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 <!--
      The FreeBSD Documentation Project
 
      $FreeBSD$
 -->
 
 <chapter id="network-servers">
   <chapterinfo>
     <authorgroup>
       <author>
         <firstname>Murray</firstname>
 	<surname>Stokely</surname>
 	<contrib>Reorganized by </contrib>
       </author>
     </authorgroup>
     <!-- 23 July 2004 -->
   </chapterinfo>
 
   <title>Network Servers</title>
 
   <sect1 id="network-servers-synopsis">
     <title>Synopsis</title>
 
     <para>This chapter will cover some of the more frequently used
       network services on &unix; systems.  We will cover how to
       install, configure, test, and maintain many different types of
       network services.  Example configuration files are included
       throughout this chapter for you to benefit from.</para>
 
     <para>After reading this chapter, you will know:</para>
 
     <itemizedlist>
 
       <listitem>
 	<para>How to manage the <application>inetd</application>
 	  daemon.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up a network file system.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up a network information server for sharing
 	  user accounts.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up automatic network settings using DHCP.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up a domain name server.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up the <application>Apache</application> HTTP Server.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up a File Transfer Protocol (FTP) Server.</para>
       </listitem>
 
       <listitem>
 	<para>How to set up a file and print server for &windows;
 	  clients using <application>Samba</application>.</para>
       </listitem>
 
       <listitem>
 	<para>How to synchronize the time and date, and set up a
 	  time server, with the NTP protocol.</para>
       </listitem>
 
     </itemizedlist>
 
     <para>Before reading this chapter, you should:</para>
 
     <itemizedlist>
       <listitem>
 	<para>Understand the basics of the
 	  <filename>/etc/rc</filename> scripts.</para>
       </listitem>
 
       <listitem>
 	<para>Be familiar with basic network terminology.</para>
       </listitem>
 
       <listitem>
       <para>Know how to install additional third-party
         software (<xref linkend="ports">).</para>
       </listitem>
 
     </itemizedlist>
   </sect1>
 
   <sect1 id="network-inetd">
     <sect1info>
       <authorgroup>
         <author>
           <firstname>Chern</firstname>
           <surname>Lee</surname>
           <contrib>Contributed by </contrib>
         </author>
       </authorgroup>
       <authorgroup>
 	<author>
 	  <contrib>Updated for &os; 6.1-RELEASE by </contrib>
 	  <othername>The &os; Documentation Project</othername>
 	</author>
       </authorgroup>
     </sect1info>
 
     <title>The <application>inetd</application> <quote>Super-Server</quote></title>
 
     <sect2 id="network-inetd-overview">
       <title>Overview</title>
 
       <para>&man.inetd.8; is sometimes referred to as the <quote>Internet
 	Super-Server</quote> because it manages connections for
 	several services.  When a
 	connection is received by <application>inetd</application>, it
 	determines which program the connection is destined for, spawns
 	the particular process and delegates the socket to it (the program
 	is invoked with the service socket as its standard input, output
 	and error descriptors).  Running
 	<application>inetd</application> for servers that are not heavily used can reduce the
 	overall system load, when compared to running each daemon
 	individually in stand-alone mode.</para>
 
       <para>Primarily, <application>inetd</application> is used to
 	spawn other daemons, but several trivial protocols are handled
 	directly, such as <application>chargen</application>,
 	<application>auth</application>, and
 	<application>daytime</application>.</para>
 
       <para>This section will cover the basics in configuring
 	<application>inetd</application> through its command-line
 	options and its configuration file,
 	<filename>/etc/inetd.conf</filename>.</para>
     </sect2>
 
     <sect2 id="network-inetd-settings">
       <title>Settings</title>
 
       <para><application>inetd</application> is initialized through
 	the &man.rc.8; system.  The
 	<literal>inetd_enable</literal> option is set to
 	<literal>NO</literal> by default, but may be turned on
 	by <application>sysinstall</application> during installation,
 	depending on the configuration chosen by the user.
 	Placing:
 	<programlisting>inetd_enable="YES"</programlisting> or
 	<programlisting>inetd_enable="NO"</programlisting> into
 	<filename>/etc/rc.conf</filename> will enable or disable
 	<application>inetd</application> starting at boot time.
 	The command:
 	<programlisting>/etc/rc.d/inetd rcvar</programlisting>
 	can be run to display the current effective setting.</para>
 
       <para>Additionally, different command-line options can be passed
 	to <application>inetd</application> via the
 	<literal>inetd_flags</literal> option.</para>
     </sect2>
 
     <sect2 id="network-inetd-cmdline">
       <title>Command-Line Options</title>
 
       <para>Like most server daemons, <application>inetd</application>
 	has a number of options that it can be passed in order to
 	modify its behaviour.  The full list of options reads:</para>
 
       <para><command>inetd</command> <option>[-d] [-l] [-w] [-W] [-c maximum] [-C rate] [-a address | hostname]
            [-p filename] [-R rate] [-s maximum] [configuration file]</option></para>
 
       <para>Options can be passed to <application>inetd</application> using the
 	<literal>inetd_flags</literal> option in
 	<filename>/etc/rc.conf</filename>.  By default,
 	<literal>inetd_flags</literal> is set to
 	<literal>-wW -C 60</literal>, which turns on TCP wrapping for
 	<application>inetd</application>'s services, and prevents any
 	single IP address from requesting any service more than 60 times
 	in any given minute.</para>
 
       <para>Novice users may be pleased to note that
 	these parameters usually do not need to be modified,
 	although we mention the rate-limiting options below as
 	they be useful should you find that you are receiving an
 	excessive amount of connections.  A full list of options
 	can be found in the &man.inetd.8; manual.</para>
 
       <variablelist>
 	<varlistentry>
 	  <term>-c maximum</term>
 
 	  <listitem>
 	    <para>Specify the default maximum number of simultaneous
 	      invocations of each service; the default is unlimited.
 	      May be overridden on a per-service basis with the
 	      <option>max-child</option> parameter.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>-C rate</term>
 
 	  <listitem>
 	    <para>Specify the default maximum number of times a
 	      service can be invoked from a single IP address in one
 	      minute; the default is unlimited.  May be overridden on a
 	      per-service basis with the
 	      <option>max-connections-per-ip-per-minute</option>
 	      parameter.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>-R rate</term>
 
 	  <listitem>
 	    <para>Specify the maximum number of times a service can be
 	      invoked in one minute; the default is 256.  A rate of 0
 	      allows an unlimited number of invocations.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>-s maximum</term>
 
 	  <listitem>
 	    <para>Specify the maximum number of times a service can be
 	      invoked from a single IP address at any one time; the
 	      default is unlimited.  May be overridden on a per-service
 	      basis with the <option>max-child-per-ip</option>
 	      parameter.</para>
 	  </listitem>
 	</varlistentry>
       </variablelist>
     </sect2>
 
     <sect2 id="network-inetd-conf">
       <!-- XXX This section isn't very clear, and could do with some lovin' -->
       <title><filename>inetd.conf</filename></title>
 
       <para>Configuration of <application>inetd</application> is
 	done via the file <filename>/etc/inetd.conf</filename>.</para>
 
       <para>When a modification is made to
 	<filename>/etc/inetd.conf</filename>,
 	<application>inetd</application> can be forced to re-read its
 	configuration file by running the command:</para>
 
       <example id="network-inetd-reread">
 	<title>Reloading the <application>inetd</application>
 	  configuration file</title>
 
 	<screen>&prompt.root; <userinput>/etc/rc.d/inetd reload</userinput></screen>
       </example>
 
       <para>Each line of the configuration file specifies an
 	individual daemon.  Comments in the file are preceded by a
 	<quote>#</quote>.  The format of each entry in
 	<filename>/etc/inetd.conf</filename> is as follows:</para>
 
       <programlisting>service-name
 socket-type
 protocol
 {wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]
 user[:group][/login-class]
 server-program
 server-program-arguments</programlisting>
 
       <para>An example entry for the &man.ftpd.8; daemon
 	using IPv4 might read:</para>
 
       <programlisting>ftp     stream  tcp     nowait  root    /usr/libexec/ftpd       ftpd -l</programlisting>
 
       <variablelist>
 	<varlistentry>
 	  <term>service-name</term>
 
 	  <listitem>
 	    <para>This is the service name of the particular daemon.
 	      It must correspond to a service listed in
 	      <filename>/etc/services</filename>.  This determines
 	      which port <application>inetd</application> must listen
 	      to.  If a new service is being created, it must be
 	      placed in <filename>/etc/services</filename>
 	      first.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>socket-type</term>
 
 	  <listitem>
 	    <para>Either <literal>stream</literal>,
 	      <literal>dgram</literal>, <literal>raw</literal>, or
 	      <literal>seqpacket</literal>.  <literal>stream</literal>
 	      must be used for connection-based, TCP daemons, while
 	      <literal>dgram</literal> is used for daemons utilizing
 	      the <acronym>UDP</acronym> transport protocol.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>protocol</term>
 
 	  <listitem>
 	    <para>One of the following:</para>
 
 	    <informaltable frame="none" pgwide="1">
 	      <tgroup cols="2">
 		<thead>
 		  <row>
 		    <entry>Protocol</entry>
 		    <entry>Explanation</entry>
 		  </row>
 		</thead>
 		<tbody>
 		  <row>
 		    <entry>tcp, tcp4</entry>
 		    <entry>TCP IPv4</entry>
 		  </row>
 		  <row>
 		    <entry>udp, udp4</entry>
 		    <entry>UDP IPv4</entry>
 		  </row>
 		  <row>
 		    <entry>tcp6</entry>
 		    <entry>TCP IPv6</entry>
 		  </row>
 		  <row>
 		    <entry>udp6</entry>
 		    <entry>UDP IPv6</entry>
 		  </row>
 		  <row>
 		    <entry>tcp46</entry>
 		    <entry>Both TCP IPv4 and v6</entry>
 		  </row>
 		  <row>
 		    <entry>udp46</entry>
 		    <entry>Both UDP IPv4 and v6</entry>
 		  </row>
 		</tbody>
 	      </tgroup>
 	    </informaltable>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>{wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]</term>
 
 	  <listitem>
 	    <para><option>wait|nowait</option> indicates whether the
 	      daemon invoked from <application>inetd</application> is
 	      able to handle its own socket or not.
 	      <option>dgram</option> socket types must use the
 	      <option>wait</option> option, while stream socket
 	      daemons, which are usually multi-threaded, should use
 	      <option>nowait</option>.  <option>wait</option> usually
 	      hands off multiple sockets to a single daemon, while
 	      <option>nowait</option> spawns a child daemon for each
 	      new socket.</para>
 
 	    <para>The maximum number of child daemons
 	      <application>inetd</application> may spawn can be set
 	      using the <option>max-child</option> option.  If a limit
 	      of ten instances of a particular daemon is needed, a
 	      <literal>/10</literal> would be placed after
 	      <option>nowait</option>.  Specifying <literal>/0</literal>
 	      allows an unlimited number of children</para>
 
 	    <para>In addition to <option>max-child</option>, two other
 	      options which limit the maximum connections from a single
 	      place to a particular daemon can be enabled.
 	      <option>max-connections-per-ip-per-minute</option> limits
 	      the number of connections from any particular IP address
 	      per minutes, e.g. a value of ten would limit any particular
 	      IP address connecting to a particular service to ten
 	      attempts per minute.  <option>max-child-per-ip</option>
 	      limits the number of children that can be started on
 	      behalf on any single IP address at any moment. These
 	      options are useful to prevent intentional or unintentional
  	      excessive resource consumption and Denial of Service (DoS)
 	      attacks to a machine.</para>
 
 	    <para>In this field, either of <option>wait</option> or
 	      <option>nowait</option> is mandatory.
 	      <option>max-child</option>,
 	      <option>max-connections-per-ip-per-minute</option> and
 	      <option>max-child-per-ip</option> are
 	      optional.</para>
 
 	    <para>A stream-type multi-threaded daemon without any
 	      <option>max-child</option>,
 	      <option>max-connections-per-ip-per-minute</option> or
 	      <option>max-child-per-ip</option> limits
 	      would simply be: <literal>nowait</literal>.</para>
 
 	    <para>The same daemon with a maximum limit of ten daemons
 	      would read: <literal>nowait/10</literal>.</para>
 
 	    <para>The same setup with a limit of twenty
 	      connections per IP address per minute and a maximum
 	      total limit of ten child daemons would read:
 	      <literal>nowait/10/20</literal>.</para>
 
 	    <para>These options are utilized by the default
 	      settings of the &man.fingerd.8; daemon,
 	      as seen here:</para>
 
 	    <programlisting>finger stream  tcp     nowait/3/10 nobody /usr/libexec/fingerd fingerd -s</programlisting>
 
 	    <para>Finally, an example of this field with a maximum of
 	      100 children in total, with a maximum of 5 for any one
 	      IP address would read:
 	      <literal>nowait/100/0/5</literal>.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>user</term>
 
 	  <listitem>
 	    <para>This is the username that the particular daemon
 	      should run as.  Most commonly, daemons run as the
 	      <username>root</username> user.  For security purposes, it is
 	      common to find some servers running as the
 	      <username>daemon</username> user, or the least privileged
 	      <username>nobody</username> user.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>server-program</term>
 
 	  <listitem>
 	    <para>The full path of the daemon to be executed when a
 	      connection is received.  If the daemon is a service
 	      provided by <application>inetd</application> internally,
 	      then <option>internal</option> should be
 	      used.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term>server-program-arguments</term>
 
 	  <listitem>
 	    <para>This works in conjunction with
 	      <option>server-program</option> by specifying the
 	      arguments, starting with <literal>argv[0]</literal>,
 	      passed to the daemon on invocation.  If
 	      <command>mydaemon -d</command> is the command line,
 	      <literal>mydaemon -d</literal> would be the value of
 	      <option>server-program-arguments</option>.  Again, if
 	      the daemon is an internal service, use
 	      <option>internal</option> here.</para>
 	  </listitem>
 	</varlistentry>
       </variablelist>
     </sect2>
 
     <sect2 id="network-inetd-security">
       <title>Security</title>
 
       <para>Depending on the choices made at install time, many
 	of <application>inetd</application>'s services may be enabled
 	by default.  If there is no apparent need for a particular
 	daemon, consider disabling it.  Place a <quote>#</quote> in front of the
 	daemon in question in <filename>/etc/inetd.conf</filename>,
 	and then <link linkend="network-inetd-reread">reload the
 	inetd configuration</link>.  Some daemons, such as
 	<application>fingerd</application>, may not be desired at all
 	because they provide
 	information that may be useful to an attacker.</para>
 
       <para>Some daemons are not security-conscious and have long, or
 	non-existent, timeouts for connection attempts.  This allows an
 	attacker to slowly send connections to a particular daemon,
 	thus saturating available resources.  It may be a good idea to
 	place <option>max-connections-per-ip-per-minute</option>,
 	<option>max-child</option> or <option>max-child-per-ip</option> limitations on certain
 	daemons if you find that you have too many connections.</para>
 
       <para>By default, TCP wrapping is turned on.  Consult the
 	&man.hosts.access.5; manual page for more information on placing
 	TCP restrictions on various <application>inetd</application>
 	invoked daemons.</para>
     </sect2>
 
     <sect2 id="network-inetd-misc">
       <title>Miscellaneous</title>
 
       <para><application>daytime</application>,
 	<application>time</application>,
 	<application>echo</application>,
 	<application>discard</application>,
 	<application>chargen</application>, and
 	<application>auth</application> are all internally provided
 	services of <application>inetd</application>.</para>
 
       <para>The <application>auth</application> service provides
 	identity
 	network services, and is
 	configurable to a certain degree, whilst the others are simply on or off.</para>
 
       <para>Consult the &man.inetd.8; manual page for more in-depth
 	information.</para>
     </sect2>
   </sect1>
 
   <sect1 id="network-nfs">
     <sect1info>
       <authorgroup>
         <author>
           <firstname>Tom</firstname>
           <surname>Rhodes</surname>
           <contrib>Reorganized and enhanced by </contrib>
         </author>
       </authorgroup>
       <authorgroup>
         <author>
           <firstname>Bill</firstname>
       	  <surname>Swingle</surname>
 	  <contrib>Written by </contrib>
         </author>
       </authorgroup>
     </sect1info>
     <title>Network File System (NFS)</title>
 
     <indexterm><primary>NFS</primary></indexterm>
     <para>Among the many different file systems that FreeBSD supports
       is the Network File System, also known as <acronym role="Network
       File System">NFS</acronym>.  <acronym role="Network File
       System">NFS</acronym> allows a system to share directories and
       files with others over a network.  By using <acronym
       role="Network File System">NFS</acronym>, users and programs can
       access files on remote systems almost as if they were local
       files.</para>
 
     <para>Some of the most notable benefits that
       <acronym>NFS</acronym> can provide are:</para>
 
     <itemizedlist>
       <listitem>
 	<para>Local workstations use less disk space because commonly
 	  used data can be stored on a single machine and still remain
 	  accessible to others over the network.</para>
       </listitem>
 
       <listitem>
 	<para>There is no need for users to have separate home
 	  directories on every network machine.  Home directories
 	  could be set up on the <acronym>NFS</acronym> server and
 	  made available throughout the network.</para>
       </listitem>
 
       <listitem>
 	<para>Storage devices such as floppy disks, CDROM drives, and
 	  &iomegazip; drives can be used by other machines on the network.
 	  This may reduce the number of removable media drives
 	  throughout the network.</para>
       </listitem>
     </itemizedlist>
 
     <sect2>
       <title>How <acronym>NFS</acronym> Works</title>
 
       <para><acronym>NFS</acronym> consists of at least two main
         parts: a server and one or more clients.  The client remotely
         accesses the data that is stored on the server machine.  In
         order for this to function properly a few processes have to be
         configured and running.</para>
 
       <para>The server has to be running the following daemons:</para>
       <indexterm>
         <primary>NFS</primary>
         <secondary>server</secondary>
       </indexterm>
       <indexterm>
         <primary>file server</primary>
         <secondary>UNIX clients</secondary>
       </indexterm>
 
       <indexterm>
 	<primary><application>rpcbind</application></primary>
       </indexterm>
       <indexterm>
         <primary><application>mountd</application></primary>
       </indexterm>
       <indexterm>
         <primary><application>nfsd</application></primary>
       </indexterm>
 
       <informaltable frame="none" pgwide="1">
 	<tgroup cols="2">
 	  <colspec colwidth="1*">
 	  <colspec colwidth="3*">
 
 	  <thead>
 	    <row>
 	      <entry>Daemon</entry>
 	      <entry>Description</entry>
 	    </row>
 	  </thead>
 	  <tbody>
 	    <row>
 	      <entry><application>nfsd</application></entry>
 	      <entry>The <acronym>NFS</acronym> daemon which services
 	      requests from the <acronym>NFS</acronym>
 	      clients.</entry>
 	    </row>
 	    <row>
 	      <entry><application>mountd</application></entry>
 	      <entry>The <acronym>NFS</acronym> mount daemon which carries out
 		the requests that &man.nfsd.8; passes on to it.</entry>
 	    </row>
 	    <row>
 	      <entry><application>rpcbind</application></entry>
 	      <entry> This daemon allows
 	      <acronym>NFS</acronym> clients to discover which port
 	      the <acronym>NFS</acronym> server is using.</entry>
 	    </row>
 	  </tbody>
 	</tgroup>
       </informaltable>
 
       <para>The client can also run a daemon, known as
         <application>nfsiod</application>.  The
         <application>nfsiod</application> daemon services the requests
         from the <acronym>NFS</acronym> server.  This is optional, and
         improves performance, but is not required for normal and
         correct operation.  See the &man.nfsiod.8; manual page for
         more information.
       </para>
     </sect2>
 
     <sect2 id="network-configuring-nfs">
       <title>Configuring <acronym>NFS</acronym></title>
       <indexterm>
         <primary>NFS</primary>
         <secondary>configuration</secondary>
       </indexterm>
 
       <para><acronym>NFS</acronym> configuration is a relatively
         straightforward process.  The processes that need to be
         running can all start at boot time with a few modifications to
         your <filename>/etc/rc.conf</filename> file.</para>
 
       <para>On the <acronym>NFS</acronym> server, make sure that the
         following options are configured in the
         <filename>/etc/rc.conf</filename> file:</para>
 
       <programlisting>rpcbind_enable="YES"
 nfs_server_enable="YES"
 mountd_flags="-r"</programlisting>
 
       <para><application>mountd</application> runs automatically
         whenever the <acronym>NFS</acronym> server is enabled.</para>
 
       <para>On the client, make sure this option is present in
         <filename>/etc/rc.conf</filename>:</para>
 
       <programlisting>nfs_client_enable="YES"</programlisting>
 
       <para>The <filename>/etc/exports</filename> file specifies which
         file systems <acronym>NFS</acronym> should export (sometimes
         referred to as <quote>share</quote>).  Each line in
         <filename>/etc/exports</filename> specifies a file system to be
         exported and which machines have access to that file system.
         Along with what machines have access to that file system,
         access options may also be specified.  There are many such
         options that can be used in this file but only a few will be
         mentioned here.  You can easily discover other options by
         reading over the &man.exports.5; manual page.</para>
 
       <para>Here are a few example <filename>/etc/exports</filename>
 	entries:</para>
 
       <indexterm>
         <primary>NFS</primary>
         <secondary>export examples</secondary>
       </indexterm>
 
