Wirelessly networking a second or third computer without a wireless router or a standalone wireless access point (WAP) is considered an ad hoc wireless network. You can build an ad hoc 802.11b wireless network using the graphical user interface in Windows XP. Here's how to add Internet Connection Sharing on the host computer and set up an ad hoc wireless network.
You'll first need to install an 802.11b wireless card in the main computer and configure it as a computer-to-computer (ad hoc) wireless connection.
After you install an 802.11b adapter on a computer, Windows XP will automatically detect the card, install drivers, and display an icon in the notification area.
If the computer is in an environment where other wireless networks are in range, Windows should display a list of available networks automatically. However, if no wireless networks are in range, the wireless connection icon may display a red “X” and may not automatically open a View Wireless Networks window. To open this window, click the icon for the wireless connection.
Do not select an available network at this time if any are displayed in the Available networks listing. If your computer previously connected to a preferred access point, remove all preferred access points. This will ensure that a connection is made only to the ad hoc network that you are trying to configure.
Click the Advanced tab at the top of the window. Select Computer to computer (ad hoc) networks only and clear the Automatically connect to non-preferred networks box if it is selected. This setting, along with removing preferred networks, ensures connection to the ad hoc network only.
Click the Wireless Networks tab again. Under Preferred Networks, click Add. In the Wireless Network Properties dialog box, specify a Network name (SSID). Use any name desired, but be sure to use it to configure all computers. Note that the network type is already marked as a computer-to-computer network and that this cannot be changed since it has already been specified that a connection should be made to only ad hoc networks.
After configuring the network name (SSID) in the Wireless Network Properties dialog box, the new ad hoc network will be displayed with a PC Card icon to designate that this is a computer-to-computer network.
After installing an 802.11b Silver PC Card in a second computer, the Wireless Networks tab displays a list of in-range wireless access points or ad hoc wireless networks.
The new ad hoc network should be listed. Highlight the network name, and then click Configure. Because WEP will not be configured at this time, click OK.
Follow these steps to share the connection:
Click Start, click Control Panel, click Switch to classic view, and then click Network Connections.
Click the connection to be shared, and then, under Network Tasks, click Change settings of this connection.
Click the Advanced tab, and then select the Allow other network users to connect through this computer's Internet connection check box.
If you are not using a third-party firewall and have not already set up the Internet Connection Firewall, select the Internet Connection Firewall (ICF) check box to enable this feature.
Enable the setting to let other users control or enable this connection.
After completing ICF configuration, the Network Connection window on the host computer will display the original wired Ethernet connection and display the status as Shared as well as Enabled. The Network Connection window on the client computer will display the connection on the host as an Internet Gateway.
The client computer(s) should now receive a private class, non-routable IP address in the 192.168.0.* address range via DHCP from the host computer and should have full Internet connectivity.
If connectivity has now been established successfully, return to Network Properties and configure WEP settings to ensure security for the ad hoc network.
On the host computer, open the Wireless Network Properties dialog box and select the Data encryption (WEP enabled) check box. Consult the documentation provided by your wireless card manufacturer for the key format and key length.
Use the highest level of encryption possible (key length) that is supported by your hardware and drivers. Be sure that if you use an ASCII network key that you pick random characters and letters that can't be easily guessed. The final step is to use the same key and encryption settings and configure the client computer(s).
For additional security, consider changing the key on a regular weekly basis.