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<refentry id="systemd.socket">
- <refentryinfo>
- <title>systemd.socket</title>
- <productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
- </refentryinfo>
-
- <refmeta>
- <refentrytitle>systemd.socket</refentrytitle>
- <manvolnum>5</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>systemd.socket</refname>
- <refpurpose>systemd socket configuration files</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <para><filename>systemd.socket</filename></para>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para>A unit configuration file whose name ends in
- <filename>.socket</filename> encodes information about
- an IPC or network socket or a file system FIFO
- controlled and supervised by systemd, for socket-based
- activation.</para>
-
- <para>This man page lists the configuration options
- specific to this unit type. See
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for the common options of all unit configuration
- files. The common configuration items are configured
- in the generic [Unit] and [Install] sections. The
- socket specific configuration options are configured
- in the [Socket] section.</para>
-
- <para>Additional options are listed in
- <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- which define the execution environment the
- <option>ExecStartPre=</option>,
- <option>ExecStartPost=</option>,
- <option>ExecStopPre=</option> and
- <option>ExecStoptPost=</option> commands are executed
- in.</para>
-
- <para>For each socket file a matching service file
- (see
- <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details) must exist, describing the service to
- start on incoming traffic on the socket. Depending on
- the setting of <option>Accept=</option> (see below),
- this must either be named like the socket unit, but
- with the suffix replaced; or it must be a template
- file named the same way. Example: a socket file
- <filename>foo.socket</filename> needs a matching
- service <filename>foo.service</filename> if
- <option>Accept=false</option> is set. If
- <option>Accept=true</option> is set a service template
- file <filename>foo@.service</filename> must exist from
- which services are instantiated for each incoming
- connection.</para>
-
- <para>Unless <varname>DefaultDependencies=</varname>
- is set to <option>false</option>, socket units will
- implicitly have dependencies of type
- <varname>Requires=</varname> and
- <varname>After=</varname> on
- <filename>sysinit.target</filename> as well as
- dependencies of type <varname>Conflicts=</varname> and
- <varname>Before=</varname> on
- <filename>shutdown.target</filename>. These ensure
- that socket units pull in basic system
- initialization, and are terminated cleanly prior to
- system shutdown. Only sockets involved with early
- boot or late system shutdown should disable this
- option.</para>
-
- <para>Socket units may be used to implement on-demand
- starting of services, as well as parallelized starting
- of services.</para>
- </refsect1>
-
- <refsect1>
- <title>Options</title>
-
- <para>Socket files must include a [Socket] section,
- which carries information about the socket or FIFO it
- supervises. A number of options that may be used in
- this section are shared with other unit types. These
- options are documented in
- <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
- options specific to the [Socket] section of socket
- units are the following:</para>
-
- <variablelist>
- <varlistentry>
- <term><varname>ListenStream=</varname></term>
- <term><varname>ListenDatagram=</varname></term>
- <term><varname>ListenSequentialPacket=</varname></term>
- <listitem><para>Specifies an address
- to listen on for a stream
- (SOCK_STREAM), datagram (SOCK_DGRAM)
- resp. sequential packet
- (SOCK_SEQPACKET) socket. The address
- can be written in various formats:</para>
-
- <para>If the address starts with a
- slash (/), it is read as file system
- socket in the AF_UNIX socket
- family.</para>
-
- <para>If the address starts with an
- ampersand (@) it is read as abstract
- namespace socket in the AF_UNIX
- family. The @ is replaced with a NUL
- character before binding. For details
- see
- <citerefentry><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
-
- <para>If the address string is a
- single number it is read as port
- number to listen on for both IPv4 and
- IPv6.</para>
-
- <para>If the address string is a
- string in the format v.w.x.y:z it is
- read as IPv4 specifier for listening
- on an address v.w.x.y on a port
- z.</para>
-
- <para>If the address string is a
- string in the format [x]:y it is read
- as IPv6 address x on a port y.</para>
-
- <para>Note that SOCK_SEQPACKET
- (i.e. <varname>ListenSequentialPacket=</varname>)
- is only available for AF_UNIX
- sockets. SOCK_STREAM
- (i.e. <varname>ListenStream=</varname>)
- when used for IP sockets refers to TCP
- sockets, SOCK_DGRAM
- (i.e. <varname>ListenDatagram=</varname>)
- to UDP.</para>
-
- <para>These options may be specified
- more than once in which case incoming
