Online gaming through intranet


I’m playing warcraft 3 at my friend’s internet cafe, but i can’t host games. I’ve read about opening port 6112 tcp solves the problem, but it’s not that easy i think. Our internet connection is dial-up, all PC has fresh XPsp2 with latest updates, and admin privileges. All xp has disabled firewall except our server, where the latest comodo firewall has been installed. in the server pc we installed 2 network adapters. the first is connected to the modem, the second to the lan. We marked our lan as a safe zone to the net for outgoing connections. The internet connection has been shared for the lan (10.0.0.x network).
We created a rule:

from any
to any
where incoming port: 6112 tcp/udp
where outgoing port: 6112 tcp/udp

… and moved below the default block rule.

After that i still can’t host games in the lan. I think we need something to forward incoming connection to the pc in lan. Are there any ideas? Pls help