          Frequently Asked Questions for FreeBSD 8.X, and 9.X

  The FreeBSD Documentation Project

   Copyright (c) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
   2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
   The FreeBSD Documentation Project

   This is the FAQ for FreeBSD versions 8.X and 9.X. 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, please feel free to
   mail them to the FreeBSD documentation project mailing list.

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     --------------------------------------------------------------

   Table of Contents

   1 Introduction

   2 Documentation and Support

   3 Installation

   4 Hardware Compatibility

                4.1 General

                4.2 Architectures and Processors

                4.3 Hard Drives, Tape Drives, and CD and DVD Drives

                4.4 Keyboards and Mice

                4.5 Other Hardware

   5 Troubleshooting

   6 User Applications

   7 Kernel Configuration

   8 Disks, File Systems, and Boot Loaders

                8.1 ZFS

   9 System Administration

   10 The X Window System and Virtual Consoles

   11 Networking

   12 Security

   13 PPP

   14 Serial Communications

   15 Miscellaneous Questions

   16 The FreeBSD Funnies

   17 Advanced Topics

   18 Acknowledgments

   Bibliography

   List of Tables

   3-1. Maximum File Sizes

   List of Examples

   10-1. "InputDevice" Section for Wheeled Mouse in Xorg
   Configuration File

   10-2. ".emacs" Example for Naive Page Scrolling with Wheeled Mouse
   (optional)

     --------------------------------------------------------------

                         Chapter 1 Introduction

   1.1. What is FreeBSD?

   1.2. What is the goal of the FreeBSD Project?

   1.3. Does the FreeBSD license have any restrictions?

   1.4. Can FreeBSD replace my current operating system?

   1.5. Why is it called FreeBSD?

   1.6. What are the differences between FreeBSD and NetBSD, OpenBSD,
   and other open source BSD operating systems?

   1.7. What is the latest version of FreeBSD?

   1.8. What is FreeBSD-CURRENT?

   1.9. What is the FreeBSD-STABLE concept?

   1.10. When are FreeBSD releases made?

   1.11. Who is responsible for FreeBSD?

   1.12. Where can I get FreeBSD?

   1.13. How do I access the Problem Report database?

   1.1. What is FreeBSD?

   FreeBSD 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(TM),
   known as "386BSD", though very little of the 386BSD code remains.

   FreeBSD is used by companies, Internet Service Providers,
   researchers, computer professionals, students and home users all
   over the world in their work, education and recreation.

   For more detailed information on FreeBSD, please see the FreeBSD
   Handbook.

   1.2. What is the goal of the FreeBSD Project?

   The goal of the FreeBSD Project is to provide a stable and fast
   general purpose operating system that may be used for any purpose
   without strings attached.

   1.3. Does the FreeBSD license have any restrictions?

   Yes. Those restrictions do not control how you use the code,
   merely how you treat the FreeBSD Project itself. If you have
   serious license concerns, read the actual license. For the simply
   curious, the license 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 FreeBSD license whenever
   possible.

   1.4. Can FreeBSD replace my current operating system?

   For most people, yes. But this question is not quite that
   cut-and-dried.

   Most people do not actually use an operating system. They use
   applications. The applications are what really use the operating
   system. FreeBSD is designed to provide a robust and full-featured
   environment for applications. It supports a wide variety of web
   browsers, office suites, email readers, graphics programs,
   programming environments, network servers, and just about
   everything else you might want. Most of these applications can be
   managed through the Ports Collection.

   If you need to use an application that is only available on one
   operating system, you simply cannot replace that operating system.
   Chances are there is a very similar application on FreeBSD,
   however. If you want a solid office or Internet server, a reliable
   workstation, or just the ability to do your job without
   interruptions, FreeBSD will almost certainly do everything you
   need. Many computer users across the world, including both novices
   and experienced UNIX(R) administrators, use FreeBSD as their only
   desktop operating system.

   If you are migrating to FreeBSD from some other UNIX environment,
   you already know most of what you need to. If your background is
   in graphic-driven operating systems such as Windows(R) and
   Mac OS(R), you may be interested in using PC-BSD, a FreeBSD based
   distribution, instead. If you have not used UNIX before expect to
   invest additional time learning the UNIX way of doing things. This
   FAQ and the FreeBSD Handbook are excellent places to start.

   1.5. Why is it called FreeBSD?

   * It may be used free of charge, even by commercial users.

   * Full source for the operating system is freely available, and
     the minimum possible restrictions have been placed upon its use,
     distribution and incorporation into other work (commercial or
     non-commercial).

   * Anyone who has an improvement or bug fix is free to submit their
     code and have it added to the source tree (subject to one or two
     obvious provisions).

   It is worth pointing out that the word "free" is being used in two
   ways here, one meaning "at no cost", the other meaning "you can do
   whatever you like". Apart from one or two things you cannot do
   with the FreeBSD code, for example pretending you wrote it, you
   can really do whatever you like with it.

   1.6. What are the differences between FreeBSD and NetBSD, OpenBSD,
   and other open source BSD operating systems?

   James Howard wrote a good explanation of the history and
   differences between the various projects, called The BSD Family
   Tree which goes a fair way to answering this question. Some of the
   information is out of date, but the history portion in particular
   remains accurate.

   Most of the BSDs share patches and code, even today. All of the
   BSDs have common ancestry.

   The design goals of FreeBSD are described in Q: 1.2., 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 ssh(1) and pf(4), which have both been
       ported to FreeBSD.

     * NetBSD aims to be easily ported to other hardware platforms.

     * DragonFly BSD is a fork of FreeBSD 4.8 that has since
       developed many interesting features of its own, including the
       HAMMER file system and support for user-mode "vkernels".

   1.7. What is the latest version of FreeBSD?

   At any point in the development of FreeBSD, there can be multiple
   parallel branches. 9.X releases are made from the 9-STABLE branch,
   and 8.X releases are made from the 8-STABLE branch.

   Up until the release of 9.0, the 8.X series was the one known as
   -STABLE. However, as of 10.X, the 8.X. branch will be designated
   for an "extended support" status and receive only fixes for major
   problems, such as security-related fixes.

   Version 9.1 is the latest release from the 9-STABLE branch; it was
   released in December 2012. Version 8.4 is the latest release from
   the 8-STABLE branch; it was released in April 2013.

   Briefly, -STABLE is aimed at the ISP, corporate user, or any user
   who wants stability and a minimal number of changes compared to
   the new (and possibly unstable) features of the latest -CURRENT
   snapshot. Releases can come from either branch, but -CURRENT
   should only be used if you are prepared for its increased
   volatility (relative to -STABLE, that is).

   Releases are made every few months. While many people stay more
   up-to-date with the FreeBSD sources (see the questions on
   FreeBSD-CURRENT and FreeBSD-STABLE) than that, doing so is more of
   a commitment, as the sources are a moving target.

   More information on FreeBSD releases can be found on the Release
   Engineering page on the FreeBSD Web site.

   1.8. What is FreeBSD-CURRENT?

   FreeBSD-CURRENT is the development version of the operating
   system, which will in due course become the new FreeBSD-STABLE
   branch. As such, it is really only of interest to developers
   working on the system and die-hard hobbyists. See the relevant
   section in the Handbook for details on running -CURRENT.

   If you are not familiar with FreeBSD you should not use
   FreeBSD-CURRENT. This branch sometimes evolves quite quickly and
   due to mistake can be un-buildable at times. People that use
   FreeBSD-CURRENT are expected to be able to analyze, debug, and
   report problems.

   FreeBSD 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 you want to run a stable
   and fully tested system, you will have to stick to full releases,
   or use the -STABLE snapshots.

   Snapshot releases are directly available from snapshot.

   Official snapshots are generated on a regular basis for all
   actively developed branches.

   1.9. What is the FreeBSD-STABLE concept?

   Back when FreeBSD 2.0.5 was released, FreeBSD development branched
   in two. One branch was named -STABLE, one -CURRENT. FreeBSD-STABLE
   is intended for Internet Service Providers and other commercial
   enterprises for whom sudden shifts or experimental features are
   quite undesirable. It receives only well-tested bug fixes and
   other small incremental enhancements. FreeBSD-CURRENT, on the
   other hand, has been one unbroken line since 2.0 was released,
   leading towards 9.1-RELEASE and beyond. For more detailed
   information on branches see "FreeBSD 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.

   9.1-STABLE is the actively developed -STABLE branch. The latest
   release on the 9.1-STABLE branch is 9.1-RELEASE, which was
   released in December 2012.

   The 10-CURRENT branch is the actively developed -CURRENT branch
   toward the next generation of FreeBSD. See What is
   FreeBSD-CURRENT? for more information on this branch.

   1.10. When are FreeBSD releases made?

   The Release Engineering Team <re@FreeBSD.org> releases a new major
   version of FreeBSD about every 18 months and a new minor version
   about every 8 months, on average. Release dates are announced well
   in advance, so that the people working on the system know when
   their projects need to be finished and tested. A testing period
   precedes each release, to ensure that the addition of new features
   does not compromise the stability of the release. Many users
   regard this caution as one of the best things about FreeBSD, even
   though waiting for all the latest goodies to reach -STABLE can be
   a little frustrating.

   More information on the release engineering process (including a
   schedule of upcoming releases) can be found on the release
   engineering pages on the FreeBSD Web site.

   For people who need or want a little more excitement, binary
   snapshots are made daily as discussed above.

   1.11. Who is responsible for FreeBSD?

   The key decisions concerning the FreeBSD project, such as the
   overall direction of the project and who is allowed to add code to
   the source tree, are made by a 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 FreeBSD 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.

   1.12. Where can I get FreeBSD?

   Every significant release of FreeBSD is available via anonymous
   FTP from the FreeBSD FTP site:

     * The latest 9-STABLE release, 9.1-RELEASE can be found in the
       9.1-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 8-STABLE release, 8.4-RELEASE can be found in the
       8.4-RELEASE directory.

   Information about obtaining FreeBSD on CD, DVD, and other media
   can be found in the Handbook.

   1.13. 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 send-pr(1) command can be used to submit problem reports and
   change requests via electronic mail. Alternatively, the web-based
   problem report submission interface can be used to submit problem
   reports through a web browser.

   Before submitting a problem report, please read Writing FreeBSD
   Problem Reports, an article on how to write good problem reports.

     --------------------------------------------------------------

                  Chapter 2 Documentation and Support

   2.1. What good books are there about FreeBSD?

   2.2. Is the documentation available in other formats, such as
   plain text (ASCII), or PostScript(R)?

   2.3. Where do I find info on the FreeBSD mailing lists? What
   FreeBSD news groups are available?

   2.4. Are there FreeBSD IRC (Internet Relay Chat) channels?

   2.5. Are there any web based forums to discuss FreeBSD?

   2.6. Where can I get commercial FreeBSD training and support?

   2.1. What good books are there about FreeBSD?

   The project produces a wide range of documentation, available
   online from this link: http://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.

   2.2. Is the documentation available in other formats, such as
   plain text (ASCII), or PostScript(R)?

   Yes. The documentation is available in a number of different
   formats and compression schemes on the FreeBSD 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 you will find under /usr/share/locale on your
       FreeBSD system. The current languages and encodings that we
       have for documentation 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.GB2312      Simplified Chinese (China, GB2312 encoding)  
       zh_TW.Big5        Traditional Chinese (Taiwan, Big5 encoding)  

         Note: Some documents may not be available in all languages.

     * The document's format. We produce the documentation in a
       number of different output formats. Each format has its own
       advantages and disadvantages. Some formats are better suited
       for online reading, while others are meant to be aesthetically
       pleasing when printed on paper. Having the documentation
       available in any of these formats ensures that our readers
       will be able to read the parts they are interested in, either
       on their monitor, or on paper after printing the documents.
       The currently available formats are:

         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         Microsoft's Rich Text Format                       
       txt         Plain text                                         

         Note: Page numbers are not automatically updated when
         loading Rich Text Format into Word. Press Ctrl+A, Ctrl+End,
         F9 after loading the document, to update the page numbers.

     * The compression and packaging scheme.

         1. Where the format is html-split, the files are bundled up
            using tar(1). The resulting .tar file is then compressed
            using the compression schemes detailed in the next point.

         2. All the other formats generate one file, called
            type.format (i.e., article.pdf, book.html, and so on).

            These files are then compressed using either the zip or
            bz2 compression schemes. 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 that you want
   to download, you will have to download the compressed files
   yourself, uncompress them, and then copy the appropriate documents
   into place.

   For example, the split HTML version of the FAQ, compressed using
   bzip2(1), can be found in
   doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2 To download
   and uncompress that file you would have to do this:

 # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2
 # tar xvf book.html-split.tar.bz2

   If the file is compressed, tar will automatically detect the
   appropriate format and decompress it correctly. You will be left
   with 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. You can
   then copy or move these to their final location as necessary.

   2.3. Where do I find info on the FreeBSD mailing lists? What
   FreeBSD news groups are available?

   You can find full information in the Handbook entry on
   mailing-lists and the Handbook entry on newsgroups.

   2.4. Are there FreeBSD IRC (Internet Relay Chat) channels?

   Yes, most major IRC networks host a FreeBSD chat channel:

     * Channel #FreeBSDhelp on EFNet is a channel dedicated to
       helping FreeBSD users. They are much more sympathetic to
       questions than #FreeBSD is.

     * 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
       FreeBSD questions. We are good about helping you understand
       the basics, referring to the Handbook whenever possible, and
       directing you where to learn more about the topic you need
       help with. We are a primarily English speaking channel, though
       we have users from all over the world. If you would like to
       speak in your native language, try to ask the question in
       English and then relocate to another channel ##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 oriented
       channel dedicated to helping FreeBSD users. This is also good
       place for non-technical discussions.

     * Channel #bsdchat on Freenode is a Traditional-Chinese (UTF-8
       encoding) language oriented channel dedicated to helping
       FreeBSD users. This is also good place for non-technical
       discussions.

   The FreeBSD wiki has a good list of IRC channels.

   Each of these channels are distinct and are not connected to each
   other. Their chat styles also differ, so you may need to try each
   to find one suited to your chat style. As with all types of IRC
   traffic, if you are easily offended or cannot deal with lots of
   young people (and more than a few older ones) doing the verbal
   equivalent of jello wrestling, do not even bother with it.

   2.5. Are there any web based forums to discuss FreeBSD?

   The official FreeBSD forums are located at
   http://forums.FreeBSD.org/.

   2.6. Where can I get commercial FreeBSD training and support?

   iXsystems, Inc., parent company of the FreeBSD Mall, provides
   commercial FreeBSD and PC-BSD software support, in addition to
   FreeBSD development and tuning solutions.

   BSD Certification Group, Inc. provides system administration
   certifications for DragonFly BSD, FreeBSD, NetBSD, OpenBSD. If you
   are interested in them, visit their site.

   Any other organizations providing training and support should
   contact the Project to be listed here.

     --------------------------------------------------------------

                         Chapter 3 Installation

   Nik Clayton

   3.1. Which platform should I download? I have a 64 bit capable
   Intel(R) CPU, but I only see amd64.

   3.2. Which file do I download to get FreeBSD?

   3.3. What do I do if the images do not fit on a single disk?

   3.4. Where are the instructions for installing FreeBSD?

   3.5. What do I need to run FreeBSD?

   3.6. How can I make my own custom release or install disk?

   3.7. Can Windows co-exist with FreeBSD?

   3.8. Another operating system destroyed my Boot Manager. How do I
   get it back?

   3.9. I booted from my ATAPI CD-ROM, but the install program says
   no CD-ROM is found. Where did it go?

   3.10. Do I need to install the source?

   3.11. Do I need to build a kernel?

   3.12. Should I use DES, Blowfish, or MD5 passwords and how do I
   specify which form my users receive?

   3.13. What are the limits for memory?

   3.14. What are the limits for FFS file systems?

   3.15. Why do I get an error message, "readin failed" after
   compiling and booting a new kernel?

   3.16. Is there a tool to perform post-installation configuration
   tasks?

   3.1. Which platform should I download? I have a 64 bit capable
   Intel(R) CPU, but I only see amd64.

   amd64 is the term FreeBSD uses for 64-bit compatible x86
   architectures (also known as "x86-64" or "x64"). Most modern
   computers should use amd64. Older hardware should use i386. If you
   are installing on a non-x86-compatible architecture select the
   platform which best matches the architecture you are using.

   3.2. Which file do I download to get FreeBSD?

   On the Getting FreeBSD page select [iso] next to the architecture
   you want to use.

   Any of the following can be used:

       file                          description                      
   disc1.iso    Contains enough to install FreeBSD 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 FreeBSD.           

   pc98 users require these floppy images: floppies/boot.flp,
   floppies/kern1.flp, floppies/kern2.flp, and floppies/mfsroot1.flp.
   These images need to be written onto floppies by tools like dd(1).

   Full instructions on this procedure and a little bit more about
   installation issues in general can be found in the Handbook entry
   on installing FreeBSD.

   3.3. What do I do if the images do not fit on a single disk?

   Common mistakes when preparing the boot media are:

     * 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 of the
       downloaded boot image: if it is not exactly that on the
       server, then the download process is suspect.

