It seems since autossh changed their syntax, I am a bit overstrained in establishing a reverse ssh tunnel via autossh with my server. This is the script I am trying to run:
autossh -M 20000 -f -N -R 17999:localhost:22 user@server -pXXXX -i id_rsa
Where 20000 is the monitor port (that autossh seems to need now), 17999 ist the port on my server autossh should listen to, 22 is the open port on my local machine and XXXX is the open SSH-port on my server. But nevertheless, my journalctl shows this:
autossh: ssh exited with error status 255; restarting ssh
In a row. Where did I got wrong? The pure SSH equivalent I am using is
ssh -fNC -R 17999:localhost:22 user@server -pXXXX -i id_rsa
And this works just fine.