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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>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>lwresd</command>
      <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>-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>
    </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>-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>.
          </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>-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>
		<function>chroot()</function> 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()</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>
		<function>setuid()</function> 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>

</refentry>


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