mirror of
https://github.com/AuxXxilium/eudev.git
synced 2024-12-22 23:36:40 +07:00
cebf8b2092
Hi, attached path extends socket configurables with another knob - TCP Congestion Avoidance selection. Linux implements handful of those, useful in various situations. For example, TCP Low Priority may be used by FTP service to gracefully yield bandwidth for more important TCP/IP streams. Until recently TCP_CONGESTION was Linux-specific, recently FreeBSD 8 and OpenSolaris gained compatible support.
536 lines
30 KiB
XML
536 lines
30 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
|
|
|
<!--
|
|
This file is part of systemd.
|
|
|
|
Copyright 2010 Lennart Poettering
|
|
|
|
systemd is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
systemd is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
|
-->
|
|
|
|
<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>
|
|
</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>
|
|
|
|
</refentry>
|