- traffic on any of the sockets will trigger
- service activation, and all listed
- sockets will be passed to the service,
- regardless whether there is incoming
- traffic on them or not.</para>
-
- <para>If an IP address is used here, it
- is often desirable to listen on it
- before the interface it is configured
- on is up and running, and even
- regardless whether it will be up and
- running ever at all. To deal with this it is
- recommended to set the
- <varname>FreeBind=</varname> option
- described below.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ListenFIFO=</varname></term>
- <listitem><para>Specifies a file
- system FIFO to listen on. This expects
- an absolute file system path as
- argument. Behaviour otherwise is very
- similar to the
- <varname>ListenDatagram=</varname>
- directive above.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BindIPv6Only=</varname></term>
- <listitem><para>Takes a one of
- <option>default</option>,
- <option>both</option> or
- <option>ipv6-only</option>. Controls
- the IPV6_V6ONLY socket option (see
- <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details). If
- <option>both</option>, IPv6 sockets
- bound will be accessible via both IPv4
- and IPv6. If
- <option>ipv6-only</option>, they will
- be accessible via IPv6 only. If
- <option>default</option> (which is the
- default, surprise!) the system wide
- default setting is used, as controlled
- by
- <filename>/proc/sys/net/ipv6/bindv6only</filename>.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Backlog=</varname></term>
- <listitem><para>Takes an unsigned
- integer argument. Specifies the number
- of connections to queue that have not
- been accepted yet. This setting
- matters only for stream and sequential
- packet sockets. See
- <citerefentry><refentrytitle>listen</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details. Defaults to SOMAXCONN
- (128).</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BindToDevice=</varname></term>
- <listitem><para>Specifies a network
- interface name to bind this socket
- to. If set traffic will only be
- accepted from the specified network
- interfaces. This controls the
- SO_BINDTODEVICE socket option (see
- <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details). If this option is used,
- an automatic dependency from this
- socket unit on the network interface
- device unit
- (<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- is created.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>DirectoryMode=</varname></term>
- <listitem><para>If listening on a file
- system socket of FIFO, the parent
- directories are automatically created
- if needed. This option specifies the
- file system access mode used when
- creating these directories. Takes an
- access mode in octal
- notation. Defaults to
- 0755.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SocketMode=</varname></term>
- <listitem><para>If listening on a file
- system socket of FIFO, this option
- specifies the file system access mode
- used when creating the file
- node. Takes an access mode in octal
- notation. Defaults to
- 0666.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Accept=</varname></term>
- <listitem><para>Takes a boolean
- argument. If true, a service instance
- is spawned for each incoming
- connection and only the connection
- socket is passed to it. If false, all
- listening sockets themselves are
- passed to the started service unit,
- and only one service unit is spawned
- for all connections (also see
- above). This value is ignored for
- datagram sockets and FIFOs where
- a single service unit unconditionally
- handles all incoming traffic. Defaults
- to <option>false</option>. For
- performance reasons, it is recommended
- to write new daemons only in a way
- that is suitable for
- <option>Accept=false</option>. This
- option is mostly useful to allow
- daemons designed for usage with
- <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- to work unmodified with systemd socket
- activation.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>MaxConnections=</varname></term>
- <listitem><para>The maximum number of
- connections to simultaneously run
- services instances for, when
- <option>Accept=true</option> is
- set. If more concurrent connections
- are coming in, they will be refused
- until at least one existing connection
- is terminated. This setting has no
- effect for sockets configured with
- <option>Accept=no</option> or datagram
- sockets. Defaults to
- 64.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>KeepAlive=</varname></term>
- <listitem><para>Takes a boolean
- argument. If true, the TCP/IP stack
- will send a keep alive message after
- 2h (depending on the configuration of
- <filename>/proc/sys/net/ipv4/tcp_keepalive_time</filename>)
- for all TCP streams accepted on this
- socket. This controls the SO_KEEPALIVE
- socket option (see
- <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- and the <ulink
- url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
- Keepalive HOWTO</ulink> for details.)
