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514094f9 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
0307f791 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
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5 | |
6 | <refentry id="systemd.socket"> | |
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7 | <refentryinfo> |
8 | <title>systemd.socket</title> | |
9 | <productname>systemd</productname> | |
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10 | </refentryinfo> |
11 | ||
12 | <refmeta> | |
13 | <refentrytitle>systemd.socket</refentrytitle> | |
14 | <manvolnum>5</manvolnum> | |
15 | </refmeta> | |
16 | ||
17 | <refnamediv> | |
18 | <refname>systemd.socket</refname> | |
19 | <refpurpose>Socket unit configuration</refpurpose> | |
20 | </refnamediv> | |
21 | ||
22 | <refsynopsisdiv> | |
23 | <para><filename><replaceable>socket</replaceable>.socket</filename></para> | |
24 | </refsynopsisdiv> | |
25 | ||
26 | <refsect1> | |
27 | <title>Description</title> | |
28 | ||
29 | <para>A unit configuration file whose name ends in | |
30 | <literal>.socket</literal> encodes information about an IPC or | |
31 | network socket or a file system FIFO controlled and supervised by | |
32 | systemd, for socket-based activation.</para> | |
33 | ||
34 | <para>This man page lists the configuration options specific to | |
35 | this unit type. See | |
36 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
37 | for the common options of all unit configuration files. The common | |
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38 | configuration items are configured in the generic [Unit] and |
39 | [Install] sections. The socket specific configuration options are | |
40 | configured in the [Socket] section.</para> | |
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41 | |
42 | <para>Additional options are listed in | |
43 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
44 | which define the execution environment the | |
45 | <option>ExecStartPre=</option>, <option>ExecStartPost=</option>, | |
46 | <option>ExecStopPre=</option> and <option>ExecStopPost=</option> | |
47 | commands are executed in, and in | |
48 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
49 | which define the way the processes are terminated, and in | |
50 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
51 | which configure resource control settings for the processes of the | |
52 | socket.</para> | |
53 | ||
847af199 | 54 | <para>For each socket unit, a matching service unit must exist, |
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55 | describing the service to start on incoming traffic on the socket |
56 | (see | |
57 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
847af199 | 58 | for more information about .service units). The name of the |
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59 | .service unit is by default the same as the name of the .socket |
60 | unit, but can be altered with the <option>Service=</option> option | |
61 | described below. Depending on the setting of the | |
62 | <option>Accept=</option> option described below, this .service | |
63 | unit must either be named like the .socket unit, but with the | |
64 | suffix replaced, unless overridden with <option>Service=</option>; | |
65 | or it must be a template unit named the same way. Example: a | |
66 | socket file <filename>foo.socket</filename> needs a matching | |
67 | service <filename>foo.service</filename> if | |
964c4eda | 68 | <option>Accept=no</option> is set. If |
847af199 | 69 | <option>Accept=yes</option> is set, a service template |
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70 | <filename>foo@.service</filename> must exist from which services |
71 | are instantiated for each incoming connection.</para> | |
72 | ||
45f09f93 | 73 | <para>No implicit <varname>WantedBy=</varname> or |
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74 | <varname>RequiredBy=</varname> dependency from the socket to the |
75 | service is added. This means that the service may be started | |
76 | without the socket, in which case it must be able to open sockets | |
77 | by itself. To prevent this, an explicit | |
78 | <varname>Requires=</varname> dependency may be added.</para> | |
79 | ||
80 | <para>Socket units may be used to implement on-demand starting of | |
81 | services, as well as parallelized starting of services. See the | |
82 | blog stories linked at the end for an introduction.</para> | |
83 | ||
84 | <para>Note that the daemon software configured for socket | |
85 | activation with socket units needs to be able to accept sockets | |
86 | from systemd, either via systemd's native socket passing interface | |
87 | (see | |
88 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
89 | for details) or via the traditional | |
b5c7d097 | 90 | <citerefentry project='freebsd'><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>-style |
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91 | socket passing (i.e. sockets passed in via standard input and |
92 | output, using <varname>StandardInput=socket</varname> in the | |
93 | service file).</para> | |
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94 | |
95 | <para>All network sockets allocated through <filename>.socket</filename> units are allocated in the host's network | |
96 | namespace (see <citerefentry | |
97 | project='man-pages'><refentrytitle>network_namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>). This | |
98 | does not mean however that the service activated by a configured socket unit has to be part of the host's network | |
99 | namespace as well. It is supported and even good practice to run services in their own network namespace (for | |
100 | example through <varname>PrivateNetwork=</varname>, see | |
101 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>), receiving only | |
102 | the sockets configured through socket-activation from the host's namespace. In such a set-up communication within | |
103 | the host's network namespace is only permitted through the activation sockets passed in while all sockets allocated | |
