System don't keep firewall preferences to other users

Hi. My sun uses two problematics apps: Minecraft and Skype. I change Firewall preferences to allow connections but when he tries to play, is blocked. System ask for my username and password to allow connection when he tries to connect to game-server. I do put my username and password, click "allow" but it doesn't. If I look at preferences inside his user session, it still blocked, so system is ignoring my order. The same happens to Skype.

I gess I'll have to do it using the Terminal, but I got no idea of how to do it...