       <para>The following examples give an idea of how to export
         file systems, although the settings may be different depending
         on your environment and network configuration.  For instance,
         to export the <filename>/cdrom</filename> directory to three
         example machines that have the same domain name as the server
         (hence the lack of a domain name for each) or have entries in
         your <filename>/etc/hosts</filename> file.  The
         <option>-ro</option> flag makes the exported file system
         read-only.  With this flag, the remote system will not be able
         to write any changes to the exported file system.</para>
 
       <programlisting>/cdrom -ro host1 host2 host3</programlisting>
 
       <para>The following line exports <filename>/home</filename> to
 	three hosts by IP address.  This is a useful setup if you have
 	a private network without a <acronym>DNS</acronym> server
 	configured.  Optionally the <filename>/etc/hosts</filename>
 	file could be configured for internal hostnames; please review
 	&man.hosts.5; for more information.  The
 	<option>-alldirs</option> flag allows the subdirectories to be
 	mount points.  In other words, it will not mount the
 	subdirectories but permit the client to mount only the
 	directories that are required or needed.</para>
 
       <programlisting>/home  -alldirs  10.0.0.2 10.0.0.3 10.0.0.4</programlisting>
 
       <para>The following line exports <filename>/a</filename> so that
 	two clients from different domains may access the file system.
 	The <option>-maproot=root</option> flag allows the
 	<username>root</username> user on the remote system to write
 	data on the exported file system as <username>root</username>.
 	If the <literal>-maproot=root</literal> flag is not specified,
 	then even if a user has <username>root</username> access on
 	the remote system, he will not be able to modify files on
 	the exported file system.</para>
 
       <programlisting>/a  -maproot=root  host.example.com box.example.org</programlisting>
 
       <para>In order for a client to access an exported file system,
 	the client must have permission to do so.  Make sure the
 	client is listed in your <filename>/etc/exports</filename>
 	file.</para>
 
       <para>In <filename>/etc/exports</filename>, each line represents
 	the export information for one file system to one host.  A
 	remote host can only be specified once per file system, and may
 	only have one default entry.  For example, assume that
 	<filename>/usr</filename> is a single file system.  The
 	following <filename>/etc/exports</filename> would be
 	invalid:</para>
 
       <programlisting># Invalid when /usr is one file system
 /usr/src   client
 /usr/ports client</programlisting>
 
       <para>One file system, <filename>/usr</filename>, has two lines
 	specifying exports to the same host, <hostid>client</hostid>.
         The correct format for this situation is:</para>
 
       <programlisting>/usr/src /usr/ports  client</programlisting>
 
       <para>The properties of one file system exported to a given host
 	must all occur on one line.  Lines without a client specified
 	are treated as a single host.  This limits how you can export
 	file systems, but for most people this is not an issue.</para>
 
       <para>The following is an example of a valid export list, where
 	<filename>/usr</filename> and <filename>/exports</filename>
 	are local file systems:</para>
 
       <programlisting># Export src and ports to client01 and client02, but only
 # client01 has root privileges on it
 /usr/src /usr/ports -maproot=root    client01
 /usr/src /usr/ports               client02
 # The client machines have root and can mount anywhere
 # on /exports. Anyone in the world can mount /exports/obj read-only
 /exports -alldirs -maproot=root      client01 client02
 /exports/obj -ro</programlisting>
 
       <para>The <application>mountd</application> daemon must be forced to
 	recheck the <filename>/etc/exports</filename> file whenever it has
 	been modified, so the changes can take effect.  This can be
 	accomplished either by sending a HUP signal to the running daemon:</para>
 
       <screen>&prompt.root; <userinput>kill -HUP `cat /var/run/mountd.pid`</userinput></screen>
 
       <para>or by invoking the <command>mountd</command> &man.rc.8; script
         with the appropriate parameter:</para>
 
       <screen>&prompt.root; <userinput>/etc/rc.d/mountd reload</userinput></screen>
 
       <para>Please refer to <xref linkend="configtuning-rcd"> for more
 	information about using rc scripts.</para>
 
       <para>Alternatively, a reboot will make FreeBSD set everything
         up properly.  A reboot is not necessary though.
         Executing the following commands as <username>root</username>
         should start everything up.</para>
 
       <para>On the <acronym>NFS</acronym> server:</para>
 
       <screen>&prompt.root; <userinput>rpcbind</userinput>
 &prompt.root; <userinput>nfsd -u -t -n 4</userinput>
 &prompt.root; <userinput>mountd -r</userinput></screen>
 
       <para>On the <acronym>NFS</acronym> client:</para>
 
       <screen>&prompt.root; <userinput>nfsiod -n 4</userinput></screen>
 
       <para>Now everything should be ready to actually mount a remote file
 	system.  In these examples the
 	server's name will be <hostid>server</hostid> and the client's
 	name will be <hostid>client</hostid>.  If you only want to
 	temporarily mount a remote file system or would rather test the
 	configuration, just execute a command like this as <username>root</username> on the
         client:</para>
       <indexterm>
         <primary>NFS</primary>
         <secondary>mounting</secondary>
       </indexterm>
       <screen>&prompt.root; <userinput>mount server:/home /mnt</userinput></screen>
 
       <para>This will mount the <filename>/home</filename> directory
 	on the server at <filename>/mnt</filename> on the client.  If
 	everything is set up correctly you should be able to enter
 	<filename>/mnt</filename> on the client and see all the files
         that are on the server.</para>
 
       <para>If you want to automatically mount a remote file system
 	each time the computer boots, add the file system to the
 	<filename>/etc/fstab</filename> file.  Here is an example:</para>
 
       <programlisting>server:/home	/mnt	nfs	rw	0	0</programlisting>
 
       <para>The &man.fstab.5; manual page lists all the available
         options.</para>
     </sect2>
 
     <sect2>
       <title>Practical Uses</title>
 
       <para><acronym>NFS</acronym> has many practical uses.  Some of
         the more common ones are listed below:</para>
 
       <indexterm>
         <primary>NFS</primary>
         <secondary>uses</secondary>
       </indexterm>
       <itemizedlist>
         <listitem>
 	  <para>Set several machines to share a CDROM or other media
 	    among them.  This is cheaper and often a more convenient
 	    method to install software on multiple machines.</para>
 	</listitem>
 
 	<listitem>
 	  <para>On large networks, it might be more convenient to
 	    configure a central <acronym>NFS</acronym> server in which
 	    to store all the user home directories.  These home
 	    directories can then be exported to the network so that
 	    users would always have the same home directory,
 	    regardless of which workstation they log in to.</para>
 	</listitem>
 
 	<listitem>
 	  <para>Several machines could have a common
             <filename>/usr/ports/distfiles</filename> directory.  That
             way, when you need to install a port on several machines,
             you can quickly access the source without downloading it
             on each machine.</para>
 	</listitem>
       </itemizedlist>
     </sect2>
 
     <sect2 id="network-amd">
       <sect2info>
 	<authorgroup>
 	  <author>
 	    <firstname>Wylie</firstname>
 	    <surname>Stilwell</surname>
 	    <contrib>Contributed by </contrib>
 	  </author>
 	</authorgroup>
 	<authorgroup>
 	  <author>
 	    <firstname>Chern</firstname>
 	    <surname>Lee</surname>
 	    <contrib>Rewritten by </contrib>
 	  </author>
 	</authorgroup>
       </sect2info>
       <title>Automatic Mounts with <application>amd</application></title>
 
       <indexterm><primary>amd</primary></indexterm>
       <indexterm><primary>automatic mounter daemon</primary></indexterm>
 
       <para>&man.amd.8; (the automatic mounter daemon)
 	automatically mounts a
 	remote file system whenever a file or directory within that
 	file system is accessed.  Filesystems that are inactive for a
 	period of time will also be automatically unmounted by
 	<application>amd</application>.  Using
 	<application>amd</application> provides a simple alternative
 	to permanent mounts, as permanent mounts are usually listed in
         <filename>/etc/fstab</filename>.</para>
 
       <para><application>amd</application> operates by attaching
 	itself as an NFS server to the <filename>/host</filename> and
 	<filename>/net</filename> directories.  When a file is accessed
 	within one of these directories, <application>amd</application>
 	looks up the corresponding remote mount and automatically mounts
 	it.  <filename>/net</filename> is used to mount an exported
 	file system from an IP address, while <filename>/host</filename>
 	is used to mount an export from a remote hostname.</para>
 
       <para>An access to a file within
 	<filename>/host/foobar/usr</filename> would tell
 	<application>amd</application> to attempt to mount the
 	<filename>/usr</filename> export on the host
 	<hostid>foobar</hostid>.</para>
 
       <example>
 	<title>Mounting an Export with <application>amd</application></title>
 
 	<para>You can view the available mounts of a remote host with
 	  the <command>showmount</command> command.  For example, to
 	  view the mounts of a host named <hostid>foobar</hostid>, you
 	  can use:</para>
 
 	<screen>&prompt.user; <userinput>showmount -e foobar</userinput>
 Exports list on foobar:
 /usr                               10.10.10.0
 /a                                 10.10.10.0
 &prompt.user; <userinput>cd /host/foobar/usr</userinput></screen>
       </example>
 
       <para>As seen in the example, the <command>showmount</command> shows
 	<filename>/usr</filename> as an export.  When changing directories to
 	<filename>/host/foobar/usr</filename>, <application>amd</application>
 	attempts to resolve the hostname <hostid>foobar</hostid> and
 	automatically mount the desired export.</para>
 
       <para><application>amd</application> can be started by the
 	startup scripts by placing the following lines in
 	<filename>/etc/rc.conf</filename>:</para>
 
       <programlisting>amd_enable="YES"</programlisting>
 
       <para>Additionally, custom flags can be passed to
       <application>amd</application> from the
       <varname>amd_flags</varname> option.  By default,
       <varname>amd_flags</varname> is set to:</para>
 
       <programlisting>amd_flags="-a /.amd_mnt -l syslog /host /etc/amd.map /net /etc/amd.map"</programlisting>
 
       <para>The <filename>/etc/amd.map</filename> file defines the
 	default options that exports are mounted with.  The
 	<filename>/etc/amd.conf</filename> file defines some of the more
 	advanced features of <application>amd</application>.</para>
 
       <para>Consult the &man.amd.8; and &man.amd.conf.5; manual pages for more
 	information.</para>
     </sect2>
 
     <sect2 id="network-nfs-integration">
       <sect2info>
         <authorgroup>
           <author>
             <firstname>John</firstname>
             <surname>Lind</surname>
             <contrib>Contributed by </contrib>
           </author>
         </authorgroup>
       </sect2info>
       <title>Problems Integrating with Other Systems</title>
 
       <para>Certain Ethernet adapters for ISA PC systems have limitations
 	which can lead to serious network problems, particularly with NFS.
 	This difficulty is not specific to FreeBSD, but FreeBSD systems
 	are affected by it.</para>
 
       <para>The problem nearly always occurs when (FreeBSD) PC systems are
 	networked with high-performance workstations, such as those made
 	by Silicon Graphics, Inc., and Sun Microsystems, Inc.  The NFS
 	mount will work fine, and some operations may succeed, but
 	suddenly the server will seem to become unresponsive to the
 	client, even though requests to and from other systems continue to
 	be processed.  This happens to the client system, whether the
 	client is the FreeBSD system or the workstation.  On many systems,
 	there is no way to shut down the client gracefully once this
 	problem has manifested itself.  The only solution is often to
 	reset the client, because the NFS situation cannot be
 	resolved.</para>
 
       <para>Though the <quote>correct</quote> solution is to get a
 	higher performance and capacity Ethernet adapter for the
 	FreeBSD system, there is a simple workaround that will allow
 	satisfactory operation.  If the FreeBSD system is the
 	<emphasis>server</emphasis>, include the option
 	<option>-w=1024</option> on the mount from the client.  If the
 	FreeBSD system is the <emphasis>client</emphasis>, then mount
 	the NFS file system with the option <option>-r=1024</option>.
 	These options may be specified using the fourth field of the
 	<filename>fstab</filename> entry on the client for automatic
 	mounts, or by using the <option>-o</option> parameter of the
 	&man.mount.8; command for manual mounts.</para>
 
       <para>It should be noted that there is a different problem,
 	sometimes mistaken for this one, when the NFS servers and
 	clients are on different networks.  If that is the case, make
 	<emphasis>certain</emphasis> that your routers are routing the
 	necessary <acronym>UDP</acronym> information, or you will not get anywhere, no
 	matter what else you are doing.</para>
 
       <para>In the following examples, <hostid>fastws</hostid> is the host
 	(interface) name of a high-performance workstation, and
 	<hostid>freebox</hostid> is the host (interface) name of a FreeBSD
 	system with a lower-performance Ethernet adapter.  Also,
 	<filename>/sharedfs</filename> will be the exported NFS
 	file system (see &man.exports.5;), and
 	<filename>/project</filename> will be the mount point on the
 	client for the exported file system.  In all cases, note that
 	additional options, such as <option>hard</option> or
 	<option>soft</option> and <option>bg</option> may be desirable in
 	your application.</para>
 
       <para>Examples for the FreeBSD system (<hostid>freebox</hostid>)
 	as the client in <filename>/etc/fstab</filename> on
 	<hostid>freebox</hostid>:</para>
 
       <programlisting>fastws:/sharedfs /project nfs rw,-r=1024 0 0</programlisting>
 
       <para>As a manual mount command on <hostid>freebox</hostid>:</para>
 
       <screen>&prompt.root; <userinput>mount -t nfs -o -r=1024 fastws:/sharedfs /project</userinput></screen>
 
       <para>Examples for the FreeBSD system as the server in
 	<filename>/etc/fstab</filename> on
 	<hostid>fastws</hostid>:</para>
 
       <programlisting>freebox:/sharedfs /project nfs rw,-w=1024 0 0</programlisting>
 
       <para>As a manual mount command on <hostid>fastws</hostid>:</para>
 
       <screen>&prompt.root; <userinput>mount -t nfs -o -w=1024 freebox:/sharedfs /project</userinput></screen>
 
       <para>Nearly any 16-bit Ethernet adapter will allow operation
 	without the above restrictions on the read or write size.</para>
 
       <para>For anyone who cares, here is what happens when the
 	failure occurs, which also explains why it is unrecoverable.
 	NFS typically works with a <quote>block</quote> size of
 	8&nbsp;K (though it may do fragments of smaller sizes).  Since
 	the maximum Ethernet packet is around 1500&nbsp;bytes, the NFS
 	<quote>block</quote> gets split into multiple Ethernet
 	packets, even though it is still a single unit to the
 	upper-level code, and must be received, assembled, and
 	<emphasis>acknowledged</emphasis> as a unit.  The
 	high-performance workstations can pump out the packets which
 	comprise the NFS unit one right after the other, just as close
 	together as the standard allows.  On the smaller, lower
 	capacity cards, the later packets overrun the earlier packets
 	of the same unit before they can be transferred to the host
 	and the unit as a whole cannot be reconstructed or
 	acknowledged.  As a result, the workstation will time out and
 	try again, but it will try again with the entire 8&nbsp;K
 	unit, and the process will be repeated, ad infinitum.</para>
 
       <para>By keeping the unit size below the Ethernet packet size
 	limitation, we ensure that any complete Ethernet packet
 	received can be acknowledged individually, avoiding the
 	deadlock situation.</para>
 
       <para>Overruns may still occur when a high-performance
 	workstations is slamming data out to a PC system, but with the
 	better cards, such overruns are not guaranteed on NFS
 	<quote>units</quote>.  When an overrun occurs, the units
 	affected will be retransmitted, and there will be a fair
 	chance that they will be received, assembled, and
 	acknowledged.</para>
     </sect2>
   </sect1>
 
   <sect1 id="network-nis">
     <sect1info>
       <authorgroup>
         <author>
           <firstname>Bill</firstname>
       	  <surname>Swingle</surname>
 	  <contrib>Written by </contrib>
          </author>
       </authorgroup>
       <authorgroup>
 	<author>
 	  <firstname>Eric</firstname>
 	  <surname>Ogren</surname>
 	  <contrib>Enhanced by </contrib>
 	</author>
 	<author>
 	  <firstname>Udo</firstname>
 	  <surname>Erdelhoff</surname>
 	</author>
       </authorgroup>
     </sect1info>
     <title>Network Information System (NIS/YP)</title>
 
     <sect2>
       <title>What Is It?</title>
       <indexterm><primary>NIS</primary></indexterm>
       <indexterm><primary>Solaris</primary></indexterm>
       <indexterm><primary>HP-UX</primary></indexterm>
       <indexterm><primary>AIX</primary></indexterm>
       <indexterm><primary>Linux</primary></indexterm>
       <indexterm><primary>NetBSD</primary></indexterm>
       <indexterm><primary>OpenBSD</primary></indexterm>
 
       <para><acronym role="Network Information System">NIS</acronym>,
         which stands for Network Information Services, was developed
         by Sun Microsystems to centralize administration of &unix;
         (originally &sunos;) systems.  It has now essentially become
         an industry standard; all major &unix; like systems
         (&solaris;, HP-UX, &aix;, Linux, NetBSD, OpenBSD, FreeBSD,
         etc) support <acronym role="Network Information
         System">NIS</acronym>.</para>
 
       <indexterm><primary>yellow pages</primary><see>NIS</see></indexterm>
 
       <para><acronym role="Network Information System">NIS</acronym>
 	was formerly known as Yellow Pages, but because of trademark
 	issues, Sun changed the name.  The old term (and yp) is still
 	often seen and used.</para>
 
       <indexterm>
         <primary>NIS</primary>
         <secondary>domains</secondary>
       </indexterm>
 
       <para>It is a RPC-based client/server system that allows a group
 	of machines within an NIS domain to share a common set of
 	configuration files.  This permits a system administrator to
 	set up NIS client systems with only minimal configuration data
 	and add, remove or modify configuration data from a single
 	location.</para>
 
       <indexterm><primary>Windows NT</primary></indexterm>
 
       <para>It is similar to the &windowsnt; domain system; although
         the internal implementation of the two are not at all similar,
         the basic functionality can be compared.</para>
     </sect2>
 
     <sect2>
       <title>Terms/Processes You Should Know</title>
 
       <para>There are several terms and several important user
         processes that you will come across when attempting to
         implement NIS on FreeBSD, whether you are trying to create an
         NIS server or act as an NIS client:</para>
 
       <indexterm>
 	<primary><application>rpcbind</application></primary>
       </indexterm>
       <indexterm>
 	<primary><application>portmap</application></primary>
       </indexterm>
 
       <informaltable frame="none" pgwide="1">
 	<tgroup cols="2">
 	<colspec colwidth="1*">
 	<colspec colwidth="3*">
 
 	  <thead>
 	    <row>
 	      <entry>Term</entry>
 	      <entry>Description</entry>
 	    </row>
 	  </thead>
 	  <tbody>
 	    <row>
 	      <entry>NIS domainname</entry>
 
 	      <entry>An NIS master server and all of its clients
 		(including its slave servers) have a NIS domainname.
 		Similar to an &windowsnt; domain name, the NIS
 		domainname does not have anything to do with
 		<acronym>DNS</acronym>.</entry>
 	    </row>
 	    <row>
 	      <entry><application>rpcbind</application></entry>
 
 	      <entry>Must be running in order to enable
 		<acronym>RPC</acronym> (Remote Procedure Call, a
 		network protocol used by NIS).  If
 		<application>rpcbind</application> is not running, it
 		will be impossible to run an NIS server, or to act as
 		an NIS client.</entry>
 	    </row>
 	    <row>
 	      <entry><application>ypbind</application></entry>
 
 	      <entry><quote>Binds</quote> an NIS client to its NIS
 		server.  It will take the NIS domainname from the
 		system, and using <acronym>RPC</acronym>, connect to
 		the server.  <application>ypbind</application> is the
 		core of client-server communication in an NIS
 		environment; if <application>ypbind</application> dies
 		on a client machine, it will not be able to access the
 		NIS server.</entry>
 	    </row>
 	    <row>
 	      <entry><application>ypserv</application></entry>
 	      <entry>Should only be running on NIS servers; this is
 		the NIS server process itself.  If &man.ypserv.8;
 		dies, then the server will no longer be able to
 		respond to NIS requests (hopefully, there is a slave
 		server to take over for it).  There are some
 		implementations of NIS (but not the FreeBSD one), that
 		do not try to reconnect to another server if the
 		server it used before dies.  Often, the only thing
 		that helps in this case is to restart the server
 		process (or even the whole server) or the
 		<application>ypbind</application> process on the
 		client.
 	      </entry>
 	    </row>
 	    <row>
 	      <entry><application>rpc.yppasswdd</application></entry>
 	      <entry>Another process that should only be running on
 		NIS master servers; this is a daemon that will allow NIS
 		clients to change their NIS passwords.  If this daemon
 		is not running, users will have to login to the NIS
 		master server and change their passwords there.</entry>
 	    </row>
 	  </tbody>
 	</tgroup>
       </informaltable>
       <!-- XXX Missing: rpc.ypxfrd (not important, though) May only run
       on the master -->
 
     </sect2>
 
     <sect2>
       <title>How Does It Work?</title>
 
       <para>There are three types of hosts in an NIS environment:
 	master servers, slave servers, and clients.  Servers act as a
 	central repository for host configuration information.  Master
 	servers hold the authoritative copy of this information, while
 	slave servers mirror this information for redundancy.  Clients
 	rely on the servers to provide this information to
 	them.</para>
 
