systemd systemd-ssh-proxy 1 systemd-ssh-proxy SSH client plugin for connecting to AF_VSOCK and AF_UNIX sockets Host unix/* vsock/* vsock-mux/* 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 ssh1 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_config5 configuration fragment like the following: Host unix/* vsock/* vsock-mux/* 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. vsock-mux/ followed by an absolute AF_UNIX file system path to a socket is similar but for cloud-hypervisor/firecracker which don't allow direct AF_VSOCK communication between the host and guests, and provide their own multiplexer over AF_UNIX sockets. See cloud-hypervisor VSOCK support and Using the Firecracker Virtio-vsock Device. 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-generator8 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. ssh vsock/4711 ssh vsock-mux/run/vm-1234.sock ssh .host or equivalent: ssh unix/run/ssh-unix-local/socket systemd1 systemd-ssh-generator8 vsock7 unix7 ssh1 sshd8