Would the usermanager inside of the RouterBoard a solution for you, or if this are
masses of gamers perhaps with syncookies?
Maybe i explained it bad, because i have no idea how to use usermanager to help me.
I have few gaming servers behind mikrotik (provider refused to give me more public IP's). Mikrotik works as router and firewall for 4 machines with 600-800 players.
Problem is, when some player start breaking rules and we ban him by IP/nick. He finds some public proxy server, connnects again with another nick/IP and starts breaking rules again
I need to block access from these proxies to prevent players change IP 50 times a day.