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      &tm-attrib.freebsd;
      &tm-attrib.adobe;
      &tm-attrib.ibm;
      &tm-attrib.ieee;
      &tm-attrib.intel;
      &tm-attrib.linux;
      &tm-attrib.microsoft;
      &tm-attrib.netbsd;
      &tm-attrib.opengroup;
      &tm-attrib.sgi;
      &tm-attrib.sun;
      &tm-attrib.general;
    </legalnotice>

    <releaseinfo>$FreeBSD$</releaseinfo>

    <abstract>
      <para>This is the FAQ for &os; versions &rel2.relx; and
	&rel.relx;.  Every effort has been made to make this FAQ as
	informative as possible; if you have any suggestions as to how
	it may be improved, please feel free to mail them to the
	&a.doc;.</para>

      <para>The latest version of
	this document is always available from the <ulink
	  url="http://www.FreeBSD.org/doc/en_US.ISO8859-1/books/faq/index.html">&os; website</ulink>.
	It may also be downloaded as one large <ulink
	  url="book.html">HTML</ulink> file with HTTP or as a variety
	of other formats from the <ulink
	  url="ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/">&os; FTP
	  server</ulink>.</para>
    </abstract>
  </bookinfo>

  <chapter id="introduction">
    <title>Introduction</title>

    <qandaset>
      <qandaentry>
	<question id="what-is-FreeBSD">
	  <para>What is &os;?</para>
	</question>

	<answer>
	  <para>&os; is a modern operating system for desktops,
	    laptops, servers, and embedded systems with
	    support for a large number of  <ulink
	      url="http://www.FreeBSD.org/platforms/">platforms</ulink>.</para>

	  <para>It is based on U.C.
	    Berkeley's <quote>4.4BSD-Lite</quote> release, with some
	    <quote>4.4BSD-Lite2</quote> enhancements.  It is also based
	    indirectly on William Jolitz's port of U.C. Berkeley's
	    <quote>Net/2</quote> to the &i386;, known as
	    <quote>386BSD</quote>, though very little of the 386BSD code
	    remains.</para>

	  <para>&os; is used by companies, Internet Service Providers,
	    researchers, computer professionals, students and home users
	    all over the world in their work, education and
	    recreation.</para>

	  <para>For more detailed information on &os;, please see the
	    <ulink
	      url="&url.books.handbook;/index.html">&os; Handbook</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="FreeBSD-goals">
	  <para>What is the goal of the &os; Project?</para>
	</question>

	<answer>
	  <para>The goal of the &os; Project is to provide a
	    stable and fast general purpose
	    operating system that may
	    be used for any purpose
	    without strings attached.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="bsd-license-restrictions">
	  <para>Does the &os; license have any restrictions?</para>
	</question>

	<answer>
	  <para>Yes.  Those restrictions do not control how you use the
	    code, merely how you treat the &os; Project itself.  If you
	    have serious license concerns, read the actual <ulink
	      url="http://www.FreeBSD.org/copyright/freebsd-license.html">license</ulink>.
	    For the simply curious, the license can be summarized like
	    this.</para>

	  <itemizedlist>
	    <listitem>
	      <para>Do not claim that you wrote this.</para>
	    </listitem>

	    <listitem>
	      <para>Do not sue us if it breaks.</para>
	    </listitem>

	    <listitem>
	      <para>Do not remove or modify the license.</para>
	    </listitem>
	  </itemizedlist>

	  <para>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
	    <quote>mission</quote> 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.</para>

	  <para>Code in our source tree which falls under the
	    <ulink
	      url="http://www.FreeBSD.org/copyright/COPYING">GNU General Public License (GPL)</ulink>
	    or <ulink
	      url="http://www.FreeBSD.org/copyright/COPYING.LIB">GNU Library General Public License (LGPL)</ulink>
	    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 <ulink
	      url="http://www.FreeBSD.org/copyright/freebsd-license.html">&os; license</ulink>
	    whenever possible.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="replace-current-OS">
	  <para>Can &os; replace my current operating system?</para>
	</question>

	<answer>
	  <para>For most people, yes.  But this question is not quite
	    that cut-and-dried.</para>

	  <para>Most people do not actually use an operating system.
	    They use applications.  The applications are what really use
	    the operating system.  &os; is designed to provide a robust
	    and full-featured environment for applications.  It supports
	    a wide variety of web browsers, office suites, email
	    readers, graphics programs, programming environments,
	    network servers, and just about everything else you might
	    want.  Most of these applications can be managed through the
	    <ulink
	      url="http://www.FreeBSD.org/ports/">Ports Collection</ulink>.</para>

	  <para>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 &os;, however.  If you want a solid office or
	    Internet server, a reliable workstation, or just the ability
	    to do your job without interruptions, &os; will almost
	    certainly do everything you need.  Many computer users
	    across the world, including both novices and experienced
	    &unix; administrators, use &os; as their only desktop
	    operating system.</para>

	  <para>If you are migrating to &os; 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; and &macos;, you may be interested in using
	    <ulink
	      url="http://www.pcbsd.org/">PC-BSD</ulink>, a &os; 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 <ulink
	      url="&url.books.handbook;/index.html">&os; Handbook</ulink>
	    are excellent places to start.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="why-called-FreeBSD">
	  <para>Why is it called &os;?</para>
	</question>

	<answer>
	  <itemizedlist>
	    <listitem>
	      <para>It may be used free of charge, even by commercial
		users.</para>
	    </listitem>

	    <listitem>
	      <para>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).</para>
	    </listitem>

	    <listitem>
	      <para>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).</para>
	    </listitem>
	  </itemizedlist>

	  <para>It is worth pointing out that the word
	    <quote>free</quote> is being used in two ways here, one
	    meaning <quote>at no cost</quote>, the other meaning
	    <quote>you can do whatever you like</quote>.  Apart from one
	    or two things you <emphasis>cannot</emphasis> do with the
	    &os; code, for example pretending you wrote it, you can
	    really do whatever you like with it.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="differences-to-other-bsds">
	  <para>What are the differences between &os; and NetBSD,
	    OpenBSD, and other open source BSD operating systems?</para>
	</question>

	<answer>
	  <para>James Howard wrote a good explanation of the history and
	    differences between the various projects,
	    called <ulink
	      url="http://www.freebsdworld.gr/freebsd/bsd-family-tree.html">The BSD Family Tree</ulink>
	    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.</para>

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

	  <para>The design goals of &os; are described in
	    <xref linkend="FreeBSD-goals"/>, above.  The design goals
	    of the other most popular BSDs may be summarized as
	    follows:</para>

	  <itemizedlist>
	    <listitem>
	      <para>OpenBSD aims for operating system security above
		all else.  The OpenBSD team wrote &man.ssh.1; and
		&man.pf.4;, which have both been ported to &os;.</para>
	    </listitem>

	    <listitem>
	      <para>NetBSD aims to be easily ported to other hardware
		platforms.</para>
	    </listitem>

	    <listitem>
	      <para>DragonFly&nbsp;BSD is a fork of &os;&nbsp;4.8 that has
		since developed many interesting features of its own,
		including the HAMMER file system and support for
		user-mode <quote>vkernels</quote>.</para>
	    </listitem>
	  </itemizedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="latest-version">
	  <para>What is the latest version of &os;?</para>
	</question>

	<answer>
	  <para>At any point in the development of &os;, there can be
	    multiple parallel branches.  &rel.relx; releases are
	    made from the &rel.stable; branch, and &rel2.relx;
	    releases are made from the &rel2.stable; branch.</para>

	  <para>Up until the release of 9.0, the
	    &rel2.relx; series was the one known as
	    <emphasis>-STABLE</emphasis>.  However, as of
	    &rel.head.relx;, the
	    &rel2.relx; branch will be designated for
	    an <quote>extended support</quote> status and receive only
	    fixes for major problems, such as security-related fixes.
	    <!--There will be no more releases made from the
	    &rel2.stable; branch, and it is considered a
	    <quote>legacy</quote> branch and most current work will only
	    become a part of &rel.stable; and &rel2.stable;.--></para>

	  <para>Version <ulink
	      url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/i386/&rel.current;-RELEASE/">&rel.current;</ulink>
	    is the latest release from the &rel.stable;
	    branch; it was released in &rel.current.date;.  Version
	    <ulink
	      url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/&rel2.current;-RELEASE/">&rel2.current;</ulink>
	    is the latest release from the &rel2.stable;
	    branch; it was released in &rel2.current.date;.</para>

	  <para>Briefly, <emphasis>-STABLE</emphasis> 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
	    <emphasis>-CURRENT</emphasis> snapshot.  Releases can come
	    from either branch, but <emphasis>-CURRENT</emphasis> should
	    only be used if you are prepared for its increased
	    volatility (relative to <emphasis>-STABLE</emphasis>, that
	    is).</para>

	  <para>Releases are made <link
	      linkend="release-freq">every few months</link>.  While
	    many people stay more up-to-date with the &os; sources (see
	    the questions on <link
	      linkend="current">&os.current;</link> and <link
	      linkend="stable">&os.stable;</link>) than that, doing so
	    is more of a commitment, as the sources are a moving
	    target.</para>

	  <para>More information on &os; releases can be found on the
	    <ulink
	      url="http://www.FreeBSD.org/releng/index.html#release-build">Release Engineering page</ulink>
	    and in &man.release.7;.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="current">
	  <para>What is <emphasis>&os;-CURRENT</emphasis>?</para>
	</question>

	<answer>
	  <para><ulink
	      url="&url.books.handbook;/current-stable.html#current">&os.current;</ulink>
	    is the development version of the operating system, which
	    will in due course become the new &os.stable; branch.  As
	    such, it is really only of interest to developers working on
	    the system and die-hard hobbyists.  See the <ulink
	      url="&url.books.handbook;/current-stable.html#current">relevant section</ulink>
	    in the <ulink
	      url="&url.books.handbook;/index.html">Handbook</ulink> for
	    details on running <emphasis>-CURRENT</emphasis>.</para>

	  <para>If you are not familiar with &os;
	    you should not use
	    &os.current;.  This branch sometimes evolves quite quickly
	    and due to mistake can be un-buildable at times.
	    People that use &os.current; are expected to be able to
	    analyze, debug, and report problems.</para>

	  <para>&os; <ulink
	      url="&url.base;/snapshots/">snapshot</ulink>
	    releases are made based on the current state of the
	    <emphasis>-CURRENT</emphasis> and
	    <emphasis>-STABLE</emphasis> branches.  The goals behind
	    each snapshot release are:</para>

	  <itemizedlist>
	    <listitem>
	      <para>To test the latest version of the installation
		software.</para>
	    </listitem>

	    <listitem>
	      <para>To give people who would like to run
		<emphasis>-CURRENT</emphasis> or
		<emphasis>-STABLE</emphasis> 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.</para>
	    </listitem>

	    <listitem>
	      <para>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.)</para>
	    </listitem>

	    <listitem>
	      <para>To ensure that all new features and fixes in need of
		testing have the greatest possible number of potential
		testers.</para>
	    </listitem>
	  </itemizedlist>

	  <para>No claims are made that any
	    <emphasis>-CURRENT</emphasis> snapshot can be considered
	    <quote>production quality</quote> 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
	    <emphasis>-STABLE</emphasis> snapshots.</para>

	  <para>Snapshot releases are directly available from <ulink
	      url="&url.base;/snapshots/">snapshot</ulink>.</para>

	  <para>Official snapshots are generated on a regular
	    basis for all actively developed branches.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="stable">
	  <para>What is the <emphasis>&os;-STABLE</emphasis>
	    concept?</para>
	</question>

	<answer>
	  <para>Back when &os;&nbsp;2.0.5 was released, &os; development
	    branched in two.  One branch was named <ulink
	      url="&url.books.handbook;/current-stable.html#stable">-STABLE</ulink>,
	    one <ulink
	      url="&url.books.handbook;/current-stable.html#current">-CURRENT</ulink>.
	    <emphasis>&os;-STABLE</emphasis> 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.
	    <emphasis>&os;-CURRENT</emphasis>, on the other hand, has
	    been one unbroken line since 2.0 was released, leading
	    towards &rel.current;-RELEASE and beyond.  For more detailed
	    information on branches see <quote><ulink
	      url="&url.articles.releng;/release-proc.html#rel-branch">&os; Release Engineering: Creating the Release Branch</ulink></quote>,
	    the status of the branches and the upcoming release schedule
	    can be found on the <ulink
	      url="http://www.FreeBSD.org/releng">Release Engineering Information</ulink> page.</para>

	  <para>&rel.current;-STABLE is the actively developed
	    <emphasis>-STABLE</emphasis> branch.  The latest release on
	    the &rel.current;-STABLE branch is &rel.current;-RELEASE,
	    which was released in &rel.current.date;.</para>

	  <para>The &rel.head; branch is the actively developed
	    <emphasis>-CURRENT</emphasis> branch toward the next
	    generation of &os;.  See <link
	      linkend="current">What is &os;-CURRENT?</link> for more
	    information on this branch.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="release-freq">
	  <para>When are &os; releases made?</para>
	</question>

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

	  <para>More information on the release engineering process
	    (including a schedule of upcoming releases) can be found on
	    the <ulink
	      url="http://www.FreeBSD.org/releng/index.html">release engineering</ulink>
	    pages on the &os; Web site.</para>

	  <para>For people who need or want a little more excitement,
	    binary snapshots are made weekly as discussed above.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="responsible">
	  <para>Who is responsible for &os;?</para>
	</question>

	<answer>
	  <para>The key decisions concerning the &os; project, such as
	    the overall direction of the project and who is allowed to
	    add code to the source tree, are made by a <ulink
	      url="&url.base;/administration.html#t-core">core team</ulink> of
	    9 people.  There is a much larger team of more than 350
	    <ulink
	      url="&url.articles.contributors;/article.html#staff-committers">committers</ulink>
	    who are authorized to make changes directly to the &os;
	    source tree.</para>

	  <para>However, most non-trivial changes are discussed in
	    advance in the <link linkend="mailing">mailing lists</link>,
	    and there are no restrictions on who may take part in the
	    discussion.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="where-get">
	  <para>Where can I get &os;?</para>
	</question>

	<answer>
	  <para>Every significant release of &os; is available via
	    anonymous FTP from the <ulink
	      url="ftp://ftp.FreeBSD.org/pub/FreeBSD/"> &os; FTP site</ulink>:</para>

	  <itemizedlist>
	    <listitem>
	      <para>The latest &rel.stable; release, &rel.current;-RELEASE
		can be found in the <ulink
		  url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/i386/&rel.current;-RELEASE/">&rel.current;-RELEASE directory</ulink>.</para>
	    </listitem>

	    <listitem>
	      <para><ulink url="&url.base;/snapshots/"> Snapshot</ulink>
		releases are made monthly for the <link
		  linkend="current">-CURRENT</link> and <link
		  linkend="stable">-STABLE</link> branch, these being of
		service purely to bleeding-edge testers and
		developers.</para>
	    </listitem>

	    <listitem>
	      <para>The latest &rel2.stable; release, &rel2.current;-RELEASE
		can be found in the <ulink
		  url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/&rel2.current;-RELEASE/">&rel2.current;-RELEASE directory</ulink>.</para>
	    </listitem>
	  </itemizedlist>

	  <para>Information about obtaining &os; on CD, DVD, and other
	    media can be found in <ulink
	      url="&url.books.handbook;/mirrors.html">the Handbook</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="access-pr">
	  <para>How do I access the Problem Report database?</para>
	</question>

	<answer>
	  <para>The Problem Report database of all user change requests
	    may be queried by using our web-based PR <ulink
	      url="http://www.FreeBSD.org/cgi/query-pr.cgi?query">query</ulink>
	    interface.</para>

	  <para>The &man.send-pr.1; command can be used to submit
	    problem reports and change requests via electronic mail.
	    Alternatively, the <ulink
	      url="http://www.freebsd.org/send-pr.html">web-based problem report submission interface</ulink>
	    can be used to submit problem reports through a web
	    browser.</para>

	  <para>Before submitting a problem report, please read <ulink
	      url="&url.articles.problem-reports;/article.html">Writing &os; Problem Reports</ulink>,
	    an article on how to write good problem reports.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="support">
    <title>Documentation and Support</title>

    <qandaset>
      <qandaentry>
	<question id="books">
	  <para>What good books are there about &os;?</para>
	</question>

	<answer>
	  <para>The project produces a wide range of documentation,
	    available online from this link: <ulink
	      url="http://www.FreeBSD.org/docs.html"></ulink>.  In addition, <link
	      linkend="bibliography">the Bibliography</link> at the end of this
	    FAQ, and <ulink
	      url="&url.books.handbook;/bibliography.html">the one in the Handbook</ulink>
	    reference other recommended books.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="doc-formats">
	  <para>Is the documentation available in other formats, such as
	    plain text (ASCII), or &postscript;?</para>
	</question>

	<answer>
	  <para>Yes.  The documentation is available in a number of
	    different formats and compression schemes on the &os; FTP
	    site, in the <ulink
	      url="ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/">/pub/FreeBSD/doc/</ulink>
	    directory.</para>

	  <para>The documentation is categorized in a number of
	    different ways.  These include:</para>

	  <itemizedlist>
	    <listitem>
	      <para>The document's name, such as <literal>faq</literal>,
		or <literal>handbook</literal>.</para>
	    </listitem>

	    <listitem>
	      <para>The document's language and encoding.  These are
		based on the locale names you will find under
		<filename class="directory">/usr/share/locale</filename> on your &os;
		system.  The current languages and encodings that we
		have for documentation are as follows:</para>

	      <informaltable frame="none" pgwide="1">
		<tgroup cols="2">
		  <thead>
		    <row>
		      <entry>Name</entry>

		      <entry>Meaning</entry>
		    </row>
		  </thead>

		  <tbody>
		    <row>
		      <entry><literal>en_US.ISO8859-1</literal></entry>

		      <entry>English (United States)</entry>
		    </row>

		    <row>
		      <entry><literal>bn_BD.ISO10646-1</literal></entry>

		      <entry>Bengali or Bangla (Bangladesh)</entry>
		    </row>

		    <row>
		      <entry><literal>da_DK.ISO8859-1</literal></entry>

		      <entry>Danish (Denmark)</entry>
		    </row>

		    <row>
		      <entry><literal>de_DE.ISO8859-1</literal></entry>

		      <entry>German (Germany)</entry>
		    </row>

		    <row>
		      <entry><literal>el_GR.ISO8859-7</literal></entry>

		      <entry>Greek (Greece)</entry>
		    </row>

		    <row>
		      <entry><literal>es_ES.ISO8859-1</literal></entry>

		      <entry>Spanish (Spain)</entry>
		    </row>

		    <row>
		      <entry><literal>fr_FR.ISO8859-1</literal></entry>

		      <entry>French (France)</entry>
		    </row>

		    <row>
		      <entry><literal>hu_HU.ISO8859-2</literal></entry>

		      <entry>Hungarian (Hungary)</entry>
		    </row>

		    <row>
		      <entry><literal>it_IT.ISO8859-15</literal></entry>

		      <entry>Italian (Italy)</entry>
		    </row>

		    <row>
		      <entry><literal>ja_JP.eucJP</literal></entry>

		      <entry>Japanese (Japan, EUC encoding)</entry>
		    </row>

		    <row>
		      <entry><literal>mn_MN.UTF-8</literal></entry>

		      <entry>Mongolian (Mongolia, UTF-8 encoding)</entry>
		    </row>

		    <row>
		      <entry><literal>nl_NL.ISO8859-1</literal></entry>

		      <entry>Dutch (Netherlands)</entry>
		    </row>

		    <row>
		      <entry><literal>no_NO.ISO8859-1</literal></entry>

		      <entry>Norwegian (Norway)</entry>
		    </row>

		    <row>
		      <entry><literal>pl_PL.ISO8859-2</literal></entry>

		      <entry>Polish (Poland)</entry>
		    </row>

		    <row>
		      <entry><literal>pt_BR.ISO8859-1</literal></entry>

		      <entry>Portuguese (Brazil)</entry>
		    </row>

		    <row>
		      <entry><literal>ru_RU.KOI8-R</literal></entry>

		      <entry>Russian (Russia, KOI8-R encoding)</entry>
		    </row>

		    <row>
		      <entry><literal>sr_YU.ISO8859-2</literal></entry>

		      <entry>Serbian (Serbia)</entry>
		    </row>

		    <row>
		      <entry><literal>tr_TR.ISO8859-9</literal></entry>

		      <entry>Turkish (Turkey)</entry>
		    </row>

		    <row>
		      <entry><literal>zh_CN.GB2312</literal></entry>

		      <entry>Simplified Chinese (China, GB2312
			encoding)</entry>
		    </row>

		    <row>
		      <entry><literal>zh_TW.Big5</literal></entry>

		      <entry>Traditional Chinese (Taiwan, Big5 encoding)</entry>
		    </row>
		  </tbody>
		</tgroup>
	      </informaltable>

	      <note>
		<para>Some documents may not be available in all
		  languages.</para>
	      </note>
	    </listitem>

	    <listitem>
	      <para>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:</para>

	      <informaltable frame="none" pgwide="1">
		<tgroup cols="2">
		  <thead>
		    <row>
		      <entry>Format</entry>

		      <entry>Meaning</entry>
		    </row>
		  </thead>

		  <tbody>
		    <row>
		      <entry><literal>html-split</literal></entry>

		      <entry>A collection of small, linked, HTML
			files.</entry>
		    </row>

		    <row>
		      <entry><literal>html</literal></entry>

		      <entry>One large HTML file containing the entire
			document</entry>
		    </row>

		    <row>
		      <entry><literal>pdf</literal></entry>

		      <entry>Adobe's Portable Document Format</entry>
		    </row>

		    <row>
		      <entry><literal>ps</literal></entry>

		      <entry>&postscript;</entry>
		    </row>

		    <row>
		      <entry><literal>rtf</literal></entry>

		      <entry>Microsoft's Rich Text Format</entry>
		    </row>

		    <row>
		      <entry><literal>txt</literal></entry>

		      <entry>Plain text</entry>
		    </row>
		  </tbody>
		</tgroup>
	      </informaltable>

	      <note>
		<para>Page numbers are not automatically updated when
		  loading Rich Text Format into Word.  Press <keycombo
		    action="simul"><keycap>Ctrl</keycap><keycap>A</keycap></keycombo>,
		  <keycombo
		    action="simul"><keycap>Ctrl</keycap><keycap>End</keycap></keycombo>,
		  <keycap>F9</keycap> after loading the document, to
		  update the page numbers.</para>
	      </note>
	    </listitem>

