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- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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<title>lwresd</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
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<a name="id2463721"></a><div class="titlepage"></div>
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<a name="id2476275"></a><div class="titlepage"></div>
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<div class="refnamediv">
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<p><span class="application">lwresd</span> — lightweight resolver daemon</p>
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<div class="refsynopsisdiv">
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<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>
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<div class="refsect1" lang="en">
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<a name="id2525920"></a><h2>DESCRIPTION</h2>
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<span><strong class="command">lwresd</strong></span> is the daemon providing name lookup
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services to clients that use the BIND 9 lightweight resolver
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library. It is essentially a stripped-down, caching-only name
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server that answers queries using the BIND 9 lightweight
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resolver protocol rather than the DNS protocol.
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<span><strong class="command">lwresd</strong></span> listens for resolver queries on a
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UDP port on the IPv4 loopback interface, 127.0.0.1. This
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means that <span><strong class="command">lwresd</strong></span> can only be used by
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processes running on the local machine. By default UDP port
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number 921 is used for lightweight resolver requests and
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Incoming lightweight resolver requests are decoded by the
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server which then resolves them using the DNS protocol. When
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the DNS lookup completes, <span><strong class="command">lwresd</strong></span> encodes
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the answers in the lightweight resolver format and returns
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them to the client that made the request.
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If <code class="filename">/etc/resolv.conf</code> contains any
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<code class="option">nameserver</code> entries, <span><strong class="command">lwresd</strong></span>
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sends recursive DNS queries to those servers. This is similar
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to the use of forwarders in a caching name server. If no
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<code class="option">nameserver</code> entries are present, or if
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forwarding fails, <span><strong class="command">lwresd</strong></span> resolves the
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queries autonomously starting at the root name servers, using
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a built-in list of root server hints.
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<div class="refsect1" lang="en">
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<a name="id2525969"></a><h2>OPTIONS</h2>
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<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>
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<div class="refsect1" lang="en">
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<a name="id2543461"></a><h2>DESCRIPTION</h2>
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<p><span><strong class="command">lwresd</strong></span>
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is the daemon providing name lookup
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services to clients that use the BIND 9 lightweight resolver
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library. It is essentially a stripped-down, caching-only name
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server that answers queries using the BIND 9 lightweight
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resolver protocol rather than the DNS protocol.
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<p><span><strong class="command">lwresd</strong></span>
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listens for resolver queries on a
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UDP port on the IPv4 loopback interface, 127.0.0.1. This
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means that <span><strong class="command">lwresd</strong></span> can only be used by
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processes running on the local machine. By default UDP port
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number 921 is used for lightweight resolver requests and
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Incoming lightweight resolver requests are decoded by the
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server which then resolves them using the DNS protocol. When
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the DNS lookup completes, <span><strong class="command">lwresd</strong></span> encodes
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the answers in the lightweight resolver format and returns
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them to the client that made the request.
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If <code class="filename">/etc/resolv.conf</code> contains any
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<code class="option">nameserver</code> entries, <span><strong class="command">lwresd</strong></span>
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sends recursive DNS queries to those servers. This is similar
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to the use of forwarders in a caching name server. If no
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<code class="option">nameserver</code> entries are present, or if
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forwarding fails, <span><strong class="command">lwresd</strong></span> resolves the
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queries autonomously starting at the root name servers, using
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a built-in list of root server hints.
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<div class="refsect1" lang="en">
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<a name="id2543508"></a><h2>OPTIONS</h2>
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<div class="variablelist"><dl>
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<dt><span class="term">-4</span></dt>
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Use IPv4 only even if the host machine is capable of IPv6.
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<code class="option">-4</code> and <code class="option">-6</code> are mutually
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<dt><span class="term">-6</span></dt>
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Use IPv6 only even if the host machine is capable of IPv4.
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<code class="option">-4</code> and <code class="option">-6</code> are mutually
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<dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
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Use <em class="replaceable"><code>config-file</code></em> as the
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configuration file instead of the default,
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<code class="filename">/etc/lwresd.conf</code>.
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<font color="red"><term>-c</term></font> can not be used with <font color="red"><term>-C</term></font>.
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<dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt>
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Use <em class="replaceable"><code>config-file</code></em> as the
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configuration file instead of the default,
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<code class="filename">/etc/resolv.conf</code>.
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Use <em class="replaceable"><code>config-file</code></em> as the
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configuration file instead of the default,
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<code class="filename">/etc/resolv.conf</code>.
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<font color="red"><term>-C</term></font> can not be used with <font color="red"><term>-c</term></font>.
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<dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
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Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
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Debugging traces from <span><strong class="command">lwresd</strong></span> become
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more verbose as the debug level increases.
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Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
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Debugging traces from <span><strong class="command">lwresd</strong></span> become
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more verbose as the debug level increases.
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<dt><span class="term">-f</span></dt>
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Run the server in the foreground (i.e. do not daemonize).