- Defaults to
- <option>false</option>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Priority=</varname></term>
- <listitem><para>Takes an integer
- argument controlling the priority for
- all traffic sent from this
- socket. This controls the SO_PRIORITY
- socket option (see
- <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details.).</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ReceiveBuffer=</varname></term>
- <term><varname>SendBuffer=</varname></term>
- <listitem><para>Takes an integer
- argument controlling the receive
- resp. send buffer sizes of this
- socket. This controls the SO_RCVBUF
- resp. SO_SNDBUF socket options (see
- <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details.).</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>IPTOS=</varname></term>
- <listitem><para>Takes an integer
- argument controlling the IP
- Type-Of-Service field for packets
- generated from this socket. This
- controls the IP_TOS socket option (see
- <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details.). Either a numeric string
- or one of <option>low-delay</option>,
- <option>throughput</option>,
- <option>reliability</option> or
- <option>low-cost</option> may be
- specified.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>IPTTL=</varname></term>
- <listitem><para>Takes an integer
- argument controlling the IPv4
- Time-To-Live/IPv6 Hop-Count field for
- packets generated from this
- socket. This sets the
- IP_TTL/IPV6_UNICAST_HOPS socket
- options (see
- <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- and
- <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details.)</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Mark=</varname></term>
- <listitem><para>Takes an integer
- value. Controls the firewall mark of
- packets generated by this socket. This
- can be used in the firewall logic to
- filter packets from this socket. This
- sets the SO_MARK socket option. See
- <citerefentry><refentrytitle>iptables</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>PipeSize=</varname></term>
- <listitem><para>Takes an integer
- value. Controls the pipe buffer size
- of FIFOs configured in this socket
- unit. See
- <citerefentry><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>FreeBind=</varname></term>
- <listitem><para>Takes a boolean
- value. Controls whether the socket can
- be bound to non-local IP
- addresses. This is useful to configure
- sockets listening on specific IP
- addresses before those IP addresses
- are successfully configured on a
- network interface. This sets the
- IP_FREEBIND socket option. For
- robustness reasons it is recommended
- to use this option whenever you bind a
- socket to a specific IP
- address. Defaults to <option>false</option>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>TCPCongestion=</varname></term>
- <listitem><para>Takes a string
- value. Controls the TCP congestion
- algorithm used by this socket. Should
- be one of "westwood", "veno", "cubic",
- "lp" or any other available algorithm
- supported by the IP stack. This
- setting applies only to stream
- sockets.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ExecStartPre=</varname></term>
- <term><varname>ExecStartPost=</varname></term>
- <listitem><para>Takes one or more
- command lines, which are executed
- before (resp. after) the listening
- sockets/FIFOs are created and
- bound. The first token of the command
- line must be an absolute file name,
- then followed by arguments for the
- process. Multiple command lines may be
- specified following the same scheme as
- used for
- <varname>ExecStartPre=</varname> of
- service unit files.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ExecStopPre=</varname></term>
- <term><varname>ExecStopPost=</varname></term>
- <listitem><para>Additional commands
- that are executed before (resp. after)
- the listening sockets/FIFOs are closed
- and removed. Multiple command lines
- may be specified following the same
- scheme as used for
- <varname>ExecStartPre=</varname> of
- service unit files.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>TimeoutSec=</varname></term>
- <listitem><para>Configures the time to
- wait for the commands specified in
- <varname>ExecStartPre=</varname>,
- <varname>ExecStartPost=</varname>,
- <varname>ExecStopPre=</varname> and
- <varname>ExecStopPost=</varname> to
- finish. If a command does not exit
- within the configured time, the socket
- will be considered failed and be shut
- down again. All commands still running,
- will be terminated forcibly via
- SIGTERM, and after another delay of
- this time with SIGKILL. (See
- <option>KillMode=</option> below.)
- Takes a unit-less value in seconds, or
- a time span value such as "5min
- 20s". Pass 0 to disable the timeout
- logic. Defaults to
- 60s.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>KillMode=</varname></term>
- <listitem><para>Specifies how
- processes of this socket unit shall be
- killed. One of
- <option>control-group</option>,
- <option>process-group</option>,
- <option>process</option>,
- <option>none</option>.</para>
-
- <para>This option is mostly equivalent
- to the <option>KillMode=</option>
- option of service files. See
- <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Service=</varname></term>
- <listitem><para>Specifies the service
- unit name to activate on incoming
- traffic. This defaults to the service
- that bears the same name as the socket
- (ignoring the different suffixes). In
- most cases it should not be necessary
- to use this option.</para></listitem>
- </varlistentry>
-
- </variablelist>
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- </para>
- </refsect1>
+ <refentryinfo>
+ <title>systemd.socket</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd.socket</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd.socket</refname>
+ <refpurpose>Socket unit configuration</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename><replaceable>socket</replaceable>.socket</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>A unit configuration file whose name ends in
+ <literal>.socket</literal> encodes information about an IPC or