	    <listitem>
	      <para>The compression and packaging scheme.</para>

	      <orderedlist>
		<listitem>
		  <para>Where the format is
		    <literal>html-split</literal>, the files are bundled
		    up using &man.tar.1;.  The resulting
		    <filename>.tar</filename> file is then compressed
		    using the compression schemes detailed in the next
		    point.</para>
		</listitem>

		<listitem>
		  <para>All the other formats generate one file, called
		    <filename><replaceable>type</replaceable>.<replaceable>format</replaceable></filename>
		    (i.e., <filename>article.pdf</filename>,
		    <filename>book.html</filename>, and so on).</para>

		  <para>These files are then compressed using either
		    the <literal>zip</literal> or
		    <literal>bz2</literal> compression schemes.
		    &man.tar.1; can be used to uncompress these
		    files.</para>

		  <para>So the &postscript; version of the Handbook,
		    compressed using <literal>bzip2</literal> will be stored in a file
		    called <filename>book.ps.bz2</filename> in the
		    <filename class="directory">handbook/</filename> directory.</para>
		</listitem>
	      </orderedlist>
	    </listitem>
	  </itemizedlist>

	  <para>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.</para>

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

	  <screen>&prompt.root; <userinput>fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2</userinput>
&prompt.root; <userinput>tar xvf book.html-split.tar.bz2</userinput></screen>

	  <para>If the file is compressed,
	    <application>tar</application> will automatically
	    detect the appropriate format and decompress it correctly.
	    You will be left with a collection of
	    <filename>.html</filename> files.  The main one is called
	    <filename>index.html</filename>, 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mailing">
	  <para>Where do I find info on the &os; mailing lists?
	    What &os; news groups are available?</para>
	</question>

	<answer>
	  <para>You can find full information in the <ulink
	      url="&url.books.handbook;/eresources.html#eresources-mail">Handbook entry on mailing-lists</ulink>
	    and the <ulink
	      url="&url.books.handbook;/eresources-news.html">Handbook entry on newsgroups</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="irc">
	  <para>Are there &os; IRC (Internet Relay Chat)
	    channels?</para>
	</question>

	<answer>
	  <para>Yes, most major IRC networks host a &os; chat
	    channel:</para>

	  <itemizedlist>
	    <listitem>
	      <para>Channel <literal>#FreeBSDhelp</literal> on <ulink
		  url="http://www.efnet.org/index.php">EFNet</ulink> is
		a channel dedicated to helping &os; users.  They are
		much more sympathetic to questions than
		<literal>#FreeBSD</literal> is.</para>
	    </listitem>

	    <listitem>
	      <para>Channel <literal>##FreeBSD</literal> on <ulink
		  url="http://freenode.net/">Freenode</ulink> is a
		general help channel with many users at any time.
		The conversations have been known to run off-topic for a
		while, but priority is given to users with &os;
		questions.  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
		<literal>##freebsd-<replaceable>lang</replaceable></literal>
		as appropriate.</para>
	    </listitem>

	    <listitem>
	      <para>Channel <literal>#FreeBSD</literal> on <ulink
		  url="http://www.dal.net/">DALNET</ulink> is available at
		<hostid>irc.dal.net</hostid> in the US and
		<hostid>irc.eu.dal.net</hostid> in Europe.</para>
	    </listitem>

	    <listitem>
	      <para>Channel <literal>#FreeBSD</literal> on <ulink
		  url="http://www.undernet.org/">UNDERNET</ulink> is
		available at <hostid>us.undernet.org</hostid> in the US
		and <hostid>eu.undernet.org</hostid> in Europe.  Since
		it is a help channel, be prepared to read the documents
		you are referred to.</para>
	    </listitem>

	    <listitem>
	      <para>Channel <literal>#FreeBSD</literal> on
		<ulink url="http://www.rusnet.org.ru/">RUSNET</ulink>
		is a russian-language oriented channel dedicated
		to helping &os; users.  This is also good place
		for non-technical discussions.</para>
	    </listitem>

	    <listitem>
	      <para>Channel <literal>#bsdchat</literal> on <ulink
		  url="http://freenode.net/">Freenode</ulink> is a
		Traditional-Chinese (UTF-8 encoding) language oriented
		channel dedicated to helping &os; users.  This is also
		good place for non-technical discussions.</para>
	    </listitem>
	  </itemizedlist>

	  <para>The &os; wiki has a <ulink
	      url="http://wiki.freebsd.org/IrcChannels">good list</ulink>
	    of IRC channels.</para>

	  <para>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 <emphasis>all</emphasis> 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="forums">
	  <para>Are there any web based forums to discuss &os;?</para>
	</question>
	<answer>
	  <para>The official &os; forums are located at <ulink
	      url="http://forums.FreeBSD.org/">http://forums.FreeBSD.org/</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="training">
	  <para>Where can I get commercial &os; training and
	    support?</para>
	</question>

	<answer>
	  <para><ulink
	      url="http://www.ixsystems.com">iXsystems, Inc.</ulink>,
	    parent company of the <ulink
	      url="http://www.freebsdmall.com/">&os; Mall</ulink>,
	    provides commercial &os; and PC-BSD software <ulink
	      url="http://www.ixsystems.com/bsdsupport">support</ulink>,
	    in addition to &os; development and tuning solutions.</para>

	  <para>BSD Certification Group, Inc. provides system
	    administration certifications for DragonFly&nbsp;BSD, &os;, NetBSD,
	    OpenBSD.  If you are interested in them, visit <ulink
	      url="http://www.BSDCertification.org">their site</ulink>.</para>

	  <para>Any other organizations providing training and support
	    should contact the Project to be listed here.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="install">
    <chapterinfo>
      <author>
	<firstname>Nik</firstname>
	<surname>Clayton</surname>
	<affiliation>
	  <address><email>nik@FreeBSD.org</email></address>
	</affiliation>
      </author>
    </chapterinfo>

    <title>Installation</title>

    <qandaset>

      <qandaentry>
	<question id="which-architecture">
	  <para>Which platform should I download? I have a 64
	    bit capable &intel; CPU,
	    but I only see <literal>amd64</literal>.</para>
	</question>

	<answer>
	  <para>&arch.amd64; is the term &os; uses for 64-bit
	    compatible x86 architectures (also known as "x86-64"
	    or "x64").  Most modern computers
	    should use &arch.amd64;.  Older hardware should use
	    &arch.i386;.  If you are installing on a
	    non-x86-compatible architecture select the platform
	    which best matches the architecture you are
	    using.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="floppy-download">
	  <para>Which file do I download to get &os;?</para>
	</question>

	<answer>
	  <para>On the
	    <ulink url="http://www.freebsd.org/where.html">Getting &os;</ulink>
	    page select <literal>[iso]</literal> next to the
	    architecture you want to use.</para>

	  <para>Any of the following can be used:</para>

	  <informaltable frame="none" pgwide="1">
	    <tgroup cols="2">
	      <thead>
		<row>
		  <entry>file</entry>
		  <entry>description</entry>
		</row>
	      </thead>

	      <tbody>
		<row>
		  <entry><filename>disc1.iso</filename></entry>
		  <entry>Contains enough to install &os; and
		    a minimal set of packages.</entry>
		</row>

		<row>
		  <entry><filename>dvd1.iso</filename></entry>
		  <entry>Similar to <filename>disc1.iso</filename>
		    but with additional packages.</entry>
		</row>

		<row>
		  <entry><filename>memstick.img</filename></entry>
		  <entry>A bootable image sufficient for writing to a
		    USB stick.</entry>
		</row>

		<row>
		  <entry><filename>bootonly.iso</filename></entry>
		  <entry>A minimal image that requires network
		    access during installation to completely
		    install &os;.</entry>
		</row>
	      </tbody>
	    </tgroup>
	  </informaltable>

	  <para>&arch.pc98; users require these floppy images:
	    <filename>floppies/boot.flp</filename>,
	    <filename>floppies/kern1.flp</filename>,
	    <filename>floppies/kern2.flp</filename>, and
	    <filename>floppies/mfsroot1.flp</filename>.  These images
	    need
	    to be written onto floppies by tools like
	    &man.dd.1;.</para>

	  <para>Full instructions on this procedure and a little bit
	    more about installation issues in general can be found in
	    the <ulink
	      url="&url.books.handbook;/install.html">Handbook entry on installing &os;</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="floppy-image-too-large">
	  <para>What do I do if the images do not fit on a
	    single disk?</para>
	</question>

	<answer>
	  <para>Common mistakes when preparing the boot media
	    are:</para>

	  <itemizedlist>
	    <listitem>
	      <para>Not downloading the image in
		<emphasis>binary</emphasis> mode when using
		<acronym>FTP</acronym>.</para>

	      <para>Some FTP clients default their transfer mode to
		<emphasis>ascii</emphasis> 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
		<emphasis>exactly</emphasis> that on the server, then
		the download process is suspect.</para>

	      <para>To workaround: type <emphasis>binary</emphasis> at
		the FTP command prompt after getting connected to the
		server and before starting the download of the
		image.</para>
	    </listitem>

	    <listitem>
	      <para>Using the DOS <command>copy</command> command (or
		equivalent GUI tool) to transfer the boot image to
		floppy.</para>

	      <para>Programs like <command>copy</command> 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 <quote>raw</quote>, using the low-level
		tools (e.g., <command>fdimage</command> or
		<command>rawrite</command>) described in the <ulink
		  url="&url.books.handbook;/install.html">installation guide to &os;</ulink>.</para>
	    </listitem>
	  </itemizedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="install-instructions-location">
	  <para>Where are the instructions for installing &os;?</para>
	</question>

	<answer>
	  <para>Installation instructions for versions since
	    &os;&nbsp;9.0 can be found at <ulink
	      url="&url.books.handbook;/bsdinstall.html">Handbook entry on installing &os;</ulink>.
	    Older instructions can be found in the <ulink
	      url="&url.books.handbook;/install.html">legacy entry on installing &os;</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="need-to-run">
	  <para>What do I need to run &os;?</para>
	</question>

	<answer>
	  <para>For &os; you will need a 486 or better PC, with
	    64&nbsp;MB or more of RAM and at least 1&nbsp;GB of hard
	    disk space.</para>

	  <para>See also <xref linkend="hardware"/>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="custom-boot-floppy">
	  <para>How can I make my own custom release or install disk?</para>
	</question>

	<answer>
	  <para>Customized &os; installation media can be created by
	    building a custom release.  Follow the instructions in the
	    <ulink
	      url="&url.articles.releng;/article.html">Release Engineering</ulink>
	    article.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="windows-coexist">
	  <para>Can &windows; co-exist with &os;?</para>
	</question>

	<answer>
	  <para>If &windows; is installed first, then yes.
	    &os;'s boot manager
	    will then manage to boot &windows; and &os;.  If you install
	    &windows; second, it will boorishly overwrite your boot
	    manager without even asking.  If that happens, see the next
	    section.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="bootmanager-restore">
	  <para>Another operating system destroyed my Boot Manager.  How
	    do I get it back?</para>
	</question>

	<answer>
	  <para>This depends on what boot manager you have installed.
	    The &os; boot selection menu (likely what you are using
	    if you end up in this situation) can be reinstalled using
	    &man.boot0cfg.8;.  For example, to restore the boot menu
	    onto the disk <replaceable>ada0</replaceable>:</para>

	  <screen>&prompt.root; <userinput>boot0cfg -B ada0</userinput></screen>

	  <para>The non-interactive MBR bootloader can be installed using
	    &man.gpart.8;:</para>

	  <screen>&prompt.root; <userinput>gpart bootcode -b /boot/mbr ada0</userinput></screen>

	  <para>For more complex situations, including GPT disks, see &man.gpart.8;.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="no-install-cdrom">
	  <para>I booted from my ATAPI CD-ROM, but the install program
	    says no CD-ROM is found.  Where did it go?</para>
	</question>

	<answer>
	  <para>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 &os; cannot see it to complete the
	    install.</para>

	  <para>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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="need-complete-sources">
	  <para>Do I need to install the source?</para>
	</question>

	<answer>
	  <para>In general, no.  There is nothing in the base
	    system which requires the presence of the source to
	    operate.  Some ports, like <filename
	      role="package">sysutils/lsof</filename>, 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="need-kernel">
	  <para>Do I need to build a kernel?</para>
	</question>

	<answer>
	  <para>Usually not.  The supplied <literal>GENERIC</literal>
	    kernel contains the drivers an ordinary computer will
	    need.  &man.freebsd-update.8;, the &os; binary upgrade
	    tool, cannot upgrade custom kernels, another reason
	    to stick with the <literal>GENERIC</literal> 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="password-encryption">
	  <para>Should I use DES, Blowfish, or MD5 passwords and how do
	    I specify which form my users receive?</para>
	</question>

	<answer>
	  <para>&os;&nbsp;7 and 8 use MD5 password hashing by
	    default.  Recent versions
	    of &os; use <emphasis>SHA512</emphasis> by default.
	    These are
	    believed to be more secure than the traditional &unix;
	    password format, which used a scheme based on the
	    <emphasis>DES</emphasis> 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.  &os; also allows you to use the Blowfish
	    and MD5 password formats.  Which password
	    format to use for new passwords is controlled by the
	    <literal>passwd_format</literal> login capability in
	    <filename>/etc/login.conf</filename>, which takes values of
	    <literal>des</literal>, <literal>blf</literal> (if these are
	    available) or <literal>md5</literal>.  See the
	    &man.login.conf.5; manual page for more information about
	    login capabilities.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="memory-limits">
	  <para>What are the limits for memory?</para>
	</question>

	<answer>
	  <para>Memory limits depend on the platform used.  On a
	    standard &i386; install, the limit is 4&nbsp;GB but more
	    memory can be supported through &man.pae.4;.  See <link
	      linkend="memory-i386-over-4gb">instructions for using 4&nbsp;GB or more memory on &i386;</link>.</para>

	  <para>&os;/pc98 has a limit of 4&nbsp;GB memory, and PAE can
	    not be used with it.  Other architectures supported by &os;
	    have much higher theoretical limits on maximum memory (many
	    terabytes).</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ffs-limits">
	  <para>What are the limits for FFS file systems?</para>
	</question>

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

	  <para>The maximum size of a single FFS file is approximately
	    1&nbsp;G blocks, or 4&nbsp;TB with a block size of
	    4&nbsp;KB.</para>

	  <table>
	    <title>Maximum File Sizes</title>

	    <tgroup cols="3">
	      <thead>
		<row>
		  <entry>FS Block Size</entry>

		  <entry>Works</entry>

		  <entry>Should Work</entry>
		</row>
	      </thead>

	      <tbody>
		<row>
		  <entry>4&nbsp;KB</entry>

		  <entry>&gt;&nbsp;4&nbsp;GB</entry>

		  <entry>4&nbsp;TB&nbsp;-&nbsp;1</entry>
		</row>

		<row>
		  <entry>8&nbsp;KB</entry>

		  <entry>&gt;&nbsp;32&nbsp;GB</entry>

		  <entry>32&nbsp;TB&nbsp;-&nbsp;1</entry>
		</row>

		<row>
		  <entry>16&nbsp;KB</entry>

		  <entry>&gt;&nbsp;128&nbsp;GB</entry>

		  <entry>32&nbsp;TB&nbsp;-&nbsp;1</entry>
		</row>

		<row>
		  <entry>32&nbsp;KB</entry>

		  <entry>&gt;&nbsp;512&nbsp;GB</entry>

		  <entry>64&nbsp;TB&nbsp;-&nbsp;1</entry>
		</row>

		<row>
		  <entry>64&nbsp;KB</entry>

		  <entry>&gt;&nbsp;2048&nbsp;GB</entry>

		  <entry>128&nbsp;TB&nbsp;-&nbsp;1</entry>
		</row>
	      </tbody>
	    </tgroup>
	  </table>

	  <para>When the FS block size is 4&nbsp;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.
	    1024<superscript>3</superscript>&nbsp;+&nbsp;1024<superscript>2</superscript>&nbsp;+&nbsp;1024),
	    but everything is limited by a (wrong) limit of
	    1&nbsp;G&nbsp;-&nbsp;1 on FS block numbers.  The limit on FS
	    block numbers should be 2&nbsp;G&nbsp;-&nbsp;1.  There are
	    some bugs for FS block numbers near 2&nbsp;G&nbsp;-&nbsp;1,
	    but such block numbers are unreachable when the FS block
	    size is 4&nbsp;KB.</para>

	  <para>For block sizes of 8&nbsp;KB and larger, everything
	    should be limited by the 2&nbsp;G&nbsp;-&nbsp;1 limit on FS
	    block numbers, but is actually limited by the
	    1&nbsp;G&nbsp;-&nbsp;1 limit on FS block numbers.  Using the
	    correct limit of 2&nbsp;G&nbsp;-&nbsp;1 blocks does cause
	    problems.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="archsw-readin-failed-error">
	  <para>Why do I get an error message,
	    <errorname>readin failed</errorname> after compiling
	    and booting a new kernel?</para>
	</question>

	<answer>
	  <para>Because your world and kernel are out of sync.  This is
	    not supported.  Be sure you use <command>make <maketarget>buildworld</maketarget></command>
	    and <command>make <maketarget>buildkernel</maketarget></command>
	    to update your kernel.</para>

	  <para>You can boot by specifying the kernel directly at the
	    second stage, pressing any key when the <literal>|</literal>
	    shows up before loader is started.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="general-configuration-tool">
	  <para>Is there a tool to perform post-installation
	    configuration tasks?</para>
	</question>

	<answer>
	  <para>Yes, &rel.head.releng; users can set
	    <varname>WITH_BSDCONFIG</varname> in
	    <filename>/etc/src.conf</filename>.  Users of &rel.relx;
	    and higher may also install
	    <filename role="package">sysutils/bsdconfig</filename>.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="hardware">
    <title>Hardware Compatibility</title>

    <sect1 id="compatibility-general">
      <title>General</title>

      <qandaset>
	<qandaentry>
	  <question id="which-hardware-to-get">
	    <para>I want to get a piece of hardware for my &os; system.
	      Which model/brand/type is best?</para>
	  </question>

	  <answer>
	    <para>This is discussed continually on the &os; mailing
	      lists.  Since hardware changes so quickly, however, we
	      expect this.  We <emphasis>still</emphasis> strongly
	      recommend that you read through the Hardware&nbsp;Notes
	      for &os; <ulink
		url="&rel.current.hardware;">&rel.current;</ulink> or
	      <ulink
		url="&rel2.current.hardware;">&rel2.current;</ulink> and
	      search the mailing list <ulink
		url="http://www.FreeBSD.org/search/#mailinglists">archives</ulink>
	      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.</para>

	    <para>If you are looking for a laptop, check the &a.mobile;
	      archives.  Otherwise, you probably want the archives for
	      the &a.questions;, or possibly a specific mailing list for
	      a particular hardware type.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="memory-upper-limitation">
	    <para>Does &os; support more than 4&nbsp;GB of memory (RAM)?
	      More than 16&nbsp;GB?  More than 48&nbsp;GB?</para>
	  </question>

	  <answer>
	    <para>Yes.  &os; as an operating system generally supports
	      as much physical memory (RAM) as the platform it is running
	      on does.  Keep in mind that different platforms have
	      different limits for memory; for example &i386; without
	      <acronym>PAE</acronym> supports at most 4&nbsp;GB of
	      memory (and usually less than that because of PCI address
	      space) and &i386; with PAE supports at most 64&nbsp;GB
	      memory.  AMD64 platforms currently deployed support up to
	      1&nbsp;TB of physical memory.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="memory-i386-over-4gb">
	    <para>Why does &os; report less than 4&nbsp;GB memory when
	      installed on an &i386; machine?</para>
	  </question>

	  <answer>
	    <para>The total address space on &i386; machines is 32-bit,
	      meaning that at most 4&nbsp;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&nbsp;GB.  Usually, 3.2&nbsp;GB to 3.7&nbsp;GB is
	      the maximum usable physical memory in this
	      configuration.</para>

	    <para>To access more than 3.2&nbsp;GB to 3.7&nbsp;GB of
	      installed memory (meaning up to 4&nbsp;GB but also more than
	      4&nbsp;GB), a special tweak called <acronym>PAE</acronym>
	      must be used.  PAE stands for Physical Address Extension
	      and is a way for 32-bit x86 CPUs to address more than
	      4&nbsp;GB of memory.  It remaps the memory that would
	      otherwise be overlaid by address reservations for
	      hardware devices above the 4&nbsp;GB range and uses it as
	      additional physical memory (see &man.pae.4;).  Using PAE
	      has some drawbacks; this mode of memory access is a little
	      bit slower than the normal (without PAE) mode and loadable
	      modules (see &man.kld.4;) are not supported.  This means
	      all drivers must be compiled into the kernel.</para>

	    <para>The most common way to enable PAE is to build a new
	      kernel with the special ready-provided kernel configuration
	      file called <filename>PAE</filename>, 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:</para>

	    <programlisting>options       PAE</programlisting>

	    <para>PAE is not much used nowadays because most new x86
	      hardware also supports running in 64-bit mode, known as
	      AMD64 or &intel;&nbsp;64.  It has a much larger address
	      space and does not need such tweaks.  &os; supports AMD64
	      and it is recommended that this version of &os; be used
	      instead of the &i386; version if 4&nbsp;GB or more memory
	      is required.</para>
	  </answer>
	</qandaentry>
      </qandaset>
    </sect1>

    <sect1 id="compatibility-processors">
      <title>Architectures and Processors</title>

      <qandaset>
	<qandaentry>
	  <question id="architectures">
	    <para>Does &os; support architectures other than the
	      x86?</para>
	  </question>

	  <answer>
	    <para>Yes.  &os; divides support into multiple tiers.
	      Tier 1 architectures, such as i386 or amd64; are
	      fully supported.  Tiers 2 and 3 are supported on an
	      if-possible basis.  A full explanation of the tier
	      system is available in the
	      <ulink
		url="&url.articles.committers-guide;/archs.html">Committer's Guide.</ulink></para>

	    <para>A complete  list of supported architectures can be
	      found on the
	      <ulink
		url="http://www.FreeBSD.org/platforms/">platforms page.</ulink></para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="smp-support">
	    <para>Does &os; support Symmetric Multiprocessing
	      (SMP)?</para>
	  </question>

	  <answer>
	    <para>&os; supports symmetric multi-processor (SMP) on all
	      non-embedded platforms (e.g, &arch.i386;, &arch.amd64;,
	      etc.).  SMP is also
	      supported in arm and MIPS kernels, although some CPUs
	      may not support this.  &os;'s SMP implementation uses
	      fine-grained locking, and performance scales nearly
	      linearly with number of CPUs.</para>

	    <para>&man.smp.4; has more details.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="microcode">
	    <para>What is microcode?
	      How do I install &intel; CPU microcode updates?</para>
	  </question>

