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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">-E <em class="replaceable"><code>engine-name</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>#listeners</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="id2641988"></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="id2642019"></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">-E <em class="replaceable"><code>engine-name</code></em></span></dt>
102 Use a crypto hardware (OpenSSL engine) for the crypto operations
103 it supports, for instance re-signing with private keys from
104 a secure key store. When compiled with PKCS#11 support
105 <em class="replaceable"><code>engine-name</code></em>
106 defaults to pkcs11, the empty name resets it to no engine.
108 <dt><span class="term">-f</span></dt>
110 Run the server in the foreground (i.e. do not daemonize).
112 <dt><span class="term">-g</span></dt>
114 Run the server in the foreground and force all logging
115 to <code class="filename">stderr</code>.
117 <dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
119 Turn on memory usage debugging flags. Possible flags are
120 <em class="replaceable"><code>usage</code></em>,
121 <em class="replaceable"><code>trace</code></em>,
122 <em class="replaceable"><code>record</code></em>,
123 <em class="replaceable"><code>size</code></em>, and
124 <em class="replaceable"><code>mctx</code></em>.
125 These correspond to the ISC_MEM_DEBUGXXXX flags described in
126 <code class="filename"><isc/mem.h></code>.
128 <dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
130 Create <em class="replaceable"><code>#cpus</code></em> worker threads
131 to take advantage of multiple CPUs. If not specified,
132 <span><strong class="command">named</strong></span> will try to determine the
133 number of CPUs present and create one thread per CPU.
134 If it is unable to determine the number of CPUs, a
135 single worker thread will be created.
137 <dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
139 Listen for queries on port <em class="replaceable"><code>port</code></em>. If not
140 specified, the default is port 53.
142 <dt><span class="term">-s</span></dt>
145 Write memory usage statistics to <code class="filename">stdout</code> on exit.
147 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
148 <h3 class="title">Note</h3>
150 This option is mainly of interest to BIND 9 developers
151 and may be removed or changed in a future release.
155 <dt><span class="term">-S <em class="replaceable"><code>#max-socks</code></em></span></dt>
158 Allow <span><strong class="command">named</strong></span> to use up to
159 <em class="replaceable"><code>#max-socks</code></em> sockets.
161 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
162 <h3 class="title">Warning</h3>
164 This option should be unnecessary for the vast majority
166 The use of this option could even be harmful because the
167 specified value may exceed the limitation of the
168 underlying system API.
169 It is therefore set only when the default configuration
170 causes exhaustion of file descriptors and the
171 operational environment is known to support the
172 specified number of sockets.
173 Note also that the actual maximum number is normally a little
174 fewer than the specified value because
175 <span><strong class="command">named</strong></span> reserves some file descriptors
176 for its internal use.
180 <dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
183 to <em class="replaceable"><code>directory</code></em> after
184 processing the command line arguments, but before
185 reading the configuration file.
187 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
188 <h3 class="title">Warning</h3>
190 This option should be used in conjunction with the
191 <code class="option">-u</code> option, as chrooting a process
192 running as root doesn't enhance security on most
193 systems; the way <code class="function">chroot(2)</code> is
194 defined allows a process with root privileges to
195 escape a chroot jail.
199 <dt><span class="term">-U <em class="replaceable"><code>#listeners</code></em></span></dt>
201 Use <em class="replaceable"><code>#listeners</code></em>
202 worker threads to listen for incoming UDP packets on each
203 address. If not specified, <span><strong class="command">named</strong></span> will
204 calculate a default value based on the number of detected
205 CPUs: 1 for 1 CPU, 2 for 2-4 CPUs, and the number of
206 detected CPUs divided by 2 for values higher than 4.
207 If <code class="option">-n</code> has been set to a higher value than
208 the number of detected CPUs, then <code class="option">-U</code> may
209 be increased as high as that value, but no higher.
211 <dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
214 to <em class="replaceable"><code>user</code></em> after completing
215 privileged operations, such as creating sockets that
216 listen on privileged ports.
218 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
219 <h3 class="title">Note</h3>
221 On Linux, <span><strong class="command">named</strong></span> uses the kernel's
222 capability mechanism to drop all root privileges
223 except the ability to <code class="function">bind(2)</code> to
225 privileged port and set process resource limits.
226 Unfortunately, this means that the <code class="option">-u</code>
227 option only works when <span><strong class="command">named</strong></span> is
229 on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or
230 later, since previous kernels did not allow privileges
231 to be retained after <code class="function">setuid(2)</code>.
235 <dt><span class="term">-v</span></dt>
237 Report the version number and exit.
239 <dt><span class="term">-V</span></dt>
241 Report the version number and build options, and exit.
243 <dt><span class="term">-x <em class="replaceable"><code>cache-file</code></em></span></dt>
246 Load data from <em class="replaceable"><code>cache-file</code></em> into the
247 cache of the default view.
249 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
250 <h3 class="title">Warning</h3>
252 This option must not be used. It is only of interest
253 to BIND 9 developers and may be removed or changed in a
260 <div class="refsect1" lang="en">
261 <a name="id2677286"></a><h2>SIGNALS</h2>
263 In routine operation, signals should not be used to control
264 the nameserver; <span><strong class="command">rndc</strong></span> should be used
267 <div class="variablelist"><dl>
268 <dt><span class="term">SIGHUP</span></dt>
270 Force a reload of the server.
272 <dt><span class="term">SIGINT, SIGTERM</span></dt>
274 Shut down the server.
278 The result of sending any other signals to the server is undefined.
281 <div class="refsect1" lang="en">
282 <a name="id2677336"></a><h2>CONFIGURATION</h2>
284 The <span><strong class="command">named</strong></span> configuration file is too complex
285 to describe in detail here. A complete description is provided
287 <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
290 <span><strong class="command">named</strong></span> inherits the <code class="function">umask</code>
291 (file creation mode mask) from the parent process. If files
292 created by <span><strong class="command">named</strong></span>, such as journal files,
293 need to have custom permissions, the <code class="function">umask</code>
294 should be set explicitly in the script used to start the
295 <span><strong class="command">named</strong></span> process.
298 <div class="refsect1" lang="en">
299 <a name="id2677453"></a><h2>FILES</h2>
300 <div class="variablelist"><dl>
301 <dt><span class="term"><code class="filename">/etc/named.conf</code></span></dt>
303 The default configuration file.
305 <dt><span class="term"><code class="filename">/var/run/named/named.pid</code></span></dt>
307 The default process-id file.
311 <div class="refsect1" lang="en">
312 <a name="id2677497"></a><h2>SEE ALSO</h2>
313 <p><em class="citetitle">RFC 1033</em>,
314 <em class="citetitle">RFC 1034</em>,
315 <em class="citetitle">RFC 1035</em>,
316 <span class="citerefentry"><span class="refentrytitle">named-checkconf</span>(8)</span>,
317 <span class="citerefentry"><span class="refentrytitle">named-checkzone</span>(8)</span>,
318 <span class="citerefentry"><span class="refentrytitle">rndc</span>(8)</span>,
319 <span class="citerefentry"><span class="refentrytitle">lwresd</span>(8)</span>,
320 <span class="citerefentry"><span class="refentrytitle">named.conf</span>(5)</span>,
321 <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
324 <div class="refsect1" lang="en">
325 <a name="id2677568"></a><h2>AUTHOR</h2>
326 <p><span class="corpauthor">Internet Systems Consortium</span>
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349 <p style="text-align: center;">BIND Version 9.9</p>