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e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<title>lwresd</title>
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e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<a name="id2456836"></a><div class="titlepage"></div>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<div class="refnamediv">
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<h2>Name</h2>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<p><span class="application">lwresd</span> &#8212; lightweight resolver daemon</p>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi</div>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<div class="refsynopsisdiv">
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<h2>Synopsis</h2>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<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>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi</div>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<div class="refsect1" lang="en">
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<a name="id2514261"></a><h2>DESCRIPTION</h2>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<p><span><strong class="command">lwresd</strong></span>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi is the daemon providing name lookup
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi services to clients that use the BIND 9 lightweight resolver
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi library. It is essentially a stripped-down, caching-only name
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi server that answers queries using the BIND 9 lightweight
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi resolver protocol rather than the DNS protocol.
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi </p>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<p><span><strong class="command">lwresd</strong></span>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi listens for resolver queries on a
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi UDP port on the IPv4 loopback interface, 127.0.0.1. This
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi means that <span><strong class="command">lwresd</strong></span> can only be used by
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi processes running on the local machine. By default UDP port
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi number 921 is used for lightweight resolver requests and
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi responses.
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi </p>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<p>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi Incoming lightweight resolver requests are decoded by the
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi server which then resolves them using the DNS protocol. When
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi the DNS lookup completes, <span><strong class="command">lwresd</strong></span> encodes
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi the answers in the lightweight resolver format and returns
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi them to the client that made the request.
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi </p>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi<p>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi If <code class="filename">/etc/resolv.conf</code> contains any
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi <code class="option">nameserver</code> entries, <span><strong class="command">lwresd</strong></span>
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi sends recursive DNS queries to those servers. This is similar
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi to the use of forwarders in a caching name server. If no
e433824f46514e6ed863eb6b95c70038331c8c24Nicolas Capponi <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="id2514308"></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="id2514640"></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="id2514679"></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="id2514713"></a><h2>AUTHOR</h2>
<p><span class="corpauthor">Internet Systems Consortium</span>
</p>
</div>
</div></body>
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