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42 <div class="refentry" lang="en">
43 <a name="man.named"></a><div class="titlepage"></div>
44 <div class="refnamediv">
46 <p><span class="application">named</span> — Internet domain name server</p>
48 <div class="refsynopsisdiv">
50 <div class="cmdsynopsis"><p><code class="command">named</code> [<code class="option">-4</code>] [<code class="option">-6</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">-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">-s</code>] [<code class="option">-S <em class="replaceable"><code>#max-socks</code></em></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">-V</code>] [<code class="option">-x <em class="replaceable"><code>cache-file</code></em></code>]</p></div>
52 <div class="refsect1" lang="en">
53 <a name="id2610525"></a><h2>DESCRIPTION</h2>
54 <p><span><strong class="command">named</strong></span>
55 is a Domain Name System (DNS) server,
56 part of the BIND 9 distribution from ISC. For more
57 information on the DNS, see RFCs 1033, 1034, and 1035.
60 When invoked without arguments, <span><strong class="command">named</strong></span>
62 read the default configuration file
63 <code class="filename">/etc/named.conf</code>, read any initial
64 data, and listen for queries.
67 <div class="refsect1" lang="en">
68 <a name="id2610556"></a><h2>OPTIONS</h2>
69 <div class="variablelist"><dl>
70 <dt><span class="term">-4</span></dt>
72 Use IPv4 only even if the host machine is capable of IPv6.
73 <code class="option">-4</code> and <code class="option">-6</code> are mutually
76 <dt><span class="term">-6</span></dt>
78 Use IPv6 only even if the host machine is capable of IPv4.
79 <code class="option">-4</code> and <code class="option">-6</code> are mutually
82 <dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
84 Use <em class="replaceable"><code>config-file</code></em> as the
85 configuration file instead of the default,
86 <code class="filename">/etc/named.conf</code>. To
87 ensure that reloading the configuration file continues
88 to work after the server has changed its working
89 directory due to to a possible
90 <code class="option">directory</code> option in the configuration
91 file, <em class="replaceable"><code>config-file</code></em> should be
94 <dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
96 Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
97 Debugging traces from <span><strong class="command">named</strong></span> become
98 more verbose as the debug level increases.
100 <dt><span class="term">-f</span></dt>
102 Run the server in the foreground (i.e. do not daemonize).
104 <dt><span class="term">-g</span></dt>
106 Run the server in the foreground and force all logging
107 to <code class="filename">stderr</code>.
109 <dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
111 Turn on memory usage debugging flags. Possible flags are
112 <em class="replaceable"><code>usage</code></em>,
113 <em class="replaceable"><code>trace</code></em>,
114 <em class="replaceable"><code>record</code></em>,
115 <em class="replaceable"><code>size</code></em>, and
116 <em class="replaceable"><code>mctx</code></em>.
117 These correspond to the ISC_MEM_DEBUGXXXX flags described in
118 <code class="filename"><isc/mem.h></code>.
120 <dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
122 Create <em class="replaceable"><code>#cpus</code></em> worker threads
123 to take advantage of multiple CPUs. If not specified,
124 <span><strong class="command">named</strong></span> will try to determine the
125 number of CPUs present and create one thread per CPU.
126 If it is unable to determine the number of CPUs, a
127 single worker thread will be created.
129 <dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
131 Listen for queries on port <em class="replaceable"><code>port</code></em>. If not
132 specified, the default is port 53.
134 <dt><span class="term">-s</span></dt>
137 Write memory usage statistics to <code class="filename">stdout</code> on exit.
139 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
140 <h3 class="title">Note</h3>
142 This option is mainly of interest to BIND 9 developers
143 and may be removed or changed in a future release.
147 <dt><span class="term">-S <em class="replaceable"><code>#max-socks</code></em></span></dt>
150 Allow <span><strong class="command">named</strong></span> to use up to
151 <em class="replaceable"><code>#max-socks</code></em> sockets.
153 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
154 <h3 class="title">Warning</h3>
156 This option should be unnecessary for the vast majority
158 The use of this option could even be harmful because the
159 specified value may exceed the limitation of the
160 underlying system API.
161 It is therefore set only when the default configuration
162 causes exhaustion of file descriptors and the
163 operational environment is known to support the
164 specified number of sockets.
