the same size as the enclosing slice. This allows utilities that need to work on the entire slice, such as a bad block scanner, to work on the c partition. A file system would not normally be created on this partition. d Partition d used to have a special meaning associated with it, although that is now gone and d may work as any normal partition. Disks in &os; are divided into slices, referred to in &windows; as partitions, which are numbered from 1 to 4. These are then divided into partitions, which contain file systems, and are labeled using letters. slices partitions dangerously dedicated Slice numbers follow the device name, prefixed with an s, starting at 1. So da0s1 is the first slice on the first SCSI drive. There can only be four physical slices on a disk, but there can be logical slices inside physical slices of the appropriate type. These extended slices are numbered starting at 5, so ada0s5 is the first extended slice on the first SATA disk. These devices are used by file systems that expect to occupy a slice. Slices, dangerously dedicated physical drives, and other drives contain partitions, which are represented as letters from a to h. This letter is appended to the device name, so da0a is the a partition on the first da drive, which is dangerously dedicated. ada1s3e is the fifth partition in the third slice of the second SATA disk drive. Finally, each disk on the system is identified. A disk name starts with a code that indicates the type of disk, and then a number, indicating which disk it is. Unlike slices, disk numbering starts at 0. Common codes are listed in . When referring to a partition, include the disk name, s, the slice number, and then the partition letter. Examples are shown in . shows a conceptual model of a disk layout. When installing &os;, configure the disk slices, create partitions within the slice to be used for &os;, create a file system or swap space in each partition, and decide where each file system will be mounted. Disk Device Names Drive Type Drive Device Name SATA and IDE hard drives ada or ad SCSI hard drives and USB storage devices da SATA and IDE CD-ROM drives cd or acd SCSI CD-ROM drives cd Floppy drives fd Assorted non-standard CD-ROM drives mcd for Mitsumi CD-ROM and scd for Sony CD-ROM devices SCSI tape drives sa IDE tape drives ast RAID drives Examples include aacd for &adaptec; AdvancedRAID, mlxd and mlyd for &mylex;, amrd for AMI &megaraid;, idad for Compaq Smart RAID, twed for &tm.3ware; RAID.
Sample Disk, Slice, and Partition Names Name Meaning ada0s1a The first partition (a) on the first slice (s1) on the first SATA disk (ada0). da1s2e The fifth partition (e) on the second slice (s2) on the second SCSI disk (da1). Conceptual Model of a Disk This diagram shows &os;'s view of the first SATA disk attached to the system. Assume that the disk is 250 GB in size, and contains an 80 GB slice and a 170 GB slice (&ms-dos; partitions). The first slice contains a &windows; NTFS file system, C:, and the second slice contains a &os; installation. This example &os; installation has four data partitions and a swap partition. The four partitions each hold a file system. Partition a is used for the root file system, d for /var/, e for /tmp/, and f for /usr/. Partition letter c refers to the entire slice, and so is not used for ordinary partitions. Mounting and Unmounting File Systems The file system is best visualized as a tree, rooted, as it were, at /. /dev, /usr, and the other directories in the root directory are branches, which may have their own branches, such as /usr/local, and so on. root file system There are various reasons to house some of these directories on separate file systems. /var contains the directories log/, spool/, and various types of temporary files, and as such, may get filled up. Filling up the root file system is not a good idea, so splitting /var from / is often favorable. Another common reason to contain certain directory trees on other file systems is if they are to be housed on separate physical disks, or are separate virtual disks, such as Network File System mounts, described in , or CDROM drives. The <filename>fstab</filename> File file systems mounted with fstab During the boot process (), file systems listed in /etc/fstab are automatically mounted except for the entries containing . This file contains entries in the following format: device /mount-point fstype options dumpfreq passno device An existing device name as explained in . mount-point An existing directory on which to mount the file system. fstype The file system type to pass to &man.mount.8;. The default &os; file system is ufs. options Either for read-write file systems, or for read-only file systems, followed by any other options that may be needed. A common option is for file systems not normally mounted during the boot sequence. Other options are listed in &man.mount.8;. dumpfreq Used by &man.dump.8; to determine which file systems require dumping. If the field is missing, a value of zero is assumed. passno Determines the order in which file systems should be checked. File systems that should be skipped should have their passno set to zero. The root file system needs to be checked before everything else and should have its passno set to one. The other file systems should be set to values greater than one. If more than one file system has the same passno, &man.fsck.8; will attempt to check file systems in parallel if possible. Refer to &man.fstab.5; for more information on the format of /etc/fstab and its options. Using &man.mount.8; file systems mounting File systems are mounted using &man.mount.8;. The most basic syntax is as follows: &prompt.root; mount device mountpoint This command provides many options which are described in &man.mount.8;, The most commonly used options include: Mount Options Mount all the file systems listed in /etc/fstab, except those marked as noauto, excluded by the flag, or those that are already mounted. Do everything except for the actual mount system call. This option is useful in conjunction with the flag to determine what &man.mount.8; is actually trying to do. Force the mount of an unclean file system (dangerous), or the revocation of write access when downgrading a file system's mount status from read-write to read-only. Mount the file system read-only. This is identical to using . fstype Mount the specified file system type or mount only file systems of the given type, if is included. ufs is the default file system type. Update mount options on the file system. Be verbose. Mount the file system read-write. The following options can be passed to as a comma-separated list: nosuid Do not interpret setuid or setgid flags on the file system. This is also a useful security option. Using &man.umount.8; file systems unmounting To unmount a file system use &man.umount.8;. This command takes one parameter which can be a mountpoint, device name, or . All forms take to force unmounting, and for verbosity. Be warned that is not generally a good idea as it might crash the computer or damage data on the file system. To unmount all mounted file systems, or just the file system types listed after , use or . Note that does not attempt to unmount the root file system. Processes and Daemons &os; is a multi-tasking operating system. Each program running at any one time is called a process. Every running command starts at least one new process and there are a number of system processes that are run by &os;. Each process is uniquely identified by a number called a process ID (PID). Similar to files, each process has one owner and group, and the owner and group permissions are used to determine which files and devices the process can open. Most processes also have a parent process that started them. For example, the shell is a process, and any command started in the shell is a process which has the shell as its parent process. The exception is a special process called &man.init.8; which is always the first process to start at boot time and which always has a PID of 1. Some programs are not designed to be run with continuous user input and disconnect from the terminal at the first opportunity. For example, a web server responds to web requests, rather than user input. Mail servers are another example of this type of application. These types of programs are known as daemons. The term daemon comes from Greek mythology and represents an entity that is neither good nor evil, and which invisibly performs useful tasks. This is why the BSD mascot is the cheerful-looking daemon with sneakers and a pitchfork. There is a convention to name programs that normally run as daemons with a trailing d. For example, BIND is the Berkeley Internet Name Domain, but the actual program that executes is named. The Apache web server program is httpd and the line printer spooling daemon is lpd. This is only a naming convention. For example, the main mail daemon for the Sendmail application is sendmail, and not maild. Viewing Processes To see the processes running on the system, use &man.ps.1; or &man.top.1;. To display a static list of the currently running processes, their PIDs, how much memory they are using, and the command they were started with, use &man.ps.1;. To display all the running processes and update the display every few seconds in order to interactively see what the computer is doing, use &man.top.1;. By default, &man.ps.1; only shows the commands that are running and owned by the user. For example: &prompt.user; ps PID TT STAT TIME COMMAND 8203 0 Ss 0:00.59 /bin/csh 8895 0 R+ 0:00.00 ps The output from &man.ps.1; is organized into a number of columns. The PID column displays the process ID. PIDs are assigned starting at 1, go up to 99999, then wrap around back to the beginning. However, a PID is not reassigned if it is already in use. The TT column shows the tty the program is running on and STAT shows the program's state. TIME is the amount of time the program has been running on the CPU. This is usually not the elapsed time since the program was started, as most programs spend a lot of time waiting for things to happen before they need to spend time on the CPU. Finally, COMMAND is the command that was used to start the program. A number of different options are available to change the information that is displayed. One of the most useful sets is auxww, where displays information about all the running processes of all users, displays the username and memory usage of the process' owner, displays information about daemon processes, and causes &man.ps.1; to display the full command line for each process, rather than truncating it once it gets too long to fit on the screen. The output from &man.top.1; is similar: &prompt.user; top last pid: 9609; load averages: 0.56, 0.45, 0.36 up 0+00:20:03 10:21:46 107 processes: 2 running, 104 sleeping, 1 zombie CPU: 6.2% user, 0.1% nice, 8.2% system, 0.4% interrupt, 85.1% idle Mem: 541M Active, 450M Inact, 1333M Wired, 4064K Cache, 1498M Free ARC: 992M Total, 377M MFU, 589M MRU, 250K Anon, 5280K Header, 21M Other Swap: 2048M Total, 2048M Free PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 557 root 1 -21 r31 136M 42296K select 0 2:20 9.96% Xorg 8198 dru 2 52 0 449M 82736K select 3 0:08 5.96% kdeinit4 8311 dru 27 30 0 1150M 187M uwait 1 1:37 0.98% firefox 431 root 1 20 0 14268K 1728K select 0 0:06 0.98% moused 9551 dru 1 21 0 16600K 2660K CPU3 3 0:01 0.98% top 2357 dru 4 37 0 718M 141M select 0 0:21 0.00% kdeinit4 8705 dru 4 35 0 480M 98M select 2 0:20 0.00% kdeinit4 8076 dru 6 20 0 552M 113M uwait 0 0:12 0.00% soffice.bin 2623 root 1 30 10 12088K 1636K select 3 0:09 0.00% powerd 2338 dru 1 20 0 440M 84532K select 1 0:06 0.00% kwin 1427 dru 5 22 0 605M 86412K select 1 0:05 0.00% kdeinit4 The output is split into two sections. The header (the first five or six lines) shows the PID of the last process to run, the system load averages (which are a measure of how busy the system is), the system uptime (time since the last reboot) and the current time. The other figures in the header relate to how many processes are running, how much memory and swap space has been used, and how much time the system is spending in different CPU states. If the ZFS file system module has been loaded, an ARC line indicates how much data was read from the memory cache instead of from disk. Below the header is a series of columns containing similar information to the output from &man.ps.1;, such as the PID, username, amount of CPU time, and the command that started the process. By default, &man.top.1; also displays the amount of memory space taken by the process. This is split into two columns: one for total size and one for resident size. Total size is how much memory the application has needed and the resident size is how much it is actually using now. &man.top.1; automatically updates the display every two seconds. A different interval can be specified with . Killing Processes One way to communicate with any running process or daemon is to send a signal using &man.kill.1;. There are a number of different signals; some have a specific meaning while others are described in the application's documentation. A user can only send a signal to a process they own and sending a signal to someone else's process will result in a permission denied error. The exception is the root user, who can send signals to anyone's processes. The operating system can also send a signal to a process. If an application is badly written and tries to access memory that it is not supposed to, &os; will send the process the Segmentation Violation signal (SIGSEGV). If an application has been written to use the &man.alarm.3; system call to be alerted after a period of time has elapsed, it will be sent the Alarm signal (SIGALRM). Two signals can be used to stop a process: SIGTERM and SIGKILL. SIGTERM is the polite way to kill a process as the process can read the signal, close any log files it may have open, and attempt to finish what it is doing before shutting down. In some cases, a process may ignore SIGTERM if it is in the middle of some task that cannot be interrupted. SIGKILL cannot be ignored by a process. Sending a SIGKILL to a process will usually stop that process there and then. There are a few tasks that cannot be interrupted. For example, if the process is trying to read from a file that is on another computer on the network, and the other computer is unavailable, the process is said to be uninterruptible. Eventually the process will time out, typically after two minutes. As soon as this time out occurs the process will be killed.. Other commonly used signals are SIGHUP, SIGUSR1, and SIGUSR2. Since these are general purpose signals, different applications will respond differently. For example, after changing a web server's configuration file, the web server needs to be told to re-read its configuration. Restarting httpd would result in a brief outage period on the web server. Instead, send the daemon the SIGHUP signal. Be aware that different daemons will have different behavior, so refer to the documentation for the daemon to determine if SIGHUP will achieve the desired results. Sending a Signal to a Process