104 | from the service code itself will be associated with the service's own namespace, and thus possibly subject to a a | |
105 | much more restrictive configuration.</para> | |
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106 | </refsect1> |
107 | ||
c129bd5d | 108 | <refsect1> |
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109 | <title>Automatic Dependencies</title> |
110 | ||
111 | <refsect2> | |
112 | <title>Implicit Dependencies</title> | |
113 | ||
114 | <para>The following dependencies are implicitly added:</para> | |
115 | ||
116 | <itemizedlist> | |
117 | <listitem><para>Socket units automatically gain a <varname>Before=</varname> | |
118 | dependency on the service units they activate.</para></listitem> | |
119 | ||
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120 | <listitem><para>Socket units referring to file system paths (such as <constant>AF_UNIX</constant> |
121 | sockets or FIFOs) implicitly gain <varname>Requires=</varname> and <varname>After=</varname> | |
122 | dependencies on all mount units necessary to access those paths.</para></listitem> | |
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123 | |
124 | <listitem><para>Socket units using the <varname>BindToDevice=</varname> | |
125 | setting automatically gain a <varname>BindsTo=</varname> and | |
126 | <varname>After=</varname> dependency on the device unit | |
127 | encapsulating the specified network interface.</para></listitem> | |
128 | </itemizedlist> | |
129 | ||
130 | <para>Additional implicit dependencies may be added as result of | |
131 | execution and resource control parameters as documented in | |
132 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
133 | and | |
134 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> | |
135 | </refsect2> | |
136 | ||
137 | <refsect2> | |
138 | <title>Default Dependencies</title> | |
139 | ||
140 | <para>The following dependencies are added unless | |
141 | <varname>DefaultDependencies=no</varname> is set:</para> | |
142 | ||
143 | <itemizedlist> | |
144 | <listitem><para>Socket units automatically gain a | |
145 | <varname>Before=</varname> dependency on | |
146 | <filename>sockets.target</filename>.</para></listitem> | |
147 | ||
148 | <listitem><para>Socket units automatically gain a pair of | |
149 | <varname>After=</varname> and <varname>Requires=</varname> | |
150 | dependency on <filename>sysinit.target</filename>, and a pair of | |
151 | <varname>Before=</varname> and <varname>Conflicts=</varname> | |
152 | dependencies on <filename>shutdown.target</filename>. These | |
153 | dependencies ensure that the socket unit is started before normal | |
154 | services at boot, and is stopped on shutdown. Only sockets | |
155 | involved with early boot or late system shutdown should disable | |
156 | <varname>DefaultDependencies=</varname> option.</para></listitem> | |
157 | </itemizedlist> | |
158 | </refsect2> | |
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159 | </refsect1> |
160 | ||
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161 | <refsect1> |
162 | <title>Options</title> | |
163 | ||
164 | <para>Socket files must include a [Socket] section, which carries | |
165 | information about the socket or FIFO it supervises. A number of | |
166 | options that may be used in this section are shared with other | |
167 | unit types. These options are documented in | |
168 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
169 | and | |
170 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
171 | The options specific to the [Socket] section of socket units are | |
172 | the following:</para> | |
173 | ||
174 | <variablelist class='unit-directives'> | |
175 | <varlistentry> | |
176 | <term><varname>ListenStream=</varname></term> | |
177 | <term><varname>ListenDatagram=</varname></term> | |
178 | <term><varname>ListenSequentialPacket=</varname></term> | |
179 | <listitem><para>Specifies an address to listen on for a stream | |
180 | (<constant>SOCK_STREAM</constant>), datagram | |
181 | (<constant>SOCK_DGRAM</constant>), or sequential packet | |
182 | (<constant>SOCK_SEQPACKET</constant>) socket, respectively. | |
183 | The address can be written in various formats:</para> | |
184 | ||
185 | <para>If the address starts with a slash | |
186 | (<literal>/</literal>), it is read as file system socket in | |
187 | the <constant>AF_UNIX</constant> socket family.</para> | |
188 | ||
189 | <para>If the address starts with an at symbol | |
190 | (<literal>@</literal>), it is read as abstract namespace | |
191 | socket in the <constant>AF_UNIX</constant> family. The | |
192 | <literal>@</literal> is replaced with a | |
193 | <constant>NUL</constant> character before binding. For | |
194 | details, see | |
195 | <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> | |
196 | ||
197 | <para>If the address string is a single number, it is read as | |
198 | port number to listen on via IPv6. Depending on the value of | |
199 | <varname>BindIPv6Only=</varname> (see below) this might result | |
200 | in the service being available via both IPv6 and IPv4 | |
201 | (default) or just via IPv6. | |
202 | </para> | |
203 | ||
204 | <para>If the address string is a string in the format | |
205 | v.w.x.y:z, it is read as IPv4 specifier for listening on an | |
206 | address v.w.x.y on a port z.</para> | |
207 | ||
208 | <para>If the address string is a string in the format [x]:y, | |
209 | it is read as IPv6 address x on a port y. Note that this might | |
210 | make the service available via IPv4, too, depending on the | |
211 | <varname>BindIPv6Only=</varname> setting (see below). | |
212 | </para> | |
213 | ||
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214 | <para>If the address string is a string in the format |
215 | <literal>vsock:x:y</literal>, it is read as CID <literal>x</literal> on | |
216 | a port <literal>y</literal> address in the | |
217 | <constant>AF_VSOCK</constant> family. The CID is a unique 32-bit | |
218 | integer identifier in <constant>AF_VSOCK</constant> analogous to an IP | |
219 | address. Specifying the CID is optional, and may be set to the empty | |
220 | string.</para> | |
221 | ||
