man/systemd.socket.xml

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  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>Socket unit configuration</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
  58                 <filename>.socket</filename> encodes information about
  59                 an IPC or network socket or a file system FIFO
  60                 controlled and supervised by systemd, for socket-based
  61                 activation.</para>
  62
  63                 <para>This man page lists the configuration options
  64                 specific to this unit type. See
  65                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  66                 for the common options of all unit configuration
  67                 files. The common configuration items are configured
  68                 in the generic [Unit] and [Install] sections. The
  69                 socket specific configuration options are configured
  70                 in the [Socket] section.</para>
  71
  72                 <para>Additional options are listed in
  73                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  74                 which define the execution environment the
  75                 <option>ExecStartPre=</option>,
  76                 <option>ExecStartPost=</option>,
  77                 <option>ExecStopPre=</option> and
  78                 <option>ExecStoptPost=</option> commands are executed
  79                 in, and in
  80                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  81                 which define the way the processes are
  82                 terminated.</para>
  83
  84                 <para>For each socket file a matching service file
  85                 (see
  86                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  87                 for details) must exist, describing the service to
  88                 start on incoming traffic on the socket. Depending on
  89                 the setting of <option>Accept=</option> (see below),
  90                 this must either be named like the socket unit, but
  91                 with the suffix replaced; or it must be a template
  92                 file named the same way. Example: a socket file
  93                 <filename>foo.socket</filename> needs a matching
  94                 service <filename>foo.service</filename> if
  95                 <option>Accept=false</option> is set. If
  96                 <option>Accept=true</option> is set a service template
  97                 file <filename>foo@.service</filename> must exist from
  98                 which services are instantiated for each incoming
  99                 connection.</para>
 100
 101                 <para>Unless <varname>DefaultDependencies=</varname>
 102                 is set to <option>false</option>, socket units will
 103                 implicitly have dependencies of type
 104                 <varname>Requires=</varname> and
 105                 <varname>After=</varname> on
 106                 <filename>sysinit.target</filename> as well as
 107                 dependencies of type <varname>Conflicts=</varname> and
 108                 <varname>Before=</varname> on
 109                 <filename>shutdown.target</filename>. These ensure
 110                 that socket units pull in basic system
 111                 initialization, and are terminated cleanly prior to
 112                 system shutdown. Only sockets involved with early
 113                 boot or late system shutdown should disable this
 114                 option.</para>
 115
 116                 <para>Socket units may be used to implement on-demand
 117                 starting of services, as well as parallelized starting
 118                 of services.</para>
 119
 120                 <para>Note that the daemon software configured for
 121                 socket activation with socket units needs to be able
 122                 to accept sockets from systemd, either via systemd's
 123                 native socket passing interface (see
 124                 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 125                 for details) or via the traditional
 126                 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>-style
 127                 socket passing (i.e. sockets passed in via STDIN and
 128                 STDOUT, using <varname>StandardInput=socket</varname>
 129                 in the service file).</para>
 130         </refsect1>
 131
 132         <refsect1>
 133                 <title>Options</title>
 134
 135                 <para>Socket files must include a [Socket] section,
 136                 which carries information about the socket or FIFO it
 137                 supervises. A number of options that may be used in
 138                 this section are shared with other unit types. These
 139                 options are documented in
 140                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 141                 and
 142                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
 143                 options specific to the [Socket] section of socket
 144                 units are the following:</para>
 145
 146                 <variablelist>
 147                         <varlistentry>
 148                                 <term><varname>ListenStream=</varname></term>
 149                                 <term><varname>ListenDatagram=</varname></term>
 150                                 <term><varname>ListenSequentialPacket=</varname></term>
 151                                 <listitem><para>Specifies an address
 152                                 to listen on for a stream
 153                                 (SOCK_STREAM), datagram (SOCK_DGRAM)
 154                                 resp. sequential packet
 155                                 (SOCK_SEQPACKET) socket. The address
 156                                 can be written in various formats:</para>
 157
 158                                 <para>If the address starts with a
 159                                 slash (/), it is read as file system
 160                                 socket in the AF_UNIX socket
 161                                 family.</para>
 162
 163                                 <para>If the address starts with an
 164                                 at symbol (@) it is read as abstract
 165                                 namespace socket in the AF_UNIX
 166                                 family. The @ is replaced with a NUL
 167                                 character before binding. For details
 168                                 see
 169                                 <citerefentry><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 170
 171                                 <para>If the address string is a
 172                                 single number it is read as port
 173                                 number to listen on for both IPv4 and
 174                                 IPv6.</para>
 175
 176                                 <para>If the address string is a
 177                                 string in the format v.w.x.y:z it is
