How do I find a players IP?!!!!!!!!!!!!

[Phoenixstar117]

So there is this idiot on the server who when he gets banned just makes a new account and joins and breaks the rules all over again. I want to ban his IP, but I do not know how to find his IP.



How do I do this?



PLEASE ANSWER QUICKER! THIS GUY IS GRIEFING EVERYTHING AND WHEN HIS USERNAME GETS BANNED HE JUST MAKES A NEW ONE AND JOINS AND CONTINUES!