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222 | <para>Note that <constant>SOCK_SEQPACKET</constant> (i.e. |
223 | <varname>ListenSequentialPacket=</varname>) is only available | |
224 | for <constant>AF_UNIX</constant> sockets. | |
225 | <constant>SOCK_STREAM</constant> (i.e. | |
226 | <varname>ListenStream=</varname>) when used for IP sockets | |
227 | refers to TCP sockets, <constant>SOCK_DGRAM</constant> (i.e. | |
228 | <varname>ListenDatagram=</varname>) to UDP.</para> | |
229 | ||
b938cb90 | 230 | <para>These options may be specified more than once, in which |
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231 | case incoming traffic on any of the sockets will trigger |
232 | service activation, and all listed sockets will be passed to | |
233 | the service, regardless of whether there is incoming traffic | |
234 | on them or not. If the empty string is assigned to any of | |
235 | these options, the list of addresses to listen on is reset, | |
236 | all prior uses of any of these options will have no | |
237 | effect.</para> | |
238 | ||
239 | <para>It is also possible to have more than one socket unit | |
240 | for the same service when using <varname>Service=</varname>, | |
241 | and the service will receive all the sockets configured in all | |
242 | the socket units. Sockets configured in one unit are passed in | |
243 | the order of configuration, but no ordering between socket | |
244 | units is specified.</para> | |
245 | ||
246 | <para>If an IP address is used here, it is often desirable to | |
247 | listen on it before the interface it is configured on is up | |
248 | and running, and even regardless of whether it will be up and | |
249 | running at any point. To deal with this, it is recommended to | |
250 | set the <varname>FreeBind=</varname> option described | |
251 | below.</para></listitem> | |
252 | </varlistentry> | |
253 | ||
254 | <varlistentry> | |
255 | <term><varname>ListenFIFO=</varname></term> | |
256 | <listitem><para>Specifies a file system FIFO to listen on. | |
257 | This expects an absolute file system path as argument. | |
258 | Behavior otherwise is very similar to the | |
259 | <varname>ListenDatagram=</varname> directive | |
260 | above.</para></listitem> | |
261 | </varlistentry> | |
262 | ||
263 | <varlistentry> | |
264 | <term><varname>ListenSpecial=</varname></term> | |
265 | <listitem><para>Specifies a special file in the file system to | |
266 | listen on. This expects an absolute file system path as | |
267 | argument. Behavior otherwise is very similar to the | |
268 | <varname>ListenFIFO=</varname> directive above. Use this to | |
269 | open character device nodes as well as special files in | |
270 | <filename>/proc</filename> and | |
271 | <filename>/sys</filename>.</para></listitem> | |
272 | </varlistentry> | |
273 | ||
274 | <varlistentry> | |
275 | <term><varname>ListenNetlink=</varname></term> | |
276 | <listitem><para>Specifies a Netlink family to create a socket | |
277 | for to listen on. This expects a short string referring to the | |
278 | <constant>AF_NETLINK</constant> family name (such as | |
279 | <varname>audit</varname> or <varname>kobject-uevent</varname>) | |
280 | as argument, optionally suffixed by a whitespace followed by a | |
281 | multicast group integer. Behavior otherwise is very similar to | |
282 | the <varname>ListenDatagram=</varname> directive | |
283 | above.</para></listitem> | |
284 | </varlistentry> | |
285 | ||
286 | <varlistentry> | |
287 | <term><varname>ListenMessageQueue=</varname></term> | |
288 | <listitem><para>Specifies a POSIX message queue name to listen | |
289 | on. This expects a valid message queue name (i.e. beginning | |
290 | with /). Behavior otherwise is very similar to the | |
291 | <varname>ListenFIFO=</varname> directive above. On Linux | |
292 | message queue descriptors are actually file descriptors and | |
293 | can be inherited between processes.</para></listitem> | |
294 | </varlistentry> | |
295 | ||
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296 | <varlistentry> |
297 | <term><varname>ListenUSBFunction=</varname></term> | |
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298 | <listitem><para>Specifies a <ulink |
299 | url="https://www.kernel.org/doc/Documentation/usb/functionfs.txt">USB | |
00bb64ec | 300 | FunctionFS</ulink> endpoints location to listen on, for |
3d314510 | 301 | implementation of USB gadget functions. This expects an |
e9dd6984 | 302 | absolute file system path of FunctionFS mount point as the argument. |
00bb64ec | 303 | Behavior otherwise is very similar to the <varname>ListenFIFO=</varname> |
a8eaaee7 | 304 | directive above. Use this to open the FunctionFS endpoint |
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305 | <filename>ep0</filename>. When using this option, the |
306 | activated service has to have the | |
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307 | <varname>USBFunctionDescriptors=</varname> and |
308 | <varname>USBFunctionStrings=</varname> options set. | |
81eb21b9 | 309 | </para></listitem> |
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310 | </varlistentry> |
311 | ||
74bb646e SS |
312 | <varlistentry> |
313 | <term><varname>SocketProtocol=</varname></term> | |
a7c64e14 | 314 | <listitem><para>Takes one of <option>udplite</option> |
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315 | or <option>sctp</option>. The socket will use the UDP-Lite |
316 | (<constant>IPPROTO_UDPLITE</constant>) or SCTP | |
317 | (<constant>IPPROTO_SCTP</constant>) protocol, respectively.</para> | |
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318 | </listitem> |
319 | </varlistentry> | |
320 | ||
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321 | <varlistentry> |
322 | <term><varname>BindIPv6Only=</varname></term> | |
a7c64e14 | 323 | <listitem><para>Takes one of <option>default</option>, |
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324 | <option>both</option> or <option>ipv6-only</option>. Controls |
325 | the IPV6_V6ONLY socket option (see | |
3ba3a79d | 326 | <citerefentry project='die-net'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
