Just a little shout up for those using pfsense + C&C Red Alart 3, C&C RA3.
If you have issues playing online I can recommend you to do these port forwarding under NAT:
TCP – 2901
TCP – 3783
TCP – 4321
TCP – 28900
TCP – 29900:29901
TCP – 6660:6666
UDP – 6500
UDP – 6515
UDP – 13139
UDP – 27900
This solved my problems, I didn’t want to forward 6667 since it’s the standard IRC port which other users on the network uses. You can also take a lower number like 6661-6666.