Manual: systemd-ssh-generator

SYSTEMD-SSH-GENERATOR(8)			    systemd-ssh-generator			    SYSTEMD-SSH-GENERATOR(8)

NAME
       systemd-ssh-generator - Generator for binding a socket-activated SSH server to local AF_VSOCK and AF_UNIX sockets

SYNOPSIS
       /usr/lib/systemd/system-generators/systemd-ssh-generator

DESCRIPTION
       systemd-ssh-generator binds a socket-activated SSH server to local AF_VSOCK and AF_UNIX sockets under certain
       conditions. It only has an effect if the sshd(8) binary is installed. Specifically, it does the following:

       •   If invoked in a VM with AF_VSOCK support, a socket-activated SSH per-connection service is bound to AF_VSOCK port
	   22.

       •   If invoked in a container environment with a writable directory /run/host/unix-export/ pre-mounted it binds SSH
	   to an AF_UNIX socket /run/host/unix-export/ssh. The assumption is that this directory is bind mounted to the host
	   side as well, and can be used to connect to the container from there. See Container Interface[1] for more
	   information about this interface.

       •   A local AF_UNIX socket /run/ssh-unix-local/socket is also bound, unconditionally. This may be used for SSH
	   communication from the host to itself, without involving networking, for example to traverse security boundaries
	   safely and with secure authentication.

       •   Additional AF_UNIX and AF_VSOCK sockets are optionally bound, based on the systemd.ssh_listen= kernel command
	   line option or the ssh.listen system credential (see below).

       See systemd-ssh-proxy(1) for details on how to connect to these sockets via the ssh client.

       The ssh.authorized_keys.root credential can be used to allow specific public keys to log in over SSH. See
       systemd.system-credentials(7) for more information.

       The generator will use a packaged sshd@.service service template file if one exists, and otherwise generate a
       suitable service template file.

       systemd-ssh-generator implements systemd.generator(7).

KERNEL COMMAND LINE
       systemd-ssh-generator understands the following kernel-command-line(7) parameters:

       systemd.ssh_auto=
	   This option takes an optional boolean argument, and defaults to yes. If enabled, the automatic binding to the
	   AF_VSOCK and AF_UNIX sockets listed above is done. If disable, this is not done, except for those explicitly
	   requested via systemd.ssh_listen= on the kernel command line or via the ssh.listen system credential.

	   Added in version 256.

       systemd.ssh_listen=
	   This option configures an additional socket to bind SSH to. It may be used multiple times to bind multiple
	   sockets. The syntax should follow the one of ListenStream=, see systemd.socket(5) for details. This functionality
	   supports all socket families systemd(1) supports, including AF_INET and AF_INET6.

	   Added in version 256.

CREDENTIALS
       systemd-ssh-generator supports the system credentials logic. The following credentials are used when passed in:

       ssh.listen
	   This credential should be a text file, with each line referencing one additional socket to bind SSH to. The
	   syntax should follow the one of ListenStream=, see systemd.socket(5) for details. This functionality supports all
	   socket families systemd supports, including AF_INET and AF_INET6.

	   Added in version 256.

       ssh.ephemeral-authorized_keys-all
	   Provides additional public keys, given in the customary authorized_keys format, for all users, for incoming
	   connections via the generated AF_VSOCK and AF_UNIX socket units.

	   The intended use of this is for a host system (in either VM or container configurations) to generate a keypair
	   and inject the public key into the guest, using the private key to connect to any user account on the guest via
	   ssh, without further authentication.

	   Added in version 256.

SEE ALSO
       systemd(1), kernel-command-line(7), systemd.system-credentials(7), vsock(7), unix(7), ssh(1), sshd(8)

NOTES
	1. Container Interface
	   https://systemd.io/CONTAINER_INTERFACE

systemd 259.5											    SYSTEMD-SSH-GENERATOR(8)