Question regarding IP address?

I was wondering is it only possible to view a member of your forum's IP when they're online? Reason being is I have a pesky member who keeps coming back despite the fact he's banned, I've banned his email address but he keeps creating new accounts so I need to IP ban him. I always seem to miss when he's online though so I can't grab his IP to do this
I've looked through most of the pages on the administration panel but I can't seem to find anything anywhere.

You can go to one of this old post and click on the IP button to get his IP. Then you can ban him.

Ah wonderful, thanks!