Prevent torrents on Ubuntu server

I need an experienced system admin to make necessary system changes to prevent torrents on my Ubuntu server. Server is a VPN server and it uses Radius for authentication. You can use any solution you like. Only requirement is it has to stop torrents completely. After work is done I need what you have done and all commands entered in a text file. This is a simple project which won't take more than 1 hour. My maximum budget for this project is 30 USD so bid reasonably.