<!-- - Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC") - Copyright (C) 2000, 2001 Internet Software Consortium. - - Permission to use, copy, modify, and distribute this software for any - purpose with or without fee is hereby granted, provided that the above - copyright notice and this permission notice appear in all copies. - - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR - PERFORMANCE OF THIS SOFTWARE. --> <!-- $Id: lwresd.html,v 1.4.2.1.4.10 2006/06/29 13:02:30 marka Exp $ --> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>lwresd</title> <meta name="generator" content="DocBook XSL Stylesheets V1.70.1"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en"> <a name="id2482688"></a><div class="titlepage"></div> <div class="refnamediv"> <h2>Name</h2> <p><span class="application">lwresd</span> — lightweight resolver daemon</p> </div> <div class="refsynopsisdiv"> <h2>Synopsis</h2> <div class="cmdsynopsis"><p><code class="command">lwresd</code> [<code class="option">-C <em class="replaceable"><code>config-file</code></em></code>] [<code class="option">-d <em class="replaceable"><code>debug-level</code></em></code>] [<code class="option">-f</code>] [<code class="option">-g</code>] [<code class="option">-i <em class="replaceable"><code>pid-file</code></em></code>] [<code class="option">-n <em class="replaceable"><code>#cpus</code></em></code>] [<code class="option">-P <em class="replaceable"><code>port</code></em></code>] [<code class="option">-p <em class="replaceable"><code>port</code></em></code>] [<code class="option">-s</code>] [<code class="option">-t <em class="replaceable"><code>directory</code></em></code>] [<code class="option">-u <em class="replaceable"><code>user</code></em></code>] [<code class="option">-v</code>]</p></div> </div> <div class="refsect1" lang="en"> <a name="id2549484"></a><h2>DESCRIPTION</h2> <p> <span><strong class="command">lwresd</strong></span> 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. </p> <p> <span><strong class="command">lwresd</strong></span> listens for resolver queries on a UDP port on the IPv4 loopback interface, 127.0.0.1. This means that <span><strong class="command">lwresd</strong></span> 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. </p> <p> Incoming lightweight resolver requests are decoded by the server which then resolves them using the DNS protocol. When the DNS lookup completes, <span><strong class="command">lwresd</strong></span> encodes the answers in the lightweight resolver format and returns them to the client that made the request. </p> <p> If <code class="filename">/etc/resolv.conf</code> contains any <code class="option">nameserver</code> entries, <span><strong class="command">lwresd</strong></span> sends recursive DNS queries to those servers. This is similar to the use of forwarders in a caching name server. If no <code class="option">nameserver</code> entries are present, or if forwarding fails, <span><strong class="command">lwresd</strong></span> resolves the queries autonomously starting at the root name servers, using a built-in list of root server hints. </p> </div> <div class="refsect1" lang="en"> <a name="id2549533"></a><h2>OPTIONS</h2> <div class="variablelist"><dl> <dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt> <dd><p> Use <em class="replaceable"><code>config-file</code></em> as the configuration file instead of the default, <code class="filename">/etc/resolv.conf</code>. </p></dd> <dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt> <dd><p> Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>. Debugging traces from <span><strong class="command">lwresd</strong></span> become more verbose as the debug level increases. </p></dd> <dt><span class="term">-f</span></dt> <dd><p> Run the server in the foreground (i.e. do not daemonize). </p></dd> <dt><span class="term">-g</span></dt> <dd><p> Run the server in the foreground and force all logging to <code class="filename">stderr</code>. </p></dd> <dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt> <dd><p> Create <em class="replaceable"><code>#cpus</code></em> worker threads to take advantage of multiple CPUs. If not specified, <span><strong class="command">lwresd</strong></span> 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. </p></dd> <dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt> <dd><p> Listen for lightweight resolver queries on port <em class="replaceable"><code>port</code></em>. If not specified, the default is port 921. </p></dd> <dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt> <dd><p> Send DNS lookups to port <em class="replaceable"><code>port</code></em>. 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. </p></dd> <dt><span class="term">-s</span></dt> <dd> <p> Write memory usage statistics to <code class="filename">stdout</code> on exit. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> This option is mainly of interest to BIND 9 developers and may be removed or changed in a future release. </p> </div> </dd> <dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt> <dd> <p> <code class="function">chroot()</code> to <em class="replaceable"><code>directory</code></em> after processing the command line arguments, but before reading the configuration file. </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Warning</h3> <p> This option should be used in conjunction with the <code class="option">-u</code> option, as chrooting a process running as root doesn't enhance security on most systems; the way <code class="function">chroot()</code> is defined allows a process with root privileges to escape a chroot jail. </p> </div> </dd> <dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt> <dd><p> <code class="function">setuid()</code> to <em class="replaceable"><code>user</code></em> after completing privileged operations, such as creating sockets that listen on privileged ports. </p></dd> <dt><span class="term">-v</span></dt> <dd><p> Report the version number and exit. </p></dd> </dl></div> </div> <div class="refsect1" lang="en"> <a name="id2549939"></a><h2>FILES</h2> <div class="variablelist"><dl> <dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt> <dd><p> The default configuration file. </p></dd> <dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt> <dd><p> The default process-id file. </p></dd> </dl></div> </div> <div class="refsect1" lang="en"> <a name="id2549978"></a><h2>SEE ALSO</h2> <p> <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>, <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>, <span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>. </p> </div> <div class="refsect1" lang="en"> <a name="id2550017"></a><h2>AUTHOR</h2> <p> <span class="corpauthor">Internet Systems Consortium</span> </p> </div> </div></body> </html>