====== User login information ======

===== Last =====

show listing of last logged in users

  last
  username   pts/0        192.168.1.1    Fri Apr 27 13:30 - 13:30  (00:00)    
  username   pts/0        192.168.1.1    Fri Apr 27 13:29 - 13:29  (00:00)    
  username   pts/0        192.168.1.1    Fri Apr 27 13:28 - 13:28  (00:00)    
  reboot   system boot  2.6.32-220.13.1. Fri Apr 27 13:27 - 13:31 (3+00:03)   
  username   pts/0        192.168.1.1    Fri Apr 27 13:02 - down   (00:21)    
  root     tty1                          Fri Apr 27 11:07 - 11:07  (00:00)    
  root     tty1                          Fri Apr 27 10:59 - 10:59  (00:00)    
  username   pts/0        192.168.1.1    Fri Apr 27 09:06 - 12:57  (03:50)
  
===== utmpdump =====

utmpdump will write out more information including year

  utmpdump /var/log/wtmp
  [1] [00000] [~~  ] [shutdown] [~           ] [2.6.32-220.7.1.el6.x86_64] [0.0.0.0        ] [Tue Apr 17 10:57:01 2012    ]
  [2] [00000] [~~  ] [reboot  ] [~           ] [2.6.32-220.7.1.el6.x86_64] [0.0.0.0        ] [Tue Apr 17 10:57:19 2012    ]
  [1] [00051] [~~  ] [runlevel] [~           ] [2.6.32-220.7.1.el6.x86_64] [0.0.0.0        ] [Tue Apr 17 10:57:19 2012    ]
  [7] [30220] [ts/0] [user    ] [pts/0       ] [192.168.1.1       ]        [192.168.1.1    ] [Tue Apr 17 15:08:27 2012    ]
  [8] [30220] [    ] [        ] [pts/0       ] [                    ]      [0.0.0.0        ] [Tue Apr 17 15:08:33 2012    ]
  [7] [30748] [ts/0] [user    ] [pts/0       ] [192.168.1.1       ]        [192.168.1.1    ] [Tue Apr 17 15:08:38 2012    ]
  [8] [30748] [    ] [        ] [pts/0       ] [                    ]      [0.0.0.0        ] [Tue Apr 17 15:08:42 2012    ]
  [7] [00748] [ts/0] [user    ] [pts/0       ] [192.168.1.1       ]        [192.168.1.1  ]   [Tue Apr 17 15:11:02 2012    ]
  
===== Failed login =====

utmpdump can also bed used to list failed login attempts

  utmpdump /var/log/btmp
  [6] [27213] [    ] [admusr ] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Mon Apr 16 12:23:27 2012    ]
  [6] [27213] [    ] [admusr ] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Mon Apr 16 12:23:28 2012    ]
  [6] [27213] [    ] [admusr ] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Mon Apr 16 12:23:28 2012    ]
  [6] [29156] [    ] [admin   ] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Mon Apr 16 12:23:46 2012    ]
  [6] [24937] [    ] [devadm] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Tue Apr 17 07:44:42 2012    ]
  [6] [24937] [    ] [devadm] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Tue Apr 17 07:44:44 2012    ]
  [6] [25408] [    ] [devadm] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Tue Apr 17 07:44:56 2012    ]
  [6] [25408] [    ] [devadm] [ssh:notty   ] [192.168.1.1         ] [192.168.1.1    ] [Tue Apr 17 07:44:57 2012    ]