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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?> | |
3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
4 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
5 | ||
6 | <!-- | |
7 | This file is part of systemd. | |
8 | ||
9 | Copyright 2010 Lennart Poettering | |
10 | ||
11 | systemd is free software; you can redistribute it and/or modify it | |
12 | under the terms of the GNU General Public License as published by | |
13 | the Free Software Foundation; either version 2 of the License, or | |
14 | (at your option) any later version. | |
15 | ||
16 | systemd is distributed in the hope that it will be useful, but | |
17 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | General Public License for more details. | |
20 | ||
21 | You should have received a copy of the GNU General Public License | |
22 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
23 | --> | |
24 | ||
25 | <refentry id="systemd.socket"> | |
26 | <refentryinfo> | |
27 | <title>systemd.socket</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>systemd.socket</refentrytitle> | |
42 | <manvolnum>5</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>systemd.socket</refname> | |
47 | <refpurpose>systemd socket configuration files</refpurpose> | |
48 | </refnamediv> | |
49 | ||
50 | <refsynopsisdiv> | |
51 | <para><filename>systemd.socket</filename></para> | |
52 | </refsynopsisdiv> | |
53 | ||
54 | <refsect1> | |
55 | <title>Description</title> | |
56 | ||
57 | <para>A unit configuration file whose name ends in .socket | |
58 | encodes information about an IPC or network socket or | |
59 | a file system FIFO controlled and supervised by systemd, | |
60 | for socket-based activation.</para> | |
61 | ||
62 | <para>This man page lists the configuration options | |
63 | specific to this unit type. See | |
64 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
65 | for the common options of all unit configuration | |
66 | files. The common configuration items are configured | |
67 | in the generic [Unit] and [Install] sections. The | |
cdb788e4 | 68 | socket specific configuration options are configured |
1f812fea LP |
69 | in the [Socket] section.</para> |
70 | ||
71 | <para>Additional options are listed in | |
72 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> | |
73 | ||
74 | <para>For each socket file a matching service file (see <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details) | |
75 | must exist, describing the service to start on | |
76 | incoming traffic on the socket. Depending on the | |
77 | setting of <option>Accept=</option> (see below) this | |
78 | must either be named like the socket unit, but with | |
79 | the suffix replaced; or it must be a template file | |
80 | named the same way. Example: a socket file | |
81 | <filename>foo.socket</filename> needs a matching | |
82 | service <filename>foo.service</filename> if | |
83 | <option>Accept=false</option> is set. If | |
84 | <option>Accept=true</option> is set a service template | |
85 | file <filename>foo@.service</filename> must exist from | |
86 | which services are instantiated for each incoming | |
87 | connection.</para> | |
88 | </refsect1> | |
89 | ||
90 | <refsect1> | |
91 | <title>Options</title> | |
92 | ||
93 | <para>Socket files must include a [Socket] section, | |
94 | which carries information about the socket or FIFO it | |
95 | supervises. A number of options that may be used in | |
96 | this section are shared with other unit types. These | |
97 | options are documented in | |
98 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The | |
99 | options specific to the [Socket] section of service | |
100 | units are the following:</para> | |
101 | ||
102 | <variablelist> | |
103 | <varlistentry> | |
104 | <term><varname>ListenStream=</varname></term> | |
105 | <term><varname>ListenDatagram=</varname></term> | |
106 | <term><varname>ListenSequentialPacket=</varname></term> | |
107 | <listitem><para>Specifies an address | |
108 | to listen on for a stream | |
109 | (SOCK_STREAM), datagram (SOCK_DGRAM) | |
110 | resp. sequential packet | |
111 | (SOCK_SEQPACKET) socket. The address | |
112 | can be written in various formats:</para> | |
113 | ||
114 | <para>If the address starts with a | |
115 | slash (/), it is read as file system | |
116 | socket in the AF_UNIX socket | |
117 | family.</para> | |
118 | ||
119 | <para>If the address starts with an | |
120 | ampersand (@) it is read as abstract | |
121 | namespace socket in the AF_UNIX | |
122 | family. The @ is replaced with a NUL | |
123 | character before binding. For details | |
124 | see | |
125 | <citerefentry><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> | |
126 | ||
127 | <para>If the address string is a | |
128 | single number it is read as port | |