	  <answer>
	    <para>Microcode is a method of programmatically
	      implementating hardware level instructions.  This allows
	      for CPU bugs to be fixed without replacing the on board chip.</para>

	    <para>Install <filename role="package">sysutils/devcpu-data</filename>,
	      then add:</para>
	    <programlisting>microcode_update_enable="YES"</programlisting>

	    <para>to <filename>/etc/rc.conf</filename></para>
	  </answer>
	</qandaentry>
      </qandaset>
    </sect1>

    <sect1 id="compatibility-drives">
      <title>Hard Drives, Tape Drives, and CD and DVD Drives</title>

      <qandaset>
	<qandaentry>
	  <question id="supported-hard-drives">
	    <para>What kind of hard drives does &os; support?</para>
	  </question>

	  <answer>
	    <para>&os; supports EIDE, SATA, SCSI, and SAS drives (with a
	      compatible controller; see the next section), and all
	      drives using the original <quote>Western Digital</quote>
	      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.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="supported-scsi-controllers">
	    <para>Which SCSI or SAS controllers are supported?</para>
	  </question>

	  <answer>
	    <para>See the complete list in the Hardware Notes for &os;
	      <ulink url="&rel.current.hardware;">&rel.current;</ulink>
	      or <ulink
		url="&rel2.current.hardware;">&rel2.current;</ulink>.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="tape-support">
	    <para>What types of tape drives are supported?</para>
	  </question>

	  <answer>
	    <para>&os; supports all standard SCSI tape interfaces.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="tape-changer-support">
	    <para>Does &os; support tape changers?</para>
	  </question>

	  <answer>
	    <para>&os; supports SCSI changers using the &man.ch.4; device
	      and the &man.chio.1; command.  The details of how you
	      actually control the changer can be found in the
	      &man.chio.1; manual page.</para>

	    <para>If you are not using <application>AMANDA</application>
	      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.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="supported-cdrom-drives">
	    <para>Which CD-ROM drives are supported by &os;?</para>
	  </question>

	  <answer>
	    <para>Any SCSI drive connected to a supported controller is
	      supported.  Most ATAPI compatible IDE CD-ROMs are
	      supported.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="supported-cdrw-drives">
	    <para>Which CD-RW drives are supported by &os;?</para>
	  </question>

	  <answer>
	    <para>&os; supports any ATAPI-compatible IDE CD-R or CD-RW
	      drive.  See &man.burncd.8; for details.</para>

	    <para>&os; also supports any SCSI CD-R or CD-RW drives.
	      Install and use <command>cdrecord</command>
	      from the ports or packages system, and make sure that you
	      have the <devicename>pass</devicename> device compiled in
	      your kernel.</para>
	  </answer>
	</qandaentry>
      </qandaset>
    </sect1>

    <sect1 id="compatibility-kbd-mice">
      <title>Keyboards and Mice</title>

      <qandaset>
	<qandaentry>
	  <question id="moused">
	    <para>Is it possible to use a mouse in any way outside the X
	      Window system?</para>
	  </question>

	  <answer>
	    <para>If you are using the default console driver,
	      &man.syscons.4;, you can use a mouse pointer in text
	      consoles to cut &amp; paste text.  Run the mouse daemon,
	      &man.moused.8;, and turn on the mouse pointer in the
	      virtual console:</para>

	    <screen>&prompt.root; <userinput>moused -p /dev/<replaceable>xxxx</replaceable> -t <replaceable>yyyy</replaceable></userinput>
&prompt.root; <userinput>vidcontrol -m on</userinput></screen>

	    <para>Where <replaceable>xxxx</replaceable> is the mouse
	      device name and <replaceable>yyyy</replaceable> 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
	      <literal>auto</literal> protocol to invoke automatic
	      detection.  If automatic detection does not work, see the
	      &man.moused.8; manual page for a list of supported
	      protocol types.</para>

	    <para>If you have a PS/2 mouse, just add
	      <literal>moused_enable="YES"</literal> to
	      <filename>/etc/rc.conf</filename> 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
	      <literal>allscreens_flags="-m on"</literal> to
	      <filename>/etc/rc.conf</filename>.</para>

	    <para>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 <link
		linkend="x-and-moused">Why does my mouse not work with X?</link>
	      for more details on this issue.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="text-mode-cut-paste">
	    <para>How do I cut and paste text with a mouse in the text
	      console?</para>
	  </question>

	  <answer>
	    <para>It is not possible to remove data using the mouse.
	      However, it is possible to <quote>copy and
		paste</quote>.
	      Once you get the mouse daemon running (see the
	      <link linkend="moused">previous question</link>)
	      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 <quote>extend</quote> the selected region of
	      text.</para>

	    <para>If your mouse does not have a middle button, you may
	      wish to emulate one or remap buttons using mouse daemon
	      options.  See the &man.moused.8; manual page for
	      details.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="mouse-wheel-buttons">
	    <para>My mouse has a fancy wheel and buttons.  Can I use
	      them in &os;?</para>
	  </question>

	  <answer>
	    <para>The answer is, unfortunately, <quote>It
		depends</quote>.  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.</para>

	    <para>For the possible usage of wheels in the X Window
	      environment, refer to <link
		linkend="x-and-wheel">that section</link>.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="keyboard-delete-key">
	    <para>How do I use my delete key in <command>sh</command>
	      and <command>csh</command>?</para>
	  </question>

	  <answer>
	    <para>For the <application>Bourne Shell</application>, add
	      the following lines to your <filename>.shrc</filename>.  See
	      &man.sh.1; and &man.editrc.5;.</para>

	    <programlisting>bind ^? ed-delete-next-char # for console
bind ^[[3~ ed-delete-next-char # for xterm</programlisting>

	    <para>For the <application>C Shell</application>, add the
	      following lines to your <filename>.cshrc</filename>.  See
	      &man.csh.1;.</para>

	    <programlisting>bindkey ^? delete-char # for console
bindkey ^[[3~ delete-char # for xterm</programlisting>

	    <para>For more information, see <ulink
		url="http://www.ibb.net/~anne/keyboard.html">this page</ulink>.</para>
	  </answer>
	</qandaentry>
      </qandaset>
    </sect1>

    <sect1 id="compatibility-other">
      <title>Other Hardware</title>

      <qandaset>
	<qandaentry>
	  <question id="es1370-silent-pcm">
	    <para>Workarounds for no sound from my &man.pcm.4; sound
	      card?</para>
	  </question>

	  <answer>
	    <para>Some sound cards set their output volume to 0 at every
	      boot.  Run the following command every time the machine
	      boots:</para>

	    <screen>&prompt.root; <userinput>mixer pcm 100 vol 100 cd 100</userinput></screen>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="power-management-support">
	    <para>Does &os; support power management on my
	      laptop?</para>
	  </question>

	  <answer>
	    <para>&os; supports the <acronym>ACPI</acronym>
	      features found in modern hardware.  Further
	      information can be found in &man.acpi.4;.</para>
	  </answer>
	</qandaentry>
      </qandaset>
    </sect1>
  </chapter>

  <chapter id="troubleshoot">
    <title>Troubleshooting</title>

    <qandaset>
      <qandaentry>
	<question id="pae">
	  <para>Why is &os; finding the wrong amount of memory on &i386;
	    hardware?</para>
	</question>

	<answer>
	  <para>The most likely reason is the difference between
	    physical memory addresses and virtual addresses.</para>

	  <para>The convention for most PC hardware is to use the memory
	    area between 3.5&nbsp;GB and 4&nbsp;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.</para>

	  <para>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&nbsp;MB of RAM is entirely lost.</para>

	  <para>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.</para>

	  <para>On a 32-bit version of &os;, the memory appears
	    lost, since it will be remapped above 4&nbsp;GB, which a
	    32-bit kernel is unable to access.  In this case, the
	    solution is to build a PAE enabled kernel.  See <link
	      linkend="memory-limits">the entry on memory limits</link>
	    and <link linkend="memory-upper-limitation">about different
	    memory limits on different platforms</link> for more
	    information.</para>

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

      <qandaentry>
	<question id="signal11">
	  <para>Why do my programs occasionally die with
	    <errorname>Signal 11</errorname> errors?</para>
	</question>

	<answer>
	  <para>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.</para>

	  <para>These problems can usually be attributed to
	    either:</para>

	  <orderedlist>
	    <listitem>
	      <para>If the problem is occurring only in a specific
		application that you are developing yourself it is
		probably a bug in your code.</para>
	    </listitem>

	    <listitem>
	      <para>If it is a problem with part of the base &os;
		system, it may also be buggy code, but more often than not
		these problems are found and fixed long before us
		general FAQ readers get to use these bits of code (that
		is what -CURRENT is for).</para>
	    </listitem>
	  </orderedlist>

	  <para>In particular, a dead giveaway that this is
	    <emphasis>not</emphasis> a &os; 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.</para>

	  <para>For example, suppose you are running
	    <command>make <maketarget>buildworld</maketarget></command>,
	    and the compile fails while trying to compile
	    <filename>ls.c</filename> into <filename>ls.o</filename>.
	    If you then run
	    <command>make <maketarget>buildworld</maketarget></command>
	    again, and the compile fails in the same place then this is
	    a broken build &mdash; try updating your sources and try
	    again.  If the compile fails elsewhere then this is almost
	    certainly hardware.</para>

	  <para>What you should do:</para>

	  <para>In the first case you can use a debugger e.g.,
	    &man.gdb.1; to find the point in the program which is
	    attempting to access a bogus address and then fix it.</para>

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

	  <para>Common causes of this include:</para>

	  <orderedlist>
	    <listitem>
	      <para>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).</para>
	    </listitem>

	    <listitem>
	      <para>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.)</para>

	      <para>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.</para>
	    </listitem>

	    <listitem>
	      <para>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.</para>
	    </listitem>

	    <listitem>
	      <para>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 <quote>RAM Speed:
		Turbo</quote> 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!</para>
	    </listitem>

	    <listitem>
	      <para>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&nbsp;Watts try one rated at 300&nbsp;Watts).</para>
	    </listitem>
	  </orderedlist>

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

	  <para>Finally, if none of this has helped it is possible that
	    you have just found a bug in &os;, and you should follow the
	    instructions to send a problem report.</para>

	  <para>There is an extensive FAQ on this at <ulink
	      url="http://www.bitwizard.nl/sig11/">the SIG11 problem FAQ</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="trap-12-panic">
	  <para>My system crashes with either <errorname>Fatal trap 12:
	      page fault in kernel mode</errorname>, or
	    <errorname>panic:</errorname>, and spits out a bunch of
	    information.  What should I do?</para>
	</question>

	<answer>
	  <para>The &os; 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 <link
	      linkend="kernel-panic-troubleshooting">kernel panics</link>,
	    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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="proc-table-full">
	  <para>Why do I get the error <errorname>maxproc limit
	      exceeded by uid %i, please see tuning(7) and
	      login.conf(5)</errorname>?</para>
	</question>

	<answer>
	  <para>The &os; kernel will only allow a certain number of
	    processes to exist at one time.  The number is based on the
	    <varname>kern.maxusers</varname> &man.sysctl.8; variable.
	    <varname>kern.maxusers</varname> also affects various other
	    in-kernel limits, such as network buffers.
	    If your machine is heavily loaded, you probably
	    want to increase <varname>kern.maxusers</varname>.  This
	    will increase these other system limits in addition to the
	    maximum number of processes.</para>

	  <para>To adjust your <varname>kern.maxusers</varname> value,
	    see the <ulink
	      url="&url.books.handbook;/configtuning-kernel-limits.html#kern-maxfiles">File/Process Limits</ulink>
	    section of the Handbook.  (While that section refers to open
	    files, the same limits apply to processes.)</para>

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

      <qandaentry>
	<question id="mail-loopback">
	  <para>Why does <application>sendmail</application> give me an
	    error reading <errorname>mail loops back to
	      myself</errorname>?</para>
	</question>

	<answer>
	  <para>You can find a detailed answer for this question in the
	    <ulink
	      url="&url.books.handbook;/mail-trouble.html#q26.5.2.">Handbook</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="remote-fullscreen">
	  <para>Why do full screen applications on remote machines
	    misbehave?</para>
	</question>

	<answer>
	  <para>The remote machine may be setting your terminal type to
	    something other than the <literal>cons25</literal> terminal
	    type required by the &os; console.</para>

	  <para>There are a number of possible work-arounds for this
	    problem:</para>

	  <itemizedlist>
	    <listitem>
	      <para>After logging on to the remote machine, set your
		<envar>TERM</envar> shell variable to
		<literal>ansi</literal> or <literal>sco</literal> if
		the remote machine knows about these terminal
		types.</para>
	    </listitem>

	    <listitem>
	      <para>Use a VT100 emulator like
		<application>screen</application> at the &os; console.
		<application>screen</application> offers you the
		ability to run multiple concurrent sessions from one
		terminal, and is a neat program in its own right.
		Each <application>screen</application> window behaves
		like a VT100 terminal, so the <envar>TERM</envar>
		variable at the remote end should be set to
		<literal>vt100</literal>.</para>
	    </listitem>

	    <listitem>
	      <para>Install the <literal>cons25</literal> 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.</para>
	    </listitem>

	    <listitem>
	      <para>Fire up an X server at the &os; end and login to the
		remote machine using an X based terminal emulator such
		as <command>xterm</command> or <command>rxvt</command>.
		The <envar>TERM</envar> variable at the remote host
		should be set to <literal>xterm</literal> or
		<literal>vt100</literal>.</para>
	    </listitem>
	  </itemizedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="connection-delay">
	  <para>Why does it take so long to connect to my computer via
	    <command>ssh</command> or <command>telnet</command>?</para>
	</question>

	<answer>
	  <para>The symptom: there is a long delay between the time the
	    TCP connection is established and the time when the client
	    software asks for a password (or, in &man.telnet.1;'s case,
	    when a login prompt appears).</para>

	  <para>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
	    <application>Telnet</application> and
	    <application>SSH</application> servers that come with &os;,
	    do this to store the hostname
	    in a log file for future reference by the
	    administrator.</para>

	  <para>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.</para>

	  <para>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.</para>

	  <para>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 &man.hosts.5; and &man.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 &mdash; say, <hostid>www.yahoo.com</hostid>.  If it
	    does not work, that is your problem.</para>

	  <para>Following a fresh install of &os;, it is also possible
	    that domain and name server information is missing from
	    <filename>/etc/resolv.conf</filename>.  This will often
	    cause a delay in <application>SSH</application>, as the
	    option <literal>UseDNS</literal> is set to
	    <literal>yes</literal> by default in
	    <filename>/etc/ssh/sshd_config</filename>.
	    If this is causing the
	    problem, you will either need to fill in the missing
	    information in <filename>/etc/resolv.conf</filename> or set
	    <literal>UseDNS</literal> to <literal>no</literal> in
	    <filename>sshd_config</filename> as a temporary
	    workaround.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="file-table-full">
	  <para>Why does <errorname>file: table is full</errorname> show
	    up repeatedly in &man.dmesg.8;?</para>
	</question>

	<answer>
	  <para>This error message indicates you have exhausted the
	    number of available file descriptors on your system.  Please
	    see the <ulink
	      url="&url.books.handbook;/configtuning-kernel-limits.html#kern-maxfiles">kern.maxfiles</ulink>
	    section of the <ulink
	      url="&url.books.handbook;/configtuning-kernel-limits.html">Tuning Kernel Limits</ulink>
	    section of the Handbook for a discussion and
	    solution.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="computer-clock-skew">
	  <para>Why does the clock on my computer keep incorrect time?</para>
	</question>

	<answer>
	  <para>Your computer has two or more clocks, and &os; has
	    chosen to use the wrong one.</para>

	  <para>Run &man.dmesg.8;, and check for lines that contain
	    <literal>Timecounter</literal>.  The one with the highest
	    quality value that &os; chose.</para>

	  <screen>&prompt.root; <userinput>dmesg | grep Timecounter</userinput>
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</screen>

	  <para>You can confirm this by checking the
	    <varname>kern.timecounter.hardware</varname>
	    &man.sysctl.3;.</para>

	  <screen>&prompt.root; <userinput>sysctl kern.timecounter.hardware</userinput>
kern.timecounter.hardware: ACPI-fast</screen>

	  <para>It may be a broken ACPI timer.  The simplest solution is
	    to disable the ACPI timer in
	    <filename>/boot/loader.conf</filename>:</para>

	  <programlisting>debug.acpi.disabled="timer"</programlisting>

	  <para>Or the BIOS may modify the TSC clock&mdash;perhaps to
	    change the speed of the processor when running from batteries,
	    or going into a power saving mode, but &os; is unaware of
	    these adjustments, and appears to gain or lose time.</para>

	  <para>In this example, the <literal>i8254</literal> clock is
	    also available, and can be selected by writing its name to the
	    <varname>kern.timecounter.hardware</varname>
	    &man.sysctl.3;.</para>

	  <screen>&prompt.root; <userinput>sysctl kern.timecounter.hardware=i8254</userinput>
kern.timecounter.hardware: TSC -&gt; i8254</screen>

	  <para>Your computer should now start keeping more accurate
	    time.</para>

	  <para>To have this change automatically run at boot time, add
	    the following line to
	    <filename>/etc/sysctl.conf</filename>:</para>

	  <programlisting>kern.timecounter.hardware=i8254</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="indefinite-wait-buffer">
	  <para>What does the error <errorname>swap_pager: indefinite
	      wait buffer:</errorname> mean?</para>
	</question>

	<answer>
	  <para>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
	    <filename>/var/log/messages</filename> and in the output of
	    <command>dmesg</command>.  Otherwise, check your cables and
	    connections.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="lock-order-reversal">
	  <para>What is a <errorname>lock order
	      reversal</errorname>?</para>
	</question>

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

	  <para>A run-time lock diagnostic system called &man.witness.4;,
	    enabled in &os.current; and disabled by default for stable
	    branches and releases, detects the potential for deadlocks due to
	    locking errors, including errors caused by obtaining multiple
	    resource locks with a different order from different parts of the
	    kernel.  The &man.witness.4; framework tries to detect this
	    problem as it happens, and reports it by printing a message to the
	    system console about a <errorname>lock order reversal</errorname>
	    (often referred to also as <acronym>LOR</acronym>).</para>

	  <para>It is possible to get false positives, as &man.witness.4;
	    is conservative.  A true positive report <emphasis>does
	      not</emphasis> mean that a system is dead-locked; instead
	    it should be understood as a warning of the form <quote>if
	      you were unlucky, a deadlock would have happened
	      here</quote>.</para>

	  <note>
	    <para>Problematic <acronym>LOR</acronym>s tend to get fixed
	      quickly, so check &a.current.url; before posting to the
	      mailing lists.</para>
	  </note>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="called-with-non-sleepable-locks-held">
	  <para>What does <errorname>Called ...  with the following
	      non-sleepable locks held</errorname> mean?</para>
	</question>

	<answer>
	  <para>This means that a function that may sleep was called
	    while a mutex (or other unsleepable) lock was held.</para>

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

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

	  <para>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.</para>

	  <para>For additional information about locking in &os; see
	    &man.locking.9;.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="touch-not-found">
	  <para>Why does
	    <maketarget>buildworld</maketarget>/<maketarget>installworld</maketarget>
	    die with the message <errorname>touch: not
	      found</errorname>?</para>
	</question>

	<answer>
	  <para>This error does not mean that the &man.touch.1; utility
	    is missing.  The error is instead probably due to the dates
	    of the files being set sometime in the future.  If your
	    CMOS-clock is set to local time you need to run the command
	    <command>adjkerntz&nbsp;-i</command> to adjust the kernel
	    clock when booting into single user mode.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="applications">
    <title>User Applications</title>

    <qandaset>
      <qandaentry>
	<question id="user-apps">
	  <para>So, where are all the user applications?</para>
	</question>

	<answer>
	  <para>Please take a look at <ulink
	      url="&url.base;/ports/index.html">the ports page</ulink>
	    for info on software packages ported to &os;.  The list
	    currently tops &os.numports; and is growing daily, so come
	    back to check often or subscribe to the &a.announce; for
	    periodic updates on new entries.</para>

	  <para>Most ports should work on the
	    &rel2.relx;, and &rel.relx; branches.
	    Each time a &os;
	    release is made, a snapshot of the ports tree at the time of
	    release in also included in the <filename class="directory">ports/</filename>
	    directory.</para>

	  <para>We also support the concept of a <quote>package</quote>,
	    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.</para>

	  <para>Use
	    &man.pkg.add.1; on the specific package files
	    you are interested in installing.  Package files can usually
	    be identified by their <filename>.tbz</filename> suffix and
	    CD-ROM distribution people will have a
	    <filename class="directory">packages/All</filename> directory on their CD
	    which contains such files.  They can also be downloaded over
	    the net for various versions of &os; at the following
	    locations:</para>

	  <variablelist>
	    <varlistentry>
	      <term>for &rel2.relx;&nbsp;-RELEASE/&rel2.stable;</term>

	      <listitem>
		<para><ulink
		    url="ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel2.packages;/">ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel2.packages;</ulink></para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>for &rel.relx;&nbsp;-RELEASE/&rel.stable;</term>

	      <listitem>
		<para><ulink
		    url="ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel.packages;/">ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel.packages;</ulink></para>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>or your nearest local mirror site.</para>

	  <para>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 <ulink
	      url="ftp://ftp.FreeBSD.org/pub/FreeBSD/">ftp.FreeBSD.org</ulink>
	    master site.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="how-do-download-ports-tree">
	  <para>How do I download the Ports tree? Should I be using
	    SVN?</para>
	</question>

	<answer>
	  <para>Any of the methods listed here work:</para>

	  <itemizedlist>
	    <listitem>
	      <para>Use portsnap for most use cases.</para>
	    </listitem>
	    <listitem>
	      <para>Use SVN directly if you need custom patches
		to the ports tree.</para>
	    </listitem>
	    <listitem>
	      <para>Use CTM if you prefer getting patches
		by email (this is a rarer use case).</para>
	    </listitem>
	  </itemizedlist>

	  <para>Any other method should be considered a
	    legacy method.  If you do not already use them,
	    do not start.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="java">
	  <para>Does &os; support &java;?</para>
	</question>

	<answer>
	  <para>Yes.  Please see <ulink
	      url="&url.base;/java/index.html">http://www.FreeBSD.org/java/</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ports-4x">
	  <para>Why can I not build this port on my
	    &rel2.relx;&nbsp;-, or
	    &rel.relx;&nbsp;-STABLE machine?</para>
	</question>