This example shows how to send a signal to &man.inetd.8;. The &man.inetd.8; configuration file is /etc/inetd.conf, and &man.inetd.8; will re-read this configuration file when it is sent a SIGHUP. Find the PID of the process to send the signal to using &man.pgrep.1;. In this example, the PID for &man.inetd.8; is 198: &prompt.user; pgrep -l inetd 198 inetd -wW Use &man.kill.1; to send the signal. Because &man.inetd.8; is owned by root, use &man.su.1; to become root first. &prompt.user; su Password: &prompt.root; /bin/kill -s HUP 198 Like most &unix; commands, &man.kill.1; will not print any output if it is successful. If a signal is sent to a process not owned by that user, the message kill: PID: Operation not permitted will be displayed. Mistyping the PID will either send the signal to the wrong process, which could have negative results, or will send the signal to a PID that is not currently in use, resulting in the error kill: PID: No such process. Why Use <command>/bin/kill</command>? Many shells provide kill as a built in command, meaning that the shell will send the signal directly, rather than running /bin/kill. Be aware that different shells have a different syntax for specifying the name of the signal to send. Rather than try to learn all of them, it can be simpler to specify /bin/kill. When sending other signals, substitute TERM or KILL with the name of the signal. Killing a random process on the system is a bad idea. In particular, &man.init.8;, PID 1, is special. Running /bin/kill -s KILL 1 is a quick, and unrecommended, way to shutdown the system. Always double check the arguments to &man.kill.1; before pressing Return. Shells shells command line A shell provides a command line interface for interacting with the operating system. A shell receives commands from the input channel and executes them. Many shells provide built in functions to help with everyday tasks such as file management, file globbing, command line editing, command macros, and environment variables. &os; comes with several shells, including the Bourne shell (&man.sh.1;) and the extended C shell (&man.tcsh.1;). Other shells are available from the &os; Ports Collection, such as zsh and bash. The shell that is used is really a matter of taste. A C programmer might feel more comfortable with a C-like shell such as &man.tcsh.1;. A &linux; user might prefer bash. Each shell has unique properties that may or may not work with a user's preferred working environment, which is why there is a choice of which shell to use. One common shell feature is filename completion. After a user types the first few letters of a command or filename and presses Tab, the shell completes the rest of the command or filename. Consider two files called foobar and football. To delete foobar, the user might type rm foo and press Tab to complete the filename. But the shell only shows rm foo. It was unable to complete the filename because both foobar and football start with foo. Some shells sound a beep or show all the choices if more than one name matches. The user must then type more characters to identify the desired filename. Typing a t and pressing Tab again is enough to let the shell determine which filename is desired and fill in the rest. environment variables Another feature of the shell is the use of environment variables. Environment variables are a variable/key pair stored in the shell's environment. This environment can be read by any program invoked by the shell, and thus contains a lot of program configuration. provides a list of common environment variables and their meanings. Note that the names of environment variables are always in uppercase. Common Environment Variables Variable Description USER Current logged in user's name. PATH Colon-separated list of directories to search for binaries. DISPLAY Network name of the &xorg; display to connect to, if available. SHELL The current shell. TERM The name of the user's type of terminal. Used to determine the capabilities of the terminal. TERMCAP Database entry of the terminal escape codes to perform various terminal functions. OSTYPE Type of operating system. MACHTYPE The system's CPU architecture. EDITOR The user's preferred text editor. PAGER The user's preferred utility for viewing text one page at a time. MANPATH Colon-separated list of directories to search for manual pages.
Bourne shells How to set an environment variable differs between shells. In &man.tcsh.1; and &man.csh.1;, use setenv to set environment variables. In &man.sh.1; and bash, use export to set the current environment variables. This example sets the default EDITOR to /usr/local/bin/emacs for the &man.tcsh.1; shell: &prompt.user; setenv EDITOR /usr/local/bin/emacs The equivalent command for bash would be: &prompt.user; export EDITOR="/usr/local/bin/emacs" To expand an environment variable in order to see its current setting, type a $ character in front of its name on the command line. For example, echo $TERM displays the current $TERM setting. Shells treat special characters, known as meta-characters, as special representations of data. The most common meta-character is *, which represents any number of characters in a filename. Meta-characters can be used to perform filename globbing. For example, echo * is equivalent to ls because the shell takes all the files that match * and echo lists them on the command line. To prevent the shell from interpreting a special character, escape it from the shell by starting it with a backslash (\). For example, echo $TERM prints the terminal setting whereas echo \$TERM literally prints the string $TERM. Changing the Shell The easiest way to permanently change the default shell is to use chsh. Running this command will open the editor that is configured in the EDITOR environment variable, which by default is set to &man.vi.1;. Change the Shell: line to the full path of the new shell. Alternately, use chsh -s which will set the specified shell without opening an editor. For example, to change the shell to bash: &prompt.user; chsh -s /usr/local/bin/bash The new shell must be present in /etc/shells. If the shell was installed from the &os; Ports Collection as described in , it should be automatically added to this file. If it is missing, add it using this command, replacing the path with the path of the shell: &prompt.root; echo /usr/local/bin/bash >> /etc/shells Then, rerun &man.chsh.1;. Advanced Shell Techniques Tom Rhodes Written by The &unix; shell is not just a command interpreter, it acts as a powerful tool which allows users to execute commands, redirect their output, redirect their input and chain commands together to improve the final command output. When this functionality is mixed with built in commands, the user is provided with an environment that can maximize efficiency. Shell redirection is the action of sending the output or the input of a command into another command or into a file. To capture the output of the &man.ls.1; command, for example, into a file, redirect the output: &prompt.user; ls > directory_listing.txt The directory contents will now be listed in directory_listing.txt. Some commands can be used to read input, such as &man.sort.1;. To sort this listing, redirect the input: &prompt.user; sort < directory_listing.txt The input will be sorted and placed on the screen. To redirect that input into another file, one could redirect the output of &man.sort.1; by mixing the direction: &prompt.user; sort < directory_listing.txt > sorted.txt In all of the previous examples, the commands are performing redirection using file descriptors. Every &unix; system has file descriptors, which include standard input (stdin), standard output (stdout), and standard error (stderr). Each one has a purpose, where input could be a keyboard or a mouse, something that provides input. Output could be a screen or paper in a printer. And error would be anything that is used for diagnostic or error messages. All three are considered I/O based file descriptors and sometimes considered streams. Through the use of these descriptors, the shell allows output and input to be passed around through various commands and redirected to or from a file. Another method of redirection is the pipe operator. The &unix; pipe operator, | allows the output of one command to be directly passed or directed to another program. Basically, a pipe allows the standard output of a command to be passed as standard input to another command, for example: &prompt.user; cat directory_listing.txt | sort | less In that example, the contents of directory_listing.txt will be sorted and the output passed to &man.less.1;. This allows the user to scroll through the output at their own pace and prevent it from scrolling off the screen. Text Editors text editors editors Most &os; configuration is done by editing text files. Because of this, it is a good idea to become familiar with a text editor. &os; comes with a few as part of the base system, and many more are available in the Ports Collection. ee editors &man.ee.1; A simple editor to learn is &man.ee.1;, which stands for easy editor. To start this editor, type ee filename where filename is the name of the file to be edited. Once inside the editor, all of the commands for manipulating the editor's functions are listed at the top of the display. The caret (^) represents Ctrl, so ^e expands to Ctrl e . To leave &man.ee.1;, press Esc, then choose the leave editor option from the main menu. The editor will prompt to save any changes if the file has been modified. vi editors emacs &os; also comes with more powerful text editors, such as &man.vi.1;, as part of the base system. Other editors, like editors/emacs and editors/vim, are part of the &os; Ports Collection. These editors offer more functionality at the expense of being more complicated to learn. Learning a more powerful editor such as vim or Emacs can save more time in the long run. Many applications which modify files or require typed input will automatically open a text editor. To change the default editor, set the EDITOR environment variable as described in . Devices and Device Nodes A device is a term used mostly for hardware-related activities in a system, including disks, printers, graphics cards, and keyboards. When &os; boots, the majority of the boot messages refer to devices being detected. A copy of the boot messages are saved to /var/run/dmesg.boot. Each device has a device name and number. For example, ada0 is the first SATA hard drive, while kbd0 represents the keyboard. Most devices in &os; must be accessed through special files called device nodes, which are located in /dev. Manual Pages manual pages The most comprehensive documentation on &os; is in the form of manual pages. Nearly every program on the system comes with a short reference manual explaining the basic operation and available arguments. These manuals can be viewed using man: &prompt.user; man command where command is the name of the command to learn about. For example, to learn more about &man.ls.1;, type: &prompt.user; man ls Manual pages are divided into sections which represent the type of topic. In &os;, the following sections are available: User commands. System calls and error numbers. Functions in the C libraries. Device drivers. File formats. Games and other diversions. Miscellaneous information. System maintenance and operation commands. System kernel interfaces. In some cases, the same topic may appear in more than one section of the online manual. For example, there is a chmod user command and a chmod() system call. To tell &man.man.1; which section to display, specify the section number: &prompt.user; man 1 chmod This will display the manual page for the user command &man.chmod.1;. References to a particular section of the online manual are traditionally placed in parenthesis in written documentation, so &man.chmod.1; refers to the user command and &man.chmod.2; refers to the system call. If the name of the manual page is unknown, use man -k to search for keywords in the manual page descriptions: &prompt.user; man -k mail This command displays a list of commands that have the keyword mail in their descriptions. This is equivalent to using &man.apropos.1;. To read the descriptions for all of the commands in /usr/bin, type: &prompt.user; cd /usr/bin &prompt.user; man -f * | more or &prompt.user; cd /usr/bin &prompt.user; whatis * |more GNU Info Files Free Software Foundation &os; includes several applications and utilities produced by the Free Software Foundation (FSF). In addition to manual pages, these programs may include hypertext documents called info files. These can be viewed using &man.info.1; or, if editors/emacs is installed, the info mode of emacs. To use &man.info.1;, type: &prompt.user; info For a brief introduction, type h. For a quick command reference, type ?. Index: head/en_US.ISO8859-1/books/handbook/config/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/handbook/config/chapter.xml (revision 51389) +++ head/en_US.ISO8859-1/books/handbook/config/chapter.xml (revision 51390) @@ -1,3531 +1,3524 @@ Configuration and Tuning Chern Lee Written by Mike Smith Based on a tutorial written by Matt Dillon Also based on tuning(7) written by Synopsis system configuration system optimization One of the important aspects of &os; is proper system configuration. This chapter explains much of the &os; configuration process, including some of the parameters which can be set to tune a &os; system. After reading this chapter, you will know: The basics of rc.conf configuration and /usr/local/etc/rc.d startup scripts. How to configure and test a network card. How to configure virtual hosts on network devices. How to use the various configuration files in /etc. How to tune &os; using &man.sysctl.8; variables. How to tune disk performance and modify kernel limitations. Before reading this chapter, you should: Understand &unix; and &os; basics (). Be familiar with the basics of kernel configuration and compilation (). Starting Services Tom Rhodes Contributed by services Many users install third party software on &os; from the Ports Collection and require the installed services to be started upon system initialization. Services, such as mail/postfix or www/apache22 are just two of the many software packages which may be started during system initialization. This section explains the procedures available for starting third party software. In &os;, most included services, such as &man.cron.8;, are started through the system startup scripts. Extended Application Configuration Now that &os; includes rc.d, configuration of application startup is easier and provides more features. Using the key words discussed in , applications can be set to start after certain other services and extra flags can be passed through /etc/rc.conf in place of hard coded flags in the startup script. A basic script may look similar to the following: #!