$ ssh -p 22 localhost Welcome to Ubuntu 16.04.5 LTS (GNU/Linux 4.15.0-33-generic x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/advantage 2 packages can be updated. 0 updates are security updates. New release '18.04.1 LTS' available. Run 'do-release-upgrade' to upgrade to it. *** System restart required *** You have new mail. Last login: Wed Sep 12 10:40:51 2018 from 127.0.0.1 user@hostname:~$ sudo su - [sudo] password for user: root@hostname:~# #### Sep 10 17:39:01 user CRON[28734]: pam_unix(cron:session): session opened for user root by (uid=0) Sep 10 17:39:01 user CRON[28734]: pam_unix(cron:session): session closed for user root Sep 10 17:42:31 user sudo: pam_unix(sudo:auth): auth could not identify password for [user]