Yeah, what Tomao said. They are probably using proxies to "change" their IP which means ban a wide ip range, which is not suggested unless you don't care about people not being able to join your room, or you deal with it psychologically. There is more than one way to stop a flooder, and trying to stop their flood with a script unsuccessfully usually gets them all high and happy and wanting to do it more. If you can talk to the person, you may be able to figure out what they are trying to accomplish by flooding and maybe figure out a way to satisfy them differently.
