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Networking Problems

If you are having trouble with the Networking, this page will help you. For example an inability to join games, inability to host games, Firewall/Router/NAT issues etc. By fixing your networking problem you will also resolve the "key unknown" error.

Network Port Usage
Defcon uses the following Network ports (by default) for multiplayer games:
5008 (UDP) : MetaServer (public server listing)
5009 (UDP)
: MetaServer (public server listing)
5010 (UDP) : Game Server
5011 (UDP) : Game Client
Note: If these ports are unavailable when Defcon starts up, it will simply use any available port.
If you are running a Firewall (eg Windows Firewall) ensure it is set to allow Defcon to communicate on those ports.
If that doesn't work, try disabling any Firewalls you have running.
Using a Router?
If you connect to the Internet through a hardware Router or NAT Firewall, it is possible that your Router is preventing Defcon from connecting to games on the Internet.
To see if this is the case try bypassing your Router and connecting directly to the Internet.
Some Routers perform "Port Scan and DOS Protection" or something similar. This is designed to protect against hackers, but can sometimes interfere with Defcon network traffic. If your Router runs this service try disabling it.
Disable UPnP
On some Routers (eg Belkin), having UPnP enabled can cause Defcon's networking to fail. Try disabling UPnP and see if that fixes the problem.
Using DMZ
Some Routers allow you to set up a single computer on your Local Network as a DMZ Server (De-Militarised-Zone). This means your computer will be directly accessing the Internet. If you set up your Game computer as the DMZ Server this will almost certainly solve any Router related problems with Defcon, but does pose a security risk for your computer as you will not be protected by your Router any longer.
Using Port Forwarding
Setting up Port Forwarding can solve most network problems. This applies only if you connect to the Internet through a hardware Router or NAT Firewall, and involves setting up your Router to automatically forward all Defcon related network data direct to the computer running Defcon. This is the final thing to try when everything else has failed. To do this:

· In Defcon's "Network Options" panel (main menu -> options -> network options) set the option "Port Forwarding" to Enabled, and ensure the port numbers are set to default ie 5010 and 5011. You can use any port numbers you wish, just ensure they are fixed.
· Access your admin panel for your Router. Most Routers have a web interface of some kind, in which you can configure the network settings.
· The naming conventions are different for every router, but look for a setting called something like "Port Forwarding". Sometimes it is called "Services", "Firewall Rules", "Virtual Servers" or "Inbound Services".
· You need to create a new port forwarding rule. You need to forward ports 5010 and 5011 UDP (Incoming) to the local IP of your computer. You can find your local IP by typing "ipconfig" at a command line.
· For example, a typical setting would be:
Ports 5010 and 5011 UDP, Incoming -> Forwarded to IP
· Detailed instructions for specific Routers can be found at