contrib/bind9/bin/named/lwresd.html

   1 <!--
   2  - Copyright (C) 2004, 2005, 2007-2009, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
   3  - Copyright (C) 2000, 2001 Internet Software Consortium.
   4  -
   5  - Permission to use, copy, modify, and/or distribute this software for any
   6  - purpose with or without fee is hereby granted, provided that the above
   7  - copyright notice and this permission notice appear in all copies.
   8  -
   9  - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  - PERFORMANCE OF THIS SOFTWARE.
  16 -->
  17 <html>
  18 <head>
  19 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
  20 <title>lwresd</title>
  21 <meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
  22 </head>
  23 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry">
  24 <a name="man.lwresd"></a><div class="titlepage"></div>
  25 <div class="refnamediv">
  26 <h2>Name</h2>
  27 <p><span class="application">lwresd</span> &#8212; lightweight resolver daemon</p>
  28 </div>
  29 <div class="refsynopsisdiv">
  30 <h2>Synopsis</h2>
  31 <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>
  32 </div>
  33 <div class="refsection">
  34 <a name="id-1.7"></a><h2>DESCRIPTION</h2>
  35 <p><span class="command"><strong>lwresd</strong></span>
  36       is the daemon providing name lookup
  37       services to clients that use the BIND 9 lightweight resolver
  38       library.  It is essentially a stripped-down, caching-only name
  39       server that answers queries using the BIND 9 lightweight
  40       resolver protocol rather than the DNS protocol.
  41     </p>
  42 <p><span class="command"><strong>lwresd</strong></span>
  43       listens for resolver queries on a
  44       UDP port on the IPv4 loopback interface, 127.0.0.1.  This
  45       means that <span class="command"><strong>lwresd</strong></span> can only be used by
  46       processes running on the local machine.  By default, UDP port
  47       number 921 is used for lightweight resolver requests and
  48       responses.
  49     </p>
  50 <p>
  51       Incoming lightweight resolver requests are decoded by the
  52       server which then resolves them using the DNS protocol.  When
  53       the DNS lookup completes, <span class="command"><strong>lwresd</strong></span> encodes
  54       the answers in the lightweight resolver format and returns
  55       them to the client that made the request.
  56     </p>
  57 <p>
  58       If <code class="filename">/etc/resolv.conf</code> contains any
  59       <code class="option">nameserver</code> entries, <span class="command"><strong>lwresd</strong></span>
  60       sends recursive DNS queries to those servers.  This is similar
  61       to the use of forwarders in a caching name server.  If no
  62       <code class="option">nameserver</code> entries are present, or if
  63       forwarding fails, <span class="command"><strong>lwresd</strong></span> resolves the
  64       queries autonomously starting at the root name servers, using
  65       a built-in list of root server hints.
  66     </p>
  67 </div>
  68 <div class="refsection">
  69 <a name="id-1.8"></a><h2>OPTIONS</h2>
  70 <div class="variablelist"><dl class="variablelist">
  71 <dt><span class="term">-4</span></dt>
  72 <dd><p>
  73             Use IPv4 only even if the host machine is capable of IPv6.
  74             <code class="option">-4</code> and <code class="option">-6</code> are mutually
  75             exclusive.
  76           </p></dd>
  77 <dt><span class="term">-6</span></dt>
  78 <dd><p>
  79             Use IPv6 only even if the host machine is capable of IPv4.
  80             <code class="option">-4</code> and <code class="option">-6</code> are mutually
  81             exclusive.
  82           </p></dd>
  83 <dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
  84 <dd><p>
  85             Use <em class="replaceable"><code>config-file</code></em> as the
  86             configuration file instead of the default,
  87             <code class="filename">/etc/lwresd.conf</code>.
  88
  89             <code class="option">-c</code> can not be used with <code class="option">-C</code>.
  90           </p></dd>
  91 <dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt>
  92 <dd><p>
  93             Use <em class="replaceable"><code>config-file</code></em> as the
  94             configuration file instead of the default,
  95             <code class="filename">/etc/resolv.conf</code>.
  96             <code class="option">-C</code> can not be used with <code class="option">-c</code>.
  97           </p></dd>
  98 <dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
  99 <dd><p>
 100             Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
 101             Debugging traces from <span class="command"><strong>lwresd</strong></span> become
 102                         more verbose as the debug level increases.
