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<refentry>
  <refentryinfo>
    <date>June 30, 2000</date>
  </refentryinfo>

  <refmeta>
    <refentrytitle><application>lwresd</application></refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo>BIND9</refmiscinfo>
  </refmeta>

  <refnamediv>
    <refname><application>lwresd</application></refname>
    <refpurpose>lightweight resolver daemon</refpurpose>
  </refnamediv>

  <docinfo>
    <copyright>
      <year>2004</year>
      <year>2005</year>
      <year>2007</year>
      <year>2008</year>
      <year>2009</year>
      <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
    </copyright>
    <copyright>
      <year>2000</year>
      <year>2001</year>
      <holder>Internet Software Consortium.</holder>
    </copyright>
  </docinfo>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>lwresd</command>
      <arg><option>-c <replaceable class="parameter">config-file</replaceable></option></arg>
      <arg><option>-C <replaceable class="parameter">config-file</replaceable></option></arg>
      <arg><option>-d <replaceable class="parameter">debug-level</replaceable></option></arg>
      <arg><option>-f</option></arg>
      <arg><option>-g</option></arg>
      <arg><option>-i <replaceable class="parameter">pid-file</replaceable></option></arg>
      <arg><option>-m <replaceable class="parameter">flag</replaceable></option></arg>
      <arg><option>-n <replaceable class="parameter">#cpus</replaceable></option></arg>
      <arg><option>-P <replaceable class="parameter">port</replaceable></option></arg>
      <arg><option>-p <replaceable class="parameter">port</replaceable></option></arg>
      <arg><option>-s</option></arg>
      <arg><option>-t <replaceable class="parameter">directory</replaceable></option></arg>
      <arg><option>-u <replaceable class="parameter">user</replaceable></option></arg>
      <arg><option>-v</option></arg>
      <arg><option>-4</option></arg>
      <arg><option>-6</option></arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>DESCRIPTION</title>

    <para><command>lwresd</command>
      is the daemon providing name lookup
      services to clients that use the BIND 9 lightweight resolver
      library.  It is essentially a stripped-down, caching-only name
      server that answers queries using the BIND 9 lightweight
      resolver protocol rather than the DNS protocol.
    </para>

    <para><command>lwresd</command> 
      listens for resolver queries on a
      UDP port on the IPv4 loopback interface, 127.0.0.1.  This
      means that <command>lwresd</command> can only be used by
      processes running on the local machine.  By default, UDP port
      number 921 is used for lightweight resolver requests and
      responses.
    </para>
    <para>
      Incoming lightweight resolver requests are decoded by the
      server which then resolves them using the DNS protocol.  When
      the DNS lookup completes, <command>lwresd</command> encodes
      the answers in the lightweight resolver format and returns
      them to the client that made the request.
    </para>
    <para>
      If <filename>/etc/resolv.conf</filename> contains any
      <option>nameserver</option> entries, <command>lwresd</command>
      sends recursive DNS queries to those servers.  This is similar
      to the use of forwarders in a caching name server.  If no
      <option>nameserver</option> entries are present, or if
      forwarding fails, <command>lwresd</command> resolves the
      queries autonomously starting at the root name servers, using
      a built-in list of root server hints.
    </para>
  </refsect1>

  <refsect1>
    <title>OPTIONS</title>

    <variablelist>

      <varlistentry>
        <term>-4</term>
        <listitem>
          <para>
            Use IPv4 only even if the host machine is capable of IPv6.
            <option>-4</option> and <option>-6</option> are mutually
            exclusive.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-6</term>
        <listitem>
          <para>
            Use IPv6 only even if the host machine is capable of IPv4.
            <option>-4</option> and <option>-6</option> are mutually
            exclusive.
          </para>
        </listitem>
      </varlistentry>