       To workaround: type binary at the FTP command prompt after
       getting connected to the server and before starting the
       download of the image.

     * Using the DOS copy command (or equivalent GUI tool) to
       transfer the boot image to floppy.

       Programs like copy will not work as the boot image has been
       created to be booted into directly. The image has the complete
       content of the floppy, track for track, and is not meant to be
       placed on the floppy as a regular file. You have to transfer
       it to the floppy "raw", using the low-level tools (e.g.,
       fdimage or rawrite) described in the installation guide to
       FreeBSD.

   3.4. Where are the instructions for installing FreeBSD?

   Installation instructions for versions since FreeBSD 9.0 can be
   found at Handbook entry on installing FreeBSD. Older instructions
   can be found in the legacy entry on installing FreeBSD.

   3.5. What do I need to run FreeBSD?

   For FreeBSD you will need a 486 or better PC, with 64 MB or more
   of RAM and at least 1 GB of hard disk space.

   See also Chapter 4.

   3.6. How can I make my own custom release or install disk?

   Customized FreeBSD installation media can be created by building a
   custom release. Follow the instructions in the Release Engineering
   article.

   3.7. Can Windows co-exist with FreeBSD?

   If Windows is installed first, then yes. FreeBSD's boot manager
   will then manage to boot Windows and FreeBSD. If you install
   Windows second, it will boorishly overwrite your boot manager
   without even asking. If that happens, see the next section.

   3.8. Another operating system destroyed my Boot Manager. How do I
   get it back?

   This depends on what boot manager you have installed. The FreeBSD
   boot selection menu (likely what you are using if you end up in
   this situation) can be reinstalled using boot0cfg(8). For example,
   to restore the boot menu onto the disk ada0:

 # boot0cfg -B ada0

   The non-interactive MBR bootloader can be installed using
   gpart(8):

 # gpart bootcode -b /boot/mbr ada0

   For more complex situations, including GPT disks, see gpart(8).

   3.9. I booted from my ATAPI CD-ROM, but the install program says
   no CD-ROM is found. Where did it go?

   The usual cause of this problem is a mis-configured CD-ROM drive.
   Many PCs now ship with the CD-ROM as the slave device on the
   secondary IDE controller, with no master device on that
   controller. This is illegal according to the ATAPI specification,
   but Windows plays fast and loose with the specification, and the
   BIOS ignores it when booting. This is why the BIOS was able to see
   the CD-ROM to boot from it, but why FreeBSD cannot see it to
   complete the install.

   Reconfigure your system so that the CD-ROM is either the master
   device on the IDE controller it is attached to, or make sure that
   it is the slave on an IDE controller that also has a master
   device.

   3.10. 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.

   3.11. Do I need to build a kernel?

   Usually not. The supplied GENERIC kernel contains the drivers an
   ordinary computer will need. freebsd-update(8), the FreeBSD binary
   upgrade tool, cannot upgrade custom kernels, another reason to
   stick with the GENERIC kernel when possible. For computers with
   very limited RAM, such as embedded systems, it may be worthwhile
   to build a smaller custom kernel containing just the required
   drivers.

   3.12. Should I use DES, Blowfish, or MD5 passwords and how do I
   specify which form my users receive?

   FreeBSD 7 and 8 use MD5 password hashing by default. Recent
   versions of FreeBSD use SHA512 by default. These are believed to
   be more secure than the traditional UNIX password format, which
   used a scheme based on the DES algorithm. DES passwords are still
   available if you need to share your password file with legacy
   operating systems which still use the less secure password format.
   FreeBSD also allows you to use 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 login.conf(5) manual page for more
   information about login capabilities.

   3.13. What are the limits for memory?

   Memory limits depend on the platform used. On a standard i386
   install, the limit is 4 GB but more memory can be supported
   through pae(4). See instructions for using 4 GB or more memory on
   i386.

   FreeBSD/pc98 has a limit of 4 GB memory, and PAE can not be used
   with it. Other architectures supported by FreeBSD have much higher
   theoretical limits on maximum memory (many terabytes).

   3.14. What are the limits for FFS file systems?

   For FFS file systems, the maximum theoretical limit is 8 TB (2 G
   blocks), or 16 TB for the default block size of 8 KB. In practice,
   there is a soft limit of 1 TB, but with modifications file systems
   with 4 TB are possible (and exist).

   The maximum size of a single FFS file is approximately 1 G blocks,
   or 4 TB with a block size of 4 KB.

   Table 3-1. Maximum File Sizes

   +-----------------------------------------+
   | FS Block Size |   Works   | Should Work |
   |---------------+-----------+-------------|
   | 4 KB          | > 4 GB    | 4 TB - 1    |
   |---------------+-----------+-------------|
   | 8 KB          | > 32 GB   | 32 TB - 1   |
   |---------------+-----------+-------------|
   | 16 KB         | > 128 GB  | 32 TB - 1   |
   |---------------+-----------+-------------|
   | 32 KB         | > 512 GB  | 64 TB - 1   |
   |---------------+-----------+-------------|
   | 64 KB         | > 2048 GB | 128 TB - 1  |
   +-----------------------------------------+

   When the FS block size is 4 KB, triple indirect blocks work and
   everything should be limited by the maximum FS block number that
   can be represented using triple indirect blocks (approx.
   10243 + 10242 + 1024), but everything is limited by a (wrong)
   limit of 1 G - 1 on FS block numbers. The limit on FS block
   numbers should be 2 G - 1. There are some bugs for FS block
   numbers near 2 G - 1, but such block numbers are unreachable when
   the FS block size is 4 KB.

   For block sizes of 8 KB and larger, everything should be limited
   by the 2 G - 1 limit on FS block numbers, but is actually limited
   by the 1 G - 1 limit on FS block numbers. Using the correct limit
   of 2 G - 1 blocks does cause problems.

   3.15. Why do I get an error message, "readin failed" after
   compiling and booting a new kernel?

   Because your world and kernel are out of sync. This is not
   supported. Be sure you use make buildworld and make buildkernel to
   update your kernel.

   You can boot by specifying the kernel directly at the second
   stage, pressing any key when the | shows up before loader is
   started.

   3.16. Is there a tool to perform post-installation configuration
   tasks?

   Yes, HEAD users can set WITH_BSDCONFIG in /etc/src.conf. Users of
   9.X and higher may also install sysutils/bsdconfig.

     --------------------------------------------------------------

                    Chapter 4 Hardware Compatibility

4.1 General

   4.1.1. I want to get a piece of hardware for my FreeBSD system.
   Which model/brand/type is best?

   4.1.2. Does FreeBSD support more than 4 GB of memory (RAM)? More
   than 16 GB? More than 48 GB?

   4.1.3. Why does FreeBSD report less than 4 GB memory when
   installed on an i386 machine?

   4.1.1. I want to get a piece of hardware for my FreeBSD system.
   Which model/brand/type is best?

   This is discussed continually on the FreeBSD mailing lists. Since
   hardware changes so quickly, however, we expect this. We still
   strongly recommend that you read through the Hardware Notes for
   FreeBSD 9.1 or 8.4 and search the mailing list archives before
   asking about the latest and greatest hardware. Chances are a
   discussion about the type of hardware you are looking for took
   place just last week.

   If you are looking for a laptop, check the FreeBSD laptop computer
   mailing list archives. Otherwise, you probably want the archives
   for the FreeBSD general questions mailing list, or possibly a
   specific mailing list for a particular hardware type.

   4.1.2. Does FreeBSD support more than 4 GB of memory (RAM)? More
   than 16 GB? More than 48 GB?

   Yes. FreeBSD as an operating system generally supports as much
   physical memory (RAM) as the platform it is running on does. Keep
   in mind that different platforms have different limits for memory;
   for example i386 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. AMD64 platforms currently
   deployed support up to 1 TB of physical memory.

   4.1.3. Why does FreeBSD 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 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 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. If you
   wish to create your own kernel configuration file, you can enable
   PAE by adding the following line to your configuration:

 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.
   FreeBSD supports AMD64 and it is recommended that this version of
   FreeBSD be used instead of the i386 version if 4 GB or more memory
   is required.

     --------------------------------------------------------------

4.2 Architectures and Processors

   4.2.1. Does FreeBSD support architectures other than the x86?

   4.2.2. Does FreeBSD support Symmetric Multiprocessing (SMP)?

   4.2.3. What is microcode? How do I install Intel CPU microcode
   updates?

   4.2.1. Does FreeBSD support architectures other than the x86?

   Yes. FreeBSD divides support into multiple tiers. Tier 1
   architectures, such as i386 or amd64; are fully supported. Tiers 2
   and 3 are supported on an if-possible 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.

   4.2.2. Does FreeBSD support Symmetric Multiprocessing (SMP)?

   Symmetric multi-processor (SMP) systems are generally supported by
   FreeBSD, although in some cases, BIOS or motherboard bugs may
   generate some problems.

   FreeBSD will take advantage of HyperThreading (HTT) support on
   Intel CPUs that support this feature. A kernel with the options
   SMP option, enabled by default, will automatically detect the
   additional logical processors.

   smp(4) has more details.

   4.2.3. What is microcode? How do I install Intel CPU microcode
   updates?

   Microcode is a method of programmatically implementating 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

     --------------------------------------------------------------

4.3 Hard Drives, Tape Drives, and CD and DVD Drives

   4.3.1. What kind of hard drives does FreeBSD support?

   4.3.2. Which SCSI or SAS controllers are supported?

   4.3.3. What types of tape drives are supported?

   4.3.4. Does FreeBSD support tape changers?

   4.3.5. Which CD-ROM drives are supported by FreeBSD?

   4.3.6. Which CD-RW drives are supported by FreeBSD?

   4.3.1. What kind of hard drives does FreeBSD support?

   FreeBSD 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.

   4.3.2. Which SCSI or SAS controllers are supported?

   See the complete list in the Hardware Notes for FreeBSD 9.1 or
   8.4.

   4.3.3. What types of tape drives are supported?

   FreeBSD supports SCSI and QIC-36 (with a QIC-02 interface). This
   includes 8-mm (aka Exabyte) and DAT drives.

   Some of the early 8-mm drives are not quite compatible with
   SCSI-2, and may not work well with FreeBSD.

   4.3.4. Does FreeBSD support tape changers?

   FreeBSD supports SCSI changers using the ch(4) device and the
   chio(1) command. The details of how you actually control the
   changer can be found in the chio(1) manual page.

   If you are not using AMANDA or some other product that already
   understands changers, remember that they only know how to move a
   tape from one point to another, so you need to keep track of which
   slot a tape is in, and which slot the tape currently in the drive
   needs to go back to.

   4.3.5. Which CD-ROM drives are supported by FreeBSD?

   Any SCSI drive connected to a supported controller is supported.
   Most ATAPI compatible IDE CD-ROMs are supported.

   4.3.6. Which CD-RW drives are supported by FreeBSD?

   FreeBSD supports any ATAPI-compatible IDE CD-R or CD-RW drive. See
   burncd(8) for details.

   FreeBSD also supports any SCSI CD-R or CD-RW drives. Install and
   use cdrecord from the ports or packages system, and make sure that
   you have the pass device compiled in your kernel.

     --------------------------------------------------------------

4.4 Keyboards and Mice

   4.4.1. Is it possible to use a mouse in any way outside the X
   Window system?

   4.4.2. How do I cut and paste text with a mouse in the text
   console?

   4.4.3. My mouse has a fancy wheel and buttons. Can I use them in
   FreeBSD?

   4.4.4. How do I use my delete key in sh and csh?

   4.4.1. Is it possible to use a mouse in any way outside the X
   Window system?

   If you are using the default console driver, syscons(4), you can
   use a mouse pointer in text consoles to cut & paste text. Run the
   mouse daemon, moused(8), and turn on the mouse pointer in the
   virtual console:

 # moused -p /dev/xxxx -t yyyy
 # vidcontrol -m on

   Where xxxx is the mouse device name and yyyy is a protocol type
   for the mouse. The mouse daemon can automatically determine the
   protocol type of most mice, except old serial mice. Specify the
   auto protocol to invoke automatic detection. If automatic
   detection does not work, see the moused(8) manual page for a list
   of supported protocol types.

   If you have a PS/2 mouse, just add moused_enable="YES" to
   /etc/rc.conf to start the mouse daemon at boot-time. Additionally,
   if you would like 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.

   4.4.2. 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 you get the mouse daemon
   running (see 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 your mouse does not have a middle button, you may wish to
   emulate one or remap buttons using mouse daemon options. See the
   moused(8) manual page for details.

   4.4.3. My mouse has a fancy wheel and buttons. Can I use them in
   FreeBSD?

   The answer is, unfortunately, "It depends". These mice with
   additional features require specialized driver in most cases.
   Unless the mouse device driver or the user program has specific
   support for the mouse, it will act just like a standard two, or
   three button mouse.

   For the possible usage of wheels in the X Window environment,
   refer to that section.

   4.4.4. How do I use my delete key in sh and csh?

   For the Bourne Shell, add the following lines to your .shrc. See
   sh(1) and 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 your .cshrc. See
   csh(1).

 bindkey ^? delete-char # for console
 bindkey ^[[3~ delete-char # for xterm

   For more information, see this page.

     --------------------------------------------------------------

4.5 Other Hardware

   4.5.1. Workarounds for no sound from my pcm(4) sound card?

   4.5.2. Does FreeBSD support power management on my laptop?

   4.5.1. Workarounds for no sound from my 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:

 # mixer pcm 100 vol 100 cd 100

   4.5.2. Does FreeBSD support power management on my laptop?

   FreeBSD supports the ACPI features found in modern hardware.
   Further information can be found in acpi(4).

     --------------------------------------------------------------

                       Chapter 5 Troubleshooting

   5.1. Why is FreeBSD finding the wrong amount of memory on i386
   hardware?

   5.2. Why do my programs occasionally die with "Signal 11" errors?

   5.3. 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?

   5.4. Why do I get the error "maxproc limit exceeded by uid %i,
   please see tuning(7) and login.conf(5)"?

   5.5. Why does sendmail give me an error reading "mail loops back
   to myself"?

   5.6. Why do full screen applications on remote machines misbehave?

   5.7. Why does it take so long to connect to my computer via ssh or
   telnet?

   5.8. Why does "file: table is full" show up repeatedly in
   dmesg(8)?

   5.9. Why does the clock on my computer keep incorrect time?

   5.10. What does the error "swap_pager: indefinite wait buffer:"
   mean?

   5.11. What is a "lock order reversal"?

   5.12. What does "Called ... with the following non-sleepable locks
   held" mean?

   5.13. Why does buildworld/installworld die with the message
   "touch: not found"?

   5.1. Why is FreeBSD 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 can not be accessed by that address space.

   What happens to the memory that should appear in that location is
   dependent on your hardware. 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
   if you watch the boot messages.

   On a 32-bit version of FreeBSD, the memory appears lost, since it
   will be remapped above 4 GB, which a 32-bit kernel is unable to
   access. In this case, the solution is to build a PAE enabled
   kernel. See the entry on memory limits and about different memory
   limits on different platforms for more information.

   On a 64-bit version of FreeBSD, or when running a PAE-enabled
   kernel, FreeBSD will correctly detect and remap the memory so it
   is usable. During boot, however, it may seem as if FreeBSD is
   detecting more memory than the system really has, due to the
   described remapping. This is normal and the available memory will
   be corrected as the boot process completes.

   5.2. Why do my programs occasionally die with "Signal 11" errors?

   Signal 11 errors are caused when your 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 then you need to start investigating things very
   carefully.

   These problems can usually be attributed to either:

    1. If the problem is occurring only in a specific application
       that you are developing yourself it is probably a bug in your
       code.

    2. If it is a problem with part of the base FreeBSD system, it
       may also be buggy code, but more often than not these problems
       are found and fixed long before us general FAQ readers get to
       use these bits of code (that is what -current is for).

   In particular, a dead giveaway that this is not a FreeBSD bug is
   if you see the problem when you are compiling a program, but the
   activity that the compiler is carrying out changes each time.

   For example, suppose you are running make buildworld, and the
   compile fails while trying to compile ls.c into ls.o. If you then
   run make buildworld again, and the compile fails in the same place
   then this is a broken build - try updating your sources and try
   again. If the compile fails elsewhere then this is almost
   certainly hardware.

   What you should do:

   In the first case you can use a debugger e.g., gdb(1) to find the
   point in the program which is attempting to access a bogus address
   and then fix it.

   In the second case you need to verify that it is not your hardware
   at fault.

   Common causes of this include:

    1. Your hard disks might be overheating: Check the fans in your
       case are still working, as your disk (and perhaps other
       hardware might be overheating).

    2. 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 you need to ensure
       that you have hardware running at what it is specified to run
       at, at least while trying to solve this problem (in other
       words, clock it back to the default settings.)

       If you are overclocking then note that it is far cheaper to
       have a slow system than a fried system that needs replacing!
       Also the wider community is not often sympathetic to problems
       on overclocked systems, whether you believe it is safe or not.