	<answer>
	  <para>If you are running a &os; version that lags
	    significantly behind <emphasis>-CURRENT</emphasis> or
	    <emphasis>-STABLE</emphasis>, you may need to update your
	    Ports Collection; see the <ulink
	      url="&url.books.porters-handbook;/keeping-up.html">Keeping Up</ulink>
	    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
	    <emphasis>-CURRENT</emphasis> but which broke the port for
	    <emphasis>-STABLE</emphasis>.  Please submit a bug report on
	    this with the &man.send-pr.1; command, since the Ports
	    Collection is supposed to work for both the
	    <emphasis>-CURRENT</emphasis> and
	    <emphasis>-STABLE</emphasis> branches.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="make-index">
	  <para>I just tried to build <filename>INDEX</filename> using
	    <command>make <maketarget>index</maketarget></command>, and
	    it failed.  Why?</para>
	</question>

	<answer>
	  <para>First, always make sure that you have a complete
	    up-to-date Ports Collection.  Errors that affect building
	    <filename>INDEX</filename> from an up-to-date copy of the
	    Ports Collection are high-visibility and are thus almost
	    always fixed immediately.</para>

	  <para>There are rare cases where <filename>INDEX</filename>
	    will not build due to odd cases involving
	    <makevar>WITH_<replaceable>*</replaceable></makevar> or
	    <makevar>WITHOUT_<replaceable>*</replaceable></makevar>
	    variables being set in <filename>make.conf</filename>.  If
	    you suspect that this is the case, please try to make
	    <filename>INDEX</filename> with those make variables turned
	    off before reporting it to &a.ports;.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ports-update">
	  <para>I updated the sources, now how do I update my installed
	    ports?</para>
	</question>

	<answer>
	  <para>&os; 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 <ulink
	      url="&url.books.handbook;/ports-using.html">Upgrading Ports</ulink>
	    section in the &os; Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ports-major-upgrade">
	  <para>Do I need to recompile every port each time I perform a
	    major version update?</para>
	</question>

	<answer>
	  <para>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.</para>

	  <para>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.</para>

	  <para>For more information, see <ulink
	      url="&url.books.handbook;/updating-upgrading-freebsdupdate.html#freebsdupdate-upgrade">the section on upgrades</ulink>
	    in the &os; Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ports-minor-upgrade">
	  <para>Do I need to recompile every port each time I perform a
	    minor version update?</para>
	</question>

	<answer>
	  <para>In general, no.  &os; developers do their utmost to
	    guarantee binary compatibility across all releases with the
	    same major version number.  Any exceptions will be
	    documented in the Release Notes, and advice given there
	    should be followed.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="minimal-sh">
	  <para>Why is <command>/bin/sh</command> so minimal?  Why
	    does &os; not use <command>bash</command> or another
	    shell?</para>
	</question>

	<answer>
	  <para>Many people need to write shell scripts which will be
	    portable across many systems.  That is why &posix;
	    specifies the shell and utility commands in great detail.
	    Most scripts are written in Bourne shell (&man.sh.1;), and
	    because several important programming interfaces
	    (&man.make.1;, &man.system.3;, &man.popen.3;, and
	    analogues in higher-level scripting languages like Perl
	    and Tcl) are specified to use the Bourne shell to
	    interpret commands.  Because the Bourne shell is so often
	    and widely used, it is important for it to be quick to
	    start, be deterministic in its behavior, and have a small
	    memory footprint.</para>

	  <para>The existing implementation is our best effort at
	    meeting as many of these requirements simultaneously as we
	    can.  To keep <command>/bin/sh</command> small,
	    we have not provided many of the convenience features that
	    other shells have.  That is why other more
	    featureful shells like
	    <command>bash</command>, <command>scsh</command>,
	    &man.tcsh.1;, and <command>zsh</command> are available.
	    (You can
	    compare for yourself the memory utilization of all these
	    shells by looking at the <quote>VSZ</quote> and
	    <quote>RSS</quote> columns in a <command>ps
	      <option>-u</option></command> listing.)</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="midi-sound-files">
	  <para>How do I create audio CDs from my MIDI files?</para>
	</question>

	<answer>
	  <para>To create audio CDs from MIDI files, first install
	    <filename role="package">audio/timidity++</filename> from
	    ports then install manually the GUS patches set by Eric A.
	    Welsh, available at <ulink
	      url="http://alleg.sourceforge.net/digmid.html"></ulink>.
	    After <application>TiMidity++</application> has been installed
	    properly, MIDI files may be converted to WAV files with the
	    following command line:</para>

	  <screen>&prompt.user; <userinput>timidity -Ow -s 44100 -o <replaceable>/tmp/juke/01.wav</replaceable> <replaceable>01.mid</replaceable></userinput></screen>

	  <para>The WAV files can then be converted to other formats or
	    burned onto audio CDs, as described in the <ulink
	      url="&url.books.handbook;/creating-cds.html">&os; Handbook</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="officesuite">
	  <para>Where can I get an Office Suite for &os;?</para>
	</question>

	<answer>
	  <para>The open-source <application><ulink
		url="http://www.openoffice.org">Apache OpenOffice</ulink></application>
	    and <application><ulink
		url="http://www.libreoffice.org">LibreOffice</ulink></application>
	    office suites work natively on &os;.</para>

	  <para>&os; also includes a variety of text editors,
	    spreadsheets, and drawing programs in the Ports
	    Collection.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="convert-back-from-pkgng">
	  <para>How can I convert from pkgng to the old package
	    tools?</para>
	</question>

	<answer>
	  <para>Short answer: it is not possible.</para>

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

  <chapter id="kernelconfig">
    <title>Kernel Configuration</title>

    <qandaset>
      <qandaentry>
	<question id="make-kernel">
	  <para>I would like to customize my kernel.  Is it
	    difficult?</para>
	</question>

	<answer>
	  <para>Not at all!  Check out the <ulink
	      url="&url.books.handbook;/kernelconfig.html">kernel config section of the Handbook</ulink>.</para>

	  <note>
	    <para>The new <filename>kernel</filename> will be installed
	      to the <filename class="directory">/boot/kernel</filename> directory along
	      with its modules, while the old kernel and its modules
	      will be moved to the <filename class="directory">/boot/kernel.old</filename>
	      directory, so if you make a mistake the next time you play
	      with your configuration you can boot the previous version
	      of your kernel.</para>
	  </note>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="why-kernel-big">
	  <para>Why is my kernel so big?</para>
	</question>

	<answer>
	  <para><literal>GENERIC</literal> kernels shipped with &os;
	    and later are compiled in <emphasis>debug mode</emphasis>.
	    Kernels built in debug mode
	    contain many symbols in separate files that are used for
	    debugging, thus greatly increasing the size of
	    <filename class="directory">/boot/kernel/</filename>.
	    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.</para>

	  <para>However, if you are running low on disk space, there
	    are different options to reduce the size of <filename
	      class="directory">/boot/kernel/</filename>.</para>

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

	  <programlisting>WITHOUT_KERNEL_SYMBOLS=yes</programlisting>

	  <para>For more information see &man.src.conf.5;.</para>

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

	  <itemizedlist>
	    <listitem>
	      <para>You do not have a line in your kernel configuration
		file that reads:</para>

	      <programlisting>makeoptions DEBUG=-g</programlisting>
	    </listitem>

	    <listitem>
	      <para>You are not running &man.config.8; with
		<option>-g</option>.</para>
	    </listitem>
	  </itemizedlist>

	  <para>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.</para>

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

	  <programlisting>MODULES_OVERRIDE= <replaceable>accf_http ipfw</replaceable></programlisting>

	  <para>Replace <emphasis>accf_httpd ipfw</emphasis> 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
	    <filename>/usr/share/examples/etc/make.conf</filename>.</para>

	  <para>You can also remove unneeded devices from your kernel
	    to further reduce the size.  See
	    <xref linkend="make-kernel"/> for more information.</para>

	  <para>To put any of these options into effect you will have
	    to <ulink url="&url.books.handbook;/kernelconfig-building.html">build and install</ulink>
	    your new kernel.</para>

	  <para>Most kernels (<filename>/boot/kernel/kernel</filename>)
	    tend to be around 12&nbsp;MB to 16&nbsp;MB.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="generic-kernel-build-failure">
	  <para>Why does every kernel I try to build fail to compile,
	    even <filename>GENERIC</filename>?</para>
	</question>

	<answer>
	  <para>There are a number of possible causes for this problem.
	    They are, in no particular order:</para>

	  <itemizedlist>
	    <listitem>
	      <para>You are not using the
		<command>make <maketarget>buildkernel</maketarget></command> and
		<command>make <maketarget>installkernel</maketarget></command>
		targets, and your source tree is different from the one
		used to build the currently running system (e.g., you
		are compiling &rel.current;-RELEASE on a
		&rel2.current;-RELEASE system).  If you are attempting
		an upgrade, please read
		<filename>/usr/src/UPDATING</filename>, paying
		particular attention to the <quote>COMMON ITEMS</quote>
		section at the end.</para>
	    </listitem>

	    <listitem>
	      <para>You are using the
		<command>make <maketarget>buildkernel</maketarget></command>
		and
		<command>make <maketarget>installkernel</maketarget></command>
		targets, but you failed to assert the completion of the
		<command>make <maketarget>buildworld</maketarget></command>
		target.  The
		<command>make <maketarget>buildkernel</maketarget></command>
		target relies on files generated by the
		<command>make <maketarget>buildworld</maketarget></command>
		target to complete its job correctly.</para>
	    </listitem>

	    <listitem>
	      <para>Even if you are trying to build <link
		  linkend="stable">&os;-STABLE</link>, 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 <link linkend="stable">&os;-STABLE</link>
		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.</para>
	    </listitem>
	  </itemizedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="scheduler-in-use">
	  <para>How can I verify which scheduler is in use on a running
	    system?</para>
	</question>

	<answer>
	  <para>The name of the scheduler currently being used is
	    directly available as the value of the
	    <varname>kern.sched.name</varname> sysctl:</para>

	  <screen>&prompt.user; sysctl <replaceable>kern.sched.name</replaceable>
kern.sched.name: ULE</screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="scheduler-kern-quantum">
	  <para>What is <varname>kern.sched.quantum</varname>?</para>
	</question>

	<answer>
	  <para><varname>kern.sched.quantum</varname> is the maximum
	    number of ticks a process can run without being preempted
	    in the 4BSD scheduler.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="disks">
    <title>Disks, File Systems, and Boot Loaders</title>

    <qandaset>
      <qandaentry>
	<question id="adding-disks">
	  <para>How can I add my new hard disk to my &os; system?</para>
	</question>

	<answer>
	  <para>See the <ulink
	      url="&url.books.handbook;/disks-adding.html">Adding Disks</ulink>
	    section in the &os; Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="new-huge-disk">
	  <para>How do I move my system over to my huge new disk?</para>
	</question>

	<answer>
	  <para>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 <emphasis>-STABLE</emphasis> for more
	    than one release, or have updated a release instead of
	    installing a new one.  You can install booteasy on both
	    disks with &man.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.</para>

	  <para>Alternatively, partition and label the new disk with either
	    &man.sade.8; or &man.gpart.8;.  If the disks are MBR-formatted,
	    you can also install booteasy on both disks with
	    &man.boot0cfg.8;, so that you can dual boot to the old or
	    new system after the copying is done.</para>

	  <para>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
	    <filename class="directory">/dev</filename>), flags, and links tend to screw
	    that up.  You need to use tools that understand these
	    things, which means &man.dump.8;.  Although it is suggested
	    that you move the data in single user mode, it is not
	    required.</para>

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

	  <procedure>
	    <step>
	      <para><command>newfs</command> the new partition.</para>
	    </step>

	    <step>
	      <para><command>mount</command> it on a temporary mount
		point.</para>
	    </step>

	    <step>
	      <para><command>cd</command> to that directory.</para>
	    </step>

	    <step>
	      <para><command>dump</command> the old partition, piping
		output to the new one.</para>
	    </step>
	  </procedure>

	  <para>For example, if you are going to move root to
	    <devicename>/dev/<replaceable>ada1s1a</replaceable></devicename>,
	    with <filename class="directory"><replaceable>/mnt</replaceable></filename> as
	    the temporary mount point, it is:</para>

	  <screen>&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1a</replaceable></userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1a</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>cd <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>dump 0af - / | restore rf -</userinput></screen>

	  <para>Rearranging your partitions with <command>dump</command>
	    takes a bit more work.  To merge a partition like
	    <filename class="directory">/var</filename> 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:</para>

	  <screen>&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1a</replaceable></userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1a</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>cd <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>dump 0af - / | restore rf -</userinput>
&prompt.root; <userinput>cd var</userinput>
&prompt.root; <userinput>dump 0af - /var | restore rf -</userinput></screen>

	  <para>To split a directory from its parent, say putting
	    <filename class="directory">/var</filename> 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:</para>

	  <screen>&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1a</replaceable></userinput>
&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1d</replaceable></userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1a</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>mkdir <replaceable>/mnt</replaceable>/var</userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1d</replaceable> <replaceable>/mnt</replaceable>/var</userinput>
&prompt.root; <userinput>cd <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>dump 0af - / | restore rf -</userinput></screen>

	  <para>You might prefer &man.cpio.1;, &man.pax.1;, &man.tar.1;
	    to &man.dump.8; for user data.  At the time of this writing,
	    these are known to lose file flag information, so use them
	    with caution.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="safe-softupdates">
	  <para>Which partitions can safely use Soft Updates?  I have
	    heard that Soft Updates on <filename class="directory">/</filename> can cause
	    problems.  What about Journaled Soft Updates?</para>
	</question>

	<answer>
	  <para>Short answer: you can usually use Soft Updates safely on
	    all partitions.</para>

	  <para>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.</para>

	  <para>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 &os; file system, or
	    both.</para>

	  <para>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.</para>

	  <para>These issues affect all partitions using Soft Updates.
	    So, what does this mean for the root partition?</para>

	  <para>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!</para>

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

	  <para>Finally, &man.dump.8; does not work in live mode (-L)
	    on a filesystem, with Journaled Soft Updates
	    (<acronym>SU+J</acronym>).</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mount-foreign-fs">
	  <para>Can I mount other foreign file systems under
	    &os;?</para>
	</question>

	<answer>
	  <para>&os; supports a variety of other file systems.</para>

	  <variablelist>
	    <varlistentry>
	      <term>UFS</term>

	      <listitem>
		<para>UFS CD-ROMs can be mounted directly on &os;.
		  Mounting disk partitions from Digital UNIX and other
		  systems that support UFS may be more complex,
		  depending on the details of the disk partitioning for
		  the operating system in question.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>ext2/ext3</term>

	      <listitem>
		<para>&os; supports <literal>ext2fs</literal> and
		  <literal>ext3fs</literal> partitions.  See
		  &man.ext2fs.5; for more information.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>NTFS</term>

	      <listitem>
		<para>FUSE based NTFS support is available as a port
		  (<filename role="package">sysutils/fusefs-ntfs</filename>).
		  For more information see <ulink
		    url="http://www.tuxera.com/community/ntfs-3g-manual/"><application>ntfs-3g</application></ulink>.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>FAT</term>

	      <listitem>
		<para>&os; includes a read-write FAT driver.  For more
		  information, see &man.mount.msdosfs.8;.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term>ZFS</term>

	      <listitem>
		<para>&os; includes a port of
		  &sun;'s ZFS driver.  The current recommendation is to
		  use it only on &arch.amd64; platforms with sufficient
		  memory.  For more information, see &man.zfs.8;.</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>&os; also supports network file systems such as NFS (see
	    &man.mount.nfs.8;), NetWare (see &man.mount.nwfs.8;), and
	    Microsoft-style SMB file systems (see &man.mount.smbfs.8;).
	    You can find ports based on FUSE (<filename
	      role="package">sysutils/fusefs-kmod</filename>) for many
	    other file systems.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mount-dos">
	  <para>How do I mount a secondary DOS partition?</para>
	</question>

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

	  <screen>&prompt.root; <userinput>mount -t msdosfs /dev/da1s5 /dos/e</userinput></screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="crypto-file-system">
	  <para>Is there a cryptographic file system for &os;?</para>
	</question>

	<answer>
	  <para>Yes.  You can use either &man.gbde.8; or &man.geli.8;,
	    see the <ulink
	      url="&url.books.handbook;/disks-encrypting.html">Encrypting Disk Partitions</ulink>
	    section of the &os; Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="nt-bootloader">
	  <para>How can I use the &windowsnt; loader to boot
	    &os;?</para>
	</question>

	<answer>
	  <para>The general idea is that you copy the first sector of
	    your native root &os; partition into a file in the
	    DOS/&windowsnt; partition.  Assuming you name that file
	    something like <filename>c:\bootsect.bsd</filename>
	    (inspired by <filename>c:\bootsect.dos</filename>), you can
	    then edit <filename>c:\boot.ini</filename> to come
	    up with something like this:</para>

	  <programlisting>[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="&os;"
C:\="DOS"</programlisting>

	  <para>If &os; is installed on the same disk as the &windowsnt;
	    boot partition simply copy <filename>/boot/boot1</filename> to
	    <filename>C:\BOOTSECT.BSD</filename>.  However, if &os; is
	    installed on a different disk
	    <filename>/boot/boot1</filename> will not work,
	    <filename>/boot/boot0</filename> is needed.</para>

	  <para><filename>/boot/boot0</filename> needs to be installed
	    using &man.sysinstall.8; by selecting the &os; boot manager
	    on the screen which asks if you wish to use a boot manager.
	    This is because <filename>/boot/boot0</filename> has the
	    partition table area filled with NULL characters but
	    &man.sysinstall.8; copies the partition table before copying
	    <filename>/boot/boot0</filename> to the MBR.</para>

	  <warning>
	    <para><emphasis>Do not simply copy
		<filename>/boot/boot0</filename> instead of
		<filename>/boot/boot1</filename>; you will overwrite
		your partition table and render your computer
		un-bootable!</emphasis></para>
	  </warning>

	  <para>When the &os; 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
	    <filename>/boot/boot0</filename> to
	    <filename>C:\BOOTSECT.BSD</filename> then it writes an empty
	    partition table, with the active flag set on one entry, to
	    the MBR.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="lilo-bootloader">
	  <para>How do I boot &os; and &linux; from LILO?</para>
	</question>

	<answer>
	  <para>If you have &os; and &linux; on the same disk, just
	    follow LILO's installation instructions for booting a
	    non-&linux; operating system.  Very briefly, these
	    are:</para>

	  <para>Boot &linux;, and add the following lines to
	    <filename>/etc/lilo.conf</filename>:</para>

	  <programlisting>other=/dev/hda2
        table=/dev/hda
        label=&os;</programlisting>

	  <para>(the above assumes that your &os; slice is known to
	    &linux; as <devicename>/dev/hda2</devicename>; tailor to
	    suit your setup).  Then, run <command>lilo</command> as
	    <username>root</username> and you should be done.</para>

	  <para>If &os; resides on another disk, you need to add
	    <literal>loader=/boot/chain.b</literal> to the LILO entry.
	    For example:</para>

	  <programlisting>other=/dev/dab4
        table=/dev/dab
        loader=/boot/chain.b
        label=&os;</programlisting>

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

	  <screen>Boot: <userinput>1:da(0,a)/boot/kernel/kernel</userinput></screen>

	  <para>You can configure &man.boot.8; to automatically do this
	    for you at boot time.</para>

	  <para>The <ulink
	      url="http://tldp.org/HOWTO/Linux+FreeBSD.html">&linux;+&os; mini-HOWTO</ulink>
	    is a good reference for &os; and &linux; interoperability
	    issues.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="grub-loader">
	  <para>How do I boot &os; and &linux; using GRUB?</para>
	</question>

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

	  <programlisting>title &os; 6.1
	root <replaceable>(hd0,a)</replaceable>
	kernel /boot/loader</programlisting>

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

      <qandaentry>
	<question id="booteasy-loader">
	  <para>How do I boot &os; and &linux; using
	    <application>BootEasy?</application></para>
	</question>

	<answer>
	  <para>Install LILO at the start of your &linux; boot partition
	    instead of in the Master Boot Record.  You can then boot
	    LILO from <application>BootEasy</application>.</para>

	  <para>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).</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="changing-bootprompt">
	  <para>How do I change the boot prompt from
	    <literal>???</literal> to something more meaningful?</para>
	</question>

	<answer>
	  <para>You can not do that with the standard boot manager
	    without rewriting it.  There are a number of other boot
	    managers in the <filename class="directory">sysutils</filename> ports category
	    that provide this functionality.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="removable-drives">
	  <para>I have a new removable drive, how do I use it?</para>
	</question>

	<answer>
	  <para>If the drive already has a
	    file system on it, you can use a command like this:</para>

	  <screen>&prompt.root; <userinput>mount -t msdosfs /dev/da0s1 /mnt</userinput></screen>

	  <para>If the drive will only be used with &os;
	    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.</para>

	  <screen>&prompt.root; <userinput>dd if=/dev/zero of=/dev/da0 count=2</userinput>
&prompt.root; <userinput>gpart create -s GPT /dev/da0</userinput>
&prompt.root; <userinput>gpart add -t freebsd-ufs /dev/da0</userinput></screen>

	  <para>Finally, create a new file system:</para>

	  <screen>&prompt.root; <userinput>newfs /dev/da0p1</userinput></screen>

	  <para>and mount it:</para>

	  <screen>&prompt.root; <userinput>mount /dev/da0s1 /mnt</userinput></screen>

	  <para>It is a good idea to add a line
	    to <filename>/etc/fstab</filename> (see &man.fstab.5;) so
	    you can just type <command>mount /mnt</command> in the
	    future:</para>

	  <programlisting>/dev/da0p1 /mnt ufs rw,noauto 0 0</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mount-cd-superblock">
	  <para>Why do I get <errorname>Incorrect super
	      block</errorname> when mounting a CD-ROM?</para>
	</question>

	<answer>
	  <para>You have to tell &man.mount.8; the type of the device
	    that you want to mount.  This is described in the <ulink
	      url="&url.books.handbook;/creating-cds.html"> Handbook section on optical media</ulink>,
	    specifically the section <ulink
	      url="&url.books.handbook;/creating-cds.html#mounting-cd">Using Data CDs</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="cdrom-not-configured">
	  <para>Why do I get <errorname>Device not
	      configured</errorname> when mounting a CD-ROM?</para>
	</question>

	<answer>
	  <para>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 <ulink
	      url="&url.books.handbook;/creating-cds.html#mounting-cd">Using Data CDs</ulink>
	    section of the Handbook for a detailed discussion of this
	    issue.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="cdrom-unicode-filenames">
	  <para>Why do all non-English characters in filenames show up
	    as <quote>?</quote> on my CDs when mounted in &os;?</para>
	</question>

