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60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<a name="man.lwresd"></a><div class="titlepage"></div>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<p><span class="application">lwresd</span> — lightweight resolver daemon</p>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<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">-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">-m <em class="replaceable"><code>flag</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>] [<code class="option">-4</code>] [<code class="option">-6</code>]</p></div>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<p><span class="command"><strong>lwresd</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein is the daemon providing name lookup
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein services to clients that use the BIND 9 lightweight resolver
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein library. It is essentially a stripped-down, caching-only name
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein server that answers queries using the BIND 9 lightweight
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein resolver protocol rather than the DNS protocol.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<p><span class="command"><strong>lwresd</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein listens for resolver queries on a
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein UDP port on the IPv4 loopback interface, 127.0.0.1. This
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein means that <span class="command"><strong>lwresd</strong></span> can only be used by
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein processes running on the local machine. By default, UDP port
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein number 921 is used for lightweight resolver requests and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Incoming lightweight resolver requests are decoded by the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein server which then resolves them using the DNS protocol. When
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein the DNS lookup completes, <span class="command"><strong>lwresd</strong></span> encodes
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein the answers in the lightweight resolver format and returns
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein them to the client that made the request.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein If <code class="filename">/etc/resolv.conf</code> contains any
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">nameserver</code> entries, <span class="command"><strong>lwresd</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein sends recursive DNS queries to those servers. This is similar
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein to the use of forwarders in a caching name server. If no
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">nameserver</code> entries are present, or if
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein forwarding fails, <span class="command"><strong>lwresd</strong></span> resolves the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein queries autonomously starting at the root name servers, using
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein a built-in list of root server hints.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<div class="variablelist"><dl class="variablelist">
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Use IPv4 only even if the host machine is capable of IPv6.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-4</code> and <code class="option">-6</code> are mutually
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Use IPv6 only even if the host machine is capable of IPv4.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-4</code> and <code class="option">-6</code> are mutually
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Use <em class="replaceable"><code>config-file</code></em> as the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein configuration file instead of the default,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-c</code> can not be used with <code class="option">-C</code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Use <em class="replaceable"><code>config-file</code></em> as the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein configuration file instead of the default,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-C</code> can not be used with <code class="option">-c</code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Debugging traces from <span class="command"><strong>lwresd</strong></span> become
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein more verbose as the debug level increases.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Run the server in the foreground (i.e. do not daemonize).
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Run the server in the foreground and force all logging
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-i <em class="replaceable"><code>pid-file</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Use <em class="replaceable"><code>pid-file</code></em> as the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein PID file instead of the default,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="filename">/var/run/lwresd/lwresd.pid</code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Turn on memory usage debugging flags. Possible flags are
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="replaceable"><code>usage</code></em>,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="replaceable"><code>trace</code></em>,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="replaceable"><code>record</code></em>,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="replaceable"><code>size</code></em>, and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein These correspond to the ISC_MEM_DEBUGXXXX flags described in
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="filename"><isc/mem.h></code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Create <em class="replaceable"><code>#cpus</code></em> worker threads
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein to take advantage of multiple CPUs. If not specified,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="command"><strong>lwresd</strong></span> will try to determine the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein number of CPUs present and create one thread per CPU.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein If it is unable to determine the number of CPUs, a
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein single worker thread will be created.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Listen for lightweight resolver queries on port
b0e8629055a766d4555a005a283c2889a5974945Mark Andrews <em class="replaceable"><code>port</code></em>. If
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein not specified, the default is port 921.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Send DNS lookups to port <em class="replaceable"><code>port</code></em>. If not
90153b6536f7a5078e1c157c980110dbcd7fe205Mark Andrews specified, the default is port 53. This provides a
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein way of testing the lightweight resolver daemon with a
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein name server that listens for queries on a non-standard
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein port number.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Write memory usage statistics to <code class="filename">stdout</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
d71e2e0c61df16ff37c9934c371a4a60c08974f7Mark Andrews This option is mainly of interest to BIND 9 developers
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein and may be removed or changed in a future release.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein to <em class="replaceable"><code>directory</code></em> after
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein processing the command line arguments, but before
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein reading the configuration file.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
d71e2e0c61df16ff37c9934c371a4a60c08974f7Mark Andrews This option should be used in conjunction with the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-u</code> option, as chrooting a process
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein running as root doesn't enhance security on most
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein systems; the way <code class="function">chroot(2)</code> is
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein defined allows a process with root privileges to
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein escape a chroot jail.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
b0e8629055a766d4555a005a283c2889a5974945Mark Andrews to <em class="replaceable"><code>user</code></em> after completing
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein privileged operations, such as creating sockets that
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein listen on privileged ports.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Report the version number and exit.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<div class="variablelist"><dl class="variablelist">
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The default configuration file.
d71e2e0c61df16ff37c9934c371a4a60c08974f7Mark Andrews<dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The default process-id file.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<p><span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>.