Modern Warfare 2 is these days pretty hot topic. Everyone is talking about it and everyone is playing it. However, there is some criticism around the game, which things are broken or badly implemented, so I will hop on the bandwagon and join with shameless bashing and criticism. ;)
Call of Duty: Modern Warfare 2 has broken UPnP support.
UPnP a protocol that enables software to talk with the internet traffic routers. For example, if you have (and most likely you do) some sort of the router in your network and you want to host a multiplayer game on the internet, you will need to tell your router that it should forward all the internet traffic for that game to your server. You will need to punch a hole in your firewall. The problem is that not many people know how to do that. UPnP is an attempt to remove this sort of complicated task. With UPnP your game server1 can tell your router which ports has to forward and where.
As you can see UPnP is enabled and Xfire client successfully enabled port forwarding for itself. Great! However this is not good enough for COD: MW2. The game itself will still report that type of your NAT is Strict. But, but, but? I have no idea why. Windows 7 firewall is also disabled so that is not the problem.
You will have to fix things the old-fashioned way – hand job. COD: MW2 requires ports from 28960 to 29000 to be forwarded to your server. Again, see the picture below.
Run the game, go to multiplayer and check your NAT settings in the lobby. NAT type should say open.
Lube up and Good hunting.
- or the game itself [↩]