F. Hauri - Give Up GitHub's questions

This is question is an upgrade attempt of Find out which ssh key was used to access an account -- Some scripts for proper installation

Where I

• use rsyslog to generate separated log file, readable by group user,
• modify .bashrc for adding a $SSH_USER_KEY in user environment.

Unfortunately on systems using systemd and journalctl I have to manually install rsyslog which are no more installed by default.

So yes, if I install rsyslog package, I could resolve my problem, my scripts will run again but,

I wonder if there could exist some more appropriated (systemd) way for permitting user to see the hash of key used for the last connection.