Sorry to say...

[shad-99]

Re "advanced" banning:
Simply put, there is no way. This is a big problem in pretty much everywhere the internet is involved, and there is no reliable solution. IP banning is still the best way, but with IPv6, that's mostly done for as well.
Mac address is not an option - it's unique, but the server never receives the client's Mac address, only that of the last switch/router/... in the chain, i.e. it's useless.
Unique IDs wouldn't be a reliable option even if the game was closed-source. Everything that happens on the client, and everything sent over the client's network interface, can be modified.
Actually, the most reliable solution is to ban suspicious clients based on their behavior, i.e. server-side anti-cheat. In that system, the client's IP address - or the player's identity - doesn't matter.

Ok ok ok.. i see! :(.. -i will shut it :P -I was just currious about the whole thing! )