This software might block only IP's to access ports or something like that , but an usefull software for that you guys can use : http://www.peerblock.com/ - peerblock software , also you can block even a country to access your server or any kind of provider if you add them all class ip's used by them ( very usefull for country's who are using cheats ) . I hope will help some ppl .
If the memory leak was fixed would be a really great tool :)