      <!-- this is in source but not mentioned? does this matter? -->
      <varlistentry>
        <term>-c <replaceable class="parameter">config-file</replaceable></term>
        <listitem>
          <para>
            Use <replaceable class="parameter">config-file</replaceable> as the
            configuration file instead of the default,
            <filename>/etc/lwresd.conf</filename>.
	    <!-- Should this be an absolute path name? -->
	    <option>-c</option> can not be used with <option>-C</option>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-C <replaceable class="parameter">config-file</replaceable></term>
        <listitem>
          <para>
            Use <replaceable class="parameter">config-file</replaceable> as the
            configuration file instead of the default,
            <filename>/etc/resolv.conf</filename>.
	    <option>-C</option> can not be used with <option>-c</option>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-d <replaceable class="parameter">debug-level</replaceable></term>
        <listitem>
          <para>
            Set the daemon's debug level to <replaceable class="parameter">debug-level</replaceable>.
            Debugging traces from <command>lwresd</command> become
            		more verbose as the debug level increases.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-f</term>
        <listitem>
          <para>
            Run the server in the foreground (i.e. do not daemonize).
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-g</term>
        <listitem>
          <para>
            Run the server in the foreground and force all logging
            to <filename>stderr</filename>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-i <replaceable class="parameter">pid-file</replaceable></term>
        <listitem>
          <para>
            Use <replaceable class="parameter">pid-file</replaceable> as the
            PID file instead of the default,
            <filename>/var/run/lwresd.pid</filename>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-m <replaceable class="parameter">flag</replaceable></term>
        <listitem>
          <para>
            Turn on memory usage debugging flags.  Possible flags are
            <replaceable class="parameter">usage</replaceable>,
            <replaceable class="parameter">trace</replaceable>,
            <replaceable class="parameter">record</replaceable>,
            <replaceable class="parameter">size</replaceable>, and
            <replaceable class="parameter">mctx</replaceable>.  
            These correspond to the ISC_MEM_DEBUGXXXX flags described in
            <filename>&lt;isc/mem.h&gt;</filename>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-n <replaceable class="parameter">#cpus</replaceable></term>
        <listitem>
          <para>
            Create <replaceable class="parameter">#cpus</replaceable> worker threads
            to take advantage of multiple CPUs.  If not specified,
            <command>lwresd</command> will try to determine the
            number of CPUs present and create one thread per CPU.
            If it is unable to determine the number of CPUs, a
            single worker thread will be created.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-P <replaceable class="parameter">port</replaceable></term>
        <listitem>
          <para>
            Listen for lightweight resolver queries on port
            <replaceable class="parameter">port</replaceable>.  If
            		not specified, the default is port 921.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-p <replaceable class="parameter">port</replaceable></term>
        <listitem>
          <para>
            Send DNS lookups to port <replaceable class="parameter">port</replaceable>.  If not
            specified, the default is port 53.  This provides a
            way of testing the lightweight resolver daemon with a
            name server that listens for queries on a non-standard
            port number.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-s</term>
        <listitem>
          <para>
            Write memory usage statistics to <filename>stdout</filename>
            on exit.
          </para>
          <note>
            <para>
              This option is mainly of interest to BIND 9 developers
              and may be removed or changed in a future release.
            </para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-t <replaceable class="parameter">directory</replaceable></term>
        <listitem>
          <para>Chroot
	    to <replaceable class="parameter">directory</replaceable> after
            processing the command line arguments, but before
            reading the configuration file.
          </para>
          <warning>
            <para>
              This option should be used in conjunction with the
              <option>-u</option> option, as chrooting a process
              running as root doesn't enhance security on most
              systems; the way <function>chroot(2)</function> is
              defined allows a process with root privileges to
              escape a chroot jail.
            </para>
          </warning>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-u <replaceable class="parameter">user</replaceable></term>
        <listitem>
          <para>Setuid
	    to <replaceable class="parameter">user</replaceable> after completing
            privileged operations, such as creating sockets that
            listen on privileged ports.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-v</term>
        <listitem>
          <para>
            Report the version number and exit.
          </para>
        </listitem>
      </varlistentry>

    </variablelist>

  </refsect1>

  <refsect1>
    <title>FILES</title>

    <variablelist>

      <varlistentry>
        <term><filename>/etc/resolv.conf</filename></term>
        <listitem>
          <para>
            The default configuration file.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><filename>/var/run/lwresd.pid</filename></term>
        <listitem>
          <para>
            The default process-id file.
          </para>
        </listitem>
      </varlistentry>

    </variablelist>

  </refsect1>

  <refsect1>
    <title>SEE ALSO</title>
    <para><citerefentry>
        <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>lwres</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>resolver</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>.
    </para>
  </refsect1>

  <refsect1>
    <title>AUTHOR</title>
    <para><corpauthor>Internet Systems Consortium</corpauthor>
    </para>
  </refsect1>

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