       <para>Information in many files can be shared in this manner.
 	The <filename>master.passwd</filename>,
 	<filename>group</filename>, and <filename>hosts</filename>
 	files are commonly shared via NIS.  Whenever a process on a
 	client needs information that would normally be found in these
 	files locally, it makes a query to the NIS server that it is
 	bound to instead.</para>
 
       <sect3>
         <title>Machine Types</title>
 
         <itemizedlist>
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>master server</secondary>
 	  </indexterm>
           <listitem>
             <para>A <emphasis>NIS master server</emphasis>.  This
               server, analogous to a &windowsnt; primary domain
               controller, maintains the files used by all of the NIS
               clients.  The <filename>passwd</filename>,
               <filename>group</filename>, and other various files used
               by the NIS clients live on the master server.</para>
 
             <note><para>It is possible for one machine to be an NIS
               master server for more than one NIS domain.  However,
               this will not be covered in this introduction, which
               assumes a relatively small-scale NIS
               environment.</para></note>
           </listitem>
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>slave server</secondary>
 	  </indexterm>
           <listitem>
             <para><emphasis>NIS slave servers</emphasis>.  Similar to
               the &windowsnt; backup domain controllers, NIS slave
               servers maintain copies of the NIS master's data files.
               NIS slave servers provide the redundancy, which is
               needed in important environments.  They also help to
               balance the load of the master server: NIS Clients
               always attach to the NIS server whose response they get
               first, and this includes slave-server-replies.</para>
           </listitem>
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>client</secondary>
 	  </indexterm>
           <listitem>
             <para><emphasis>NIS clients</emphasis>.  NIS clients, like
               most &windowsnt; workstations, authenticate against the
               NIS server (or the &windowsnt; domain controller in the
               &windowsnt; workstations case) to log on.</para>
           </listitem>
         </itemizedlist>
       </sect3>
     </sect2>
 
     <sect2>
       <title>Using NIS/YP</title>
 
       <para>This section will deal with setting up a sample NIS
         environment.</para>
 
       <note><para>This section assumes that you are running
         FreeBSD&nbsp;3.3 or later.  The instructions given here will
         <emphasis>probably</emphasis> work for any version of FreeBSD
         greater than 3.0, but there are no guarantees that this is
         true.</para></note>
 
 
       <sect3>
         <title>Planning</title>
 
         <para>Let us assume that you are the administrator of a small
           university lab.  This lab, which consists of 15 FreeBSD
           machines, currently has no centralized point of
           administration; each machine has its own
           <filename>/etc/passwd</filename> and
           <filename>/etc/master.passwd</filename>.  These files are
           kept in sync with each other only through manual
           intervention; currently, when you add a user to the lab, you
           must run <command>adduser</command> on all 15 machines.
           Clearly, this has to change, so you have decided to convert
           the lab to use NIS, using two of the machines as
           servers.</para>
 
         <para>Therefore, the configuration of the lab now looks something
           like:</para>
 
         <informaltable frame="none" pgwide="1">
           <tgroup cols="3">
             <thead>
               <row>
                 <entry>Machine name</entry>
                 <entry>IP address</entry>
                 <entry>Machine role</entry>
               </row>
             </thead>
             <tbody>
               <row>
                 <entry><hostid>ellington</hostid></entry>
                 <entry><hostid role="ipaddr">10.0.0.2</hostid></entry>
                 <entry>NIS master</entry>
               </row>
               <row>
                 <entry><hostid>coltrane</hostid></entry>
                 <entry><hostid role="ipaddr">10.0.0.3</hostid></entry>
                 <entry>NIS slave</entry>
               </row>
               <row>
                 <entry><hostid>basie</hostid></entry>
                 <entry><hostid role="ipaddr">10.0.0.4</hostid></entry>
                 <entry>Faculty workstation</entry>
               </row>
               <row>
                 <entry><hostid>bird</hostid></entry>
                 <entry><hostid role="ipaddr">10.0.0.5</hostid></entry>
                 <entry>Client machine</entry>
               </row>
               <row>
                 <entry><hostid>cli[1-11]</hostid></entry>
                 <entry><hostid role="ipaddr">10.0.0.[6-17]</hostid></entry>
                 <entry>Other client machines</entry>
               </row>
             </tbody>
           </tgroup>
         </informaltable>
 
         <para>If you are setting up a NIS scheme for the first time, it
 	  is a good idea to think through how you want to go about it.  No
 	  matter what the size of your network, there are a few decisions
 	  that need to be made.</para>
 
         <sect4>
           <title>Choosing a NIS Domain Name</title>
 
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>domainname</secondary>
 	  </indexterm>
           <para>This might not be the <quote>domainname</quote> that
 	    you are used to.  It is more accurately called the
 	    <quote>NIS domainname</quote>.  When a client broadcasts
 	    its requests for info, it includes the name of the NIS
 	    domain that it is part of.  This is how multiple servers
 	    on one network can tell which server should answer which
 	    request.  Think of the NIS domainname as the name for a
 	    group of hosts that are related in some way.</para>
 
 	  <para>Some organizations choose to use their Internet
 	    domainname for their NIS domainname.  This is not
 	    recommended as it can cause confusion when trying to debug
 	    network problems.  The NIS domainname should be unique
 	    within your network and it is helpful if it describes the
 	    group of machines it represents.  For example, the Art
 	    department at Acme Inc. might be in the
 	    <quote>acme-art</quote> NIS domain.  For this example,
 	    assume you have chosen the name
 	    <literal>test-domain</literal>.</para>
 
 	  <indexterm><primary>SunOS</primary></indexterm>
           <para>However, some operating systems (notably &sunos;) use
           their NIS domain name as their Internet domain name.  If one
           or more machines on your network have this restriction, you
           <emphasis>must</emphasis> use the Internet domain name as
           your NIS domain name.</para>
         </sect4>
 
         <sect4>
           <title>Physical Server Requirements</title>
 
 	  <para>There are several things to keep in mind when choosing
 	    a machine to use as a NIS server.  One of the unfortunate
 	    things about NIS is the level of dependency the clients
 	    have on the server.  If a client cannot contact the server
 	    for its NIS domain, very often the machine becomes
 	    unusable.  The lack of user and group information causes
 	    most systems to temporarily freeze up.  With this in mind
 	    you should make sure to choose a machine that will not be
 	    prone to being rebooted regularly, or one that might be
 	    used for development.  The NIS server should ideally be a
 	    stand alone machine whose sole purpose in life is to be an
 	    NIS server.  If you have a network that is not very
 	    heavily used, it is acceptable to put the NIS server on a
 	    machine running other services, just keep in mind that if
 	    the NIS server becomes unavailable, it will affect
 	    <emphasis>all</emphasis> of your NIS clients
 	    adversely.</para>
         </sect4>
       </sect3>
 
       <sect3>
         <title>NIS Servers</title>
 
 	<para> The canonical copies of all NIS information are stored
 	  on a single machine called the NIS master server.  The
 	  databases used to store the information are called NIS maps.
 	  In FreeBSD, these maps are stored in
 	  <filename>/var/yp/[domainname]</filename> where
 	  <filename>[domainname]</filename> is the name of the NIS
 	  domain being served.  A single NIS server can support
 	  several domains at once, therefore it is possible to have
 	  several such directories, one for each supported domain.
 	  Each domain will have its own independent set of
 	  maps.</para>
 
 	<para>NIS master and slave servers handle all NIS requests
 	  with the <command>ypserv</command> daemon.
 	  <command>ypserv</command> is responsible for receiving
 	  incoming requests from NIS clients, translating the
 	  requested domain and map name to a path to the corresponding
 	  database file and transmitting data from the database back
 	  to the client.</para>
 
         <sect4>
 	  <title>Setting Up a NIS Master Server</title>
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>server configuration</secondary>
 	  </indexterm>
 	  <para>Setting up a master NIS server can be relatively
 	    straight forward, depending on your needs.  FreeBSD comes
 	    with support for NIS out-of-the-box.  All you need is to
 	    add the following lines to
 	    <filename>/etc/rc.conf</filename>, and FreeBSD will do the
 	    rest for you.</para>
 
           <procedure>
             <step>
               <para><programlisting>nisdomainname="test-domain"</programlisting>
                 This line will set the NIS domainname to
                 <literal>test-domain</literal>
                 upon network setup (e.g. after reboot).</para>
             </step>
             <step>
               <para><programlisting>nis_server_enable="YES"</programlisting>
                 This will tell FreeBSD to start up the NIS server processes
                 when the networking is next brought up.</para>
             </step>
             <step>
               <para><programlisting>nis_yppasswdd_enable="YES"</programlisting>
                 This will enable the <command>rpc.yppasswdd</command>
                 daemon which, as mentioned above, will allow users to
                 change their NIS password from a client machine.</para>
             </step>
           </procedure>
 
           <note>
             <para>Depending on your NIS setup, you may need to add
               further entries.  See the <link
               linkend="network-nis-server-is-client">section about NIS
               servers that are also NIS clients</link>, below, for
               details.</para>
           </note>
 
           <para>Now, all you have to do is to run the command
             <command>/etc/netstart</command> as superuser.  It will
             set up everything for you, using the values you defined in
             <filename>/etc/rc.conf</filename>.</para>
         </sect4>
 
         <sect4>
           <title>Initializing the NIS Maps</title>
           <indexterm>
             <primary>NIS</primary>
             <secondary>maps</secondary>
           </indexterm>
           <para>The <emphasis>NIS maps</emphasis> are database files,
             that are kept in the <filename>/var/yp</filename>
             directory.  They are generated from configuration files in
             the <filename>/etc</filename> directory of the NIS master,
             with one exception: the
             <filename>/etc/master.passwd</filename> file.  This is for
             a good reason, you do not want to propagate passwords to
             your <username>root</username> and other administrative
             accounts to all the servers in the NIS domain.  Therefore,
             before we initialize the NIS maps, you should:</para>
 
           <screen>&prompt.root; <userinput>cp /etc/master.passwd /var/yp/master.passwd</userinput>
 &prompt.root; <userinput>cd /var/yp</userinput>
 &prompt.root; <userinput>vi master.passwd</userinput></screen>
 
           <para>You should remove all entries regarding system
             accounts (<username>bin</username>,
             <username>tty</username>, <username>kmem</username>,
             <username>games</username>, etc), as well as any accounts
             that you do not want to be propagated to the NIS clients
             (for example <username>root</username> and any other UID 0
             (superuser) accounts).</para>
 
           <note><para>Make sure the
             <filename>/var/yp/master.passwd</filename> is neither group
             nor world readable (mode 600)!  Use the
             <command>chmod</command> command, if appropriate.</para></note>
 
 	  <indexterm><primary>Tru64 UNIX</primary></indexterm>
 
           <para>When you have finished, it is time to initialize the
             NIS maps!  FreeBSD includes a script named
             <command>ypinit</command> to do this for you (see its
             manual page for more information).  Note that this script
             is available on most &unix; Operating Systems, but not on
             all.  On Digital UNIX/Compaq Tru64 UNIX it is called
             <command>ypsetup</command>.  Because we are generating
             maps for an NIS master, we are going to pass the
             <option>-m</option> option to <command>ypinit</command>.
             To generate the NIS maps, assuming you already performed
             the steps above, run:</para>
 
           <screen>ellington&prompt.root; <userinput>ypinit -m test-domain</userinput>
 Server Type: MASTER Domain: test-domain
 Creating an YP server will require that you answer a few questions.
 Questions will all be asked at the beginning of the procedure.
 Do you want this procedure to quit on non-fatal errors? [y/n: n] <userinput>n</userinput>
 Ok, please remember to go back and redo manually whatever fails.
 If you don't, something might not work.
 At this point, we have to construct a list of this domains YP servers.
 rod.darktech.org is already known as master server.
 Please continue to add any slave servers, one per line. When you are
 done with the list, type a &lt;control D&gt;.
 master server   :  ellington
 next host to add:  <userinput>coltrane</userinput>
 next host to add:  <userinput>^D</userinput>
 The current list of NIS servers looks like this:
 ellington
 coltrane
 Is this correct?  [y/n: y] <userinput>y</userinput>
 
 [..output from map generation..]
 
 NIS Map update completed.
 ellington has been setup as an YP master server without any errors.</screen>
 
           <para><command>ypinit</command> should have created
             <filename>/var/yp/Makefile</filename> from
             <filename>/var/yp/Makefile.dist</filename>.
             When created, this file assumes that you are operating
             in a single server NIS environment with only FreeBSD
             machines.  Since <literal>test-domain</literal> has
             a slave server as well, you must edit
             <filename>/var/yp/Makefile</filename>:</para>
 
           <screen>ellington&prompt.root; <userinput>vi /var/yp/Makefile</userinput></screen>
 
 	  <para>You should comment out the line that says</para>
 
 	  <programlisting>NOPUSH = "True"</programlisting>
 
 	  <para>(if it is not commented out already).</para>
         </sect4>
 
         <sect4>
 	  <title>Setting up a NIS Slave Server</title>
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>slave server</secondary>
 	  </indexterm>
 	  <para>Setting up an NIS slave server is even more simple than
 	    setting up the master.  Log on to the slave server and edit the
             file <filename>/etc/rc.conf</filename> as you did before.
             The only difference is that we now must use the
             <option>-s</option> option when running <command>ypinit</command>.
             The <option>-s</option> option requires the name of the NIS
             master be passed to it as well, so our command line looks
             like:</para>
 
   <screen>coltrane&prompt.root; <userinput>ypinit -s ellington test-domain</userinput>
 
 Server Type: SLAVE Domain: test-domain Master: ellington
 
 Creating an YP server will require that you answer a few questions.
 Questions will all be asked at the beginning of the procedure.
 
 Do you want this procedure to quit on non-fatal errors? [y/n: n]  <userinput>n</userinput>
 
 Ok, please remember to go back and redo manually whatever fails.
 If you don't, something might not work.
 There will be no further questions. The remainder of the procedure
 should take a few minutes, to copy the databases from ellington.
 Transferring netgroup...
 ypxfr: Exiting: Map successfully transferred
 Transferring netgroup.byuser...
 ypxfr: Exiting: Map successfully transferred
 Transferring netgroup.byhost...
 ypxfr: Exiting: Map successfully transferred
 Transferring master.passwd.byuid...
 ypxfr: Exiting: Map successfully transferred
 Transferring passwd.byuid...
 ypxfr: Exiting: Map successfully transferred
 Transferring passwd.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring group.bygid...
 ypxfr: Exiting: Map successfully transferred
 Transferring group.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring services.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring rpc.bynumber...
 ypxfr: Exiting: Map successfully transferred
 Transferring rpc.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring protocols.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring master.passwd.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring networks.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring networks.byaddr...
 ypxfr: Exiting: Map successfully transferred
 Transferring netid.byname...
 ypxfr: Exiting: Map successfully transferred
 Transferring hosts.byaddr...
 ypxfr: Exiting: Map successfully transferred
 Transferring protocols.bynumber...
 ypxfr: Exiting: Map successfully transferred
 Transferring ypservers...
 ypxfr: Exiting: Map successfully transferred
 Transferring hosts.byname...
 ypxfr: Exiting: Map successfully transferred
 
 coltrane has been setup as an YP slave server without any errors.
 Don't forget to update map ypservers on ellington.</screen>
 
 	  <para>You should now have a directory called
 	    <filename>/var/yp/test-domain</filename>.  Copies of the NIS
 	    master server's maps should be in this directory.  You will
 	    need to make sure that these stay updated.  The following
 	    <filename>/etc/crontab</filename> entries on your slave
 	    servers should do the job:</para>
 
 	  <programlisting>20      *       *       *       *       root   /usr/libexec/ypxfr passwd.byname
 21      *       *       *       *       root   /usr/libexec/ypxfr passwd.byuid</programlisting>
 
 	  <para>These two lines force the slave to sync its maps with
 	    the maps on the master server.  Although these entries are
 	    not mandatory, since the master server attempts to ensure
 	    any changes to its NIS maps are communicated to its slaves
 	    and because password information is vital to systems
 	    depending on the server, it is a good idea to force the
 	    updates.  This is more important on busy networks where map
 	    updates might not always complete.</para>
 
           <para>Now, run the command <command>/etc/netstart</command> on the
             slave server as well, which again starts the NIS server.</para>
 	</sect4>
       </sect3>
 
       <sect3>
         <title>NIS Clients</title>
 
 	<para> An NIS client establishes what is called a binding to a
 	  particular NIS server using the
 	  <command>ypbind</command> daemon.
 	  <command>ypbind</command> checks the system's default
 	  domain (as set by the <command>domainname</command> command),
 	  and begins broadcasting RPC requests on the local network.
 	  These requests specify the name of the domain for which
 	  <command>ypbind</command> is attempting to establish a binding.
 	  If a server that has been configured to serve the requested
 	  domain receives one of the broadcasts, it will respond to
 	  <command>ypbind</command>,  which will record the server's
 	  address.  If there are several servers available (a master and
 	  several slaves, for example), <command>ypbind</command> will
 	  use the address of the first one to respond.  From that point
 	  on, the client system will direct all of its NIS requests to
 	  that server.  <command>ypbind</command> will
 	  occasionally <quote>ping</quote> the server to make sure it is
 	  still up and running.  If it fails to receive a reply to one of
 	  its pings within a reasonable amount of time,
 	  <command>ypbind</command> will mark the domain as unbound and
 	  begin broadcasting again in the hopes of locating another
 	  server.</para>
 
 	<sect4>
 	  <title>Setting Up a NIS Client</title>
 	  <indexterm>
 	    <primary>NIS</primary>
 	    <secondary>client configuration</secondary>
 	  </indexterm>
 	  <para>Setting up a FreeBSD machine to be a NIS client is fairly
 	    straightforward.</para>
 
 	  <procedure>
 	    <step>
 	      <para>Edit the file <filename>/etc/rc.conf</filename> and
                 add the following lines in order to set the NIS domainname
                 and start <command>ypbind</command> upon network
                 startup:</para>
 
 	      <programlisting>nisdomainname="test-domain"
 nis_client_enable="YES"</programlisting>
 	    </step>
 
 	    <step>
 	      <para>To import all possible password entries from the NIS
 		server, remove all user accounts from your
 		<filename>/etc/master.passwd</filename> file and use
 		<command>vipw</command> to add the following line to
                 the end of the file:</para>
 
 	      <programlisting>+:::::::::</programlisting>
 
 	      <note>
 		<para>This line will afford anyone with a valid account in
 		  the NIS server's password maps an account.  There are
 		  many ways to configure your NIS client by changing this
 		  line.  See the <link linkend="network-netgroups">netgroups
 		  section</link> below for more information.
                   For more detailed reading see O'Reilly's book on
 		  <literal>Managing NFS and NIS</literal>.</para>
 	      </note>
 
               <note>
                 <para>You should keep at least one local account (i.e.
                   not imported via NIS) in your
                   <filename>/etc/master.passwd</filename> and this
                   account should also be a member of the group
                   <groupname>wheel</groupname>.  If there is something
                   wrong with NIS, this account can be used to log in
                   remotely, become <username>root</username>, and fix things.</para>
               </note>
             </step>
 
 	    <step>
 	      <para>To import all possible group entries from the NIS
 		server, add this line to your
 		<filename>/etc/group</filename> file:</para>
 
 	      <programlisting>+:*::</programlisting>
 	    </step>
 	  </procedure>
 
 	  <para>After completing these steps, you should be able to run
 	    <command>ypcat passwd</command> and see the NIS server's
 	    passwd map.</para>
 	</sect4>
       </sect3>
     </sect2>
 
     <sect2>
       <title>NIS Security</title>
 
       <para>In general, any remote user can issue an RPC to
 	&man.ypserv.8; and retrieve the contents of your NIS maps,
 	provided the remote user knows your domainname.  To prevent
 	such unauthorized transactions, &man.ypserv.8; supports a
 	feature called <quote>securenets</quote> which can be used to
 	restrict access to a given set of hosts.  At startup,
 	&man.ypserv.8; will attempt to load the securenets information
 	from a file called
 	<filename>/var/yp/securenets</filename>.</para>
 
       <note>
 	<para>This path varies depending on the path specified with the
 	  <option>-p</option> option.  This file contains entries that
 	  consist of a network specification and a network mask separated
 	  by white space.  Lines starting with <quote>#</quote> are
 	  considered to be comments.  A sample securenets file might look
 	  like this:</para>
       </note>
 
       <programlisting># allow connections from local host -- mandatory
 127.0.0.1     255.255.255.255
 # allow connections from any host
 # on the 192.168.128.0 network
 192.168.128.0 255.255.255.0
 # allow connections from any host
 # between 10.0.0.0 to 10.0.15.255
 # this includes the machines in the testlab
 10.0.0.0      255.255.240.0</programlisting>
 
       <para>If &man.ypserv.8; receives a request from an address that
 	matches one of these rules, it will process the request
 	normally.  If the address fails to match a rule, the request
 	will be ignored and a warning message will be logged.  If the
 	<filename>/var/yp/securenets</filename> file does not exist,
 	<command>ypserv</command> will allow connections from any
 	host.</para>
 
       <para>The <command>ypserv</command> program also has support for
 	Wietse Venema's <application>TCP Wrapper</application> package.
 	This allows the administrator to use the
 	<application>TCP Wrapper</application> configuration files for
 	access control instead of
 	<filename>/var/yp/securenets</filename>.</para>
 