    3. Dodgy memory: If you have multiple memory SIMMS/DIMMS
       installed then pull them all out and try running the machine
       with each SIMM or DIMM individually and narrow the problem
       down to either the problematic DIMM/SIMM or perhaps even a
       combination.

    4. Over-optimistic Motherboard settings: In your BIOS settings,
       and some motherboard jumpers you have options to set various
       timings, mostly the defaults will be sufficient, but
       sometimes, setting the wait states on RAM too low, or setting
       the "RAM Speed: Turbo" option, or similar in the BIOS will
       cause strange behavior. A possible idea is to set to BIOS
       defaults, but it might be worth noting down your settings
       first!

    5. Unclean or insufficient power to the motherboard. If you have
       any unused I/O boards, hard disks, or CD-ROMs in your system,
       try temporarily removing them or disconnecting the power cable
       from them, to see if your power supply can manage a smaller
       load. Or try another power supply, preferably one with a
       little more power (for instance, if your current power supply
       is rated at 250 Watts try one rated at 300 Watts).

   You should also read the SIG11 FAQ (listed below) which has
   excellent explanations of all these problems, albeit from a
   Linux(R) viewpoint. It also discusses how memory testing software
   or hardware can still pass faulty memory.

   Finally, if none of this has helped it is possible that you have
   just found a bug in FreeBSD, and you should follow the
   instructions to send a problem report.

   There is an extensive FAQ on this at the SIG11 problem FAQ.

   5.3. My system crashes with either "Fatal trap 12: page fault in
   kernel mode", or "panic:", and spits out a bunch of information.
   What should I do?

   The FreeBSD developers are very interested in these errors, but
   need some more information than just the error you see. Copy your
   full crash message. Then consult the FAQ section on kernel panics,
   build a debugging kernel, and get a backtrace. This might sound
   difficult, but you do not need any programming skills; you just
   have to follow the instructions.

   5.4. Why do I get the error "maxproc limit exceeded by uid %i,
   please see tuning(7) and login.conf(5)"?

   The FreeBSD kernel will only allow a certain number of processes
   to exist at one time. The number is based on the kern.maxusers
   sysctl(8) variable. kern.maxusers also affects various other
   in-kernel limits, such as network buffers. If your machine is
   heavily loaded, you probably want to increase kern.maxusers. This
   will increase these other system limits in addition to the maximum
   number of processes.

   To adjust your 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 your machine is lightly loaded, and you are simply running a
   very large number of processes, you can adjust this with the
   kern.maxproc tunable. If this tunable needs adjustment it needs to
   be defined in /boot/loader.conf. The tunable will not get adjusted
   until the system is rebooted. For more information about tuning
   tunables, see loader.conf(5). If these processes are being run by
   a single user, you will also need to adjust kern.maxprocperuid to
   be one less than your new kern.maxproc value. (It must be at least
   one less because one system program, init(8), must always be
   running.)

   5.5. Why does sendmail give me an error reading "mail loops back
   to myself"?

   You can find a detailed answer for this question in the Handbook.

   5.6. Why do full screen applications on remote machines misbehave?

   The remote machine may be setting your terminal type to something
   other than the cons25 terminal type required by the FreeBSD
   console.

   There are a number of possible work-arounds for this problem:

     * After logging on to the remote machine, set your TERM shell
       variable to ansi or sco if the remote machine knows about
       these terminal types.

     * Use a VT100 emulator like screen at the FreeBSD console.
       screen offers you the ability to run multiple concurrent
       sessions from one terminal, and is a neat program in its own
       right. Each screen window behaves like a VT100 terminal, so
       the TERM variable at the remote end should be set to vt100.

     * Install the cons25 terminal database entry on the remote
       machine. The way to do this depends on the operating system on
       the remote machine. The system administration manuals for the
       remote system should be able to help you here.

     * Fire up an X server at the FreeBSD end and login to the remote
       machine using an X based terminal emulator such as xterm or
       rxvt. The TERM variable at the remote host should be set to
       xterm or vt100.

   5.7. 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 telnet(1)'s case, when a login prompt
   appears).

   The problem: more likely than not, the delay is caused by the
   server software trying to resolve the client's IP address into a
   hostname. Many servers, including the Telnet and SSH servers that
   come with FreeBSD, do this to store the hostname in a log file for
   future reference by the administrator.

   The remedy: if the problem occurs whenever you connect from your
   computer (the client) to any server, the problem is with the
   client; likewise, if the problem only occurs when someone connects
   to your computer (the server) 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; conversely, if this
   is on the global Internet, you will most likely need to contact
   your ISP and ask them to fix it for you.

   If the problem is with the server, and this is on a local network,
   you need to configure the server to be able to resolve
   address-to-hostname queries for your local address range. See the
   hosts(5) and named(8) manual pages for more information. If this
   is on the global Internet, the problem may be that your server's
   resolver is not functioning correctly. To check, try to look up
   another host - say, www.yahoo.com. If it does not work, that is
   your problem.

   Following a fresh install of FreeBSD, 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, you will either need to fill in the
   missing information in /etc/resolv.conf or set UseDNS to no in
   sshd_config as a temporary workaround.

   5.8. Why does "file: table is full" show up repeatedly in
   dmesg(8)?

   This error message indicates you have exhausted the number of
   available file descriptors on your system. Please see the
   kern.maxfiles section of the Tuning Kernel Limits section of the
   Handbook for a discussion and solution.

   5.9. Why does the clock on my computer keep incorrect time?

   Your computer has two or more clocks, and FreeBSD has chosen to
   use the wrong one.

   Run dmesg(8), and check for lines that contain Timecounter. The
   one with the highest quality value that FreeBSD chose.

 # 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

   You can confirm this by checking the kern.timecounter.hardware
   sysctl(3).

 # 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 FreeBSD is unaware of these adjustments,
   and appears to gain or lose time.

   In this example, the i8254 clock is also available, and can be
   selected by writing its name to the kern.timecounter.hardware
   sysctl(3).

 # sysctl kern.timecounter.hardware=i8254
 kern.timecounter.hardware: TSC -> i8254

   Your 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

   5.10. What does the error "swap_pager: indefinite wait buffer:"
   mean?

   This means that a process is trying to page memory to 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 actually bad, you will also see disk errors in
   /var/log/messages and in the output of dmesg. Otherwise, check
   your cables and connections.

   5.11. What is a "lock order reversal"?

   The FreeBSD kernel uses a number of resource locks to arbitrate
   contention for certain resources. When multiple kernel threads try
   to obtain multiple resource locks, there's always the potential
   for a deadlock, where two threads have each obtained one of the
   locks and blocks forever waiting for the other thread to release
   one of the other locks. This sort of locking problem can be
   avoided if all threads obtain the locks in the same order.

   A run-time lock diagnostic system called witness(4), enabled in
   FreeBSD-CURRENT and disabled by default for stable branches and
   releases, detects the potential for deadlocks due to locking
   errors, including errors caused by obtaining multiple resource
   locks with a different order from different parts of the kernel.
   The 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 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 of
   the form "if you were unlucky, a deadlock would have happened
   here".

     Note: Problematic LORs tend to get fixed quickly, so check
     http://lists.FreeBSD.org/mailman/listinfo/freebsd-current before
     posting to the mailing lists.

   5.12. What does "Called ... with the following non-sleepable locks
   held" mean?

   This means that a function that may sleep was called while a mutex
   (or other unsleepable) lock was held.

   The reason this is an error is because mutexes are not intended to
   be held for long periods of time; they are supposed to only be
   held to maintain short periods of synchronization. This
   programming contract allows device drivers to use mutexes to
   synchronize with the rest of the kernel during interrupts.
   Interrupts (under FreeBSD) may not sleep. Hence it is imperative
   that no subsystem in the kernel block for an extended period while
   holding a mutex.

   To catch such errors, assertions may be added to the kernel that
   interact with the witness(4) subsystem to emit a warning or fatal
   error (depending on the system configuration) when a potentially
   blocking call is made while holding a mutex.

   In summary, such warnings are non-fatal, however with unfortunate
   timing they could cause undesirable effects ranging from a minor
   blip in the system's responsiveness to a complete system lockup.

   For additional information about locking in FreeBSD see
   locking(9).

   5.13. Why does buildworld/installworld die with the message
   "touch: not found"?

   This error does not mean that the touch(1) utility is missing. The
   error is instead probably due to the dates of the files being set
   sometime in the future. If your CMOS-clock is set to local time
   you need to run the command adjkerntz -i to adjust the kernel
   clock when booting into single user mode.

     --------------------------------------------------------------

                      Chapter 6 User Applications

   6.1. So, where are all the user applications?

   6.2. How do I download the Ports tree? Should I be using SVN?

   6.3. Does FreeBSD support Java(TM)?

   6.4. Why can I not build this port on my 8.X -, or 9.X -STABLE
   machine?

   6.5. I just tried to build INDEX using make index, and it failed.
   Why?

   6.6. I updated the sources, now how do I update my installed
   ports?

   6.7. Do I need to recompile every port each time I perform a major
   version update?

   6.8. Do I need to recompile every port each time I perform a minor
   version update?

   6.9. Why is /bin/sh so minimal? Why does FreeBSD not use bash or
   another shell?

   6.10. How do I create audio CDs from my MIDI files?

   6.11. Where can I get an Office Suite for FreeBSD?

   6.12. Are there any Database systems for FreeBSD?

   6.13. How can I convert from pkgng to the old package tools?

   6.1. So, where are all the user applications?

   Please take a look at the ports page for info on software packages
   ported to FreeBSD. The list currently tops 24,000 and is growing
   daily, so come back to check often or subscribe to the FreeBSD
   announcements mailing list for periodic updates on new entries.

   Most ports should work on the 8.X, and 9.X branches. Each time a
   FreeBSD release is made, a snapshot of the ports tree at the time
   of release in also included in the ports/ directory.

   We also support the concept of a "package", essentially no more
   than a compressed binary distribution with a little extra
   intelligence embedded in it for doing whatever custom installation
   work is required. A package can be installed and uninstalled again
   easily without having to know the gory details of which files it
   includes.

   Use pkg_add(1) on the specific package files you are interested in
   installing. Package files can usually be identified by their .tbz
   suffix and CD-ROM distribution people will have a packages/All
   directory on their CD which contains such files. They can also be
   downloaded over the net for various versions of FreeBSD at the
   following locations:

   for 8.X -RELEASE/8-STABLE

           ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-8-stable

   for 9.X -RELEASE/9-STABLE

           ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-9-stable

   or your nearest local mirror site.

   Note that all ports may not be available as packages since new
   ones are constantly being added. It is always a good idea to check
   back periodically to see which packages are available at the
   ftp.FreeBSD.org master site.

   6.2. 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.

     * Use SVN directly if you need custom patches to the ports tree.

     * Use CTM if you prefer getting patches by email (this is a
       rarer use case).

   Any other method should be considered a legacy method. If you do
   not already use them, do not start.

   6.3. Does FreeBSD support Java(TM)?

   Yes. Please see http://www.FreeBSD.org/java/.

   6.4. Why can I not build this port on my 8.X -, or 9.X -STABLE
   machine?

   If you are running a FreeBSD version that lags significantly
   behind -CURRENT or -STABLE, you may need to update your Ports
   Collection; see the Keeping Up section of the Porter's Handbook
   for further information on how to do this. If you are up to date,
   then someone might have committed a change to the port which works
   for -CURRENT but which broke the port for -STABLE. Please submit a
   bug report on this with the send-pr(1) command, since the Ports
   Collection is supposed to work for both the -CURRENT and -STABLE
   branches.

   6.5. I just tried to build INDEX using make index, and it failed.
   Why?

   First, always make sure that you have a complete up-to-date Ports
   Collection. 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, please try to make INDEX with
   those make variables turned off before reporting it to FreeBSD
   ports mailing list.

   6.6. I updated the sources, now how do I update my installed
   ports?

   FreeBSD does not include a port upgrading tool, but it does have
   some tools to make the upgrade process somewhat easier. You can
   also install additional tools to simplify port handling, see the
   Upgrading Ports section in the FreeBSD Handbook.

   6.7. Do I need to recompile every port each time I perform a major
   version update?

   By all means! While a recent system will run with software
   compiled under an older release, you will end up with things
   randomly crashing and failing to work once you start installing
   other ports or updating a portion of what you already have.

   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 FreeBSD
   Handbook.

   6.8. Do I need to recompile every port each time I perform a minor
   version update?

   In general, no. FreeBSD developers do their utmost to guarantee
   binary compatibility across all releases with the same major
   version number. Any exceptions will be documented in the Release
   Notes, and advice given there should be followed.

   6.9. Why is /bin/sh so minimal? Why does FreeBSD not use bash or
   another shell?

   Many people need to write shell scripts which will be portable
   across many systems. That is why POSIX(R) specifies the shell and
   utility commands in great detail. Most scripts are written in
   Bourne shell (sh(1)), and because several important programming
   interfaces (make(1), system(3), 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, tcsh(1), and zsh are available. (You can compare for
   yourself the memory utilization of all these shells by looking at
   the "VSZ" and "RSS" columns in a ps -u listing.)

   6.10. 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:

 % 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 FreeBSD Handbook.

   6.11. Where can I get an Office Suite for FreeBSD?

   The open-source Apache OpenOffice and LibreOffice office suites
   work natively on FreeBSD.

   FreeBSD also includes a variety of text editors, spreadsheets, and
   drawing programs in the Ports Collection.

   6.12. Are there any Database systems for FreeBSD?

   Yes! See the Commercial Vendors section of FreeBSD's Web site.

   Also see the Databases section of the Ports Collection.

   6.13. How can I convert from pkgng to the old package tools?

   Short answer: it is not possible.

   Longer answer: if you have made any changes using pkg converting
   back is non-trivial and requires lots of manual editing of
   internal package database files. However, if you have just run
   pkg2ng then you may remove /var/db/pkg/local.sqlite and extract
   /var/backups/pkgdb.bak.tbz.

     --------------------------------------------------------------

                     Chapter 7 Kernel Configuration

   7.1. I would like to customize my kernel. Is it difficult?

   7.2. Why is my kernel so big?

   7.3. Why does every kernel I try to build fail to compile, even
   GENERIC?

   7.4. How can I verify which scheduler is in use on a running
   system?

   7.5. What is kern.sched.quantum?

   7.1. I would like to customize my kernel. Is it difficult?

   Not at all! Check out the kernel config section of the Handbook.

     Note: 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, so if
     you make a mistake the next time you play with your
     configuration you can boot the previous version of your kernel.

   7.2. Why is my kernel so big?

   GENERIC kernels shipped with FreeBSD and later are compiled in
   debug mode. Kernels built in debug mode contain many symbols in
   separate files that are used for debugging, thus greatly
   increasing the size of /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.

   However, if you are running low on disk space, there are different
   options to reduce the size of /boot/kernel/.

   If you do not want the symbol files to be installed, make sure you
   have the following line present in /etc/src.conf:

 WITHOUT_KERNEL_SYMBOLS=yes

   For more information see src.conf(5).

   If you do not want to build a debug kernel, make sure that both of
   the following are true:

     * You do not have a line in your kernel configuration file that
       reads:

 makeoptions DEBUG=-g

     * You are not running config(8) with -g.

   Either of the above settings will cause your kernel to be built in
   debug mode. As long as you make sure you follow the steps above,
   you can build your kernel normally.

   If you want only the modules you use to be built and installed,
   make sure you have a line like below in /etc/make.conf:

 MODULES_OVERRIDE= accf_http ipfw

   Replace accf_httpd ipfw with a list of modules you need. Only
   these modules will be built. This does not only reduce the size of
   the kernel directory but also decreases the amount of time needed
   to build your kernel. For more information see
   /usr/share/examples/etc/make.conf.

   You can also remove unneeded devices from your kernel to further
   reduce the size. See Q: 7.1. for more information.

   To put any of these options into effect you will have to build and
   install your new kernel.

   Most kernels (/boot/kernel/kernel) tend to be around 12 MB to
   16 MB.

   7.3. Why does every kernel I try to build fail to compile, even
   GENERIC?

   There are a number of possible causes for this problem. They are,
   in no particular order:

     * You are not using the make buildkernel and make installkernel
       targets, and your source tree is different from the one used
       to build the currently running system (e.g., you are compiling
       9.1-RELEASE on a 8.4-RELEASE system). If you are attempting an
       upgrade, please read /usr/src/UPDATING, paying particular
       attention to the "COMMON ITEMS" section at the end.

     * You are using the make buildkernel and make installkernel
       targets, but you failed to assert the completion of the make
       buildworld target. The make buildkernel target relies on files
       generated by the make buildworld target to complete its job
       correctly.

     * Even if you are trying to build FreeBSD-STABLE, it is possible
       that you fetched the source tree at a time when it was either
       being modified, or broken for other reasons; only releases are
       absolutely guaranteed to be buildable, although FreeBSD-STABLE
       builds fine the majority of the time. If you have not already
       done so, try re-fetching the source tree and see if the
       problem goes away. Try using a different server in case the
       one you are using is having problems.

   7.4. How can I verify 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:

 % sysctl kern.sched.name
 kern.sched.name: ULE

   7.5. 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.

