Dr Toker, I had already thought about that, but it is impossible because on LimeWire you can change the port! This is why I was requested another method, and I found the answer:

Linux ip firewall technology known as "layer 7 packet classification" which goes from the type of traffic rather than the port.
see if you can set bandwidth limitations per client, or something like that. or just close all non essential ports.
Thanks to everyone who replied, I think it's safe to say you're all geniuses!