	<answer>
	  <para>Your CD-ROM probably uses the <quote>Joliet</quote>
	    extension for storing information about files and
	    directories.  This is discussed in the Handbook chapter on
	    <ulink
	      url="&url.books.handbook;/creating-cds.html">creating and using CD-ROMs</ulink>,
	    specifically the section on <ulink
	      url="&url.books.handbook;/creating-cds.html#mounting-cd">Using Data CD-ROMs</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="burncd-isofs">
	  <para>I burned a CD under &os; and now I can not read it under
	    any other operating system.  Why?</para>
	</question>

	<answer>
	  <para>You most likely burned a raw file to your CD, rather
	    than creating an ISO&nbsp;9660 file system.  Take a look at
	    the <ulink
	      url="&url.books.handbook;/creating-cds.html">Handbook chapter on creating CD-ROMs</ulink>,
	    particularly the section on <ulink
	      url="&url.books.handbook;/creating-cds.html#rawdata-cd">burning raw data CDs</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="copy-cd">
	  <para>How can I create an image of a data CD?</para>
	</question>

	<answer>
	  <para>This is discussed in the Handbook section on <ulink
	      url="&url.books.handbook;/creating-cds.html#imaging-cd">duplicating data CDs</ulink>.
	    For more on working with CD-ROMs, see the <ulink
	      url="&url.books.handbook;/creating-cds.html">Creating CDs Section</ulink>
	    in the Storage chapter in the Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mount-audio-CD">
	  <para>Why can I not <command>mount</command> an audio
	    CD?</para>
	</question>

	<answer>
	  <para>If you try to mount an audio CD, you will get an error
	    like <errorname>cd9660: /dev/acd0c: Invalid
	    argument</errorname>.  This is because
	    <command>mount</command> 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 <filename
	      role="package">audio/xmcd</filename> port.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="multi-session-CD">
	  <para>How do I <command>mount</command> a multi-session
	    CD?</para>
	</question>

	<answer>
	  <para>By default, &man.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 <option>-s</option>
	    command line argument.  Please see &man.mount.cd9660.8; for
	    specific examples.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="user-floppymount">
	  <para>How do I let ordinary users mount CD-ROMs, DVDs,
	    USB drives, and other removable media?</para>
	</question>

	<answer>
	  <para>As <username>root</username> set the sysctl variable
	    <varname>vfs.usermount</varname> to
	    <literal>1</literal>.</para>

	  <screen>&prompt.root; <userinput>sysctl vfs.usermount=1</userinput></screen>

	  <para>To make this persist across reboots, add the line
	    <literal><varname>vfs.usermount</varname>=1</literal> to
	    <filename>/etc/sysctl.conf</filename> so that
	    it is reset at system boot time.</para>

	  <para>Users can only mount devices they have read
	    permissions to.  To allow users to mount a device
	    permissions must be set in
	    <filename>/etc/devfs.conf</filename>.</para>

	  <para>For example, to allow users to mount the first USB
	    drive add:</para>

	  <programlisting># Allow all users to mount a USB drive.
	    own       /dev/da0       root:operator
	    perm      /dev/da00       0666</programlisting>

	  <para>All users can now mount devices they could read
	    onto a directory that they own:</para>

	  <screen>&prompt.user; <userinput>mkdir <replaceable>~/my-mount-point</replaceable></userinput>
&prompt.user; <userinput>mount -t msdosfs /dev/da0<replaceable>~/my-mount-point</replaceable></userinput></screen>

	  <para>Unmounting the device is simple:</para>

	  <screen>&prompt.user; <userinput>umount <replaceable>~/my-mount-point</replaceable></userinput></screen>

	  <para>Enabling <varname>vfs.usermount</varname>, however, has
	    negative security implications.  A better way to access
	    &ms-dos; formatted media is to use the <filename
	      role="package">emulators/mtools</filename> package in the
	    Ports Collection.</para>

	  <note>
	    <para>The device name used in the previous examples must be
	      changed according to your configuration.</para>
	  </note>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="du-vs-df">
	  <para>The <command>du</command> and <command>df</command>
	    commands show different amounts of disk space available.
	    What is going on?</para>
	</question>

	<answer>
	  <para>You need to understand what <command>du</command> and
	    <command>df</command> really do.  <command>du</command> goes
	    through the directory tree, measures how large each file is,
	    and presents the totals.  <command>df</command> 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 <command>df</command> but not
	    <command>du</command>.</para>

	  <para>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
	    <command>more</command>.  Assume you have a file large
	    enough that its presence affects the output of
	    <command>du</command> and <command>df</command>.  (Since
	    disks can be so large today, this might be a
	    <emphasis>very</emphasis> large file!) If you delete this
	    file while using <command>more</command> on it,
	    <command>more</command> 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.  <command>du</command> shows that it is gone
	    &mdash; it has walked the directory tree and the file is not
	    listed.  <command>df</command> shows that it is still there,
	    as the file system knows that <command>more</command> is
	    still using that space.  Once you end the
	    <command>more</command> session, <command>du</command> and
	    <command>df</command> will agree.</para>

	  <para>This situation is common on web servers.  Many people
	    set up a &os; web server and forget to rotate the log files.
	    The access log fills up <filename class="directory">/var</filename>.  The new
	    administrator deletes the file, but the system still
	    complains that the partition is full.  Stopping and
	    restarting the web server program would free the file,
	    allowing the system to release the disk space.  To prevent
	    this from happening, set up &man.newsyslog.8;.</para>

	  <para>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!</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="add-swap-space">
	  <para>How can I add more swap space?</para>
	</question>

	<answer>
	  <para>In the <ulink
	      url="&url.books.handbook;/config-tuning.html">Configuration and Tuning</ulink>
	    section of the Handbook, you will find a <ulink
	      url="&url.books.handbook;/adding-swap-space.html">section</ulink>
	    describing how to do this.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="manufacturer-disk-size">
	  <para>Why does &os; see my disk as smaller than the
	    manufacturer says it is?</para>
	</question>

	<answer>
	  <para>Disk manufacturers calculate gigabytes as a billion
	    bytes each, whereas &os; calculates them as
	    1,073,741,824&nbsp;bytes each.  This explains why, for
	    example, &os;'s boot messages will report a disk that
	    supposedly has 80&nbsp;GB as holding 76,319&nbsp;MB.</para>

	  <para>Also note that &os; will (by default) <link
	      linkend="disk-more-than-full">reserve</link> 8% of the disk
	    space.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="disk-more-than-full">
	  <para>How is it possible for a partition to be more than 100%
	    full?</para>
	</question>

	<answer>
	  <para>A portion of each UFS partition (8%, by default) is
	    reserved for use by the operating system and the
	    <username>root</username> user.  &man.df.1; does not count
	    that space when calculating the <literal>Capacity</literal>
	    column, so it can exceed 100%.  Also, you will notice that
	    the <literal>Blocks</literal> column is always greater than
	    the sum of the <literal>Used</literal> and
	    <literal>Avail</literal> columns, usually by a factor of
	    8%.</para>

	  <para>For more details, look up <option>-m</option>
	    in &man.tunefs.8;.</para>
	</answer>
      </qandaentry>
    </qandaset>

    <sect1 id="all-about-zfs">
      <title>ZFS</title>

      <qandaset>
	<qandaentry>
	  <question id="how-much-ram-for-zfs">
	    <para>What is the minimum amount of RAM one should have to
	      run ZFS?</para>
	  </question>

	  <answer>
	    <para>A minimum of 4GB of RAM is required for comfortable
	      usage, but individual workloads can vary widely.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="what-is-zil">
	    <para>What is the ZIL and when does it get used?</para>
	  </question>

	  <answer>
	    <para>The <acronym>ZIL</acronym> ((<acronym>ZFS</acronym>
	      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 (<quote>Transaction Group
		Commit</quote>).  However syscalls like &man.fsync.2;
	      require a commitment that the data is written to stable
	      storage before returning.
	      The ZIL is needed for writes that have been acknowledged
	      as written but which are not yet on disk as part of a
	      transaction.  The transaction groups are timestamped.
	      In the event of a crash the last valid timestamp is
	      found and missing data is merged in from the ZIL.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="need-ssd-for-zil">
	    <para>Do I need a SSD for ZIL?</para>
	  </question>

	  <answer>
	    <para>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.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="what-is-l2arc">
	    <para>What is the L2ARC?</para>
	  </question>

	  <answer>
	    <para>The <acronym>L2ARC</acronym> is a read cache stored
	      on a fast device such as an <acronym>SSD</acronym>.
	      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.</para>

	    <para>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.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="should-enable-dedup">
	    <para>Is enabling deduplication advisable?</para>
	  </question>

	  <answer>
	    <para>Generally speaking, no.</para>

	    <para>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.</para>

	    <para>Deduplication can also lead to some unexpected
	      situations.  In particular deleting files may become much
	      slower.</para>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="zpool-fully-full">
	    <para>I can not delete or create files on my ZFS pool.
	      How can I fix this?</para>
	  </question>

	  <answer>
	    <para>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.</para>

	    <screen>&prompt.user; <userinput>truncate -s 0 <replaceable>unimportant-file</replaceable></userinput></screen>

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

	    <note>
	      <para>On systems with additional ZFS dataset tuning,
		such as deduplication, the space may not be immediately
		available</para>
	    </note>
	  </answer>
	</qandaentry>

	<qandaentry>
	  <question id="zfs-ssd-trim">
	    <para>Does ZFS support TRIM for Solid State Drives?</para>
	  </question>

	  <answer>
	    <para>ZFS TRIM support was added to &os;&nbsp;10-CURRENT
	      with revision r<svnref>240868</svnref>.  ZFS TRIM
	      support is not yet available on the -STABLE
	      branches.</para>

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

	    <programlisting>vfs.zfs.trim_disable=1</programlisting>

	    <note>
	      <para>ZFS TRIM may not work with all configurations,
		such as a ZFS filesystem on a GELI-backed
		device.</para>
	    </note>
	  </answer>
	</qandaentry>
      </qandaset>
    </sect1>
  </chapter>

  <chapter id="admin">
    <title>System Administration</title>

    <qandaset>
      <qandaentry>
	<question id="startup-config-files">
	  <para>Where are the system start-up configuration
	    files?</para>
	</question>

	<answer>
	  <para>The primary configuration file is
	    <filename>/etc/defaults/rc.conf</filename> (see
	    &man.rc.conf.5;).  System startup scripts such as
	    <filename class="directory">/etc/rc</filename> and
	    <filename class="directory">/etc/rc.d</filename> (see &man.rc.8;) just include
	    this file.  <emphasis>Do not edit this file!</emphasis>
	    Instead, if there is any entry in
	    <filename>/etc/defaults/rc.conf</filename> that you want to
	    change, you should copy the line into
	    <filename>/etc/rc.conf</filename> and change it
	    there.</para>

	  <para>For example, if you wish to start &man.named.8;, the
	    included DNS server, all you need to do is:</para>

	  <screen>&prompt.root; <userinput>echo 'named_enable="YES"' &gt;&gt; /etc/rc.conf</userinput></screen>

	  <para>To start up local services, place shell scripts in the
	    <filename class="directory">/usr/local/etc/rc.d</filename> directory.  These
	    shell scripts should be set executable, the default file
	    mode is <literal>555</literal>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="adding-users">
	  <para>How do I add a user easily?</para>
	</question>

	<answer>
	  <para>Use the &man.adduser.8; command, or the &man.pw.8;
	    command for more complicated situations.</para>

	  <para>To remove the user, use the &man.rmuser.8; command or,
	    if necessary, &man.pw.8;.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="root-not-found-cron-errors">
	  <para>Why do I keep getting messages like <errorname>root: not
	      found</errorname> after editing
	    <filename>/etc/crontab</filename></para>
	</question>

	<answer>
	  <para>This is normally caused by editing the system crontab
	    (<filename>/etc/crontab</filename>) and then using
	    &man.crontab.1; to install it:</para>

	  <screen>&prompt.root; <userinput>crontab /etc/crontab</userinput></screen>

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

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

	  <screen>&prompt.root; <userinput>crontab -r</userinput></screen>

	  <para>Next time, when you edit
	    <filename>/etc/crontab</filename>, you should not do
	    anything to inform &man.cron.8; of the changes, since it
	    will notice them automatically.</para>

	  <para>If you want something to be run once per day, week, or
	    month, it is probably better to add shell scripts
	    <filename class="directory">/usr/local/etc/periodic</filename>, and let the
	    &man.periodic.8; command run from the system
	    <command>cron</command> schedule it with the other periodic
	    system tasks.</para>

	  <para>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
	    &os;, this is <username>root</username> for all entries.
	    When this crontab is used as the <username>root</username>
	    user's crontab (which is <emphasis>not</emphasis> the same
	    as the system crontab), &man.cron.8; assumes the string
	    <literal>root</literal> is the first word of the command to
	    execute, but no such command exists.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="su-wheel-group">
	  <para>Why do I get the error, <errorname>you are not in the
	      correct group to su root</errorname> when I try to
	    <command>su</command> to <username>root</username>?</para>
	</question>

	<answer>
	  <para>This is a security feature.  To
	    <command>su</command> to <username>root</username> (or any
	    other account with superuser privileges), you must be in the
	    <groupname>wheel</groupname> group.  If this feature were
	    not there, anybody with an account on a system who also
	    found out <username>root</username>'s password would be able
	    to gain superuser level access to the system.  With this
	    feature, this is not strictly true; &man.su.1; will prevent
	    them from even trying to enter the password if they are not
	    in <groupname>wheel</groupname>.</para>

	  <para>To allow someone to <command>su</command> to
	    <username>root</username>, simply put them in the
	    <groupname>wheel</groupname> group.  Use &man.pw.8;
	    for this purpose.</para>

	  <screen>&prompt.root; <userinput>pw groupmod wheel -m <replaceable>lisa</replaceable></userinput></screen>

	  <para>The above example will add user
	    <username>lisa</username> to the group
	    <groupname>wheel</groupname>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="rcconf-readonly">
	  <para>I made a mistake in <filename>rc.conf</filename>, or
	    another startup file, and now I cannot edit it because the
	    file system is read-only.  What should I do?</para>
	</question>

	<answer>
	  <para>Restart the system using <userinput>boot -s</userinput>
	    at the loader prompt to enter Single User mode.  When
	    prompted for a shell pathname, simply press
	    <keycap>Enter</keycap>, and run
	    <command>mount -urw /</command> to re-mount the root file
	    system in read/write mode.  You may also need to run
	    <command>mount -a -t ufs</command> 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 &man.ed.1;.</para>

	  <para>If you intend to use a full screen editor such as
	    &man.vi.1; or &man.emacs.1;, you may also need to run
	    <command>export TERM=xterm</command> on &os; 9.0+, or
	    <command>export TERM=cons25</command> on &os; 8.X
	    so that these editors
	    can load the correct data from the &man.termcap.5;
	    database.</para>

	  <para>Once you have performed these steps, you can edit
	    <filename>/etc/rc.conf</filename> 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="printer-setup">
	  <para>Why am I having trouble setting up my printer?</para>
	</question>

	<answer>
	  <para>See the <ulink
	      url="&url.books.handbook;/printing.html">Handbook entry on printing</ulink>.
	    It should cover most of your problem.</para>

	  <para>Some printers require a host-based driver to do any kind
	    of printing.  These so-called <quote>WinPrinters</quote> are
	    not natively supported by &os;.  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
	    <filename role="package">print/pnm2ppa</filename> port
	    supports it.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="keyboard-mappings">
	  <para>How can I correct the keyboard mappings for my
	    system?</para>
	</question>

	<answer>
	  <para>Please see the Handbook section on <ulink
	      url="&url.books.handbook;/using-localization.html">using localization</ulink>,
	    specifically the section on <ulink
	      url="&url.books.handbook;/using-localization.html#setting-console">console setup</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="user-quotas">
	  <para>Why can I not get user quotas to work properly?</para>
	</question>

	<answer>
	  <orderedlist>
	    <listitem>
	      <para>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:</para>

	      <programlisting>options QUOTA</programlisting>

	      <para>Please read the <ulink
		  url="&url.books.handbook;/quotas.html">Handbook entry on quotas</ulink>
		for full details.</para>
	    </listitem>

	    <listitem>
	      <para>Do not turn on quotas on
		<filename class="directory">/</filename>.</para>
	    </listitem>

	    <listitem>
	      <para>Put the quota file on the file system that the
		quotas are to be enforced on, i.e.:</para>

	      <informaltable frame="none" pgwide="1">
		<tgroup cols="2">
		  <thead>
		    <row>
		      <entry>File System</entry>

		      <entry>Quota file</entry>
		    </row>
		  </thead>

		  <tbody>
		    <row>
		      <entry><filename class="directory">/usr</filename></entry>

		      <entry><filename>/usr/admin/quotas</filename></entry>
		    </row>

		    <row>
		      <entry><filename class="directory">/home</filename></entry>

		      <entry><filename>/home/admin/quotas</filename></entry>
		    </row>

		    <row>
		      <entry>&hellip;</entry>

		      <entry>&hellip;</entry>
		    </row>
		  </tbody>
		</tgroup>
	      </informaltable>
	    </listitem>
	  </orderedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="sysv-ipc">
	  <para>Does &os; support System V IPC primitives?</para>
	</question>

	<answer>
	  <para>Yes, &os; supports System V-style IPC, including shared
	    memory, messages and semaphores, in the
	    <filename>GENERIC</filename> kernel.  With a custom kernel,
	    support may be loaded with the <filename>sysvshm.ko</filename>,
	    <filename>sysvsem.ko</filename> and <filename>
	      sysvmsg.ko</filename> kernel modules, or
	    enabled in the custom kernel by adding the following lines to your
	    kernel config:</para>

	  <programlisting>options    SYSVSHM          # enable shared memory
options    SYSVSEM          # enable for semaphores
options    SYSVMSG          # enable for messaging</programlisting>

	  <para>Recompile and install your kernel.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="sendmail-alternative">
	  <para>What other mail-server software can I use instead of
	    <application>sendmail</application>?</para>
	</question>

	<answer>
	  <para>The <ulink
	      url="http://www.sendmail.org/"><application>sendmail</application></ulink>
	    server is the default mail-server software for &os;, but you
	    can easily replace it with one of the other MTA (for
	    instance, an MTA installed from the ports).</para>

	  <para>There are various alternative MTAs in the ports tree
	    already, with <filename role="package">mail/exim</filename>,
	    <filename role="package">mail/postfix</filename>, <filename
	      role="package">mail/qmail</filename>, and <filename
	      role="package">mail/zmailer</filename> being some of the
	    most popular choices.</para>

	  <para>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
	    <quote>Is <application>sendmail</application> better than
	      <application>qmail</application>?</quote> 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="forgot-root-pw">
	  <para>I have forgotten the <username>root</username> password!
	    What do I do?</para>
	</question>

	<answer>
	  <para>Do not panic!  Restart the system, type
	    <userinput>boot -s</userinput> at the
	    <literal>Boot:</literal> prompt to enter Single User mode.
	    At the question about the shell to use, hit
	    <keycap>Enter</keycap>.  You will be dropped to a
	    &prompt.root; prompt.  Enter <command>mount -urw /</command>
	    to remount your root file system read/write, then run
	    <command>mount -a</command> to remount all the file systems.
	    Run <command>passwd root</command> to change the
	    <username>root</username> password then run &man.exit.1; to
	    continue booting.</para>

	  <note>
	    <para>If you are still prompted to give the
	      <username>root</username> password when entering the
	      Single User mode, it means that the console has been
	      marked as <literal>insecure</literal> in
	      <filename>/etc/ttys</filename>.  In this case it will be
	      required to boot from a &os; installation disk, choose
	      the <guimenuitem>Live CD</guimenuitem> or
	      <guimenuitem>Shell</guimenuitem> 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 <command>mount -urw /</command> by
	      <command>mount /dev/ada0p1 /mnt; chroot /mnt</command> for
	      a system on <replaceable>ada0p1</replaceable>.</para>
	  </note>

	  <note>
	    <para>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 &os; <ulink
		url="&url.books.handbook;/disks-encrypting.html">Handbook</ulink>.</para>
	  </note>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="CAD-reboot">
	  <para>How do I keep <keycombo
	      action="simul"><keycap>Control</keycap><keycap>Alt</keycap><keycap>Delete</keycap></keycombo>
	    from rebooting the system?</para>
	</question>

	<answer>
	  <para>If you are using &man.syscons.4; (the default console
	    driver) build and install a new kernel with the line in the
	    configuration file:</para>

	  <programlisting>options SC_DISABLE_REBOOT</programlisting>

	  <para>This can also be done by setting the following
	    &man.sysctl.8; which does not require a reboot or kernel
	    recompile:</para>

	  <screen>&prompt.root; <userinput>sysctl hw.syscons.kbd_reboot=0</userinput></screen>

	  <note>
	    <para>The above two methods are exclusive:  The &man.sysctl.8;
	      does not exist if you compile your kernel with the
	      <literal>SC_DISABLE_REBOOT</literal> option.</para>
	  </note>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="dos-to-unix-txt">
	  <para>How do I reformat DOS text files to &unix; ones?</para>
	</question>

	<answer>
	  <para>Use this &man.perl.1; command:</para>

	  <screen>&prompt.user; <userinput>perl -i.bak -npe 's/\r\n/\n/g' <replaceable>file(s)</replaceable></userinput></screen>

	  <para>where <replaceable>file(s)</replaceable> is one or more
	    files to process.  The modification is done in-place, with the
	    original file stored with a <filename>.bak</filename>
	    extension.</para>

	  <para>Alternatively you can use the &man.tr.1; command:</para>

	  <screen>&prompt.user; <userinput>tr -d '\r' &lt; <replaceable>dos-text-file</replaceable> &gt; <replaceable>unix-file</replaceable></userinput></screen>

	  <para><replaceable>dos-text-file</replaceable> is the file
	    containing DOS text while
	    <replaceable>unix-file</replaceable> will contain the
	    converted output.  This can be quite a bit faster than using
	    <command>perl</command>.</para>

	  <para>Yet another way to reformat DOS text files is to use the
	    <filename role="package">converters/dosunix</filename> port
	    from the Ports Collection.  Consult its documentation about
	    the details.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="kill-by-name">
	  <para>How do I kill processes by name?</para>
	</question>

	<answer>
	  <para>Use &man.pkill.1;.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="reread-rc">
	  <para>How do I re-read <filename>/etc/rc.conf</filename> and
	    re-start <filename>/etc/rc</filename> without a
	    reboot?</para>
	</question>

	<answer>
	  <para>Go into single user mode and then back to multi user
	    mode.</para>

	  <para>On the console do:</para>

	  <screen>&prompt.root; <userinput>shutdown now</userinput>
(Note: without -r or -h)

&prompt.root; <userinput>return</userinput>
&prompt.root; <userinput>exit</userinput></screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="release-candidate">
	  <para>I tried to update my system to the latest
	    <emphasis>-STABLE</emphasis>, but got
	    <emphasis>-BETA<replaceable>x</replaceable></emphasis>,
	    <emphasis>-RC</emphasis> or
	    <emphasis>-PRERELEASE</emphasis>!  What is going on?</para>
	</question>

