Does anybody know how to make a deticated server for Action Half-Life 2?

You need to make sure you don't make a listen server. Ala a variable that chooses "listen 0" or "dedicated 1" something in those lines. The machine you create the server on needs to have router ports forwarded to it. For example if people connect to :7777 port. You need to forward the ports from your router to the hosting machine/server. Alternatively you can rent a game-server, but those cost..

When people connect they need to know your public IP. The one you get from sites like "whatismyip" etc.

Also you need to use the half-life dedicated server tool and set the corresponding settings. Unless you run it from the game and just untick "listen". Unless that was only in half-life 1. ahaa..