systemd 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 socat1. 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: --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. --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. --proxy-protocol= Uses the PROXY protocol to communicate with the server. This allows an appropriately configured server to know the real client IP address. Takes the version of the PROXY protocol used, and only supports v1 for now. Default is not to use a PROXY protocol. On success, 0 is returned, a non-zero failure code otherwise. Use two services with a dependency and no namespace isolation. If nginx.service has StopWhenUnneeded= set, then passing --exit-idle-time= to systemd-socket-proxyd allows both services to stop during idle periods. 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. systemd-socket-proxyd and nginx using the PROXY protocol systemd1 systemd.socket5 systemd.service5 systemctl1 socat1 nginx1 curl1 PROXY protocol specification nginx: Accepting the PROXY Protocol