/bin/sh # # PROVIDE: utility # REQUIRE: DAEMON # KEYWORD: shutdown . /etc/rc.subr name=utility rcvar=utility_enable command="/usr/local/sbin/utility" load_rc_config $name # # DO NOT CHANGE THESE DEFAULT VALUES HERE # SET THEM IN THE /etc/rc.conf FILE # utility_enable=${utility_enable-"NO"} pidfile=${utility_pidfile-"/var/run/utility.pid"} run_rc_command "$1" This script will ensure that the provided utility will be started after the DAEMON pseudo-service. It also provides a method for setting and tracking the process ID (PID). This application could then have the following line placed in /etc/rc.conf: utility_enable="YES" This method allows for easier manipulation of command line arguments, inclusion of the default functions provided in /etc/rc.subr, compatibility with &man.rcorder.8;, and provides for easier configuration via rc.conf. Using Services to Start Services Other services can be started using &man.inetd.8;. Working with &man.inetd.8; and its configuration is described in depth in . In some cases, it may make more sense to use &man.cron.8; to start system services. This approach has a number of advantages as &man.cron.8; runs these processes as the owner of the &man.crontab.5;. This allows regular users to start and maintain their own applications. The @reboot feature of &man.cron.8;, may be used in place of the time specification. This causes the job to run when &man.cron.8; is started, normally during system initialization. Configuring &man.cron.8; Tom Rhodes Contributed by cron configuration One of the most useful utilities in &os; is cron. This utility runs in the background and regularly checks /etc/crontab for tasks to execute and searches /var/cron/tabs for custom crontab files. These files are used to schedule tasks which cron runs at the specified times. Each entry in a crontab defines a task to run and is known as a cron job. Two different types of configuration files are used: the system crontab, which should not be modified, and user crontabs, which can be created and edited as needed. The format used by these files is documented in &man.crontab.5;. The format of the system crontab, /etc/crontab includes a who column which does not exist in user crontabs. In the system crontab, cron runs the command as the user specified in this column. In a user crontab, all commands run as the user who created the crontab. User crontabs allow individual users to schedule their own tasks. The root user can also have a user crontab which can be used to schedule tasks that do not exist in the system crontab. Here is a sample entry from the system crontab, /etc/crontab: # /etc/crontab - root's crontab for FreeBSD # # $FreeBSD$ # SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin # #minute hour mday month wday who command # */5 * * * * root /usr/libexec/atrun Lines that begin with the # character are comments. A comment can be placed in the file as a reminder of what and why a desired action is performed. Comments cannot be on the same line as a command or else they will be interpreted as part of the command; they must be on a new line. Blank lines are ignored. The equals (=) character is used to define any environment settings. In this example, it is used to define the SHELL and PATH. If the SHELL is omitted, cron will use the default Bourne shell. If the PATH is omitted, the full path must be given to the command or script to run. This line defines the seven fields used in a system crontab: minute, hour, mday, month, wday, who, and command. The minute field is the time in minutes when the specified command will be run, the hour is the hour when the specified command will be run, the mday is the day of the month, month is the month, and wday is the day of the week. These fields must be numeric values, representing the twenty-four hour clock, or a *, representing all values for that field. The who field only exists in the system crontab and specifies which user the command should be run as. The last field is the command to be executed. This entry defines the values for this cron job. The */5, followed by several more * characters, specifies that /usr/libexec/atrun is invoked by root every five minutes of every hour, of every day and day of the week, of every month. Commands can include any number of switches. However, commands which extend to multiple lines need to be broken with the backslash \ continuation character. Creating a User Crontab To create a user crontab, invoke crontab in editor mode: &prompt.user; crontab -e This will open the user's crontab using the default text editor. The first time a user runs this command, it will open an empty file. Once a user creates a crontab, this command will open that file for editing. It is useful to add these lines to the top of the crontab file in order to set the environment variables and to remember the meanings of the fields in the crontab: SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin # Order of crontab fields # minute hour mday month wday command Then add a line for each command or script to run, specifying the time to run the command. This example runs the specified custom Bourne shell script every day at two in the afternoon. Since the path to the script is not specified in PATH, the full path to the script is given: 0 14 * * * /usr/home/dru/bin/mycustomscript.sh Before using a custom script, make sure it is executable and test it with the limited set of environment variables set by cron. To replicate the environment that would be used to run the above cron entry, use: env -i SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin HOME=/home/dru LOGNAME=dru /usr/home/dru/bin/mycustomscript.sh The environment set by cron is discussed in &man.crontab.5;. Checking that scripts operate correctly in a cron environment is especially important if they include any commands that delete files using wildcards. When finished editing the crontab, save the file. It will automatically be installed and cron will read the crontab and run its cron jobs at their specified times. To list the cron jobs in a crontab, use this command: &prompt.user; crontab -l 0 14 * * * /usr/home/dru/bin/mycustomscript.sh To remove all of the cron jobs in a user crontab: &prompt.user; crontab -r remove crontab for dru? y Managing Services in &os; Tom Rhodes Contributed by &os; uses the &man.rc.8; system of startup scripts during system initialization and for managing services. The scripts listed in /etc/rc.d provide basic services which can be controlled with the , , and options to &man.service.8;. For instance, &man.sshd.8; can be restarted with the following command: &prompt.root; service sshd restart This procedure can be used to start services on a running system. Services will be started automatically at boot time as specified in &man.rc.conf.5;. For example, to enable &man.natd.8; at system startup, add the following line to /etc/rc.conf: natd_enable="YES" If a line is already present, change the NO to YES. The &man.rc.8; scripts will automatically load any dependent services during the next boot, as described below. Since the &man.rc.8; system is primarily intended to start and stop services at system startup and shutdown time, the , and options will only perform their action if the appropriate /etc/rc.conf variable is set. For instance, sshd restart will only work if sshd_enable is set to in /etc/rc.conf. To , or a service regardless of the settings in /etc/rc.conf, these commands should be prefixed with one. For instance, to restart &man.sshd.8; regardless of the current /etc/rc.conf setting, execute the following command: &prompt.root; service sshd onerestart To check if a service is enabled in /etc/rc.conf, run the appropriate &man.rc.8; script with . This example checks to see if &man.sshd.8; is enabled in /etc/rc.conf: &prompt.root; service sshd rcvar # sshd # sshd_enable="YES" # (default: "") The # sshd line is output from the above command, not a root console. To determine whether or not a service is running, use . For instance, to verify that &man.sshd.8; is running: &prompt.root; service sshd status sshd is running as pid 433. In some cases, it is also possible to a service. This attempts to send a signal to an individual service, forcing the service to reload its configuration files. In most cases, this means sending the service a SIGHUP signal. Support for this feature is not included for every service. The &man.rc.8; system is used for network services and it also contributes to most of the system initialization. For instance, when the /etc/rc.d/bgfsck script is executed, it prints out the following message: Starting background file system checks in 60 seconds. This script is used for background file system checks, which occur only during system initialization. Many system services depend on other services to function properly. For example, &man.yp.8; and other RPC-based services may fail to start until after the &man.rpcbind.8; service has started. To resolve this issue, information about dependencies and other meta-data is included in the comments at the top of each startup script. The &man.rcorder.8; program is used to parse these comments during system initialization to determine the order in which system services should be invoked to satisfy the dependencies. The following key word must be included in all startup scripts as it is required by &man.rc.subr.8; to enable the startup script: PROVIDE: Specifies the services this file provides. The following key words may be included at the top of each startup script. They are not strictly necessary, but are useful as hints to &man.rcorder.8;: REQUIRE: Lists services which are required for this service. The script containing this key word will run after the specified services. BEFORE: Lists services which depend on this service. The script containing this key word will run before the specified services. By carefully setting these keywords for each startup script, an administrator has a fine-grained level of control of the startup order of the scripts, without the need for runlevels used by some &unix; operating systems. Additional information can be found in &man.rc.8; and &man.rc.subr.8;. Refer to this article for instructions on how to create custom &man.rc.8; scripts. Managing System-Specific Configuration rc files rc.conf The principal location for system configuration information is /etc/rc.conf. This file contains a wide range of configuration information and it is read at system startup to configure the system. It provides the configuration information for the rc* files. The entries in /etc/rc.conf override the default settings in /etc/defaults/rc.conf. The file containing the default settings should not be edited. Instead, all system-specific changes should be made to /etc/rc.conf. A number of strategies may be applied in clustered applications to separate site-wide configuration from system-specific configuration in order to reduce administration overhead. The recommended approach is to place system-specific configuration into /etc/rc.conf.local. For example, these entries in /etc/rc.conf apply to all systems: sshd_enable="YES" keyrate="fast" defaultrouter="10.1.1.254" Whereas these entries in /etc/rc.conf.local apply to this system only: hostname="node1.example.org" ifconfig_fxp0="inet 10.1.1.1/8" Distribute /etc/rc.conf to every system using an application such as rsync or puppet, while /etc/rc.conf.local remains unique. Upgrading the system will not overwrite /etc/rc.conf, so system configuration information will not be lost. Both /etc/rc.conf and /etc/rc.conf.local are parsed by &man.sh.1;. This allows system operators to create complex configuration scenarios. Refer to &man.rc.conf.5; for further information on this topic. Setting Up Network Interface Cards Marc Fonvieille Contributed by network cards configuration Adding and configuring a network interface card (NIC) is a common task for any &os; administrator. Locating the Correct Driver network cards driver First, determine the model of the NIC and the chip it uses. &os; supports a wide variety of NICs. Check the Hardware Compatibility List for the &os; release to see if the NIC is supported. If the NIC is supported, determine the name of the &os; driver for the NIC. Refer to /usr/src/sys/conf/NOTES and /usr/src/sys/arch/conf/NOTES for the list of NIC drivers with some information about the supported chipsets. When in doubt, read the manual page of the driver as it will provide more information about the supported hardware and any known limitations of the driver. The drivers for common NICs are already present in the GENERIC kernel, meaning the NIC should be probed during boot. The system's boot messages can be viewed by typing more /var/run/dmesg.boot and using the spacebar to scroll through the text. In this example, two Ethernet NICs using the &man.dc.4; driver are present on the system: dc0: <82c169 PNIC 10/100BaseTX> port 0xa000-0xa0ff mem 0xd3800000-0xd38 000ff irq 15 at device 11.0 on pci0 miibus0: <MII bus> on dc0 bmtphy0: <BCM5201 10/100baseTX PHY> PHY 1 on miibus0 bmtphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto dc0: Ethernet address: 00:a0:cc:da:da:da dc0: [ITHREAD] dc1: <82c169 PNIC 10/100BaseTX> port 0x9800-0x98ff mem 0xd3000000-0xd30 000ff irq 11 at device 12.0 on pci0 miibus1: <MII bus> on dc1 bmtphy1: <BCM5201 10/100baseTX PHY> PHY 1 on miibus1 bmtphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto dc1: Ethernet address: 00:a0:cc:da:da:db dc1: [ITHREAD] If the driver for the NIC is not present in GENERIC, but a driver is available, the driver will need to be loaded before the NIC can be configured and used. This may be accomplished in one of two ways: The easiest way is to load a kernel module for the NIC using &man.kldload.8;. To also automatically load the driver at boot time, add the appropriate line to /boot/loader.conf. Not all NIC drivers are available as modules. Alternatively, statically compile support for the NIC into a custom kernel. Refer to /usr/src/sys/conf/NOTES, /usr/src/sys/arch/conf/NOTES and the manual page of the driver to determine which line to add to the custom kernel configuration file. For more information about recompiling the kernel, refer to . If the NIC was detected at boot, the kernel does not need to be recompiled. Using &windows; <acronym>NDIS</acronym> Drivers NDIS NDISulator &windows; drivers µsoft.windows; device drivers KLD (kernel loadable object) Unfortunately, there are still many vendors that do not provide schematics for their drivers to the open source community because they regard such information as trade secrets. Consequently, the developers of &os; and other operating systems are left with two choices: develop the drivers by a long and pain-staking process of reverse engineering or using the existing driver binaries available for µsoft.windows; platforms. &os; provides native support for the Network Driver Interface Specification (NDIS). It includes &man.ndisgen.8; which can be used to convert a &windowsxp; driver into a format that can be used on &os;. Because the &man.ndis.4; driver uses a &windowsxp; binary, it only runs on &i386; and amd64 systems. PCI, CardBus, PCMCIA, and USB devices are supported. To use &man.ndisgen.8;, three things are needed: &os; kernel sources. A &windowsxp; driver binary with a .SYS extension. A &windowsxp; driver configuration file with a .INF extension. Download the .SYS and .INF files for the specific NIC. Generally, these