	<answer>
	  <para>Short answer: it is just a name.
	    <emphasis>RC</emphasis> stands for <quote>Release
	      Candidate</quote>.  It signifies that a release is imminent.
	    In &os;, <emphasis>-PRERELEASE</emphasis> is typically
	    synonymous with the code freeze before a release.  (For some
	    releases, the <emphasis>-BETA</emphasis> label was used in
	    the same way as <emphasis>-PRERELEASE</emphasis>.)</para>

	  <para>Long answer: &os; derives its releases from one of two
	    places.  Major, dot-zero, releases, such as 9.0-RELEASE
	    are branched from the head of the development
	    stream, commonly referred to as <link
	      linkend="current">-CURRENT</link>.  Minor releases, such as
	    6.3-RELEASE or 5.2-RELEASE, have been snapshots of the
	    active <link linkend="stable">-STABLE</link> 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).</para>

	  <para>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.</para>

	  <para>For more information on version numbers and the various
	    Subversion branches, refer to the <ulink
	      url="&url.articles.releng;/article.html">Release Engineering</ulink>
	    article.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="kernel-chflag-failure">
	  <para>I tried to install a new kernel, and the &man.chflags.1;
	    failed.  How do I get around this?</para>
	</question>

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

	  <para>Long answer: &os; disallows changing system flags at
	    security levels greater than 0.  You can check your security
	    level with the command:</para>

	  <screen>&prompt.root; <userinput>sysctl kern.securelevel</userinput></screen>

	  <para>You cannot lower the security level; you have to boot to
	    Single Mode to install the kernel, or change the security
	    level in <filename>/etc/rc.conf</filename> then reboot.  See
	    the &man.init.8; manual page for details on
	    <literal>securelevel</literal>, and see
	    <filename>/etc/defaults/rc.conf</filename> and the
	    &man.rc.conf.5; manual page for more information on
	    <filename>rc.conf</filename>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="kernel-securelevel-time">
	  <para>I cannot change the time on my system by more than one
	    second!  How do I get around this?</para>
	</question>

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

	  <para>Long answer: &os; disallows changing the time by more
	    that one second at security levels greater than 1.  You can
	    check your security level with the command:</para>

	  <screen>&prompt.root; <userinput>sysctl kern.securelevel</userinput></screen>

	  <para>You cannot lower the security level; you have to boot to
	    Single User mode to change the date, or change the security
	    level in <filename>/etc/rc.conf</filename> then reboot.  See
	    the &man.init.8; manual page for details on
	    <literal>securelevel</literal>, and see
	    <filename>/etc/defaults/rc.conf</filename> and the
	    &man.rc.conf.5; manual page for more information on
	    <filename>rc.conf</filename>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="statd-mem-leak">
	  <para>Why is <command>rpc.statd</command> using 256&nbsp;MB of
	    memory?</para>
	</question>

	<answer>
	  <para>No, there is no memory leak, and it is not using
	    256&nbsp;MB of memory.  For convenience,
	    <command>rpc.statd</command> maps an obscene amount of
	    memory into its address space.  There is nothing terribly
	    wrong with this from a technical standpoint; it just throws
	    off things like &man.top.1; and &man.ps.1;.</para>

	  <para>&man.rpc.statd.8; maps its status file (resident on
	    <filename class="directory">/var</filename>) into its address space; to save
	    worrying about remapping it later when it needs to grow, it
	    maps it with a generous size.  This is very evident from the
	    source code, where one can see that the length argument to
	    &man.mmap.2; is <literal>0x10000000</literal>, or one
	    sixteenth of the address space on an IA32, or exactly
	    256&nbsp;MB.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="unsetting-schg">
	  <para>Why can I not unset the <literal>schg</literal> file
	    flag?</para>
	</question>

	<answer>
	  <para>You are running at an elevated (i.e., greater than 0)
	    securelevel.  Lower the securelevel and try again.  For more
	    information, see <link linkend="securelevel">the FAQ entry
	      on securelevel</link> and the &man.init.8; manual
	    page.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ssh-shosts">
	  <para>Why does <application>SSH</application> authentication
	    through <filename>.shosts</filename> not work by default in
	    recent versions of &os;?</para>
	</question>

	<answer>
	  <para>The reason why <filename>.shosts</filename>
	    authentication does not work by default in more recent
	    versions of &os; is because &man.ssh.1; is not installed
	    suid <username>root</username> by default.  To
	    <quote>fix</quote> this, you can do one of the
	    following:</para>

	  <itemizedlist>
	    <listitem>
	      <para>As a permanent fix, set
		<makevar>ENABLE_SUID_SSH</makevar> to
		<literal>true</literal> in
		<filename>/etc/make.conf</filename> then rebuild and
		reinstall &man.ssh.1;.</para>
	    </listitem>

	    <listitem>
	      <para>As a temporary fix, change the mode on
		<filename>/usr/bin/ssh</filename> to
		<literal>4555</literal> by running
		<command>chmod 4555 /usr/bin/ssh</command> as
		<username>root</username>.</para>
	    </listitem>
	  </itemizedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="vnlru">
	  <para>What is <literal>vnlru</literal>?</para>
	</question>

	<answer>
	  <para><literal>vnlru</literal> flushes and frees vnodes when
	    the system hits the <varname>kern.maxvnodes</varname> 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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="top-memory-states">
	  <para>What do the various memory states displayed by
	    <command>top</command> mean?</para>
	</question>

	<!-- Provided by John Dyson via Usenet -->
	<answer>
	  <itemizedlist>
	    <listitem>
	      <para><literal>Active</literal>: pages recently
		statistically used.</para>
	    </listitem>

	    <listitem>
	      <para><literal>Inactive</literal>: pages recently
		statistically unused.</para>
	    </listitem>

	    <listitem>
	      <para><literal>Cache</literal>: (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 <literal>active</literal> to
		<literal>cache</literal> 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.</para>
	    </listitem>

	    <listitem>
	      <para><literal>Free</literal>: 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.</para>
	    </listitem>

	    <listitem>
	      <para><literal>Wired</literal>: pages that are fixed into
		memory, usually for kernel purposes, but also sometimes
		for special use in processes.</para>
	    </listitem>
	  </itemizedlist>

	  <para>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.</para>

	  <para>There are some other flags (e.g., busy flag or busy
	    count) that might modify some of the described rules.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="free-memory-amount">
	  <para>How much free memory is available?</para>
	</question>

	<!-- Provided by John Dyson via Usenet -->
	<answer>
	  <para>There are a couple of kinds of <quote>free
	      memory</quote>.  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 <quote>free memory</quote> is the
	    total amount of <acronym>VM</acronym> space.  That can be
	    complex, but is dependent upon the amount of swap space and
	    memory.  Other kinds of <quote>free memory</quote>
	    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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="var-empty">
	  <para>What is <filename class="directory">/var/empty</filename>?  I can not
	    delete it!</para>
	</question>

	<answer>
	  <para><filename class="directory">/var/empty</filename> is a directory that the
	    &man.sshd.8; program uses when performing privilege separation.
	    The <filename class="directory">/var/empty</filename> directory is empty, owned by
	    <username>root</username> and has the <literal>schg</literal>
	    flag set.</para>

	  <para>Although it is not recommended to delete this directory, to
	    do so you will need to unset the <literal>schg</literal> flag
	    first.  See the &man.chflags.1; manual page for more information
	    (and bear in mind the answer to
	    <link linkend="unsetting-schg">the question on unsetting the schg flag</link>).</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="newsyslog-expectations">
	  <para>I just changed
	    <filename>/etc/newsyslog.conf</filename>. How can I check
	    if it does what I expect?</para>
	</question>

	<answer>
	  <para>To see what &man.newsyslog.8; will do use the
	    following:</para>

	  <screen>&prompt.user; <userinput>newsyslog -nrvv</userinput></screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="timezone">
	  <para>My time is wrong, how can I change the
	    timezone?</para>
	</question>

	<answer>
	  <para>Use &man.tzsetup.8;.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="x">
    <title>The X Window System and Virtual Consoles</title>

    <qandaset>
      <qandaentry>
	<question id="whatis-X">
	  <para>What is the X Window System?</para>
	</question>

	<answer>
	  <para>The X Window System (commonly <literal>X11</literal>) is
	    the most widely available windowing system capable of running
	    on &unix; or &unix;&nbsp;like systems, including &os;.
	    <ulink url= "http://www.x.org/wiki/">The X.Org Foundation</ulink>
	    administers the <ulink
	      url="http://en.wikipedia.org/wiki/X_Window_System_core_protocol">X protocol standards</ulink>,
	    with the current reference implementation, version 11
	    release &xorg.version;, so you will often see references
	    shortened to <literal>X11</literal>.</para>

	  <para>Many implementations are available for different
	    architectures and operating systems.  An implementation of
	    the server-side code is properly known as an <literal>X
	      server</literal>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="running-X">
	  <para>I want to run &xorg;, how do I go about it?</para>
	</question>

	<answer>
	  <para>To install &xorg; do one of the following:</para>

	  <para>Use the <filename role="package">x11/xorg</filename>
	    meta-port, which builds and installs every &xorg;
	    component.</para>

	  <para>Use <filename
	      role="package">x11/xorg-minimal</filename>, which builds
	    and installs only the necessary &xorg; components.</para>

	  <para>Install &xorg; from &os; packages:</para>

	  <screen><userinput>&prompt.root; pkg_add -r xorg</userinput></screen>

	  <para>or on systems using <application>pkg</application>:</para>

	  <screen><userinput>&prompt.root; pkg install xorg</userinput></screen>

	  <para>After the installation of &xorg;, follow
	    the instructions from the <ulink
	      url="&url.books.handbook;/x-config.html">X11 Configuration</ulink> section of
	    the &os; Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="running-X-securelevels">
	  <para>I <emphasis>tried</emphasis> to run X, but I get a
	    <errorname>No devices detected.</errorname> error when I
	    type
	    <command>startx</command>.  What do I do now?</para>
	</question>

	<answer>
	  <para>Your system is probably running at a raised
	    <literal>securelevel</literal>.  It is not possible to start X
	    at a raised <literal>securelevel</literal> because X
	    requires write access to &man.io.4;.  For more information,
	    see at the &man.init.8; manual page.</para>

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

	  <para>See <xref linkend="xdm-boot"/> for more information about
	    running &man.xdm.1; at boot time.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="x-and-moused">
	  <para>Why does my mouse not work with X?</para>
	</question>

	<answer>
	  <para>If you are using &man.syscons.4; (the default console
	    driver), you can configure &os; to support a mouse pointer on
	    each virtual screen.  To avoid conflicting with X,
	    &man.syscons.4; supports a virtual device called
	    <devicename>/dev/sysmouse</devicename>.  All mouse events
	    received from the real mouse device are written to the
	    &man.sysmouse.4; device via &man.moused.8;.  To use your
	    mouse on one or more virtual consoles,
	    <emphasis>and</emphasis> use X, see <xref
	      linkend="moused" remap="another section"/> and set up
	    &man.moused.8;.</para>

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

	  <programlisting>Section "InputDevice"
   Option          "Protocol" "SysMouse"
   Option          "Device" "/dev/sysmouse"
.....</programlisting>

	  <para>Starting with &xorg; version 7.4, the
	    <literal>InputDevice</literal> sections in
	    <filename>xorg.conf</filename> are ignored in favor of
	    autodetected devices.  To restore the old behavior, add the
	    following line to the <literal>ServerLayout</literal> or
	    <literal>ServerFlags</literal> section:</para>

	  <programlisting>Option "AutoAddDevices" "false"</programlisting>

	  <para>Some people prefer to use
	    <devicename>/dev/mouse</devicename> under X.  To make this
	    work, <devicename>/dev/mouse</devicename> should be linked
	    to <devicename>/dev/sysmouse</devicename> (see
	    &man.sysmouse.4;) by adding the following line to
	    <filename>/etc/devfs.conf</filename> (see
	    &man.devfs.conf.5;):</para>

	  <programlisting>link    sysmouse    mouse</programlisting>

	  <para>This link can be created by restarting &man.devfs.5;
	    with the following command (as
	    <username>root</username>):</para>

	  <screen>&prompt.root; <userinput>service devfs restart</userinput></screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="x-and-wheel">
	  <para>My mouse has a fancy wheel.  Can I use it in X?</para>
	</question>

	<answer>
	  <para>Yes.</para>

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

	  <example>
	    <title><quote>InputDevice</quote> Section for Wheeled Mouse
	      in &xorg; Configuration File</title>

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

	  <example>
	    <title><quote>.emacs</quote> Example for Naive Page
	      Scrolling with Wheeled Mouse (optional)</title>

	    <programlisting>;; wheel mouse
(global-set-key [mouse-4] 'scroll-down)
(global-set-key [mouse-5] 'scroll-up)</programlisting>
	  </example>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="x-and-synaptic">
	  <para>My laptop has a Synaptics touchpad.  Can I use
	    it in X?</para>
	</question>

	<answer>
	  <para>Yes, you will have to configure a few things to
	    make it work.</para>

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

	  <para>To enable synaptics in the &man.psm.4; driver you need
	    to add the following into
	    <filename>/boot/loader.conf</filename>:</para>

	  <programlisting>hw.psm.synaptics_support="1"</programlisting>

	  <para>You also need the following into
	    <filename>xorg.conf</filename>:</para>

	  <programlisting>Section "InputDevice"
Identifier  "Touchpad0"
Driver      "synaptics"
Option      "Protocol" "psm"
Option      "Device" "/dev/psm0"
EndSection</programlisting>

	  <para>And be sure to add the following into the
	    <quote>ServerLayout</quote> section:</para>

	  <programlisting>InputDevice    "Touchpad0" "SendCoreEvents"</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="no-remote-x11">
	  <para>How do I use remote X displays?</para>
	</question>

	<answer>
	  <para>For security reasons, the default setting is to not
	    allow a machine to remotely open a window.</para>

	  <para>To enable this feature, simply start
	    <application>X</application> with the optional
	    <option>-listen_tcp</option> argument:</para>

	  <screen>&prompt.user; <userinput>startx -listen_tcp</userinput></screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="virtual-console">
	  <para>What is a virtual console and how do I make more?</para>
	</question>

	<answer>
	  <para>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.</para>

	  <para>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.</para>

	  <para>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 <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F2</keycap></keycombo>
	    (hold down <keycap>Alt</keycap> and press
	    <keycap>F2</keycap>), and you will find a login prompt
	    waiting for you on the second <quote>virtual
	      console</quote>!  When you want to go back to the original
	    session, do <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F1</keycap></keycombo>.</para>

	  <para>The default &os; installation has eight virtual consoles
	    enabled.  <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F1</keycap></keycombo>,
	    <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F2</keycap></keycombo>,
	    <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F3</keycap></keycombo>,
	    and so on will switch between these virtual consoles.</para>

	  <para>To enable more of them, edit
	    <filename>/etc/ttys</filename> (see &man.ttys.5;) and add
	    entries for <devicename>ttyv8</devicename> to
	    <devicename>ttyvc</devicename> after the comment on
	    <quote>Virtual terminals</quote>:</para>

	  <programlisting># Edit the existing entry for ttyv8 in /etc/ttys and change
# "off" to "on".
ttyv8   "/usr/libexec/getty Pc"         xterm  on secure
ttyv9   "/usr/libexec/getty Pc"         xterm  on secure
ttyva   "/usr/libexec/getty Pc"         xterm  on secure
ttyvb   "/usr/libexec/getty Pc"         xterm  on secure</programlisting>

	  <para>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&nbsp;MB RAM or less.  You may
	    also want to change the <literal>secure</literal> to
	    <literal>insecure</literal>.</para>

	  <note>
	    <para>Versions of &os; prior to 9.0 used the <quote>
		cons25</quote> terminal type, and not <quote>
		xterm</quote>.  Existing entries in
	      <filename>/etc/ttys</filename> can be used on which to
	      base new additions.</para>
	  </note>

	  <important>
	    <para>If you want to run an X server you
	      <emphasis>must</emphasis> 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
	      &mdash; you can only do this for eleven of them if you
	      also want to run an X server on the same machine.</para>
	  </important>

	  <para>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:</para>

	  <programlisting>ttyvb   "/usr/libexec/getty Pc"         xterm  on  secure</programlisting>

	  <para>to:</para>

	  <programlisting>ttyvb   "/usr/libexec/getty Pc"         xterm  off secure</programlisting>

	  <para>If your keyboard has only ten function keys, you would
	    end up with:</para>

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

	  <para>(You could also just delete these lines.)</para>

	  <para>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 <username>root</username>):</para>

	  <screen>&prompt.root; <userinput>kill -HUP 1</userinput></screen>

	  <para>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 <command>kill</command>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="vty-from-x">
	  <para>How do I access the virtual consoles from X?</para>
	</question>

	<answer>
	  <para>Use <keycombo
	      action="simul"><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>F<replaceable>n</replaceable></keycap></keycombo>
	    to switch back to a virtual console.  <keycombo
	      action="simul"><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>F1</keycap></keycombo>
	    would return you to the first virtual console.</para>

	  <para>Once you are back to a text console, you can then use
	    <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F<replaceable>n</replaceable></keycap></keycombo>
	    as normal to move between them.</para>

	  <para>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 <command>startx</command>) 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 <keycombo
	      action="simul"><keycap>Alt</keycap><keycap>F9</keycap></keycombo>
	    to return.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="xdm-boot">
	  <para>How do I start <application>XDM</application> on
	    boot?</para>
	</question>

	<answer>
	  <para>There are two schools of thought on how to start
	    &man.xdm.1;.  One school starts <command>xdm</command> from
	    <filename>/etc/ttys</filename> (see &man.ttys.5;) using the
	    supplied example, while the other simply runs
	    <command>xdm</command> from
	    <filename>rc.local</filename> (see &man.rc.8;) or from an
	    <filename>X</filename> script in
	    <filename class="directory">/usr/local/etc/rc.d</filename>.  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.</para>

	  <para>The &man.ttys.5; method has the advantage of documenting
	    which vty X will start on and passing the responsibility of
	    restarting the X server on logout to &man.init.8;.  The
	    &man.rc.8; method makes it easy to <command>kill</command>
	    <command>xdm</command> if there is a problem starting the X
	    server.</para>

	  <para>If loaded from &man.rc.8;, <command>xdm</command> should
	    be started without any arguments (i.e., as a daemon).
	    <command>xdm</command> must start
	    <emphasis>after</emphasis> &man.getty.8; runs, or else
	    <command>getty</command> and <command>xdm</command> will
	    conflict, locking out the console.  The best way around this
	    is to have the script sleep 10 seconds or so then launch
	    <command>xdm</command>.</para>

	  <para>If you are to start <command>xdm</command> from
	    <filename>/etc/ttys</filename>, there still is a chance of
	    conflict between <command>xdm</command> and &man.getty.8;.
	    One way to avoid this is to add the <literal>vt</literal>
	    number in
	    <filename>/usr/local/lib/X11/xdm/Xservers</filename></para>

	  <programlisting>:0 local /usr/local/bin/X vt4</programlisting>

	  <para>The above example will direct the X server to run in
	    <devicename>/dev/ttyv3</devicename>.  Note the number is
	    offset by one.  The X server counts the vty from one,
	    whereas the &os; kernel numbers the vty from zero.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="xconsole-failure">
	  <para>Why do I get <errorname>Couldn't open
	      console</errorname> when I run
	    <command>xconsole</command>?</para>
	</question>

	<answer>
	  <para>If you start <application>X</application> with
	    <command>startx</command>, the permissions on
	    <devicename>/dev/console</devicename> will
	    <emphasis>not</emphasis> get changed, resulting in things
	    like <command>xterm -C</command> and
	    <command>xconsole</command> not working.</para>

	  <para>This is because of the way console permissions are set
	    by default.  On a multi-user system, one does not
	    necessarily want just any user to be able to write on the
	    system console.  For users who are logging directly onto a
	    machine with a VTY, the &man.fbtab.5; file exists to solve
	    such problems.</para>

	  <para>In a nutshell, make sure an uncommented line of the form
	    is in <filename>/etc/fbtab</filename> (see
	    &man.fbtab.5;):</para>

	  <programlisting>/dev/ttyv0 0600 /dev/console</programlisting>

	  <para>It will ensure that whomever logs in on
	    <devicename>/dev/ttyv0</devicename> will own the
	    console.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ps2-x">
	  <para>Why does my PS/2 mouse misbehave under X?</para>
	</question>

	<answer>
	  <para>Your mouse and the mouse driver may have somewhat become
	    out of synchronization.</para>

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

	  <programlisting>psmintr: out of sync (xxxx != yyyy)</programlisting>

	  <para>and notice that your mouse does not work
	    properly.</para>

	  <para>If this happens, disable the synchronization check code
	    by setting the driver flags for the PS/2 mouse driver to
	    <literal>0x100</literal>.  This can be easiest achieved
	    by adding

	    <screen>hint.psm.0.flags="0x100"</screen>

	    to
	    <filename>/boot/loader.conf</filename> and rebooting.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mouse-button-reverse">
	  <para>How do I reverse the mouse buttons?</para>
	</question>

	<answer>
	  <para>Run the command <command>xmodmap -e "pointer = 3 2 1"</command>
	    from <filename>.xinitrc</filename> or
	    <filename>.xsession</filename>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="install-splash">
	  <para>How do I install a splash screen and where do I find
	    them?</para>
	</question>

	<answer>
	  <para>The detailed answer for this question can be found in
	    the <ulink
	      url="&url.books.handbook;/boot-blocks.html#boot-splash">Boot Time Splash Screens</ulink>
	    section of the &os; Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="windows-keys">
	  <para>Can I use the <keycap>Windows</keycap> keys on my
	    keyboard in X?</para>
	</question>

	<answer>
	  <para>Yes.  All you need to do is use &man.xmodmap.1; to
	    define what function you wish them to perform.</para>

	  <para>Assuming all <quote>Windows</quote> keyboards are
	    standard then the keycodes for these three keys are the
	    following:</para>

	  <itemizedlist>
	    <listitem>
	      <para><keycode>115</keycode> &mdash;
		<keycap>Windows</keycap> key, between the left-hand
		<keycap>Ctrl</keycap> and <keycap>Alt</keycap>
		keys</para>
	    </listitem>

	    <listitem>
	      <para><keycode>116</keycode> &mdash;
		<keycap>Windows</keycap> key, to the right of
		<keycap>AltGr</keycap></para>
	    </listitem>

	    <listitem>
	      <para><keycode>117</keycode> &mdash; <keycap>Menu</keycap>,
		to the left of the right-hand <keycap>Ctrl</keycap></para>
	    </listitem>
	  </itemizedlist>

