[cod] Call of Duty 4 Server - Public IP access doesn't work ("Awaiting connection")

[Wynne Garland]

Hi, cod at icculus.org.
I'm setting up a Call of Duty - Modern Warfare server on an Ubuntu 10.04 box, using the latest version of this Linux port of the server (I think), cod4-linux-server-06282008.
The problem is simple to grasp: every time someone tries to connect to my box using my public IP, it just says "Awaiting connection", although the exact same setup works using the Windows version.
What I'm doing/already tried:I'm forwarding the 28960 UDP port traffic to my Ubuntu box (through the router configuration system), and I know this is working because I see the traffic of my friends trying to connect getting to the box, with the server providing no answer. If I do it using the server's local network IP, it shows the traffic being replied and my friends do connect, as usual. My router has a firewall and an intrusion detection system (Thomson TG784), both of them were shutdown during every attempt, to make sure no security mechanism is blocking the traffic (and, as I said, I'm sure the box is receiving the external incoming packets, exactly the same way it receives the local ones).
When I set dedicated as 2, it says "dedicated is read only"; I read it somewhere that it already defaults to 2, so it should be correct.I was not setting net_ip value; I read that it defaults to 0.0.0.0, so it should be listening on all interfaces (although local network traffic and external network traffic are coming through the same interface, but just to be sure...). I also tried setting it to the local IP and to the external IP. Nothing worked.

It gives me an error when trying to bind to the external IP; that's because it connects to a router that connects it to the Internet, no interface has that IP binded. I saw many people on the web saying that binding to the external IP is not exactly correct, so every attempt I make I use 0.0.0.0, just to be sure.
Is there any need to set some special rule on iptables? I've been tinkering with some rules, SNAT and DNAT essentially, mangling the packets so they appear to come from the internal network.
I've tried everything, googled a lot about my router and my setup, tried searching similar problems with people using the Linux version of the server... A person or two seem to have my problem, but all problems were solved by correctly forwarding the port.
Today I got a friend of mine to successfully connect to the Windows version of the server using the external IP, dismissing any thoughts that the router could be the problem.I'm sure it must be something I'm forgetting to check.
I'd appreciate your help. If you need any kind of information to help me solve my problem just ask, I'll gladly provide anything I can.
Thank you very much in advance. 		 	   		  
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