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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>option</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">-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="id2642459"></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="id2642490"></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>option</code></em></span></dt>
119 Sets the default memory context options. Currently
120 the only supported option is
121 <em class="replaceable"><code>external</code></em>,
122 which causes the internal memory manager to be bypassed
123 in favor of system-provided memory allocation functions.
125 <dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
127 Turn on memory usage debugging flags. Possible flags are
128 <em class="replaceable"><code>usage</code></em>,
129 <em class="replaceable"><code>trace</code></em>,
130 <em class="replaceable"><code>record</code></em>,
131 <em class="replaceable"><code>size</code></em>, and
132 <em class="replaceable"><code>mctx</code></em>.
133 These correspond to the ISC_MEM_DEBUGXXXX flags described in
134 <code class="filename"><isc/mem.h></code>.
136 <dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
138 Create <em class="replaceable"><code>#cpus</code></em> worker threads
139 to take advantage of multiple CPUs. If not specified,
140 <span><strong class="command">named</strong></span> will try to determine the
141 number of CPUs present and create one thread per CPU.
142 If it is unable to determine the number of CPUs, a
143 single worker thread will be created.
145 <dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
147 Listen for queries on port <em class="replaceable"><code>port</code></em>. If not
148 specified, the default is port 53.
150 <dt><span class="term">-s</span></dt>
153 Write memory usage statistics to <code class="filename">stdout</code> on exit.
155 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
156 <h3 class="title">Note</h3>
158 This option is mainly of interest to BIND 9 developers
159 and may be removed or changed in a future release.
163 <dt><span class="term">-S <em class="replaceable"><code>#max-socks</code></em></span></dt>
166 Allow <span><strong class="command">named</strong></span> to use up to
167 <em class="replaceable"><code>#max-socks</code></em> sockets.
169 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
170 <h3 class="title">Warning</h3>
172 This option should be unnecessary for the vast majority
174 The use of this option could even be harmful because the
175 specified value may exceed the limitation of the
176 underlying system API.
177 It is therefore set only when the default configuration
178 causes exhaustion of file descriptors and the
179 operational environment is known to support the
180 specified number of sockets.
181 Note also that the actual maximum number is normally a little
182 fewer than the specified value because
183 <span><strong class="command">named</strong></span> reserves some file descriptors
184 for its internal use.
188 <dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
191 to <em class="replaceable"><code>directory</code></em> after
192 processing the command line arguments, but before
193 reading the configuration file.
195 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
196 <h3 class="title">Warning</h3>
198 This option should be used in conjunction with the
199 <code class="option">-u</code> option, as chrooting a process
200 running as root doesn't enhance security on most
201 systems; the way <code class="function">chroot(2)</code> is
202 defined allows a process with root privileges to
203 escape a chroot jail.
207 <dt><span class="term">-U <em class="replaceable"><code>#listeners</code></em></span></dt>
209 Use <em class="replaceable"><code>#listeners</code></em>
210 worker threads to listen for incoming UDP packets on each
211 address. If not specified, <span><strong class="command">named</strong></span> will
212 calculate a default value based on the number of detected
213 CPUs: 1 for 1 CPU, 2 for 2-4 CPUs, and the number of
214 detected CPUs divided by 2 for values higher than 4.
215 If <code class="option">-n</code> has been set to a higher value than
216 the number of detected CPUs, then <code class="option">-U</code> may
217 be increased as high as that value, but no higher.
219 <dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
222 to <em class="replaceable"><code>user</code></em> after completing
223 privileged operations, such as creating sockets that
224 listen on privileged ports.
226 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
227 <h3 class="title">Note</h3>
229 On Linux, <span><strong class="command">named</strong></span> uses the kernel's
230 capability mechanism to drop all root privileges
231 except the ability to <code class="function">bind(2)</code> to
233 privileged port and set process resource limits.
234 Unfortunately, this means that the <code class="option">-u</code>
235 option only works when <span><strong class="command">named</strong></span> is
237 on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or
238 later, since previous kernels did not allow privileges
239 to be retained after <code class="function">setuid(2)</code>.
243 <dt><span class="term">-v</span></dt>
245 Report the version number and exit.
247 <dt><span class="term">-V</span></dt>
249 Report the version number and build options, and exit.
251 <dt><span class="term">-x <em class="replaceable"><code>cache-file</code></em></span></dt>
254 Load data from <em class="replaceable"><code>cache-file</code></em> into the
255 cache of the default view.
257 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
258 <h3 class="title">Warning</h3>
260 This option must not be used. It is only of interest
261 to BIND 9 developers and may be removed or changed in a
268 <div class="refsect1" lang="en">
269 <a name="id2681466"></a><h2>SIGNALS</h2>
271 In routine operation, signals should not be used to control
272 the nameserver; <span><strong class="command">rndc</strong></span> should be used
275 <div class="variablelist"><dl>
276 <dt><span class="term">SIGHUP</span></dt>
278 Force a reload of the server.
280 <dt><span class="term">SIGINT, SIGTERM</span></dt>
282 Shut down the server.
286 The result of sending any other signals to the server is undefined.
289 <div class="refsect1" lang="en">
290 <a name="id2681585"></a><h2>CONFIGURATION</h2>
292 The <span><strong class="command">named</strong></span> configuration file is too complex
293 to describe in detail here. A complete description is provided
295 <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
298 <span><strong class="command">named</strong></span> inherits the <code class="function">umask</code>
299 (file creation mode mask) from the parent process. If files
300 created by <span><strong class="command">named</strong></span>, such as journal files,
301 need to have custom permissions, the <code class="function">umask</code>
302 should be set explicitly in the script used to start the
303 <span><strong class="command">named</strong></span> process.
306 <div class="refsect1" lang="en">
307 <a name="id2681634"></a><h2>FILES</h2>
308 <div class="variablelist"><dl>
309 <dt><span class="term"><code class="filename">/etc/named.conf</code></span></dt>
311 The default configuration file.
313 <dt><span class="term"><code class="filename">/var/run/named/named.pid</code></span></dt>
315 The default process-id file.
319 <div class="refsect1" lang="en">
320 <a name="id2681677"></a><h2>SEE ALSO</h2>
321 <p><em class="citetitle">RFC 1033</em>,
322 <em class="citetitle">RFC 1034</em>,
323 <em class="citetitle">RFC 1035</em>,
324 <span class="citerefentry"><span class="refentrytitle">named-checkconf</span>(8)</span>,
325 <span class="citerefentry"><span class="refentrytitle">named-checkzone</span>(8)</span>,
326 <span class="citerefentry"><span class="refentrytitle">rndc</span>(8)</span>,
327 <span class="citerefentry"><span class="refentrytitle">lwresd</span>(8)</span>,
328 <span class="citerefentry"><span class="refentrytitle">named.conf</span>(5)</span>,
329 <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
332 <div class="refsect1" lang="en">
333 <a name="id2681748"></a><h2>AUTHOR</h2>
334 <p><span class="corpauthor">Internet Systems Consortium</span>
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357 <p style="text-align: center;">BIND 9.9.8-P4 (Extended Support Version)</p>