The process of establishing an ad hoc network involves two steps:
In this section, I'll show you how to set up an ad hoc network between two laptops with Intel Centrino mobile technology running Windows XP. We'll start by defining the ad hoc network on your computer, then we'll go to your friend's computer and join it. Neither stepsetting up the ad hoc network and connecting to itis difficult. In particular, connecting to an ad hoc network is pretty much the same as connecting to any other wireless network.
Starting at your computer, open the Network Connections window either by right-clicking on the wireless connection icon in the taskbar and selecting Open Network Connections, or by selecting the Network Connections item from the Windows Control Panel. With the Network Connections window, select Wireless Network Connection, right-click, and choose Properties from the context menu. The Wireless Network Connection Properties window will open. Click the Wireless Networks tab and you should see a dialog similar to Figure 14.2. (See Chapter 3, "Configuring Your Mobile Computer," for more information about the various Network Connection windows and how to use them.)
Figure 14.2. The Wireless Network Connections Properties window is the starting place for creating an ad hoc network.
Click the Advanced button at the bottom of the Preferred Networks section. This will display the Advanced dialog and give you three choices of networks to access. Click the third radio button, Computer-to-Computer (Ad Hoc) Networks Only. Also make sure the Automatically Connect to Non-Preferred Networks check box is unchecked. The dialog should now look exactly like Figure 14.3. Click the Close button. Doing this step now makes the definition of your ad hoc network a little easier and helps prepare your computer to automatically enable ad hoc networking mode.
Figure 14.3. Set the Advanced dialog to access only ad hoc networks.
Now you should be back to the Wireless Networks tab of the Wireless Network Connection properties dialog. Click the Add button. The Wireless Network Properties window, shown in Figure 14.4, will open. This is where you define the ad hoc network.
Figure 14.4. The Wireless Networks Properties window is used to define a wireless network for ad hoc broadcast.
In this example I have elected not to use encryption to get the ad hoc connection up and running as quickly and easily as possible. If your ad hoc network is going to be running for only a few minutes you might choose to leave encryption off. On the other hand, if you expect your network to be up for any length of time, and especially if there are other people around, you should definitely enable encryption after you have your initial connection established and confirmed your ad hoc network is operational. With encryption off, there is nothing to prevent someone else from detecting and joining your ad hoc network. The files you exchange with a friend or colleague are just as visable to an outsider. Ad hoc networks are easy to set up and join, so make sure this benefit is not turned against you.
In the Wireless Network properties window, enter a name for the ad hoc network (the wireless network's SSID). (In Figure 14.4, I've given the ad hoc network the name theHoc.) Note that the check box This Is a Computer-to-Computer (Ad Hoc) Network; Wireless Access Points Are Not Used at the bottom of the window is already selected and greyed out.
Select the Data Encryption option from the drop-down list if you want to provide WEP encryption protection for the ad hoc network.
Click OK to save the ad hoc network profile you just made. The Wireless Network Connection Properties dialog should look like Figure 14.5.
Figure 14.5. The new ad hoc network appears in the Wireless Network Connection properties window.
Finally, click OK on the Wireless Network Connection Properties dialog to make your ad hoc profile active.
Your computer is now sending out an 802.11 signal called a beacon to announce an ad hoc network is available and open for business. There is nothing to tell you this is happening on your computerthere is no status message or icon to look at. You just have to go on faith that your computer is ready and waiting for another computer to connect to it.