Ubuntu, How do I see a log of logins made?

Solution 1:

check in /var/log/auth.log
There is no /var/log/secure in Ubuntu -- afaik (that was RedHat?).

Also, remember log rotation (so, lookup the auth.log.N.gz files too).

more ref.

1. LinuxLogFiles at Ubuntu Help pages describe auth.log -- has a lot more details
2. 20 Linux Log Files that are Located under /var/log Directory.

Solution 2:

The command "last" will show you login history.

Solution 3:

Check out lastlog :

petrus@host:~$ lastlog 
Utilisateur      Port     Venant de        Dernière
root                                       **Jamais connecté**
daemon                                     **Jamais connecté**
bin                                        **Jamais connecté**
sys                                        **Jamais connecté**
petrus           pts/0    2a01:e34:ee8c:18 dim. juin 17 20:06:14 +0200 2012