contrib/bind-9.5.2/bin/named/lwresd.html

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  21 <title>lwresd</title>
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  24 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
  25 <a name="id2476275"></a><div class="titlepage"></div>
  26 <div class="refnamediv">
  27 <h2>Name</h2>
  28 <p><span class="application">lwresd</span> &#8212; lightweight resolver daemon</p>
  29 </div>
  30 <div class="refsynopsisdiv">
  31 <h2>Synopsis</h2>
  32 <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>
  33 </div>
  34 <div class="refsect1" lang="en">
  35 <a name="id2543467"></a><h2>DESCRIPTION</h2>
  36 <p><span><strong class="command">lwresd</strong></span>
  37       is the daemon providing name lookup
  38       services to clients that use the BIND 9 lightweight resolver
  39       library.  It is essentially a stripped-down, caching-only name
  40       server that answers queries using the BIND 9 lightweight
  41       resolver protocol rather than the DNS protocol.
  42     </p>
  43 <p><span><strong class="command">lwresd</strong></span>
  44       listens for resolver queries on a
  45       UDP port on the IPv4 loopback interface, 127.0.0.1.  This
  46       means that <span><strong class="command">lwresd</strong></span> can only be used by
  47       processes running on the local machine.  By default, UDP port
  48       number 921 is used for lightweight resolver requests and
  49       responses.
  50     </p>
  51 <p>
  52       Incoming lightweight resolver requests are decoded by the
  53       server which then resolves them using the DNS protocol.  When
  54       the DNS lookup completes, <span><strong class="command">lwresd</strong></span> encodes
  55       the answers in the lightweight resolver format and returns
  56       them to the client that made the request.
  57     </p>
  58 <p>
  59       If <code class="filename">/etc/resolv.conf</code> contains any
  60       <code class="option">nameserver</code> entries, <span><strong class="command">lwresd</strong></span>
  61       sends recursive DNS queries to those servers.  This is similar
  62       to the use of forwarders in a caching name server.  If no
  63       <code class="option">nameserver</code> entries are present, or if
  64       forwarding fails, <span><strong class="command">lwresd</strong></span> resolves the
  65       queries autonomously starting at the root name servers, using
  66       a built-in list of root server hints.
  67     </p>
  68 </div>
  69 <div class="refsect1" lang="en">
  70 <a name="id2543514"></a><h2>OPTIONS</h2>
  71 <div class="variablelist"><dl>
  72 <dt><span class="term">-4</span></dt>
  73 <dd><p>
  74             Use IPv4 only even if the host machine is capable of IPv6.
  75             <code class="option">-4</code> and <code class="option">-6</code> are mutually
  76             exclusive.
  77           </p></dd>
  78 <dt><span class="term">-6</span></dt>
  79 <dd><p>
  80             Use IPv6 only even if the host machine is capable of IPv4.
  81             <code class="option">-4</code> and <code class="option">-6</code> are mutually
  82             exclusive.
  83           </p></dd>
  84 <dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
  85 <dd><p>
  86             Use <em class="replaceable"><code>config-file</code></em> as the
  87             configuration file instead of the default,
  88             <code class="filename">/etc/lwresd.conf</code>.
  89
  90             <code class="option">-c</code> can not be used with <code class="option">-C</code>.
  91           </p></dd>
  92 <dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt>
  93 <dd><p>
  94             Use <em class="replaceable"><code>config-file</code></em> as the
  95             configuration file instead of the default,
  96             <code class="filename">/etc/resolv.conf</code>.
  97             <code class="option">-C</code> can not be used with <code class="option">-c</code>.
  98           </p></dd>
  99 <dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
 100 <dd><p>
 101             Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
 102             Debugging traces from <span><strong class="command">lwresd</strong></span> become
 103                         more verbose as the debug level increases.
 104           </p></dd>
 105 <dt><span class="term">-f</span></dt>
 106 <dd><p>
 107             Run the server in the foreground (i.e. do not daemonize).
 108           </p></dd>
 109 <dt><span class="term">-g</span></dt>
 110 <dd><p>
 111             Run the server in the foreground and force all logging
 112             to <code class="filename">stderr</code>.
