● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Tue 2017-04-04 09:59:25 CEST; 31min ago
  Process: 24419 ExecStart=/usr/sbin/sshd -D $SSHD_OPTS (code=exited, status=255)
 Main PID: 24419 (code=exited, status=255)

Apr 04 09:59:25systemd[1]: Starting OpenBSD Secure Shell server...
Apr 04 09:59:25  systemd[1]: ssh.service: Main process exited, code=exited, status=255/n/a
Apr 04 09:59:25  systemd[1]: Failed to start OpenBSD Secure Shell server.
Apr 04 09:59:25  systemd[1]: ssh.service: Unit entered failed state.
Apr 04 09:59:25  systemd[1]: ssh.service: Failed with result 'exit-code'.