129 | number to listen on for both IPv4 and | |
130 | IPv6.</para> | |
131 | ||
132 | <para>If the address string is a | |
133 | string in the format v.w.x.y:z it is | |
134 | read as IPv4 specifier for listening | |
135 | on an address v.w.x.y on a port | |
136 | z.</para> | |
137 | ||
138 | <para>If the address string is a | |
139 | string in the format [x]:y it is read | |
140 | as IPv6 address x on a port y.</para> | |
141 | ||
142 | <para>Note that SOCK_SEQPACKET | |
143 | (i.e. <varname>ListenSequentialPacket=</varname>) | |
144 | is only available for AF_UNIX | |
145 | sockets. SOCK_STREAM | |
146 | (i.e. <varname>ListenStream=</varname>) | |
147 | when used for IP sockets refers to TCP | |
148 | sockets, SOCK_DGRAM | |
149 | (i.e. <varname>ListenDatagram=</varname>) | |
150 | to UDP.</para> | |
151 | ||
152 | <para>These options may be specified | |
153 | more than once in which case incoming | |
154 | traffic on any of the sockets will trigger | |
155 | service activation, and all listed | |
156 | sockets will be passed to the service, | |
157 | regardless whether there is incoming | |
158 | traffic on them or not.</para> | |
159 | ||
160 | <para>If an IP address is used here it | |
161 | is often desirable to listen on it | |
162 | before the interface it is configured | |
163 | on is up and running, and even | |
164 | regardless whether it will be up and | |
165 | running ever at all. To deal with this it is | |
166 | recommended to set the | |
167 | <varname>FreeBind=</varname> option | |
168 | described below.</para></listitem> | |
169 | </varlistentry> | |
170 | ||
171 | <varlistentry> | |
172 | <term><varname>ListenFIFO=</varname></term> | |
173 | <listitem><para>Specifies a file | |
174 | system FIFO to listen on. This expects | |
175 | an absolute file system path as | |
176 | argument. Behaviour otherwise is very | |
177 | similar to the | |
178 | <varname>ListenDatagram=</varname> | |
179 | directive above.</para></listitem> | |
180 | </varlistentry> | |
181 | ||
182 | <varlistentry> | |
183 | <term><varname>BindIPv6Only=</varname></term> | |
184 | <listitem><para>Takes a one of | |
185 | <option>default</option>, | |
186 | <option>both</option> or | |
187 | <option>ipv6-only</option>. Controls | |
188 | the IPV6_V6ONLY socket option (see | |
189 | <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
190 | for details). If | |
191 | <option>both</option>, IPv6 sockets | |
192 | bound will be accessible via both IPv4 | |
193 | and IPv6. If | |
194 | <option>ipv6-only</option>, they will | |
195 | be accessible via IPv6 only. If | |
196 | <option>default</option> (which is the | |
197 | default, surprise!) the system wide | |
198 | default setting is used, as controlled | |
199 | by | |
200 | <filename>/proc/sys/net/ipv6/bindv6only</filename>.</para> | |
201 | </listitem> | |
202 | </varlistentry> | |
203 | ||
204 | <varlistentry> | |
205 | <term><varname>Backlog=</varname></term> | |
206 | <listitem><para>Takes an unsigned | |
207 | integer argument. Specifies the number | |
208 | of connections to queue that have not | |
209 | been accepted yet. This setting | |
210 | matters only for stream and sequential | |
211 | packet sockets. See | |
212 | <citerefentry><refentrytitle>listen</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
213 | for details. Defaults to SOMAXCONN | |
214 | (128).</para></listitem> | |
215 | </varlistentry> | |
216 | ||
217 | <varlistentry> | |
218 | <term><varname>BindToDevice=</varname></term> | |
219 | <listitem><para>Specifies a network | |
220 | interface name to bind this socket | |
221 | to. If set traffic will only be | |
222 | accepted from the specified network | |
223 | interfaces. This controls the | |
224 | SO_BINDTODEVICE socket option (see | |
225 | <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
226 | for details). If this option is used | |
227 | an automatic dependency from this | |
228 | socket unit on the network interface | |
229 | device unit | |
230 | (<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
231 | is created.</para></listitem> | |
232 | </varlistentry> | |
233 | ||
234 | <varlistentry> | |
235 | <term><varname>DirectoryMode=</varname></term> | |
236 | <listitem><para>If listening on a file | |
237 | system socket of FIFO the parent | |
238 | directories are automatically created | |
239 | if needed. This option specifies the | |
240 | file system access mode used when | |
241 | creating these directories. Defaults | |
242 | to 0755.</para></listitem> | |
243 | </varlistentry> | |
244 | ||
245 | <varlistentry> | |
246 | <term><varname>SocketMode=</varname></term> | |
247 | <listitem><para>If listening on a file | |
248 | system socket of FIFO this option | |
249 | specifies the file system access mode | |
250 | used when creating the file | |