 178                                 read as IPv4 specifier for listening
 179                                 on an address v.w.x.y on a port
 180                                 z.</para>
 181
 182                                 <para>If the address string is a
 183                                 string in the format [x]:y it is read
 184                                 as IPv6 address x on a port y.</para>
 185
 186                                 <para>Note that SOCK_SEQPACKET
 187                                 (i.e. <varname>ListenSequentialPacket=</varname>)
 188                                 is only available for AF_UNIX
 189                                 sockets. SOCK_STREAM
 190                                 (i.e. <varname>ListenStream=</varname>)
 191                                 when used for IP sockets refers to TCP
 192                                 sockets, SOCK_DGRAM
 193                                 (i.e. <varname>ListenDatagram=</varname>)
 194                                 to UDP.</para>
 195
 196                                 <para>These options may be specified
 197                                 more than once in which case incoming
 198                                 traffic on any of the sockets will trigger
 199                                 service activation, and all listed
 200                                 sockets will be passed to the service,
 201                                 regardless whether there is incoming
 202                                 traffic on them or not.</para>
 203
 204                                 <para>If an IP address is used here, it
 205                                 is often desirable to listen on it
 206                                 before the interface it is configured
 207                                 on is up and running, and even
 208                                 regardless whether it will be up and
 209                                 running ever at all. To deal with this it is
 210                                 recommended to set the
 211                                 <varname>FreeBind=</varname> option
 212                                 described below.</para></listitem>
 213                         </varlistentry>
 214
 215                         <varlistentry>
 216                                 <term><varname>ListenFIFO=</varname></term>
 217                                 <listitem><para>Specifies a file
 218                                 system FIFO to listen on. This expects
 219                                 an absolute file system path as
 220                                 argument. Behavior otherwise is very
 221                                 similar to the
 222                                 <varname>ListenDatagram=</varname>
 223                                 directive above.</para></listitem>
 224                         </varlistentry>
 225
 226                         <varlistentry>
 227                                 <term><varname>ListenSpecial=</varname></term>
 228                                 <listitem><para>Specifies a special
 229                                 file in the file system to listen
 230                                 on. This expects an absolute file
 231                                 system path as argument. Behavior
 232                                 otherwise is very similar to the
 233                                 <varname>ListenFIFO=</varname>
 234                                 directive above. Use this to open
 235                                 character device nodes as well as
 236                                 special files in
 237                                 <filename>/proc</filename> and
 238                                 <filename>/sys</filename>.</para></listitem>
 239                         </varlistentry>
 240
 241                         <varlistentry>
 242                                 <term><varname>ListenNetlink=</varname></term>
 243                                 <listitem><para>Specifies a Netlink
 244                                 family to create a socket for to
 245                                 listen on. This expects a short string
 246                                 referring to the AF_NETLINK family
 247                                 name (such as <varname>audit</varname>
 248                                 or <varname>kobject-uevent</varname>)
 249                                 as argument, optionally suffixed by a
 250                                 whitespace followed by a multicast
 251                                 group integer. Behavior otherwise is
 252                                 very similar to the
 253                                 <varname>ListenDatagram=</varname>
 254                                 directive above.</para></listitem>
 255                         </varlistentry>
 256
 257                         <varlistentry>
 258                                 <term><varname>ListenMessageQueue=</varname></term>
 259                                 <listitem><para>Specifies a POSIX
 260                                 message queue name to listen on. This
 261                                 expects a valid message queue name
 262                                 (i.e. beginning with /). Behavior
 263                                 otherwise is very similar to the
 264                                 <varname>ListenFIFO=</varname>
 265                                 directive above. On Linux message
 266                                 queue descriptors are actually file
 267                                 descriptors and can be inherited
 268                                 between processes.</para></listitem>
 269                         </varlistentry>
 270
 271                         <varlistentry>
 272                                 <term><varname>BindIPv6Only=</varname></term>
 273                                 <listitem><para>Takes a one of
 274                                 <option>default</option>,
 275                                 <option>both</option> or
 276                                 <option>ipv6-only</option>. Controls
 277                                 the IPV6_V6ONLY socket option (see
 278                                 <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 279                                 for details). If
 280                                 <option>both</option>, IPv6 sockets
 281                                 bound will be accessible via both IPv4
 282                                 and IPv6. If
 283                                 <option>ipv6-only</option>, they will
 284                                 be accessible via IPv6 only. If
 285                                 <option>default</option> (which is the
 286                                 default, surprise!) the system wide
 287                                 default setting is used, as controlled
 288                                 by
 289                                 <filename>/proc/sys/net/ipv6/bindv6only</filename>.</para>
 290                                 </listitem>
 291                         </varlistentry>