can be found on the driver CD or at the vendor's website. The following examples use W32DRIVER.SYS and W32DRIVER.INF. The driver bit width must match the version of &os;. For &os;/i386, use a &windows; 32-bit driver. For &os;/amd64, a &windows; 64-bit driver is needed. The next step is to compile the driver binary into a loadable kernel module. As root, use &man.ndisgen.8;: &prompt.root; ndisgen /path/to/W32DRIVER.INF /path/to/W32DRIVER.SYS This command is interactive and prompts for any extra information it requires. A new kernel module will be generated in the current directory. Use &man.kldload.8; to load the new module: &prompt.root; kldload ./W32DRIVER_SYS.ko In addition to the generated kernel module, the ndis.ko and if_ndis.ko modules must be loaded. This should happen automatically when any module that depends on &man.ndis.4; is loaded. If not, load them manually, using the following commands: &prompt.root; kldload ndis &prompt.root; kldload if_ndis The first command loads the &man.ndis.4; miniport driver wrapper and the second loads the generated NIC driver. Check &man.dmesg.8; to see if there were any load errors. If all went well, the output should be similar to the following: ndis0: <Wireless-G PCI Adapter> mem 0xf4100000-0xf4101fff irq 3 at device 8.0 on pci1 ndis0: NDIS API version: 5.0 ndis0: Ethernet address: 0a:b1:2c:d3:4e:f5 ndis0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps ndis0: 11g rates: 6Mbps 9Mbps 12Mbps 18Mbps 36Mbps 48Mbps 54Mbps From here, ndis0 can be configured like any other NIC. To configure the system to load the &man.ndis.4; modules at boot time, copy the generated module, W32DRIVER_SYS.ko, to /boot/modules. Then, add the following line to /boot/loader.conf: W32DRIVER_SYS_load="YES" Configuring the Network Card network cards configuration Once the right driver is loaded for the NIC, the card needs to be configured. It may have been configured at installation time by &man.bsdinstall.8;. To display the NIC configuration, enter the following command: &prompt.user; ifconfig dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=80008<VLAN_MTU,LINKSTATE> ether 00:a0:cc:da:da:da inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255 media: Ethernet autoselect (100baseTX <full-duplex>) status: active dc1: flags=8802<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=80008<VLAN_MTU,LINKSTATE> ether 00:a0:cc:da:da:db inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255 media: Ethernet 10baseT/UTP status: no carrier lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 options=3<RXCSUM,TXCSUM> inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4 inet6 ::1 prefixlen 128 inet 127.0.0.1 netmask 0xff000000 nd6 options=3<PERFORMNUD,ACCEPT_RTADV> In this example, the following devices were displayed: dc0: The first Ethernet interface. dc1: The second Ethernet interface. lo0: The loopback device. &os; uses the driver name followed by the order in which the card is detected at boot to name the NIC. For example, sis2 is the third NIC on the system using the &man.sis.4; driver. In this example, dc0 is up and running. The key indicators are: UP means that the card is configured and ready. The card has an Internet (inet) address, 192.168.1.3. It has a valid subnet mask (netmask), where 0xffffff00 is the same as 255.255.255.0. It has a valid broadcast address, 192.168.1.255. The MAC address of the card (ether) is 00:a0:cc:da:da:da. The physical media selection is on autoselection mode (media: Ethernet autoselect (100baseTX <full-duplex>)). In this example, dc1 is configured to run with 10baseT/UTP media. For more information on available media types for a driver, refer to its manual page. The status of the link (status) is active, indicating that the carrier signal is detected. For dc1, the status: no carrier status is normal when an Ethernet cable is not plugged into the card. If the &man.ifconfig.8; output had shown something similar to: dc0: flags=8843<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=80008<VLAN_MTU,LINKSTATE> ether 00:a0:cc:da:da:da media: Ethernet autoselect (100baseTX <full-duplex>) status: active it would indicate the card has not been configured. The card must be configured as root. The NIC configuration can be performed from the command line with &man.ifconfig.8; but will not persist after a reboot unless the configuration is also added to /etc/rc.conf. If a DHCP server is present on the LAN, just add this line: ifconfig_dc0="DHCP" Replace dc0 with the correct value for the system. The line added, then, follow the instructions given in . If the network was configured during installation, some entries for the NIC(s) may be already present. Double check /etc/rc.conf before adding any lines. In the case, there is no DHCP server, the NIC(s) have to be configured manually. Add a line for each NIC present on the system, as seen in this example: ifconfig_dc0="inet 192.168.1.3 netmask 255.255.255.0" ifconfig_dc1="inet 10.0.0.1 netmask 255.255.255.0 media 10baseT/UTP" Replace dc0 and dc1 and the IP address information with the correct values for the system. Refer to the man page for the driver, &man.ifconfig.8;, and &man.rc.conf.5; for more details about the allowed options and the syntax of /etc/rc.conf. If the network is not using DNS, edit /etc/hosts to add the names and IP addresses of the hosts on the LAN, if they are not already there. For more information, refer to &man.hosts.5; and to /usr/share/examples/etc/hosts. If there is no DHCP server and access to the Internet is needed, manually configure the default gateway and the nameserver: &prompt.root; echo 'defaultrouter="your_default_router"' >> /etc/rc.conf &prompt.root; echo 'nameserver your_DNS_server' >> /etc/resolv.conf Testing and Troubleshooting Once the necessary changes to /etc/rc.conf are saved, a reboot can be used to test the network configuration and to verify that the system restarts without any configuration errors. Alternatively, apply the settings to the networking system with this command: &prompt.root; service netif restart If a default gateway has been set in /etc/rc.conf, also issue this command: &prompt.root; service routing restart Once the networking system has been relaunched, test the NICs. Testing the Ethernet Card network cards testing To verify that an Ethernet card is configured correctly, &man.ping.8; the interface itself, and then &man.ping.8; another machine on the LAN: &prompt.user; ping -c5 192.168.1.3 PING 192.168.1.3 (192.168.1.3): 56 data bytes 64 bytes from 192.168.1.3: icmp_seq=0 ttl=64 time=0.082 ms 64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.074 ms 64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.076 ms 64 bytes from 192.168.1.3: icmp_seq=3 ttl=64 time=0.108 ms 64 bytes from 192.168.1.3: icmp_seq=4 ttl=64 time=0.076 ms --- 192.168.1.3 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 0.074/0.083/0.108/0.013 ms &prompt.user; ping -c5 192.168.1.2 PING 192.168.1.2 (192.168.1.2): 56 data bytes 64 bytes from 192.168.1.2: icmp_seq=0 ttl=64 time=0.726 ms 64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.766 ms 64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.700 ms 64 bytes from 192.168.1.2: icmp_seq=3 ttl=64 time=0.747 ms 64 bytes from 192.168.1.2: icmp_seq=4 ttl=64 time=0.704 ms --- 192.168.1.2 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 0.700/0.729/0.766/0.025 ms To test network resolution, use the host name instead of the IP address. If there is no DNS server on the network, /etc/hosts must first be configured. To this purpose, edit /etc/hosts to add the names and IP addresses of the hosts on the LAN, if they are not already there. For more information, refer to &man.hosts.5; and to /usr/share/examples/etc/hosts. Troubleshooting network cards troubleshooting When troubleshooting hardware and software configurations, check the simple things first. Is the network cable plugged in? Are the network services properly configured? Is the firewall configured correctly? Is the NIC supported by &os;? Before sending a bug report, always check the Hardware Notes, update the version of &os; to the latest STABLE version, check the mailing list archives, and search the Internet. If the card works, yet performance is poor, read through &man.tuning.7;. Also, check the network configuration as incorrect network settings can cause slow connections. Some users experience one or two device timeout messages, which is normal for some cards. If they continue, or are bothersome, determine if the device is conflicting with another device. Double check the cable connections. Consider trying another card. To resolve watchdog timeout errors, first check the network cable. Many cards require a PCI slot which supports bus mastering. On some old motherboards, only one PCI slot allows it, usually slot 0. Check the NIC and the motherboard documentation to determine if that may be the problem. No route to host messages occur if the system is unable to route a packet to the destination host. This can happen if no default route is specified or if a cable is unplugged. Check the output of netstat -rn and make sure there is a valid route to the host. If there is not, read . ping: sendto: Permission denied error messages are often caused by a misconfigured firewall. If a firewall is enabled on &os; but no rules have been defined, the default policy is to deny all traffic, even &man.ping.8;. Refer to for more information. Sometimes performance of the card is poor or below average. In these cases, try setting the media selection mode from autoselect to the correct media selection. While this works for most hardware, it may or may not resolve the issue. Again, check all the network settings, and refer to &man.tuning.7;. Virtual Hosts virtual hosts IP aliases A common use of &os; is virtual site hosting, where one server appears to the network as many servers. This is achieved by assigning multiple network addresses to a single interface. A given network interface has one real address, and may have any number of alias addresses. These aliases are normally added by placing alias entries in /etc/rc.conf, as seen in this example: ifconfig_fxp0_alias0="inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx" Alias entries must start with alias0 using a sequential number such as alias0, alias1, and so on. The configuration process will stop at the first missing number. The calculation of alias netmasks is important. For a given interface, there must be one address which correctly represents the network's netmask. Any other addresses which fall within this network must have a netmask of all 1s, expressed as either 255.255.255.255 or 0xffffffff. For example, consider the case where the fxp0 interface is connected to two networks: 10.1.1.0 with a netmask of 255.255.255.0 and 202.0.75.16 with a netmask of 255.255.255.240. The system is to be configured to appear in the ranges 10.1.1.1 through 10.1.1.5 and 202.0.75.17 through 202.0.75.20. Only the first address in a given network range should have a real netmask. All the rest (10.1.1.2 through 10.1.1.5 and 202.0.75.18 through 202.0.75.20) must be configured with a netmask of 255.255.255.255. The following /etc/rc.conf entries configure the adapter correctly for this scenario: ifconfig_fxp0="inet 10.1.1.1 netmask 255.255.255.0" ifconfig_fxp0_alias0="inet 10.1.1.2 netmask 255.255.255.255" ifconfig_fxp0_alias1="inet 10.1.1.3 netmask 255.255.255.255" ifconfig_fxp0_alias2="inet 10.1.1.4 netmask 255.255.255.255" ifconfig_fxp0_alias3="inet 10.1.1.5 netmask 255.255.255.255" ifconfig_fxp0_alias4="inet 202.0.75.17 netmask 255.255.255.240" ifconfig_fxp0_alias5="inet 202.0.75.18 netmask 255.255.255.255" ifconfig_fxp0_alias6="inet 202.0.75.19 netmask 255.255.255.255" ifconfig_fxp0_alias7="inet 202.0.75.20 netmask 255.255.255.255" A simpler way to express this is with a space-separated list of IP address ranges. The first address will be given the indicated subnet mask and the additional addresses will have a subnet mask of 255.255.255.255. ifconfig_fxp0_aliases="inet 10.1.1.1-5/24 inet 202.0.75.17-20/28" Configuring System Logging Niclas Zeising Contributed by system logging syslog &man.syslogd.8; Generating and reading system logs is an important aspect of system administration. The information in system logs can be used to detect hardware and software issues as well as application and system configuration errors. This information also plays an important role in security auditing and incident response. Most system daemons and applications will generate log entries. &os; provides a system logger, syslogd, to manage logging. By default, syslogd is started when the system boots. This is controlled by the variable syslogd_enable in /etc/rc.conf. There are numerous application arguments that can be set using syslogd_flags in /etc/rc.conf. Refer to &man.syslogd.8; for more information on the available arguments. This section describes how to configure the &os; system logger for both local and remote logging and how to perform log rotation and log management. Configuring Local Logging syslog.conf The configuration file, /etc/syslog.conf, controls what syslogd does with log entries as they are received. There are several parameters to control the handling of incoming events. The facility describes which subsystem generated the message, such as the kernel or a daemon, and the level describes the severity of the event that occurred. This makes it possible to configure if and where a log message is logged, depending on the facility and level. It is also possible to take action depending on the application that sent the message, and in the case of remote logging, the hostname of the machine generating the logging event. This configuration file contains one line per action, where the syntax for each line is a selector field followed by an action field. The syntax of the selector field is facility.level which will match log messages from facility at level level or higher. It is also possible to add an optional comparison flag before the level to specify more precisely what is logged. Multiple selector fields can be used for the same action, and are separated with a semicolon (;). Using * will match everything. The action field denotes where to send the log message, such as to a file or remote log host. As an example, here is the default syslog.conf from &os;: # $&os;$ # # Spaces ARE valid field separators in this file. However, # other *nix-like systems still insist on using tabs as field # separators. If you are sharing this file between systems, you # may want to use only tabs as field separators here. # Consult the syslog.conf(5) manpage. *.err;kern.warning;auth.notice;mail.crit /dev/console *.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err /var/log/messages security.* /var/log/security auth.info;authpriv.info /var/log/auth.log mail.info /var/log/maillog lpr.info /var/log/lpd-errs ftp.info /var/log/xferlog cron.* /var/log/cron !-devd *.=debug /var/log/debug.log *.emerg * # uncomment this to log all writes to /dev/console to /var/log/console.log #console.info /var/log/console.log # uncomment this to enable logging of all log messages to /var/log/all.log # touch /var/log/all.log and chmod it to mode 600 before it will work #*.