251 | node. Defaults to | |
252 | 0666.</para></listitem> | |
253 | </varlistentry> | |
254 | ||
255 | <varlistentry> | |
256 | <term><varname>Accept=</varname></term> | |
257 | <listitem><para>Takes a boolean | |
258 | argument. If true a service instance | |
259 | is spawned for each incoming | |
260 | connection and only the connection | |
261 | socket is passed to it. If false all | |
262 | listening sockets themselves are | |
263 | passed to the started service unit, | |
264 | and only one service unit is spawned | |
265 | for all connections (also see | |
266 | above). This value is ignored for | |
267 | datagram sockets and FIFOs where | |
268 | unconditionally a single service unit | |
269 | handles all incoming traffic. Defaults | |
270 | to <option>false</option>. For | |
271 | performance reasons it is recommended | |
272 | to write new daemons only in a way | |
273 | that is suitable for | |
274 | <option>Accept=false</option>. This | |
275 | option is mostly useful to allow | |
276 | daemons designed for usage with | |
277 | <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
278 | to work unmodified with system socket | |
279 | activation.</para></listitem> | |
280 | </varlistentry> | |
281 | ||
282 | <varlistentry> | |
283 | <term><varname>MaxConnections=</varname></term> | |
284 | <listitem><para>The maximum number of | |
285 | connections to simultaneously run | |
286 | services instances for, when | |
287 | <option>Accept=true</option> is | |
288 | set. If more concurrent connections | |
289 | are coming in they will be refused, | |
290 | until at least one existing connection | |
291 | is terminated. This setting has no | |
292 | effect for sockets configured with | |
293 | <option>Accept=no</option> or datagram | |
294 | sockets. Defaults to | |
295 | 64.</para></listitem> | |
296 | </varlistentry> | |
297 | ||
298 | <varlistentry> | |
299 | <term><varname>KeepAlive=</varname></term> | |
300 | <listitem><para>Takes a boolean | |
301 | argument. If true, the TCP/IP stack | |
302 | will send a keep alive message after | |
303 | 2h (depending on the configuration of | |
304 | <filename>/proc/sys/net/ipv4/tcp_keepalive_time</filename>) | |
305 | for all TCP streams accepted on this | |
306 | socket. This controls the SO_KEEPALIVE | |
307 | socket option (see | |
308 | <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
309 | and the <ulink | |
310 | url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP | |
311 | Keepalive HOWTO</ulink> for details.) | |
312 | Defaults to | |
313 | <option>false</option>.</para></listitem> | |
314 | </varlistentry> | |
315 | ||
316 | <varlistentry> | |
317 | <term><varname>Priority=</varname></term> | |
318 | <listitem><para>Takes an integer | |
319 | argument controlling the priority for | |
320 | all traffic sent from this | |
321 | socket. This controls the SO_PRIORITY | |
322 | socket option (see | |
323 | <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
324 | for details.).</para></listitem> | |
325 | </varlistentry> | |
326 | ||
327 | <varlistentry> | |
328 | <term><varname>ReceiveBuffer=</varname></term> | |
329 | <term><varname>SendBuffer=</varname></term> | |
330 | <listitem><para>Takes an integer | |
331 | argument controlling the receive | |
332 | resp. send buffer sizes of this | |
333 | socket. This controls the SO_RCVBUF | |
334 | resp. SO_SNDBUF socket options (see | |
335 | <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
336 | for details.).</para></listitem> | |
337 | </varlistentry> | |
338 | ||
339 | <varlistentry> | |
340 | <term><varname>IPTOS=</varname></term> | |
341 | <listitem><para>Takes an integer | |
342 | argument controlling the IP | |
343 | Type-Of-Service field for packets | |
344 | generated from this socket. This | |
345 | controls the IP_TOS socket option (see | |
346 | <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
347 | for details.). Either a numeric string | |
348 | or one of <option>low-delay</option>, | |
349 | <option>throughput</option>, | |
350 | <option>reliability</option> or | |
351 | <option>low-cost</option> may be | |
352 | specified.</para></listitem> | |
353 | </varlistentry> | |
354 | ||
355 | <varlistentry> | |
356 | <term><varname>IPTTL=</varname></term> | |
357 | <listitem><para>Takes an integer | |
358 | argument controlling the IPv4 | |
359 | Time-To-Live/IPv6 Hop-Count field for | |
360 | packets generated from this | |
361 | socket. This sets the | |
362 | IP_TTL/IPV6_UNICAST_HOPS socket | |
363 | options (see | |
364 | <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
365 | and | |
366 | <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
367 | for details.)</para></listitem> | |
368 | </varlistentry> | |
369 | ||
370 | <varlistentry> | |
371 | <term><varname>Mark=</varname></term> | |