165 Note also that the actual maximum number is normally a little
166 fewer than the specified value because
167 <span><strong class="command">named</strong></span> reserves some file descriptors
168 for its internal use.
172 <dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
175 to <em class="replaceable"><code>directory</code></em> after
176 processing the command line arguments, but before
177 reading the configuration file.
179 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
180 <h3 class="title">Warning</h3>
182 This option should be used in conjunction with the
183 <code class="option">-u</code> option, as chrooting a process
184 running as root doesn't enhance security on most
185 systems; the way <code class="function">chroot(2)</code> is
186 defined allows a process with root privileges to
187 escape a chroot jail.
191 <dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
194 to <em class="replaceable"><code>user</code></em> after completing
195 privileged operations, such as creating sockets that
196 listen on privileged ports.
198 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
199 <h3 class="title">Note</h3>
201 On Linux, <span><strong class="command">named</strong></span> uses the kernel's
202 capability mechanism to drop all root privileges
203 except the ability to <code class="function">bind(2)</code> to
205 privileged port and set process resource limits.
206 Unfortunately, this means that the <code class="option">-u</code>
207 option only works when <span><strong class="command">named</strong></span> is
209 on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or
210 later, since previous kernels did not allow privileges
211 to be retained after <code class="function">setuid(2)</code>.
215 <dt><span class="term">-v</span></dt>
217 Report the version number and exit.
219 <dt><span class="term">-V</span></dt>
221 Report the version number and build options, and exit.
223 <dt><span class="term">-x <em class="replaceable"><code>cache-file</code></em></span></dt>
226 Load data from <em class="replaceable"><code>cache-file</code></em> into the
227 cache of the default view.
229 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
230 <h3 class="title">Warning</h3>
232 This option must not be used. It is only of interest
233 to BIND 9 developers and may be removed or changed in a
240 <div class="refsect1" lang="en">
241 <a name="id2652594"></a><h2>SIGNALS</h2>
243 In routine operation, signals should not be used to control
244 the nameserver; <span><strong class="command">rndc</strong></span> should be used
247 <div class="variablelist"><dl>
248 <dt><span class="term">SIGHUP</span></dt>
250 Force a reload of the server.
252 <dt><span class="term">SIGINT, SIGTERM</span></dt>
254 Shut down the server.
258 The result of sending any other signals to the server is undefined.
261 <div class="refsect1" lang="en">
262 <a name="id2652644"></a><h2>CONFIGURATION</h2>
264 The <span><strong class="command">named</strong></span> configuration file is too complex
265 to describe in detail here. A complete description is provided
267 <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
270 <span><strong class="command">named</strong></span> inherits the <code class="function">umask</code>
271 (file creation mode mask) from the parent process. If files
272 created by <span><strong class="command">named</strong></span>, such as journal files,
273 need to have custom permissions, the <code class="function">umask</code>
274 should be set explicitly in the script used to start the
275 <span><strong class="command">named</strong></span> process.
278 <div class="refsect1" lang="en">
279 <a name="id2652693"></a><h2>FILES</h2>
280 <div class="variablelist"><dl>
281 <dt><span class="term"><code class="filename">/etc/named.conf</code></span></dt>
283 The default configuration file.
285 <dt><span class="term"><code class="filename">/var/run/named/named.pid</code></span></dt>
287 The default process-id file.
291 <div class="refsect1" lang="en">
292 <a name="id2659836"></a><h2>SEE ALSO</h2>
293 <p><em class="citetitle">RFC 1033</em>,
294 <em class="citetitle">RFC 1034</em>,
295 <em class="citetitle">RFC 1035</em>,
296 <span class="citerefentry"><span class="refentrytitle">named-checkconf</span>(8)</span>,
297 <span class="citerefentry"><span class="refentrytitle">named-checkzone</span>(8)</span>,
298 <span class="citerefentry"><span class="refentrytitle">rndc</span>(8)</span>,
299 <span class="citerefentry"><span class="refentrytitle">lwresd</span>(8)</span>,
300 <span class="citerefentry"><span class="refentrytitle">named.conf</span>(5)</span>,
301 <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
304 <div class="refsect1" lang="en">
305 <a name="id2659907"></a><h2>AUTHOR</h2>
306 <p><span class="corpauthor">Internet Systems Consortium</span>
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