Manual: systemd-ssh-proxy

SYSTEMD-SSH-PROXY(1)				      systemd-ssh-proxy					SYSTEMD-SSH-PROXY(1)

NAME
       systemd-ssh-proxy - SSH client plugin for connecting to AF_VSOCK and AF_UNIX sockets

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

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

DESCRIPTION
       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/* unix%* vsock/* vsock%* vsock-mux/* 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.

       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 do not allow
       direct AF_VSOCK communication between the host and guests, and provide their own multiplexer over AF_UNIX sockets.
       See cloud-hypervisor VSOCK support[1] and Using the Firecracker Virtio-vsock Device[2]. Note that "%" can be used as
       a separator instead of "/" to be compatible with tools like "scp" and "rsync".

       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 or VM guest, and
       systemd-ssh-proxy is run on the host, in order to connect to the container or VM guest.

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

EXAMPLES
       Example 1. Talk to a local VM with CID 4711

	   ssh vsock/4711

       Example 2. Talk to a VM guest hosted with cloud-hypervisor/firecracker

	   ssh vsock-mux/run/vm-1234.sock

       Example 3. Talk to the local host via ssh

	   ssh .host

       or equivalent:

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

       Example 4. Copy local 'foo' file to a local VM with CID 1348

	   scp foo vsock%1348:

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

NOTES
	1. cloud-hypervisor VSOCK support
	   https://github.com/cloud-hypervisor/cloud-hypervisor/blob/main/docs/vsock.md

	2. Using the Firecracker Virtio-vsock Device
	   https://github.com/firecracker-microvm/firecracker/blob/main/docs/vsock.md

systemd 259.5												SYSTEMD-SSH-PROXY(1)