+ network socket or a file system FIFO controlled and supervised by
+ systemd, for socket-based activation.</para>
+
+ <para>This man page lists the configuration options specific to
+ this unit type. See
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for the common options of all unit configuration files. The common
+ configuration items are configured in the generic [Unit] and
+ [Install] sections. The socket specific configuration options are
+ configured in the [Socket] section.</para>
+
+ <para>Additional options are listed in
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ which define the execution environment the
+ <option>ExecStartPre=</option>, <option>ExecStartPost=</option>,
+ <option>ExecStopPre=</option> and <option>ExecStopPost=</option>
+ commands are executed in, and in
+ <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ which define the way the processes are terminated, and in
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ which configure resource control settings for the processes of the
+ socket.</para>
+
+ <para>For each socket file, a matching service file must exist,
+ describing the service to start on incoming traffic on the socket
+ (see
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more information about .service files). The name of the
+ .service unit is by default the same as the name of the .socket
+ unit, but can be altered with the <option>Service=</option> option
+ described below. Depending on the setting of the
+ <option>Accept=</option> option described below, this .service
+ unit must either be named like the .socket unit, but with the
+ suffix replaced, unless overridden with <option>Service=</option>;
+ or it must be a template unit named the same way. Example: a
+ socket file <filename>foo.socket</filename> needs a matching
+ service <filename>foo.service</filename> if
+ <option>Accept=false</option> is set. If
+ <option>Accept=true</option> is set, a service template file
+ <filename>foo@.service</filename> must exist from which services
+ are instantiated for each incoming connection.</para>
+
+ <para>Unless <varname>DefaultDependencies=</varname> is set to
+ <option>false</option>, socket units will implicitly have
+ dependencies of type <varname>Requires=</varname> and
+ <varname>After=</varname> on <filename>sysinit.target</filename>
+ as well as dependencies of type <varname>Conflicts=</varname> and
+ <varname>Before=</varname> on
+ <filename>shutdown.target</filename>. These ensure that socket
+ units pull in basic system initialization, and are terminated
+ cleanly prior to system shutdown. Only sockets involved with early
+ boot or late system shutdown should disable this option.</para>
+
+ <para>Socket units will have a <varname>Before=</varname>
+ dependency on the service which they trigger added implicitly. No
+ implicit <varname>WantedBy=</varname> or
+ <varname>RequiredBy=</varname> dependency from the socket to the
+ service is added. This means that the service may be started
+ without the socket, in which case it must be able to open sockets
+ by itself. To prevent this, an explicit
+ <varname>Requires=</varname> dependency may be added.</para>
+
+ <para>Socket units may be used to implement on-demand starting of
+ services, as well as parallelized starting of services. See the
+ blog stories linked at the end for an introduction.</para>
+
+ <para>Note that the daemon software configured for socket
+ activation with socket units needs to be able to accept sockets
+ from systemd, either via systemd's native socket passing interface
+ (see
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for details) or via the traditional
+ <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>-style
+ socket passing (i.e. sockets passed in via standard input and
+ output, using <varname>StandardInput=socket</varname> in the
+ service file).</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>Socket files must include a [Socket] section, which carries
+ information about the socket or FIFO it supervises. A number of
+ options that may be used in this section are shared with other
+ unit types. These options are documented in
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ The options specific to the [Socket] section of socket units are
+ the following:</para>
+
+ <variablelist class='unit-directives'>
+ <varlistentry>
+ <term><varname>ListenStream=</varname></term>
+ <term><varname>ListenDatagram=</varname></term>
+ <term><varname>ListenSequentialPacket=</varname></term>
+ <listitem><para>Specifies an address to listen on for a stream
+ (<constant>SOCK_STREAM</constant>), datagram
+ (<constant>SOCK_DGRAM</constant>), or sequential packet
+ (<constant>SOCK_SEQPACKET</constant>) socket, respectively.
+ The address can be written in various formats:</para>
+
+ <para>If the address starts with a slash
+ (<literal>/</literal>), it is read as file system socket in
+ the <constant>AF_UNIX</constant> socket family.</para>
+
+ <para>If the address starts with an at symbol
+ (<literal>@</literal>), it is read as abstract namespace
+ socket in the <constant>AF_UNIX</constant> family. The
+ <literal>@</literal> is replaced with a
+ <constant>NUL</constant> character before binding. For
+ details, see
+ <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+
+ <para>If the address string is a single number, it is read as
+ port number to listen on via IPv6. Depending on the value of
+ <varname>BindIPv6Only=</varname> (see below) this might result
+ in the service being available via both IPv6 and IPv4
+ (default) or just via IPv6.
+ </para>
+
+ <para>If the address string is a string in the format
+ v.w.x.y:z, it is read as IPv4 specifier for listening on an
+ address v.w.x.y on a port z.</para>
+
+ <para>If the address string is a string in the format [x]:y,
+ it is read as IPv6 address x on a port y. Note that this might
+ make the service available via IPv4, too, depending on the
+ <varname>BindIPv6Only=</varname> setting (see below).
+ </para>
+
+ <para>Note that <constant>SOCK_SEQPACKET</constant> (i.e.
+ <varname>ListenSequentialPacket=</varname>) is only available
+ for <constant>AF_UNIX</constant> sockets.
+ <constant>SOCK_STREAM</constant> (i.e.