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Run the server in the foreground (i.e. do not daemonize).
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<dt><span class="term">-g</span></dt>
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Run the server in the foreground and force all logging
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to <code class="filename">stderr</code>.
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Run the server in the foreground and force all logging
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to <code class="filename">stderr</code>.
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<dt><span class="term">-i <em class="replaceable"><code>pid-file</code></em></span></dt>
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Use <em class="replaceable"><code>pid-file</code></em> as the
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PID file instead of the default,
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<code class="filename">/var/run/lwresd.pid</code>.
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<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
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Turn on memory usage debugging flags. Possible flags are
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<em class="replaceable"><code>usage</code></em>,
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<em class="replaceable"><code>trace</code></em>,
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<em class="replaceable"><code>record</code></em>,
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<em class="replaceable"><code>size</code></em>, and
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<em class="replaceable"><code>mctx</code></em>.
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These correspond to the ISC_MEM_DEBUGXXXX flags described in
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<code class="filename"><isc/mem.h></code>.
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<dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
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Create <em class="replaceable"><code>#cpus</code></em> worker threads
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to take advantage of multiple CPUs. If not specified,
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<span><strong class="command">lwresd</strong></span> will try to determine the
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number of CPUs present and create one thread per CPU.
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If it is unable to determine the number of CPUs, a
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single worker thread will be created.
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Create <em class="replaceable"><code>#cpus</code></em> worker threads
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to take advantage of multiple CPUs. If not specified,
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<span><strong class="command">lwresd</strong></span> will try to determine the
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number of CPUs present and create one thread per CPU.
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If it is unable to determine the number of CPUs, a
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single worker thread will be created.
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<dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt>
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Listen for lightweight resolver queries on port
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<em class="replaceable"><code>port</code></em>. If
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not specified, the default is port 921.
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Listen for lightweight resolver queries on port
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<em class="replaceable"><code>port</code></em>. If
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not specified, the default is port 921.
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<dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
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Send DNS lookups to port <em class="replaceable"><code>port</code></em>. If not
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specified, the default is port 53. This provides a
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way of testing the lightweight resolver daemon with a
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name server that listens for queries on a non-standard
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Send DNS lookups to port <em class="replaceable"><code>port</code></em>. If not
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specified, the default is port 53. This provides a
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way of testing the lightweight resolver daemon with a
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name server that listens for queries on a non-standard
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<dt><span class="term">-s</span></dt>
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Write memory usage statistics to <code class="filename">stdout</code>
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Write memory usage statistics to <code class="filename">stdout</code>
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<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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This option is mainly of interest to BIND 9 developers
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and may be removed or changed in a future release.
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This option is mainly of interest to BIND 9 developers
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and may be removed or changed in a future release.
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<dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
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<code class="function">chroot()</code> to <em class="replaceable"><code>directory</code></em> after
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processing the command line arguments, but before
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reading the configuration file.
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to <em class="replaceable"><code>directory</code></em> after
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processing the command line arguments, but before
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reading the configuration file.
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<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Warning</h3>
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This option should be used in conjunction with the
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<code class="option">-u</code> option, as chrooting a process
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running as root doesn't enhance security on most
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systems; the way <code class="function">chroot()</code> is
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defined allows a process with root privileges to
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escape a chroot jail.
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This option should be used in conjunction with the
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<code class="option">-u</code> option, as chrooting a process
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running as root doesn't enhance security on most
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systems; the way <code class="function">chroot(2)</code> is
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defined allows a process with root privileges to
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escape a chroot jail.
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<dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
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<code class="function">setuid()</code> to <em class="replaceable"><code>user</code></em> after completing
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privileged operations, such as creating sockets that
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listen on privileged ports.
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to <em class="replaceable"><code>user</code></em> after completing
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privileged operations, such as creating sockets that
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listen on privileged ports.
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<dt><span class="term">-v</span></dt>
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Report the version number and exit.
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Report the version number and exit.
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<div class="refsect1" lang="en">
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<a name="id2526237"></a><h2>FILES</h2>
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<a name="id2543925"></a><h2>FILES</h2>
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<div class="variablelist"><dl>
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<dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt>
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The default configuration file.
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The default configuration file.
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<dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt>
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The default process-id file.
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The default process-id file.
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<div class="refsect1" lang="en">
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<a name="id2526277"></a><h2>SEE ALSO</h2>
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<span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
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<span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
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<span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>.
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<a name="id2543964"></a><h2>SEE ALSO</h2>
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<p><span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
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<span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
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<span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>.
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<div class="refsect1" lang="en">
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<a name="id2526315"></a><h2>AUTHOR</h2>
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<span class="corpauthor">Internet Systems Consortium</span>
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<a name="id2543998"></a><h2>AUTHOR</h2>
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<p><span class="corpauthor">Internet Systems Consortium</span>
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