     --------------------------------------------------------------

            Chapter 8 Disks, File Systems, and Boot Loaders

   8.1. How can I add my new hard disk to my FreeBSD system?

   8.2. How do I move my system over to my huge new disk?

   8.3. Which partitions can safely use Soft Updates? I have heard
   that Soft Updates on / can cause problems. What about Journaled
   Soft Updates?

   8.4. Can I mount other foreign file systems under FreeBSD?

   8.5. How do I mount a secondary DOS partition?

   8.6. Is there a cryptographic file system for FreeBSD?

   8.7. How can I use the Windows NT(R) loader to boot FreeBSD?

   8.8. How do I boot FreeBSD and Linux from LILO?

   8.9. How do I boot FreeBSD and Linux using GRUB?

   8.10. How do I boot FreeBSD and Linux using BootEasy?

   8.11. How do I change the boot prompt from ??? to something more
   meaningful?

   8.12. I have a new removable drive, how do I use it?

   8.13. Why do I get "Incorrect super block" when mounting a CD-ROM?

   8.14. Why do I get "Device not configured" when mounting a CD-ROM?

   8.15. Why do all non-English characters in filenames show up as
   "?" on my CDs when mounted in FreeBSD?

   8.16. I burned a CD under FreeBSD and now I can not read it under
   any other operating system. Why?

   8.17. How can I create an image of a data CD?

   8.18. Why can I not mount an audio CD?

   8.19. How do I mount a multi-session CD?

   8.20. How do I let ordinary users mount CD-ROMs, DVDs, USB drives,
   and other removable media?

   8.21. The du and df commands show different amounts of disk space
   available. What is going on?

   8.22. How can I add more swap space?

   8.23. Why does FreeBSD see my disk as smaller than the
   manufacturer says it is?

   8.24. How is it possible for a partition to be more than 100%
   full?

   8.1. How can I add my new hard disk to my FreeBSD system?

   See the Adding Disks section in the FreeBSD Handbook.

   8.2. How do I move my system over to my huge new disk?

   The best way is to reinstall the OS on the new disk, then move the
   user data over. This is highly recommended if you have been
   tracking -STABLE for more than one release, or have updated a
   release instead of installing a new one. You can install booteasy
   on both disks with boot0cfg(8), and dual boot them 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
   sade(8) or gpart(8). If the disks are MBR-formatted, you can also
   install booteasy on both disks with boot0cfg(8), so that you can
   dual boot to the old or new system after the copying is done.

   Now you have the new disk set up, and are ready to move the data.
   Unfortunately, you cannot just blindly copy the data. Things like
   device files (in /dev), flags, and links tend to screw that up.
   You need to use tools that understand these things, which means
   dump(8). Although it is suggested that you move the data in single
   user mode, it is not required.

   You should never use anything but dump(8) and restore(8) to move
   the root file system. The tar(1) command may work - then again, it
   may not. You should also use dump(8) and restore(8) if you are
   moving a single partition to another empty partition. The sequence
   of steps to use dump to move a partitions data to a new partition
   is:

    1. newfs the new partition.

    2. mount it on a temporary mount point.

    3. cd to that directory.

    4. dump the old partition, piping output to the new one.

   For example, if you are going to move root to /dev/ada1s1a, with
   /mnt as the temporary mount point, it is:

 # newfs /dev/ada1s1a
 # mount /dev/ada1s1a /mnt
 # cd /mnt
 # dump 0af - / | restore rf -

   Rearranging your 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:

 # newfs /dev/ada1s1a
 # mount /dev/ada1s1a /mnt
 # cd /mnt
 # dump 0af - / | restore rf -
 # cd var
 # dump 0af - /var | restore rf -

   To split a directory from its parent, say putting /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:

 # newfs /dev/ada1s1a
 # newfs /dev/ada1s1d
 # mount /dev/ada1s1a /mnt
 # mkdir /mnt/var
 # mount /dev/ada1s1d /mnt/var
 # cd /mnt
 # dump 0af - / | restore rf -

   You might prefer cpio(1), pax(1), tar(1) to dump(8) for user data.
   At the time of this writing, these are known to lose file flag
   information, so use them with caution.

   8.3. Which partitions can safely use Soft Updates? I have heard
   that Soft Updates on / can cause problems. What about Journaled
   Soft Updates?

   Short answer: you can usually use Soft Updates safely on all
   partitions.

   Long answer: Soft Updates has two characteristics that may be
   undesirable on certain paritions. First, a Soft Updates partition
   has a small chance of losing data during a system crash. (The
   partition will not be corrupted; 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 you delete one large file and immediately
   create another large file. 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. You get an error that
   the partition does not have enough space, although you know
   perfectly well that you just released a large chunk of space! When
   you try again mere seconds later, the file creation works as you
   expect. This has left more than one user scratching his head and
   doubting his sanity, the FreeBSD file system, or both.

   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 you should be aware that
   it exists. If your system cannot tolerate this much risk, do not
   use Soft Updates on the root file system!

   / is traditionally one of the smallest partitions. If you put the
   /tmp directory on / and you have a busy /tmp, you might see
   intermittent space problems. Symlinking /tmp to /var/tmp will
   solve this problem.

   Finally, dump(8) does not work in live mode (-L) on a filesystem,
   with Journaled Soft Updates (SU+J).

   8.4. Can I mount other foreign file systems under FreeBSD?

   FreeBSD supports a variety of other file systems.

   UFS

           UFS CD-ROMs can be mounted directly on FreeBSD. Mounting
           disk partitions from Digital UNIX and other systems that
           support UFS may be more complex, depending on the details
           of the disk partitioning for the operating system in
           question.

   ext2/ext3

           FreeBSD supports ext2fs and ext3fs partitions. See
           mount_ext2fs(8) for more information.

   NTFS

           FUSE based NTFS support is available as a port
           (sysutils/fusefs-ntfs). For more information see ntfs-3g.

   FAT

           FreeBSD includes a read-write FAT driver. For more
           information, see mount_msdosfs(8).

   ZFS

           FreeBSD includes a port of Sun(TM)'s ZFS driver. The
           current recommendation is to use it only on amd64
           platforms with sufficient memory. For more information,
           see zfs(8).

   FreeBSD also supports network file systems such as NFS (see
   mount_nfs(8)), NetWare (see mount_nwfs(8)), and Microsoft-style
   SMB file systems (see mount_smbfs(8)). You can find ports based on
   FUSE (sysutils/fusefs-kmod) for many other file systems.

   8.5. How do I mount a secondary DOS partition?

   The secondary DOS partitions are found after all the primary
   partitions. For example, if you have an "E" partition as the
   second DOS partition on the second SCSI drive, there will be a
   device file for "slice 5" in /dev, so simply mount it:

 # mount -t msdosfs /dev/da1s5 /dos/e

   8.6. Is there a cryptographic file system for FreeBSD?

   Yes. You can use either gbde(8) or geli(8), see the Encrypting
   Disk Partitions section of the FreeBSD Handbook.

   8.7. How can I use the Windows NT(R) loader to boot FreeBSD?

   The general idea is that you copy the first sector of your native
   root FreeBSD partition into a file in the DOS/Windows NT
   partition. Assuming you name that file something like
   c:\bootsect.bsd (inspired by c:\bootsect.dos), you can then edit
   c:\boot.ini to come up with something like this:

 [boot loader]
 timeout=30
 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
 [operating systems]
 multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows NT"
 C:\BOOTSECT.BSD="FreeBSD"
 C:\="DOS"

   If FreeBSD is installed on the same disk as the Windows NT boot
   partition simply copy /boot/boot1 to C:\BOOTSECT.BSD. However, if
   FreeBSD is installed on a different disk /boot/boot1 will not
   work, /boot/boot0 is needed.

   /boot/boot0 needs to be installed using sysinstall(8) by selecting
   the FreeBSD boot manager on the screen which asks if you wish to
   use a boot manager. This is because /boot/boot0 has the partition
   table area filled with NULL characters but sysinstall(8) copies
   the partition table before copying /boot/boot0 to the MBR.

     Warning: Do not simply copy /boot/boot0 instead of /boot/boot1;
     you will overwrite your partition table and render your computer
     un-bootable!

   When the FreeBSD boot manager runs it records the last OS booted
   by setting the active flag on the partition table entry for that
   OS and then writes the whole 512-bytes of itself back to the MBR
   so if you just copy /boot/boot0 to C:\BOOTSECT.BSD then it writes
   an empty partition table, with the active flag set on one entry,
   to the MBR.

   8.8. How do I boot FreeBSD and Linux from LILO?

   If you have FreeBSD and Linux on the same disk, just follow LILO's
   installation instructions for booting a non-Linux operating
   system. Very briefly, these are:

   Boot Linux, and add the following lines to /etc/lilo.conf:

 other=/dev/hda2
         table=/dev/hda
         label=FreeBSD

   (the above assumes that your FreeBSD slice is known to Linux as
   /dev/hda2; tailor to suit your setup). Then, run lilo as root and
   you should be done.

   If FreeBSD resides on another disk, you need to add
   loader=/boot/chain.b to the LILO entry. For example:

 other=/dev/dab4
         table=/dev/dab
         loader=/boot/chain.b
         label=FreeBSD

   In some cases you may need to specify the BIOS drive number to the
   FreeBSD boot loader to successfully boot off the second disk. For
   example, if your FreeBSD SCSI disk is probed by BIOS as BIOS disk
   1, at the FreeBSD boot loader prompt you need to specify:

 Boot: 1:da(0,a)/boot/kernel/kernel

   You can configure boot(8) to automatically do this for you at boot
   time.

   The Linux+FreeBSD mini-HOWTO is a good reference for FreeBSD and
   Linux interoperability issues.

   8.9. How do I boot FreeBSD and Linux using GRUB?

   Booting FreeBSD using GRUB is very simple. Just add the following
   to your configuration file /boot/grub/menu.lst (or
   /boot/grub/grub.conf in some systems, e.g., Red Hat Linux and its
   derivatives).

 title FreeBSD 6.1
         root (hd0,a)
         kernel /boot/loader

   Where hd0,a points to your root partition on the first disk. If
   you need to specify which slice number should be used, use
   something like this (hd0,2,a). By default, if the slice number is
   omitted, GRUB searches the first slice which has a partition.

   8.10. How do I boot FreeBSD and Linux using BootEasy?

   Install LILO at the start of your Linux boot partition instead of
   in the Master Boot Record. You can then boot LILO from BootEasy.

   If you are running Windows and Linux this is recommended anyway,
   to make it simpler to get Linux booting again if you should need
   to reinstall Windows (which is a Jealous Operating System, and
   will bear no other Operating Systems in the Master Boot Record).

   8.11. How do I change the boot prompt from ??? to something more
   meaningful?

   You can not do that with the standard boot manager without
   rewriting it. There are a number of other boot managers in the
   sysutils ports category that provide this functionality.

   8.12. I have a new removable drive, how do I use it?

   If the drive already has a file system on it, you can use a
   command like this:

 # mount -t msdosfs /dev/da0s1 /mnt

   If the drive will only be used with FreeBSD systems it is better
   idea to stick a BSD file system on it, like UFS or ZFS. You will
   get long filename support, at least a 2X improvement in
   performance, and a lot more stability. If the drive will be used
   by other operating systems a more portable choice, such as
   msdosfs, is better.

 # dd if=/dev/zero of=/dev/da0 count=2
 # gpart create -s GPT /dev/da0
 # gpart add -t freebsd-ufs /dev/da0

   Finally, create a new file system:

 # newfs /dev/da0p1

   and mount it:

 # mount /dev/da0s1 /mnt

   It is a good idea to add a line to /etc/fstab (see fstab(5)) so
   you can just type mount /mnt in the future:

 /dev/da0p1 /mnt ufs rw,noauto 0 0

   8.13. Why do I get "Incorrect super block" when mounting a CD-ROM?

   You have to tell mount(8) the type of the device that you want to
   mount. This is described in the Handbook section on optical media,
   specifically the section Using Data CDs.

   8.14. Why do I get "Device not configured" when mounting a CD-ROM?

   This generally means that there is no CD-ROM in the CD-ROM drive,
   or the drive is not visible on the bus. Please see the Using Data
   CDs section of the Handbook for a detailed discussion of this
   issue.

   8.15. Why do all non-English characters in filenames show up as
   "?" on my CDs when mounted in FreeBSD?

   Your CD-ROM probably uses the "Joliet" extension for storing
   information about files and directories. This is discussed in the
   Handbook chapter on creating and using CD-ROMs, specifically the
   section on Using Data CD-ROMs.

   8.16. I burned a CD under FreeBSD and now I can not read it under
   any other operating system. Why?

   You most likely burned a raw file to your CD, rather than creating
   an ISO 9660 file system. Take a look at the Handbook chapter on
   creating CD-ROMs, particularly the section on burning raw data
   CDs.

   8.17. How can I create an image of a data CD?

   This is discussed in the Handbook section on duplicating data CDs.
   For more on working with CD-ROMs, see the Creating CDs Section in
   the Storage chapter in the Handbook.

   8.18. Why can I not mount an audio CD?

   If you try to mount an audio CD, you will get an error like
   "cd9660: /dev/acd0c: Invalid argument". This is because mount only
   works on file systems. Audio CDs do not have file systems; they
   just have data. You need a program that reads audio CDs, such as
   the audio/xmcd port.

   8.19. How do I mount a multi-session CD?

   By default, mount(8) will attempt to mount the last data track
   (session) of a CD. If you would like to load an earlier session,
   you must use the -s command line argument. Please see
   mount_cd9660(8) for specific examples.

   8.20. 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.

 # 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/da00       0666

   All users can now mount devices they could read onto a directory
   that they own:

 % mkdir ~/my-mount-point
 % mount -t msdosfs /dev/da0~/my-mount-point

   Unmounting the device is simple:

 % umount ~/my-mount-point

   Enabling vfs.usermount, however, has negative security
   implications. A better way to access MS-DOS(R) formatted media is
   to use the emulators/mtools package in the Ports Collection.

     Note: The device name used in the previous examples must be
     changed according to your configuration.

   8.21. The du and df commands show different amounts of disk space
   available. What is going on?

   You need to understand what du and df really do. 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 you delete the file, 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. You can see this easily enough with a program
   such as more. Assume you have a file large enough that its
   presence affects the output of du and df. (Since disks can be so
   large today, this might be a very large file!) If you delete this
   file while using more on it, more does not immediately choke and
   complain that it cannot view the file. The entry is simply removed
   from the directory so no other program or user can access it. du
   shows that it is gone - 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 you end the
   more session, du and df will agree.

   This situation is common on web servers. Many people set up a
   FreeBSD web server and forget to rotate the log files. The access
   log fills up /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 newsyslog(8).

   Note that Soft Updates can delay the freeing of disk space; you
   might need to wait up to 30 seconds for the change to be visible!

   8.22. How can I add more swap space?

   In the Configuration and Tuning section of the Handbook, you will
   find a section describing how to do this.

   8.23. Why does FreeBSD see my disk as smaller than the
   manufacturer says it is?

   Disk manufacturers calculate gigabytes as a billion bytes each,
   whereas FreeBSD calculates them as 1,073,741,824 bytes each. This
   explains why, for example, FreeBSD's boot messages will report a
   disk that supposedly has 80 GB as holding 76,319 MB.

   Also note that FreeBSD will (by default) reserve 8% of the disk
   space.

   8.24. 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. df(1) does not
   count that space when calculating the Capacity column, so it can
   exceed 100%. Also, you will notice that the Blocks column is
   always greater than the sum of the Used and Avail columns, usually
   by a factor of 8%.

   For more details, look up -m in tunefs(8).

     --------------------------------------------------------------

8.1 ZFS

   8.1.1. What is the minimum amount of RAM one should have to run
   ZFS?

   8.1.2. What is the ZIL and when does it get used?

   8.1.3. Do I need a SSD for ZIL?

   8.1.4. What is the L2ARC?

   8.1.5. Is enabling deduplication advisable?

   8.1.6. I can not delete or create files on my ZFS pool. How can I
   fix this?

   8.1.7. Does ZFS support TRIM for Solid State Drives?

   8.1.1. 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.

   8.1.2. 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 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.

   8.1.3. Do I need a SSD for ZIL?

   By default, ZFS stores the ZIL in the pool with all the data. If
   your 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.

   8.1.4. What is the L2ARC?

   The L2ARC is a read cache stored on a fast device such as an SSD.
   This cache is not persisent 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.

   8.1.5. 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.

   8.1.6. I can not 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 a file you want to delete.

 % truncate -s 0 unimportant-file

   File truncation works because a new transaction is not started,
   new spare blocks are created instead.

     Note: On systems with additional ZFS dataset tuning, such as
     deduplication, the space may not be immediately available

   8.1.7. Does ZFS support TRIM for Solid State Drives?

   ZFS TRIM support was added to FreeBSD 10-CURRENT with revision
   r240868. ZFS TRIM support is not yet available on the -STABLE
   branches.

   ZFS TRIM is enabled by default, and can be turned off by adding
   this line to /etc/sysctl.conf:

 vfs.zfs.trim_disable=1

     Note: ZFS TRIM may not work with all configurations, such as a
     ZFS filesystem on a GELI-backed device.