+ <varname>ListenStream=</varname>) when used for IP sockets
+ refers to TCP sockets, <constant>SOCK_DGRAM</constant> (i.e.
+ <varname>ListenDatagram=</varname>) to UDP.</para>
+
+ <para>These options may be specified more than once in which
+ case incoming traffic on any of the sockets will trigger
+ service activation, and all listed sockets will be passed to
+ the service, regardless of whether there is incoming traffic
+ on them or not. If the empty string is assigned to any of
+ these options, the list of addresses to listen on is reset,
+ all prior uses of any of these options will have no
+ effect.</para>
+
+ <para>It is also possible to have more than one socket unit
+ for the same service when using <varname>Service=</varname>,
+ and the service will receive all the sockets configured in all
+ the socket units. Sockets configured in one unit are passed in
+ the order of configuration, but no ordering between socket
+ units is specified.</para>
+
+ <para>If an IP address is used here, it is often desirable to
+ listen on it before the interface it is configured on is up
+ and running, and even regardless of whether it will be up and
+ running at any point. To deal with this, it is recommended to
+ set the <varname>FreeBind=</varname> option described
+ below.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ListenFIFO=</varname></term>
+ <listitem><para>Specifies a file system FIFO to listen on.
+ This expects an absolute file system path as argument.
+ Behavior otherwise is very similar to the
+ <varname>ListenDatagram=</varname> directive
+ above.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ListenSpecial=</varname></term>
+ <listitem><para>Specifies a special file in the file system to
+ listen on. This expects an absolute file system path as
+ argument. Behavior otherwise is very similar to the
+ <varname>ListenFIFO=</varname> directive above. Use this to
+ open character device nodes as well as special files in
+ <filename>/proc</filename> and
+ <filename>/sys</filename>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ListenNetlink=</varname></term>
+ <listitem><para>Specifies a Netlink family to create a socket
+ for to listen on. This expects a short string referring to the
+ <constant>AF_NETLINK</constant> family name (such as
+ <varname>audit</varname> or <varname>kobject-uevent</varname>)
+ as argument, optionally suffixed by a whitespace followed by a
+ multicast group integer. Behavior otherwise is very similar to
+ the <varname>ListenDatagram=</varname> directive
+ above.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ListenMessageQueue=</varname></term>
+ <listitem><para>Specifies a POSIX message queue name to listen
+ on. This expects a valid message queue name (i.e. beginning
+ with /). Behavior otherwise is very similar to the
+ <varname>ListenFIFO=</varname> directive above. On Linux
+ message queue descriptors are actually file descriptors and
+ can be inherited between processes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>BindIPv6Only=</varname></term>
+ <listitem><para>Takes a one of <option>default</option>,
+ <option>both</option> or <option>ipv6-only</option>. Controls
+ the IPV6_V6ONLY socket option (see
+ <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details). If <option>both</option>, IPv6 sockets bound
+ will be accessible via both IPv4 and IPv6. If
+ <option>ipv6-only</option>, they will be accessible via IPv6
+ only. If <option>default</option> (which is the default,
+ surprise!), the system wide default setting is used, as
+ controlled by
+ <filename>/proc/sys/net/ipv6/bindv6only</filename>, which in
+ turn defaults to the equivalent of
+ <option>both</option>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Backlog=</varname></term>
+ <listitem><para>Takes an unsigned integer argument. Specifies
+ the number of connections to queue that have not been accepted
+ yet. This setting matters only for stream and sequential
+ packet sockets. See
+ <citerefentry><refentrytitle>listen</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details. Defaults to SOMAXCONN (128).</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>BindToDevice=</varname></term>
+ <listitem><para>Specifies a network interface name to bind
+ this socket to. If set, traffic will only be accepted from the
+ specified network interfaces. This controls the
+ SO_BINDTODEVICE socket option (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details). If this option is used, an automatic dependency
+ from this socket unit on the network interface device unit
+ (<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ is created.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SocketUser=</varname></term>
+ <term><varname>SocketGroup=</varname></term>
+
+ <listitem><para>Takes a UNIX user/group name. When specified,
+ all AF_UNIX sockets and FIFO nodes in the file system are
+ owned by the specified user and group. If unset (the default),
+ the nodes are owned by the root user/group (if run in system
+ context) or the invoking user/group (if run in user context).
+ If only a user is specified but no group, then the group is
+ derived from the user's default group.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SocketMode=</varname></term>
+ <listitem><para>If listening on a file system socket or FIFO,
+ this option specifies the file system access mode used when
+ creating the file node. Takes an access mode in octal
+ notation. Defaults to 0666.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>DirectoryMode=</varname></term>
+ <listitem><para>If listening on a file system socket or FIFO,
+ the parent directories are automatically created if needed.
