Hi terrorist,
I recommend you reconsider the method of banning him. I mean if you apply hostmask ban, you are also banning who-knows-how-many people who didn't do a thing. And I'm rather sure you don't want it that way. I had it once, some idiot used ZGH multihack and jitspoe (IIRC) applied the hostmask ban. However, he banned millions of people that way, so he had to take it off and ban offender not via IP. So I'd davise you to do the same. But it's up to you of course.
Regards.