* /var/log/all.log # uncomment this to enable logging to a remote loghost named loghost #*.* @loghost # uncomment these if you're running inn # news.crit /var/log/news/news.crit # news.err /var/log/news/news.err # news.notice /var/log/news/news.notice # Uncomment this if you wish to see messages produced by devd # !devd # *.>=info !ppp *.* /var/log/ppp.log !* In this example: Line 8 matches all messages with a level of err or higher, as well as kern.warning, auth.notice and mail.crit, and sends these log messages to the console (/dev/console). Line 12 matches all messages from the mail facility at level info or above and logs the messages to /var/log/maillog. Line 17 uses a comparison flag (=) to only match messages at level debug and logs them to /var/log/debug.log. Line 33 is an example usage of a program specification. This makes the rules following it only valid for the specified program. In this case, only the messages generated by ppp are logged to /var/log/ppp.log. The available levels, in order from most to least critical are emerg, alert, crit, err, warning, notice, info, and debug. The facilities, in no particular order, are auth, authpriv, console, cron, daemon, ftp, kern, lpr, mail, mark, news, security, syslog, user, uucp, and local0 through local7. Be aware that other operating systems might have different facilities. To log everything of level notice and higher to /var/log/daemon.log, add the following entry: daemon.notice /var/log/daemon.log For more information about the different levels and facilities, refer to &man.syslog.3; and &man.syslogd.8;. For more information about /etc/syslog.conf, its syntax, and more advanced usage examples, see &man.syslog.conf.5;. Log Management and Rotation newsyslog newsyslog.conf log rotation log management Log files can grow quickly, taking up disk space and making it more difficult to locate useful information. Log management attempts to mitigate this. In &os;, newsyslog is used to manage log files. This built-in program periodically rotates and compresses log files, and optionally creates missing log files and signals programs when log files are moved. The log files may be generated by syslogd or by any other program which generates log files. While newsyslog is normally run from &man.cron.8;, it is not a system daemon. In the default configuration, it runs every hour. To know which actions to take, newsyslog reads its configuration file, /etc/newsyslog.conf. This file contains one line for each log file that newsyslog manages. Each line states the file owner, permissions, when to rotate that file, optional flags that affect log rotation, such as compression, and programs to signal when the log is rotated. Here is the default configuration in &os;: # configuration file for newsyslog # $FreeBSD$ # # Entries which do not specify the '/pid_file' field will cause the # syslogd process to be signalled when that log file is rotated. This # action is only appropriate for log files which are written to by the # syslogd process (ie, files listed in /etc/syslog.conf). If there # is no process which needs to be signalled when a given log file is # rotated, then the entry for that file should include the 'N' flag. # # The 'flags' field is one or more of the letters: BCDGJNUXZ or a '-'. # # Note: some sites will want to select more restrictive protections than the # defaults. In particular, it may be desirable to switch many of the 644 # entries to 640 or 600. For example, some sites will consider the # contents of maillog, messages, and lpd-errs to be confidential. In the # future, these defaults may change to more conservative ones. # # logfilename [owner:group] mode count size when flags [/pid_file] [sig_num] /var/log/all.log 600 7 * @T00 J /var/log/amd.log 644 7 100 * J /var/log/auth.log 600 7 100 @0101T JC /var/log/console.log 600 5 100 * J /var/log/cron 600 3 100 * JC /var/log/daily.log 640 7 * @T00 JN /var/log/debug.log 600 7 100 * JC /var/log/kerberos.log 600 7 100 * J /var/log/lpd-errs 644 7 100 * JC /var/log/maillog 640 7 * @T00 JC /var/log/messages 644 5 100 @0101T JC /var/log/monthly.log 640 12 * $M1D0 JN /var/log/pflog 600 3 100 * JB /var/run/pflogd.pid /var/log/ppp.log root:network 640 3 100 * JC /var/log/devd.log 644 3 100 * JC /var/log/security 600 10 100 * JC /var/log/sendmail.st 640 10 * 168 B /var/log/utx.log 644 3 * @01T05 B /var/log/weekly.log 640 5 1 $W6D0 JN /var/log/xferlog 600 7 100 * JC Each line starts with the name of the log to be rotated, optionally followed by an owner and group for both rotated and newly created files. The mode field sets the permissions on the log file and count denotes how many rotated log files should be kept. The size and when fields tell newsyslog when to rotate the file. A log file is rotated when either its size is larger than the size field or when the time in the when field has passed. An asterisk (*) means that this field is ignored. The flags field gives further instructions, such as how to compress the rotated file or to create the log file if it is missing. The last two fields are optional and specify the name of the Process ID (PID) file of a process and a signal number to send to that process when the file is rotated. For more information on all fields, valid flags, and how to specify the rotation time, refer to &man.newsyslog.conf.5;. Since newsyslog is run from &man.cron.8;, it cannot rotate files more often than it is scheduled to run from &man.cron.8;. Configuring Remote Logging Tom Rhodes Contributed by Monitoring the log files of multiple hosts can become unwieldy as the number of systems increases. Configuring centralized logging can reduce some of the administrative burden of log file administration. In &os;, centralized log file aggregation, merging, and rotation can be configured using syslogd and newsyslog. This section demonstrates an example configuration, where host A, named logserv.example.com, will collect logging information for the local network. Host B, named logclient.example.com, will be configured to pass logging information to the logging server. Log Server Configuration A log server is a system that has been configured to accept logging information from other hosts. Before configuring a log server, check the following: If there is a firewall between the logging server and any logging clients, ensure that the firewall ruleset allows UDP port 514 for both the clients and the server. The logging server and all client machines must have forward and reverse entries in the local DNS. If the network does not have a DNS server, create entries in each system's /etc/hosts. Proper name resolution is required so that log entries are not rejected by the logging server. On the log server, edit /etc/syslog.conf to specify the name of the client to receive log entries from, the logging facility to be used, and the name of the log to store the host's log entries. This example adds the hostname of B, logs all facilities, and stores the log entries in /var/log/logclient.log. Sample Log Server Configuration +logclient.example.com *.* /var/log/logclient.log When adding multiple log clients, add a similar two-line entry for each client. More information about the available facilities may be found in &man.syslog.conf.5;. Next, configure /etc/rc.conf: syslogd_enable="YES" syslogd_flags="-a logclient.example.com -v -v" The first entry starts syslogd at system boot. The second entry allows log entries from the specified client. The increases the verbosity of logged messages. This is useful for tweaking facilities as administrators are able to see what type of messages are being logged under each facility. Multiple options may be specified to allow logging from multiple clients. IP addresses and whole netblocks may also be specified. Refer to &man.syslogd.8; for a full list of possible options. Finally, create the log file: &prompt.root; touch /var/log/logclient.log At this point, syslogd should be restarted and verified: &prompt.root; service syslogd restart &prompt.root; pgrep syslog If a PID is returned, the server restarted successfully, and client configuration can begin. If the server did not restart, consult /var/log/messages for the error. Log Client Configuration A logging client sends log entries to a logging server on the network. The client also keeps a local copy of its own logs. Once a logging server has been configured, edit /etc/rc.conf on the logging client: syslogd_enable="YES" syslogd_flags="-s -v -v" The first entry enables syslogd on boot up. The second entry prevents logs from being accepted by this client from other hosts () and increases the verbosity of logged messages. Next, define the logging server in the client's /etc/syslog.conf. In this example, all logged facilities are sent to a remote system, denoted by the @ symbol, with the specified hostname: *.* @logserv.example.com After saving the edit, restart syslogd for the changes to take effect: &prompt.root; service syslogd restart To test that log messages are being sent across the network, use &man.logger.1; on the client to send a message to syslogd: &prompt.root; logger "Test message from logclient" This message should now exist both in /var/log/messages on the client and /var/log/logclient.log on the log server. Debugging Log Servers If no messages are being received on the log server, the cause is most likely a network connectivity issue, a hostname resolution issue, or a typo in a configuration file. To isolate the cause, ensure that both the logging server and the logging client are able to ping each other using the hostname specified in their /etc/rc.conf. If this fails, check the network cabling, the firewall ruleset, and the hostname entries in the DNS server or /etc/hosts on both the logging server and clients. Repeat until the ping is successful from both hosts. If the ping succeeds on both hosts but log messages are still not being received, temporarily increase logging verbosity to narrow down the configuration issue. In the following example, /var/log/logclient.log on the logging server is empty and /var/log/messages on the logging client does not indicate a reason for the failure. To increase debugging output, edit the syslogd_flags entry on the logging server and issue a restart: syslogd_flags="-d -a logclient.example.com -v -v" &prompt.root; service syslogd restart Debugging data similar to the following will flash on the console immediately after the restart: logmsg: pri 56, flags 4, from logserv.example.com, msg syslogd: restart syslogd: restarted logmsg: pri 6, flags 4, from logserv.example.com, msg syslogd: kernel boot file is /boot/kernel/kernel Logging to FILE /var/log/messages syslogd: kernel boot file is /boot/kernel/kernel cvthname(192.168.1.10) validate: dgram from IP 192.168.1.10, port 514, name logclient.example.com; rejected in rule 0 due to name mismatch. In this example, the log messages are being rejected due to a typo which results in a hostname mismatch. The client's hostname should be logclient, not logclien. Fix the typo, issue a restart, and verify the results: &prompt.root; service syslogd restart logmsg: pri 56, flags 4, from logserv.example.com, msg syslogd: restart syslogd: restarted logmsg: pri 6, flags 4, from logserv.example.com, msg syslogd: kernel boot file is /boot/kernel/kernel syslogd: kernel boot file is /boot/kernel/kernel logmsg: pri 166, flags 17, from logserv.example.com, msg Dec 10 20:55:02 <syslog.err> logserv.example.com syslogd: exiting on signal 2 cvthname(192.168.1.10) validate: dgram from IP 192.168.1.10, port 514, name logclient.example.com; accepted in rule 0. logmsg: pri 15, flags 0, from logclient.example.com, msg Dec 11 02:01:28 trhodes: Test message 2 Logging to FILE /var/log/logclient.log Logging to FILE /var/log/messages At this point, the messages are being properly received and placed in the correct file. Security Considerations As with any network service, security requirements should be considered before implementing a logging server. Log files may contain sensitive data about services enabled on the local host, user accounts, and configuration data. Network data sent from the client to the server will not be encrypted or password protected. If a need for encryption exists, consider using security/stunnel, which will transmit the logging data over an encrypted tunnel. Local security is also an issue. Log files are not encrypted during use or after log rotation. Local users may access log files to gain additional insight into system configuration. Setting proper permissions on log files is critical. The built-in log rotator, newsyslog, supports setting permissions on newly created and rotated log files. Setting log files to mode 600 should prevent unwanted access by local users. Refer to &man.newsyslog.conf.5; for additional information. Configuration Files <filename>/etc</filename> Layout There are a number of directories in which configuration information is kept. These include: /etc Generic system-specific configuration information. /etc/defaults Default versions of system configuration files. /etc/mail Extra &man.sendmail.8; configuration and other MTA configuration files. /etc/ppp Configuration for both user- and kernel-ppp programs. - /etc/namedb - Default location for &man.named.8; data. - Normally named.conf and zone - files are stored here. - - - /usr/local/etc Configuration files for installed applications. May contain per-application subdirectories. /usr/local/etc/rc.d &man.rc.8; scripts for installed applications. /var/db Automatically generated system-specific database files, such as the package database and the &man.locate.1; database. Hostnames hostname DNS <filename>/etc/resolv.conf</filename> resolv.conf How a &os; system accesses the Internet Domain Name System (DNS) is controlled by &man.resolv.conf.5;. The most common entries to /etc/resolv.conf are: nameserver The IP address of a name server the resolver should query. The servers are queried in the order listed with a maximum of three. search Search list for hostname lookup. This is normally determined by the domain of the local hostname. domain The local domain name. A typical /etc/resolv.conf looks like this: search example.com nameserver 147.11.1.11 nameserver 147.11.100.30 Only one of the search and domain options should be used. When using DHCP, &man.dhclient.8; usually rewrites /etc/resolv.conf with information received from the DHCP server. <filename>/etc/hosts</filename> hosts /etc/hosts is a simple text database which works in conjunction with DNS and NIS to provide host name to IP address mappings. Entries for local computers connected via a LAN can be added to this file for simplistic naming purposes instead of setting up a &man.named.8; server. Additionally, /etc/hosts can be used to provide a local record of Internet names, reducing the need to query external DNS servers for commonly accessed names. # $&os;$ # # # Host Database # # This file should contain the addresses and aliases for local hosts that # share this file. Replace 'my.domain' below with the domainname of your # machine. # # In the presence of the domain name service or