port forwarding

does anybody know why when i play online games from behind my router, i dont need to set up port forwarding, but if i design a game in blitz using directplay or whatever, the computers cannot talk to each other because the ports are not forwarded? is there any way of getting round this (ie a specific port number which lets things through?)

thanks

neil

At least one of the computers (typically but not nessecarily the server) needs to have a publically reachaqble IP address.

If your router supports UPnP.

http://support.microsoft.com/kb/240429

I found that by typing "directplay ports" into Google.

kk thank you!

neil