 292
 293                         <varlistentry>
 294                                 <term><varname>Backlog=</varname></term>
 295                                 <listitem><para>Takes an unsigned
 296                                 integer argument. Specifies the number
 297                                 of connections to queue that have not
 298                                 been accepted yet. This setting
 299                                 matters only for stream and sequential
 300                                 packet sockets. See
 301                                 <citerefentry><refentrytitle>listen</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 302                                 for details. Defaults to SOMAXCONN
 303                                 (128).</para></listitem>
 304                         </varlistentry>
 305
 306                         <varlistentry>
 307                                 <term><varname>BindToDevice=</varname></term>
 308                                 <listitem><para>Specifies a network
 309                                 interface name to bind this socket
 310                                 to. If set traffic will only be
 311                                 accepted from the specified network
 312                                 interfaces. This controls the
 313                                 SO_BINDTODEVICE socket option (see
 314                                 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 315                                 for details). If this option is used,
 316                                 an automatic dependency from this
 317                                 socket unit on the network interface
 318                                 device unit
 319                                 (<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 320                                 is created.</para></listitem>
 321                         </varlistentry>
 322
 323                         <varlistentry>
 324                                 <term><varname>DirectoryMode=</varname></term>
 325                                 <listitem><para>If listening on a file
 326                                 system socket of FIFO, the parent
 327                                 directories are automatically created
 328                                 if needed. This option specifies the
 329                                 file system access mode used when
 330                                 creating these directories. Takes an
 331                                 access mode in octal
 332                                 notation. Defaults to
 333                                 0755.</para></listitem>
 334                         </varlistentry>
 335
 336                         <varlistentry>
 337                                 <term><varname>SocketMode=</varname></term>
 338                                 <listitem><para>If listening on a file
 339                                 system socket of FIFO, this option
 340                                 specifies the file system access mode
 341                                 used when creating the file
 342                                 node. Takes an access mode in octal
 343                                 notation. Defaults to
 344                                 0666.</para></listitem>
 345                         </varlistentry>
 346
 347                         <varlistentry>
 348                                 <term><varname>Accept=</varname></term>
 349                                 <listitem><para>Takes a boolean
 350                                 argument. If true, a service instance
 351                                 is spawned for each incoming
 352                                 connection and only the connection
 353                                 socket is passed to it. If false, all
 354                                 listening sockets themselves are
 355                                 passed to the started service unit,
 356                                 and only one service unit is spawned
 357                                 for all connections (also see
 358                                 above). This value is ignored for
 359                                 datagram sockets and FIFOs where
 360                                 a single service unit unconditionally
 361                                 handles all incoming traffic. Defaults
 362                                 to <option>false</option>. For
 363                                 performance reasons, it is recommended
 364                                 to write new daemons only in a way
 365                                 that is suitable for
 366                                 <option>Accept=false</option>. This
 367                                 option is mostly useful to allow
 368                                 daemons designed for usage with
 369                                 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 370                                 to work unmodified with systemd socket
 371                                 activation.</para></listitem>
 372                         </varlistentry>
 373
 374                         <varlistentry>
 375                                 <term><varname>MaxConnections=</varname></term>
 376                                 <listitem><para>The maximum number of
 377                                 connections to simultaneously run
 378                                 services instances for, when
 379                                 <option>Accept=true</option> is
 380                                 set. If more concurrent connections
 381                                 are coming in, they will be refused
 382                                 until at least one existing connection
 383                                 is terminated. This setting has no
 384                                 effect for sockets configured with
 385                                 <option>Accept=no</option> or datagram
 386                                 sockets. Defaults to
 387                                 64.</para></listitem>
 388                         </varlistentry>
 389
 390                         <varlistentry>
 391                                 <term><varname>KeepAlive=</varname></term>
 392                                 <listitem><para>Takes a boolean
 393                                 argument. If true, the TCP/IP stack
 394                                 will send a keep alive message after
 395                                 2h (depending on the configuration of
 396                                 <filename>/proc/sys/net/ipv4/tcp_keepalive_time</filename>)
 397                                 for all TCP streams accepted on this
 398                                 socket. This controls the SO_KEEPALIVE
 399                                 socket option (see
 400                                 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 401                                 and the <ulink
 402                                 url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