+ This option specifies the file system access mode used when
+ creating these directories. Takes an access mode in octal
+ notation. Defaults to 0755.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Accept=</varname></term>
+ <listitem><para>Takes a boolean argument. If true, a service
+ instance is spawned for each incoming connection and only the
+ connection socket is passed to it. If false, all listening
+ sockets themselves are passed to the started service unit, and
+ only one service unit is spawned for all connections (also see
+ above). This value is ignored for datagram sockets and FIFOs
+ where a single service unit unconditionally handles all
+ incoming traffic. Defaults to <option>false</option>. For
+ performance reasons, it is recommended to write new daemons
+ only in a way that is suitable for
+ <option>Accept=false</option>. A daemon listening on an
+ <constant>AF_UNIX</constant> socket may, but does not need to,
+ call
+ <citerefentry><refentrytitle>close</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ on the received socket before exiting. However, it must not
+ unlink the socket from a file system. It should not invoke
+ <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ on sockets it got with <varname>Accept=false</varname>, but it
+ may do so for sockets it got with
+ <varname>Accept=true</varname> set. Setting
+ <varname>Accept=true</varname> is mostly useful to allow
+ daemons designed for usage with
+ <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ to work unmodified with systemd socket
+ activation.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MaxConnections=</varname></term>
+ <listitem><para>The maximum number of connections to
+ simultaneously run services instances for, when
+ <option>Accept=true</option> is set. If more concurrent
+ connections are coming in, they will be refused until at least
+ one existing connection is terminated. This setting has no
+ effect on sockets configured with
+ <option>Accept=false</option> or datagram sockets. Defaults to
+ 64.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>KeepAlive=</varname></term>
+ <listitem><para>Takes a boolean argument. If true, the TCP/IP
+ stack will send a keep alive message after 2h (depending on
+ the configuration of
+ <filename>/proc/sys/net/ipv4/tcp_keepalive_time</filename>)
+ for all TCP streams accepted on this socket. This controls the
+ SO_KEEPALIVE socket option (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ and the <ulink
+ url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+ Keepalive HOWTO</ulink> for details.) Defaults to
+ <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>KeepAliveTimeSec=</varname></term>
+ <listitem><para>Takes time (in seconds) as argument . The connection needs to remain
+ idle before TCP starts sending keepalive probes. This controls the TCP_KEEPIDLE
+ socket option (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ and the <ulink
+ url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+ Keepalive HOWTO</ulink> for details.)
+ Defaults value is 7200 seconds (2 hours).</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>KeepAliveIntervalSec=</varname></term>
+ <listitem><para>Takes time (in seconds) as argument between
+ individual keepalive probes, if the socket option SO_KEEPALIVE
+ has been set on this socket seconds as argument. This controls
+ the TCP_KEEPINTVL socket option (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ and the <ulink
+ url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+ Keepalive HOWTO</ulink> for details.) Defaults value is 75
+ seconds.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>KeepAliveProbes=</varname></term>
+ <listitem><para>Takes integer as argument. It's the number of
+ unacknowledged probes to send before considering the
+ connection dead and notifying the application layer. This
+ controls the TCP_KEEPCNT socket option (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ and the <ulink
+ url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+ Keepalive HOWTO</ulink> for details.) Defaults value is
+ 9.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>NoDelay=</varname></term>
+ <listitem><para>Takes a boolean argument. TCP Nagle's
+ algorithm works by combining a number of small outgoing
+ messages, and sending them all at once. This controls the
+ TCP_NODELAY socket option (see
+ <citerefentry><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ Defaults to <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Priority=</varname></term>
+ <listitem><para>Takes an integer argument controlling the
+ priority for all traffic sent from this socket. This controls
+ the SO_PRIORITY socket option (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.).</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>DeferAcceptSec=</varname></term>
+
+ <listitem><para>Takes time (in seconds) as argument. If set,
+ the listening process will be awakened only when data arrives
+ on the socket, and not immediately when connection is
+ established. When this option is set, the
+ <constant>TCP_DEFER_ACCEPT</constant> socket option will be
+ used (see
+ <citerefentry><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
+ and the kernel will ignore initial ACK packets without any
+ data. The argument specifies the approximate amount of time
+ the kernel should wait for incoming data before falling back
+ to the normal behaviour of honouring empty ACK packets. This
+ option is beneficial for protocols where the client sends the
+ data first (e.g. HTTP, in contrast to SMTP), because the
+ server process will not be woken up unnecessarily before it
+ can take any action.
