systemd-ssh-proxy - Man Page

Host unix/* vsock/*
    ProxyCommand /usr/lib/systemd/systemd-ssh-proxy %h %p
    ProxyUseFdpass yes

/usr/lib/systemd/systemd-ssh-proxy [ADDRESS] [PORT]

systemd-ssh-proxy is a small "proxy" plugin for the ssh(1) tool that allows connecting to AF_UNIX and AF_VSOCK sockets. It implements the interface defined by ssh's ProxyCommand configuration option. It's supposed to be used with an ssh_config(5) configuration fragment like the following:

Host unix/* vsock/*
    ProxyCommand /usr/lib/systemd/systemd-ssh-proxy %h %p
    ProxyUseFdpass yes
    CheckHostIP no

Host .host
    ProxyCommand /usr/lib/systemd/systemd-ssh-proxy unix/run/ssh-unix-local/socket %p
    ProxyUseFdpass yes
    CheckHostIP no

A configuration fragment along these lines is by default installed into /etc/ssh/ssh_config.d/20-systemd-ssh-proxy.conf.in.

With this in place, SSH connections to host string "unix/" followed by an absolute AF_UNIX file system path to a socket will be directed to the specified socket, which must be of type SOCK_STREAM. Similar, SSH connections to "vsock/" followed by an AF_VSOCK CID will result in an SSH connection made to that CID. Moreover connecting to ".host" will connect to the local host via SSH, without involving networking.

This tool is supposed to be used together with systemd-ssh-generator(8) which when run inside a VM or container will bind SSH to suitable addresses. systemd-ssh-generator is supposed to run in the container of VM guest, and systemd-ssh-proxy is run on the host, in order to connect to the container or VM guest.

On success, 0 is returned, a non-zero failure code otherwise.

Example 1. Talk to a local VM with CID 4711

ssh vsock/4711

Example 2. Talk to the local host via ssh

ssh .host

or equivalent:

ssh unix/run/ssh-unix-local/socket

systemd(1), systemd-ssh-generator(8), vsock(7), unix(7), ssh(1), sshd(8)

systemd.directives(7), systemd.index(7), systemd-ssh-generator(8).