How do you host a Halo CE server with your foreign IP address not your local 192 one

Most routers (even home routers) have a feature known as port forwarding; you set the ports for Halo to forward to your 192 based server. The net result is that external users are routed to your server by using an external IP address and don't know that this is happening.

For example, if a game or an application uses port 5000 to communicate with the server, set port 5000 to the 192.168 address of your server. If your external IP address for the router is (for example) 31.44.55.66, then users can get to your server by using the 31 address, but packets for the game will be routed to your 192.168 server which is internal.