NIS, this file may # not be consulted at all; see /etc/nsswitch.conf for the resolution order. # # ::1 localhost localhost.my.domain 127.0.0.1 localhost localhost.my.domain # # Imaginary network. #10.0.0.2 myname.my.domain myname #10.0.0.3 myfriend.my.domain myfriend # # According to RFC 1918, you can use the following IP networks for # private nets which will never be connected to the Internet: # # 10.0.0.0 - 10.255.255.255 # 172.16.0.0 - 172.31.255.255 # 192.168.0.0 - 192.168.255.255 # # In case you want to be able to connect to the Internet, you need # real official assigned numbers. Do not try to invent your own network # numbers but instead get one from your network provider (if any) or # from your regional registry (ARIN, APNIC, LACNIC, RIPE NCC, or AfriNIC.) # The format of /etc/hosts is as follows: [Internet address] [official hostname] [alias1] [alias2] ... For example: 10.0.0.1 myRealHostname.example.com myRealHostname foobar1 foobar2 Consult &man.hosts.5; for more information. Tuning with &man.sysctl.8; sysctl tuning with sysctl &man.sysctl.8; is used to make changes to a running &os; system. This includes many advanced options of the TCP/IP stack and virtual memory system that can dramatically improve performance for an experienced system administrator. Over five hundred system variables can be read and set using &man.sysctl.8;. At its core, &man.sysctl.8; serves two functions: to read and to modify system settings. To view all readable variables: &prompt.user; sysctl -a To read a particular variable, specify its name: &prompt.user; sysctl kern.maxproc kern.maxproc: 1044 To set a particular variable, use the variable=value syntax: &prompt.root; sysctl kern.maxfiles=5000 kern.maxfiles: 2088 -> 5000 Settings of sysctl variables are usually either strings, numbers, or booleans, where a boolean is 1 for yes or 0 for no. To automatically set some variables each time the machine boots, add them to /etc/sysctl.conf. For more information, refer to &man.sysctl.conf.5; and . <filename>sysctl.conf</filename> sysctl.conf sysctl The configuration file for &man.sysctl.8;, /etc/sysctl.conf, looks much like /etc/rc.conf. Values are set in a variable=value form. The specified values are set after the system goes into multi-user mode. Not all variables are settable in this mode. For example, to turn off logging of fatal signal exits and prevent users from seeing processes started by other users, the following tunables can be set in /etc/sysctl.conf: # Do not log fatal signal exits (e.g., sig 11) kern.logsigexit=0 # Prevent users from seeing information about processes that # are being run under another UID. security.bsd.see_other_uids=0 &man.sysctl.8; Read-only Tom Rhodes Contributed by In some cases it may be desirable to modify read-only &man.sysctl.8; values, which will require a reboot of the system. For instance, on some laptop models the &man.cardbus.4; device will not probe memory ranges and will fail with errors similar to: cbb0: Could not map register memory device_probe_and_attach: cbb0 attach returned 12 The fix requires the modification of a read-only &man.sysctl.8; setting. Add to /boot/loader.conf and reboot. Now &man.cardbus.4; should work properly. Tuning Disks The following section will discuss various tuning mechanisms and options which may be applied to disk devices. In many cases, disks with mechanical parts, such as SCSI drives, will be the bottleneck driving down the overall system performance. While a solution is to install a drive without mechanical parts, such as a solid state drive, mechanical drives are not going away anytime in the near future. When tuning disks, it is advisable to utilize the features of the &man.iostat.8; command to test various changes to the system. This command will allow the user to obtain valuable information on system IO. Sysctl Variables <varname>vfs.vmiodirenable</varname> vfs.vmiodirenable The vfs.vmiodirenable &man.sysctl.8; variable may be set to either 0 (off) or 1 (on). It is set to 1 by default. This variable controls how directories are cached by the system. Most directories are small, using just a single fragment (typically 1 K) in the file system and typically 512 bytes in the buffer cache. With this variable turned off, the buffer cache will only cache a fixed number of directories, even if the system has a huge amount of memory. When turned on, this &man.sysctl.8; allows the buffer cache to use the VM page cache to cache the directories, making all the memory available for caching directories. However, the minimum in-core memory used to cache a directory is the physical page size (typically 4 K) rather than 512  bytes. Keeping this option enabled is recommended if the system is running any services which manipulate large numbers of files. Such services can include web caches, large mail systems, and news systems. Keeping this option on will generally not reduce performance, even with the wasted memory, but one should experiment to find out. <varname>vfs.write_behind</varname> vfs.write_behind The vfs.write_behind &man.sysctl.8; variable defaults to 1 (on). This tells the file system to issue media writes as full clusters are collected, which typically occurs when writing large sequential files. This avoids saturating the buffer cache with dirty buffers when it would not benefit I/O performance. However, this may stall processes and under certain circumstances should be turned off. <varname>vfs.hirunningspace</varname> vfs.hirunningspace The vfs.hirunningspace &man.sysctl.8; variable determines how much outstanding write I/O may be queued to disk controllers system-wide at any given instance. The default is usually sufficient, but on machines with many disks, try bumping it up to four or five megabytes. Setting too high a value which exceeds the buffer cache's write threshold can lead to bad clustering performance. Do not set this value arbitrarily high as higher write values may add latency to reads occurring at the same time. There are various other buffer cache and VM page cache related &man.sysctl.8; values. Modifying these values is not recommended as the VM system does a good job of automatically tuning itself. <varname>vm.swap_idle_enabled</varname> vm.swap_idle_enabled The vm.swap_idle_enabled &man.sysctl.8; variable is useful in large multi-user systems with many active login users and lots of idle processes. Such systems tend to generate continuous pressure on free memory reserves. Turning this feature on and tweaking the swapout hysteresis (in idle seconds) via vm.swap_idle_threshold1 and vm.swap_idle_threshold2 depresses the priority of memory pages associated with idle processes more quickly then the normal pageout algorithm. This gives a helping hand to the pageout daemon. Only turn this option on if needed, because the tradeoff is essentially pre-page memory sooner rather than later which eats more swap and disk bandwidth. In a small system this option will have a determinable effect, but in a large system that is already doing moderate paging, this option allows the VM system to stage whole processes into and out of memory easily. <varname>hw.ata.wc</varname> hw.ata.wc Turning off IDE write caching reduces write bandwidth to IDE disks, but may sometimes be necessary due to data consistency issues introduced by hard drive vendors. The problem is that some IDE drives lie about when a write completes. With IDE write caching turned on, IDE hard drives write data to disk out of order and will sometimes delay writing some blocks indefinitely when under heavy disk load. A crash or power failure may cause serious file system corruption. Check the default on the system by observing the hw.ata.wc &man.sysctl.8; variable. If IDE write caching is turned off, one can set this read-only variable to 1 in /boot/loader.conf in order to enable it at boot time. For more information, refer to &man.ata.4;. <literal>SCSI_DELAY</literal> (<varname>kern.cam.scsi_delay</varname>) kern.cam.scsi_delay kernel options SCSI DELAY The SCSI_DELAY kernel configuration option may be used to reduce system boot times. The defaults are fairly high and can be responsible for 15 seconds of delay in the boot process. Reducing it to 5 seconds usually works with modern drives. The kern.cam.scsi_delay boot time tunable should be used. The tunable and kernel configuration option accept values in terms of milliseconds and not seconds. Soft Updates Soft Updates &man.tunefs.8; To fine-tune a file system, use &man.tunefs.8;. This program has many different options. To toggle Soft Updates on and off, use: &prompt.root; tunefs -n enable /filesystem &prompt.root; tunefs -n disable /filesystem A file system cannot be modified with &man.tunefs.8; while it is mounted. A good time to enable Soft Updates is before any partitions have been mounted, in single-user mode. Soft Updates is recommended for UFS file systems as it drastically improves meta-data performance, mainly file creation and deletion, through the use of a memory cache. There are two downsides to Soft Updates to be aware of. First, Soft Updates guarantee file system consistency in the case of a crash, but could easily be several seconds or even a minute behind updating the physical disk. If the system crashes, unwritten data may be lost. Secondly, Soft Updates delay the freeing of file system blocks. If the root file system is almost full, performing a major update, such as make installworld, can cause the file system to run out of space and the update to fail. More Details About Soft Updates Soft Updates details Meta-data updates are updates to non-content data like inodes or directories. There are two traditional approaches to writing a file system's meta-data back to disk. Historically, the default behavior was to write out meta-data updates synchronously. If a directory changed, the system waited until the change was actually written to disk. The file data buffers (file contents) were passed through the buffer cache and backed up to disk later on asynchronously. The advantage of this implementation is that it operates safely. If there is a failure during an update, meta-data is always in a consistent state. A file is either created completely or not at all. If the data blocks of a file did not find their way out of the buffer cache onto the disk by the time of the crash, &man.fsck.8; recognizes this and repairs the file system by setting the file length to 0. Additionally, the implementation is clear and simple. The disadvantage is that meta-data changes are slow. For example, rm -r touches all the files in a directory sequentially, but each directory change will be written synchronously to the disk. This includes updates to the directory itself, to the inode table, and possibly to indirect blocks allocated by the file. Similar considerations apply for unrolling large hierarchies using tar -x. The second approach is to use asynchronous meta-data updates. This is the default for a UFS file system mounted with mount -o async. Since all meta-data updates are also passed through the buffer cache, they will be intermixed with the updates of the file content data. The advantage of this implementation is there is no need to wait until each meta-data update has been written to disk, so all operations which cause huge amounts of meta-data updates work much faster than in the synchronous case. This implementation is still clear and simple, so there is a low risk for bugs creeping into the code. The disadvantage is that there is no guarantee for a consistent state of the file system. If there is a failure during an operation that updated large amounts of meta-data, like a power failure or someone pressing the reset button, the file system will be left in an unpredictable state. There is no opportunity to examine the state of the file system when the system comes up again as the data blocks of a file could already have been written to the disk while the updates of the inode table or the associated directory were not. It is impossible to implement a &man.fsck.8; which is able to clean up the resulting chaos because the necessary information is not available on the disk. If the file system has been damaged beyond repair, the only choice is to reformat it and restore from backup. The usual solution for this problem is to implement dirty region logging, which is also referred to as journaling. Meta-data updates are still written synchronously, but only into a small region of the disk. Later on, they are moved to their proper location. Because the logging area is a small, contiguous region on the disk, there are no long distances for the disk heads to move, even during heavy operations, so these operations are quicker than synchronous updates. Additionally, the complexity of the implementation is limited, so the risk of bugs being present is low. A disadvantage is that all meta-data is written twice, once into the logging region and once to the proper location, so performance pessimization might result. On the other hand, in case of a crash, all pending meta-data operations can be either quickly rolled back or completed from the logging area after the system comes up again, resulting in a fast file system startup. Kirk McKusick, the developer of Berkeley FFS, solved this problem with Soft Updates. All pending meta-data updates are kept in memory and written out to disk in a sorted sequence (ordered meta-data updates). This has the effect that, in case of heavy meta-data operations, later updates to an item catch the earlier ones which are still in memory and have not already been written to disk. All operations are generally performed in memory before the update is written to disk and the data blocks are sorted according to their position so that they will not be on the disk ahead of their meta-data. If the system crashes, an implicit log rewind causes all operations which were not written to the disk appear as if they never happened. A consistent file system state is maintained that appears to be the one of 30 to 60 seconds earlier. The algorithm used guarantees that all resources in use are marked as such in their blocks and inodes. After a crash, the only resource allocation error that occurs is that resources are marked as used which are actually free. &man.fsck.8; recognizes this situation, and frees the resources that are no longer used. It is safe to ignore the dirty state of the file system after a crash by forcibly mounting it with mount -f. In order to free resources that may be unused, &man.fsck.8; needs to be run at a later time. This is the idea behind the background &man.fsck.8;: at system startup time, only a snapshot of the file system is recorded and &man.fsck.8; is run afterwards. All file systems can then be mounted dirty, so the system startup proceeds in multi-user mode. Then, background &man.fsck.8; is scheduled for all file systems where this is required, to free resources that may be unused. File systems that do not use Soft Updates still need the usual foreground &man.fsck.8;. The advantage is that meta-data operations are nearly as fast as asynchronous updates and are faster than logging, which has to write the meta-data twice. The disadvantages