     --------------------------------------------------------------

                    Chapter 9 System Administration

   9.1. Where are the system start-up configuration files?

   9.2. How do I add a user easily?

   9.3. Why do I keep getting messages like "root: not found" after
   editing /etc/crontab

   9.4. Why do I get the error, "you are not in the correct group to
   su root" when I try to su to root?

   9.5. 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?

   9.6. Why am I having trouble setting up my printer?

   9.7. How can I correct the keyboard mappings for my system?

   9.8. Why can I not get user quotas to work properly?

   9.9. Does FreeBSD support System V IPC primitives?

   9.10. What other mail-server software can I use instead of
   sendmail?

   9.11. I have forgotten the root password! What do I do?

   9.12. How do I keep Control+Alt+Delete from rebooting the system?

   9.13. How do I reformat DOS text files to UNIX ones?

   9.14. How do I kill processes by name?

   9.15. How do I re-read /etc/rc.conf and re-start /etc/rc without a
   reboot?

   9.16. I tried to update my system to the latest -STABLE, but got
   -BETAx, -RC or -PRERELEASE! What is going on?

   9.17. I tried to install a new kernel, and the chflags(1) failed.
   How do I get around this?

   9.18. I cannot change the time on my system by more than one
   second! How do I get around this?

   9.19. Why is rpc.statd using 256 MB of memory?

   9.20. Why can I not unset the schg file flag?

   9.21. Why does SSH authentication through .shosts not work by
   default in recent versions of FreeBSD?

   9.22. What is vnlru?

   9.23. What do the various memory states displayed by top mean?

   9.24. How much free memory is available?

   9.25. What is /var/empty? I can not delete it!

   9.26. I just changed /etc/newsyslog.conf. How can I check if it
   does what I expect?

   9.27. My time is wrong, how can I change the timezone?

   9.1. Where are the system start-up configuration files?

   The primary configuration file is /etc/defaults/rc.conf (see
   rc.conf(5)). System startup scripts such as /etc/rc and /etc/rc.d
   (see rc(8)) just include this file. Do not edit this file!
   Instead, if there is any entry in /etc/defaults/rc.conf that you
   want to change, you should copy the line into /etc/rc.conf and
   change it there.

   For example, if you wish to start named(8), the included DNS
   server, all you need to do is:

 # 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.

   9.2. How do I add a user easily?

   Use the adduser(8) command, or the pw(8) command for more
   complicated situations.

   To remove the user, use the rmuser(8) command or, if necessary,
   pw(8).

   9.3. Why do I keep getting messages like "root: not found" after
   editing /etc/crontab

   This is normally caused by editing the system crontab
   (/etc/crontab) and then using crontab(1) to install it:

 # crontab /etc/crontab

   This is not the correct way to do things. The system crontab has a
   different format to the per-user crontabs which crontab(1) updates
   (the crontab(5) manual page explains the differences in more
   detail).

   If this is what you did, the extra crontab is simply a copy of
   /etc/crontab in the wrong format it. Delete it with the command:

 # crontab -r

   Next time, when you edit /etc/crontab, you should not do anything
   to inform cron(8) of the changes, since it will notice them
   automatically.

   If you want something to be run once per day, week, or month, it
   is probably better to add shell scripts /usr/local/etc/periodic,
   and let the periodic(8) command run from the system cron schedule
   it with the other periodic system tasks.

   The actual reason for the error is that the system crontab has an
   extra field, specifying which user to run the command as. In the
   default system crontab provided with FreeBSD, this is root for all
   entries. When this crontab is used as the root user's crontab
   (which is not the same as the system crontab), cron(8) assumes the
   string root is the first word of the command to execute, but no
   such command exists.

   9.4. 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. To su to root (or any other account
   with superuser privileges), you must be in 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. With this feature, this is not
   strictly true; su(1) will prevent them from even trying to enter
   the password if they are not in wheel.

   To allow someone to su to root, simply put them in the wheel
   group. Use pw(8) for this purpose.

 # pw groupmod wheel -m lisa

   The above example will add user lisa to the group wheel.

   9.5. 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, simply 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 your
   favorite editor is on a network file system, you will need to
   either configure the network manually before you can mount network
   file systems, or use an editor which resides on a local file
   system, such as ed(1).

   If you intend to use a full screen editor such as vi(1) or
   emacs(1), you may also need to run export TERM=xterm on FreeBSD
   9.0+, or export TERM=cons25 on FreeBSD 8.X so that these editors
   can load the correct data from the termcap(5) database.

   Once you have performed these steps, you can edit /etc/rc.conf as
   you usually would to fix the syntax error. The error message
   displayed immediately after the kernel boot messages should tell
   you the number of the line in the file which is at fault.

   9.6. Why am I having trouble setting up my printer?

   See the Handbook entry on printing. It should cover most of your
   problem.

   Some printers require a host-based driver to do any kind of
   printing. These so-called "WinPrinters" are not natively supported
   by FreeBSD. If your printer does not work in DOS or Windows, it is
   probably a WinPrinter. Your only hope of getting one of these to
   work is to check if the print/pnm2ppa port supports it.

   9.7. How can I correct the keyboard mappings for my system?

   Please see the Handbook section on using localization,
   specifically the section on console setup.

   9.8. Why can I not get user quotas to work properly?

   * It is possible that your kernel is not configured to use quotas.
     If this is the case, you will need to add the following line to
     your kernel configuration file and recompile:

 options QUOTA

     Please read 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, i.e.:

             File System                      Quota file              
     /usr                         /usr/admin/quotas                   
     /home                        /home/admin/quotas                  
     ...                          ...                                 

   9.9. Does FreeBSD support System V IPC primitives?

   Yes, FreeBSD 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 your kernel config:

 options    SYSVSHM          # enable shared memory
 options    SYSVSEM          # enable for semaphores
 options    SYSVMSG          # enable for messaging

   Recompile and install your kernel.

   9.10. What other mail-server software can I use instead of
   sendmail?

   The sendmail server is the default mail-server software for
   FreeBSD, but you can easily replace it with one of the other MTA
   (for instance, an MTA installed from the ports).

   There are various alternative MTAs in the ports tree already, with
   mail/exim, mail/postfix, mail/qmail, and mail/zmailer being some
   of the most popular choices.

   Diversity is nice, and the fact that you have many different
   mail-servers to chose from is considered a good thing; therefore
   try to avoid asking questions like "Is sendmail better than
   qmail?" in the mailing lists. If you do feel like asking, first
   check the mailing list archives. The advantages and disadvantages
   of each and every one of the available MTAs have already been
   discussed a few times.

   9.11. 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. You will be dropped to a # prompt. Enter mount -urw /
   to remount your 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 exit(1) to continue booting.

     Note: If you are still prompted to give the root password when
     entering the Single User mode, it means that the console has
     been marked as insecure in /etc/ttys. In this case it will be
     required to boot from a FreeBSD installation disk, choose the
     Live CD or Shell at the beginning of the install process and
     issue the commands mentioned above. You will need to mount the
     specific partition in this case and then chroot to it, i.e.,
     replace mount -urw / by mount /dev/ada0p1 /mnt; chroot /mnt for
     a system on ada0p1.

     Note: If you cannot mount your root partition from Single User
     mode, it is possible that the partitions are encrypted and it is
     impossible to mount them without the access keys. Your chances
     depend on the chosen implementation. For more information see
     the section about encrypted disks in the FreeBSD Handbook.

   9.12. How do I keep Control+Alt+Delete from rebooting the system?

   If you are using syscons(4) (the default console driver) build and
   install a new kernel with the line in the configuration file:

 options SC_DISABLE_REBOOT

   This can also be done by setting the following sysctl(8) which
   does not require a reboot or kernel recompile:

 # sysctl hw.syscons.kbd_reboot=0

     Note: The above two methods are exclusive: The sysctl(8) does
     not exist if you compile your kernel with the SC_DISABLE_REBOOT
     option.

   9.13. How do I reformat DOS text files to UNIX ones?

   Use this perl(1) command:

 % 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 you can use the tr(1) command:

 % 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.

   9.14. How do I kill processes by name?

   Use pkill(1).

   9.15. 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.

   On the console do:

 # shutdown now
 (Note: without -r or -h)

 # return
 # exit

   9.16. I tried to update my system to the latest -STABLE, but got
   -BETAx, -RC or -PRERELEASE! What is going on?

   Short answer: it is just a name. RC stands for "Release
   Candidate". It signifies that a release is imminent. In FreeBSD,
   -PRERELEASE is typically synonymous with the code freeze before a
   release. (For some releases, the -BETA label was used in the same
   way as -PRERELEASE.)

   Long answer: FreeBSD derives its releases from one of two places.
   Major, dot-zero, releases, such as 9.0-RELEASE are branched from
   the head of the development stream, commonly referred to as
   -CURRENT. 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.

   9.17. I tried to install a new kernel, and the chflags(1) failed.
   How do I get around this?

   Short answer: You are probably at security level greater than 0.
   Reboot directly to Single User mode to install the kernel.

   Long answer: FreeBSD disallows changing system flags at security
   levels greater than 0. You can check your security level with the
   command:

 # sysctl kern.securelevel

   You cannot lower the security level; you have to boot to Single
   Mode to install the kernel, or change the security level in
   /etc/rc.conf then reboot. See the init(8) manual page for details
   on securelevel, and see /etc/defaults/rc.conf and the rc.conf(5)
   manual page for more information on rc.conf.

   9.18. I cannot change the time on my system by more than one
   second! How do I get around this?

   Short answer: You are probably at security level greater than 1.
   Reboot directly to Single User mode to change the date.

   Long answer: FreeBSD disallows changing the time by more that one
   second at security levels greater than 1. You can check your
   security level with the command:

 # sysctl kern.securelevel

   You cannot lower the security level; you have to boot to Single
   User mode to change the date, or change the security level in
   /etc/rc.conf then reboot. See the init(8) manual page for details
   on securelevel, and see /etc/defaults/rc.conf and the rc.conf(5)
   manual page for more information on rc.conf.

   9.19. 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 top(1) and
   ps(1).

   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 mmap(2) is 0x10000000, or one sixteenth of the address
   space on an IA32, or exactly 256 MB.

   9.20. Why can I not unset the schg file flag?

   You are running at an elevated (i.e., greater than 0) securelevel.
   Lower the securelevel and try again. For more information, see the
   FAQ entry on securelevel and the init(8) manual page.

   9.21. Why does SSH authentication through .shosts not work by
   default in recent versions of FreeBSD?

   The reason why .shosts authentication does not work by default in
   more recent versions of FreeBSD is because ssh(1) is not installed
   suid root by default. To "fix" this, you can do one of the
   following:

     * As a permanent fix, set ENABLE_SUID_SSH to true in
       /etc/make.conf then rebuild and reinstall ssh(1).

     * As a temporary fix, change the mode on /usr/bin/ssh to 4555 by
       running chmod 4555 /usr/bin/ssh as root.

   9.22. 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 if you have a huge amount of RAM and are accessing
   tens of thousands of tiny files.

   9.23. 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.

   9.24. 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.

   9.25. What is /var/empty? I can not delete it!

   /var/empty is a directory that the sshd(8) program uses when
   performing privilege separation. The /var/empty directory is
   empty, owned by root and has the schg flag set.

   Although it is not recommended to delete this directory, to do so
   you will need to unset the schg flag first. See the chflags(1)
   manual page for more information (and bear in mind the answer to
   the question on unsetting the schg flag).

   9.26. I just changed /etc/newsyslog.conf. How can I check if it
   does what I expect?

   To see what newsyslog(8) will do use the following:

 % newsyslog -nrvv

   9.27. My time is wrong, how can I change the timezone?

   Use tzsetup(8).

     --------------------------------------------------------------

          Chapter 10 The X Window System and Virtual Consoles

   10.1. What is the X Window System?

   10.2. I want to run Xorg, how do I go about it?

   10.3. I tried to run X, but I get a "No devices detected." error
   when I type startx. What do I do now?

   10.4. Why does my mouse not work with X?

   10.5. My mouse has a fancy wheel. Can I use it in X?

   10.6. My laptop has a Synaptics touchpad. Can I use it in X?

   10.7. How do I use remote X displays?

   10.8. What is a virtual console and how do I make more?

   10.9. How do I access the virtual consoles from X?

   10.10. How do I start XDM on boot?

   10.11. Why do I get "Couldn't open console" when I run xconsole?

   10.12. Why does my PS/2 mouse misbehave under X?

   10.13. How do I reverse the mouse buttons?

   10.14. How do I install a splash screen and where do I find them?

   10.15. Can I use the Windows keys on my keyboard in X?

   10.16. How can I get 3D hardware acceleration for OpenGL(R)?

   10.1. 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 FreeBSD. The X.Org Foundation administers the X protocol
   standards, with the current reference implementation, version 11
   release 7.5.2, so you will often see references 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.

   10.2. 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 FreeBSD packages:

 # pkg_add -r xorg

   or on systems using pkg:

 # pkg install xorg

   After the installation of Xorg, follow the instructions from the
   X11 Configuration section of the FreeBSD Handbook.

   10.3. I tried to run X, but I get a "No devices detected." error
   when I type startx. What do I do now?

   Your 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 io(4). For more information, see at the init(8)
   manual page.

   There are two solutions to the problem: Set your securelevel back
   down to zero (usually in /etc/rc.conf), or run xdm(1) (or an
   alternative display manager) at boot time (before the securelevel
   is raised).

   See Q: 10.10. for more information about running xdm(1) at boot
   time.

   10.4. Why does my mouse not work with X?

   If you are using syscons(4) (the default console driver), you can
   configure FreeBSD to support a mouse pointer on each virtual
   screen. To avoid conflicting with X, syscons(4) supports a virtual
   device called /dev/sysmouse. All mouse events received from the
   real mouse device are written to the sysmouse(4) device via
   moused(8). To use your mouse on one or more virtual consoles, and
   use X, see Q: 4.4.1. and set up moused(8).

   Then edit /etc/X11/xorg.conf and make sure you have the following
   lines:

 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 sysmouse(4)) by
   adding the following line to /etc/devfs.conf (see devfs.conf(5)):

 link    sysmouse    mouse

   This link can be created by restarting devfs(5) with the following
   command (as root):

 # service devfs restart

   10.5. My mouse has a fancy wheel. Can I use it in X?

   Yes.

   You need to tell X that you have a 5 button mouse. To do this,
   simply add the lines Buttons 5 and ZAxisMapping 4 5 to the
   "InputDevice" section of /etc/X11/xorg.conf. For example, you
   might have the following "InputDevice" section in
   /etc/X11/xorg.conf.

   Example 10-1. "InputDevice" Section for Wheeled Mouse in Xorg
   Configuration File

 Section "InputDevice"
    Identifier      "Mouse1"
    Driver          "mouse"
    Option          "Protocol" "auto"
    Option          "Device" "/dev/sysmouse"
    Option          "Buttons" "5"
    Option          "ZAxisMapping" "4 5"
 EndSection

   Example 10-2. ".emacs" Example for Naive Page Scrolling with
   Wheeled Mouse (optional)

 ;; wheel mouse
 (global-set-key [mouse-4] 'scroll-down)
 (global-set-key [mouse-5] 'scroll-up)

   10.6. My laptop has a Synaptics touchpad. Can I use it in X?

   Yes, you will have to configure a few things to make it work.

   If you plan to use the Xorg synaptics driver you must remove
   moused_enable from rc.conf. Xorg can not use the synaptics mouse
   if the moused already sits on /dev/psm0.

   To enable synaptics in the psm(4) driver you need to add the
   following into /boot/loader.conf:

 hw.psm.synaptics_support="1"

   You also need the following into 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"

   10.7. 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, simply start X with the optional
   -listen_tcp argument:

 % startx -listen_tcp

   10.8. What is a virtual console and how do I make more?

   Virtual consoles, put simply, enable you to have 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. You can then type
   in your login name and password and start working (or playing!) on
   the first virtual console.

   At some point, you will probably wish to start another session,
   perhaps to look at documentation for a program you are running or
   to read your mail while waiting for an FTP transfer to finish.
   Just do Alt+F2 (hold down Alt and press F2), and you will find a
   login prompt waiting for you on the second "virtual console"! When
   you want to go back to the original session, do Alt+F1.

   The default FreeBSD installation has eight virtual consoles
   enabled. Alt+F1, Alt+F2, Alt+F3, and so on will switch between
   these virtual consoles.

   To enable more of them, edit /etc/ttys (see 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

   Use as many or as few as you want. The more virtual terminals you
   have, the more resources that are used; this can be important if
   you have 8 MB RAM or less. You may also want to change the secure
   to insecure.

     Note: Versions of FreeBSD prior to 9.0 used the " cons25"
     terminal type, and not " xterm". Existing entries in /etc/ttys
     can be used on which to base new additions.

     Important: If you want to run an X server you must leave at
     least one virtual terminal unused (or turned off) for it to use.
     That is to say that if you want to have a login prompt pop up
     for all twelve of your Alt-function keys, you are out of luck -
     you can only do this for eleven of them if you also want to run
     an X server on the same machine.