 403                                 Keepalive HOWTO</ulink> for details.)
 404                                 Defaults to
 405                                 <option>false</option>.</para></listitem>
 406                         </varlistentry>
 407
 408                         <varlistentry>
 409                                 <term><varname>Priority=</varname></term>
 410                                 <listitem><para>Takes an integer
 411                                 argument controlling the priority for
 412                                 all traffic sent from this
 413                                 socket. This controls the SO_PRIORITY
 414                                 socket option (see
 415                                 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 416                                 for details.).</para></listitem>
 417                         </varlistentry>
 418
 419                         <varlistentry>
 420                                 <term><varname>ReceiveBuffer=</varname></term>
 421                                 <term><varname>SendBuffer=</varname></term>
 422                                 <listitem><para>Takes an integer
 423                                 argument controlling the receive
 424                                 resp. send buffer sizes of this
 425                                 socket. This controls the SO_RCVBUF
 426                                 resp. SO_SNDBUF socket options (see
 427                                 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 428                                 for details.).</para></listitem>
 429                         </varlistentry>
 430
 431                         <varlistentry>
 432                                 <term><varname>IPTOS=</varname></term>
 433                                 <listitem><para>Takes an integer
 434                                 argument controlling the IP
 435                                 Type-Of-Service field for packets
 436                                 generated from this socket. This
 437                                 controls the IP_TOS socket option (see
 438                                 <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 439                                 for details.). Either a numeric string
 440                                 or one of <option>low-delay</option>,
 441                                 <option>throughput</option>,
 442                                 <option>reliability</option> or
 443                                 <option>low-cost</option> may be
 444                                 specified.</para></listitem>
 445                         </varlistentry>
 446
 447                         <varlistentry>
 448                                 <term><varname>IPTTL=</varname></term>
 449                                 <listitem><para>Takes an integer
 450                                 argument controlling the IPv4
 451                                 Time-To-Live/IPv6 Hop-Count field for
 452                                 packets generated from this
 453                                 socket. This sets the
 454                                 IP_TTL/IPV6_UNICAST_HOPS socket
 455                                 options (see
 456                                 <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 457                                 and
 458                                 <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 459                                 for details.)</para></listitem>
 460                         </varlistentry>
 461
 462                         <varlistentry>
 463                                 <term><varname>Mark=</varname></term>
 464                                 <listitem><para>Takes an integer
 465                                 value. Controls the firewall mark of
 466                                 packets generated by this socket. This
 467                                 can be used in the firewall logic to
 468                                 filter packets from this socket. This
 469                                 sets the SO_MARK socket option. See
 470                                 <citerefentry><refentrytitle>iptables</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 471                                 for details.</para></listitem>
 472                         </varlistentry>
 473
 474                         <varlistentry>
 475                                 <term><varname>PipeSize=</varname></term>
 476                                 <listitem><para>Takes an integer
 477                                 value. Controls the pipe buffer size
 478                                 of FIFOs configured in this socket
 479                                 unit.  See
 480                                 <citerefentry><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 481                                 for details.</para></listitem>
 482                         </varlistentry>
 483
 484                         <varlistentry>
 485                                 <term><varname>MessageQueueMaxMessages=</varname>,
 486                                 <varname>MessageQueueMessageSize=</varname></term>
 487                                 <listitem><para>These two settings
 488                                 take integer values and control the
 489                                 mq_maxmsg resp. mq_msgsize field when
 490                                 creating the message queue. Note that
 491                                 either none or both of these variables
 492                                 need to be set. See
 493                                 <citerefentry><refentrytitle>mq_setattr</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 494                                 for details.</para></listitem>
 495                         </varlistentry>
 496
 497                         <varlistentry>
 498                                 <term><varname>FreeBind=</varname></term>
 499                                 <listitem><para>Takes a boolean
 500                                 value. Controls whether the socket can
 501                                 be bound to non-local IP
 502                                 addresses. This is useful to configure
 503                                 sockets listening on specific IP
 504                                 addresses before those IP addresses
 505                                 are successfully configured on a
 506                                 network interface. This sets the
 507                                 IP_FREEBIND socket option. For
 508                                 robustness reasons it is recommended
 509                                 to use this option whenever you bind a
 510                                 socket to a specific IP
 511                                 address. Defaults to <option>false</option>.</para></listitem>
 512                         </varlistentry>
 513
 514                         <varlistentry>
 515                                 <term><varname>Transparent=</varname></term>
 516                                 <listitem><para>Takes a boolean
 517                                 value. Controls the IP_TRANSPARENT
 518                                 socket option. Defaults to
 519                                 <option>false</option>.</para></listitem>
 520                         </varlistentry>
 521
 522                         <varlistentry>
 523                                 <term><varname>Broadcast=</varname></term>
 524                                 <listitem><para>Takes a boolean
 525                                 value. This controls the SO_BROADCAST
 526                                 socket option, which allows broadcast
 527                                 datagrams to be sent from this
 528                                 socket. Defaults to
 529                                 <option>false</option>.</para></listitem>
 530                         </varlistentry>
 531
 532                         <varlistentry>
 533                                 <term><varname>PassCredentials=</varname></term>
 534                                 <listitem><para>Takes a boolean
 535                                 value. This controls the SO_PASSCRED
 536                                 socket option, which allows AF_UNIX sockets to
 537                                 receive the credentials of the sending
 538                                 process in an ancillary message.