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327 | for details). If <option>both</option>, IPv6 sockets bound |
328 | will be accessible via both IPv4 and IPv6. If | |
329 | <option>ipv6-only</option>, they will be accessible via IPv6 | |
330 | only. If <option>default</option> (which is the default, | |
331 | surprise!), the system wide default setting is used, as | |
332 | controlled by | |
333 | <filename>/proc/sys/net/ipv6/bindv6only</filename>, which in | |
334 | turn defaults to the equivalent of | |
335 | <option>both</option>.</para> | |
336 | </listitem> | |
337 | </varlistentry> | |
338 | ||
339 | <varlistentry> | |
340 | <term><varname>Backlog=</varname></term> | |
341 | <listitem><para>Takes an unsigned integer argument. Specifies | |
342 | the number of connections to queue that have not been accepted | |
343 | yet. This setting matters only for stream and sequential | |
344 | packet sockets. See | |
345 | <citerefentry><refentrytitle>listen</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
346 | for details. Defaults to SOMAXCONN (128).</para></listitem> | |
347 | </varlistentry> | |
348 | ||
349 | <varlistentry> | |
350 | <term><varname>BindToDevice=</varname></term> | |
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351 | <listitem><para>Specifies a network interface name to bind this socket to. If set, traffic will only |
352 | be accepted from the specified network interfaces. This controls the | |
353 | <constant>SO_BINDTODEVICE</constant> socket option (see <citerefentry | |
354 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
355 | details). If this option is used, an implicit dependency from this socket unit on the network | |
356 | interface device unit is created | |
357 | (see <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
358 | Note that setting this parameter might result in additional dependencies to be added to the unit (see | |
c129bd5d | 359 | above).</para></listitem> |
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360 | </varlistentry> |
361 | ||
362 | <varlistentry> | |
363 | <term><varname>SocketUser=</varname></term> | |
364 | <term><varname>SocketGroup=</varname></term> | |
365 | ||
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366 | <listitem><para>Takes a UNIX user/group name. When specified, all <constant>AF_UNIX</constant> |
367 | sockets and FIFO nodes in the file system are owned by the specified user and group. If unset (the | |
368 | default), the nodes are owned by the root user/group (if run in system context) or the invoking | |
369 | user/group (if run in user context). If only a user is specified but no group, then the group is | |
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370 | derived from the user's default group.</para></listitem> |
371 | </varlistentry> | |
372 | ||
373 | <varlistentry> | |
374 | <term><varname>SocketMode=</varname></term> | |
375 | <listitem><para>If listening on a file system socket or FIFO, | |
376 | this option specifies the file system access mode used when | |
377 | creating the file node. Takes an access mode in octal | |
378 | notation. Defaults to 0666.</para></listitem> | |
379 | </varlistentry> | |
380 | ||
381 | <varlistentry> | |
382 | <term><varname>DirectoryMode=</varname></term> | |
383 | <listitem><para>If listening on a file system socket or FIFO, | |
384 | the parent directories are automatically created if needed. | |
385 | This option specifies the file system access mode used when | |
386 | creating these directories. Takes an access mode in octal | |
387 | notation. Defaults to 0755.</para></listitem> | |
388 | </varlistentry> | |
389 | ||
390 | <varlistentry> | |
391 | <term><varname>Accept=</varname></term> | |
392 | <listitem><para>Takes a boolean argument. If true, a service | |
393 | instance is spawned for each incoming connection and only the | |
394 | connection socket is passed to it. If false, all listening | |
395 | sockets themselves are passed to the started service unit, and | |
396 | only one service unit is spawned for all connections (also see | |
397 | above). This value is ignored for datagram sockets and FIFOs | |
398 | where a single service unit unconditionally handles all | |
399 | incoming traffic. Defaults to <option>false</option>. For | |
400 | performance reasons, it is recommended to write new daemons | |
401 | only in a way that is suitable for | |
964c4eda | 402 | <option>Accept=no</option>. A daemon listening on an |
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403 | <constant>AF_UNIX</constant> socket may, but does not need to, |
404 | call | |
405 | <citerefentry><refentrytitle>close</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
406 | on the received socket before exiting. However, it must not | |
407 | unlink the socket from a file system. It should not invoke | |
408 | <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
964c4eda | 409 | on sockets it got with <varname>Accept=no</varname>, but it |
798d3a52 | 410 | may do so for sockets it got with |
964c4eda LP |
411 | <varname>Accept=yes</varname> set. Setting |
412 | <varname>Accept=yes</varname> is mostly useful to allow | |
798d3a52 | 413 | daemons designed for usage with |
b5c7d097 | 414 | <citerefentry project='freebsd'><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
798d3a52 | 415 | to work unmodified with systemd socket |
3b1c5241 SL |
416 | activation.</para> |
417 | ||
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418 | <para>For IPv4 and IPv6 connections, the <varname>REMOTE_ADDR</varname> environment variable will |
419 | contain the remote IP address, and <varname>REMOTE_PORT</varname> will contain the remote port. This | |
420 | is the same as the format used by CGI. For <constant>SOCK_RAW</constant>, the port is the IP | |
421 | protocol.</para></listitem> | |
798d3a52 ZJS |
422 | </varlistentry> |
423 | ||
55301ec0 LP |
424 | <varlistentry> |
425 | <term><varname>Writable=</varname></term> | |
426 | <listitem><para>Takes a boolean argument. May only be used in | |
427 | conjunction with <varname>ListenSpecial=</varname>. If true, | |
