1. It talks to the BitTorrent "tracker" on Port 6969.
2. It talks to other BitTorrent downloaders using Ports between 6881 and 6889.
So, the solution comes this way:
Go to your server or your router configuration menu(you must get the access right to it!!), DISALLOW all communications of BT by BLOCKING port 6969, port 6881 to port 6889.
