This new passive target is supposed to be pulled in by SSH
implementations and should be reached when remote SSH access is
possible. The idea is that this target can be used as indicator for
other components to determine if and when SSH access is possible.
One specific usecase for this is the new sd_notify() logic in PID 1 that
sends its own supervisor notifications whenever target units are
reached. This can be used to precisely schedule SSH connections from
host to VM/container, or just to identify systems where SSH is even
available.
Tighten our VM check: whether we run in a VM is not enough to do
AF_VSOCK. We also need to check if we are run in a container, because if
we run in a container inside a VM then we should *not* do the AF_VSOCK
stuff, but leave the port free for the VM itself.
As discussed here:
https://github.com/systemd/systemd/pull/31544#issuecomment-1971455401
20-systemd-ssh-generator.conf expands SSHCONFDIR, which is bogus when we
build with -Dsshconfdir=no. Similarly, avoid expanding SSHDCONFDIR in
20-systemd-userdb.conf when building with -Dsshconfdir=no.
Follow-up 6c7fc5d5f2.
This adds a tiny binary that is hooked into SSH client config via
ProxyCommand and which simply connects to an AF_UNIX or AF_VSOCK socket
of choice.
The syntax is as simple as this:
ssh unix/some/path # (this connects to AF_UNIX socket /some/path)
or:
ssh vsock/4711
I used "/" as separator of the protocol ID and the value since ":" is
already taken by SSH itself when doing sftp. And "@" is already taken
for separating the user name.
Mike Yuan
Frantisek Sumsal
Luca Boccassi
Lennart Poettering
Sam Leonard