 103           </p></dd>
 104 <dt><span class="term">-f</span></dt>
 105 <dd><p>
 106             Run the server in the foreground (i.e. do not daemonize).
 107           </p></dd>
 108 <dt><span class="term">-g</span></dt>
 109 <dd><p>
 110             Run the server in the foreground and force all logging
 111             to <code class="filename">stderr</code>.
 112           </p></dd>
 113 <dt><span class="term">-i <em class="replaceable"><code>pid-file</code></em></span></dt>
 114 <dd><p>
 115             Use <em class="replaceable"><code>pid-file</code></em> as the
 116             PID file instead of the default,
 117             <code class="filename">/var/run/lwresd/lwresd.pid</code>.
 118           </p></dd>
 119 <dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
 120 <dd><p>
 121             Turn on memory usage debugging flags.  Possible flags are
 122             <em class="replaceable"><code>usage</code></em>,
 123             <em class="replaceable"><code>trace</code></em>,
 124             <em class="replaceable"><code>record</code></em>,
 125             <em class="replaceable"><code>size</code></em>, and
 126             <em class="replaceable"><code>mctx</code></em>.
 127             These correspond to the ISC_MEM_DEBUGXXXX flags described in
 128             <code class="filename">&lt;isc/mem.h&gt;</code>.
 129           </p></dd>
 130 <dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
 131 <dd><p>
 132             Create <em class="replaceable"><code>#cpus</code></em> worker threads
 133             to take advantage of multiple CPUs.  If not specified,
 134             <span class="command"><strong>lwresd</strong></span> will try to determine the
 135             number of CPUs present and create one thread per CPU.
 136             If it is unable to determine the number of CPUs, a
 137             single worker thread will be created.
 138           </p></dd>
 139 <dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt>
 140 <dd><p>
 141             Listen for lightweight resolver queries on port
 142             <em class="replaceable"><code>port</code></em>.  If
 143                         not specified, the default is port 921.
 144           </p></dd>
 145 <dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
 146 <dd><p>
 147             Send DNS lookups to port <em class="replaceable"><code>port</code></em>.  If not
 148             specified, the default is port 53.  This provides a
 149             way of testing the lightweight resolver daemon with a
 150             name server that listens for queries on a non-standard
 151             port number.
 152           </p></dd>
 153 <dt><span class="term">-s</span></dt>
 154 <dd>
 155 <p>
 156             Write memory usage statistics to <code class="filename">stdout</code>
 157             on exit.
 158           </p>
 159 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
 160 <h3 class="title">Note</h3>
 161 <p>
 162               This option is mainly of interest to BIND 9 developers
 163               and may be removed or changed in a future release.
 164             </p>
 165 </div>
 166 </dd>
 167 <dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
 168 <dd>
 169 <p>Chroot
 170             to <em class="replaceable"><code>directory</code></em> after
 171             processing the command line arguments, but before
 172             reading the configuration file.
 173           </p>
 174 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
 175 <h3 class="title">Warning</h3>
 176 <p>
 177               This option should be used in conjunction with the
 178               <code class="option">-u</code> option, as chrooting a process
 179               running as root doesn't enhance security on most
 180               systems; the way <code class="function">chroot(2)</code> is
 181               defined allows a process with root privileges to
 182               escape a chroot jail.
 183             </p>
 184 </div>
 185 </dd>
 186 <dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
 187 <dd><p>Setuid
 188             to <em class="replaceable"><code>user</code></em> after completing
 189             privileged operations, such as creating sockets that
 190             listen on privileged ports.
 191           </p></dd>
 192 <dt><span class="term">-v</span></dt>
 193 <dd><p>
 194             Report the version number and exit.
 195           </p></dd>
 196 </dl></div>
 197 </div>
 198 <div class="refsection">
 199 <a name="id-1.9"></a><h2>FILES</h2>
 200 <div class="variablelist"><dl class="variablelist">
 201 <dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt>
 202 <dd><p>
 203             The default configuration file.
 204           </p></dd>
 205 <dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt>
 206 <dd><p>
 207             The default process-id file.
 208           </p></dd>
 209 </dl></div>
 210 </div>
 211 <div class="refsection">
 212 <a name="id-1.10"></a><h2>SEE ALSO</h2>
 213 <p><span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
 214       <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
 215       <span class="citerefentry"><span class="refentrytitle">resolver</span>(5)</span>.
 216     </p>
 217 </div>
 218 </div></body>
 219 </html>