428 | the specified special file is opened in read-write mode, if | |
b938cb90 | 429 | false, in read-only mode. Defaults to false.</para></listitem> |
55301ec0 LP |
430 | </varlistentry> |
431 | ||
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432 | <varlistentry> |
433 | <term><varname>MaxConnections=</varname></term> | |
434 | <listitem><para>The maximum number of connections to | |
435 | simultaneously run services instances for, when | |
964c4eda | 436 | <option>Accept=yes</option> is set. If more concurrent |
798d3a52 ZJS |
437 | connections are coming in, they will be refused until at least |
438 | one existing connection is terminated. This setting has no | |
439 | effect on sockets configured with | |
964c4eda | 440 | <option>Accept=no</option> or datagram sockets. Defaults to |
798d3a52 ZJS |
441 | 64.</para></listitem> |
442 | </varlistentry> | |
443 | ||
444 | <varlistentry> | |
9d565427 SS |
445 | <term><varname>MaxConnectionsPerSource=</varname></term> |
446 | <listitem><para>The maximum number of connections for a service per source IP address. | |
cfaf4b75 | 447 | This is very similar to the <varname>MaxConnections=</varname> directive |
9d565427 SS |
448 | above. Disabled by default.</para> |
449 | </listitem> | |
450 | </varlistentry> | |
451 | ||
452 | <varlistentry> | |
798d3a52 | 453 | <term><varname>KeepAlive=</varname></term> |
e9dd6984 ZJS |
454 | <listitem><para>Takes a boolean argument. If true, the TCP/IP stack will send a keep alive message |
455 | after 2h (depending on the configuration of | |
456 | <filename>/proc/sys/net/ipv4/tcp_keepalive_time</filename>) for all TCP streams accepted on this | |
457 | socket. This controls the <constant>SO_KEEPALIVE</constant> socket option (see <citerefentry | |
458 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> and | |
459 | the <ulink url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP Keepalive | |
460 | HOWTO</ulink> for details.) Defaults to <option>false</option>.</para></listitem> | |
798d3a52 ZJS |
461 | </varlistentry> |
462 | ||
463 | <varlistentry> | |
464 | <term><varname>KeepAliveTimeSec=</varname></term> | |
b938cb90 | 465 | <listitem><para>Takes time (in seconds) as argument. The connection needs to remain |
798d3a52 ZJS |
466 | idle before TCP starts sending keepalive probes. This controls the TCP_KEEPIDLE |
467 | socket option (see | |
3ba3a79d | 468 | <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
798d3a52 ZJS |
469 | and the <ulink |
470 | url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP | |
471 | Keepalive HOWTO</ulink> for details.) | |
472 | Defaults value is 7200 seconds (2 hours).</para></listitem> | |
473 | </varlistentry> | |
474 | ||
475 | <varlistentry> | |
476 | <term><varname>KeepAliveIntervalSec=</varname></term> | |
e9dd6984 ZJS |
477 | <listitem><para>Takes time (in seconds) as argument between individual keepalive probes, if the |
478 | socket option <constant>SO_KEEPALIVE</constant> has been set on this socket. This controls the | |
479 | <constant>TCP_KEEPINTVL</constant> socket option (see <citerefentry | |
480 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> and | |
481 | the <ulink url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP Keepalive | |
482 | HOWTO</ulink> for details.) Defaults value is 75 seconds.</para></listitem> | |
798d3a52 ZJS |
483 | </varlistentry> |
484 | ||
485 | <varlistentry> | |
486 | <term><varname>KeepAliveProbes=</varname></term> | |
7ca41557 | 487 | <listitem><para>Takes an integer as argument. It is the number of |
798d3a52 ZJS |
488 | unacknowledged probes to send before considering the |
489 | connection dead and notifying the application layer. This | |
490 | controls the TCP_KEEPCNT socket option (see | |
3ba3a79d | 491 | <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
798d3a52 ZJS |
492 | and the <ulink |
493 | url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP | |
494 | Keepalive HOWTO</ulink> for details.) Defaults value is | |
495 | 9.</para></listitem> | |
496 | </varlistentry> | |
497 | ||
498 | <varlistentry> | |
499 | <term><varname>NoDelay=</varname></term> | |
500 | <listitem><para>Takes a boolean argument. TCP Nagle's | |
501 | algorithm works by combining a number of small outgoing | |
502 | messages, and sending them all at once. This controls the | |
503 | TCP_NODELAY socket option (see | |
e9dd6984 | 504 | <citerefentry project='die-net'><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>). |
798d3a52 ZJS |
505 | Defaults to <option>false</option>.</para></listitem> |
506 | </varlistentry> | |
507 | ||
508 | <varlistentry> | |
509 | <term><varname>Priority=</varname></term> | |
e9dd6984 ZJS |
510 | <listitem><para>Takes an integer argument controlling the priority for all traffic sent from this |
511 | socket. This controls the <constant>SO_PRIORITY</constant> socket option (see <citerefentry | |
512 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
513 | details.).</para></listitem> | |
798d3a52 ZJS |
514 | </varlistentry> |
515 | ||
516 | <varlistentry> | |
517 | <term><varname>DeferAcceptSec=</varname></term> | |
518 | ||
519 | <listitem><para>Takes time (in seconds) as argument. If set, | |
520 | the listening process will be awakened only when data arrives | |
521 | on the socket, and not immediately when connection is | |
522 | established. When this option is set, the | |
523 | <constant>TCP_DEFER_ACCEPT</constant> socket option will be | |
524 | used (see | |
3ba3a79d | 525 | <citerefentry project='die-net'><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>), |
798d3a52 ZJS |
526 | and the kernel will ignore initial ACK packets without any |
527 | data. The argument specifies the approximate amount of time | |
528 | the kernel should wait for incoming data before falling back | |
2dd67817 | 529 | to the normal behavior of honoring empty ACK packets. This |
798d3a52 ZJS |
530 | option is beneficial for protocols where the client sends the |
531 | data first (e.g. HTTP, in contrast to SMTP), because the | |
532 | server process will not be woken up unnecessarily before it | |
533 | can take any action. | |
534 | </para> | |
535 | ||
536 | <para>If the client also uses the | |