372 | <listitem><para>Takes an integer | |
373 | value. Controls the firewall mark of | |
374 | packets generated by this socket. This | |
375 | can be used in the firewall logic to | |
376 | filter packets from this socket. This | |
377 | sets the SO_MARK socket option. See | |
378 | <citerefentry><refentrytitle>iptables</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
379 | for details.</para></listitem> | |
380 | </varlistentry> | |
381 | ||
382 | <varlistentry> | |
383 | <term><varname>PipeSize=</varname></term> | |
384 | <listitem><para>Takes an integer | |
385 | value. Controls the pipe buffer size | |
386 | of FIFOs configured in this socket | |
387 | unit. See | |
388 | <citerefentry><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
389 | for details.</para></listitem> | |
390 | </varlistentry> | |
391 | ||
392 | <varlistentry> | |
393 | <term><varname>FreeBind=</varname></term> | |
394 | <listitem><para>Takes a boolean | |
395 | value. Controls whether the socket can | |
396 | be bound to non-local IP | |
397 | addresses. This is useful to configure | |
398 | sockets listening on specific IP | |
399 | addresses before those IP addresses | |
400 | are successfully configured on a | |
401 | network interface. This sets the | |
402 | IP_FREEBIND socket option. For | |
403 | robustness reasons it is recommended | |
404 | to use this option whenever you bind a | |
405 | socket to a specific IP | |
406 | address. Defaults to <option>false</option>.</para></listitem> | |
407 | </varlistentry> | |
408 | ||
1f812fea LP |
409 | <varlistentry> |
410 | <term><varname>ExecStartPre=</varname></term> | |
411 | <term><varname>ExecStartPost=</varname></term> | |
412 | <listitem><para>Takes a command line | |
413 | that is executed before (resp. after) | |
414 | the listening sockets/FIFOs are created and | |
415 | bound. The first token of the command | |
416 | line must be an absolute file name, | |
417 | then followed by arguments for the | |
418 | process. If specified more than once, | |
419 | all commands are executed one after | |
420 | the other, serially. Use of these | |
421 | settings is optional.</para></listitem> | |
422 | </varlistentry> | |
423 | ||
424 | <varlistentry> | |
425 | <term><varname>ExecStopPre=</varname></term> | |
426 | <term><varname>ExecStopPost=</varname></term> | |
427 | <listitem><para>Additional commands | |
428 | that are executed before (resp. after) | |
429 | the listening sockets/FIFOs are closed | |
430 | and removed. If specified more than | |
431 | once, all commands are executed one | |
432 | after the other, serially. Use of | |
433 | these settings is | |
434 | optional.</para></listitem> | |
435 | </varlistentry> | |
436 | ||
1f812fea LP |
437 | <varlistentry> |
438 | <term><varname>TimeoutSec=</varname></term> | |
439 | <listitem><para>Configures the time to | |
440 | wait for the commands specified in | |
441 | <varname>ExecStartPre=</varname>, | |
442 | <varname>ExecStartPost=</varname>, | |
443 | <varname>ExecStopPre=</varname> and | |
444 | <varname>ExecStopPost=</varname> to | |
445 | finish. If a comand does not exit | |
446 | within the configured time the socket | |
447 | will be considered failed and be shut | |
448 | down again. All commands still running | |
449 | will be terminated forcibly via | |
450 | SIGTERM, and after another delay of | |
451 | this time with SIGKILL. (See | |
cdb788e4 | 452 | <option>KillMode=</option> below.) |
1f812fea LP |
453 | Takes a unit-less value in seconds, or |
454 | a time span value such as "5min | |
455 | 20s". Pass 0 to disable the timeout | |
456 | logic. Defaults to | |
457 | 60s.</para></listitem> | |
458 | </varlistentry> | |
459 | ||
1f812fea LP |
460 | <varlistentry> |
461 | <term><varname>KillMode=</varname></term> | |
462 | <listitem><para>Specifies how | |
cdb788e4 | 463 | processes of this socket unit shall be |
1f812fea LP |
464 | killed. One of |
465 | <option>control-group</option>, | |
466 | <option>process-group</option>, | |
467 | <option>process</option>, | |
468 | <option>none</option>.</para> | |
469 | ||
470 | <para>This option is mostly equivalent | |
471 | to the <option>KillMode=</option> | |
472 | option of service files. See | |
473 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
474 | for details.</para></listitem> | |
475 | </varlistentry> | |
1f812fea LP |
476 | </variablelist> |
477 | </refsect1> | |
478 | ||
479 | <refsect1> | |
480 | <title>See Also</title> | |
481 | <para> | |
482 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
483 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
484 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
485 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
486 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
487 | </para> | |
488 | </refsect1> | |
489 | ||
490 | </refentry> |