+ </para>
+
+ <para>If the client also uses the
+ <constant>TCP_DEFER_ACCEPT</constant> option, the latency of
+ the initial connection may be reduced, because the kernel will
+ send data in the final packet establishing the connection (the
+ third packet in the "three-way handshake").</para>
+
+ <para>Disabled by default.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ReceiveBuffer=</varname></term>
+ <term><varname>SendBuffer=</varname></term>
+ <listitem><para>Takes an integer argument controlling the
+ receive or send buffer sizes of this socket, respectively.
+ This controls the SO_RCVBUF and SO_SNDBUF socket options (see
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.). The usual suffixes K, M, G are supported and
+ are understood to the base of 1024.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IPTOS=</varname></term>
+ <listitem><para>Takes an integer argument controlling the IP
+ Type-Of-Service field for packets generated from this socket.
+ This controls the IP_TOS socket option (see
+ <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.). Either a numeric string or one of
+ <option>low-delay</option>, <option>throughput</option>,
+ <option>reliability</option> or <option>low-cost</option> may
+ be specified.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IPTTL=</varname></term>
+ <listitem><para>Takes an integer argument controlling the IPv4
+ Time-To-Live/IPv6 Hop-Count field for packets generated from
+ this socket. This sets the IP_TTL/IPV6_UNICAST_HOPS socket
+ options (see
+ <citerefentry><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.)</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Mark=</varname></term>
+ <listitem><para>Takes an integer value. Controls the firewall
+ mark of packets generated by this socket. This can be used in
+ the firewall logic to filter packets from this socket. This
+ sets the SO_MARK socket option. See
+ <citerefentry><refentrytitle>iptables</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ReusePort=</varname></term>
+ <listitem><para>Takes a boolean value. If true, allows
+ multiple
+ <citerefentry><refentrytitle>bind</refentrytitle><manvolnum>2</manvolnum></citerefentry>s
+ to this TCP or UDP port. This controls the SO_REUSEPORT socket
+ option. See
+ <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SmackLabel=</varname></term>
+ <term><varname>SmackLabelIPIn=</varname></term>
+ <term><varname>SmackLabelIPOut=</varname></term>
+ <listitem><para>Takes a string value. Controls the extended
+ attributes <literal>security.SMACK64</literal>,
+ <literal>security.SMACK64IPIN</literal> and
+ <literal>security.SMACK64IPOUT</literal>, respectively, i.e.
+ the security label of the FIFO, or the security label for the
+ incoming or outgoing connections of the socket, respectively.
+ See <ulink
+ url="https://www.kernel.org/doc/Documentation/security/Smack.txt">Smack.txt</ulink>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SELinuxContextFromNet=</varname></term>
+ <listitem><para>Takes a boolean argument. When true, systemd
+ will attempt to figure out the SELinux label used for the
+ instantiated service from the information handed by the peer
+ over the network. Note that only the security level is used
+ from the information provided by the peer. Other parts of the
+ resulting SELinux context originate from either the target
+ binary that is effectively triggered by socket unit or from
+ the value of the <varname>SELinuxContext=</varname> option.
+ This configuration option only affects sockets with
+ <varname>Accept=</varname> mode set to
+ <literal>true</literal>. Also note that this option is useful
+ only when MLS/MCS SELinux policy is deployed. Defaults to
+ <literal>false</literal>. </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>PipeSize=</varname></term>
+ <listitem><para>Takes a size in bytes. Controls the pipe
+ buffer size of FIFOs configured in this socket unit. See
+ <citerefentry><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details. The usual suffixes K, M, G are supported and are
+ understood to the base of 1024.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>MessageQueueMaxMessages=</varname>,
+ <varname>MessageQueueMessageSize=</varname></term>
+ <listitem><para>These two settings take integer values and
+ control the mq_maxmsg field or the mq_msgsize field,
+ respectively, when creating the message queue. Note that
+ either none or both of these variables need to be set. See
+ <citerefentry><refentrytitle>mq_setattr</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>FreeBind=</varname></term>
+ <listitem><para>Takes a boolean value. Controls whether the
+ socket can be bound to non-local IP addresses. This is useful
+ to configure sockets listening on specific IP addresses before
+ those IP addresses are successfully configured on a network
+ interface. This sets the IP_FREEBIND socket option. For
+ robustness reasons it is recommended to use this option
+ whenever you bind a socket to a specific IP address. Defaults
+ to <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Transparent=</varname></term>
+ <listitem><para>Takes a boolean value. Controls the
+ IP_TRANSPARENT socket option. Defaults to
+ <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Broadcast=</varname></term>
+ <listitem><para>Takes a boolean value. This controls the
+ SO_BROADCAST socket option, which allows broadcast datagrams
+ to be sent from this socket. Defaults to
+ <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>PassCredentials=</varname></term>
+ <listitem><para>Takes a boolean value. This controls the
+ SO_PASSCRED socket option, which allows
+ <constant>AF_UNIX</constant> sockets to receive the
+ credentials of the sending process in an ancillary message.
