Apple eNews: Fun and Games with AirPort

But what if not everyone can come to your house to play? Can friends across the street, across town, or across the country join the fun?

Of course—because AirPort also lets you play the host for an Internet game, allowing others to log on to your computer from wherever they happen to be. If they can access the Internet, they can access your computer over the web.

To act the host, you’ll have to take a few preparatory steps. Start by setting up Port Mapping. To protect your files, the AirPort base station acts as a firewall, keeping other people out of your system while you surf the web. Of course, if you want people to be able to access your system, you have to tell AirPort to let them in. To do so, open the AirPort Admin Utility (you’ll find it in the Utilities folder inside the Applications folder in Mac OS X and in the Apple Extras folder in Mac OS 9), select your base station, and click Configure.

Using Mac OS 9? In the Configure box, click the Network tab, then click on the Port Mapping… button. Make sure the radio button next to “Share a single IP address (using DHCP and NAT)” is selected. Select “Add” in the dialog box that appears.

In Mac OS X, select the Network tab in the Configure window and make sure that the radio button next to “Share a single IP address (using DHCP and NAT)” is selected. Then select the Port Mapping tab and click the Add button next to the table of IP addresses.

In both Mac OS 9 and Mac OS X, the dialog box you’ll see next asks you to enter the private and public port numbers you’d like created for your system. Enter the port numbers appropriate for the game you intend to play, and click Done.

Not sure which port numbers to use? Some games, like Rogue Spear, will provide them. Check the documentation for the game you want to play, or start the game and enter the multiplayer setup area. Or you can try the following: Quake 3 (27960); Rogue Spear (2346, 2347, 2348, all of which are needed to host Rogue Spear); Unreal Tournament (7777, 8888, 9999, only one of which is needed); Sin (22450).

After you’ve set up your AirPort base station to allow external access, you have to provide your Internet Protocol (IP) address to your friends. They’ll enter that address in the multiplayer area of the game you’re all playing.

If you don’t know your IP address, check with your Internet service provider (ISP). As part of your account setup, you connect to the service using either a static IP address (which doesn’t change) or a dynamic address (which changes each time you connect).

If your ISP can’t help, you can also use a Shareware program called “My IP” to determine your IP address. (You can find it at the Version Tracker website by searching for "My IP.")

Whether you’re using it as the center of a local area network or to host an Internet gaming party, you’ll want to get the best performance from your AirPort base station. Remember, it’s a transmitter, so you should place it in an open spot as high as possible. (Check the manual for mounting instructions.)

While the signals won’t have much difficulty penetrating wood and glass, metal will reduce the base station’s broadcast range. Appliances that can interfere with radio signals—such as microwave ovens and cordless telephones—may also cause problems if they’re on while you’re using a base station.

If you need further assistance, visit Apple’s Technical Information Library and search for the term “airport.” You’ll find many articles to assist you.

And don’t forget about the Knowledge Base and Apple Support Discussions.

What if a group of you all have AirPort cards in your computers but don’t have immediate access to a base station? Once again, you have two alternatives. One—though this is an option only for Mac OS 9—is to set up a “software base station”; the other, networking via a peer-to-peer relationship.

To create a “software base station” in Mac OS 9, locate and open the Assistants folder on your hard drive. Doubleclick on the “Airport Setup Assistant,” and follow the step-by-step instructions for setting up a software base station, which is very similar to the process described earlier for setting up a hardware base station.

The second alternative—creating a peer-to-peer relationship—is a good choice for you and one to two friends. Set-up is simple. In Mac OS 9, open your AirPort software (via either the Apple menu or the Control Strip), look for the “Choose network” section, and select “Computer to Computer.”

In Mac OS X, open your AirPort software from the AirPort signal strength indicator at the top of your screen (click on “Open Internet Connect”). In the drop-down menu next to “Network,” select “Create Network” and then enter the necessary information to create a peer-to-peer relationship. (Don’t see an AirPort signal strength indicator in the menu bar? Open System Preferences and click the Network icon; select the AirPort tab and click the box next to “Show AirPort status in menu bar.”)

Please note: if you create a peer-to-peer network, keep the number of players to a minimum. As you add players, you begin to encounter a phenomenon called “latency,” a general system slow-down caused by network traffic.

Latency can also occur when you use a Mac to act as a host for a software base station. Because of the network activity it must process, it will not be as responsive as a computer that’s simply accessing the network, so you shouldn’t assign the host computer to a player.