are the complexity of the code, a higher memory consumption, and some idiosyncrasies. After a crash, the state of the file system appears to be somewhat older. In situations where the standard synchronous approach would have caused some zero-length files to remain after the &man.fsck.8;, these files do not exist at all with Soft Updates because neither the meta-data nor the file contents have been written to disk. Disk space is not released until the updates have been written to disk, which may take place some time after running &man.rm.1;. This may cause problems when installing large amounts of data on a file system that does not have enough free space to hold all the files twice. Tuning Kernel Limits tuning kernel limits File/Process Limits <varname>kern.maxfiles</varname> kern.maxfiles The kern.maxfiles &man.sysctl.8; variable can be raised or lowered based upon system requirements. This variable indicates the maximum number of file descriptors on the system. When the file descriptor table is full, file: table is full will show up repeatedly in the system message buffer, which can be viewed using &man.dmesg.8;. Each open file, socket, or fifo uses one file descriptor. A large-scale production server may easily require many thousands of file descriptors, depending on the kind and number of services running concurrently. In older &os; releases, the default value of kern.maxfiles is derived from in the kernel configuration file. kern.maxfiles grows proportionally to the value of . When compiling a custom kernel, consider setting this kernel configuration option according to the use of the system. From this number, the kernel is given most of its pre-defined limits. Even though a production machine may not have 256 concurrent users, the resources needed may be similar to a high-scale web server. The read-only &man.sysctl.8; variable kern.maxusers is automatically sized at boot based on the amount of memory available in the system, and may be determined at run-time by inspecting the value of kern.maxusers. Some systems require larger or smaller values of kern.maxusers and values of 64, 128, and 256 are not uncommon. Going above 256 is not recommended unless a huge number of file descriptors is needed. Many of the tunable values set to their defaults by kern.maxusers may be individually overridden at boot-time or run-time in /boot/loader.conf. Refer to &man.loader.conf.5; and /boot/defaults/loader.conf for more details and some hints. In older releases, the system will auto-tune maxusers if it is set to 0. The auto-tuning algorithm sets maxusers equal to the amount of memory in the system, with a minimum of 32, and a maximum of 384.. When setting this option, set maxusers to at least 4, especially if the system runs &xorg; or is used to compile software. The most important table set by maxusers is the maximum number of processes, which is set to 20 + 16 * maxusers. If maxusers is set to 1, there can only be 36 simultaneous processes, including the 18 or so that the system starts up at boot time and the 15 or so used by &xorg;. Even a simple task like reading a manual page will start up nine processes to filter, decompress, and view it. Setting maxusers to 64 allows up to 1044 simultaneous processes, which should be enough for nearly all uses. If, however, the proc table full error is displayed when trying to start another program, or a server is running with a large number of simultaneous users, increase the number and rebuild. maxusers does not limit the number of users which can log into the machine. It instead sets various table sizes to reasonable values considering the maximum number of users on the system and how many processes each user will be running. <varname>kern.ipc.soacceptqueue</varname> kern.ipc.soacceptqueue The kern.ipc.soacceptqueue &man.sysctl.8; variable limits the size of the listen queue for accepting new TCP connections. The default value of 128 is typically too low for robust handling of new connections on a heavily loaded web server. For such environments, it is recommended to increase this value to 1024 or higher. A service such as &man.sendmail.8;, or Apache may itself limit the listen queue size, but will often have a directive in its configuration file to adjust the queue size. Large listen queues do a better job of avoiding Denial of Service (DoS) attacks. Network Limits The NMBCLUSTERS kernel configuration option dictates the amount of network Mbufs available to the system. A heavily-trafficked server with a low number of Mbufs will hinder performance. Each cluster represents approximately 2 K of memory, so a value of 1024 represents 2 megabytes of kernel memory reserved for network buffers. A simple calculation can be done to figure out how many are needed. A web server which maxes out at 1000 simultaneous connections where each connection uses a 6 K receive and 16 K send buffer, requires approximately 32 MB worth of network buffers to cover the web server. A good rule of thumb is to multiply by 2, so 2x32 MB / 2 KB = 64 MB / 2 kB = 32768. Values between 4096 and 32768 are recommended for machines with greater amounts of memory. Never specify an arbitrarily high value for this parameter as it could lead to a boot time crash. To observe network cluster usage, use with &man.netstat.1;. The kern.ipc.nmbclusters loader tunable should be used to tune this at boot time. Only older versions of &os; will require the use of the NMBCLUSTERS kernel &man.config.8; option. For busy servers that make extensive use of the &man.sendfile.2; system call, it may be necessary to increase the number of &man.sendfile.2; buffers via the NSFBUFS kernel configuration option or by setting its value in /boot/loader.conf (see &man.loader.8; for details). A common indicator that this parameter needs to be adjusted is when processes are seen in the sfbufa state. The &man.sysctl.8; variable kern.ipc.nsfbufs is read-only. This parameter nominally scales with kern.maxusers, however it may be necessary to tune accordingly. Even though a socket has been marked as non-blocking, calling &man.sendfile.2; on the non-blocking socket may result in the &man.sendfile.2; call blocking until enough struct sf_buf's are made available. <varname>net.inet.ip.portrange.*</varname> net.inet.ip.portrange.* The net.inet.ip.portrange.* &man.sysctl.8; variables control the port number ranges automatically bound to TCP and UDP sockets. There are three ranges: a low range, a default range, and a high range. Most network programs use the default range which is controlled by net.inet.ip.portrange.first and net.inet.ip.portrange.last, which default to 1024 and 5000, respectively. Bound port ranges are used for outgoing connections and it is possible to run the system out of ports under certain circumstances. This most commonly occurs when running a heavily loaded web proxy. The port range is not an issue when running a server which handles mainly incoming connections, such as a web server, or has a limited number of outgoing connections, such as a mail relay. For situations where there is a shortage of ports, it is recommended to increase net.inet.ip.portrange.last modestly. A value of 10000, 20000 or 30000 may be reasonable. Consider firewall effects when changing the port range. Some firewalls may block large ranges of ports, usually low-numbered ports, and expect systems to use higher ranges of ports for outgoing connections. For this reason, it is not recommended that the value of net.inet.ip.portrange.first be lowered. <literal>TCP</literal> Bandwidth Delay Product TCP Bandwidth Delay Product Limiting net.inet.tcp.inflight.enable TCP bandwidth delay product limiting can be enabled by setting the net.inet.tcp.inflight.enable &man.sysctl.8; variable to 1. This instructs the system to attempt to calculate the bandwidth delay product for each connection and limit the amount of data queued to the network to just the amount required to maintain optimum throughput. This feature is useful when serving data over modems, Gigabit Ethernet, high speed WAN links, or any other link with a high bandwidth delay product, especially when also using window scaling or when a large send window has been configured. When enabling this option, also set net.inet.tcp.inflight.debug to 0 to disable debugging. For production use, setting net.inet.tcp.inflight.min to at least 6144 may be beneficial. Setting high minimums may effectively disable bandwidth limiting, depending on the link. The limiting feature reduces the amount of data built up in intermediate route and switch packet queues and reduces the amount of data built up in the local host's interface queue. With fewer queued packets, interactive connections, especially over slow modems, will operate with lower Round Trip Times. This feature only effects server side data transmission such as uploading. It has no effect on data reception or downloading. Adjusting net.inet.tcp.inflight.stab is not recommended. This parameter defaults to 20, representing 2 maximal packets added to the bandwidth delay product window calculation. The additional window is required to stabilize the algorithm and improve responsiveness to changing conditions, but it can also result in higher &man.ping.8; times over slow links, though still much lower than without the inflight algorithm. In such cases, try reducing this parameter to 15, 10, or 5 and reducing net.inet.tcp.inflight.min to a value such as 3500 to get the desired effect. Reducing these parameters should be done as a last resort only. Virtual Memory <varname>kern.maxvnodes</varname> A vnode is the internal representation of a file or directory. Increasing the number of vnodes available to the operating system reduces disk I/O. Normally, this is handled by the operating system and does not need to be changed. In some cases where disk I/O is a bottleneck and the system is running out of vnodes, this setting needs to be increased. The amount of inactive and free RAM will need to be taken into account. To see the current number of vnodes in use: &prompt.root; sysctl vfs.numvnodes vfs.numvnodes: 91349 To see the maximum vnodes: &prompt.root; sysctl kern.maxvnodes kern.maxvnodes: 100000 If the current vnode usage is near the maximum, try increasing kern.maxvnodes by a value of 1000. Keep an eye on the number of vfs.numvnodes. If it climbs up to the maximum again, kern.maxvnodes will need to be increased further. Otherwise, a shift in memory usage as reported by &man.top.1; should be visible and more memory should be active. Adding Swap Space Sometimes a system requires more swap space. This section describes two methods to increase swap space: adding swap to an existing partition or new hard drive, and creating a swap file on an existing partition. For information on how to encrypt swap space, which options exist, and why it should be done, refer to . Swap on a New Hard Drive or Existing Partition Adding a new hard drive for swap gives better performance than using a partition on an existing drive. Setting up partitions and hard drives is explained in while discusses partition layouts and swap partition size considerations. Use swapon to add a swap partition to the system. For example: &prompt.root; swapon /dev/ada1s1b It is possible to use any partition not currently mounted, even if it already contains data. Using swapon on a partition that contains data will overwrite and destroy that data. Make sure that the partition to be added as swap is really the intended partition before running swapon. To automatically add this swap partition on boot, add an entry to /etc/fstab: /dev/ada1s1b none swap sw 0 0 See &man.fstab.5; for an explanation of the entries in /etc/fstab. More information about swapon can be found in &man.swapon.8;. Creating a Swap File These examples create a 64M swap file called /usr/swap0 instead of using a partition. Using swap files requires that the module needed by &man.md.4; has either been built into the kernel or has been loaded before swap is enabled. See for information about building a custom kernel. Creating a Swap File on &os; 10.<replaceable>X</replaceable> and Later Create the swap file: &prompt.root; dd if=/dev/zero of=/usr/swap0 bs=1m count=64 Set the proper permissions on the new file: &prompt.root; chmod 0600 /usr/swap0 Inform the system about the swap file by adding a line to /etc/fstab: md99 none swap sw,file=/usr/swap0,late 0 0 The &man.md.4; device md99 is used, leaving lower device numbers available for interactive use. Swap space will be added on system startup. To add swap space immediately, use &man.swapon.8;: &prompt.root; swapon -aL Creating a Swap File on &os; 9.<replaceable>X</replaceable> and Earlier Create the swap file, /usr/swap0: &prompt.root; dd if=/dev/zero of=/usr/swap0 bs=1m count=64 Set the proper permissions on /usr/swap0: &prompt.root; chmod 0600 /usr/swap0 Enable the swap file in /etc/rc.conf: swapfile="/usr/swap0" # Set to name of swap file Swap space will be added on system startup. To enable the swap file immediately, specify a free memory device. Refer to for more information about memory devices. &prompt.root; mdconfig -a -t vnode -f /usr/swap0 -u 0 && swapon /dev/md0 Power and Resource Management Hiten Pandya Written by Tom Rhodes It is important to utilize hardware resources in an efficient manner. Power and resource management allows the operating system to monitor system limits and to possibly provide an alert if the system temperature increases unexpectedly. An early specification for providing power management was the Advanced Power Management (APM) facility. APM controls the power usage of a system based on its activity. However, it was difficult and inflexible for operating systems to manage the power usage and thermal properties of a system. The hardware was managed by the BIOS and the user had limited configurability and visibility into the power management settings. The APM BIOS is supplied by the vendor and is specific to the hardware platform. An APM driver in the operating system mediates access to the APM Software Interface, which allows management of power levels. There are four major problems in APM. First, power management is done by the vendor-specific BIOS, separate from the operating system. For example, the user can set idle-time values for a hard drive in the APM BIOS so that, when exceeded, the BIOS spins down the hard drive without the consent of the operating system. Second, the APM logic is embedded in the BIOS, and it operates outside the scope of the operating system. This means that users can only fix problems in the APM BIOS by flashing a new one into the ROM, which is a dangerous procedure with the potential to leave the system in an unrecoverable state if it fails. Third, APM is a vendor-specific technology, meaning that there is a lot of duplication of efforts and bugs found in one vendor's BIOS may not be solved in others. Lastly, the APM BIOS did not have enough room to implement a sophisticated power policy or one that can adapt well to the purpose of the machine. The Plug and Play BIOS (PNPBIOS) was unreliable in many situations. PNPBIOS is 16-bit technology, so the operating system has to use 16-bit emulation