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Keep harden_ssh working when sshd is socket-activated - #860
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On Ubuntu 24.04 openssh-server is socket-activated. The dist-upgrade that runs earlier in the installer upgrades openssh-server, and that package's postinst only restarts ssh.socket. Restarting the socket stops ssh.service, and systemd removes the unit's RuntimeDirectory, /run/sshd, with it. The session running bbb-install survives (KillMode=process), so when harden_ssh later runs `sshd -t` there is no daemon and no /run/sshd, and sshd aborts with "Missing privilege separation directory: /run/sshd". harden_ssh then removes the hardening file and exits the installer with status 1, before the LTI/Greenlight, ImageMagick policy and final bbb-conf --check steps. Create /run/sshd before validating. systemd recreates and removes the directory on service start and stop anyway, so this is harmless when the daemon is already running. The restart fallback had the same blind spot: sshd.service is only an alias of ssh.service, and the alias is not installed while ssh.socket is what is enabled, so `systemctl restart sshd` fails there with "Unit sshd.service not found". The unit has been ssh.service on every Ubuntu release the installer supports. `systemctl try-restart ssh.service` restarts a running daemon and is a no-op for an idle socket-activated one, whose next connection starts it with the new config. Reproduced and verified on a fresh 24.04 droplet installing 4.0.
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On Ubuntu 24.04 openssh-server is socket-activated. The dist-upgrade that runs earlier in the installer upgrades openssh-server, and that package's postinst only restarts ssh.socket. Restarting the socket stops ssh.service, and systemd removes the unit's RuntimeDirectory, /run/sshd, with it. The session running bbb-install survives (KillMode=process), so when harden_ssh later runs
sshd -tthere is no daemon and no /run/sshd, and sshd aborts with "Missing privilege separation directory: /run/sshd". harden_ssh then removes the hardening file and exits the installer with status 1, before the LTI/Greenlight, ImageMagick policy and final bbb-conf --check steps.Create /run/sshd before validating. systemd recreates and removes the directory on service start and stop anyway, so this is harmless when the daemon is already running.
The restart fallback had the same blind spot: sshd.service is only an alias of ssh.service, and the alias is not installed while ssh.socket is what is enabled, so
systemctl restart sshdfails there with "Unit sshd.service not found". The unit has been ssh.service on every Ubuntu release the installer supports.systemctl try-restart ssh.servicerestarts a running daemon and is a no-op for an idle socket-activated one, whose next connection starts it with the new config.Reproduced and verified on a fresh 24.04 droplet installing 4.0.