Welcome Thorman

, if you and your son are on the same IP, I believe he can start a LAN game instead of an internet game, which makes it so only you and your son can play. Just install it on both computers, make sure you have the correct version (the 436 patch for each), one of you start a multiplayer game via multiplayer tab, and go to the server tab in the new opened box, scroll down a bit and you should see Optimize for LAN, check that so he can connect, then set everything else to how you want it, (You can leave MOTD lines blank, those are just for messages when you enter a server, same thing with WWW Remote Admin, WWW Password, and WWW Username). You can also add mutators, which add stuff to the game, UT has a ton of downloadable mutators from
www.moddb.com. Mutators have new weapons, game types, ect and are player made. Ok so after your done, start the server and go to your other comp, go to Open Location in the multiplayer tab, and type in your IP, and you should be able to connect

. Or you could click on it in the LAN games tab in the Find LAN games browser. I just make maps and play UT though, so I don't know too much about servers lol

.