+ Defaults to <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>PassSecurity=</varname></term>
+ <listitem><para>Takes a boolean value. This controls the
+ SO_PASSSEC socket option, which allows
+ <constant>AF_UNIX</constant> sockets to receive the security
+ context of the sending process in an ancillary message.
+ Defaults to <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>TCPCongestion=</varname></term>
+ <listitem><para>Takes a string value. Controls the TCP
+ congestion algorithm used by this socket. Should be one of
+ "westwood", "veno", "cubic", "lp" or any other available
+ algorithm supported by the IP stack. This setting applies only
+ to stream sockets.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ExecStartPre=</varname></term>
+ <term><varname>ExecStartPost=</varname></term>
+ <listitem><para>Takes one or more command lines, which are
+ executed before or after the listening sockets/FIFOs are
+ created and bound, respectively. The first token of the
+ command line must be an absolute filename, then followed by
+ arguments for the process. Multiple command lines may be
+ specified following the same scheme as used for
+ <varname>ExecStartPre=</varname> of service unit
+ files.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ExecStopPre=</varname></term>
+ <term><varname>ExecStopPost=</varname></term>
+ <listitem><para>Additional commands that are executed before
+ or after the listening sockets/FIFOs are closed and removed,
+ respectively. Multiple command lines may be specified
+ following the same scheme as used for
+ <varname>ExecStartPre=</varname> of service unit
+ files.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>TimeoutSec=</varname></term>
+ <listitem><para>Configures the time to wait for the commands
+ specified in <varname>ExecStartPre=</varname>,
+ <varname>ExecStartPost=</varname>,
+ <varname>ExecStopPre=</varname> and
+ <varname>ExecStopPost=</varname> to finish. If a command does
+ not exit within the configured time, the socket will be
+ considered failed and be shut down again. All commands still
+ running will be terminated forcibly via
+ <constant>SIGTERM</constant>, and after another delay of this
+ time with <constant>SIGKILL</constant>. (See
+ <option>KillMode=</option> in
+ <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
+ Takes a unit-less value in seconds, or a time span value such
+ as "5min 20s". Pass <literal>0</literal> to disable the
+ timeout logic. Defaults to
+ <varname>DefaultTimeoutStartSec=</varname> from the manager
+ configuration file (see
+ <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Service=</varname></term>
+ <listitem><para>Specifies the service unit name to activate on
+ incoming traffic. This setting is only allowed for sockets
+ with <varname>Accept=no</varname>. It defaults to the service
+ that bears the same name as the socket (with the suffix
+ replaced). In most cases, it should not be necessary to use
+ this option.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RemoveOnStop=</varname></term>
+ <listitem><para>Takes a boolean argument. If enabled, any file
+ nodes created by this socket unit are removed when it is
+ stopped. This applies to AF_UNIX sockets in the file system,
+ POSIX message queues, FIFOs, as well as any symlinks to them
+ configured with <varname>Symlinks=</varname>. Normally, it
+ should not be necessary to use this option, and is not
+ recommended as services might continue to run after the socket
+ unit has been terminated and it should still be possible to
+ communicate with them via their file system node. Defaults to
+ off.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Symlinks=</varname></term>
+ <listitem><para>Takes a list of file system paths. The
+ specified paths will be created as symlinks to the AF_UNIX
+ socket path or FIFO path of this socket unit. If this setting
+ is used, only one AF_UNIX socket in the file system or one
+ FIFO may be configured for the socket unit. Use this option to
+ manage one or more symlinked alias names for a socket, binding
+ their lifecycle together. Defaults to the empty
+ list.</para></listitem>
+ </varlistentry>
+
+ </variablelist>
+
+ <para>Check
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more settings.</para>
+
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ </para>
+
+ <para>
+ For more extensive descriptions see the "systemd for Developers" series:
+ <ulink url="http://0pointer.de/blog/projects/socket-activation.html">Socket Activation</ulink>,
+ <ulink url="http://0pointer.de/blog/projects/socket-activation2.html">Socket Activation, part II</ulink>,
+ <ulink url="http://0pointer.de/blog/projects/inetd.html">Converting inetd Services</ulink>,
+ <ulink url="http://0pointer.de/blog/projects/socket-activated-containers.html">Socket Activated Internet Services and OS Containers</ulink>.
+ </para>
+ </refsect1>
</refentry>
~ianmdlvl / elogind.git / blobdiff