 113           </p></dd>
 114 <dt><span class="term">-i <em class="replaceable"><code>pid-file</code></em></span></dt>
 115 <dd><p>
 116             Use <em class="replaceable"><code>pid-file</code></em> as the
 117             PID file instead of the default,
 118             <code class="filename">/var/run/lwresd.pid</code>.
 119           </p></dd>
 120 <dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
 121 <dd><p>
 122             Turn on memory usage debugging flags.  Possible flags are
 123             <em class="replaceable"><code>usage</code></em>,
 124             <em class="replaceable"><code>trace</code></em>,
 125             <em class="replaceable"><code>record</code></em>,
 126             <em class="replaceable"><code>size</code></em>, and
 127             <em class="replaceable"><code>mctx</code></em>.
 128             These correspond to the ISC_MEM_DEBUGXXXX flags described in
 129             <code class="filename">&lt;isc/mem.h&gt;</code>.
 130           </p></dd>
 131 <dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
 132 <dd><p>
 133             Create <em class="replaceable"><code>#cpus</code></em> worker threads
 134             to take advantage of multiple CPUs.  If not specified,
 135             <span><strong class="command">lwresd</strong></span> will try to determine the
 136             number of CPUs present and create one thread per CPU.
 137             If it is unable to determine the number of CPUs, a
 138             single worker thread will be created.
 139           </p></dd>
 140 <dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt>
 141 <dd><p>
 142             Listen for lightweight resolver queries on port
 143             <em class="replaceable"><code>port</code></em>.  If
 144                         not specified, the default is port 921.
 145           </p></dd>
 146 <dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
 147 <dd><p>
 148             Send DNS lookups to port <em class="replaceable"><code>port</code></em>.  If not
 149             specified, the default is port 53.  This provides a
 150             way of testing the lightweight resolver daemon with a
 151             name server that listens for queries on a non-standard
 152             port number.
 153           </p></dd>
 154 <dt><span class="term">-s</span></dt>
 155 <dd>
 156 <p>
 157             Write memory usage statistics to <code class="filename">stdout</code>
 158             on exit.
 159           </p>
 160 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
 161 <h3 class="title">Note</h3>
 162 <p>
 163               This option is mainly of interest to BIND 9 developers
 164               and may be removed or changed in a future release.
 165             </p>
 166 </div>
 167 </dd>
 168 <dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
 169 <dd>
 170 <p>Chroot
 171             to <em class="replaceable"><code>directory</code></em> after
 172             processing the command line arguments, but before
 173             reading the configuration file.
 174           </p>
 175 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
 176 <h3 class="title">Warning</h3>
 177 <p>
 178               This option should be used in conjunction with the
 179               <code class="option">-u</code> option, as chrooting a process
 180               running as root doesn't enhance security on most
 181               systems; the way <code class="function">chroot(2)</code> is
 182               defined allows a process with root privileges to
 183               escape a chroot jail.
 184             </p>
 185 </div>
 186 </dd>
 187 <dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
 188 <dd><p>Setuid
 189             to <em class="replaceable"><code>user</code></em> after completing
 190             privileged operations, such as creating sockets that
 191             listen on privileged ports.
 192           </p></dd>
 193 <dt><span class="term">-v</span></dt>
 194 <dd><p>
 195             Report the version number and exit.
 196           </p></dd>
 197 </dl></div>
 198 </div>
 199 <div class="refsect1" lang="en">
 200 <a name="id2543931"></a><h2>FILES</h2>
 201 <div class="variablelist"><dl>
 202 <dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt>
 203 <dd><p>
 204             The default configuration file.
 205           </p></dd>
 206 <dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt>
 207 <dd><p>
 208             The default process-id file.
 209           </p></dd>
 210 </dl></div>
 211 </div>
 212 <div class="refsect1" lang="en">
 213 <a name="id2543971"></a><h2>SEE ALSO</h2>
 214 <p><span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
 215       <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
 216       <span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>.
 217     </p>
 218 </div>
 219 <div class="refsect1" lang="en">
 220 <a name="id2544005"></a><h2>AUTHOR</h2>
 221 <p><span class="corpauthor">Internet Systems Consortium</span>
 222     </p>
 223 </div>
 224 </div></body>
 225 </html>