       <note>
         <para>While both of these access control mechanisms provide some
           security, they, like the privileged port test, are
           vulnerable to <quote>IP spoofing</quote> attacks.  All
           NIS-related traffic should be blocked at your firewall.</para>
 
         <para>Servers using <filename>/var/yp/securenets</filename>
           may fail to serve legitimate NIS clients with archaic TCP/IP
           implementations.  Some of these implementations set all
           host bits to zero when doing broadcasts and/or fail to
           observe the subnet mask when calculating the broadcast
           address.  While some of these problems can be fixed by
           changing the client configuration, other problems may force
           the retirement of the client systems in question or the
           abandonment of <filename>/var/yp/securenets</filename>.</para>
 
         <para>Using <filename>/var/yp/securenets</filename> on a
           server with such an archaic implementation of TCP/IP is a
           really bad idea and will lead to loss of NIS functionality
           for large parts of your network.</para>
 
 	<indexterm><primary>TCP Wrappers</primary></indexterm>
         <para>The use of the <application>TCP Wrapper</application>
           package increases the latency of your NIS server.  The
           additional delay may be long enough to cause timeouts in
           client programs, especially in busy networks or with slow
           NIS servers.  If one or more of your client systems
           suffers from these symptoms, you should convert the client
           systems in question into NIS slave servers and force them
           to bind to themselves.</para>
       </note>
     </sect2>
 
     <sect2>
       <title>Barring Some Users from Logging On</title>
 
       <para>In our lab, there is a machine <hostid>basie</hostid> that
         is supposed to be a faculty only workstation.  We do not want
         to take this machine out of the NIS domain, yet the
         <filename>passwd</filename> file on the master NIS server
         contains accounts for both faculty and students.  What can we
         do?</para>
 
       <para>There is a way to bar specific users from logging on to a
         machine, even if they are present in the NIS database.  To do
         this, all you must do is add
         <literal>-<replaceable>username</replaceable></literal> to the
         end of the <filename>/etc/master.passwd</filename> file on the
         client machine, where <replaceable>username</replaceable> is
         the username of the user you wish to bar from logging in.
         This should preferably be done using <command>vipw</command>,
         since <command>vipw</command> will sanity check your changes
         to <filename>/etc/master.passwd</filename>, as well as
         automatically rebuild the password database when you finish
         editing.  For example, if we wanted to bar user
         <username>bill</username> from logging on to
         <hostid>basie</hostid> we would:</para>
 
         <screen>basie&prompt.root; <userinput>vipw</userinput>
 <userinput>[add -bill to the end, exit]</userinput>
 vipw: rebuilding the database...
 vipw: done
 
 basie&prompt.root; <userinput>cat /etc/master.passwd</userinput>
 
 root:[password]:0:0::0:0:The super-user:/root:/bin/csh
 toor:[password]:0:0::0:0:The other super-user:/root:/bin/sh
 daemon:*:1:1::0:0:Owner of many system processes:/root:/sbin/nologin
 operator:*:2:5::0:0:System &:/:/sbin/nologin
 bin:*:3:7::0:0:Binaries Commands and Source,,,:/:/sbin/nologin
 tty:*:4:65533::0:0:Tty Sandbox:/:/sbin/nologin
 kmem:*:5:65533::0:0:KMem Sandbox:/:/sbin/nologin
 games:*:7:13::0:0:Games pseudo-user:/usr/games:/sbin/nologin
 news:*:8:8::0:0:News Subsystem:/:/sbin/nologin
 man:*:9:9::0:0:Mister Man Pages:/usr/share/man:/sbin/nologin
 bind:*:53:53::0:0:Bind Sandbox:/:/sbin/nologin
 uucp:*:66:66::0:0:UUCP pseudo-user:/var/spool/uucppublic:/usr/libexec/uucp/uucico
 xten:*:67:67::0:0:X-10 daemon:/usr/local/xten:/sbin/nologin
 pop:*:68:6::0:0:Post Office Owner:/nonexistent:/sbin/nologin
 nobody:*:65534:65534::0:0:Unprivileged user:/nonexistent:/sbin/nologin
 +:::::::::
 -bill
 
 basie&prompt.root;</screen>
     </sect2>
 
     <sect2 id="network-netgroups">
       <sect2info>
         <authorgroup>
           <author>
             <firstname>Udo</firstname>
             <surname>Erdelhoff</surname>
             <contrib>Contributed by </contrib>
           </author>
         </authorgroup>
       </sect2info>
 
       <title>Using Netgroups</title>
       <indexterm><primary>netgroups</primary></indexterm>
 
       <para>The method shown in the previous section works reasonably
         well if you need special rules for a very small number of
         users and/or machines.  On larger networks, you
         <emphasis>will</emphasis> forget to bar some users from logging
         onto sensitive machines, or you may even have to modify each
         machine separately, thus losing the main benefit of NIS:
         <emphasis>centralized</emphasis> administration.</para>
 
       <para>The NIS developers' solution for this problem is called
         <emphasis>netgroups</emphasis>.  Their purpose and semantics
         can be compared to the normal groups used by &unix; file
         systems.  The main differences are the lack of a numeric ID
         and the ability to define a netgroup by including both user
         accounts and other netgroups.</para>
 
       <para>Netgroups were developed to handle large, complex networks
         with hundreds of users and machines.  On one hand, this is
         a Good Thing if you are forced to deal with such a situation.
         On the other hand, this complexity makes it almost impossible to
         explain netgroups with really simple examples.  The example
         used in the remainder of this section demonstrates this
         problem.</para>
 
       <para>Let us assume that your successful introduction of NIS in
         your laboratory caught your superiors' interest.  Your next
         job is to extend your NIS domain to cover some of the other
         machines on campus.  The two tables contain the names of the
         new users and new machines as well as brief descriptions of
         them.</para>
 
       <informaltable frame="none" pgwide="1">
         <tgroup cols="2">
           <thead>
             <row>
               <entry>User Name(s)</entry>
               <entry>Description</entry>
             </row>
           </thead>
 
           <tbody>
             <row>
               <entry><username>alpha</username>, <username>beta</username></entry>
               <entry>Normal employees of the IT department</entry>
             </row>
 
             <row>
               <entry><username>charlie</username>, <username>delta</username></entry>
               <entry>The new apprentices of the IT department</entry>
             </row>
 
             <row>
               <entry><username>echo</username>, <username>foxtrott</username>, <username>golf</username>, ...</entry>
               <entry>Ordinary employees</entry>
             </row>
 
             <row>
               <entry><username>able</username>, <username>baker</username>, ...</entry>
               <entry>The current interns</entry>
             </row>
           </tbody>
         </tgroup>
       </informaltable>
 
       <informaltable frame="none" pgwide="1">
         <tgroup cols="2">
           <thead>
             <row>
               <entry>Machine Name(s)</entry>
               <entry>Description</entry>
             </row>
           </thead>
 
           <tbody>
             <row>
               <!--  Names taken from "Good Omens" by Neil Gaiman and Terry
                     Pratchett.  Many thanks for a brilliant book.  -->
 
               <entry><hostid>war</hostid>, <hostid>death</hostid>,
               <hostid>famine</hostid>,
               <hostid>pollution</hostid></entry>
               <entry>Your most important servers.  Only the IT
                 employees are allowed to log onto these
                 machines.</entry>
             </row>
             <row>
               <!-- gluttony was omitted because it was too fat -->
 
               <entry><hostid>pride</hostid>, <hostid>greed</hostid>,
               <hostid>envy</hostid>, <hostid>wrath</hostid>,
               <hostid>lust</hostid>, <hostid>sloth</hostid></entry>
               <entry>Less important servers.  All members of the IT
               department are allowed to login onto these
               machines.</entry>
             </row>
 
             <row>
               <entry><hostid>one</hostid>, <hostid>two</hostid>,
                 <hostid>three</hostid>, <hostid>four</hostid>,
                 ...</entry>
 
               <entry>Ordinary workstations.  Only the
                 <emphasis>real</emphasis> employees are allowed to use
                 these machines.</entry>
             </row>
 
             <row>
               <entry><hostid>trashcan</hostid></entry>
               <entry>A very old machine without any critical data.
                 Even the intern is allowed to use this box.</entry>
             </row>
           </tbody>
         </tgroup>
       </informaltable>
 
       <para>If you tried to implement these restrictions by separately
         blocking each user, you would have to add one
         <literal>-<replaceable>user</replaceable></literal> line to
         each system's <filename>passwd</filename> for each user who is
         not allowed to login onto that system.  If you forget just one
         entry, you could be in trouble.  It may be feasible to do this
         correctly during the initial setup, however you
         <emphasis>will</emphasis> eventually forget to add the lines
         for new users during day-to-day operations.  After all, Murphy
         was an optimist.</para>
 
       <para>Handling this situation with netgroups offers several
         advantages.  Each user need not be handled separately; you
         assign a user to one or more netgroups and allow or forbid
         logins for all members of the netgroup.  If you add a new
         machine, you will only have to define login restrictions for
         netgroups.  If a new user is added, you will only have to add
         the user to one or more netgroups.  Those changes are
         independent of each other: no more <quote>for each combination
         of user and machine do...</quote> If your NIS setup is planned
         carefully, you will only have to modify exactly one central
         configuration file to grant or deny access to machines.</para>
 
       <para>The first step is the initialization of the NIS map
         netgroup.  FreeBSD's &man.ypinit.8; does not create this map by
         default, but its NIS implementation will support it once it has
         been created.  To create an empty map, simply type</para>
 
       <screen>ellington&prompt.root; <userinput>vi /var/yp/netgroup</userinput></screen>
 
       <para>and start adding content.  For our example, we need at
          least four netgroups: IT employees, IT apprentices, normal
          employees and interns.</para>
 
       <programlisting>IT_EMP  (,alpha,test-domain)    (,beta,test-domain)
 IT_APP  (,charlie,test-domain)  (,delta,test-domain)
 USERS   (,echo,test-domain)     (,foxtrott,test-domain) \
         (,golf,test-domain)
 INTERNS (,able,test-domain)     (,baker,test-domain)</programlisting>
 
       <para><literal>IT_EMP</literal>, <literal>IT_APP</literal> etc.
         are the names of the netgroups.  Each bracketed group adds
         one or more user accounts to it.  The three fields inside a
         group are:</para>
 
       <orderedlist>
         <listitem>
           <para>The name of the host(s) where the following items are
             valid.  If you do not specify a hostname, the entry is
             valid on all hosts.  If you do specify a hostname, you
             will enter a realm of darkness, horror and utter confusion.</para>
         </listitem>
 
         <listitem>
           <para>The name of the account that belongs to this
             netgroup.</para>
         </listitem>
 
         <listitem>
           <para>The NIS domain for the account.  You can import
             accounts from other NIS domains into your netgroup if you
             are one of the unlucky fellows with more than one NIS
             domain.</para>
         </listitem>
       </orderedlist>
 
       <para>Each of these fields can contain wildcards.  See
         &man.netgroup.5; for details.</para>
 
       <note>
         <indexterm><primary>netgroups</primary></indexterm>
         <para>Netgroup names longer than 8 characters should not be
           used, especially if you have machines running other
           operating systems within your NIS domain.  The names are
           case sensitive; using capital letters for your netgroup
           names is an easy way to distinguish between user, machine
           and netgroup names.</para>
 
         <para>Some NIS clients (other than FreeBSD) cannot handle
           netgroups with a large number of entries.  For example, some
           older versions of &sunos; start to cause trouble if a netgroup
           contains more than 15 <emphasis>entries</emphasis>.  You can
           circumvent this limit by creating several sub-netgroups with
           15 users or less and a real netgroup that consists of the
           sub-netgroups:</para>
 
         <programlisting>BIGGRP1  (,joe1,domain)  (,joe2,domain)  (,joe3,domain) [...]
 BIGGRP2  (,joe16,domain)  (,joe17,domain) [...]
 BIGGRP3  (,joe31,domain)  (,joe32,domain)
 BIGGROUP  BIGGRP1 BIGGRP2 BIGGRP3</programlisting>
 
         <para>You can repeat this process if you need more than 225
           users within a single netgroup.</para>
       </note>
 
       <para>Activating and distributing your new NIS map is
         easy:</para>
 
       <screen>ellington&prompt.root; <userinput>cd /var/yp</userinput>
 ellington&prompt.root; <userinput>make</userinput></screen>
 
       <para>This will generate the three NIS maps
         <filename>netgroup</filename>,
         <filename>netgroup.byhost</filename> and
         <filename>netgroup.byuser</filename>.  Use &man.ypcat.1; to
         check if your new NIS maps are available:</para>
 
       <screen>ellington&prompt.user; <userinput>ypcat -k netgroup</userinput>
 ellington&prompt.user; <userinput>ypcat -k netgroup.byhost</userinput>
 ellington&prompt.user; <userinput>ypcat -k netgroup.byuser</userinput></screen>
 
       <para>The output of the first command should resemble the
         contents of <filename>/var/yp/netgroup</filename>.  The second
         command will not produce output if you have not specified
         host-specific netgroups.  The third command can be used to
         get the list of netgroups for a user.</para>
 
       <para>The client setup is quite simple.  To configure the server
         <hostid>war</hostid>, you only have to start
         &man.vipw.8; and replace the line</para>
 
       <programlisting>+:::::::::</programlisting>
 
       <para>with</para>
 
       <programlisting>+@IT_EMP:::::::::</programlisting>
 
       <para>Now, only the data for the users defined in the netgroup
         <literal>IT_EMP</literal> is imported into
         <hostid>war</hostid>'s password database and only
         these users are allowed to login.</para>
 
       <para>Unfortunately, this limitation also applies to the
 	<literal>~</literal> function of the shell and all routines
 	converting between user names and numerical user IDs.  In
 	other words, <command>cd
 	~<replaceable>user</replaceable></command> will not work,
 	<command>ls -l</command> will show the numerical ID instead of
 	the username and <command>find . -user joe -print</command>
 	will fail with <errorname>No such user</errorname>.  To fix
 	this, you will have to import all user entries
 	<emphasis>without allowing them to login onto your
 	servers</emphasis>.</para>
 
       <para>This can be achieved by adding another line to
         <filename>/etc/master.passwd</filename>.  This line should
         contain:</para>
 
       <para><literal>+:::::::::/sbin/nologin</literal>, meaning
         <quote>Import all entries but replace the shell with
         <filename>/sbin/nologin</filename> in the imported
         entries</quote>.  You can replace any field in the
         <literal>passwd</literal> entry by placing a default value in
         your <filename>/etc/master.passwd</filename>.</para>
 
       <!-- Been there, done that, got the scars to prove it - ue -->
       <warning>
         <para>Make sure that the line
         <literal>+:::::::::/sbin/nologin</literal> is placed after
         <literal>+@IT_EMP:::::::::</literal>.  Otherwise, all user
         accounts imported from NIS will have <filename>/sbin/nologin</filename> as their
         login shell.</para>
       </warning>
 
       <para>After this change, you will only have to change one NIS
         map if a new employee joins the IT department.  You could use
         a similar approach for the less important servers by replacing
         the old <literal>+:::::::::</literal> in their local version
         of <filename>/etc/master.passwd</filename> with something like
         this:</para>
 
       <programlisting>+@IT_EMP:::::::::
 +@IT_APP:::::::::
 +:::::::::/sbin/nologin</programlisting>
 
       <para>The corresponding lines for the normal workstations
         could be:</para>
 
       <programlisting>+@IT_EMP:::::::::
 +@USERS:::::::::
 +:::::::::/sbin/nologin</programlisting>
 
       <para>And everything would be fine until there is a policy
         change a few weeks later: The IT department starts hiring
         interns.  The IT interns are allowed to use the normal
         workstations and the less important servers; and the IT
         apprentices are allowed to login onto the main servers.  You
         add a new netgroup <literal>IT_INTERN</literal>, add the new
         IT interns to this netgroup and start to change the
         configuration on each and every machine...  As the old saying
         goes: <quote>Errors in centralized planning lead to global
         mess</quote>.</para>
 
       <para>NIS' ability to create netgroups from other netgroups can
         be used to prevent situations like these.  One possibility
         is the creation of role-based netgroups.  For example, you
         could create a netgroup called
         <literal>BIGSRV</literal> to define the login
         restrictions for the important servers, another netgroup
         called <literal>SMALLSRV</literal> for the less
         important servers and a third netgroup called
         <literal>USERBOX</literal> for the normal
         workstations.  Each of these netgroups contains the netgroups
         that are allowed to login onto these machines.  The new
         entries for your NIS map netgroup should look like this:</para>
 
       <programlisting>BIGSRV    IT_EMP  IT_APP
 SMALLSRV  IT_EMP  IT_APP  ITINTERN
 USERBOX   IT_EMP  ITINTERN USERS</programlisting>
 
       <para>This method of defining login restrictions works
         reasonably well if you can define groups of machines with
         identical restrictions.  Unfortunately, this is the exception
         and not the rule.  Most of the time, you will need the ability
         to define login restrictions on a per-machine basis.</para>
 
       <para>Machine-specific netgroup definitions are the other
         possibility to deal with the policy change outlined above.  In
         this scenario, the <filename>/etc/master.passwd</filename> of
         each box contains two lines starting with <quote>+</quote>.
         The first of them adds a netgroup with the accounts allowed to
         login onto this machine, the second one adds all other
         accounts with <filename>/sbin/nologin</filename> as shell.  It
         is a good idea to use the <quote>ALL-CAPS</quote> version of
         the machine name as the name of the netgroup.  In other words,
         the lines should look like this:</para>
 
       <programlisting>+@<replaceable>BOXNAME</replaceable>:::::::::
 +:::::::::/sbin/nologin</programlisting>
 
       <para>Once you have completed this task for all your machines,
         you will not have to modify the local versions of
         <filename>/etc/master.passwd</filename> ever again.  All
         further changes can be handled by modifying the NIS map.  Here
         is an example of a possible netgroup map for this
         scenario with some additional goodies:</para>
 
       <programlisting># Define groups of users first
 IT_EMP    (,alpha,test-domain)    (,beta,test-domain)
 IT_APP    (,charlie,test-domain)  (,delta,test-domain)
 DEPT1     (,echo,test-domain)     (,foxtrott,test-domain)
 DEPT2     (,golf,test-domain)     (,hotel,test-domain)
 DEPT3     (,india,test-domain)    (,juliet,test-domain)
 ITINTERN  (,kilo,test-domain)     (,lima,test-domain)
 D_INTERNS (,able,test-domain)     (,baker,test-domain)
 #
 # Now, define some groups based on roles
 USERS     DEPT1   DEPT2     DEPT3
 BIGSRV    IT_EMP  IT_APP
 SMALLSRV  IT_EMP  IT_APP    ITINTERN
 USERBOX   IT_EMP  ITINTERN  USERS
 #
 # And a groups for a special tasks
 # Allow echo and golf to access our anti-virus-machine
 SECURITY  IT_EMP  (,echo,test-domain)  (,golf,test-domain)
 #
 # machine-based netgroups
 # Our main servers
 WAR       BIGSRV
 FAMINE    BIGSRV
 # User india needs access to this server
 POLLUTION  BIGSRV  (,india,test-domain)
 #
 # This one is really important and needs more access restrictions
 DEATH     IT_EMP
 #
 # The anti-virus-machine mentioned above
 ONE       SECURITY
 #
 # Restrict a machine to a single user
 TWO       (,hotel,test-domain)
 # [...more groups to follow]</programlisting>
 
       <para>If you are using some kind of database to manage your user
         accounts, you should be able to create the first part of the
         map with your database's report tools.  This way, new users
         will automatically have access to the boxes.</para>
 
       <para>One last word of caution: It may not always be advisable
         to use machine-based netgroups.  If you are deploying a couple of
         dozen or even hundreds of identical machines for student labs,
         you should use role-based netgroups instead of machine-based
         netgroups to keep the size of the NIS map within reasonable
         limits.</para>
     </sect2>
 
     <sect2>
       <title>Important Things to Remember</title>
 
       <para>There are still a couple of things that you will need to do
         differently now that you are in an NIS environment.</para>
 
       <itemizedlist>
         <listitem>
           <para>Every time you wish to add a user to the lab, you
             must add it to the master NIS server <emphasis>only</emphasis>,
             and <emphasis>you must remember to rebuild the NIS
             maps</emphasis>.  If you forget to do this, the new user will
             not be able to login anywhere except on the NIS master.
             For example, if we needed to add a new user
             <username>jsmith</username> to the lab, we would:</para>
 
           <screen>&prompt.root; <userinput>pw useradd jsmith</userinput>
 &prompt.root; <userinput>cd /var/yp</userinput>
 &prompt.root; <userinput>make test-domain</userinput></screen>
 
           <para>You could also run <command>adduser jsmith</command> instead
             of <command>pw useradd jsmith</command>.</para>
         </listitem>
         <listitem>
           <para><emphasis>Keep the administration accounts out of the
             NIS maps</emphasis>.  You do not want to be propagating
             administrative accounts and passwords to machines that
             will have users that should not have access to those
             accounts.</para>
         </listitem>
         <listitem>
           <para><emphasis>Keep the NIS master and slave secure, and
             minimize their downtime</emphasis>.  If somebody either
             hacks or simply turns off these machines, they have
             effectively rendered many people without the ability to
             login to the lab.</para>
 
           <para>This is the chief weakness of any centralized administration
             system.  If you do
             not protect your NIS servers, you will have a lot of angry
             users!</para>
         </listitem>
       </itemizedlist>
     </sect2>
 