   The easiest way to disable a console is by turning it off. For
   example, if you had the full 12 terminal allocation mentioned
   above and you wanted to run X, you would change settings for
   virtual terminal 12 from:

 ttyvb   "/usr/libexec/getty Pc"         xterm  on  secure

   to:

 ttyvb   "/usr/libexec/getty Pc"         xterm  off secure

   If your keyboard has only ten function keys, you would end up
   with:

 ttyv9   "/usr/libexec/getty Pc"         xterm  off secure
 ttyva   "/usr/libexec/getty Pc"         xterm  off secure
 ttyvb   "/usr/libexec/getty Pc"         xterm  off secure

   (You could also just delete these lines.)

   Next, the easiest (and cleanest) way to activate the virtual
   consoles is to reboot. However, if you really do not want to
   reboot, you can just shut down the X Window system and execute (as
   root):

 # kill -HUP 1

   It is imperative that you completely shut down X Window if it is
   running, before running this command. If you do not, your system
   will probably appear to hang or lock up after executing kill.

   10.9. How do I access the virtual consoles from X?

   Use Ctrl+Alt+Fn to switch back to a virtual console. Ctrl+Alt+F1
   would return you to the first virtual console.

   Once you are back to a text console, you can then use Alt+Fn as
   normal to move between them.

   To return to the X session, you must switch to the virtual console
   running X. If you invoked X from the command line, (e.g., using
   startx) then the X session will attach to the next unused virtual
   console, not the text console from which it was invoked. If you
   have eight active virtual terminals then X will be running on the
   ninth, and you would use Alt+F9 to return.

   10.10. How do I start XDM on boot?

   There are two schools of thought on how to start xdm(1). One
   school starts xdm from /etc/ttys (see ttys(5)) using the supplied
   example, while the other simply runs xdm from rc.local (see 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 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 init(8). The rc(8) method makes it easy to
   kill xdm if there is a problem starting the X server.

   If loaded from rc(8), xdm should be started without any arguments
   (i.e., as a daemon). xdm must start after 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.

   If you are to start xdm from /etc/ttys, there still is a chance of
   conflict between xdm and 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 FreeBSD kernel numbers the vty from zero.

   10.11. Why do I get "Couldn't open console" when I run xconsole?

   If you start X 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 fbtab(5) file
   exists to solve such problems.

   In a nutshell, make sure an uncommented line of the form is in
   /etc/fbtab (see fbtab(5)):

 /dev/ttyv0 0600 /dev/console

   It will ensure that whomever logs in on /dev/ttyv0 will own the
   console.

   10.12. Why does my PS/2 mouse misbehave under X?

   Your mouse and the mouse driver may have somewhat become out of
   synchronization.

   In rare cases the driver may erroneously report synchronization
   problem and you may see the kernel message:

 psmintr: out of sync (xxxx != yyyy)

   and notice that your mouse does not work properly.

   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.

   10.13. How do I reverse the mouse buttons?

   Run the command xmodmap -e "pointer = 3 2 1" from .xinitrc or
   .xsession.

   10.14. 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 FreeBSD Handbook.

   10.15. Can I use the Windows keys on my keyboard in X?

   Yes. All you need to do is use xmodmap(1) to define what function
   you wish them to perform.

   Assuming all "Windows" keyboards are standard then 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.

 # xmodmap -e "keycode 115 = comma"

   To have the Windows key-mappings enabled automatically every time
   you start X 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, you could 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 your window manager, as
   demonstrated further down.

   To do this put the following in ~/.xmodmaprc.

 keycode 115 = F13
 keycode 116 = F14
 keycode 117 = F15

   If you use the x11-wm/fvwm2 port, for example, you 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 (application) menu even if the cursor is not on
   the desktop, which is useful if you do not have any part of the
   desktop visible (and the logo on the key matches its
   functionality).

   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

   10.16. How can I get 3D hardware acceleration for OpenGL(R)?

   The availability of 3D acceleration depends on the version of Xorg
   that you are using and the type of video chip you have. If you
   have an nVidia chip, you can use the binary drivers provided for
   FreeBSD by installing one of the following ports:

     * The latest versions of nVidia cards are supported by the
       x11/nvidia-driver port.

     * nVidia cards like the GeForce2 MX/3/4 series are supported by
       the 96XX series of drivers, available in the
       x11/nvidia-driver-96xx port.

     * Even older cards, like GeForce and RIVA TNT are supported by
       the 71XX series of drivers, available in the
       x11/nvidia-driver-71xx port.

   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 ati(4), r128(4) and radeon(4).

     --------------------------------------------------------------

                         Chapter 11 Networking

   11.1. Where can I get information on "diskless booting"?

   11.2. Can a FreeBSD box be used as a dedicated network router?

   11.3. Can I connect my Windows box to the Internet via FreeBSD?

   11.4. Does FreeBSD support PPP?

   11.5. Does FreeBSD support NAT or Masquerading?

   11.6. How can I set up Ethernet aliases?

   11.7. Why can I not NFS-mount from a Linux box?

   11.8. Why does mountd keep telling me it "can't change attributes"
   and that I have a "bad exports list" on my FreeBSD NFS server?

   11.9. How do I enable IP multicast support?

   11.10. Why do I have to use the FQDN for hosts on my site?

   11.11. Why do I get an error, "Permission denied", for all
   networking operations?

   11.12. Why is my ipfw "fwd" rule to redirect a service to another
   machine not working?

   11.13. How can I redirect service requests from one machine to
   another?

   11.14. Where can I get a bandwidth management tool?

   11.15. Why do I get "/dev/bpf0: device not configured"?

   11.16. How do I mount a disk from a Windows machine that is on my
   network, like smbmount in Linux?

   11.17. What are these messages about: "Limiting icmp/open
   port/closed port response" in my log files?

   11.18. What are these "arp: unknown hardware address format" error
   messages?

   11.19. 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?

   11.1. Where can I get information on "diskless booting"?

   "Diskless booting" means that the FreeBSD box is booted over a
   network, and reads the necessary files from a server instead of
   its hard disk. For full details, please read the Handbook entry on
   diskless booting.

   11.2. Can a FreeBSD box be used as a dedicated network router?

   Yes. Please see the Handbook entry on advanced networking,
   specifically the section on routing and gateways.

   11.3. Can I connect my Windows box to the Internet via FreeBSD?

   Typically, people who ask this question have two PCs at home, one
   with FreeBSD and one with some version of Windows the idea is to
   use the FreeBSD box to connect to the Internet and then be able to
   access the Internet from the Windows box through the FreeBSD box.
   This is really just a special case of the previous question and
   works perfectly well.

   Dialup users must use -nat and set gateway_enable to YES in
   /etc/rc.conf. For more information, please see the ppp(8) manual
   page or the Handbook entry on user PPP.

   If you are using kernel-mode PPP or have an Ethernet connection to
   the Internet, you need to use natd(8). Please look at the natd
   section of the Handbook for a tutorial.

   11.4. Does FreeBSD support PPP?

   Yes. ppp(8) provides support for both incoming and outgoing
   connections.

   For more information on how to use this, please see the Handbook
   chapter on PPP.

   11.5. Does FreeBSD support NAT or Masquerading?

   Yes. If you want to use NAT over a user PPP connection, please see
   the Handbook entry on user PPP. If you want to use NAT over some
   other sort of network connection, please look at the natd section
   of the Handbook.

   11.6. How can I set up Ethernet aliases?

   If the alias is on the same subnet as an address already
   configured on the interface, then add netmask 0xffffffff to your
   ifconfig(8) command-line, as in the following:

 # ifconfig ed0 alias 192.0.2.2 netmask 0xffffffff

   Otherwise, just specify the network address and netmask as usual:

 # ifconfig ed0 alias 172.16.141.5 netmask 0xffffff00

   You can read more about this in the FreeBSD Handbook.

   11.7. 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:

 # mount -o -P linuxbox:/blah /mnt

   11.8. Why does mountd keep telling me it "can't change attributes"
   and that I have a "bad exports list" on my FreeBSD NFS server?

   The most frequent problem is not understanding the correct format
   of /etc/exports. Please review exports(5) and the NFS entry in the
   Handbook, especially the section on configuring NFS.

   11.9. How do I enable IP multicast support?

   FreeBSD supports multicast host operations by default. If you want
   your box to run as a multicast router, you need to recompile your
   kernel with the MROUTING option and run mrouted(8). FreeBSD will
   start mrouted(8) at boot time if the flag mrouted_enable is set to
   YES in /etc/rc.conf.

     Note: In recent FreeBSD releases, the mrouted(8) multicast
     routing daemon, the map-mbone(8) and mrinfo(8) utilities have
     been removed from the base system. These programs are now
     available in the FreeBSD Ports Collection as net/mrouted.

   11.10. Why do I have to use the FQDN for hosts on my site?

   See the answer in the FreeBSD Handbook.

   11.11. Why do I get an error, "Permission denied", for all
   networking operations?

   If you have compiled your kernel with the IPFIREWALL option, you
   need to be aware that the default policy is to deny all packets
   that are not explicitly allowed.

   If you had unintentionally misconfigured your system for
   firewalling, you can restore network operability by typing the
   following while logged in as root:

 # ipfw add 65534 allow all from any to any

   You can also set firewall_type="open" in /etc/rc.conf.

   For further information on configuring a FreeBSD firewall, see the
   Handbook chapter.

   11.12. Why is my ipfw "fwd" rule to redirect a service to another
   machine not working?

   Possibly because you want to do network address translation (NAT)
   and not just forward packets. A "fwd" rule does exactly what it
   says; it forwards packets. It does not actually change the data
   inside the packet. Say we have a rule like:

 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 natd(8) manual, or one
   of the several port redirecting utilities in the Ports Collection
   for a correct way to do this.

   11.13. How can I redirect service requests from one machine to
   another?

   You can redirect FTP (and other service) request with the
   sysutils/socket port. Simply replace the service's command line to
   call socket instead, like so:

 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.

   11.14. Where can I get a bandwidth management tool?

   There are three bandwidth management tools available for FreeBSD.
   dummynet(4) is integrated into FreeBSD as part of ipfw(4). ALTQ
   has been integrated into FreeBSD as part of pf(4). Bandwidth
   Manager from Emerging Technologies is a commercial product.

   11.15. Why do I get "/dev/bpf0: device not configured"?

   You are running a program that requires the Berkeley Packet Filter
   (bpf(4)), but it is not in your kernel. Add this to your kernel
   config file and build a new kernel:

 device bpf        # Berkeley Packet Filter

   11.16. 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 mount_smbfs(8) in the base system.

   11.17. What are these messages about: "Limiting icmp/open
   port/closed port response" in my log files?

   This is the kernel telling you that some activity is provoking it
   to send more ICMP or TCP reset (RST) responses than it thinks it
   should. 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 tells you how many packets the
   kernel would have sent if the limit was not in place, and the
   second number tells you the limit. You can control the limit using
   the net.inet.icmp.icmplim sysctl variable like this, where 300 is
   the limit in packets per second:

 # sysctl net.inet.icmp.icmplim=300

   If you do not want to see messages about this in your log files,
   but you still want the kernel to do response limiting, you can use
   the net.inet.icmp.icmplim_output sysctl variable to disable the
   output like this:

 # sysctl net.inet.icmp.icmplim_output=0

   Finally, if you want to disable response limiting, you can set the
   net.inet.icmp.icmplim sysctl variable (see above for an example)
   to 0. Disabling response limiting is discouraged for the reasons
   listed above.

   11.18. What are these "arp: unknown hardware address format" error
   messages?

   This means that some device on your local Ethernet is using a MAC
   address in a format that FreeBSD does not recognize. This is
   probably caused by someone experimenting with an Ethernet card
   somewhere else on the network. You will see this most commonly on
   cable modem networks. It is harmless, and should not affect the
   performance of your FreeBSD machine.

   11.19. 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.

     --------------------------------------------------------------

                          Chapter 12 Security

   12.1. What is a sandbox?

   12.2. What is securelevel?

   12.3. BIND (named) is listening on some high-numbered ports. What
   is going on?

   12.4. The sendmail daemon is listening on port 587 as well as the
   standard port 25! What is going on?

   12.5. What is this UID 0 toor account? Have I been compromised?

   12.1. 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 said to be able to "play" inside the walls.
       That is, nothing the process does in regards to executing code
       is supposed to be able to breech the walls so you do not have
       to do a detailed audit of its code 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 security(7) and named(8) man pages.

       Take the ntalk service, for example (see 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 (i.e., / 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.

   12.2. 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 (i.e., 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, simply
   execute the following command:

 # sysctl -n kern.securelevel

   The output contains the current value of the securelevel. If it is
   positive (i.e., greater than 0), at least some of the
   securelevel's protections are enabled.

   The securelevel of a running system can not be lowered as this
   would defeat its purpose. If you need to do a task that requires
   that the securelevel be non-positive (e.g., an installworld or
   changing the date), you will have to change the securelevel
   setting in /etc/rc.conf (you want to look for the kern_securelevel
   and kern_securelevel_enable variables) and reboot.

   For more information on securelevel and the specific things all
   the levels do, please consult the init(8) manual page.

     Warning: Securelevel is not a silver bullet; it has many known
     deficiencies. More often than not, it provides a false sense of
     security.

     One of its biggest problems is that in order for it to be at all
     effective, all files used in the boot process up until the
     securelevel is set must be protected. If an attacker can get the
     system to execute their code prior to the securelevel being set
     (which happens quite late in the boot process since some things
     the system must do at start-up cannot be done at an elevated
     securelevel), its protections are invalidated. While this task
     of protecting all files used in the boot process is not
     technically impossible, if it is achieved, system maintenance
     will become a nightmare since one would have to take the system
     down, at least to single-user mode, to modify a configuration
     file.

     This point and others are often discussed on the mailing lists,
     particularly the FreeBSD security mailing list. Please search
     the archives here for an extensive discussion. A more
     fine-grained mechanism is preferred.

   12.3. BIND (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. If you
   want to get past that firewall, you can try the avoid-v4-udp-ports
   and avoid-v6-udp-ports options to avoid selecting random port
   numbers within a blocked range.

     Warning: If a port number (like 53) is specified via the
     query-source or query-source-v6 options in
     /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 your
   sockstat(1) output and notice odd things!

   12.4. 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.

   12.5. What is this UID 0 toor account? Have I been compromised?

   Do not worry. toor is an "alternative" superuser account (toor is
   root spelt backwards). Previously it was created when the bash(1)
   shell was installed but now it is created by default. It is
   intended to be used with a non-standard shell so you do not have
   to change root's default shell. This is important as shells which
   are not part of the base distribution (for example a shell
   installed from ports or packages) are likely to be 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 /usr (or
   whatever file system contains /usr/local/bin) is not mounted for
   some reason, root will not be able to log in to fix a problem
   (although if you reboot into single user mode you will be prompted
   for 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 you cannot log in using toor as it does
   not have a password, so log in as root and set a password for toor
   if you want to use it.

     --------------------------------------------------------------

                             Chapter 13 PPP

   13.1. I cannot make ppp(8) work. What am I doing wrong?

   13.2. Why does ppp(8) hang when I run it?

   13.3. Why will ppp(8) not dial in -auto mode?

   13.4. What does "No route to host" mean?

   13.5. Why does my connection drop after about 3 minutes?

   13.6. Why does my connection drop under heavy load?

   13.7. Why does my connection drop after a random amount of time?

   13.8. Why does my connection hang after a random amount of time?

   13.9. The remote end is not responding. What can I do?

   13.10. ppp(8) has hung. What can I do?

   13.11. I keep seeing errors about magic being the same. What does
   it mean?

   13.12. LCP negotiations continue until the connection is closed.
   What is wrong?

   13.13. Why does ppp(8) lock up when I shell out to test it?

   13.14. Why does ppp(8) over a null-modem cable never exit?

   13.15. Why does ppp(8) dial for no reason in -auto mode?

   13.16. What do these CCP errors mean?

   13.17. Why does ppp(8) not log my connection speed?

   13.18. Why does ppp(8) ignore the \ character in my chat script?

   13.19. Why does ppp(8) get a "Segmentation fault", but I see no
   ppp.core

   13.20. Why does the process that forces a dial in -auto mode never
   connect?

   13.21. Why do most games not work with the -nat switch?

   13.22. What are FCS errors?

   13.23. None of this helps - I am desperate! What can I do?

   13.1. I cannot make ppp(8) work. What am I doing wrong?

   You should first read the ppp(8) manual page and the PPP section
   of the handbook. Enable logging with the following command:

 set log Phase Chat Connect Carrier lcp ipcp ccp command

   This command may be typed at the ppp(8) command prompt or it may
   be entered in the /etc/ppp/ppp.conf configuration file (the start
   of the default section is the best place to put it). Make sure
   that /etc/syslog.conf (see syslog.conf(5)) contains the lines
   below and the file /var/log/ppp.log exists:

 !ppp
 *.*        /var/log/ppp.log

   You can now find out a lot about what is going on from the log
   file. Do not worry if it does not all make sense. If you need to
   get help from someone, it may make sense to them.