537 | <constant>TCP_DEFER_ACCEPT</constant> option, the latency of | |
538 | the initial connection may be reduced, because the kernel will | |
539 | send data in the final packet establishing the connection (the | |
540 | third packet in the "three-way handshake").</para> | |
541 | ||
542 | <para>Disabled by default.</para> | |
543 | </listitem> | |
544 | </varlistentry> | |
545 | ||
546 | <varlistentry> | |
547 | <term><varname>ReceiveBuffer=</varname></term> | |
548 | <term><varname>SendBuffer=</varname></term> | |
e9dd6984 ZJS |
549 | <listitem><para>Takes an integer argument controlling the receive or send buffer sizes of this |
550 | socket, respectively. This controls the <constant>SO_RCVBUF</constant> and | |
551 | <constant>SO_SNDBUF</constant> socket options (see <citerefentry | |
552 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
553 | details.). The usual suffixes K, M, G are supported and are understood to the base of | |
554 | 1024.</para></listitem> | |
798d3a52 ZJS |
555 | </varlistentry> |
556 | ||
557 | <varlistentry> | |
558 | <term><varname>IPTOS=</varname></term> | |
559 | <listitem><para>Takes an integer argument controlling the IP | |
560 | Type-Of-Service field for packets generated from this socket. | |
561 | This controls the IP_TOS socket option (see | |
3ba3a79d | 562 | <citerefentry project='die-net'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
798d3a52 ZJS |
563 | for details.). Either a numeric string or one of |
564 | <option>low-delay</option>, <option>throughput</option>, | |
565 | <option>reliability</option> or <option>low-cost</option> may | |
566 | be specified.</para></listitem> | |
567 | </varlistentry> | |
568 | ||
569 | <varlistentry> | |
570 | <term><varname>IPTTL=</varname></term> | |
571 | <listitem><para>Takes an integer argument controlling the IPv4 | |
572 | Time-To-Live/IPv6 Hop-Count field for packets generated from | |
573 | this socket. This sets the IP_TTL/IPV6_UNICAST_HOPS socket | |
574 | options (see | |
3ba3a79d | 575 | <citerefentry project='die-net'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
798d3a52 | 576 | and |
3ba3a79d | 577 | <citerefentry project='die-net'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
798d3a52 ZJS |
578 | for details.)</para></listitem> |
579 | </varlistentry> | |
580 | ||
581 | <varlistentry> | |
582 | <term><varname>Mark=</varname></term> | |
e9dd6984 ZJS |
583 | <listitem><para>Takes an integer value. Controls the firewall mark of packets generated by this |
584 | socket. This can be used in the firewall logic to filter packets from this socket. This sets the | |
585 | <constant>SO_MARK</constant> socket option. See <citerefentry | |
586 | project='die-net'><refentrytitle>iptables</refentrytitle><manvolnum>8</manvolnum></citerefentry> for | |
587 | details.</para></listitem> | |
798d3a52 ZJS |
588 | </varlistentry> |
589 | ||
590 | <varlistentry> | |
591 | <term><varname>ReusePort=</varname></term> | |
e9dd6984 ZJS |
592 | <listitem><para>Takes a boolean value. If true, allows multiple |
593 | <citerefentry><refentrytitle>bind</refentrytitle><manvolnum>2</manvolnum></citerefentry>s to this TCP | |
594 | or UDP port. This controls the <constant>SO_REUSEPORT</constant> socket option. See <citerefentry | |
595 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
596 | details.</para></listitem> | |
798d3a52 ZJS |
597 | </varlistentry> |
598 | ||
599 | <varlistentry> | |
600 | <term><varname>SmackLabel=</varname></term> | |
601 | <term><varname>SmackLabelIPIn=</varname></term> | |
602 | <term><varname>SmackLabelIPOut=</varname></term> | |
603 | <listitem><para>Takes a string value. Controls the extended | |
604 | attributes <literal>security.SMACK64</literal>, | |
605 | <literal>security.SMACK64IPIN</literal> and | |
606 | <literal>security.SMACK64IPOUT</literal>, respectively, i.e. | |
607 | the security label of the FIFO, or the security label for the | |
608 | incoming or outgoing connections of the socket, respectively. | |
609 | See <ulink | |
610 | url="https://www.kernel.org/doc/Documentation/security/Smack.txt">Smack.txt</ulink> | |
611 | for details.</para></listitem> | |
612 | </varlistentry> | |
613 | ||
614 | <varlistentry> | |
615 | <term><varname>SELinuxContextFromNet=</varname></term> | |
616 | <listitem><para>Takes a boolean argument. When true, systemd | |
617 | will attempt to figure out the SELinux label used for the | |
618 | instantiated service from the information handed by the peer | |
619 | over the network. Note that only the security level is used | |
620 | from the information provided by the peer. Other parts of the | |
621 | resulting SELinux context originate from either the target | |
622 | binary that is effectively triggered by socket unit or from | |
623 | the value of the <varname>SELinuxContext=</varname> option. | |
624 | This configuration option only affects sockets with | |
625 | <varname>Accept=</varname> mode set to | |
626 | <literal>true</literal>. Also note that this option is useful | |
627 | only when MLS/MCS SELinux policy is deployed. Defaults to | |
628 | <literal>false</literal>. </para></listitem> | |
629 | </varlistentry> | |
630 | ||
631 | <varlistentry> | |
632 | <term><varname>PipeSize=</varname></term> | |
633 | <listitem><para>Takes a size in bytes. Controls the pipe | |
634 | buffer size of FIFOs configured in this socket unit. See | |
635 | <citerefentry><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
636 | for details. The usual suffixes K, M, G are supported and are | |
637 | understood to the base of 1024.</para></listitem> | |
638 | </varlistentry> | |
639 | ||
640 | <varlistentry> | |
641 | <term><varname>MessageQueueMaxMessages=</varname>, | |
642 | <varname>MessageQueueMessageSize=</varname></term> | |
643 | <listitem><para>These two settings take integer values and | |
644 | control the mq_maxmsg field or the mq_msgsize field, | |
645 | respectively, when creating the message queue. Note that | |
646 | either none or both of these variables need to be set. See | |
3ba3a79d | 647 | <citerefentry project='die-net'><refentrytitle>mq_setattr</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