     <sect2>
       <title>NIS v1 Compatibility</title>
 
       <para> FreeBSD's <application>ypserv</application> has some
 	support for serving NIS v1 clients.  FreeBSD's NIS
 	implementation only uses the NIS v2 protocol, however other
 	implementations include support for the v1 protocol for
 	backwards compatibility with older systems.  The
 	<application>ypbind</application> daemons supplied with these
 	systems will try to establish a binding to an NIS v1 server
 	even though they may never actually need it (and they may
 	persist in broadcasting in search of one even after they
 	receive a response from a v2 server).  Note that while support
 	for normal client calls is provided, this version of
 	<application>ypserv</application> does not handle v1 map
 	transfer requests; consequently, it cannot be used as a master
 	or slave in conjunction with older NIS servers that only
 	support the v1 protocol.  Fortunately, there probably are not
 	any such servers still in use today.</para>
     </sect2>
 
     <sect2 id="network-nis-server-is-client">
       <title>NIS Servers That Are Also NIS Clients</title>
 
       <para> Care must be taken when running
 	<application>ypserv</application> in a multi-server domain
 	where the server machines are also NIS clients.  It is
 	generally a good idea to force the servers to bind to
 	themselves rather than allowing them to broadcast bind
 	requests and possibly become bound to each other.  Strange
 	failure modes can result if one server goes down and others
 	are dependent upon it.  Eventually all the clients will time
 	out and attempt to bind to other servers, but the delay
 	involved can be considerable and the failure mode is still
 	present since the servers might bind to each other all over
 	again.</para>
 
       <para>You can force a host to bind to a particular server by running
 	<command>ypbind</command> with the <option>-S</option>
 	flag.  If you do not want to do this manually each time you
         reboot your NIS server, you can add the following lines to
         your <filename>/etc/rc.conf</filename>:</para>
 
       <programlisting>nis_client_enable="YES"	# run client stuff as well
 nis_client_flags="-S <replaceable>NIS domain</replaceable>,<replaceable>server</replaceable>"</programlisting>
 
       <para>See &man.ypbind.8; for further information.</para>
     </sect2>
 
     <sect2>
       <title>Password Formats</title>
       <indexterm>
         <primary>NIS</primary>
 	<secondary>password formats</secondary>
       </indexterm>
       <para>One of the most common issues that people run into when trying
 	to implement NIS is password format compatibility.  If your NIS
 	server is using DES encrypted passwords, it will only support
 	clients that are also using DES.  For example, if you have
 	&solaris; NIS clients in your network, then you will almost certainly
 	need to use DES encrypted passwords.</para>
 
       <para>To check which format your servers
 	and clients are using, look at <filename>/etc/login.conf</filename>.
 	If the host is configured to use DES encrypted passwords, then the
 	<literal>default</literal> class will contain an entry like this:</para>
 
       <programlisting>default:\
 	:passwd_format=des:\
 	:copyright=/etc/COPYRIGHT:\
 	[Further entries elided]</programlisting>
 
       <para>Other possible values for the <literal>passwd_format</literal>
 	capability include <literal>blf</literal> and <literal>md5</literal>
 	(for Blowfish and MD5 encrypted passwords, respectively).</para>
 
       <para>If you have made changes to
 	<filename>/etc/login.conf</filename>, you will also need to
 	rebuild the login capability database, which is achieved by
 	running the following command as
 	<username>root</username>:</para>
 
       <screen>&prompt.root; <userinput>cap_mkdb /etc/login.conf</userinput></screen>
 
       <note><para>The format of passwords already in
 	<filename>/etc/master.passwd</filename> will not be updated
 	until a user changes his password for the first time
 	<emphasis>after</emphasis> the login capability database is
 	rebuilt.</para></note>
 
       <para>Next, in order to ensure that passwords are encrypted with
 	the format that you have chosen, you should also check that
 	the <literal>crypt_default</literal> in
 	<filename>/etc/auth.conf</filename> gives precedence to your
 	chosen password format.  To do this, place the format that you
 	have chosen first in the list.  For example, when using DES
 	encrypted passwords, the entry would be:</para>
 
       <programlisting>crypt_default	=	des blf md5</programlisting>
 
       <para>Having followed the above steps on each of the &os; based
 	NIS servers and clients, you can be sure that they all agree
 	on which password format is used within your network.  If you
 	have trouble authenticating on an NIS client, this is a pretty
 	good place to start looking for possible problems.  Remember:
 	if you want to deploy an NIS server for a heterogenous
 	network, you will probably have to use DES on all systems
 	because it is the lowest common standard.</para>
     </sect2>
   </sect1>
 
   <sect1 id="network-dhcp">
     <sect1info>
       <authorgroup>
         <author>
           <firstname>Greg</firstname>
       	  <surname>Sutter</surname>
 	  <contrib>Written by </contrib>
         </author>
       </authorgroup>
     </sect1info>
     <title>Automatic Network Configuration (DHCP)</title>
 
     <sect2>
       <title>What Is DHCP?</title>
       <indexterm>
         <primary>Dynamic Host Configuration Protocol</primary>
         <see>DHCP</see>
       </indexterm>
       <indexterm>
         <primary>Internet Software Consortium (ISC)</primary>
       </indexterm>
 
       <para>DHCP, the Dynamic Host Configuration Protocol, describes
         the means by which a system can connect to a network and obtain the
         necessary information for communication upon that network.  FreeBSD
 	versions prior to 6.0 use the ISC (Internet Software
 	Consortium) DHCP client (&man.dhclient.8;) implementation.
 	Later versions use the OpenBSD <command>dhclient</command>
 	taken from OpenBSD&nbsp;3.7.  All
 	information here regarding <command>dhclient</command> is for
 	use with either of the ISC or OpenBSD DHCP clients. The DHCP
 	server is the one included in the ISC distribution.</para>
     </sect2>
 
     <sect2>
       <title>What This Section Covers</title>
 
       <para>This section describes both the client-side components of the ISC and OpenBSD DHCP client and
         server-side components of the ISC DHCP system.  The
         client-side program, <command>dhclient</command>, comes
         integrated within FreeBSD, and the server-side portion is
         available from the <filename
         role="package">net/isc-dhcp3-server</filename> port.  The
         &man.dhclient.8;, &man.dhcp-options.5;, and
         &man.dhclient.conf.5; manual pages, in addition to the
         references below, are useful resources.</para>
     </sect2>
 
     <sect2>
       <title>How It Works</title>
       <indexterm><primary>UDP</primary></indexterm>
       <para>When <command>dhclient</command>, the DHCP client, is
 	executed on the client machine, it begins broadcasting
 	requests for configuration information.  By default, these
 	requests are on UDP port 68.  The server replies on UDP 67,
 	giving the client an IP address and other relevant network
 	information such as netmask, router, and DNS servers.  All of
 	this information comes in the form of a DHCP
 	<quote>lease</quote> and is only valid for a certain time
 	(configured by the DHCP server maintainer).  In this manner,
 	stale IP addresses for clients no longer connected to the
 	network can be automatically reclaimed.</para>
 
       <para>DHCP clients can obtain a great deal of information from
         the server.  An exhaustive list may be found in
         &man.dhcp-options.5;.</para>
     </sect2>
 
     <sect2>
       <title>FreeBSD Integration</title>
 
       <para>&os; fully integrates the ISC or OpenBSD DHCP client,
         <command>dhclient</command> (according to the &os; version you run).  DHCP client support is provided
         within both the installer and the base system, obviating the need
         for detailed knowledge of network configurations on any network
         that runs a DHCP server.  <command>dhclient</command> has been
         included in all FreeBSD distributions since 3.2.</para>
         <indexterm>
           <primary><application>sysinstall</application></primary>
         </indexterm>
 
         <para>DHCP is supported by
           <application>sysinstall</application>.  When configuring a
           network interface within
           <application>sysinstall</application>, the second question
           asked is: <quote>Do you want to try DHCP configuration of
           the interface?</quote>. Answering affirmatively will
           execute <command>dhclient</command>, and if successful, will
           fill in the network configuration information
           automatically.</para>
 
         <para>There are two things you must do to have your system use
 	  DHCP upon startup:</para>
         <indexterm>
           <primary>DHCP</primary>
           <secondary>requirements</secondary>
         </indexterm>
 	<itemizedlist>
 	  <listitem>
             <para>Make sure that the <devicename>bpf</devicename>
 	      device is compiled into your kernel.  To do this, add
 	      <literal>device bpf</literal> to your kernel
 	      configuration file, and rebuild the kernel.  For more
 	      information about building kernels, see <xref
 	      linkend="kernelconfig">.</para> <para>The
 	      <devicename>bpf</devicename> device is already part of
 	      the <filename>GENERIC</filename> kernel that is supplied
 	      with FreeBSD, so if you do not have a custom kernel, you
 	      should not need to create one in order to get DHCP
 	      working.</para>
 	    <note>
 	      <para>For those who are particularly security conscious,
 	        you should be warned that <devicename>bpf</devicename>
 		is also the device that allows packet sniffers to work
 		correctly (although they still have to be run as
 		<username>root</username>).  <devicename>bpf</devicename>
 		<emphasis>is</emphasis> required to use DHCP, but if
 		you are very sensitive about security, you probably
 		should not add <devicename>bpf</devicename> to your
 		kernel in the expectation that at some point in the
 		future you will be using DHCP.</para>
 	    </note>
 	  </listitem>
           <listitem>
             <para>Edit your <filename>/etc/rc.conf</filename> to
 	      include the following:</para>
 
             <programlisting>ifconfig_fxp0="DHCP"</programlisting>
 
             <note>
               <para>Be sure to replace <literal>fxp0</literal> with the
                 designation for the interface that you wish to dynamically
                  configure, as described in
 		 <xref linkend="config-network-setup">.</para>
             </note>
 
             <para>If you are using a different location for
               <command>dhclient</command>, or if you wish to pass additional
               flags to <command>dhclient</command>, also include the
               following (editing as necessary):</para>
 
             <programlisting>dhcp_program="/sbin/dhclient"
 dhcp_flags=""</programlisting>
           </listitem>
         </itemizedlist>
 
         <indexterm>
           <primary>DHCP</primary>
           <secondary>server</secondary>
         </indexterm>
         <para>The DHCP server, <application>dhcpd</application>, is included
           as part of the <filename
           role="package">net/isc-dhcp3-server</filename> port in the ports
           collection.  This port contains the ISC DHCP server and
           documentation.</para>
     </sect2>
 
     <sect2>
       <title>Files</title>
       <indexterm>
         <primary>DHCP</primary>
         <secondary>configuration files</secondary>
       </indexterm>
       <itemizedlist>
         <listitem><para><filename>/etc/dhclient.conf</filename></para>
           <para><command>dhclient</command> requires a configuration file,
             <filename>/etc/dhclient.conf</filename>.  Typically the file
             contains only comments, the defaults being reasonably sane.  This
             configuration file is described by the &man.dhclient.conf.5;
             manual page.</para>
         </listitem>
 
         <listitem><para><filename>/sbin/dhclient</filename></para>
           <para><command>dhclient</command> is statically linked and
             resides in <filename>/sbin</filename>.  The &man.dhclient.8;
             manual page gives more information about
             <command>dhclient</command>.</para>
         </listitem>
 
         <listitem><para><filename>/sbin/dhclient-script</filename></para>
           <para><command>dhclient-script</command> is the FreeBSD-specific
             DHCP client configuration script.  It is described in
             &man.dhclient-script.8;, but should not need any user
             modification to function properly.</para>
         </listitem>
 
         <listitem><para><filename>/var/db/dhclient.leases</filename></para>
           <para>The DHCP client keeps a database of valid leases in this
             file, which is written as a log.  &man.dhclient.leases.5;
             gives a slightly longer description.</para>
         </listitem>
       </itemizedlist>
     </sect2>
 
     <sect2>
       <title>Further Reading</title>
 
       <para>The DHCP protocol is fully described in
         <ulink url="http://www.freesoft.org/CIE/RFC/2131/">RFC 2131</ulink>.
         An informational resource has also been set up at
         <ulink url="http://www.dhcp.org/"></ulink>.</para>
     </sect2>
 
     <sect2 id="network-dhcp-server">
 	<title>Installing and Configuring a DHCP Server</title>
 
 	<sect3>
 	  <title>What This Section Covers</title>
 
 	  <para>This section provides information on how to configure
 	    a FreeBSD system to act as a DHCP server using the ISC
 	    (Internet Software Consortium) implementation of the DHCP
 	    server.</para>
 
 	  <para>The server is not provided as part of
 	    FreeBSD, and so you will need to install the
 	    <filename role="package">net/isc-dhcp3-server</filename>
 	    port to provide this service.  See <xref linkend="ports"> for
 	    more information on using the Ports Collection.</para>
 	</sect3>
 
 	<sect3>
 	  <title>DHCP Server Installation</title>
 	  <indexterm>
 	    <primary>DHCP</primary>
 	    <secondary>installation</secondary>
 	  </indexterm>
 	  <para>In order to configure your FreeBSD system as a DHCP
 	    server, you will need to ensure that the &man.bpf.4;
 	    device is compiled into your kernel.  To do this, add
 	    <literal>device bpf</literal> to your kernel
 	    configuration file, and rebuild the kernel.  For more
 	    information about building kernels, see <xref
 	    linkend="kernelconfig">.</para>
 
 	  <para>The <devicename>bpf</devicename> device is already
 	    part of the <filename>GENERIC</filename> kernel that is
 	    supplied with FreeBSD, so you do not need to create a custom
 	    kernel in order to get DHCP working.</para>
 
 	    <note>
 	      <para>Those who are particularly security conscious
 	        should note that <devicename>bpf</devicename>
 		is also the device that allows packet sniffers to work
 		correctly (although such programs still need privileged
 		access).  <devicename>bpf</devicename>
 		<emphasis>is</emphasis> required to use DHCP, but if
 		you are very sensitive about security, you probably
 		should not include <devicename>bpf</devicename> in your
 		kernel purely because you expect to use DHCP at some
 		point in the future.</para>
 	    </note>
 
 	  <para>The next thing that you will need to do is edit the sample
 	    <filename>dhcpd.conf</filename> which was installed by the
 	    <filename role="package">net/isc-dhcp3-server</filename> port.
 	    By default, this will be
 	    <filename>/usr/local/etc/dhcpd.conf.sample</filename>, and you
 	    should copy this to
 	    <filename>/usr/local/etc/dhcpd.conf</filename> before proceeding
 	    to make changes.</para>
 	</sect3>
 
 	<sect3>
 	  <title>Configuring the DHCP Server</title>
 	  <indexterm>
 	    <primary>DHCP</primary>
 	    <secondary>dhcpd.conf</secondary>
 	  </indexterm>
 	  <para><filename>dhcpd.conf</filename> is
 	    comprised of declarations regarding subnets and hosts, and is
 	    perhaps most easily explained using an example :</para>
 
 	  <programlisting>option domain-name "example.com";<co id="domain-name">
 option domain-name-servers 192.168.4.100;<co id="domain-name-servers">
 option subnet-mask 255.255.255.0;<co id="subnet-mask">
 
 default-lease-time 3600;<co id="default-lease-time">
 max-lease-time 86400;<co id="max-lease-time">
 ddns-update-style none;<co id="ddns-update-style">
 
 subnet 192.168.4.0 netmask 255.255.255.0 {
   range 192.168.4.129 192.168.4.254;<co id="range">
   option routers 192.168.4.1;<co id="routers">
 }
 
 host mailhost {
   hardware ethernet 02:03:04:05:06:07;<co id="hardware">
   fixed-address mailhost.example.com;<co id="fixed-address">
 }</programlisting>
 
 	  <calloutlist>
 	    <callout arearefs="domain-name">
 	      <para>This option specifies the domain that will be provided
 		to clients as the default search domain.  See
 		&man.resolv.conf.5; for more information on what this
 		means.</para>
 	    </callout>
 
 	    <callout arearefs="domain-name-servers">
 	      <para>This option specifies a comma separated list of DNS
 		servers that the client should use.</para>
 	    </callout>
 
 	    <callout arearefs="subnet-mask">
 	      <para>The netmask that will be provided to clients.</para>
 	    </callout>
 
 	    <callout arearefs="default-lease-time">
 	      <para>A client may request a specific length of time that a
 		lease will be valid.  Otherwise the server will assign
 		a lease with this expiry value (in seconds).</para>
 	    </callout>
 
 	    <callout arearefs="max-lease-time">
 	      <para>This is the maximum length of time that the server will
 		lease for.  Should a client request a longer lease, a lease
 		will be issued, although it will only be valid for
 		<literal>max-lease-time</literal> seconds.</para>
 	    </callout>
 
 	    <callout arearefs="ddns-update-style">
 	      <para>This option specifies whether the DHCP server should
 		attempt to update DNS when a lease is accepted or released.
 		In the ISC implementation, this option is
 		<emphasis>required</emphasis>.</para>
 	    </callout>
 
 	    <callout arearefs="range">
 	      <para>This denotes which IP addresses should be used in
 		the pool reserved for allocating to clients.  IP
 		addresses between, and including, the ones stated are
 		handed out to clients.</para>
 	    </callout>
 
 	    <callout arearefs="routers">
 	      <para>Declares the default gateway that will be provided to
 		clients.</para>
 	    </callout>
 
 	    <callout arearefs="hardware">
 	      <para>The hardware MAC address of a host (so that the DHCP server
 		can recognize a host when it makes a request).</para>
 	    </callout>
 
 	    <callout arearefs="fixed-address">
 	      <para>Specifies that the host should always be given the
 		same IP address.  Note that using a hostname is
 		correct here, since the DHCP server will resolve the
 		hostname itself before returning the lease
 		information.</para>
 	    </callout>
 	  </calloutlist>
 
 	  <para>Once you have finished writing your
 	    <filename>dhcpd.conf</filename>,
 	    you should enable the DHCP server in
 	    <filename>/etc/rc.conf</filename>, i.e. by adding:</para>
 
 	  <programlisting>dhcpd_enable="YES"
 dhcpd_ifaces="dc0"</programlisting>
 
 	  <para>Replace the <literal>dc0</literal> interface name with the
 	    interface (or interfaces, separated by whitespace) that your DHCP
 	    server should listen on for DHCP client requests.</para>
 
 	  <para>Then, you can proceed to start the server by issuing the
 	    following command:</para>
 
 	  <screen>&prompt.root; <userinput>/usr/local/etc/rc.d/isc-dhcpd.sh start</userinput></screen>
 
 	  <para>Should you need to make changes to the configuration of your
 	    server in the future, it is important to note that sending a
 	    <literal>SIGHUP</literal> signal to
 	    <application>dhcpd</application> does <emphasis>not</emphasis>
 	    result in the configuration being reloaded, as it does with most
 	    daemons.  You will need to send a <literal>SIGTERM</literal>
 	    signal to stop the process, and then restart it using the command
 	    above.</para>
 	</sect3>
 
 	<sect3>
 	  <title>Files</title>
 	  <indexterm>
 	    <primary>DHCP</primary>
 	    <secondary>configuration files</secondary>
 	  </indexterm>
 	  <itemizedlist>
 	    <listitem><para><filename>/usr/local/sbin/dhcpd</filename></para>
 	      <para><application>dhcpd</application> is statically linked and
 		resides in <filename>/usr/local/sbin</filename>.  The
 		&man.dhcpd.8; manual page installed with the
 		port gives more information about
 		<application>dhcpd</application>.</para>
 	    </listitem>
 
 	    <listitem><para><filename>/usr/local/etc/dhcpd.conf</filename></para>
 	      <para><application>dhcpd</application> requires a configuration
 		file, <filename>/usr/local/etc/dhcpd.conf</filename> before it
 		will start providing service to clients.  This file needs to
 		contain all the information that should be provided to clients
 		that are being serviced, along with information regarding the
 		operation of the server.  This configuration file is described
 		by the &man.dhcpd.conf.5; manual page installed
 		by the port.</para>
 	    </listitem>
 
 	    <listitem><para><filename>/var/db/dhcpd.leases</filename></para>
 	      <para>The DHCP server keeps a database of leases it has issued
 		in this file, which is written as a log.  The manual page
 		&man.dhcpd.leases.5;, installed by the port
 		gives a slightly longer description.</para>
 	    </listitem>
 
 	    <listitem><para><filename>/usr/local/sbin/dhcrelay</filename></para>
 	      <para><application>dhcrelay</application> is used in advanced
 		environments where one DHCP server forwards a request from a
 		client to another DHCP server on a separate network.  If you
 		require this functionality, then install the <filename
 		role="package">net/isc-dhcp3-relay</filename> port.  The
 		&man.dhcrelay.8; manual page provided with the
 		port contains more detail.</para>
 	    </listitem>
 	  </itemizedlist>
 	</sect3>
 
       </sect2>
 
   </sect1>
 
   <sect1 id="network-dns">
     <sect1info>
       <authorgroup>
         <author>
           <firstname>Chern</firstname>
           <surname>Lee</surname>
           <contrib>Contributed by </contrib>
         </author>
 
 	<author>
 	  <firstname>Tom</firstname>
 	  <surname>Rhodes</surname>
 	</author>
 
 	<author>
 	  <firstname>Daniel</firstname>
 	  <surname>Gerzo</surname>
 	</author>
       </authorgroup>
     </sect1info>
     <title>Domain Name System (<acronym>DNS</acronym>)</title>
 
