Cisco ASA 8.4 enable logging, Syslog Server

If you wish to log to the console, you can use the logging console command.

This table shows you the levels of logging available:

 <0-7>          Enter syslog level (0 - 7)
  WORD           Specify the name of logging list
  alerts         Immediate action needed           (severity=1)
  critical       Critical conditions               (severity=2)
  debugging      Debugging messages                (severity=7)
  emergencies    System is unusable                (severity=0)
  errors         Error conditions                  (severity=3)
  informational  Informational messages            (severity=6)
  notifications  Normal but significant conditions (severity=5)
  warnings       Warning conditions                (severity=4)

If you wish to use a syslog server, the very excellent visual syslog is free and open source, and works well.  http://maxbelkov.github.io/visualsyslog/

It uses the default port 514

From the config prompt, use the logging host command.

Use logging trap to set the level.  If you use level 7, you will find ASA is too verbose.