   13.2. Why does ppp(8) hang when I run it?

   This is usually because your hostname will not resolve. The best
   way to fix this is to make sure that /etc/hosts is consulted by
   your resolver first by editing /etc/host.conf and putting the
   hosts line first. Then, simply put an entry in /etc/hosts for your
   local machine. If you have no local network, change your localhost
   line:

 127.0.0.1        foo.example.com foo localhost

   Otherwise, simply add another entry for your host. Consult the
   relevant manual pages for more details.

   You should be able to successfully ping -c1 `hostname` when you
   are done.

   13.3. Why will ppp(8) not dial in -auto mode?

   First, check that you have got a default route. By running netstat
   -rn (see netstat(1)), you should see two entries like this:

 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

   This is assuming that you have used the addresses from the
   handbook, the manual page, or from ppp.conf.sample. If you do not
   have a default route, it may be because you forgot to add the
   HISADDR line to ppp.conf.

   Another reason for the default route line being missing is that
   you have mistakenly set up a default router in your /etc/rc.conf
   (see rc.conf(5)) file and you have omitted the line below from
   ppp.conf:

 delete ALL

   If this is the case, go back to the Final System Configuration
   section of the handbook.

   13.4. What does "No route to host" mean?

   This error is usually due that the following section is missing in
   your /etc/ppp/ppp.linkup:

 MYADDR:
   delete ALL
   add 0 0 HISADDR

   This is only necessary if you have a dynamic IP address or do not
   know the address of your gateway. If you are using interactive
   mode, you can type the following 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.

   13.5. 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 telnet(1) or pppctl(8).
   Refer to the ppp(8) man page for further details.

   13.6. Why does my connection drop under heavy load?

   If you have Link Quality Reporting (LQR) configured, it is
   possible that too many LQR packets are lost between your machine
   and the peer. 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

   13.7. 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, your modem may hang up because it thinks
   (incorrectly) 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.

   13.8. 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.

   If you are using an external modem, you can simply try using
   ping(8) to see if the TD light is flashing when you transmit data.
   If it flashes (and 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, you will need to use the set server command in
   ppp.conf. When the hang occurs, connect to ppp(8) using pppctl(8).
   If your network connection suddenly revives (PPP was revived due
   to the activity on the diagnostic socket) or if you cannot connect
   (assuming the set socket command succeeded at startup time), the
   problem is local. If you can connect and things are still hung,
   enable local async logging with set log local async and use
   ping(8) from another window or terminal to make use of the link.
   The async logging will show you 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, you now
   have two possibilities:

     * If the problem is remote, read on entry Q: 13.9..

     * If the problem is local, read on entry Q: 13.10..

   13.9. The remote end is not responding. What can I do?

   There is very little you can do about this. Most ISPs will refuse
   to help if you are not running a Microsoft(R) OS. You can enable
   lqr in your ppp.conf, allowing ppp(8) to detect the remote failure
   and hang up, but this detection is relatively slow and therefore
   not that useful. You may want to avoid telling your ISP that you
   are running user-PPP.

   First, try disabling all local compression by adding the following
   to your 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 will
   provide good ammunition when you contact your ISP (although it may
   make it apparent that you are not running a Microsoft product).

   Before contacting your 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 your 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 you why their side is having a problem.

   13.10. ppp(8) has hung. What can I do?

   Your best bet here is to rebuild ppp(8) with debugging
   information, and then use gdb(1) to grab a stack trace from the
   ppp process that is stuck. To rebuild the ppp utility with
   debugging information, you can type:

 # cd /usr/src/usr.sbin/ppp
 # env DEBUG_FLAGS='-g' make clean
 # env DEBUG_FLAGS='-g' make install

   Then you should restart ppp and wait until it hangs again. When
   the debug build of ppp hangs, start gdb on the stuck process by
   typing:

 # gdb ppp `pgrep ppp`

   At the gdb prompt, you can use the bt or where commands to get a
   stack trace. Save the output of your gdb session, and "detach"
   from the running process by typing quit.

   13.11. I keep seeing errors about magic being the same. What does
   it mean?

   Occasionally, just after connecting, you may see 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, you will see repeated configure requests and
   configure acknowledgments in the log file until ppp(8) eventually
   gives up and closes the connection.

   This normally happens on server machines with slow disks that are
   spawning a getty(8) on the port, and executing 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 getty(8) exiting and ppp(8) starting, the
   client-side ppp(8) starts sending Line Control Protocol (LCP)
   packets. Because ECHO is still switched on for the port on the
   server, the client 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 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 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 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 ppp(8) to wait for the server to initiate LCP
   negotiations. Some servers however may never initiate
   negotiations. If this is the case, you can do something like:

 set openmode active 3

   This tells ppp(8) to be passive for 3 seconds, and then to start
   sending LCP requests. If the peer starts sending requests during
   this period, ppp(8) will immediately respond rather than waiting
   for the full 3 second period.

   13.12. LCP negotiations continue until the connection is closed.
   What is wrong?

   There is currently an implementation mis-feature in 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. You should also use this
   command to limit the amount of time that 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.

   13.13. Why does ppp(8) lock up when I shell out to test it?

   When you execute the shell or ! command, ppp(8) executes a shell
   (or if you have passed any arguments, ppp(8) will execute those
   arguments). The ppp program will wait for the command to complete
   before continuing. If you attempt to use the PPP link while
   running the command, the link will appear to have frozen. This is
   because 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 ppp(8) can continue to
   service the link.

   13.14. Why does ppp(8) over a null-modem cable never exit?

   There is no way for 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.

   13.15. Why does ppp(8) dial for no reason in -auto mode?

   If ppp(8) is dialing unexpectedly, you must determine the cause,
   and set up Dial filters (dfilters) 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, you will see the reason logged
   with a convenient timestamp next to it.

   You can now 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
   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 your
   demand-dial capabilities - most programs will need a DNS lookup
   before doing any other network related things.

   In the DNS case, you should try to determine what is actually
   trying to resolve a host name. A lot of the time, sendmail(8) is
   the culprit. You should make sure that you tell sendmail not to do
   any DNS lookups in its configuration file. See the section on
   using email with a dialup connection in the FreeBSD Handbook for
   details on how to create your own configuration file and what
   should go into it. 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, sendmail is run with -bd -q30m, telling it to run the
   queue every 30 minutes) or until a sendmail -q is done (perhaps
   from your ppp.linkup).

   13.16. 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 ppp(8) is trying to negotiate Predictor1
   compression, and the peer does not want to negotiate any
   compression at all. The messages are harmless, but if you wish to
   remove them, you can disable Predictor1 compression locally too:

 disable pred1

   13.17. Why does ppp(8) not log my connection speed?

   To log all lines of your modem "conversation", you must enable the
   following:

 set log +connect

   This will make ppp(8) log everything up until the last requested
   "expect" string.

   If you wish to see your connect speed and are using PAP or CHAP
   (and therefore do not have anything to "chat" after the CONNECT in
   the dial script - no set login script), you must make sure that
   you instruct ppp(8) to "expect" the whole CONNECT line, something
   like this:

 set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 4 \
   \"\" ATZ OK-ATZ-OK ATDT\\T TIMEOUT 60 CONNECT \\c \\n"

   Here, we get our CONNECT, send nothing, then expect a line-feed,
   forcing ppp(8) to read the whole CONNECT response.

   13.18. Why does ppp(8) ignore the \ character in my chat script?

   The ppp utility parses each line in your config 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, you must 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
   (see the manual page). As a result of this double-parsing, you
   must remember to use the correct number of escapes.

   If you wish to actually send a \ character to (say) your modem,
   you would need 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

   13.19. Why does ppp(8) get a "Segmentation fault", but I see no
   ppp.core

   The ppp utility (or any other program for that matter) should
   never dump core. Because ppp(8) runs setuid (with an effective
   user ID of 0), the operating system will not write core image of
   ppp(8) to disk before terminating it. If, however ppp(8) is
   actually terminating due to a segmentation violation or some other
   signal that normally causes core to be dumped, and you are sure
   you are using the latest version (see the start of this section),
   then you should install the system sources and do the following:

 # cd /usr/src/usr.sbin/ppp
 # echo STRIP= >> /etc/make.conf
 # echo CFLAGS+=-g >> /etc/make.conf
 # make install clean

   You will now have a debuggable version of ppp(8) installed. You
   will have to be root to run ppp(8) as all of its privileges have
   been revoked. When you start ppp(8), take a careful note of what
   your current directory was at the time.

   Now, if and when ppp(8) receives the segmentation violation, it
   will dump a core file called ppp.core. You should then do the
   following:

 % su
 # gdb /usr/sbin/ppp ppp.core
 (gdb) bt
 .....
 (gdb) f 0
 ....
 (gdb) i args
 ....
 (gdb) l
 .....

   All of this information should be given alongside your question,
   making it possible to diagnose the problem.

   If you are familiar with gdb(1), you may wish to find out some
   other bits and pieces such as what actually caused the dump or the
   addresses and values of the relevant variables.

   13.20. Why does the process that forces a dial in -auto mode never
   connect?

   This was a known problem with ppp(8) set up to negotiate a dynamic
   local IP number with the peer in -auto mode. It has been fixed a
   long time ago - search the manual page for iface.

   The problem was that when that initial program calls connect(2),
   the IP number of the tun(4) interface is assigned to the socket
   endpoint. The kernel creates the first outgoing packet and writes
   it to the tun(4) device. ppp(8) then reads the packet and
   establishes a connection. If, as a result of ppp(8)'s dynamic IP
   assignment, the interface address is changed, the original socket
   endpoint will be invalid. Any subsequent packets sent to the peer
   will usually be dropped. Even if they are not, any responses will
   not route back to the originating machine as the IP number is no
   longer owned by that machine.

   There are several theoretical ways to approach this problem. It
   would be nicest if the peer would re-assign the same IP number if
   possible. The current version of ppp(8) does this, but most other
   implementations do not.

   The easiest method from our side would be to never change the
   tun(4) interface IP number, but instead to change all outgoing
   packets so that the source IP number is changed from the interface
   IP to the negotiated IP on the fly. This is essentially what the
   iface-alias option in the latest version of ppp(8) is doing (with
   the help of libalias(3) and ppp(8)'s -nat switch) - it is
   maintaining all previous interface addresses and NATing them to
   the last negotiated address.

   Another alternative (and probably the most reliable) would be to
   implement a system call that changes all bound sockets from one IP
   to another. ppp(8) would use this call to modify the sockets of
   all existing programs when a new IP number is negotiated. The same
   system call could be used by DHCP clients when they are forced to
   call the bind() function for their sockets.

   Yet another possibility is to allow an interface to be brought up
   without an IP number. Outgoing packets would be given an IP number
   of 255.255.255.255 up until the first SIOCAIFADDR ioctl(2) is
   done. This would result in fully binding the socket. It would be
   up to ppp(8) to change the source IP number, but only if it is set
   to 255.255.255.255, and only the IP number and IP checksum would
   need to change. This, however is a bit of a hack as the kernel
   would be sending bad packets to an improperly configured
   interface, on the assumption that some other mechanism is capable
   of fixing things retrospectively.

   13.21. Why do most games not work with the -nat switch?

   The reason games and the like do not work when libalias(3) is in
   use is that the machine on the outside will try to open a
   connection or send (unsolicited) UDP packets to the machine on the
   inside. The NAT software does not know that it should send these
   packets to the interior machine.

   To make things work, make sure that the only thing running is the
   software that you are having problems with, then either run
   tcpdump(1) on the tun(4) interface of the gateway or enable ppp(8)
   TCP/IP logging (set log +tcp/ip) on the gateway.

   When you start the offending software, you should see packets
   passing through the gateway machine. When something comes back
   from the outside, it will be dropped (that is the problem). Note
   the port number of these packets then shut down the offending
   software. Do this a few times to see if the port numbers are
   consistent. If they are, then the following line in the relevant
   section of /etc/ppp/ppp.conf will make the software functional:

 nat port proto internalmachine:port port

   where proto is either tcp or udp, internalmachine is the machine
   that you want the packets to be sent to and port is the
   destination port number of the packets.

   You will not be able to use the software on other machines without
   changing the above command, and running the software on two
   internal machines at the same time is out of the question - after
   all, the outside world is seeing your entire internal network as
   being just a single machine.

   If the port numbers are not consistent, there are three more
   options:

    1. Submit support in libalias(3). Examples of "special cases" can
       be found in /usr/src/sys/netinet/libalias/alias_*.c
       (alias_ftp.c is a good prototype). This usually involves
       reading certain recognized outgoing packets, identifying the
       instruction that tells the outside machine to initiate a
       connection back to the internal machine on a specific (random)
       port and setting up a "route" in the alias table so that the
       subsequent packets know where to go.

       This is the most difficult solution, but it is the best and
       will make the software work with multiple machines.

    2. Use a proxy. The application may support socks5 for example,
       or may have a "passive" option that avoids ever requesting
       that the peer open connections back to the local machine.

    3. Redirect everything to the internal machine using nat addr.
       This is the sledge-hammer approach.

   13.22. 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 your link is bad (or if your serial driver is dropping
   packets), you will see the occasional FCS error. This is not
   usually worth worrying about although it does slow down the
   compression protocols substantially. If you have an external
   modem, make sure your cable is properly shielded from interference
   - this may eradicate the problem.

   If your link freezes as soon as you have connected and you see a
   large number of FCS errors, this may be because your link is not
   8-bit clean. Make sure your modem is not using software flow
   control (XON/XOFF). If your datalink must use software flow
   control, use the command set accmap 0x000a0000 to tell ppp(8) to
   escape the ^Q and ^S characters.

   Another reason for seeing too many FCS errors may be that the
   remote end has stopped talking PPP. You may want to enable async
   logging at this point to determine if the incoming data is
   actually a login or shell prompt. If you have a shell prompt at
   the remote end, it is possible to terminate ppp(8) without
   dropping the line by using close lcp (a following term) will
   reconnect you to the shell on the remote machine.

   If nothing in your log file indicates why the link might have been
   terminated, you should ask the remote administrator (your ISP?)
   why the session was terminated.

   13.23. None of this helps - I am desperate! What can I do?

   If all else fails, send as much information as you can, including
   your config files, how you are starting ppp(8), the relevant parts
   of your log file and the output of netstat -rn (before and after
   connecting) to the FreeBSD general questions mailing list and
   someone should point you in the right direction.

     --------------------------------------------------------------

                    Chapter 14 Serial Communications

   This section answers common questions about serial communications
   with FreeBSD. PPP is covered in the Networking section.

   14.1. Which multi-port serial cards are supported by FreeBSD?

   14.2. How do I get the boot: prompt to show on the serial console?

   14.3. How do I tell if FreeBSD found my serial ports or modem
   cards?

   14.4. How do I access the serial ports on FreeBSD?

   14.5. How do I enable support for a multiport serial card?

   14.6. Can I set the default serial parameters for a port?

   14.7. How can I enable dialup logins on my modem?

   14.8. How can I connect a dumb terminal to my FreeBSD box?

   14.9. Why can I not run tip or cu?

   14.1. Which multi-port serial cards are supported by FreeBSD?

   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 uart(4) and sio(4) to get more information on configuring
   such cards.

   14.2. How do I get the boot: prompt to show on the serial console?

   See this section of the handbook.

   14.3. How do I tell if FreeBSD found my serial ports or modem
   cards?

   As the FreeBSD kernel boots, it will probe for the serial ports in
   your system for which the kernel was configured. You can either
   watch your system closely for the messages it prints or run this
   command after your system is up and running:

 % dmesg | grep -E "^sio[0-9]"

   Here is some example output from the above command:

 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 shows two serial ports. The first is on IRQ 4, is using port
   address 0x3f8, and has a 16550A-type UART chip. The second uses
   the same kind of chip but is on IRQ 3 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 your system, or if you have added modem
   cards or have more serial ports than your kernel is configured
   for, just reconfigure your kernel. See section about building a
   kernel for more details.

   14.4. How do I access the serial ports on FreeBSD?

   The third serial port, sio2 (see sio(4), known as COM3 in DOS), 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?

   You use ttydX for dial-ins. 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 you open the cuadX device, 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, you can have remote users log in and you can
   still dial out with the same modem and the system will take care
   of all the conflicts.

   14.5. How do I enable support for a multiport serial card?

   Again, the section on kernel configuration provides information
   about configuring your kernel. For a multiport serial card, place
   an sio(4) line for each serial port on the card in the
   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).

   14.6. Can I set the default serial parameters for a port?

   See the Serial Communications section in the FreeBSD Handbook.

   14.7. How can I enable dialup logins on my modem?

   Please read the section about Dial-in Services in the FreeBSD
   Handbook.

   14.8. How can I connect a dumb terminal to my FreeBSD box?

   You can find this information in the Terminals section of the
   FreeBSD Handbook.

   14.9. Why can I not run tip or cu?

   On your system, the programs tip(1) and cu(1) can only access the
   /var/spool/lock directory via user uucp and group dialer. You can
   use the group dialer to control who has access to your modem or
   remote systems. Just add yourself to group dialer.