     <sect2>
       <title>Overview</title>
       <indexterm><primary>BIND</primary></indexterm>
 
       <para>&os; utilizes, by default, a version of BIND (Berkeley
 	Internet Name Domain), which is the most common implementation
 	of the <acronym>DNS</acronym> protocol. <acronym>DNS</acronym>
 	is the protocol through which names are mapped to
 	<acronym>IP</acronym> addresses, and vice versa.  For example, a
 	query for <hostid role="fqdn">www.FreeBSD.org</hostid> will
 	receive a reply with the <acronym>IP</acronym> address of The
 	&os; Project's web server, whereas, a query for <hostid
 	role="fqdn">ftp.FreeBSD.org</hostid> will return the
 	<acronym>IP</acronym> address of the corresponding
 	<acronym>FTP</acronym> machine.  Likewise, the opposite can
 	happen.  A query for an <acronym>IP</acronym> address can
 	resolve its hostname.  It is not necessary to run a name server
 	to perform <acronym>DNS</acronym> lookups on a system.</para>
 
       <para>&os; currently comes with <acronym>BIND</acronym>9
 	<acronym>DNS</acronym> server software by default.  Our
 	installation provides enhanced security features, a new file
 	system layout and automated &man.chroot.8; configuration.</para>
 
       <indexterm><primary>DNS</primary></indexterm>
       <para><acronym>DNS</acronym> is coordinated across the Internet
 	through a somewhat complex system of authoritative root, Top
 	Level Domain (<acronym>TLD</acronym>), and other smaller-scale
 	name servers which host and cache individual domain
 	information.</para>
 
       <para>Currently, BIND is maintained by the
 	Internet Software Consortium
 	<ulink url="http://www.isc.org/"></ulink>.</para>
     </sect2>
 
     <sect2>
       <title>Terminology</title>
 
       <para>To understand this document, some terms related to
 	<acronym>DNS</acronym> must be understood.</para>
 
       <indexterm><primary>resolver</primary></indexterm>
       <indexterm><primary>reverse DNS</primary></indexterm>
       <indexterm><primary>root zone</primary></indexterm>
 
       <informaltable frame="none" pgwide="1">
 	<tgroup cols="2">
 	  <colspec colwidth="1*">
 	  <colspec colwidth="3*">
 
 	  <thead>
 	    <row>
 	      <entry>Term</entry>
 	      <entry>Definition</entry>
 	    </row>
 	  </thead>
 
 	  <tbody>
 	    <row>
 	      <entry>Forward <acronym>DNS</acronym></entry>
 	      <entry>Mapping of hostnames to IP addresses.</entry>
 	    </row>
 
 	    <row>
 	      <entry>Origin</entry>
 	      <entry>Refers to the domain covered in a particular zone
 		file.</entry>
 	    </row>
 
 	    <row>
 	      <entry><application>named</application>, BIND, name server</entry>
 	      <entry>Common names for the BIND name server package within
 		&os;.</entry>
 	    </row>
 
 	    <row>
 	      <entry>Resolver</entry>
 	      <entry>A system process through which a
 		machine queries a name server for zone information.</entry>
 	    </row>
 
 	    <row>
 	      <entry>Reverse <acronym>DNS</acronym></entry>
 	      <entry>The opposite of forward <acronym>DNS</acronym>;
 		mapping of <acronym>IP</acronym> addresses to
 		hostnames.</entry>
 	    </row>
 
 	    <row>
 	      <entry>Root zone</entry>
 
 	      <entry>The beginning of the Internet zone hierarchy.
 		All zones fall under the root zone, similar to how
 		all files in a file system fall under the root
 		directory.</entry>
 	    </row>
 
 	    <row>
 	      <entry>Zone</entry>
 	      <entry>An individual domain, subdomain, or portion of the
 		<acronym>DNS</acronym> administered by the same
 		authority.</entry>
 	    </row>
 	  </tbody>
 	</tgroup>
       </informaltable>
 
       <indexterm>
 	<primary>zones</primary>
 	<secondary>examples</secondary>
       </indexterm>
 
       <para>Examples of zones:</para>
 
       <itemizedlist>
 	<listitem>
 	  <para><hostid>.</hostid> is the root zone.</para>
 	</listitem>
 
 	<listitem>
 	  <para><hostid>org.</hostid> is a Top Level Domain
 	    (<acronym>TLD</acronym>) under the root zone.</para>
 	</listitem>
 
 	<listitem>
 	  <para><hostid role="domainname">example.org.</hostid> is a
 	    zone under the <hostid>org.</hostid>
 	    <acronym>TLD</acronym>.</para>
 	</listitem>
 
 	<listitem>
 	  <para><hostid>1.168.192.in-addr.arpa</hostid> is a zone
 	    referencing all <acronym>IP</acronym> addresses which fall
 	    under the <hostid role="ipaddr">192.168.1.*</hostid>
 	    <acronym>IP</acronym> space.</para>
 	</listitem>
       </itemizedlist>
 
       <para>As one can see, the more specific part of a hostname appears
 	to its left.  For example, <hostid
 	role="domainname">example.org.</hostid> is more specific than
 	<hostid>org.</hostid>, as <hostid>org.</hostid> is more specific
 	than the root zone.  The layout of each part of a hostname is
 	much like a file system: the
 	<filename role="directory">/dev</filename> directory falls
 	within the root, and so on.</para>
     </sect2>
 
     <sect2>
       <title>Reasons to Run a Name Server</title>
 
       <para>Name servers usually come in two forms: an authoritative
 	name server, and a caching name server.</para>
 
       <para>An authoritative name server is needed when:</para>
 
       <itemizedlist>
 	<listitem>
 	  <para>One wants to serve <acronym>DNS</acronym> information to
 	    the world, replying authoritatively to queries.</para>
 	</listitem>
 
 	<listitem>
 	  <para>A domain, such as <hostid
 	    role="domainname">example.org</hostid>, is registered and
 	    <acronym>IP</acronym> addresses need to be assigned to
 	    hostnames under it.</para>
 	</listitem>
 
 	<listitem>
 	  <para>An <acronym>IP</acronym> address block requires reverse
 	    <acronym>DNS</acronym> entries (<acronym>IP</acronym> to
 	    hostname).</para>
 	</listitem>
 
 	<listitem>
 	  <para>A backup or second name server, called a slave, will
 	    reply to queries.</para>
 	</listitem>
       </itemizedlist>
 
       <para>A caching name server is needed when:</para>
 
       <itemizedlist>
 	<listitem>
 	  <para>A local <acronym>DNS</acronym> server may cache and
 	    respond more quickly than querying an outside name
 	    server.</para>
 	</listitem>
       </itemizedlist>
 
       <para>When one queries for <hostid
 	role="fqdn">www.FreeBSD.org</hostid>, the resolver usually
 	queries the uplink <acronym>ISP</acronym>'s name server, and
 	retrieves the reply.  With a local, caching
 	<acronym>DNS</acronym> server, the query only has to be made
 	once to the outside world by the caching <acronym>DNS</acronym>
 	server.  Every additional query will not have to look to the
 	outside of the local network, since the information is cached
 	locally.</para>
     </sect2>
 
     <sect2>
       <title>How It Works</title>
       <para>In &os;, the BIND daemon is called
 	<application>named</application> for obvious reasons.</para>
 
       <informaltable frame="none" pgwide="1">
 	<tgroup cols="2">
 	  <thead>
 	    <row>
 	      <entry>File</entry>
 	      <entry>Description</entry>
 	    </row>
 	  </thead>
 
 	  <tbody>
 	    <row>
 	      <entry>&man.named.8;</entry>
 	      <entry>The BIND daemon.</entry>
 	    </row>
 
 	    <row>
 	      <entry>&man.rndc.8;</entry>
 	      <entry>Name server control utility.</entry>
 	    </row>
 
 	    <row>
 	      <entry><filename role="directory">/etc/namedb</filename></entry>
 	      <entry>Directory where BIND zone information resides.</entry>
 	    </row>
 
 	    <row>
 	      <entry><filename>/etc/namedb/named.conf</filename></entry>
 	      <entry>Configuration file of the daemon.</entry>
 	    </row>
 	  </tbody>
 	</tgroup>
       </informaltable>
 
       <para>Depending on how a given zone is configured on the server,
 	the files related to that zone can be found in the <filename
 	role="directory">master</filename>, <filename
 	role="directory">slave</filename>, or <filename
 	role="directory">dynamic</filename> subdirectories of the
 	<filename role="directory">/etc/namedb</filename> directory.
 	These files contain the <acronym>DNS</acronym> information that
 	will be given out by the name server in response to queries.</para>
     </sect2>
 
     <sect2>
       <title>Starting BIND</title>
       <indexterm>
 	<primary>BIND</primary>
 	<secondary>starting</secondary>
       </indexterm>
 
       <para>Since BIND is installed by default, configuring it all is
 	relatively simple.</para>
 
       <para>The default <application>named</application> configuration
 	is that of a basic resolving name server, ran in a
 	&man.chroot.8; environment.  To start the server one time with
 	this configuration, use the following command:</para>
 
       <screen>&prompt.root; <userinput>/etc/rc.d/named forcestart</userinput></screen>
 
       <para>To ensure the <application>named</application> daemon is
          started at boot each time, put the following line into the
          <filename>/etc/rc.conf</filename>:</para>
 
       <programlisting>named_enable="YES"</programlisting>
 
       <para>There are obviously many configuration options for
 	<filename>/etc/namedb/named.conf</filename> that are beyond the
 	scope of this document.  However, if you are interested in the
 	startup options for <application>named</application> on &os;,
 	take a look at the
 	<literal>named_<replaceable>*</replaceable></literal> flags in
 	<filename>/etc/defaults/rc.conf</filename> and consult the
 	&man.rc.conf.5; manual page.  The
 	<xref linkend="configtuning-rcd"> section is also a good read.</para>
     </sect2>
 
     <sect2>
       <title>Configuration Files</title>
       <indexterm>
 	<primary>BIND</primary>
 	<secondary>configuration files</secondary>
       </indexterm>
 
       <para>Configuration files for <application>named</application>
 	currently reside in
 	<filename role="directory">/etc/namedb</filename> directory and
 	will need modification before use, unless all that is needed is
 	a simple resolver.  This is where most of the configuration will
 	be performed.</para>
 
       <sect3>
 	<title>Using <command>make-localhost</command></title>
 
 	<para>To configure a master zone for the localhost visit the
 	  <filename role="directory">/etc/namedb</filename> directory
 	  and run the following command:</para>
 
 	<screen>&prompt.root; <userinput>sh make-localhost</userinput></screen>
 
 	<para>If all went well, a new file should exist in the
 	  <filename class="directory">master</filename> subdirectory.
 	  The filenames should be <filename>localhost.rev</filename> for
 	  the local domain name and <filename>localhost-v6.rev</filename>
 	  for <acronym>IPv6</acronym> configurations.  As the default
 	  configuration file, required information will
 	  be present in the <filename>named.conf</filename> file.</para>
       </sect3>
 
       <sect3>
 	<title><filename>/etc/namedb/named.conf</filename></title>
 
 	<programlisting>// &dollar;FreeBSD&dollar;
 //
 // Refer to the named.conf(5) and named(8) man pages, and the documentation
 // in /usr/share/doc/bind9 for more details.
 //
 // If you are going to set up an authoritative server, make sure you
 // understand the hairy details of how DNS works.  Even with
 // simple mistakes, you can break connectivity for affected parties,
 // or cause huge amounts of useless Internet traffic.
 
 options {
 	directory	"/etc/namedb";
 	pid-file	"/var/run/named/pid";
 	dump-file	"/var/dump/named_dump.db";
 	statistics-file	"/var/stats/named.stats";
 
 // If named is being used only as a local resolver, this is a safe default.
 // For named to be accessible to the network, comment this option, specify
 // the proper IP address, or delete this option.
 	listen-on	{ 127.0.0.1; };
 
 // If you have IPv6 enabled on this system, uncomment this option for
 // use as a local resolver.  To give access to the network, specify
 // an IPv6 address, or the keyword "any".
 //	listen-on-v6	{ ::1; };
 
 // In addition to the "forwarders" clause, you can force your name
 // server to never initiate queries of its own, but always ask its
 // forwarders only, by enabling the following line:
 //
 //	forward only;
 
 // If you've got a DNS server around at your upstream provider, enter
 // its IP address here, and enable the line below.  This will make you
 // benefit from its cache, thus reduce overall DNS traffic in the Internet.
 /*
 	forwarders {
 		127.0.0.1;
 	};
 */</programlisting>
 
 	<para>Just as the comment says, to benefit from an uplink's
 	  cache, <literal>forwarders</literal> can be enabled here.
 	  Under normal circumstances, a name server will recursively
 	  query the Internet looking at certain name servers until it
 	  finds the answer it is looking for.  Having this enabled will
 	  have it query the uplink's name server (or name server
 	  provided) first, taking advantage of its cache.  If the uplink
 	  name server in question is a heavily trafficked, fast name
 	  server, enabling this may be worthwhile.</para>
 
 	<warning>
 	  <para><hostid role="ipaddr">127.0.0.1</hostid> will
 	    <emphasis>not</emphasis> work here.  Change this
 	    <acronym>IP</acronym> address to a name server at your
 	    uplink.</para>
 	</warning>
 
 	<programlisting>	/*
 	 * If there is a firewall between you and nameservers you want
 	 * to talk to, you might need to uncomment the query-source
 	 * directive below.  Previous versions of BIND always asked
 	 * questions using port 53, but BIND versions 8 and later
 	 * use a pseudo-random unprivileged UDP port by default.
 	 */
 	 // query-source address * port 53;
 };
 
 // If you enable a local name server, don't forget to enter 127.0.0.1
 // first in your /etc/resolv.conf so this server will be queried.
 // Also, make sure to enable it in /etc/rc.conf.
 
 zone "." {
 	type hint;
 	file "named.root";
 };
 
 zone "0.0.127.IN-ADDR.ARPA" {
 	type master;
 	file "master/localhost.rev";
 };
 
 // RFC 3152
 zone "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA" {
 	type master;
 	file "master/localhost-v6.rev";
 };
 
 // NB: Do not use the IP addresses below, they are faked, and only
 // serve demonstration/documentation purposes!
 //
 // Example slave zone config entries.  It can be convenient to become
 // a slave at least for the zone your own domain is in.  Ask
 // your network administrator for the IP address of the responsible
 // primary.
 //
 // Never forget to include the reverse lookup (IN-ADDR.ARPA) zone!
 // (This is named after the first bytes of the IP address, in reverse
 // order, with ".IN-ADDR.ARPA" appended.)
 //
 // Before starting to set up a primary zone, make sure you fully
 // understand how DNS and BIND works.  There are sometimes
 // non-obvious pitfalls.  Setting up a slave zone is simpler.
 //
 // NB: Don't blindly enable the examples below. :-)  Use actual names
 // and addresses instead.
 
 /* An example master zone
 zone "example.net" {
 	type master;
 	file "master/example.net";
 };
 */
 
 /* An example dynamic zone
 key "exampleorgkey" {
 	algorithm hmac-md5;
 	secret "sf87HJqjkqh8ac87a02lla==";
 };
 zone "example.org" {
 	type master;
 	allow-update {
 		key "exampleorgkey";
 	};
 	file "dynamic/example.org";
 };
 */
 
 /* Examples of forward and reverse slave zones
 zone "example.com" {
 	type slave;
 	file "slave/example.com";
 	masters {
 		192.168.1.1;
 	};
 };
 zone "1.168.192.in-addr.arpa" {
 	type slave;
 	file "slave/1.168.192.in-addr.arpa";
 	masters {
 		192.168.1.1;
 	};
 };
 */</programlisting>
 
 	<para>In <filename>named.conf</filename>, these are examples of
 	  slave entries for a forward and reverse zone.</para>
 
 	<para>For each new zone served, a new zone entry must be added
 	  to <filename>named.conf</filename>.</para>
 
 	<para>For example, the simplest zone entry for
 	  <hostid role="domainname">example.org</hostid> can look
 	  like:</para>
 
 	<programlisting>zone "example.org" {
 	type master;
 	file "master/example.org";
 };</programlisting>
 
 	<para>The zone is a master, as indicated by the
 	  <option>type</option> statement, holding its zone information
 	  in <filename>/etc/namedb/master/example.org</filename>
 	  indicated by the <option>file</option> statement.</para>
 
 	<programlisting>zone "example.org" {
 	type slave;
 	file "slave/example.org";
 };</programlisting>
 
 	<para>In the slave case, the zone information is transferred
 	  from the master name server for the particular zone, and saved
 	  in the file specified.  If and when the master server dies or
 	  is unreachable, the slave name server will have the
 	  transferred zone information and will be able to serve
 	  it.</para>
       </sect3>
 
       <sect3>
 	<title>Zone Files</title>
 	<indexterm>
 	  <primary>BIND</primary>
 	  <secondary>zone files</secondary>
 	</indexterm>
 	
 	<para>An example master zone file for <hostid
 	  role="domainname">example.org</hostid> (existing within
 	  <filename>/etc/namedb/master/example.org</filename>) is as
 	  follows:</para>
 
 	<programlisting>&dollar;TTL 3600        ; 1 hour
 example.org.    IN      SOA      ns1.example.org. admin.example.org. (
                                 2006051501      ; Serial
                                 10800           ; Refresh
                                 3600            ; Retry
                                 604800          ; Expire
                                 86400           ; Minimum TTL
                         )
 
 ; DNS Servers
                 IN      NS      ns1.example.org.
                 IN      NS      ns2.example.org.
 
 ; MX Records
                 IN      MX 10   mx.example.org.
                 IN      MX 20   mail.example.org.
 
                 IN      A       192.168.1.1
 
 ; Machine Names
 localhost       IN      A       127.0.0.1
 ns1             IN      A       192.168.1.2
 ns2             IN      A       192.168.1.3
 mx              IN      A       192.168.1.4
 mail            IN      A       192.168.1.5
 
 ; Aliases
 www             IN      CNAME   @</programlisting>
 
         <para>
           Note that every hostname ending in a <quote>.</quote> is an
           exact hostname, whereas everything without a trailing
           <quote>.</quote> is referenced to the origin.  For example,
           <literal>www</literal> is translated into
           <literal>www.<replaceable>origin</replaceable></literal>.
           In our fictitious zone file, our origin is
           <hostid>example.org.</hostid>, so <literal>www</literal>
           would translate to <hostid>www.example.org.</hostid>
         </para>
 
         <para>
           The format of a zone file follows:
         </para>
         <programlisting>recordname      IN recordtype   value</programlisting>
 
 	<indexterm>
 	  <primary>DNS</primary>
 	  <secondary>records</secondary>
 	</indexterm>
         <para>
           The most commonly used DNS records:
         </para>
 
 	<variablelist>
 	  <varlistentry>
 	    <term>SOA</term>
 
 	    <listitem><para>start of zone authority</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term>NS</term>
 
 	    <listitem><para>an authoritative name server</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term>A</term>
 
 	    <listitem><para>a host address</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term>CNAME</term>
 
 	    <listitem><para>the canonical name for an alias</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term>MX</term>
 
 	    <listitem><para>mail exchanger</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term>PTR</term>
 
 	    <listitem><para>a domain name pointer (used in reverse DNS)
 	      </para></listitem>
 	  </varlistentry>
 	</variablelist>
 
         <programlisting>
 example.org. IN SOA ns1.example.org. admin.example.org. (
                         2006051501      ; Serial
                         10800           ; Refresh after 3 hours
                         3600            ; Retry after 1 hour
                         604800          ; Expire after 1 week
                         86400 )         ; Minimum TTL of 1 day</programlisting>
 
 
 
 	<variablelist>
 	  <varlistentry>
 	    <term><hostid role="domainname">example.org.</hostid></term>
 
 	    <listitem><para>the domain name, also the origin for this
 		zone file.</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term><hostid role="fqdn">ns1.example.org.</hostid></term>
 
 	    <listitem><para>the primary/authoritative name server for this
 		zone.</para></listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term><literal>admin.example.org.</literal></term>
 
 	    <listitem><para>the responsible person for this zone,
 		email address with <quote>@</quote>
           replaced.  (<email>admin@example.org</email> becomes
 		<literal>admin.example.org</literal>)</para>
 	    </listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term><literal>2006051501</literal></term>
 
 	      <listitem><para>the serial number of the file.  This
 		  must be incremented each time the zone file is
 		  modified.  Nowadays, many admins prefer a
 		  <literal>yyyymmddrr</literal> format for the serial
 		  number.  <literal>2006051501</literal> would mean
 		  last modified 05/15/2006, the latter
 		  <literal>01</literal> being the first time the zone
 		  file has been modified this day.  The serial number
 		  is important as it alerts slave name servers for a
 		  zone when it is updated.</para>
 	      </listitem>
 	  </varlistentry>
 	</variablelist>
 
         <programlisting>
        IN NS           ns1.example.org.</programlisting>
 
         <para>
           This is an NS entry.  Every name server that is going to reply
           authoritatively for the zone must have one of these entries.
         </para>
 
         <programlisting>
 localhost       IN      A       127.0.0.1
 ns1             IN      A       192.168.1.2
 ns2             IN      A       192.168.1.3
 mx              IN      A       192.168.1.4
 mail            IN      A       192.168.1.5</programlisting>
 
         <para>
           The A record indicates machine names.  As seen above,
           <hostid role="fqdn">ns1.example.org</hostid> would resolve
           to <hostid role="ipaddr">192.168.1.2</hostid>.
         </para>
 
         <programlisting>
                 IN      A       192.168.1.1</programlisting>
 
 	<para>This line assigns IP address
 	  <hostid role="ipaddr">192.168.1.1</hostid> to the current origin,
 	  in this case <hostid role="domainname">example.org</hostid>.</para>
 
         <programlisting>
 www             IN CNAME        @</programlisting>
 
         <para>
           The canonical name record is usually used for giving aliases
           to a machine.  In the example, <hostid>www</hostid> is
           aliased to the <quote>master</quote> machine which name equals
           to domain name <hostid role="domainname">example.org</hostid>
           (<hostid role="ipaddr">192.168.1.1</hostid>).
           CNAMEs can be used to provide alias
           hostnames, or round robin one hostname among multiple
           machines.
         </para>
 
 	<indexterm>
 	  <primary>MX record</primary>
 	</indexterm>
 
         <programlisting>
                IN MX   10      mail.example.org.</programlisting>
 
         <para>
           The MX record indicates which mail
           servers are responsible for handling incoming mail for the
           zone.  <hostid role="fqdn">mail.example.org</hostid> is the
           hostname of the mail server, and 10 being the priority of
           that mail server.
         </para>
 
         <para>
           One can have several mail servers, with priorities of 10,
           20 and so on.  A mail server attempting to deliver to <hostid
           role="domainname">example.org</hostid> would first try the
           highest priority MX (the record with the lowest priority
 	  number), then the second highest, etc, until the mail can be
 	  properly delivered.
         </para>
 
         <para>
           For in-addr.arpa zone files (reverse DNS), the same format is
           used, except with PTR entries instead of
 	  A or CNAME.
         </para>
 
         <programlisting>$TTL 3600
 
 1.168.192.in-addr.arpa. IN SOA ns1.example.org. admin.example.org. (
                         2006051501      ; Serial
                         10800           ; Refresh
                         3600            ; Retry
                         604800          ; Expire
                         3600 )          ; Minimum
 
         IN      NS      ns1.example.org.
         IN      NS      ns2.example.org.
 
