systemd-ssh-proxy(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | EXIT STATUS | EXAMPLES | SEE ALSO | NOTES | COLOPHON

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

NAME         top

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

SYNOPSIS         top

       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         top

       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         top

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

EXAMPLES         top

       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         top

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

NOTES         top

        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

COLOPHON         top

       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
       man-pages@man7.org

systemd 258~rc2                                      SYSTEMD-SSH-PROXY(1)

Pages that refer to this page: systemd.directives(7)systemd.index(7)systemd-ssh-generator(8)