<?xml version="1.0"?> <!--*-nxml-*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> <refentry id="systemd-socket-proxyd" xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>systemd-socket-proxyd</title> <productname>systemd</productname> </refentryinfo> <refmeta> <refentrytitle>systemd-socket-proxyd</refentrytitle> <manvolnum>8</manvolnum> </refmeta> <refnamediv> <refname>systemd-socket-proxyd</refname> <refpurpose>Bidirectionally proxy local sockets to another (possibly remote) socket</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>systemd-socket-proxyd</command> <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg> <arg choice="plain"><replaceable>HOST</replaceable>:<replaceable>PORT</replaceable></arg> </cmdsynopsis> <cmdsynopsis> <command>systemd-socket-proxyd</command> <arg choice="opt" rep="repeat"><replaceable>OPTIONS</replaceable></arg> <arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable> </arg> </cmdsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para> <command>systemd-socket-proxyd</command> is a generic socket-activated network socket forwarder proxy daemon for IPv4, IPv6 and UNIX stream sockets. It may be used to bi-directionally forward traffic from a local listening socket to a local or remote destination socket.</para> <para>One use of this tool is to provide socket activation support for services that do not natively support socket activation. On behalf of the service to activate, the proxy inherits the socket from systemd, accepts each client connection, opens a connection to a configured server for each client, and then bidirectionally forwards data between the two.</para> <para>This utility's behavior is similar to <citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The main differences for <command>systemd-socket-proxyd</command> are support for socket activation with <literal>Accept=no</literal> and an event-driven design that scales better with the number of connections.</para> <para>Note that <command>systemd-socket-proxyd</command> will not forward socket side channel information, i.e. will not forward <constant>SCM_RIGHTS</constant>, <constant>SCM_CREDENTIALS</constant>, <constant>SCM_SECURITY</constant>, <constant>SO_PEERCRED</constant>, <constant>SO_PEERPIDFD</constant>, <constant>SO_PEERSEC</constant>, <constant>SO_PEERGROUPS</constant> and similar.</para> </refsect1> <refsect1> <title>Options</title> <para>The following options are understood:</para> <variablelist> <xi:include href="standard-options.xml" xpointer="help" /> <xi:include href="standard-options.xml" xpointer="version" /> <varlistentry> <term><option>--connections-max=</option></term> <term><option>-c</option></term> <listitem><para>Sets the maximum number of simultaneous connections, defaults to 256. If the limit of concurrent connections is reached further connections will be refused.</para> <xi:include href="version-info.xml" xpointer="v233"/></listitem> </varlistentry> <varlistentry> <term><option>--exit-idle-time=</option></term> <listitem><para>Sets the time before exiting when there are no connections, defaults to <constant>infinity</constant>. Takes a unit-less value in seconds, or a time span value such as <literal>5min 20s</literal>.</para> <xi:include href="version-info.xml" xpointer="v246"/></listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>Exit status</title> <para>On success, 0 is returned, a non-zero failure code otherwise.</para> </refsect1> <refsect1> <title>Examples</title> <refsect2> <title>Simple Example</title> <para>Use two services with a dependency and no namespace isolation.</para> <example> <title>proxy-to-nginx.socket</title> <programlisting><![CDATA[[Socket] ListenStream=80 [Install] WantedBy=sockets.target]]></programlisting> </example> <example> <title>proxy-to-nginx.service</title> <programlisting><![CDATA[[Unit] Requires=nginx.service After=nginx.service Requires=proxy-to-nginx.socket After=proxy-to-nginx.socket [Service] Type=notify ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket PrivateTmp=yes PrivateNetwork=yes]]></programlisting> </example> <example> <title>nginx.conf</title> <programlisting> <![CDATA[[…] server { listen unix:/run/nginx/socket; […]]]> </programlisting> </example> <example> <title>Enabling the proxy</title> <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket $ curl http://localhost:80/]]></programlisting> </example> <para>If <filename>nginx.service</filename> has <varname>StopWhenUnneeded=</varname> set, then passing <option>--exit-idle-time=</option> to <command>systemd-socket-proxyd</command> allows both services to stop during idle periods.</para> </refsect2> <refsect2> <title>Namespace Example</title> <para>Similar as above, but runs the socket proxy and the main service in the same private namespace, assuming that <filename>nginx.service</filename> has <varname>PrivateTmp=</varname> and <varname>PrivateNetwork=</varname> set, too.</para> <example> <title>proxy-to-nginx.socket</title> <programlisting><![CDATA[[Socket] ListenStream=80 [Install] WantedBy=sockets.target]]></programlisting> </example> <example> <title>proxy-to-nginx.service</title> <programlisting><![CDATA[[Unit] Requires=nginx.service After=nginx.service Requires=proxy-to-nginx.socket After=proxy-to-nginx.socket JoinsNamespaceOf=nginx.service [Service] Type=notify ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080 PrivateTmp=yes PrivateNetwork=yes]]></programlisting> </example> <example> <title>nginx.conf</title> <programlisting><![CDATA[[…] server { listen 8080; […]]]></programlisting> </example> <example> <title>Enabling the proxy</title> <programlisting><![CDATA[# systemctl enable --now proxy-to-nginx.socket $ curl http://localhost:80/]]></programlisting> </example> </refsect2> </refsect1> <refsect1> <title>See Also</title> <para><simplelist type="inline"> <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> <member><citerefentry project='die-net'><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> <member><citerefentry project='die-net'><refentrytitle>nginx</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> <member><citerefentry project='die-net'><refentrytitle>curl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> </simplelist></para> </refsect1> </refentry>