 1       IN      PTR     example.org.
 2       IN      PTR     ns1.example.org.
 3       IN      PTR     ns2.example.org.
 4       IN      PTR     mx.example.org.
 5       IN      PTR     mail.example.org.</programlisting>
 
         <para>This file gives the proper IP address to hostname
           mappings of our above fictitious domain.</para>
       </sect3>
     </sect2>
 
     <sect2>
       <title>Caching Name Server</title>
       <indexterm>
         <primary>BIND</primary>
         <secondary>caching name server</secondary>
       </indexterm>
 
       <para>A caching name server is a name server that is not
         authoritative for any zones.  It simply asks queries of its
         own, and remembers them for later use.  To set one up, just
         configure the name server as usual, omitting any inclusions of
         zones.</para>
     </sect2>
 
     <sect2>
       <title>Security</title>
 
       <para>Although BIND is the most common implementation of DNS,
         there is always the issue of security.  Possible and
         exploitable security holes are sometimes found.
       </para>
 
       <para>While &os; automatically drops
 	<application>named</application> into a &man.chroot.8;
 	environment; there are several other security mechanisms in
 	place which could help to lure off possible
 	<acronym>DNS</acronym> service attacks.</para>
 
       <para>It is always good idea to read <ulink
 	url="http://www.cert.org/">CERT</ulink>'s security advisories
 	and to subscribe to the &a.security-notifications; to stay up to
 	date with the current Internet and &os; security issues.</para>
 
       <tip>
 	<para>If a problem arises, keeping sources up to date and
 	  having a fresh build of <application>named</application> would
 	  not hurt.</para>
       </tip>
     </sect2>
 
     <sect2>
       <title>Further Reading</title>
 
       <para>BIND/<application>named</application> manual pages:
       &man.rndc.8; &man.named.8; &man.named.conf.5;</para>
 
       <itemizedlist>
 	<listitem>
 	  <para><ulink
 	      url="http://www.isc.org/products/BIND/">Official ISC BIND
 	      Page</ulink></para>
 	</listitem>
 
 	<listitem>
 	  <para><ulink
 	      url="http://www.isc.org/sw/guild/bf/">Official ISC BIND
 	      Forum</ulink></para>
 	</listitem>
 
 	<listitem>
 	  <para><ulink
 	      url="http://www.nominum.com/getOpenSourceResource.php?id=6">
 	      BIND FAQ</ulink></para>
 	</listitem>
 
 	<listitem>
 	  <para><ulink url="http://www.oreilly.com/catalog/dns5/">O'Reilly
 	      DNS and BIND 5th Edition</ulink></para>
 	</listitem>
 
 	<listitem>
 	  <para><ulink
 	      url="ftp://ftp.isi.edu/in-notes/rfc1034.txt">RFC1034
 	      - Domain Names - Concepts and Facilities</ulink></para>
 	</listitem>
 
 	<listitem>
 	  <para><ulink
 	      url="ftp://ftp.isi.edu/in-notes/rfc1035.txt">RFC1035
 	      - Domain Names - Implementation and Specification</ulink></para>
 	</listitem>
       </itemizedlist>
     </sect2>
   </sect1>
 
   <sect1 id="network-apache">
     <sect1info>
       <authorgroup>
 	<author>
 	  <firstname>Murray</firstname>
 	  <surname>Stokely</surname>
 	  <contrib>Contributed by </contrib>
 	</author>
       </authorgroup>
     </sect1info>
     <title>Apache HTTP Server</title>
 
     <indexterm><primary>web servers</primary>
       <secondary>setting up</secondary></indexterm>
     <indexterm><primary>Apache</primary></indexterm>
 
     <sect2>
       <title>Overview</title>
 
       <para>&os; is used to run some of the busiest web sites in the
         world.  The majority of web servers on the Internet are using
         the <application>Apache HTTP Server</application>.
         <application>Apache</application> software packages should be
         included on your FreeBSD installation media.  If you did not
         install <application>Apache</application> when you first
         installed FreeBSD, then you can install it from the <filename
         role="package">www/apache13</filename> or <filename
         role="package">www/apache20</filename> port.</para>
 
       <para>Once <application>Apache</application> has been installed
         successfully, it must be configured.</para>
 
       <note><para>This section covers version 1.3.X of the
         <application>Apache HTTP Server</application> as that is the
         most widely used version for &os;.  <application>Apache</application>&nbsp;2.X introduces many
         new technologies but they are not discussed here.  For more
         information about <application>Apache</application>&nbsp;2.X, please see <ulink
         url="http://httpd.apache.org/"></ulink>.</para></note>
 
     </sect2>
 
     <sect2>
       <title>Configuration</title>
 
       <indexterm><primary>Apache</primary>
 	<secondary>configuration file</secondary></indexterm>
 
       <para>The main <application>Apache HTTP Server</application> configuration file is
 	installed as
 	<filename>/usr/local/etc/apache/httpd.conf</filename> on &os;.
 	This file is a typical &unix; text configuration file with
 	comment lines beginning with the <literal>#</literal>
 	character.  A comprehensive description of all possible
 	configuration options is outside the scope of this book, so
 	only the most frequently modified directives will be described
 	here.</para>
 
       <variablelist>
 	<varlistentry>
 	  <term><literal>ServerRoot "/usr/local"</literal></term>
 
 	  <listitem>
 	    <para>This specifies the default directory hierarchy for
 	    the <application>Apache</application> installation.  Binaries are stored in the
 	    <filename class="directory">bin</filename> and 
 	    <filename class="directory">sbin</filename> subdirectories
 	    of the server root, and configuration files are stored in
 	    <filename class="directory">etc/apache</filename>.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term><literal>ServerAdmin you@your.address</literal></term>
 
 	  <listitem>
 	    <para>The address to which problems with the server should
 	      be emailed.  This address appears on some
 	      server-generated pages, such as error documents.</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term><literal>ServerName www.example.com</literal></term>
 
 	  <listitem>
 	    <para><literal>ServerName</literal> allows you to set a host name which is
 	      sent back to clients for your server if it is different
 	      to the one that the host is configured with (i.e., use <hostid>www</hostid>
 	      instead of the host's real name).</para>
 	  </listitem>
 	</varlistentry>
 
 	<varlistentry>
 	  <term><literal>DocumentRoot "/usr/local/www/data"</literal></term>
 
 	  <listitem>
 	    <para><literal>DocumentRoot</literal>: The directory out of which you will
 	      serve your documents. By default, all requests are taken
 	      from this directory, but symbolic links and aliases may
 	      be used to point to other locations.</para>
 	  </listitem>
 	</varlistentry>
       </variablelist>
 
       <para>It is always a good idea to make backup copies of your
 	<application>Apache</application> configuration file before making changes.  Once you are
 	satisfied with your initial configuration you are ready to
 	start running <application>Apache</application>.</para>
 
 <!-- sect3 for performance tuning directives?  maxservers minservers -->
 <!-- etc..?? -->
 
 <!-- Advanced configuration section.
 
 Performance tuning directives.
 
 Log file format -->
 
     </sect2>
 
     <sect2>
       <title>Running <application>Apache</application></title>
 
       <indexterm><primary>Apache</primary>
 	<secondary>starting or stopping</secondary></indexterm>
 
       <para><application>Apache</application> does not run from the
         <application>inetd</application> super server as many other
         network servers do.  It is configured to run standalone for
         better performance for incoming HTTP requests from client web
         browsers.  A shell script wrapper is included to make
         starting, stopping, and restarting the server as simple as
         possible.  To start up <application>Apache</application> for
         the first time, just run:</para>
 
       <screen>&prompt.root; <userinput>/usr/local/sbin/apachectl start</userinput></screen>
 
       <para>You can stop the server at any time by typing:</para>
 
       <screen>&prompt.root; <userinput>/usr/local/sbin/apachectl stop</userinput></screen>
 
       <para>After making changes to the configuration file for any
       reason, you will need to restart the server:</para>
 
       <screen>&prompt.root; <userinput>/usr/local/sbin/apachectl restart</userinput></screen>
 
       <para>To restart <application>Apache</application> without
 	aborting current connections, run:</para>
 
       <screen>&prompt.root; <userinput>/usr/local/sbin/apachectl graceful</userinput></screen>
 
       <para>Additional information available at
 	&man.apachectl.8; manual page.</para>
 
       <para>To launch <application>Apache</application> at system
         startup, add the following line to
         <filename>/etc/rc.conf</filename>:</para>
 
       <programlisting>apache_enable="YES"</programlisting>
 
       <para>If you would like to supply additional command line
 	options for the <application>Apache</application>
 	<command>httpd</command> program started at system boot, you
 	may specify them with an additional line in
 	<filename>rc.conf</filename>:</para>
 
       <programlisting>apache_flags=""</programlisting>
 
       <para>Now that the web server is running, you can view your web
         site by pointing a web browser to
         <literal>http://localhost/</literal>.  The default web page
         that is displayed is
         <filename>/usr/local/www/data/index.html</filename>.</para>
 
     </sect2>
 
     <sect2>
       <title>Virtual Hosting</title>
 
       <para><application>Apache</application> supports two different
 	types of Virtual Hosting. The first method is Name-based
 	Virtual Hosting. Name-based virtual hosting uses the clients
 	HTTP/1.1 headers to figure out the hostname. This allows many
 	different domains to share the same IP address.</para>
 
       <para>To setup <application>Apache</application> to use
         Name-based Virtual Hosting add an entry like the following to
         your <filename>httpd.conf</filename>:</para>
 
       <programlisting>NameVirtualHost *</programlisting>
 
       <para>If your webserver was named <hostid role="fqdn">www.domain.tld</hostid> and
         you wanted to setup a virtual domain for
         <hostid role="fqdn">www.someotherdomain.tld</hostid> then you would add
         the following entries to
         <filename>httpd.conf</filename>:</para>
 
       <screen>&lt;VirtualHost *&gt;
 ServerName www.domain.tld
 DocumentRoot /www/domain.tld
 &lt;/VirtualHost&gt;
 
 &lt;VirtualHost *&gt;
 ServerName www.someotherdomain.tld
 DocumentRoot /www/someotherdomain.tld
 &lt;/VirtualHost&gt;</screen>
 
       <para>Replace the addresses with the addresses you want to use
         and the path to the documents with what you are using.</para>
 
       <para>For more information about setting up virtual hosts,
         please consult the official <application>Apache</application>
         documentation at: <ulink
         url="http://httpd.apache.org/docs/vhosts/"></ulink>.</para>
 
     </sect2>
 
     <sect2>
       <title>Apache Modules</title>
 
       <indexterm><primary>Apache</primary>
 	<secondary>modules</secondary></indexterm>
 
       <para>There are many different <application>Apache</application> modules available to add
         functionality to the basic server.  The FreeBSD Ports
         Collection provides an easy way to install
         <application>Apache</application> together with some of the
         more popular add-on modules.</para>
 
       <sect3>
         <title>mod_ssl</title>
 
 	<indexterm><primary>web servers</primary>
           <secondary>secure</secondary></indexterm>
 	<indexterm><primary>SSL</primary></indexterm>
 	<indexterm><primary>cryptography</primary></indexterm>
 
         <para>The <application>mod_ssl</application> module uses the OpenSSL library to provide
           strong cryptography via the Secure Sockets Layer (SSL v2/v3)
           and Transport Layer Security (TLS v1) protocols.  This
           module provides everything necessary to request a signed
           certificate from a trusted certificate signing authority so
           that you can run a secure web server on &os;.</para>
 
 	<para>If you have not yet installed
 	  <application>Apache</application>, then a version of <application>Apache</application>
 	  1.3.X that includes <application>mod_ssl</application> may be installed with the <filename
 	  role="package">www/apache13-modssl</filename> port.  SSL
 	  support is also available for <application>Apache</application>&nbsp;2.X in the
 	  <filename role="package">www/apache20</filename> port,
 	  where it is enabled by default.</para>
 
 <!-- XXX add more information about configuring mod_ssl here. -->
 <!-- Generating keys, getting the key signed, setting up your secure -->
 <!-- web server! -->
       </sect3>
 
       <sect3>
         <title>Dynamic Websites with Perl &amp; PHP</title>
         <para>In the past few years, more businesses have turned to the
           Internet in order to enhance their revenue and increase
           exposure.  This has also increased the need for interactive
           web content.  While some companies, such as &microsoft;, have
           introduced solutions into their proprietary products, the
           open source community answered the call.  Two options for
           dynamic web content include
           <application>mod_perl</application> &amp;
           <application>mod_php</application>.</para>
 
         <sect4>
         <title>mod_perl</title>
 
 	<indexterm>
           <primary>mod_perl</primary>
           <secondary>Perl</secondary>
         </indexterm>
 
         <para>The <application>Apache</application>/Perl integration project brings together the
 	  full power of the Perl programming language and the <application>Apache
 	  HTTP Server</application>.  With the <application>mod_perl</application> module it is possible to
 	  write <application>Apache</application> modules entirely in Perl.  In addition, the
 	  persistent interpreter embedded in the server avoids the
 	  overhead of starting an external interpreter and the penalty
 	  of Perl start-up time.</para>
 
           <para><application>mod_perl</application> is available a few
             different ways.  To use <application>mod_perl</application>
             remember that <application>mod_perl</application> 1.0 only
             works with <application>Apache</application> 1.3 and
             <application>mod_perl</application> 2.0 only works with
             <application>Apache</application> 2.
             <application>mod_perl</application> 1.0 is available in
             <filename role="package">www/mod_perl</filename> and a
             statically compiled version is available in
             <filename role="package">www/apache13-modperl</filename>.
             <application>mod_perl</application> 2.0 is avaliable in
             <filename role="package">www/mod_perl2</filename>.</para>
         </sect4>
 
         <sect4>
           <sect4info>
 	  <authorgroup>
 	    <author>
 	      <firstname>Tom</firstname>
 	      <surname>Rhodes</surname>
 	      <contrib>Written by </contrib>
 	    </author>
 	  </authorgroup>
         </sect4info>
         <title>mod_php</title>
 
 	<indexterm>
           <primary>mod_php</primary>
           <secondary>PHP</secondary>
         </indexterm>
 
 	<para><acronym>PHP</acronym>, also known as <quote>PHP:
           Hypertext Preprocessor</quote> is a general-purpose scripting
           language that is especially suited for Web development.
           Capable of being embedded into <acronym>HTML</acronym> its
           syntax draws upon C, &java;, and Perl with the intention of
           allowing web developers to write dynamically generated
           webpages quickly.</para>
 
 	<para>To gain support for <acronym>PHP</acronym>5 for the
 	  <application>Apache</application> web server, begin by
 	  installing the
 	  <filename role="package">lang/php5</filename>
 	  port.</para>
 
 	<para>If the <filename role="package">lang/php5</filename> port
 	  is being installed for the first time, available
 	  <literal>OPTIONS</literal> will be displayed automatically.
 	  If a menu is not displayed, i.e. because the <filename
 	  role="package">lang/php5</filename> port has been installed
 	  some time in the past, it is always possible to bring the
 	  options dialog up again by running:</para>
 
 	<screen>&prompt.root; <userinput>make config</userinput></screen>
 
 	<para>in the port directory.</para>
 
 	<para>In the options dialog, check the
 	  <literal>APACHE</literal> option to build
 	  <application>mod_php5</application> as a loadable module for
 	  the <application>Apache</application> web server.</para>
 
 	<note>
 	  <para>A lot of sites are still using <acronym>PHP</acronym>4
 	    for various reasons (i.e. compatibility issues or already
 	    deployed web applications).  If the
 	    <application>mod_php4</application> is needed instead of
 	    <application>mod_php5</application>, then please use the
 	    <filename role="package">lang/php4</filename> port.  The
 	    <filename role="package">lang/php4</filename> port supports
 	    many of the configuration and build-time options of the
 	    <filename role="package">lang/php5</filename> port.</para>
 	</note>
 
 	<para>This will install and configure the modules required
           to support dynamic <acronym>PHP</acronym> applications.  Check
           to ensure the following sections have been added to
 	  <filename>/usr/local/etc/apache/httpd.conf</filename>:</para>
 
 	<programlisting>LoadModule php5_module        libexec/apache/libphp5.so</programlisting>
 
         <programlisting>AddModule mod_php5.c
     &lt;IfModule mod_php5.c&gt;
         DirectoryIndex index.php index.html
     &lt;/IfModule&gt;
     &lt;IfModule mod_php5.c&gt;
         AddType application/x-httpd-php .php
         AddType application/x-httpd-php-source .phps
     &lt;/IfModule&gt;</programlisting>
 
           <para>Once completed, a simple call to the
             <command>apachectl</command> command for a graceful
             restart is needed to load the <acronym>PHP</acronym>
             module:</para>
 
 	<screen>&prompt.root; <userinput>apachectl graceful</userinput></screen>
 
 	<para>For future upgrades of <acronym>PHP</acronym>, the
 	  <command>make config</command> command will not be required;
 	  the selected <literal>OPTIONS</literal> are saved
 	  automatically by the &os; Ports framework.</para>
 
           <para>The <acronym>PHP</acronym> support in &os; is extremely
             modular so the base install is very limited.  It is very easy
             to add support using the
             <filename role="package">lang/php5-extensions</filename> port.
             This port provides a menu driven interface to
             <acronym>PHP</acronym> extension installation.
             Alternatively, individual extensions can be installed using
             the appropriate port.</para>
 
 	<para>For instance, to add support for the
 	  <application>MySQL</application> database server to
 	  <acronym>PHP</acronym>5, simply install the
 	  <filename role="package">databases/php5-mysql</filename>
 	  port.</para>
 
           <para>After installing an extension, the
             <application>Apache</application> server must be reloaded to
               pick up the new configuration changes:</para>
 
 	<screen>&prompt.root; <userinput>apachectl graceful</userinput></screen>
         </sect4>
       </sect3>
     </sect2>
   </sect1>
 
   <sect1 id="network-ftp">
     <sect1info>
       <authorgroup>
 	<author>
 	  <firstname>Murray</firstname>
 	  <surname>Stokely</surname>
 	  <contrib>Contributed by </contrib>
 	</author>
       </authorgroup>
     </sect1info>
     <title>File Transfer Protocol (FTP)</title>
 
     <indexterm><primary>FTP servers</primary></indexterm>
 
     <sect2>
       <title>Overview</title>
 
       <para>The File Transfer Protocol (FTP) provides users with a
 	simple way to transfer files to and from an <acronym
 	role="File Transfer Protocol">FTP</acronym> server.  &os;
 	includes <acronym role="File Transfer Protocol">FTP</acronym>
 	server software, <application>ftpd</application>, in the base
 	system.  This makes setting up and administering an <acronym
 	role="File Transfer Protocol">FTP</acronym> server on FreeBSD
 	very straightforward.</para>
     </sect2>
 
     <sect2>
       <title>Configuration</title>
 
       <para>The most important configuration step is deciding which
 	accounts will be allowed access to the FTP server.  A normal
 	FreeBSD system has a number of system accounts used for
 	various daemons, but unknown users should not be allowed to
 	log in with these accounts.  The
 	<filename>/etc/ftpusers</filename> file is a list of users
 	disallowed any FTP access.  By default, it includes the
 	aforementioned system accounts, but it is possible to add
 	specific users here that should not be allowed access to
 	FTP.</para>
 