in order to interface with PNPBIOS methods. &os; provides an APM driver as APM should still be used for systems manufactured at or before the year 2000. The driver is documented in &man.apm.4;. ACPI APM The successor to APM is the Advanced Configuration and Power Interface (ACPI). ACPI is a standard written by an alliance of vendors to provide an interface for hardware resources and power management. It is a key element in Operating System-directed configuration and Power Management as it provides more control and flexibility to the operating system. This chapter demonstrates how to configure ACPI on &os;. It then offers some tips on how to debug ACPI and how to submit a problem report containing debugging information so that developers can diagnosis and fix ACPI issues. Configuring <acronym>ACPI</acronym> In &os; the &man.acpi.4; driver is loaded by default at system boot and should not be compiled into the kernel. This driver cannot be unloaded after boot because the system bus uses it for various hardware interactions. However, if the system is experiencing problems, ACPI can be disabled altogether by rebooting after setting hint.acpi.0.disabled="1" in /boot/loader.conf or by setting this variable at the loader prompt, as described in . ACPI and APM cannot coexist and should be used separately. The last one to load will terminate if the driver notices the other is running. ACPI can be used to put the system into a sleep mode with acpiconf, the flag, and a number from 1 to 5. Most users only need 1 (quick suspend to RAM) or 3 (suspend to RAM). Option 5 performs a soft-off which is the same as running halt -p. Other options are available using sysctl. Refer to &man.acpi.4; and &man.acpiconf.8; for more information. Common Problems ACPI ACPI is present in all modern computers that conform to the ia32 (x86), ia64 (Itanium), and amd64 (AMD) architectures. The full standard has many features including CPU performance management, power planes control, thermal zones, various battery systems, embedded controllers, and bus enumeration. Most systems implement less than the full standard. For instance, a desktop system usually only implements bus enumeration while a laptop might have cooling and battery management support as well. Laptops also have suspend and resume, with their own associated complexity. An ACPI-compliant system has various components. The BIOS and chipset vendors provide various fixed tables, such as FADT, in memory that specify things like the APIC map (used for SMP), config registers, and simple configuration values. Additionally, a bytecode table, the Differentiated System Description Table DSDT, specifies a tree-like name space of devices and methods. The ACPI driver must parse the fixed tables, implement an interpreter for the bytecode, and modify device drivers and the kernel to accept information from the ACPI subsystem. For &os;, &intel; has provided an interpreter (ACPI-CA) that is shared with &linux; and NetBSD. The path to the ACPI-CA source code is src/sys/contrib/dev/acpica. The glue code that allows ACPI-CA to work on &os; is in src/sys/dev/acpica/Osd. Finally, drivers that implement various ACPI devices are found in src/sys/dev/acpica. ACPI problems For ACPI to work correctly, all the parts have to work correctly. Here are some common problems, in order of frequency of appearance, and some possible workarounds or fixes. If a fix does not resolve the issue, refer to for instructions on how to submit a bug report. Mouse Issues In some cases, resuming from a suspend operation will cause the mouse to fail. A known work around is to add hint.psm.0.flags="0x3000" to /boot/loader.conf. Suspend/Resume ACPI has three suspend to RAM (STR) states, S1-S3, and one suspend to disk state (STD), called S4. STD can be implemented in two separate ways. The S4BIOS is a BIOS-assisted suspend to disk and S4OS is implemented entirely by the operating system. The normal state the system is in when plugged in but not powered up is soft off (S5). Use sysctl hw.acpi to check for the suspend-related items. These example results are from a Thinkpad: hw.acpi.supported_sleep_state: S3 S4 S5 hw.acpi.s4bios: 0 Use acpiconf -s to test S3, S4, and S5. An of one (1) indicates S4BIOS support instead of S4 operating system support. When testing suspend/resume, start with S1, if supported. This state is most likely to work since it does not require much driver support. No one has implemented S2, which is similar to S1. Next, try S3. This is the deepest STR state and requires a lot of driver support to properly reinitialize the hardware. A common problem with suspend/resume is that many device drivers do not save, restore, or reinitialize their firmware, registers, or device memory properly. As a first attempt at debugging the problem, try: &prompt.root; sysctl debug.bootverbose=1 &prompt.root; sysctl debug.acpi.suspend_bounce=1 &prompt.root; acpiconf -s 3 This test emulates the suspend/resume cycle of all device drivers without actually going into S3 state. In some cases, problems such as losing firmware state, device watchdog time out, and retrying forever, can be captured with this method. Note that the system will not really enter S3 state, which means devices may not lose power, and many will work fine even if suspend/resume methods are totally missing, unlike real S3 state. Harder cases require additional hardware, such as a serial port and cable for debugging through a serial console, a Firewire port and cable for using &man.dcons.4;, and kernel debugging skills. To help isolate the problem, unload as many drivers as possible. If it works, narrow down which driver is the problem by loading drivers until it fails again. Typically, binary drivers like nvidia.ko, display drivers, and USB will have the most problems while Ethernet interfaces usually work fine. If drivers can be properly loaded and unloaded, automate this by putting the appropriate commands in /etc/rc.suspend and /etc/rc.resume. Try setting to 1 if the display is messed up after resume. Try setting longer or shorter values for to see if that helps. Try loading a recent &linux; distribution to see if suspend/resume works on the same hardware. If it works on &linux;, it is likely a &os; driver problem. Narrowing down which driver causes the problem will assist developers in fixing the problem. Since the ACPI maintainers rarely maintain other drivers, such as sound or ATA, any driver problems should also be posted to the &a.current.name; list and mailed to the driver maintainer. Advanced users can include debugging &man.printf.3;s in a problematic driver to track down where in its resume function it hangs. Finally, try disabling ACPI and enabling APM instead. If suspend/resume works with APM, stick with APM, especially on older hardware (pre-2000). It took vendors a while to get ACPI support correct and older hardware is more likely to have BIOS problems with ACPI. System Hangs Most system hangs are a result of lost interrupts or an interrupt storm. Chipsets may have problems based on boot, how the BIOS configures interrupts before correctness of the APIC (MADT) table, and routing of the System Control Interrupt (SCI). interrupt storms Interrupt storms can be distinguished from lost interrupts by checking the output of vmstat -i and looking at the line that has acpi0. If the counter is increasing at more than a couple per second, there is an interrupt storm. If the system appears hung, try breaking to DDB ( CTRL ALT ESC on console) and type show interrupts. APIC disabling When dealing with interrupt problems, try disabling APIC support with hint.apic.0.disabled="1" in /boot/loader.conf. Panics Panics are relatively rare for ACPI and are the top priority to be fixed. The first step is to isolate the steps to reproduce the panic, if possible, and get a backtrace. Follow the advice for enabling options DDB and setting up a serial console in or setting up a dump partition. To get a backtrace in DDB, use tr. When handwriting the backtrace, get at least the last five and the top five lines in the trace. Then, try to isolate the problem by booting with ACPI disabled. If that works, isolate the ACPI subsystem by using various values of . See &man.acpi.4; for some examples. System Powers Up After Suspend or Shutdown First, try setting hw.acpi.disable_on_poweroff="0" in /boot/loader.conf. This keeps ACPI from disabling various events during the shutdown process. Some systems need this value set to 1 (the default) for the same reason. This usually fixes the problem of a system powering up spontaneously after a suspend or poweroff. BIOS Contains Buggy Bytecode ACPI ASL Some BIOS vendors provide incorrect or buggy bytecode. This is usually manifested by kernel console messages like this: ACPI-1287: *** Error: Method execution failed [\\_SB_.PCI0.LPC0.FIGD._STA] \\ (Node 0xc3f6d160), AE_NOT_FOUND Often, these problems may be resolved by updating the BIOS to the latest revision. Most console messages are harmless, but if there are other problems, like the battery status is not working, these messages are a good place to start looking for problems. Overriding the Default <acronym>AML</acronym> The BIOS bytecode, known as ACPI Machine Language (AML), is compiled from a source language called ACPI Source Language (ASL). The AML is found in the table known as the Differentiated System Description Table (DSDT). ACPI ASL The goal of &os; is for everyone to have working ACPI without any user intervention. Workarounds are still being developed for common mistakes made by BIOS vendors. The µsoft; interpreter (acpi.sys and acpiec.sys) does not strictly check for adherence to the standard, and thus many BIOS vendors who only test ACPI under &windows; never fix their ASL. &os; developers continue to identify and document which non-standard behavior is allowed by µsoft;'s interpreter and replicate it so that &os; can work without forcing users to fix the ASL. To help identify buggy behavior and possibly fix it manually, a copy can be made of the system's ASL. To copy the system's ASL to a specified file name, use acpidump with , to show the contents of the fixed tables, and , to disassemble the AML: &prompt.root; acpidump -td > my.asl Some AML versions assume the user is running &windows;. To override this, set hw.acpi.osname="Windows 2009" in /boot/loader.conf, using the most recent &windows; version listed in the ASL. Other workarounds may require my.asl to be customized. If this file is edited, compile the new ASL using the following command. Warnings can usually be ignored, but errors are bugs that will usually prevent ACPI from working correctly. &prompt.root; iasl -f my.asl Including forces creation of the AML, even if there are errors during compilation. Some errors, such as missing return statements, are automatically worked around by the &os; interpreter. The default output filename for iasl is DSDT.aml. Load this file instead of the BIOS's buggy copy, which is still present in flash memory, by editing /boot/loader.conf as follows: acpi_dsdt_load="YES" acpi_dsdt_name="/boot/DSDT.aml" Be sure to copy DSDT.aml to /boot, then reboot the system. If this fixes the problem, send a &man.diff.1; of the old and new ASL to &a.acpi.name; so that developers can work around the buggy behavior in acpica. Getting and Submitting Debugging Info Nate Lawson Written by Peter Schultz With contributions from Tom Rhodes ACPI problems ACPI debugging The ACPI driver has a flexible debugging facility. A set of subsystems and the level of verbosity can be specified. The subsystems to debug are specified as layers and are broken down into components (ACPI_ALL_COMPONENTS) and ACPI hardware support (ACPI_ALL_DRIVERS). The verbosity of debugging output is specified as the level and ranges from just report errors (ACPI_LV_ERROR) to everything (ACPI_LV_VERBOSE). The level is a bitmask so multiple options can be set at once, separated by spaces. In practice, a serial console should be used to log the output so it is not lost as the console message buffer flushes. A full list of the individual layers and levels is found in &man.acpi.4;. Debugging output is not enabled by default. To enable it, add options ACPI_DEBUG to the custom kernel configuration file if ACPI is compiled into the kernel. Add ACPI_DEBUG=1 to /etc/make.conf to enable it globally. If a module is used instead of a custom kernel, recompile just the acpi.ko module as follows: &prompt.root; cd /sys/modules/acpi/acpi && make clean && make ACPI_DEBUG=1 Copy the compiled acpi.ko to /boot/kernel and add the desired level and layer to /boot/loader.conf. The entries in this example enable debug messages for all ACPI components and hardware drivers and output error messages at the least verbose level: debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS" debug.acpi.level="ACPI_LV_ERROR" If the required information is triggered by a specific event, such as a suspend and then resume, do not modify /boot/loader.conf. Instead, use sysctl to specify the layer and level after booting and preparing the system for the specific event. The variables which can be set using sysctl are named the same as the tunables in /boot/loader.conf. ACPI problems Once the debugging information is gathered, it can be sent to &a.acpi.name; so that it can be used by the &os; ACPI maintainers to identify the root cause of the problem and to develop a solution. Before submitting debugging information to this mailing list, ensure the latest BIOS version is installed and, if available, the embedded controller firmware version. When submitting a problem report, include the following information: Description of the buggy behavior, including system type, model, and anything that causes the bug to appear. Note as accurately as possible when the bug began occurring if it is new. The output of dmesg after running boot -v, including any error messages generated by the bug. The dmesg output from boot -v with ACPI disabled, if disabling ACPI helps to fix the problem. Output from sysctl hw.acpi. This lists which features the system offers. The URL to a pasted version of the system's ASL. Do not send the ASL directly to the list as it can be very large. Generate a copy of the ASL by running this command: &prompt.root; acpidump -dt > name-system.asl Substitute the login name for name and manufacturer/model for system. For example, use njl-FooCo6000.asl. Most &os; developers watch the &a.current;, but one should submit problems to &a.acpi.name; to be sure it is seen. Be patient when waiting for a response. If the bug is not immediately apparent, submit a PR using &man.send-pr.1;. When entering a PR, include the same information as requested above. This helps developers to track the problem and resolve it. Do not send a PR without emailing &a.acpi.name; first as it is likely that the problem has been reported before. References More information about ACPI may be found in the following locations: The &os; ACPI Mailing List Archives (https://lists.freebsd.org/pipermail/freebsd-acpi/) The ACPI 2.0 Specification (http://acpi.info/spec.htm) &man.acpi.4;, &man.acpi.thermal.4;, &man.acpidump.8;, &man.iasl.8;, and &man.acpidb.8;