 539                                 Defaults to
 540                                 <option>false</option>.</para></listitem>
 541                         </varlistentry>
 542
 543                         <varlistentry>
 544                                 <term><varname>PassSecurity=</varname></term>
 545                                 <listitem><para>Takes a boolean
 546                                 value. This controls the SO_PASSSEC
 547                                 socket option, which allows AF_UNIX
 548                                 sockets to receive the security
 549                                 context of the sending process in an
 550                                 ancillary message.  Defaults to
 551                                 <option>false</option>.</para></listitem>
 552                         </varlistentry>
 553
 554                         <varlistentry>
 555                                 <term><varname>TCPCongestion=</varname></term>
 556                                 <listitem><para>Takes a string
 557                                 value. Controls the TCP congestion
 558                                 algorithm used by this socket. Should
 559                                 be one of "westwood", "veno", "cubic",
 560                                 "lp" or any other available algorithm
 561                                 supported by the IP stack. This
 562                                 setting applies only to stream
 563                                 sockets.</para></listitem>
 564                         </varlistentry>
 565
 566                         <varlistentry>
 567                                 <term><varname>ExecStartPre=</varname></term>
 568                                 <term><varname>ExecStartPost=</varname></term>
 569                                 <listitem><para>Takes one or more
 570                                 command lines, which are executed
 571                                 before (resp. after) the listening
 572                                 sockets/FIFOs are created and
 573                                 bound. The first token of the command
 574                                 line must be an absolute file name,
 575                                 then followed by arguments for the
 576                                 process. Multiple command lines may be
 577                                 specified following the same scheme as
 578                                 used for
 579                                 <varname>ExecStartPre=</varname> of
 580                                 service unit files.</para></listitem>
 581                         </varlistentry>
 582
 583                         <varlistentry>
 584                                 <term><varname>ExecStopPre=</varname></term>
 585                                 <term><varname>ExecStopPost=</varname></term>
 586                                 <listitem><para>Additional commands
 587                                 that are executed before (resp. after)
 588                                 the listening sockets/FIFOs are closed
 589                                 and removed. Multiple command lines
 590                                 may be specified following the same
 591                                 scheme as used for
 592                                 <varname>ExecStartPre=</varname> of
 593                                 service unit files.</para></listitem>
 594                         </varlistentry>
 595
 596                         <varlistentry>
 597                                 <term><varname>TimeoutSec=</varname></term>
 598                                 <listitem><para>Configures the time to
 599                                 wait for the commands specified in
 600                                 <varname>ExecStartPre=</varname>,
 601                                 <varname>ExecStartPost=</varname>,
 602                                 <varname>ExecStopPre=</varname> and
 603                                 <varname>ExecStopPost=</varname> to
 604                                 finish. If a command does not exit
 605                                 within the configured time, the socket
 606                                 will be considered failed and be shut
 607                                 down again. All commands still running,
 608                                 will be terminated forcibly via
 609                                 SIGTERM, and after another delay of
 610                                 this time with SIGKILL. (See
 611                                 <option>KillMode=</option> in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
 612                                 Takes a unit-less value in seconds, or
 613                                 a time span value such as "5min
 614                                 20s". Pass 0 to disable the timeout
 615                                 logic. Defaults to
 616                                 90s.</para></listitem>
 617                         </varlistentry>
 618
 619                         <varlistentry>
 620                                 <term><varname>Service=</varname></term>
 621                                 <listitem><para>Specifies the service
 622                                 unit name to activate on incoming
 623                                 traffic. This defaults to the service
 624                                 that bears the same name as the socket
 625                                 (ignoring the different suffixes). In
 626                                 most cases it should not be necessary
 627                                 to use this option.</para></listitem>
 628                         </varlistentry>
 629
 630                 </variablelist>
 631
 632                 <para>Check
 633                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 634                 and
 635                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 636                 for more settings.</para>
 637
 638         </refsect1>
 639
 640         <refsect1>
 641                   <title>See Also</title>
 642                   <para>
 643                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 644                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 645                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 646                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 647                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 648                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 649                   </para>
 650         </refsect1>
 651
 652 </refentry>