   Alternatively, you can let everyone on your system run tip(1) and
   cu(1) by typing:

 # chmod 4511 /usr/bin/cu
 # chmod 4511 /usr/bin/tip

     --------------------------------------------------------------

                   Chapter 15 Miscellaneous Questions

   15.1. FreeBSD a lot of swap space even when the computer has free
   memory left. Why?

   15.2. Why does top show very little free memory even when I have
   very few programs running?

   15.3. Why will chmod not change the permissions on symlinks?

   15.4. Can I run DOS binaries under FreeBSD?

   15.5. What do I need to do to translate a FreeBSD document into my
   native language?

   15.6. Why does my email to any address at FreeBSD.org bounce?

   15.7. Where can I find a free FreeBSD account?

   15.8. What is the cute little red guy's name?

   15.9. Can I use the BSD daemon image?

   15.10. Do you have any BSD daemon images I could use?

   15.11. I have seen an acronym or other term on the mailing lists
   and I do not understand what it means. Where should I look?

   15.12. Why should I care what color the bikeshed is?

   15.1. FreeBSD a lot of swap space even when the computer has free
   memory left. Why?

   FreeBSD will proactively move entirely idle, unused pages of main
   memory into swap in order to make more main memory available for
   active use. This heavy use of swap is balanced by using the extra
   free memory for cacheing.

   Note that while FreeBSD is proactive in this regard, it does not
   arbitrarily decide to swap pages when the system is truly idle.
   Thus you will not find your system all paged out when you get up
   in the morning after leaving it idle overnight.

   15.2. 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 your programs do not actively allocate is used within the
   FreeBSD kernel as disk cache. The values shown by 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 top(1) is good, provided it is not very low.

   15.3. Why will chmod not change the permissions on symlinks?

   Symlinks do not have permissions, and by default, chmod(1) will
   follow symlinks to change the permissions on the source file, if
   possible. So if you have a file, foo, and a symlink to that file,
   bar, then this command will always succeed.

 % 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, you have to use either -H or -L
   together with -R to make this work. See chmod(1) and symlink(7)
   for more information.

     Warning: -R does a recursive chmod(1). Be careful about
     specifying directories or symlinks to directories to chmod(1).
     If you want to change the permissions of a directory referenced
     by a symlink, use chmod(1) without any options and follow the
     symlink with a trailing slash (/). For example, if foo is a
     symlink to directory bar, and you want to change the permissions
     of foo (actually bar), you would do something like:

 % chmod 555 foo/

     With the trailing slash, chmod(1) will follow the symlink, foo,
     to change the permissions of the directory, bar.

   15.4. Can I run DOS binaries under FreeBSD?

   Yes, you can use emulators/doscmd, a DOS emulation program,
   available in the FreeBSD Ports Collection.

   If doscmd will not suffice, the add-on utility emulators/pcemu
   emulates an 8088 and enough BIOS services to run many DOS text
   mode applications. It requires the X Window System.

   You may also try emulators/dosbox from the FreeBSD Ports
   Collection. The main focus of this application is emulating old
   DOS games using the local file system for files.

   15.5. What do I need to do to translate a FreeBSD document into my
   native language?

   See the Translation FAQ in the FreeBSD Documentation Project
   Primer.

   15.6. 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 your 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.)

   15.7. Where can I find a free FreeBSD account?

   While FreeBSD does not provide open access to any of their
   servers, others do provide open access UNIX 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 FreeBSD. M-Net can be accessed via telnet
   and SSH and provides basic access to the entire FreeBSD software
   suite. However, network access is limited to members and patrons
   who donate to the system, which is run as a non-profit
   organization. M-Net also provides an bulletin board system and
   interactive chat.

   15.8. 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".

   You can learn more about the BSD daemon on his home page.

   15.9. Can I use the BSD daemon image?

   Perhaps. The BSD daemon is copyrighted by Marshall Kirk McKusick.
   You will want to check his Statement on the Use of the BSD Daemon
   Figure for detailed usage terms.

   In summary, you are free to use the image in a tasteful manner,
   for personal use, so long as appropriate credit is given. If you
   want to use him commercially, you must contact Kirk McKusick
   <mckusick@FreeBSD.org>. More details are available on the BSD
   Daemon's home page.

   15.10. Do you have any BSD daemon images I could use?

   You will find eps and Xfig drawings under
   /usr/share/examples/BSD_daemon/.

   15.11. I have seen an acronym or other term on the mailing lists
   and I do not understand what it means. Where should I look?

   Please see the FreeBSD Glossary.

   15.12. 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 sleep(1) should take fractional second
   arguments, Poul-Henning Kamp <phk@FreeBSD.org> posted a long
   message entitled "A bike shed (any color will do) on greener
   grass...". The appropriate portions of that message are quoted
   below.

     "What is it about this bike shed?" Some of you have asked me.    
                                                                    
     It is a long story, or rather it is an old story, but it is    
     quite short actually. C. Northcote Parkinson wrote a book in   
     the early 1960s, called "Parkinson's Law", which contains a    
     lot of insight into the dynamics of management.                
                                                                    
     [snip a bit of commentary on the book]                         
                                                                    
     In the specific example involving the bike shed, the other     
     vital component is an atomic power-plant, I guess that         
     illustrates the age of the book.                               
                                                                    
     Parkinson shows how you can go into the board of directors and 
     get approval for building a multi-million or even billion      
     dollar atomic power plant, but if you want to build a bike     
     shed you will be tangled up in endless discussions.            
                                                                    
     Parkinson explains that this is because an atomic plant is so  
     vast, so expensive and so complicated that people cannot grasp 
     it, and rather than try, they fall back on the assumption that 
     somebody else checked all the details before it got this far.  
     Richard P. Feynmann gives a couple of interesting, and very    
     much to the point, examples relating to Los Alamos in his      
     books.                                                         
                                                                    
     A bike shed on the other hand. Anyone can build one of those   
     over a weekend, and still have time to watch the game on TV.   
     So no matter how well prepared, no matter how reasonable you   
     are with your proposal, somebody will seize the chance to show 
     that he is doing his job, that he is paying attention, that he 
     is here.                                                       
                                                                    
     In Denmark we call it "setting your fingerprint". It is about  
     personal pride and prestige, it is about being able to point   
     somewhere and say "There! I did that." It is a strong trait in 
     politicians, but present in most people given the chance. Just 
     think about footsteps in wet cement.                           
          --Poul-Henning Kamp <phk@FreeBSD.org> on freebsd-hackers,   
                                                    October 2, 1999

     --------------------------------------------------------------

                     Chapter 16 The FreeBSD Funnies

   16.1. How cool is FreeBSD?

   16.2. Who is scratching in my memory banks??

   16.3. How many FreeBSD hackers does it take to change a lightbulb?

   16.4. Where does data written to /dev/null go?

   16.5. My colleague sits at the computer too much, how can I prank
   her?

   16.1. How cool is FreeBSD?

   Q. Has anyone done any temperature testing while running FreeBSD?
   I know Linux runs cooler than DOS, but have never seen a mention
   of FreeBSD. It seems to run really hot.

   A. No, but we have done numerous taste tests on blindfolded
   volunteers who have also had 250 micrograms of LSD-25 administered
   beforehand. 35% of the volunteers said that FreeBSD tasted sort of
   orange, whereas Linux tasted like purple haze. Neither group
   mentioned any significant variances in temperature. We eventually
   had to throw the results of this survey out entirely anyway when
   we found that too many volunteers were wandering out of the room
   during the tests, thus skewing the results. We think most of the
   volunteers are at Apple now, working on their new "scratch and
   sniff" GUI. It is a funny old business we are in!

   Seriously, FreeBSD uses the HLT (halt) instruction when the system
   is idle thus lowering its energy consumption and therefore the
   heat it generates. Also if you have ACPI (Advanced Configuration
   and Power Interface) configured, then FreeBSD can also put the CPU
   into a low power mode.

   16.2. Who is scratching in my memory banks??

   Q. Is there anything "odd" that FreeBSD does when compiling the
   kernel which would cause the memory to make a scratchy sound? When
   compiling (and for a brief moment after recognizing the floppy
   drive upon startup, as well), a strange scratchy sound emanates
   from what appears to be the memory banks.

   A. Yes! You will see frequent references to "daemons" in the BSD
   documentation, and what most people do not know is that this
   refers to genuine, non-corporeal entities that now possess your
   computer. The scratchy sound coming from your memory is actually
   high-pitched whispering exchanged among the daemons as they best
   decide how to deal with various system administration tasks.

   If the noise gets to you, a good fdisk /mbr from DOS will get rid
   of them, but do not be surprised if they react adversely and try
   to stop you. In fact, if at any point during the exercise you hear
   the satanic voice of Bill Gates coming from the built-in speaker,
   take off running and do not ever look back! Freed from the
   counterbalancing influence of the BSD daemons, the twin demons of
   DOS and Windows 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?

   16.3. How many FreeBSD hackers does it take to change a lightbulb?

   One thousand, one hundred and sixty-nine:

   Twenty-three to complain to -CURRENT about the lights being out;

   Four to claim that it is a configuration problem, and that such
   matters really belong on -questions;

   Three to submit PRs about it, one of which is misfiled under doc
   and consists only of "it's dark";

   One to commit an untested lightbulb which breaks buildworld, then
   back it out five minutes later;

   Eight to flame the PR originators for not including patches in
   their PRs;

   Five to complain about buildworld being broken;

   Thirty-one to answer that it works for them, and they must have
   updated at a bad time;

   One to post a patch for a new lightbulb to -hackers;

   One to complain that he had patches for this three years ago, but
   when he sent them to -CURRENT they were just ignored, and he has
   had bad experiences with the PR system; besides, the proposed new
   lightbulb is non-reflexive;

   Thirty-seven to scream that lightbulbs do not belong in the base
   system, that committers have no right to do things like this
   without consulting the Community, and WHAT IS -CORE DOING ABOUT
   IT!?

   Two hundred to complain about the color of the bicycle shed;

   Three to point out that the patch breaks style(9);

   Seventeen to complain that the proposed new lightbulb is under
   GPL;

   Five hundred and eighty-six to engage in a flame war about the
   comparative advantages of the GPL, the BSD license, the MIT
   license, the NPL, and the personal hygiene of unnamed FSF
   founders;

   Seven to move various portions of the thread to -chat and
   -advocacy;

   One to commit the suggested lightbulb, even though it shines
   dimmer than the old one;

   Two to back it out with a furious flame of a commit message,
   arguing that FreeBSD is better off in the dark than with a dim
   lightbulb;

   Forty-six to argue vociferously about the backing out of the dim
   lightbulb and demanding a statement from -core;

   Eleven to request a smaller lightbulb so it will fit their
   Tamagotchi if we ever decide to port FreeBSD to that platform;

   Seventy-three to complain about the SNR on -hackers and -chat and
   unsubscribe in protest;

   Thirteen to post "unsubscribe", "How do I unsubscribe?", or
   "Please remove me from the list", followed by the usual footer;

   One to commit a working lightbulb while everybody is too busy
   flaming everybody else to notice;

   Thirty-one to point out that the new lightbulb would shine 0.364%
   brighter if compiled with TenDRA (although it will have to be
   reshaped into a cube), and that FreeBSD should therefore switch to
   TenDRA instead of GCC;

   One to complain that the new lightbulb lacks fairings;

   Nine (including the PR originators) to ask "what is MFC?";

   Fifty-seven to complain about the lights being out two weeks after
   the bulb has been changed.

   Nik Clayton <nik@FreeBSD.org> 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 :-)

   Thomas Abthorpe <tabthorpe@FreeBSD.org> says: "None, real FreeBSD
   hackers are not afraid of the dark!"

   16.4. 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.

   16.5. 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.

     --------------------------------------------------------------

                       Chapter 17 Advanced Topics

   17.1. How can I learn more about FreeBSD's internals?

   17.2. How can I contribute to FreeBSD?

   17.3. What are snapshots and releases?

   17.4. Can I follow -CURRENT with limited Internet access?

   17.5. I have written a kernel extension, who do I send it to?

   17.6. How can I make the most of the data I see when my kernel
   panics?

   17.7. Why has dlsym() stopped working for ELF executables?

   17.8. How can I increase or reduce the kernel address space on
   i386?

   17.1. How can I learn more about FreeBSD's internals?

   See the FreeBSD Architecture Handbook.

   Additionally, much general UNIX knowledge is directly applicable
   to FreeBSD.

   17.2. How can I contribute to FreeBSD?

   Please see the article on Contributing to FreeBSD for specific
   advice on how to do this. Assistance is more than welcome!

   17.3. What are snapshots and releases?

   There are currently four active/semi-active branches in the
   FreeBSD Subversion Repository. (Earlier branches are only changed
   very rarely, which is why there are only four active branches of
   development):

     * RELENG_8 AKA 8-STABLE

     * RELENG_9 AKA 9-STABLE

     * HEAD AKA -CURRENT AKA 10-CURRENT

   HEAD is not an actual branch tag, like the others; it is simply a
   symbolic constant for "the current, non-branched development
   stream" which we simply refer to as -CURRENT.

   Right now, -CURRENT is the 10.X development stream; the 9-STABLE
   branch, RELENG_9, forked off from -CURRENT in September 2011 and
   the 8-STABLE branch, RELENG_8, forked off from -CURRENT in August
   2009.

   17.4. Can I follow -CURRENT with limited Internet access?

   Yes, you can do this without downloading the whole source tree by
   using the CTM facility.

   17.5. I have written a kernel extension, who do I send it to?

   Please take a look at the article on Contributing to FreeBSD to
   learn how to submit code.

   And thanks for the thought!

   17.6. 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

   When you see a message like this, it is not enough to just
   reproduce it and send it in. The instruction pointer value is
   important; unfortunately, it is also configuration dependent. In
   other words, the value varies depending on the exact kernel image
   that you are using. If you are using a GENERIC kernel image from
   one of the snapshots, then it is possible for somebody else to
   track down the offending function, but if you are running a custom
   kernel then only you can tell us where the fault occurred.

   What you should do is this:

    1. 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.

    2. When the system reboots, do the following:

 % 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, i.e.:

 % nm -n kernel.that.caused.the.panic | grep f0xxxxx

       If that does not yield any results, chop off another digit.
       Repeat until you get 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 kgdb(1) to generate a stack
   trace on the crash dump.

   In any case, the method is this:

    1. Make sure that the following line is included in your kernel
       configuration file (/usr/src/sys/arch/conf/MYKERNEL):

 makeoptions     DEBUG=-g          # Build kernel with gdb(1) debug symbols

    2. Change to the /usr/src directory:

 # cd /usr/src

    3. Compile the kernel:

 # make buildkernel KERNCONF=MYKERNEL

    4. Wait for make(1) to finish compiling.

    5. # make installkernel KERNCONF=MYKERNEL

    6. Reboot.

     Note: If you do not use the KERNCONF make variable a GENERIC
     kernel will be built and installed.

   The 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 kgdb(1).

   To make sure you capture a crash dump, you need edit /etc/rc.conf
   and set dumpdev to point to your swap partition (or AUTO). This
   will cause the rc(8) scripts to use the dumpon(8) command to
   enable crash dumps. You can also run dumpon(8) manually. After a
   panic, the crash dump can be recovered using savecore(8); if
   dumpdev is set in /etc/rc.conf, the rc(8) scripts will run
   savecore(8) automatically and put the crash dump in /var/crash.

     Note: FreeBSD crash dumps are usually the same size as the
     physical RAM size of your machine. That is, if you have 512 MB
     of RAM, you will get a 512 MB crash dump. Therefore you must
     make sure there is enough space in /var/crash to hold the dump.
     Alternatively, you run savecore(8) manually and have it recover
     the crash dump to another directory where you have 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, if you have 1 GB of RAM, you can limit the kernel's
     memory usage to 128 MB by this way, so that your crash dump size
     will be 128 MB instead of 1 GB.

   Once you have recovered the crash dump, you can get a stack trace
   with kgdb(1) as follows:

 % 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 you should use 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. Usually
   you have to read the stack trace from the bottom up to trace the
   exact sequence of events that lead to the crash. You can also use
   kgdb(1) to print out the contents of various variables or
   structures to examine the system state at the time of the crash.

     Tip: Now, if you are really insane and have a second computer,
     you can also configure kgdb(1) to do remote debugging such that
     you can use kgdb(1) on one system to debug the kernel on another
     system, including setting breakpoints, single-stepping through
     the kernel code, just like you can do with a normal user-mode
     program.

     Note: If you have DDB enabled and the kernel drops into the
     debugger, you can force a panic (and a crash dump) just 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.

   17.7. 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.

   If you want to search, using dlsym(), for symbols present in the
   main executable of a process, you need to link the executable
   using the --export-dynamic option to the ELF linker (ld(1)).

   17.8. 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. If you run a network-intensive server (e.g., a FTP or HTTP
   server), or you want to use ZFS, you might find that is not
   enough.

   Add the following line to your kernel configuration file to
   increase available space and rebuild your 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.)

     --------------------------------------------------------------

                       Chapter 18 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.

     --------------------------------------------------------------

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     --------------------------------------------------------------
