If players are not able to join your game, you may have a firewall in place. Firewalls may prevent incoming networks from reaching your computer and prevent you from hosting games.
A firewall can come in many forms. In households, they may exist as security software, router and/or modem. The following information will help you configure your firewall.
Ports
Ports can be thought of as points of connection. The game listens to these ports to receive all of the information it needs to function. You will need the following ports opened to allow your game to accept connections and to host games:
Diablo and Warcraft II Battle.net Edition:
Allow port 6112-6119 TCP and UDP out and in
Diablo II:
Allow port 6112 TCP out and allow established sessions in
Allow port 4000 TCP out (realm games)
Allow port 4000 TCP out and in (hosting open games only)
StarCraft:
Allow port 6112 TCP and UDP out and in
Warcraft III:
Allow port 6112 TCP out and allow established sessions in
Allow port 6112 TCP in (hosting custom games)
Allow port 6113-6119 TCP out and in (hosting custom games if you have changed the default port in the Options/Gameplay screen)
You may recognize names such as Norton Internet Security, McAfee Personal Firewall Plus/Express, ZoneAlarm, Sygate, Panda, and many others. These security programs act as firewalls that can block single programs or specific ports from the network. Here are some links to popular software firewalls that may help you:
Virtually all routers available today have firewall functions to protect users from outside access. In addition to this, DSL and Cable modems may have firewall functions as well. These links will give you information on how to configure your products. For port numbers and information, please see above.