	  <para>To have the left <keycap>Windows</keycap> key print a
	    comma, try this.</para>

	  <screen>&prompt.root; <userinput>xmodmap -e "keycode 115 = comma"</userinput></screen>

	  <para>To have the <keycap>Windows</keycap> key-mappings
	    enabled automatically every time you start X either put the
	    <command>xmodmap</command> commands in
	    <filename>~/.xinitrc</filename> or, preferably, create
	    a <filename>~/.xmodmaprc</filename> and include the
	    <command>xmodmap</command> options, one per line, then add
	    the following line to
	    <filename>~/.xinitrc</filename>:</para>

	  <programlisting>xmodmap $HOME/.xmodmaprc</programlisting>

	  <para>For example, you could map the 3 keys to be
	    <keycap>F13</keycap>, <keycap>F14</keycap>, and
	    <keycap>F15</keycap>, respectively.  This would make it easy
	    to map them to useful functions within applications or your
	    window manager, as demonstrated further down.</para>

	  <para>To do this put the following in
	    <filename>~/.xmodmaprc</filename>.</para>

	  <programlisting>keycode 115 = F13
keycode 116 = F14
keycode 117 = F15</programlisting>

	  <para>If you use the <filename
	      role="package">x11-wm/fvwm2</filename> port, for example,
	    you could map the keys so that <keycap>F13</keycap>
	    iconifies (or de-iconifies) the window the cursor is in,
	    <keycap>F14</keycap> brings the window the cursor is in to
	    the front or, if it is already at the front, pushes it to
	    the back, and <keycap>F15</keycap> 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).</para>

	  <para>The following entries in <filename>~/.fvwmrc</filename>
	    implement the aforementioned setup:</para>

	  <programlisting>Key F13        FTIWS    A        Iconify
Key F14        FTIWS    A        RaiseLower
Key F15        A        A        Menu Workplace Nop</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="x-3d-acceleration">
	  <para>How can I get 3D hardware acceleration for
	    &opengl;?</para>
	</question>

	<answer>
	  <para>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 &os; by installing one of the
	    following ports:</para>

	  <itemizedlist>
	    <listitem>
	      <para>The latest versions of nVidia cards are supported by
		the <filename role="package">x11/nvidia-driver</filename>
		port.</para>
	    </listitem>

	    <listitem>
	      <para>nVidia cards like the GeForce2&nbsp;MX/3/4 series
		are supported by the 96XX series of drivers, available
		in the <filename
		  role="package">x11/nvidia-driver-96xx</filename>
		port.</para>
	    </listitem>

	    <listitem>
	      <para>Even older cards, like GeForce and RIVA&nbsp;TNT are
		supported by the 71XX series of drivers, available in
		the <filename
		  role="package">x11/nvidia-driver-71xx</filename>
		port.</para>
	    </listitem>
	  </itemizedlist>

	  <para>nVidia provides detailed information on which
	    card is supported by which driver
	    on their web site: <ulink
	      url="http://www.nvidia.com/object/IO_32667.html"></ulink>.</para>

	  <para>For Matrox&nbsp;G200/G400, check the
	    <filename role="package">x11-servers/mga_hal</filename>
	    port.</para>

	  <para>For ATI&nbsp;Rage&nbsp;128 and Radeon see
	    &man.ati.4x;, &man.r128.4x; and &man.radeon.4x;.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="networking">
    <title>Networking</title>

    <qandaset>
      <qandaentry>
	<question id="diskless-booting">
	  <para>Where can I get information on <quote>diskless
	      booting</quote>?</para>
	</question>

	<answer>
	  <para><quote>Diskless booting</quote> means that the &os;
	    box is booted over a network, and reads the necessary
	    files from a server instead of its hard disk.  For full
	    details, please read <ulink
	      url="&url.books.handbook;/network-diskless.html">the Handbook entry on diskless booting</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="router">
	  <para>Can a &os; box be used as a dedicated network
	    router?</para>
	</question>

	<answer>
	  <para>Yes.  Please see the Handbook entry on <ulink
	      url="&url.books.handbook;/advanced-networking.html">advanced networking</ulink>,
	    specifically the section on <ulink
	      url="&url.books.handbook;/network-routing.html">routing and gateways</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="win95-connection">
	  <para>Can I connect my &windows; box to the Internet via
	    &os;?</para>
	</question>

	<answer>
	  <para>Typically, people who ask this question have two PCs at
	    home, one with &os; and one with some version of &windows;
	    the idea is to use the &os; box to connect to the Internet
	    and then be able to access the Internet from the &windows;
	    box through the &os; box.  This is really just a special
	    case of the previous question and works perfectly
	    well.</para>

	  <para>Dialup users must use <option>-nat</option>
	    and set
	    <literal>gateway_enable</literal> to
	    <emphasis>YES</emphasis> in
	    <filename>/etc/rc.conf</filename>.
	    For
	    more information, please see the &man.ppp.8; manual page or
	    the <ulink
	      url="&url.books.handbook;/userppp.html">Handbook entry on user PPP</ulink>.</para>

	  <para>If you are using kernel-mode PPP or have an Ethernet
	    connection to the Internet, you need to use &man.natd.8;.
	    Please look at the <ulink
	      url="&url.books.handbook;/network-natd.html">natd</ulink>
	    section of the Handbook for a tutorial.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="slip-ppp-support">
	  <para>Does &os; support PPP?</para>
	</question>

	<answer>
	  <para>Yes.  &man.ppp.8; provides support for both
	    incoming and outgoing connections.</para>

	  <para>For more information on how to use this, please see the
	    <ulink
	      url="&url.books.handbook;/ppp-and-slip.html">Handbook chapter on PPP</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="natd">
	  <para>Does &os; support NAT or Masquerading?</para>
	</question>

	<answer>
	  <para>Yes.  If you want to use NAT over a user PPP connection,
	    please see the <ulink
	      url="&url.books.handbook;/userppp.html">Handbook entry on user PPP</ulink>.
	    If you want to use NAT over some other sort of network
	    connection, please look at the <ulink
	      url="&url.books.handbook;/network-natd.html">natd</ulink>
	    section of the Handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ethernet-aliases">
	  <para>How can I set up Ethernet aliases?</para>
	</question>

	<answer>
	  <para>If the alias is on the same subnet as an address already
	    configured on the interface, then add <literal>netmask
	      0xffffffff</literal> to your &man.ifconfig.8; command-line,
	    as in the following:</para>

	  <screen>&prompt.root; <userinput>ifconfig <replaceable>ed0</replaceable> alias <replaceable>192.0.2.2</replaceable> netmask 0xffffffff</userinput></screen>

	  <para>Otherwise, just specify the network address and netmask
	    as usual:</para>

	  <screen>&prompt.root; <userinput>ifconfig <replaceable>ed0</replaceable> alias <replaceable>172.16.141.5</replaceable> netmask 0xffffff00</userinput></screen>

	  <para>You can read more about this in the &os; <ulink
	      url="&url.books.handbook;/configtuning-virtual-hosts.html">Handbook</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="nfs-linux">
	  <para>Why can I not NFS-mount from a &linux; box?</para>
	</question>

	<answer>
	  <para>Some versions of the &linux; NFS code only accept mount
	    requests from a privileged port; try to issue the following
	    command:</para>

	  <screen>&prompt.root; <userinput>mount -o -P <replaceable>linuxbox:/blah</replaceable> <replaceable>/mnt</replaceable></userinput></screen>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="exports-errors">
	  <para>Why does <command>mountd</command> keep telling me it
	    <errorname>can't change attributes</errorname> and that I
	    have a <errorname>bad exports list</errorname> on my &os;
	    NFS server?</para>
	</question>

	<answer>
	  <para>The most frequent problem is not understanding the
	    correct format of <filename>/etc/exports</filename>.  Please
	    review &man.exports.5; and the <ulink
	      url="&url.books.handbook;/network-nfs.html">NFS</ulink>
	    entry in the Handbook, especially the section on <ulink
	      url="&url.books.handbook;/network-nfs.html#configuring-nfs">configuring NFS</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ip-multicast">
	  <para>How do I enable IP multicast support?</para>
	</question>

	<answer>
	  <para>&os; 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 <literal>MROUTING</literal>
	    option and run &man.mrouted.8;.  &os; will start
	    &man.mrouted.8; at boot time if the flag
	    <literal>mrouted_enable</literal> is set to
	    <literal>YES</literal> in
	    <filename>/etc/rc.conf</filename>.</para>

	  <note>
	    <para>In recent &os; releases, the &man.mrouted.8; multicast
	      routing daemon, the &man.map-mbone.8; and &man.mrinfo.8;
	      utilities have been removed from the base system.  These
	      programs are now available in the &os; Ports Collection as
	      <filename role="package">net/mrouted</filename>.</para>
	  </note>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="fqdn-hosts">
	  <para>Why do I have to use the FQDN for hosts on my
	    site?</para>
	</question>

	<answer>
	  <para>See the answer in the &os; <ulink
	      url="&url.books.handbook;/mail-trouble.html">Handbook</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="network-permission-denied">
	  <para>Why do I get an error, <errorname>Permission
	      denied</errorname>, for all networking operations?</para>
	</question>

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

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

	  <screen>&prompt.root; <userinput>ipfw add 65534 allow all from any to any</userinput></screen>

	  <para>You can also set <literal>firewall_type="open"</literal>
	    in <filename>/etc/rc.conf</filename>.</para>

	  <para>For further information on configuring a &os; firewall,
	    see the <ulink
	      url="&url.books.handbook;/firewalls.html">Handbook chapter</ulink>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ipfw-fwd">
	  <para>Why is my <command>ipfw</command> <quote>fwd</quote>
	    rule to redirect a service to another machine not
	    working?</para>
	</question>

	<answer>
	  <para>Possibly because you want to do network address
	    translation (NAT) and not just forward packets.  A
	    <quote>fwd</quote> 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:</para>

	  <screen>01000 fwd <replaceable>10.0.0.1</replaceable> from any to <replaceable>foo 21</replaceable></screen>

	  <para>When a packet with a destination address of
	    <replaceable>foo</replaceable> arrives at the machine with
	    this rule, the packet is forwarded to
	    <replaceable>10.0.0.1</replaceable>, but it still has the
	    destination address of <replaceable>foo</replaceable>!  The
	    destination address of the packet is
	    <emphasis>not</emphasis> changed to
	    <replaceable>10.0.0.1</replaceable>.  Most machines would
	    probably drop a packet that they receive with a destination
	    address that is not their own.  Therefore, using a
	    <quote>fwd</quote> rule does not often work the way the user
	    expects.  This behavior is a feature and not a bug.</para>

	  <para>See the <link
	      linkend="service-redirect">FAQ about redirecting services</link>,
	    the &man.natd.8; manual, or one of the several port
	    redirecting utilities in the <ulink
	      url="&url.base;/ports/index.html">Ports Collection</ulink>
	    for a correct way to do this.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="service-redirect">
	  <para>How can I redirect service requests from one machine to
	    another?</para>
	</question>

	<answer>
	  <para>You can redirect FTP (and other service) request with
	    the <filename role="package">sysutils/socket</filename>
	    port.  Simply replace the service's command line to call
	    <command>socket</command> instead, like so:</para>

	  <programlisting>ftp stream tcp nowait nobody /usr/local/bin/socket socket <replaceable>ftp.example.com</replaceable> <replaceable>ftp</replaceable></programlisting>

	  <para>where <replaceable>ftp.example.com</replaceable> and
	    <replaceable>ftp</replaceable> are the host and port to
	    redirect to, respectively.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="bandwidth-mgr-tool">
	  <para>Where can I get a bandwidth management tool?</para>
	</question>

	<answer>
	  <para>There are three bandwidth management tools available for
	    &os;.  &man.dummynet.4; is integrated into &os; as part of
	    &man.ipfw.4;.  <ulink
	      url="http://www.sonycsl.co.jp/person/kjc/programs.html">ALTQ</ulink>
	    has been integrated into &os; as part of &man.pf.4;.
	    Bandwidth Manager from <ulink
	      url="http://www.etinc.com/">Emerging Technologies</ulink>
	    is a commercial product.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="bpf-not-configured">
	  <para>Why do I get <errorname>/dev/bpf0: device not
	      configured</errorname>?</para>
	</question>

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

	  <programlisting>device bpf        # Berkeley Packet Filter</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="mount-smb-share">
	  <para>How do I mount a disk from a &windows; machine that is
	    on my network, like smbmount in &linux;?</para>
	</question>

	<answer>
	  <para>Use the <application>SMBFS</application> toolset.  It
	    includes a set of kernel modifications and a set of userland
	    programs.  The programs and information are available as
	    &man.mount.smbfs.8; in the base system.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="icmp-response-bw-limit">
	  <para>What are these messages about: <errorname>Limiting
	      icmp/open port/closed port response</errorname> in my log
	    files?</para>
	</question>

	<answer>
	  <para>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:</para>

	  <itemizedlist>
	    <listitem>
	      <para>Brute-force denial of service (DoS) attacks (as
		opposed to single-packet attacks which exploit a
		specific vulnerability).</para>
	    </listitem>

	    <listitem>
	      <para>Port scans which attempt to connect to a large
		number of ports (as opposed to only trying a few
		well-known ports).</para>
	    </listitem>
	  </itemizedlist>

	  <para>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
	    <varname>net.inet.icmp.icmplim</varname> sysctl variable
	    like this, where <literal>300</literal> is the limit in
	    packets per second:</para>

	  <screen>&prompt.root; <userinput>sysctl net.inet.icmp.icmplim=300</userinput></screen>

	  <para>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
	    <varname>net.inet.icmp.icmplim_output</varname> sysctl
	    variable to disable the output like this:</para>

	  <screen>&prompt.root; <userinput>sysctl net.inet.icmp.icmplim_output=0</userinput></screen>

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

      <qandaentry>
	<question id="unknown-hw-addr-format">
	  <para>What are these <errorname>arp: unknown hardware address
	      format</errorname> error messages?</para>
	</question>

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

      <qandaentry>
	<question id="arp-wrong-iface">
	  <para>Why do I keep seeing messages like: <errorname>192.168.0.10 is on
	      fxp1 but got reply from 00:15:17:67:cf:82 on rl0</errorname>, and how do I
	    disable it?</para>
	</question>

	<answer>
	  <para>Because a packet is coming from outside the network
	    unexpectedly.  To disable them, set
	    <varname>net.link.ether.inet.log_arp_wrong_iface</varname>
	    to <literal>0</literal>.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="security">
    <title>Security</title>

    <qandaset>
      <qandaentry>
	<question id="sandbox">
	  <para>What is a sandbox?</para>
	</question>
	<answer>
	  <para><quote>Sandbox</quote> is a security term.  It can mean
	    two things:</para>

	  <itemizedlist>
	    <listitem>
	      <para>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.</para>

	      <para>The process is said to be able to
		<quote>play</quote> 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.</para>

	      <para>The walls might be a user&nbsp;ID, for example.
		This is the definition used in the &man.security.7; and
		&man.named.8; man pages.</para>

	      <para>Take the <literal>ntalk</literal> service, for
		example (see &man.inetd.8;).  This service used to run
		as user&nbsp;ID <username>root</username>.  Now it runs
		as user&nbsp;ID <username>tty</username>.  The
		<username>tty</username> user is a sandbox designed to
		make it more difficult for someone who has successfully
		hacked into the system via <literal>ntalk</literal> from
		being able to hack beyond that user&nbsp;ID.</para>
	    </listitem>

	    <listitem>
	      <para>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.</para>

	      <para>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., <filename
		  class="directory">/</filename> for that process is this
		directory, not the real <filename
		  class="directory">/</filename> of the system).</para>

	      <para>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 &mdash; other processes in the system
		do not, necessarily.</para>

	      <para>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.</para>
	    </listitem>
	  </itemizedlist>

	  <para>&unix; implements two core sandboxes.  One is at the
	    process level, and one is at the userid level.</para>

	  <para>Every &unix; process is completely firewalled off from
	    every other &unix; process.  One process cannot modify the
	    address space of another.</para>

	  <para>A &unix; process is owned by a particular userid.  If
	    the user&nbsp;ID is not the <username>root</username> user,
	    it serves to firewall the process off from processes owned
	    by other users.  The user&nbsp;ID is also used to firewall
	    off on-disk data.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="securelevel">
	  <para>What is securelevel?</para>
	</question>

	<answer>
	  <para><literal>securelevel</literal> is a security
	    mechanism implemented in the kernel.  When the securelevel
	    is positive, the
	    kernel restricts certain tasks; not even the superuser
	    (i.e., <username>root</username>) is allowed to do them.
	    The securelevel mechanism limits the ability to:</para>

	  <itemizedlist>
	    <listitem>
	      <para>Unset certain file flags, such as
		<literal>schg</literal> (the system immutable
		flag).</para>
	    </listitem>

	    <listitem>
	      <para>Write to kernel memory via
		<devicename>/dev/mem</devicename> and
		<devicename>/dev/kmem</devicename>.</para>
	    </listitem>

	    <listitem>
	      <para>Load kernel modules.</para>
	    </listitem>

	    <listitem>
	      <para>Alter firewall rules.</para>
	    </listitem>
	  </itemizedlist>

	  <para>To check the status of the securelevel on a running
	    system, simply execute the following command:</para>

	  <screen>&prompt.root; <userinput>sysctl -n kern.securelevel</userinput></screen>

	  <para>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.</para>

	  <para>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 <maketarget>installworld</maketarget>
	    or changing the date), you will have to change the
	    securelevel setting in <filename>/etc/rc.conf</filename>
	    (you want to look for the
	    <varname>kern_securelevel</varname> and
	    <varname>kern_securelevel_enable</varname> variables) and
	    reboot.</para>

	  <para>For more information on securelevel and the specific
	    things all the levels do, please consult the &man.init.8;
	    manual page.</para>

	  <warning>
	    <para>Securelevel is not a silver bullet; it has many known
	      deficiencies.  More often than not, it provides a false
	      sense of security.</para>

	    <para>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.</para>

	    <para>This point and others are often discussed on the
	      mailing lists, particularly the &a.security;.  Please
	      search the archives <ulink
		url="&url.base;/search/index.html">here</ulink> for an
	      extensive discussion.  A more fine-grained mechanism
	      is preferred.</para>
	  </warning>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="extra-named-port">
	  <para>BIND (<command>named</command>) is listening on
	    some high-numbered ports.  What is going on?</para>
	</question>

	<answer>
	  <para>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
	    <literal>avoid-v4-udp-ports</literal> and
	    <literal>avoid-v6-udp-ports</literal> options to avoid
	    selecting random port numbers within a blocked range.</para>

	  <warning>
	    <para>If a port number (like 53) is specified via the
	      <literal>query-source</literal> or
	      <literal>query-source-v6</literal> options in
	      <filename>/etc/namedb/named.conf</filename>, randomized
	      port selection will not be used.  It is strongly
	      recommended that these options not be used to specify
	      fixed port numbers.</para>
	  </warning>

	  <para>Congratulations, by the way.  It is good practice to
	    read your &man.sockstat.1; output and notice odd
	    things!</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="sendmail-port-587">
	  <para>The <application>sendmail</application> daemon is
	    listening on port 587 as well as the standard port 25!  What
	    is going on?</para>
	</question>

	<answer>
	  <para>Recent versions of <application>sendmail</application>
	    support a mail submission feature that runs over port 587.
	    This is not yet widely supported, but is growing in
	    popularity.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="toor-account">
	  <para>What is this UID 0 <username>toor</username> account?
	    Have I been compromised?</para>
	</question>

	<answer>
	  <para>Do not worry.  <username>toor</username> is an
	    <quote>alternative</quote> superuser account (toor is root
	    spelt backwards).  Previously it was created when the
	    &man.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
	    <username>root</username>'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
	    <filename class="directory">/usr/local/bin</filename> which, by default,
	    resides on a different file system.  If
	    <username>root</username>'s shell is located in
	    <filename class="directory">/usr/local/bin</filename> and
	    <filename class="directory">/usr</filename> (or whatever file system contains
	    <filename class="directory">/usr/local/bin</filename>) is not mounted for some
	    reason, <username>root</username> 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).</para>

	  <para>Some people use <username>toor</username> for day-to-day
	    <username>root</username> tasks with a non-standard shell,
	    leaving <username>root</username>, with a standard shell,
	    for single user mode or emergencies.  By default you cannot
	    log in using <username>toor</username> as it does not have a
	    password, so log in as <username>root</username> and set a
	    password for <username>toor</username> if you want to use
	    it.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="ppp">
    <title>PPP</title>

    <qandaset>
      <qandaentry>
	<question id="userppp">
	  <para>I cannot make &man.ppp.8; work.  What am I doing
	    wrong?</para>
	</question>

	<answer>
	  <para>You should first read the &man.ppp.8; manual page and
	    the <ulink
	      url="&url.books.handbook;/ppp-and-slip.html#userppp">PPP section of the handbook</ulink>.
	    Enable logging with the following command:</para>

	  <programlisting>set log Phase Chat Connect Carrier lcp ipcp ccp command</programlisting>

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

	  <programlisting>!ppp
*.*        /var/log/ppp.log</programlisting>

	  <para>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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-hangs">
	  <para>Why does &man.ppp.8; hang when I run it?</para>
	</question>

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

	  <programlisting>127.0.0.1        foo.example.com foo localhost</programlisting>

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

	  <para>You should be able to successfully
	    <command>ping -c1 `hostname`</command> when you are
	    done.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-nodial-auto">
	  <para>Why will &man.ppp.8; not dial in
	    <literal>-auto</literal> mode?</para>
	</question>

	<answer>
	  <para>First, check that you have got a default route.  By
	    running <command>netstat -rn</command> (see
	    &man.netstat.1;), you should see two entries like
	    this:</para>

	  <programlisting>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</programlisting>

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

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

	  <programlisting>delete ALL</programlisting>

	  <para>If this is the case, go back to the <ulink
	      url="&url.books.handbook;/userppp.html#userppp-final">Final System Configuration</ulink>
	    section of the handbook.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="no-route-to-host">
	  <para>What does <errorname>No route to host</errorname>
	    mean?</para>
	</question>

	<answer>
	  <para>This error is usually due that the following section is
	    missing in your <filename>/etc/ppp/ppp.linkup</filename>:</para>

	  <programlisting>MYADDR:
  delete ALL
  add 0 0 HISADDR</programlisting>

	  <para>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 <literal>packet mode</literal> (packet mode is
	    indicated by the capitalized <acronym>PPP</acronym> in the
	    prompt):</para>

