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div class="refentry" lang="en">
1879N/A<
a name="id2482688"></
a><
div class="titlepage"></
div>
1879N/A<
p><
span class="application">lwresd</
span> — lightweight resolver daemon</
p>
1879N/A<
div class="refsynopsisdiv">
1879N/A<
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>
1879N/A<
div class="refsect1" lang="en">
1879N/A<
a name="id2549493"></
a><
h2>DESCRIPTION</
h2>
1879N/A<
p><
span><
strong class="command">lwresd</
strong></
span>
1879N/A is the daemon providing name lookup
1879N/A services to clients that use the BIND 9 lightweight resolver
1879N/A library. It is essentially a stripped-down, caching-only name
1879N/A server that answers queries using the BIND 9 lightweight
1879N/A resolver protocol rather than the DNS protocol.
1879N/A<
p><
span><
strong class="command">lwresd</
strong></
span>
1879N/A listens for resolver queries on a
1879N/A UDP port on the IPv4 loopback interface, 127.0.0.1. This
1879N/A means that <
span><
strong class="command">lwresd</
strong></
span> can only be used by
1879N/A processes running on the local machine. By default UDP port
1879N/A number 921 is used for lightweight resolver requests and
1879N/A Incoming lightweight resolver requests are decoded by the
1879N/A server which then resolves them using the DNS protocol. When
1879N/A the DNS lookup completes, <
span><
strong class="command">lwresd</
strong></
span> encodes
1879N/A the answers in the lightweight resolver format and returns
0N/A them to the client that made the request.
0N/A <
code class="option">nameserver</
code> entries, <
span><
strong class="command">lwresd</
strong></
span>
0N/A sends recursive DNS queries to those servers. This is similar
0N/A to the use of forwarders in a caching name server. If no
0N/A <
code class="option">nameserver</
code> entries are present, or if
1798N/A forwarding fails, <
span><
strong class="command">lwresd</
strong></
span> resolves the
0N/A queries autonomously starting at the root name servers, using
0N/A a built-in list of root server hints.
0N/A<
div class="refsect1" lang="en">
0N/A<
a name="id2549540"></
a><
h2>OPTIONS</
h2>
0N/A<
div class="variablelist"><
dl>
0N/A<
dt><
span class="term">-C <
em class="replaceable"><
code>config-file</
code></
em></
span></
dt>
0N/A Use <
em class="replaceable"><
code>config-file</
code></
em> as the
0N/A configuration file instead of the default,
0N/A<
dt><
span class="term">-d <
em class="replaceable"><
code>debug-level</
code></
em></
span></
dt>
0N/A Set the daemon's debug level to <
em class="replaceable"><
code>debug-level</
code></
em>.
1881N/A Debugging traces from <
span><
strong class="command">lwresd</
strong></
span> become
1881N/A more verbose as the debug level increases.
0N/A<
dt><
span class="term">-f</
span></
dt>
1119N/A Run the server in the foreground (
i.e. do not daemonize).
1119N/A<
dt><
span class="term">-g</
span></
dt>
1119N/A Run the server in the foreground and force all logging
0N/A to <
code class="filename">stderr</
code>.
0N/A<
dt><
span class="term">-n <
em class="replaceable"><
code>#cpus</
code></
em></
span></
dt>
0N/A Create <
em class="replaceable"><
code>#cpus</
code></
em> worker threads
0N/A to take advantage of multiple CPUs. If not specified,
0N/A <
span><
strong class="command">lwresd</
strong></
span> will try to determine the
0N/A number of CPUs present and create one thread per CPU.
0N/A If it is unable to determine the number of CPUs, a
0N/A single worker thread will be created.
0N/A<
dt><
span class="term">-P <
em class="replaceable"><
code>port</
code></
em></
span></
dt>
0N/A Listen for lightweight resolver queries on port
0N/A <
em class="replaceable"><
code>port</
code></
em>. If
0N/A not specified, the default is port 921.
0N/A<
dt><
span class="term">-p <
em class="replaceable"><
code>port</
code></
em></
span></
dt>
0N/A Send DNS lookups to port <
em class="replaceable"><
code>port</
code></
em>. If not
0N/A specified, the default is port 53. This provides a
0N/A way of testing the lightweight resolver daemon with a
0N/A name server that listens for queries on a non-standard
0N/A<
dt><
span class="term">-s</
span></
dt>
0N/A Write memory usage statistics to <
code class="filename">stdout</
code>
0N/A<
div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
0N/A<
h3 class="title">Note</
h3>
0N/A This option is mainly of interest to BIND 9 developers
0N/A and may be removed or changed in a future release.
0N/A<
dt><
span class="term">-t <
em class="replaceable"><
code>directory</
code></
em></
span></
dt>
0N/A<
p><
code class="function">chroot()</
code>
0N/A to <
em class="replaceable"><
code>directory</
code></
em> after
0N/A processing the command line arguments, but before
0N/A reading the configuration file.
0N/A<
div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
0N/A<
h3 class="title">Warning</
h3>
0N/A This option should be used in conjunction with the
0N/A <
code class="option">-u</
code> option, as chrooting a process
0N/A running as root doesn't enhance security on most
0N/A systems; the way <
code class="function">chroot()</
code> is
0N/A defined allows a process with root privileges to
0N/A escape a chroot jail.
0N/A<
dt><
span class="term">-u <
em class="replaceable"><
code>user</
code></
em></
span></
dt>
0N/A<
dd><
p><
code class="function">setuid()</
code>
0N/A to <
em class="replaceable"><
code>user</
code></
em> after completing
0N/A privileged operations, such as creating sockets that
0N/A listen on privileged ports.
0N/A<
dt><
span class="term">-v</
span></
dt>
0N/A Report the version number and exit.
0N/A<
div class="refsect1" lang="en">
0N/A<
a name="id2549940"></
a><
h2>FILES</
h2>
0N/A<
div class="variablelist"><
dl>
0N/A The default configuration file.
0N/A The default process-id file.
0N/A<
div class="refsect1" lang="en">
0N/A<
a name="id2549979"></
a><
h2>SEE ALSO</
h2>
0N/A<
p><
span class="citerefentry"><
span class="refentrytitle">named</
span>(8)</
span>,
0N/A <
span class="citerefentry"><
span class="refentrytitle">lwres</
span>(3)</
span>,
0N/A <
span class="citerefentry"><
span class="refentrytitle">resolver</
span>(5)</
span>.
0N/A<
div class="refsect1" lang="en">
0N/A<
a name="id2550013"></
a><
h2>AUTHOR</
h2>
0N/A<
p><
span class="corpauthor">Internet Systems Consortium</
span>