Computer-to-Computer Network

The following diagram shows a wireless configuration known as a computer-to-computer network, a type of ad hoc network that can be configured easily without the need for any additional hardware such as a base station. It provides an easy means to network two or more wireless client computers together.

A computer-to-computer network has the following characteristics:

• Each client can transfer files to and from other clients in the network.

• It doesn't require an AirPort base station; each client has the necessary AirPort card and AirPort software.

• Clients must be in range of each other to communicate.

• AirPort does not prescribe a limit on the number of clients that can join this type of wireless network. (Other factors such as file sharing and software limitations can restrict the number of clients.)

You can create a temporary wireless computer-to-computer network between two or more AirPort-equipped computers without the need of a base station. You can share files and play multiplayer network games over the airwaves. However, you won't be able to surf the Web in this configuration, because your temporary computer-to-computer network is isolated from any other wired or wireless network.

Choose Create Network from the AirPort menu extra or from the Network pop-up menu in the Internet Connect application. Enter a name for your new network, choose a channel (leave on the default unless you know there's another base station in range using the same channel), and then click OK, or click Show Options if you want to enable encryption. We'll discuss wireless security in greater detail later in this lesson; just follow along for now.

From the WEP key pop-up menu, choose 40-bit for maximum compatibility or 128-bit for maximum security. If you choose 128-bit encryption, only computers with 128-bit encryption–capable wireless networking cards can join your network. If you choose 40-bit encryption, all wireless computers can join, but the network operates with a less robust level of encryption.

After you have chosen the type of WEP key you want to use, enter the desired password and confirm your password by entering it again. The password must conform to the composition and length of the type of WEP key chosen. Only after you've entered a valid password in both text fields can you click the OK button.

Current AirPort software and Mac OS X also support the use of WPA for computer-to-computer mode. Setup is essentially the same as for WEP.

Before other users can join your ad hoc network, you must tell them the name of your network and its password. Users entering an incorrect password are excluded from your network without an explanation as to why.

There is an issue with setting up a 128-bit encrypted computer-to-computer network that can cause some confusion. When you set up a 128-bit encrypted network and do not enter a full 13-character password—for example, you enter an eight-character password instead—the client software defaults to a 40-bit encrypted network. When a user on another computer tries to join the network and enters the correct 128-bit password, the user can't connect. The workaround is to always enter a complete 13-digit password when creating a 128-bit encrypted network.