798d3a52 ZJS |
648 | for details.</para></listitem> |
649 | </varlistentry> | |
650 | ||
651 | <varlistentry> | |
652 | <term><varname>FreeBind=</varname></term> | |
653 | <listitem><para>Takes a boolean value. Controls whether the | |
654 | socket can be bound to non-local IP addresses. This is useful | |
655 | to configure sockets listening on specific IP addresses before | |
656 | those IP addresses are successfully configured on a network | |
657 | interface. This sets the IP_FREEBIND socket option. For | |
658 | robustness reasons it is recommended to use this option | |
659 | whenever you bind a socket to a specific IP address. Defaults | |
660 | to <option>false</option>.</para></listitem> | |
661 | </varlistentry> | |
662 | ||
663 | <varlistentry> | |
664 | <term><varname>Transparent=</varname></term> | |
665 | <listitem><para>Takes a boolean value. Controls the | |
666 | IP_TRANSPARENT socket option. Defaults to | |
667 | <option>false</option>.</para></listitem> | |
668 | </varlistentry> | |
669 | ||
670 | <varlistentry> | |
671 | <term><varname>Broadcast=</varname></term> | |
e9dd6984 ZJS |
672 | <listitem><para>Takes a boolean value. This controls the <constant>SO_BROADCAST</constant> socket |
673 | option, which allows broadcast datagrams to be sent from this socket. Defaults to | |
798d3a52 ZJS |
674 | <option>false</option>.</para></listitem> |
675 | </varlistentry> | |
676 | ||
677 | <varlistentry> | |
678 | <term><varname>PassCredentials=</varname></term> | |
e9dd6984 ZJS |
679 | <listitem><para>Takes a boolean value. This controls the <constant>SO_PASSCRED</constant> socket |
680 | option, which allows <constant>AF_UNIX</constant> sockets to receive the credentials of the sending | |
681 | process in an ancillary message. Defaults to <option>false</option>.</para></listitem> | |
798d3a52 ZJS |
682 | </varlistentry> |
683 | ||
684 | <varlistentry> | |
685 | <term><varname>PassSecurity=</varname></term> | |
e9dd6984 ZJS |
686 | <listitem><para>Takes a boolean value. This controls the <constant>SO_PASSSEC</constant> socket |
687 | option, which allows <constant>AF_UNIX</constant> sockets to receive the security context of the | |
688 | sending process in an ancillary message. Defaults to <option>false</option>.</para></listitem> | |
798d3a52 ZJS |
689 | </varlistentry> |
690 | ||
a3d19f5d LP |
691 | <varlistentry> |
692 | <term><varname>PassPacketInfo=</varname></term> | |
693 | <listitem><para>Takes a boolean value. This controls the <constant>IP_PKTINFO</constant>, | |
694 | <constant>IPV6_RECVPKTINFO</constant> and <constant>NETLINK_PKTINFO</constant> socket options, which | |
695 | enable reception of additional per-packet metadata as ancillary message, on | |
696 | <constant>AF_INET</constant>, <constant>AF_INET6</constant> and <constant>AF_UNIX</constant> sockets. | |
697 | Defaults to <option>false</option>.</para></listitem> | |
698 | </varlistentry> | |
699 | ||
798d3a52 ZJS |
700 | <varlistentry> |
701 | <term><varname>TCPCongestion=</varname></term> | |
e9dd6984 ZJS |
702 | <listitem><para>Takes a string value. Controls the TCP congestion algorithm used by this |
703 | socket. Should be one of <literal>westwood</literal>, <literal>veno</literal>, | |
704 | <literal>cubic</literal>, <literal>lp</literal> or any other available algorithm supported by the IP | |
705 | stack. This setting applies only to stream sockets.</para></listitem> | |
798d3a52 ZJS |
706 | </varlistentry> |
707 | ||
708 | <varlistentry> | |
709 | <term><varname>ExecStartPre=</varname></term> | |
710 | <term><varname>ExecStartPost=</varname></term> | |
711 | <listitem><para>Takes one or more command lines, which are | |
712 | executed before or after the listening sockets/FIFOs are | |
713 | created and bound, respectively. The first token of the | |
714 | command line must be an absolute filename, then followed by | |
715 | arguments for the process. Multiple command lines may be | |
716 | specified following the same scheme as used for | |
717 | <varname>ExecStartPre=</varname> of service unit | |
718 | files.</para></listitem> | |
719 | </varlistentry> | |
720 | ||
721 | <varlistentry> | |
722 | <term><varname>ExecStopPre=</varname></term> | |
723 | <term><varname>ExecStopPost=</varname></term> | |
724 | <listitem><para>Additional commands that are executed before | |
725 | or after the listening sockets/FIFOs are closed and removed, | |
726 | respectively. Multiple command lines may be specified | |
727 | following the same scheme as used for | |
728 | <varname>ExecStartPre=</varname> of service unit | |
729 | files.</para></listitem> | |
730 | </varlistentry> | |
731 | ||
732 | <varlistentry> | |
733 | <term><varname>TimeoutSec=</varname></term> | |
734 | <listitem><para>Configures the time to wait for the commands | |
735 | specified in <varname>ExecStartPre=</varname>, | |
736 | <varname>ExecStartPost=</varname>, | |
737 | <varname>ExecStopPre=</varname> and | |
738 | <varname>ExecStopPost=</varname> to finish. If a command does | |
739 | not exit within the configured time, the socket will be | |
740 | considered failed and be shut down again. All commands still | |
741 | running will be terminated forcibly via | |
742 | <constant>SIGTERM</constant>, and after another delay of this | |
743 | time with <constant>SIGKILL</constant>. (See | |
744 | <option>KillMode=</option> in | |
745 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.) | |
746 | Takes a unit-less value in seconds, or a time span value such | |
747 | as "5min 20s". Pass <literal>0</literal> to disable the | |
748 | timeout logic. Defaults to | |
749 | <varname>DefaultTimeoutStartSec=</varname> from the manager | |
750 | configuration file (see | |
751 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
752 | </para></listitem> | |
753 | </varlistentry> | |
754 | ||
755 | <varlistentry> | |
756 | <term><varname>Service=</varname></term> | |
757 | <listitem><para>Specifies the service unit name to activate on | |
758 | incoming traffic. This setting is only allowed for sockets | |
759 | with <varname>Accept=no</varname>. It defaults to the service | |
