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36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder<p><span class="application">lwresd</span> — lightweight resolver daemon</p>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder<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>
61e38a4f194d3adc66646326c938eb9263a2f39bChristian Maeder<a name="id-1.14.16.7"></a><h2>DESCRIPTION</h2>
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder<p><span class="command"><strong>lwresd</strong></span>
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder is the daemon providing name lookup
42c01284bba8d7c8d995c8dfb96ace57d28ed1bcTill Mossakowski services to clients that use the BIND 9 lightweight resolver
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder library. It is essentially a stripped-down, caching-only name
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder server that answers queries using the BIND 9 lightweight
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder resolver protocol rather than the DNS protocol.
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder<p><span class="command"><strong>lwresd</strong></span>
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder listens for resolver queries on a
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder UDP port on the IPv4 loopback interface, 127.0.0.1. This
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder means that <span class="command"><strong>lwresd</strong></span> can only be used by
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder processes running on the local machine. By default, UDP port
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder number 921 is used for lightweight resolver requests and
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder Incoming lightweight resolver requests are decoded by the
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder server which then resolves them using the DNS protocol. When
c18e9c3c6d5039618f1f2c05526ece84c7794ea3Christian Maeder the DNS lookup completes, <span class="command"><strong>lwresd</strong></span> encodes
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder the answers in the lightweight resolver format and returns
81946e2b3f6dde6167f48769bd02c7a634736856Christian Maeder them to the client that made the request.
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder If <code class="filename">/etc/resolv.conf</code> contains any
81946e2b3f6dde6167f48769bd02c7a634736856Christian Maeder <code class="option">nameserver</code> entries, <span class="command"><strong>lwresd</strong></span>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder sends recursive DNS queries to those servers. This is similar
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder to the use of forwarders in a caching name server. If no
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder <code class="option">nameserver</code> entries are present, or if
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder forwarding fails, <span class="command"><strong>lwresd</strong></span> resolves the
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder queries autonomously starting at the root name servers, using
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder a built-in list of root server hints.
6b1153c560b677f9f5da2a60ee8a10de75ff90c5Christian Maeder<div class="variablelist"><dl class="variablelist">
ac510075311023bf24175f7a76b89ec2bbda0626Christian Maeder Use IPv4 only even if the host machine is capable of IPv6.
81946e2b3f6dde6167f48769bd02c7a634736856Christian Maeder <code class="option">-4</code> and <code class="option">-6</code> are mutually
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Use IPv6 only even if the host machine is capable of IPv4.
fc752f50cae4154623a01de6a55b897e0aad2c10Christian Maeder <code class="option">-4</code> and <code class="option">-6</code> are mutually
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder<dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
6b1153c560b677f9f5da2a60ee8a10de75ff90c5Christian Maeder Use <em class="replaceable"><code>config-file</code></em> as the
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder configuration file instead of the default,
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder <code class="filename">/etc/lwresd.conf</code>.
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder <code class="option">-c</code> can not be used with <code class="option">-C</code>.
25a0b76bc87e80c0f697951d9817862755a71d33Christian Maeder<dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Use <em class="replaceable"><code>config-file</code></em> as the
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder configuration file instead of the default,
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder <code class="filename">/etc/resolv.conf</code>.
b2e5126cfa94e91e1e8b7fc39bb3fccaa286e77fChristian Maeder <code class="option">-C</code> can not be used with <code class="option">-c</code>.
6b1153c560b677f9f5da2a60ee8a10de75ff90c5Christian Maeder<dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder Debugging traces from <span class="command"><strong>lwresd</strong></span> become
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder more verbose as the debug level increases.
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Run the server in the foreground (i.e. do not daemonize).
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Run the server in the foreground and force all logging
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder<dt><span class="term">-i <em class="replaceable"><code>pid-file</code></em></span></dt>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Use <em class="replaceable"><code>pid-file</code></em> as the
6b1153c560b677f9f5da2a60ee8a10de75ff90c5Christian Maeder PID file instead of the default,
6b1153c560b677f9f5da2a60ee8a10de75ff90c5Christian Maeder <code class="filename">/var/run/lwresd/lwresd.pid</code>.
25a0b76bc87e80c0f697951d9817862755a71d33Christian Maeder<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
81946e2b3f6dde6167f48769bd02c7a634736856Christian Maeder Turn on memory usage debugging flags. Possible flags are
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder <em class="replaceable"><code>usage</code></em>,
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder <em class="replaceable"><code>trace</code></em>,
b645cf3dc1e449038ed291bbd11fcc6e02b2fc7fChristian Maeder <em class="replaceable"><code>record</code></em>,
81946e2b3f6dde6167f48769bd02c7a634736856Christian Maeder <em class="replaceable"><code>size</code></em>, and
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder <em class="replaceable"><code>mctx</code></em>.
6b1153c560b677f9f5da2a60ee8a10de75ff90c5Christian Maeder These correspond to the ISC_MEM_DEBUGXXXX flags described in
81946e2b3f6dde6167f48769bd02c7a634736856Christian Maeder <code class="filename"><isc/mem.h></code>.
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder<dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Create <em class="replaceable"><code>#cpus</code></em> worker threads
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder to take advantage of multiple CPUs. If not specified,
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder <span class="command"><strong>lwresd</strong></span> will try to determine the
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder number of CPUs present and create one thread per CPU.
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder If it is unable to determine the number of CPUs, a
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder single worker thread will be created.
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder<dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Listen for lightweight resolver queries on port
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder <em class="replaceable"><code>port</code></em>. If
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder not specified, the default is port 921.
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder<dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder Send DNS lookups to port <em class="replaceable"><code>port</code></em>. If not
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder specified, the default is port 53. This provides a
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder way of testing the lightweight resolver daemon with a
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder name server that listens for queries on a non-standard
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder Write memory usage statistics to <code class="filename">stdout</code>
64558a09e6f6b95d2689d02dd5251339f8ac505bChristian Maeder<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
8a1f427564a5ae2db32332512237ef645289c34dChristian Maeder This option is mainly of interest to BIND 9 developers
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder and may be removed or changed in a future release.
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder<dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder to <em class="replaceable"><code>directory</code></em> after
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder processing the command line arguments, but before
ae464ac109d82566feab1acbc98eab3bf1f10bb3Christian Maeder reading the configuration file.
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder This option should be used in conjunction with the
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder <code class="option">-u</code> option, as chrooting a process
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder running as root doesn't enhance security on most
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder systems; the way <code class="function">chroot(2)</code> is
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder defined allows a process with root privileges to
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder escape a chroot jail.
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder<dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder to <em class="replaceable"><code>user</code></em> after completing
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder privileged operations, such as creating sockets that
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder listen on privileged ports.
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder Report the version number and exit.
529f678f015ae5276f87da63114cdce750b366aeChristian Maeder<div class="variablelist"><dl class="variablelist">
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder<dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt>
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder The default configuration file.
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder<dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt>
8a0bf74e3923774ce08685de55cc91ccf75a2e3dChristian Maeder The default process-id file.
414ffa281d82f05a2d742c702f8e06b0cb05b229Christian Maeder<a name="id-1.14.16.10"></a><h2>SEE ALSO</h2>
ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder<p><span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
a4edb47c12ef090dbb8a5eaaed73006ad534e680Christian Maeder <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
36333a9f6aa7a251b97336fedaa25064a868f32dChristian Maeder <span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>.
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ecb2c1b15ed2dbca1cba391a8f4de65c60952d6bChristian Maeder<p xmlns:db="http://docbook.org/ns/docbook" style="text-align: center;">BIND 9.11.0rc1</p>