	  <programlisting>delete ALL
add 0 0 HISADDR</programlisting>

	  <para>Refer to the <ulink
	      url="&url.books.handbook;/userppp.html#userppp-dynamicip">PPP and Dynamic IP addresses</ulink>
	    section of the handbook for further details.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="connection-threeminutedrop">
	  <para>Why does my connection drop after about 3
	    minutes?</para>
	</question>

	<answer>
	  <para>The default PPP timeout is 3 minutes.  This can be
	    adjusted with the following line:</para>

	  <programlisting>set timeout <replaceable>NNN</replaceable></programlisting>

	  <para>where <replaceable>NNN</replaceable> is the number of
	    seconds of inactivity before the connection is closed.  If
	    <replaceable>NNN</replaceable> is zero, the connection is
	    never closed due to a timeout.  It is possible to put this
	    command in <filename>ppp.conf</filename>, 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 <application>ppp</application>'s server socket
	    using &man.telnet.1; or &man.pppctl.8;.  Refer to the
	    &man.ppp.8; man page for further details.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-drop-heavy-load">
	  <para>Why does my connection drop under heavy load?</para>
	</question>

	<answer>
	  <para>If you have Link Quality Reporting (LQR) configured, it
	    is possible that too many LQR packets are lost between your
	    machine and the peer.  &man.ppp.8; deduces that
	    the line must therefore be bad, and disconnects.
	    LQR is disabled by default and can be enabled with the
	    following line:</para>

	  <programlisting>enable lqr</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-drop-random">
	  <para>Why does my connection drop after a random amount of
	    time?</para>
	</question>

	<answer>
	  <para>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.</para>

	  <para>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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-hangs-random">
	  <para>Why does my connection hang after a random amount of
	    time?</para>
	</question>

	<answer>
	  <para>Many people experience hung connections with no apparent
	    explanation.  The first thing to establish is which side of
	    the link is hung.</para>

	  <para>If you are using an external modem, you can simply try
	    using &man.ping.8; to see if the <acronym>TD</acronym> light
	    is flashing when you transmit data.  If it flashes (and the
	    <acronym>RD</acronym> light does not), the problem is with
	    the remote end.  If <acronym>TD</acronym> does not flash,
	    the problem is local.  With an internal modem, you will need
	    to use the <literal>set server</literal> command in
	    <filename>ppp.conf</filename>.  When the hang occurs,
	    connect to &man.ppp.8; using &man.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 <literal>set socket</literal> command
	    succeeded at startup time), the problem is local.  If you
	    can connect and things are still hung, enable local async
	    logging with <literal>set log local async</literal> and use
	    &man.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.</para>

	  <para>Having established whether the problem is local or
	    remote, you now have two possibilities:</para>

	  <itemizedlist>
	    <listitem>
	      <para>If the problem is remote, read on entry <xref
		  linkend="ppp-remote-not-responding"/>.</para>
	    </listitem>

	    <listitem>
	      <para>If the problem is local, read on entry <xref
		  linkend="ppp-hung"/>.</para>
	    </listitem>
	  </itemizedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-remote-not-responding">
	  <para>The remote end is not responding.  What can I do?</para>
	</question>

	<answer>
	  <para>There is very little you can do about this.  Most ISPs
	    will refuse to help if you are not running a &microsoft; OS.
	    You can <literal>enable lqr</literal> in your
	    <filename>ppp.conf</filename>, allowing &man.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.</para>

	  <para>First, try disabling all local compression by adding the
	    following to your configuration:</para>

	  <programlisting>disable pred1 deflate deflate24 protocomp acfcomp shortseq vj
deny pred1 deflate deflate24 protocomp acfcomp shortseq vj</programlisting>

	  <para>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).</para>

	  <para>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 (<errorname>Memory fault</errorname>,
	    <errorname>Core dumped</errorname>).</para>

	  <para>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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-hung">
	  <para>&man.ppp.8; has hung.  What can I do?</para>
	</question>

	<answer>
	  <para>Your best bet here is to rebuild &man.ppp.8; with
	    debugging information, and then use &man.gdb.1; to grab a
	    stack trace from the <application>ppp</application> process
	    that is stuck.  To rebuild the
	    <application>ppp</application> utility with debugging
	    information, you can type:</para>

	  <screen>&prompt.root; <userinput>cd /usr/src/usr.sbin/ppp</userinput>
&prompt.root; <userinput>env DEBUG_FLAGS='-g' make clean</userinput>
&prompt.root; <userinput>env DEBUG_FLAGS='-g' make install</userinput></screen>

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

	  <screen>&prompt.root; <userinput>gdb ppp `pgrep ppp`</userinput></screen>

	  <para>At the <application>gdb</application> prompt, you can
	    use the <command>bt</command> or <command>where</command>
	    commands to get a stack trace.  Save the output of your
	    <application>gdb</application> session, and
	    <quote>detach</quote> from the running process by typing
	    <command>quit</command>.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-same-magic">
	  <para>I keep seeing errors about magic being the same.  What
	    does it mean?</para>
	</question>

	<answer>
	  <para>Occasionally, just after connecting, you may see
	    messages in the log that say <errorname>Magic is
	      same</errorname>.  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
	    &man.ppp.8; eventually gives up and closes the
	    connection.</para>

	  <para>This normally happens on server machines with slow disks
	    that are spawning a &man.getty.8; on the port, and executing
	    &man.ppp.8; from a login script or program after login.
	    There were reports of it happening consistently when using
	    slirp.  The reason is that in the time taken between
	    &man.getty.8; exiting and &man.ppp.8; starting, the
	    client-side &man.ppp.8; starts sending Line Control Protocol
	    (LCP) packets.  Because ECHO is still switched on for the
	    port on the server, the client &man.ppp.8; sees these
	    packets <quote>reflect</quote> back.</para>

	  <para>One part of the LCP negotiation is to establish a magic
	    number for each side of the link so that
	    <quote>reflections</quote> can be detected.  The protocol
	    says that when the peer tries to negotiate the same magic
	    number, a NAK should be sent and a new magic number should
	    be chosen.  During the period that the server port has ECHO
	    turned on, the client &man.ppp.8; sends LCP packets, sees
	    the same magic in the reflected packet and NAKs it.  It also
	    sees the NAK reflect (which also means &man.ppp.8; must
	    change its magic).  This produces a potentially enormous
	    number of magic number changes, all of which are happily
	    piling into the server's tty buffer.  As soon as &man.ppp.8;
	    starts on the server, it is flooded with magic number
	    changes and almost immediately decides it has tried enough
	    to negotiate LCP and gives up.  Meanwhile, the client, who
	    no longer sees the reflections, becomes happy just in time
	    to see a hangup from the server.</para>

	  <para>This can be avoided by allowing the peer to start
	    negotiating with the following line in
	    <filename>ppp.conf</filename>:</para>

	  <programlisting>set openmode passive</programlisting>

	  <para>This tells &man.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:</para>

	  <programlisting>set openmode active 3</programlisting>

	  <para>This tells &man.ppp.8; to be passive for 3 seconds, and
	    then to start sending LCP requests.  If the peer starts
	    sending requests during this period, &man.ppp.8; will
	    immediately respond rather than waiting for the full 3
	    second period.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-lcp-constant">
	  <para>LCP negotiations continue until the connection is
	    closed.  What is wrong?</para>
	</question>

	<answer>
	  <para>There is currently an implementation mis-feature in
	    &man.ppp.8; where it does not associate LCP, CCP &amp; 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.</para>

	  <para>Consider two implementations, <hostid>A</hostid> and
	    <hostid>B</hostid>.  <hostid>A</hostid> starts sending LCP
	    requests immediately after connecting and <hostid>B</hostid>
	    takes 7 seconds to start.  When <hostid>B</hostid> starts,
	    <hostid>A</hostid> 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.
	    <hostid>B</hostid> sends a REQ, then an ACK to the first of
	    <hostid>A</hostid>'s REQs.  This results in
	    <hostid>A</hostid> entering the <acronym>OPENED</acronym>
	    state and sending and ACK (the first) back to
	    <hostid>B</hostid>.  In the meantime, <hostid>B</hostid>
	    sends back two more ACKs in response to the two additional
	    REQs sent by <hostid>A</hostid> before <hostid>B</hostid>
	    started up.  <hostid>B</hostid> then receives the first ACK
	    from <hostid>A</hostid> and enters the
	    <acronym>OPENED</acronym> state.  <hostid>A</hostid>
	    receives the second ACK from <hostid>B</hostid> and goes
	    back to the <acronym>REQ-SENT</acronym> state, sending
	    another (forth) REQ as per the RFC.  It then receives the
	    third ACK and enters the <acronym>OPENED</acronym> state.
	    In the meantime, <hostid>B</hostid> receives the forth REQ
	    from <hostid>A</hostid>, resulting in it reverting to the
	    <acronym>ACK-SENT</acronym> state and sending another
	    (second) REQ and (forth) ACK as per the RFC.
	    <hostid>A</hostid> gets the REQ, goes into
	    <acronym>REQ-SENT</acronym> and sends another REQ.  It
	    immediately receives the following ACK and enters
	    <acronym>OPENED</acronym>.</para>

	  <para>This goes on until one side figures out that they are
	    getting nowhere and gives up.</para>

	  <para>The best way to avoid this is to configure one side to
	    be <literal>passive</literal> &mdash; that is, make one side
	    wait for the other to start negotiating.  This can be done
	    with the following command:</para>

	  <programlisting>set openmode passive</programlisting>

	  <para>Care should be taken with this option.  You should also
	    use this command to limit the amount of time that
	    &man.ppp.8; waits for the peer to begin negotiations:</para>

	  <programlisting>set stopped <replaceable>N</replaceable></programlisting>

	  <para>Alternatively, the following command (where
	    <replaceable>N</replaceable> is the number of seconds to
	    wait before starting negotiations) can be used:</para>

	  <programlisting>set openmode active <replaceable>N</replaceable></programlisting>

	  <para>Check the manual page for details.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-shell-test-lockup">
	  <para>Why does &man.ppp.8; lock up when I shell out to test
	    it?</para>
	</question>

	<answer>
	  <para>When you execute the <command>shell</command> or
	    <command>!</command> command, &man.ppp.8; executes a shell
	    (or if you have passed any arguments, &man.ppp.8; will
	    execute those arguments).  The
	    <application>ppp</application> 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 &man.ppp.8; is
	    waiting for the command to complete.</para>

	  <para>To execute commands like this, use
	    <command>!bg</command> instead.  This will execute
	    the given command in the background, and &man.ppp.8; can
	    continue to service the link.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-null-modem">
	  <para>Why does &man.ppp.8; over a null-modem cable never
	    exit?</para>
	</question>

	<answer>
	  <para>There is no way for &man.ppp.8; to automatically
	    determine that a direct connection has been dropped.  This
	    is due to the lines that are used in a null-modem serial
	    cable.  When using this sort of connection, LQR should
	    always be enabled with the following line:</para>

	  <programlisting>enable lqr</programlisting>

	  <para>LQR is accepted by default if negotiated by the
	    peer.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-auto-noreasondial">
	  <para>Why does &man.ppp.8; dial for no reason in
	    <option>-auto</option> mode?</para>
	</question>

	<answer>
	  <para>If &man.ppp.8; is dialing unexpectedly, you must
	    determine the cause, and set up Dial filters (dfilters) to
	    prevent such dialing.</para>

	  <para>To determine the cause, use the following line:</para>

	  <programlisting>set log +tcp/ip</programlisting>

	  <para>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.</para>

	  <para>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 <emphasis>not</emphasis> prevent &man.ppp.8; from
	    passing the packets through an established connection), use
	    the following:</para>

	  <programlisting>set dfilter 1 deny udp src eq 53
set dfilter 2 deny udp dst eq 53
set dfilter 3 permit 0/0 0/0</programlisting>

	  <para>This is not always suitable, as it will effectively
	    break your demand-dial capabilities &mdash; most programs
	    will need a DNS lookup before doing any other network
	    related things.</para>

	  <para>In the DNS case, you should try to determine what is
	    actually trying to resolve a host name.  A lot of the time,
	    &man.sendmail.8; is the culprit.  You should make sure that
	    you tell <application>sendmail</application> not to do any
	    DNS lookups in its configuration file.  See the section on
	    <ulink
	      url="&url.books.handbook;/smtp-dialup.html">using email with a dialup connection</ulink>
	    in the &os; 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
	    <filename>.mc</filename>:</para>

	  <programlisting>define(`confDELIVERY_MODE', `d')dnl</programlisting>

	  <para>This will make <application>sendmail</application> queue
	    everything until the queue is run (usually, sendmail is
	    run with <option>-bd -q30m</option>, telling it to run
	    the queue every 30 minutes) or until a <command>sendmail
	      <option>-q</option></command> is done (perhaps from your
	    <filename>ppp.linkup</filename>).</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ccp-errors">
	  <para>What do these CCP errors mean?</para>
	</question>

	<answer>
	  <para>I keep seeing the following errors in my log
	    file:</para>

	  <programlisting>CCP: CcpSendConfigReq
CCP: Received Terminate Ack (1) state = Req-Sent (6)</programlisting>

	  <para>This is because &man.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:</para>

	  <programlisting>disable pred1</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-connectionspeed">
	  <para>Why does &man.ppp.8; not log my connection speed?</para>
	</question>

	<answer>
	  <para>To log all lines of your modem
	    <quote>conversation</quote>, you must enable the
	    following:</para>

	  <programlisting>set log +connect</programlisting>

	  <para>This will make &man.ppp.8; log everything up until the
	    last requested <quote>expect</quote> string.</para>

	  <para>If you wish to see your connect speed and are using PAP
	    or CHAP (and therefore do not have anything to
	    <quote>chat</quote> after the CONNECT in the dial script
	    &mdash; no <literal>set login</literal> script), you must
	    make sure that you instruct &man.ppp.8; to
	    <quote>expect</quote> the whole CONNECT line, something like
	    this:</para>

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

	  <para>Here, we get our CONNECT, send nothing, then expect a
	    line-feed, forcing &man.ppp.8; to read the whole CONNECT
	    response.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-ignores-backslash">
	  <para>Why does &man.ppp.8; ignore the <literal>\</literal>
	    character in my chat script?</para>
	</question>

	<answer>
	  <para>The <application>ppp</application> utility parses each
	    line in your config files so that it can interpret strings
	    such as <literal>set phone "123 456 789"</literal> correctly
	    and realize that the number is actually only
	    <emphasis>one</emphasis> argument.  To specify a
	    <literal>&quot;</literal> character, you must escape it
	    using a backslash (<literal>\</literal>).</para>

	  <para>When the chat interpreter parses each argument, it
	    re-interprets the argument to find any special
	    escape sequences such as <literal>\P</literal> or
	    <literal>\T</literal> (see the manual page).  As a result of
	    this double-parsing, you must remember to use the correct
	    number of escapes.</para>

	  <para>If you wish to actually send a <literal>\</literal>
	    character to (say) your modem, you would need something
	    like:</para>

	  <programlisting>set dial "\"\" ATZ OK-ATZ-OK AT\\\\X OK"</programlisting>

	  <para>It will result in the following sequence:</para>

	  <programlisting>ATZ
OK
AT\X
OK</programlisting>

	  <para>Or:</para>

	  <programlisting>set phone 1234567
set dial "\"\" ATZ OK ATDT\\T"</programlisting>

	  <para>It will result in the following sequence:</para>

	  <programlisting>ATZ
OK
ATDT1234567</programlisting>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-segfault-nocore">
	  <para>Why does &man.ppp.8; get a <errorname>Segmentation
	      fault</errorname>, but I see no
	    <filename>ppp.core</filename></para>
	</question>

	<answer>
	  <para>The <application>ppp</application> utility (or any other
	    program for that matter) should never dump core.  Because
	    &man.ppp.8; runs setuid (with an effective user&nbsp;ID of
	    <literal>0</literal>), the operating system will not write
	    core image of &man.ppp.8; to disk before terminating it.
	    If, however &man.ppp.8; is actually terminating due to a
	    segmentation violation or some other signal that normally
	    causes core to be dumped, <emphasis>and</emphasis> 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:</para>

	  <screen>&prompt.root; <userinput><command>cd</command> <filename class="directory">/usr/src/usr.sbin/ppp</filename></userinput>
&prompt.root; <userinput><command>echo</command> <makevar>STRIP</makevar>= &gt;&gt; <filename>/etc/make.conf</filename></userinput>
&prompt.root; <userinput><command>echo</command> <makevar>CFLAGS</makevar>+=<option>-g</option> &gt;&gt; <filename>/etc/make.conf</filename></userinput>
&prompt.root; <userinput><command>make</command> <maketarget>install</maketarget> <maketarget>clean</maketarget></userinput></screen>

	  <para>You will now have a debuggable version of &man.ppp.8;
	    installed.  You will have to be <username>root</username> to
	    run &man.ppp.8; as all of its privileges have been revoked.
	    When you start &man.ppp.8;, take a careful note of what your
	    current directory was at the time.</para>

	  <para>Now, if and when &man.ppp.8; receives the segmentation
	    violation, it will dump a core file called
	    <filename>ppp.core</filename>.  You should then do the
	    following:</para>

	  <screen>&prompt.user; <userinput>su</userinput>
&prompt.root; <userinput>gdb /usr/sbin/ppp ppp.core</userinput>
<prompt>(gdb)</prompt> <userinput>bt</userinput>
.....
<prompt>(gdb)</prompt> <userinput>f 0</userinput>
....
<prompt>(gdb)</prompt> <userinput>i args</userinput>
....
<prompt>(gdb)</prompt> <userinput>l</userinput>
.....</screen>

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

	  <para>If you are familiar with &man.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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-autodialprocess-noconnect">
	  <para>Why does the process that forces a dial in
	    <option>-auto</option> mode never connect?</para>
	</question>

	<answer>
	  <para>This was a known problem with &man.ppp.8; set up to
	    negotiate a dynamic local IP number with the peer in
	    <option>-auto</option> mode.  It has been fixed a long time
	    ago &mdash; search the manual page for
	    <literal>iface</literal>.</para>

	  <para>The problem was that when that initial program calls
	    &man.connect.2;, the IP number of the &man.tun.4; interface
	    is assigned to the socket endpoint.  The kernel creates the
	    first outgoing packet and writes it to the &man.tun.4;
	    device.  &man.ppp.8; then reads the packet and establishes a
	    connection.  If, as a result of &man.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.</para>

	  <para>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
	    &man.ppp.8; does this, but most other implementations do
	    not.</para>

	  <para>The easiest method from our side would be to never
	    change the &man.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
	    <literal>iface-alias</literal> option in the latest version
	    of &man.ppp.8; is doing (with the help of &man.libalias.3;
	    and &man.ppp.8;'s <option>-nat</option> switch) &mdash; it
	    is maintaining all previous interface addresses and NATing
	    them to the last negotiated address.</para>

	  <para>Another alternative (and probably the most reliable)
	    would be to implement a system call that changes all bound
	    sockets from one IP to another.  &man.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 <acronym>DHCP</acronym> clients when they are forced
	    to call the <function>bind()</function> function for their
	    sockets.</para>

	  <para>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 <hostid
	      role="ipaddr">255.255.255.255</hostid> up until the first
	    <literal>SIOCAIFADDR</literal> &man.ioctl.2; is done.  This
	    would result in fully binding the socket.  It would be up to
	    &man.ppp.8; to change the source IP number, but only if it
	    is set to <hostid role="ipaddr">255.255.255.255</hostid>,
	    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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="ppp-nat-games">
	  <para>Why do most games not work with the
	    <option>-nat</option> switch?</para>
	</question>

	<answer>
	  <para>The reason games and the like do not work when
	    &man.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.</para>

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

	  <para>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
	    <filename>/etc/ppp/ppp.conf</filename> will make the
	    software functional:</para>

	  <programlisting>nat port <replaceable>proto</replaceable> <replaceable>internalmachine</replaceable>:<replaceable>port</replaceable> <replaceable>port</replaceable></programlisting>

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

	  <para>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 &mdash; after all, the outside world is seeing
	    your entire internal network as being just a single
	    machine.</para>

	  <para>If the port numbers are not consistent, there are three
	    more options:</para>

	  <orderedlist>
	    <listitem>
	      <para>Submit support in &man.libalias.3;.  Examples of
		<quote>special cases</quote> can be found in
		<filename>/usr/src/sys/netinet/libalias/alias_*.c</filename>
		(<filename>alias_ftp.c</filename> 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 <quote>route</quote> in the alias table so that the
		subsequent packets know where to go.</para>

	      <para>This is the most difficult solution, but it is the
		best and will make the software work with multiple
		machines.</para>
	    </listitem>

	    <listitem>
	      <para>Use a proxy.  The application may support
		<literal>socks5</literal> for example, or
		may have a
		<quote>passive</quote> option that avoids ever
		requesting that the peer open connections back to the
		local machine.</para>
	    </listitem>

	    <listitem>
	      <para>Redirect everything to the internal machine using
		<literal>nat addr</literal>.  This is the sledge-hammer
		approach.</para>
	    </listitem>
	  </orderedlist>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="fcs-errors">
	  <para>What are FCS errors?</para>
	</question>

	<answer>
	  <para>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 <literal>show hdlc</literal>
	    command.</para>

	  <para>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 &mdash; this may eradicate the
	    problem.</para>

	  <para>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
	    <emphasis>must</emphasis> use software flow control, use the
	    command <literal>set accmap 0x000a0000</literal> to tell
	    &man.ppp.8; to escape the <literal>^Q</literal> and
	    <literal>^S</literal> characters.</para>

	  <para>Another reason for seeing too many FCS errors may be
	    that the remote end has stopped talking
	    <acronym>PPP</acronym>.  You may want to enable
	    <literal>async</literal> 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 &man.ppp.8; without dropping the line by using
	    <command>close lcp</command> (a following
	    <command>term</command>) will reconnect you to the
	    shell on the remote machine.</para>

	  <para>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.</para>
	</answer>
      </qandaentry>

      <qandaentry>
	<question id="desperation">
	  <para>None of this helps &mdash; I am desperate!  What can I
	    do?</para>
	</question>

	<answer>
	  <para>If all else fails, send as much information as you can,
	    including your config files, how you are starting
	    &man.ppp.8;, the relevant parts of your log file and the
	    output of <command>netstat -rn</command> (before
	    and after connecting) to the &a.questions;
	    and someone should point you in the right
	    direction.</para>
	</answer>
      </qandaentry>
    </qandaset>
  </chapter>

  <chapter id="serial">
    <title>Serial Communications</title>

    <para>This section answers common questions about serial
      communications with &os;.  PPP is covered in the <link
	linkend="networking">Networking</link> section.</para>

    <qandaset>
      <qandaentry>
	<question id="multiport-serial-support">
	  <para>Which multi-port serial cards are supported by
	    &os;?</para>
	</question>

	<answer>