IP address is unreliable.
DB sessions could be a way to go, although last_impression timestamp for logged on users can be used as a cut-down version. You need a clean up with these though (php script or MySQL trigger), unless you run a cron job every 20 minutes or so.
Reputation Points: 1048
Solved Threads: 949
Sarcastic Poster
Offline 6,698 posts
since Oct 2006