760 | that bears the same name as the socket (with the suffix | |
761 | replaced). In most cases, it should not be necessary to use | |
c129bd5d LP |
762 | this option. Note that setting this parameter might result in |
763 | additional dependencies to be added to the unit (see | |
764 | above).</para></listitem> | |
798d3a52 ZJS |
765 | </varlistentry> |
766 | ||
767 | <varlistentry> | |
768 | <term><varname>RemoveOnStop=</varname></term> | |
e9dd6984 ZJS |
769 | <listitem><para>Takes a boolean argument. If enabled, any file nodes created by this socket unit are |
770 | removed when it is stopped. This applies to <constant>AF_UNIX</constant> sockets in the file system, | |
771 | POSIX message queues, FIFOs, as well as any symlinks to them configured with | |
772 | <varname>Symlinks=</varname>. Normally, it should not be necessary to use this option, and is not | |
773 | recommended as services might continue to run after the socket unit has been terminated and it should | |
774 | still be possible to communicate with them via their file system node. Defaults to | |
798d3a52 ZJS |
775 | off.</para></listitem> |
776 | </varlistentry> | |
777 | ||
778 | <varlistentry> | |
779 | <term><varname>Symlinks=</varname></term> | |
3ecc7fc3 LP |
780 | <listitem><para>Takes a list of file system paths. The specified paths will be created as symlinks to the |
781 | <constant>AF_UNIX</constant> socket path or FIFO path of this socket unit. If this setting is used, only one | |
782 | <constant>AF_UNIX</constant> socket in the file system or one FIFO may be configured for the socket unit. Use | |
783 | this option to manage one or more symlinked alias names for a socket, binding their lifecycle together. Note | |
784 | that if creation of a symlink fails this is not considered fatal for the socket unit, and the socket unit may | |
785 | still start. If an empty string is assigned, the list of paths is reset. Defaults to an empty | |
786 | list.</para></listitem> | |
798d3a52 ZJS |
787 | </varlistentry> |
788 | ||
8dd4c05b LP |
789 | <varlistentry> |
790 | <term><varname>FileDescriptorName=</varname></term> | |
791 | <listitem><para>Assigns a name to all file descriptors this | |
792 | socket unit encapsulates. This is useful to help activated | |
a8eaaee7 | 793 | services identify specific file descriptors, if multiple fds |
8dd4c05b LP |
794 | are passed. Services may use the |
795 | <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
796 | call to acquire the names configured for the received file | |
797 | descriptors. Names may contain any ASCII character, but must | |
a8eaaee7 | 798 | exclude control characters and <literal>:</literal>, and must |
8dd4c05b | 799 | be at most 255 characters in length. If this setting is not |
b938cb90 | 800 | used, the file descriptor name defaults to the name of the |
8dd4c05b LP |
801 | socket unit, including its <filename>.socket</filename> |
802 | suffix.</para></listitem> | |
803 | </varlistentry> | |
804 | ||
8b26cdbd LP |
805 | <varlistentry> |
806 | <term><varname>TriggerLimitIntervalSec=</varname></term> | |
db985064 | 807 | <term><varname>TriggerLimitBurst=</varname></term> |
8b26cdbd LP |
808 | |
809 | <listitem><para>Configures a limit on how often this socket unit my be activated within a specific time | |
810 | interval. The <varname>TriggerLimitIntervalSec=</varname> may be used to configure the length of the time | |
811 | interval in the usual time units <literal>us</literal>, <literal>ms</literal>, <literal>s</literal>, | |
1f15ce28 | 812 | <literal>min</literal>, <literal>h</literal>, … and defaults to 2s (See |
8b26cdbd | 813 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details on |
1f15ce28 LP |
814 | the various time units understood). The <varname>TriggerLimitBurst=</varname> setting takes a positive integer |
815 | value and specifies the number of permitted activations per time interval, and defaults to 200 for | |
816 | <varname>Accept=yes</varname> sockets (thus by default permitting 200 activations per 2s), and 20 otherwise (20 | |
817 | activations per 2s). Set either to 0 to disable any form of trigger rate limiting. If the limit is hit, the | |
818 | socket unit is placed into a failure mode, and will not be connectible anymore until restarted. Note that this | |
819 | limit is enforced before the service activation is enqueued.</para></listitem> | |
8b26cdbd LP |
820 | </varlistentry> |
821 | ||
798d3a52 ZJS |
822 | </variablelist> |
823 | ||
824 | <para>Check | |
825 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
826 | and | |
827 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
828 | for more settings.</para> | |
829 | ||
830 | </refsect1> | |
831 | ||
832 | <refsect1> | |
833 | <title>See Also</title> | |
834 | <para> | |
835 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
836 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
d1698b82 | 837 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
798d3a52 ZJS |
838 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
839 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
840 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
841 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
842 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
8dd4c05b LP |
843 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
844 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
845 | <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
798d3a52 | 846 | </para> |
798d3a52 ZJS |
847 | <para> |
848 | For more extensive descriptions see the "systemd for Developers" series: | |
849 | <ulink url="http://0pointer.de/blog/projects/socket-activation.html">Socket Activation</ulink>, | |
850 | <ulink url="http://0pointer.de/blog/projects/socket-activation2.html">Socket Activation, part II</ulink>, | |
851 | <ulink url="http://0pointer.de/blog/projects/inetd.html">Converting inetd Services</ulink>, | |
852 | <ulink url="http://0pointer.de/blog/projects/socket-activated-containers.html">Socket Activated Internet Services and OS Containers</ulink>. | |
853 | </para> | |
854 | </refsect1> | |
1f812fea LP |
855 | |
856 | </refentry> |