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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | EXAMPLES | SEE ALSO | COLOPHON |
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SYSTEMD-SOCKET-PROXYD(8) systemd-socket-proxyd SYSTEMD-SOCKET-PROXYD(8)
systemd-socket-proxyd - Bidirectionally proxy local sockets to
another (possibly remote) socket
systemd-socket-proxyd [OPTIONS...] HOST:PORT
systemd-socket-proxyd [OPTIONS...] UNIX-DOMAIN-SOCKET-PATH
systemd-socket-proxyd 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.
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.
This utility's behavior is similar to socat(1). The main
differences for systemd-socket-proxyd are support for socket
activation with "Accept=no" and an event-driven design that scales
better with the number of connections.
Note that systemd-socket-proxyd will not forward socket side
channel information, i.e. will not forward SCM_RIGHTS,
SCM_CREDENTIALS, SCM_SECURITY, SO_PEERCRED, SO_PEERPIDFD,
SO_PEERSEC, SO_PEERGROUPS and similar.
The following options are understood:
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
--connections-max=, -c
Sets the maximum number of simultaneous connections, defaults
to 256. If the limit of concurrent connections is reached
further connections will be refused.
Added in version 233.
--exit-idle-time=
Sets the time before exiting when there are no connections,
defaults to infinity. Takes a unit-less value in seconds, or a
time span value such as "5min 20s".
Added in version 246.
On success, 0 is returned, a non-zero failure code otherwise.
Simple Example
Use two services with a dependency and no namespace isolation.
Example 1. proxy-to-nginx.socket
[Socket]
ListenStream=80
[Install]
WantedBy=sockets.target
Example 2. proxy-to-nginx.service
[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
Example 3. nginx.conf
[...]
server {
listen unix:/run/nginx/socket;
[...]
Example 4. Enabling the proxy
# systemctl enable --now proxy-to-nginx.socket
$ curl http://localhost:80/
If nginx.service has StopWhenUnneeded= set, then passing
--exit-idle-time= to systemd-socket-proxyd allows both services to
stop during idle periods.
Namespace Example
Similar as above, but runs the socket proxy and the main service
in the same private namespace, assuming that nginx.service has
PrivateTmp= and PrivateNetwork= set, too.
Example 5. proxy-to-nginx.socket
[Socket]
ListenStream=80
[Install]
WantedBy=sockets.target
Example 6. proxy-to-nginx.service
[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
Example 7. nginx.conf
[...]
server {
listen 8080;
[...]
Example 8. Enabling the proxy
# systemctl enable --now proxy-to-nginx.socket
$ curl http://localhost:80/
systemd(1), systemd.socket(5), systemd.service(5), systemctl(1),
socat(1), nginx(1), curl(1)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 258~rc2 SYSTEMD-SOCKET-PROXYD(8)
Pages that refer to this page: systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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