       <para>You may want to restrict the access of some users without
 	preventing them completely from using FTP.  This can be
 	accomplished with the <filename>/etc/ftpchroot</filename>
 	file.  This file lists users and groups subject to FTP access
 	restrictions.  The &man.ftpchroot.5; manual page has all of
 	the details so it will not be described in detail here.</para>
 
       <indexterm>
 	<primary>FTP</primary>
 	<secondary>anonymous</secondary>
       </indexterm>
 
       <para>If you would like to enable anonymous FTP access to your
 	server, then you must create a user named
 	<username>ftp</username> on your &os; system.  Users will then
 	be able to log on to your FTP server with a username of
 	<username>ftp</username> or <username>anonymous</username> and
 	with any password (by convention an email address for the user
 	should be used as the password).  The FTP server will call
 	&man.chroot.2; when an anonymous user logs in, to restrict
 	access to only the home directory of the
 	<username>ftp</username> user.</para>
 
       <para>There are two text files that specify welcome messages to
 	be displayed to FTP clients.  The contents of the file
 	<filename>/etc/ftpwelcome</filename> will be displayed to
 	users before they reach the login prompt.  After a successful
 	login, the contents of the file
 	<filename>/etc/ftpmotd</filename> will be displayed.  Note
 	that the path to this file is relative to the login environment, so the
 	file <filename>~ftp/etc/ftpmotd</filename> would be displayed
 	for anonymous users.</para>
 
       <para>Once the FTP server has been configured properly, it must
         be enabled in <filename>/etc/inetd.conf</filename>.  All that
         is required here is to remove the comment symbol
         <quote>#</quote> from in front of the existing
         <application>ftpd</application> line :</para>
 
       <programlisting>ftp	stream	tcp	nowait	root	/usr/libexec/ftpd	ftpd -l</programlisting>
 
       <para>As explained in <xref linkend="network-inetd-reread">,
         the <application>inetd</application> configuration must be reloaded
         after this configuration file is changed.</para>
 
       <para>You can now log on to your FTP server by typing:</para>
 
       <screen>&prompt.user; <userinput>ftp localhost</userinput></screen>
 
     </sect2>
 
     <sect2>
       <title>Maintaining</title>
 
       <indexterm><primary>syslog</primary></indexterm>
       <indexterm><primary>log files</primary>
 	<secondary>FTP</secondary></indexterm>
 
       <para>The <application>ftpd</application> daemon uses
         &man.syslog.3; to log messages.  By default, the system log
         daemon will put messages related to FTP in the
         <filename>/var/log/xferlog</filename> file.  The location of
         the FTP log can be modified by changing the following line in
         <filename>/etc/syslog.conf</filename>:</para>
 
       <programlisting>ftp.info      /var/log/xferlog</programlisting>
 
       <indexterm>
 	<primary>FTP</primary>
 	<secondary>anonymous</secondary>
       </indexterm>
 
       <para>Be aware of the potential problems involved with running
         an anonymous FTP server.  In particular, you should think
         twice about allowing anonymous users to upload files.  You may
         find that your FTP site becomes a forum for the trade of
         unlicensed commercial software or worse.  If you do need to
         allow anonymous FTP uploads, then you should set up the
         permissions so that these files can not be read by other
         anonymous users until they have been reviewed.</para>
 
     </sect2>
   </sect1>
 
   <sect1 id="network-samba">
     <sect1info>
       <authorgroup>
 	<author>
 	  <firstname>Murray</firstname>
 	  <surname>Stokely</surname>
 	  <contrib>Contributed by </contrib>
 	</author>
       </authorgroup>
     </sect1info>
     <title>File and Print Services for &microsoft.windows; clients (Samba)</title>
 
     <indexterm><primary>Samba server</primary></indexterm>
     <indexterm><primary>Microsoft Windows</primary></indexterm>
     <indexterm>
       <primary>file server</primary>
       <secondary>Windows clients</secondary>
     </indexterm>
     <indexterm>
       <primary>print server</primary>
       <secondary>Windows clients</secondary>
     </indexterm>
 
     <sect2>
       <title>Overview</title>
 
       <para><application>Samba</application> is a popular open source
         software package that provides file and print services for
         &microsoft.windows; clients.  Such clients can connect to and
         use FreeBSD filespace as if it was a local disk drive, or
         FreeBSD printers as if they were local printers.</para>
 
       <para><application>Samba</application> software packages should
         be included on your FreeBSD installation media.  If you did
         not install <application>Samba</application> when you first
         installed FreeBSD, then you can install it from the <filename
         role="package">net/samba3</filename> port or package.</para>
 
 <!-- mention LDAP, Active Directory, WinBIND, ACL, Quotas, PAM, .. -->
 
     </sect2>
 
     <sect2>
       <title>Configuration</title>
 
       <para>A default <application>Samba</application> configuration
         file is installed as
         <filename>/usr/local/etc/smb.conf.default</filename>.  This
         file must be copied to
         <filename>/usr/local/etc/smb.conf</filename> and customized
         before <application>Samba</application> can be used.</para>
 
       <para>The <filename>smb.conf</filename> file contains runtime
         configuration information for
         <application>Samba</application>, such as definitions of the
         printers and <quote>file system shares</quote> that you would
         like to share with &windows; clients.  The
         <application>Samba</application> package includes a web based
         tool called <application>swat</application> which provides a
         simple way of configuring the <filename>smb.conf</filename>
         file.</para>
 
       <sect3>
 	<title>Using the Samba Web Administration Tool (SWAT)</title>
 
 	<para>The Samba Web Administration Tool (SWAT) runs as a
 	  daemon from <application>inetd</application>.  Therefore, the
 	  following line in <filename>/etc/inetd.conf</filename>
 	  should be uncommented before <application>swat</application> can be
 	  used to configure <application>Samba</application>:</para>
 
 	<programlisting>swat   stream  tcp     nowait/400      root    /usr/local/sbin/swat</programlisting>
         <para>As explained in <xref linkend="network-inetd-reread">,
           the <application>inetd</application> must be reloaded after this configuration
           file is changed.</para>
 
 	<para>Once <application>swat</application> has been enabled in
 	  <filename>inetd.conf</filename>, you can use a browser to
 	  connect to <ulink url="http://localhost:901"></ulink>.  You will
 	  first have to log on with the system <username>root</username> account.</para>
 
 <!-- XXX screenshots go here, loader is creating them -->
 
 	<para>Once you have successfully logged on to the main
 	  <application>Samba</application> configuration page, you can
 	  browse the system documentation, or begin by clicking on the
 	  <guimenu>Globals</guimenu> tab.  The <guimenu>Globals</guimenu> section corresponds to the
 	  variables that are set in the <literal>[global]</literal>
 	  section of
 	  <filename>/usr/local/etc/smb.conf</filename>.</para>
       </sect3>
 
       <sect3>
 	<title>Global Settings</title>
 
 	<para>Whether you are using <application>swat</application> or
 	  editing <filename>/usr/local/etc/smb.conf</filename>
 	  directly, the first directives you are likely to encounter
 	  when configuring <application>Samba</application>
 	  are:</para>
 
         <variablelist>
 	  <varlistentry>
 	    <term><literal>workgroup</literal></term>
 
 	    <listitem>
 	      <para>NT Domain-Name or Workgroup-Name for the computers
 	        that will be accessing this server.</para>
 	    </listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term><literal>netbios name</literal></term>
 	    <indexterm><primary>NetBIOS</primary></indexterm>
 
 	    <listitem>
 	      <para>This sets the NetBIOS name by which a <application>Samba</application> server
 		is known. By default it is the same as the first
 		component of the host's DNS name.</para>
 	    </listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term><literal>server string</literal></term>
 
 	    <listitem>
 	      <para>This sets the string that will be displayed with
 		the <command>net view</command> command and some other
 		networking tools that seek to display descriptive text
 		about the server.</para>
 	    </listitem>
 	  </varlistentry>
         </variablelist>
       </sect3>
 
       <sect3>
 	<title>Security Settings</title>
 
 	<para>Two of the most important settings in
 	  <filename>/usr/local/etc/smb.conf</filename> are the
 	  security model chosen, and the backend password format for
 	  client users.  The following directives control these
 	  options:</para>
 
         <variablelist>
 	  <varlistentry>
 	    <term><literal>security</literal></term>
 
 	    <listitem>
 	      <para>The two most common options here are
 	        <literal>security = share</literal> and <literal>security
 	        = user</literal>.  If your clients use usernames that
 	        are the same as their usernames on your &os; machine
 	        then you will want to use user level security.  This
 	        is the default security policy and it requires clients
 	        to first log on before they can access shared
 	        resources.</para>
 
 	      <para>In share level security, client do not need to log
 	        onto the server with a valid username and password
 	        before attempting to connect to a shared resource.
 	        This was the default security model for older versions
 	        of <application>Samba</application>.</para>
 	    </listitem>
 	  </varlistentry>
 
 	  <varlistentry>
 	    <term><literal>passdb backend</literal></term>
 
 	    <indexterm><primary>NIS+</primary></indexterm>
 	    <indexterm><primary>LDAP</primary></indexterm>
 	    <indexterm><primary>SQL database</primary></indexterm>
 
 	    <listitem>
 	      <para><application>Samba</application> has several
 	        different backend authentication models.  You can
 	        authenticate clients with LDAP, NIS+, a SQL database,
 	        or a modified password file.  The default
 	        authentication method is <literal>smbpasswd</literal>,
 	        and that is all that will be covered here.</para>
 	    </listitem>
 	  </varlistentry>
 	</variablelist>
 
 	<para>Assuming that the default <literal>smbpasswd</literal>
 	  backend is used, the
 	  <filename>/usr/local/private/smbpasswd</filename> file must
 	  be created to allow <application>Samba</application> to
 	  authenticate clients.  If you would like to give all of
 	  your &unix; user accounts access from &windows; clients, use the
 	  following command:</para>
 
 	<screen>&prompt.root; <userinput>grep -v "^#" /etc/passwd | make_smbpasswd &gt; /usr/local/private/smbpasswd</userinput>
 &prompt.root; <userinput>chmod 600 /usr/local/private/smbpasswd</userinput></screen>
 
 	<para>Please see the <application>Samba</application>
 	  documentation for additional information about configuration
 	  options.  With the basics outlined here, you should have
 	  everything you need to start running
 	  <application>Samba</application>.</para>
       </sect3>
 
     </sect2>
     <sect2>
       <title>Starting <application>Samba</application></title>
 
-      <para>To enable <application>Samba</application> when your
-        system boots, add the following line to
-        <filename>/etc/rc.conf</filename>:</para>
+      <para>The <filename role="package">net/samba3</filename> port adds
+	a new startup script, which can be used to control
+	<application>Samba</application>.  To enable this script, so
+	that it can be used for example to start, stop or restart
+	<application>Samba</application>, add the following line to the
+	<filename>/etc/rc.conf</filename> file:</para>
 
       <programlisting>samba_enable="YES"</programlisting>
 
-      <para>You can then start <application>Samba</application> at any
-        time by typing:</para>
+      <note>
+	<para>This will also configure <application>Samba</application>
+	  to automatically start at system boot time.</para>
+      </note>
+
+      <para>It is possible then to start
+	<application>Samba</application> at any time by typing:</para>
 
-      <screen>&prompt.root; <userinput>/usr/local/etc/rc.d/samba.sh start</userinput>
+      <screen>&prompt.root; <userinput>/usr/local/etc/rc.d/samba start</userinput>
 Starting SAMBA: removing stale tdbs :
 Starting nmbd.
 Starting smbd.</screen>
 
+      <para>Please refer to <xref linkend="configtuning-rcd"> for more
+	information about using rc scripts.</para>
+
       <para><application>Samba</application> actually consists of
         three separate daemons.  You should see that both the
         <application>nmbd</application> and <application>smbd</application> daemons
         are started by the <filename>samba.sh</filename> script.  If
         you enabled winbind name resolution services in
         <filename>smb.conf</filename>, then you will also see that
         the <application>winbindd</application> daemon is started.</para>
 
       <para>You can stop <application>Samba</application> at any time
         by typing :</para>
 
       <screen>&prompt.root; <userinput>/usr/local/etc/rc.d/samba.sh stop</userinput></screen>
 
       <para><application>Samba</application> is a complex software
         suite with functionality that allows broad integration with
         &microsoft.windows; networks.  For more information about
         functionality beyond the basic installation described here,
         please see <ulink url="http://www.samba.org"></ulink>.</para>
     </sect2>
 
   </sect1>
 
   <sect1 id="network-ntp">
     <sect1info>
       <authorgroup>
 	<author>
 	  <firstname>Tom</firstname>
 	  <surname>Hukins</surname>
 	  <contrib>Contributed by </contrib>
 	</author>
       </authorgroup>
     </sect1info>
     <title>Clock Synchronization with NTP</title>
 
     <indexterm><primary>NTP</primary></indexterm>
 
     <sect2>
       <title>Overview</title>
 
       <para>Over time, a computer's clock is prone to drift.  The
 	Network Time Protocol (NTP) is one way to ensure your clock stays
 	accurate.</para>
 
       <para>Many Internet services rely on, or greatly benefit from,
 	computers' clocks being accurate.  For example, a web server
 	may receive requests to send a file if it has been modified since a
 	certain time.  In a local area network environment, it is
 	essential that computers sharing files from the same file
 	server have synchronized clocks so that file timestamps stay
 	consistent.  Services such as &man.cron.8; also rely on
 	an accurate system clock to run commands at the specified
 	times.</para>
 
       <indexterm>
 	<primary>NTP</primary>
 	<secondary>ntpd</secondary>
       </indexterm>
       <para>FreeBSD ships with the &man.ntpd.8; <acronym role="Network
 	Time Protocol">NTP</acronym> server which can be used to query
 	other <acronym role="Network Time Protocol">NTP</acronym>
 	servers to set the clock on your machine or provide time
 	services to others.</para>
     </sect2>
 
     <sect2>
       <title>Choosing Appropriate NTP Servers</title>
 
       <indexterm>
 	<primary>NTP</primary>
 	<secondary>choosing servers</secondary>
       </indexterm>
 
       <para>In order to synchronize your clock, you will need to find
 	one or more <acronym role="Network Time
 	Protocol">NTP</acronym> servers to use.  Your network
 	administrator or ISP may have set up an NTP server for this
 	purpose&mdash;check their documentation to see if this is the
 	case.  There is an <ulink
 	url="http://ntp.isc.org/bin/view/Servers/WebHome">online
 	list of publicly accessible NTP servers</ulink> which you can
 	use to find an NTP server near to you.  Make sure you are
 	aware of the policy for any servers you choose, and ask for
 	permission if required.</para>
 
       <para>Choosing several unconnected NTP servers is a good idea in
 	case one of the servers you are using becomes unreachable or
 	its clock is unreliable.  &man.ntpd.8; uses the responses it
 	receives from other servers intelligently&mdash;it will favor
 	unreliable servers less than reliable ones.</para>
     </sect2>
 
     <sect2>
       <title>Configuring Your Machine</title>
 
       <indexterm>
 	<primary>NTP</primary>
 	<secondary>configuration</secondary>
       </indexterm>
 
       <sect3>
 	<title>Basic Configuration</title>
 	<indexterm><primary>ntpdate</primary></indexterm>
 
 	<para>If you only wish to synchronize your clock when the
 	  machine boots up, you can use &man.ntpdate.8;.  This may be
 	  appropriate for some desktop machines which are frequently
 	  rebooted and only require infrequent synchronization, but
 	  most machines should run &man.ntpd.8;.</para>
 
 	<para>Using &man.ntpdate.8; at boot time is also a good idea
 	  for machines that run &man.ntpd.8;.  The &man.ntpd.8;
 	  program changes the clock gradually, whereas &man.ntpdate.8;
 	  sets the clock, no matter how great the difference between a
 	  machine's current clock setting and the correct time.</para>
 
 	<para>To enable &man.ntpdate.8; at boot time, add
 	  <literal>ntpdate_enable="YES"</literal> to
 	  <filename>/etc/rc.conf</filename>.  You will also need to
 	  specify all servers you wish to synchronize with and any
 	  flags to be passed to &man.ntpdate.8; in
 	  <varname>ntpdate_flags</varname>.</para>
       </sect3>
 
       <sect3>
 	<indexterm>
 	  <primary>NTP</primary>
 	  <secondary>ntp.conf</secondary>
 	</indexterm>
 
 	<title>General Configuration</title>
 
 	<para>NTP is configured by the
 	  <filename>/etc/ntp.conf</filename> file in the format
 	  described in &man.ntp.conf.5;.  Here is a simple
 	  example:</para>
 
 	<programlisting>server ntplocal.example.com prefer
 server timeserver.example.org
 server ntp2a.example.net
 
 driftfile /var/db/ntp.drift</programlisting>
 
 	<para>The <literal>server</literal> option specifies which
 	  servers are to be used, with one server listed on each line.
 	  If a server is specified with the <literal>prefer</literal>
 	  argument, as with <hostid
 	  role="fqdn">ntplocal.example.com</hostid>, that server is
 	  preferred over other servers.  A response from a preferred
 	  server will be discarded if it differs significantly from
 	  other servers' responses, otherwise it will be used without
 	  any consideration to other responses.  The
 	  <literal>prefer</literal> argument is normally used for NTP
 	  servers that are known to be highly accurate, such as those
 	  with special time monitoring hardware.</para>
 
 	<para>The <literal>driftfile</literal> option specifies which
 	  file is used to store the system clock's frequency offset.
 	  The &man.ntpd.8; program uses this to automatically
 	  compensate for the clock's natural drift, allowing it to
 	  maintain a reasonably correct setting even if it is cut off
 	  from all external time sources for a period of time.</para>
 
 	<para>The <literal>driftfile</literal> option specifies which
 	  file is used to store information about previous responses
 	  from the NTP servers you are using.  This file contains
 	  internal information for NTP.  It should not be modified by
 	  any other process.</para>
       </sect3>
 
       <sect3>
 	<title>Controlling Access to Your Server</title>
 
 	<para>By default, your NTP server will be accessible to all
 	  hosts on the Internet.  The <literal>restrict</literal>
 	  option in <filename>/etc/ntp.conf</filename> allows you to
 	  control which machines can access your server.</para>
 
 	<para>If you want to deny all machines from accessing your NTP
 	  server, add the following line to
 	  <filename>/etc/ntp.conf</filename>:</para>
 
         <programlisting>restrict default ignore</programlisting>
 
         <para>If you only want to allow machines within your own
 	  network to synchronize their clocks with your server, but
 	  ensure they are not allowed to configure the server or used
 	  as peers to synchronize against, add</para>
 
         <programlisting>restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap</programlisting>
 
 	<para>instead, where <hostid role="ipaddr">192.168.1.0</hostid> is
 	  an IP address on your network and <hostid
 	  role="netmask">255.255.255.0</hostid> is your network's
 	  netmask.</para>
 
 	<para><filename>/etc/ntp.conf</filename> can contain multiple
 	  <literal>restrict</literal> options.  For more details, see
 	  the <literal>Access Control Support</literal> subsection of
 	  &man.ntp.conf.5;.</para>
       </sect3>
     </sect2>
 
     <sect2>
       <title>Running the NTP Server</title>
 
       <para>To ensure the NTP server is started at boot time, add the
 	line <literal>ntpd_enable="YES"</literal> to
 	<filename>/etc/rc.conf</filename>.  If you wish to pass
 	additional flags to &man.ntpd.8;, edit the
 	<varname>ntpd_flags</varname> parameter in
 	<filename>/etc/rc.conf</filename>.</para>
 
       <para>To start the server without rebooting your machine, run
 	<command>ntpd</command> being sure to specify any additional
 	parameters from <varname>ntpd_flags</varname> in
 	<filename>/etc/rc.conf</filename>.  For example:</para>
 
       <screen>&prompt.root; <userinput>ntpd -p /var/run/ntpd.pid</userinput></screen>
     </sect2>
 
     <sect2>
       <title>Using ntpd with a Temporary Internet
 	Connection</title>
 
       <para>The &man.ntpd.8; program does not need a permanent
 	connection to the Internet to function properly.  However, if
 	you have a temporary connection that is configured to dial out
 	on demand, it is a good idea to prevent NTP traffic from
 	triggering a dial out or keeping the connection alive.  If you
 	are using user PPP, you can use <literal>filter</literal>
 	directives in <filename>/etc/ppp/ppp.conf</filename>.  For
 	example:</para>
 
       <programlisting> set filter dial 0 deny udp src eq 123
  # Prevent NTP traffic from initiating dial out
  set filter dial 1 permit 0 0
  set filter alive 0 deny udp src eq 123
  # Prevent incoming NTP traffic from keeping the connection open
  set filter alive 1 deny udp dst eq 123
  # Prevent outgoing NTP traffic from keeping the connection open
  set filter alive 2 permit 0/0 0/0</programlisting>
 
       <para>For more details see the <literal>PACKET
 	FILTERING</literal> section in &man.ppp.8; and the examples in
 	<filename>/usr/share/examples/ppp/</filename>.</para>
 
       <note>
 	<para>Some Internet access providers block low-numbered ports,
 	  preventing NTP from functioning since replies never
 	  reach your machine.</para>
       </note>
     </sect2>
 
     <sect2>
       <title>Further Information</title>
 
       <para>Documentation for the NTP server can be found in
 	<filename>/usr/share/doc/ntp/</filename> in HTML
 	format.</para>
     </sect2>
   </sect1>
 
 </chapter>
 
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