Blocking IP addresses

Being new at this I am having a hard time with someone and don't know what else to do, maybe someone can help me.

I have an idiot coming on my board and posting things that are not acceptable, I have blocked the i.p. address each time and added the wild card as well,  I now have a list of 12 i.p.'s for this person and they are still getting in!

The i.p.'s are running real close to each other, I block the exact address then duplicate it except with a wild card at the end, but for some reason they always come up with a new one.

Do people have the ability to change thier i.p. address each time they sign on? Or is that something that happens with some isp's

It's really kind of ticking me off!  What to do?

How do I do that for the just one user?

(you should of known that was gonna be my next question)

Mart wrote: They might not even be that clever, most dial up customers have dynaimic ips not static ips (dynamic ones change each time you dial) Mart.

Are you sure about that? My ISP gives me a dynamic IP for my cable modem, but the IP doesn't change for months and months sometimes...

In the uk dial up is dynamic and changes everytime you dial and broadband is static and doesnt change.

Mart.