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Ad Hoc Networking: Wireless Computer-to-Compuer or Peer-to-Peer Networking

Setting up an Ad-Hoc network is in some ways easier than Infrastructure, but only in terms of settings. The setup is much the same, starting first with creating a common SSID. Once one system has been configured in an Ad-Hoc mode, the network should appear in the list of available wireless networks. After you have the systems communicating, then you can modify the settings to implement some basic security.

We will configure a couple of systems to communicate in a peer-to-peer wireless setup. Just to make things interesting, one system will be Windows XP with an integrated wireless adapter and the other Windows ME with a PCMCIA Wireless adapter. The difference in the Operating System versions only shows up in how you access the various network settings, not in the process that you must follow.

While Windows Millennium Edition (ME) was fairly good with plug-and-play hardware detection, Wireless networks were in their developmental stages at the time. For Windows 98, 98 Second Edition, 2000 or ME to use the wireless adapter, the brand-specific drivers will have to be installed first. Even with Windows XP, you will likely have to install the brand-specific device drivers, although the wireless configuration utility is not really required. For our purposes, only the Windows Drivers and whatever Windows networking support will be used.

On the Windows ME system, I installed the latest D-Link DWL-650 drivers from the D-Link web site. (You gotta' love the Internet for old driver support! Who knows where the original Driver CD is?) When the wireless adapter is installed in the system, Windows ME detects new hardware and loads the appropriate drivers. The TCP/IP protocol is automatically bound to the new adapter in network properties, and Windows has already started scanning for wireless networks. With Windows 98, you may have to install the TCP/IP protocol in the Network Properties if you did not have it previously installed for Internet access. There are two ways to configure the Wireless settings, the quickest is to click on the tiny wireless icon in the system tray. The other method is to select the wireless adapter and click on the properties button in the network properties. Both will display a similar window with tabs for Configuration and Encryption.

The Wireless icon window includes a "Link Info" tab and an "About" tab, neither of which have any impact on you Ad-Hoc configuration. When you are configured for Infrastructure, the Link Info will display the link quality and signal strength, but these are blank when in Ad-Hoc mode. The About tab will identify firmware and driver version details if you need to check to see that you have the latest versions.

To configure the Windows ME system for our Ad-Hoc network, click on the wireless icon in the system tray. Select the Configuration tab in the window that is displayed. On the Configuration window, change the Mode from "Infrastructure" to "802.11 Ad-Hoc". For the SSID, change it from "default" to "Random Access" or whatever you want to call your own private wireless network. Remember from our earlier wireless notes that all of the computers connecting to a specific wireless network must have the same SSID. You can have multiple networks operating within an area, but you can only connect one wireless adapter to a single wireless SSID network at a time. For the transmit speed, PS mode, and Channel, we will leave the default settings. Next select the Encryption tab and change the Encryption (WEP) setting to "Disabled". You can turn this on later, but to set up your network initially, always start simple and work up, one step at a time. Click OK when done making your changes, as this system should now be ready to communicate.

One reason for configuring the Windows ME system first was that once a single system begins to broadcast on an Ad-Hoc network, The network name will appear in the Windows XP list of available networks (as long as the list has not been restricted to showing only Access Points and Infrastructure networks.) To connect to the network under Windows XP, locate your wireless network icon in the system tray; right click on the icon and select "View Available Wireless Networks" In the list of available networks, you should se one for the name of the SSID we created on the first system. Since no encryption has been configured it should show as being an "Unsecured computer-to-computer network". Click to select and then click on "Connect" to join the Ad-Hoc network. This process automatically configures your Windows XP system with the same SSID and no WEP encryption.

You should now have both computers on the network, but how to share folders or play games? As with any network, a system must share its resources on the network to make them available to the other users. On a peer-to-peer network, any system is capable of making folders or printers accessible to other network users. To do this on a Windows 98 or ME system you must have Network File Sharing turned on. In the network properties, click on file and printer sharing, and then add a check mark next to "I want to share files..." Click okay to save the changes and allow the system to restart. Once this has been done, select a folder to share; right click on the folder and select "Sharing". Under Windows 98 and ME, you have the choice to enter a password for read only access, and a password for full access. You are not required to enter a password, but this provides security it terms of allowing only those people who know the password to access your files. If you allow full access without a password, anyone who connects to your Ad-Hock network could see and access your files, and would also be able to add, change or delete files in the folder. To access the shared folder from the other computer, you can "Map a drive" or enter the IP and shared folder name an Explorer window. If you use a password to restrict access to the folder, you will have to use the option "Connect using a different user name" in the Windows XP Map Network Drive window. This allows you to enter the password before connecting to the resource. See our previous networking articles for a review of how to determine your IP address using IPCONFIG or WINIPCFG and use this to map a drive.

Turning on encryption: Now that a basic but "Unsecured" network has been created, turn on WEP encryption on each of the systems. Click on the Wireless Networking icon on the Windows ME system to open the configuration window again and select the Encryption Tab. Change the WEP Encryption from Disabled to 128 bit. For the encryption key, you can generate the key using a text string or manually enter it as a hexadecimal number-letter sequence. Since the text string is quicker, let's do that. Note that the hex version of the key is generated as you type your string, and changes with each new character. This is handy, but it is the long hex key that you need for your XP system to keep connecting. One suggestion would be to use a USB drive or similar method for copying the hex key to a text file to carry to your XP system. Another sneaky method is to type your text to generate the key; click on manual key to switch to the resulting hexadecimal code and copy this to a text (Notepad) file; cancel the WEP change (remember that your network is still insecure at this point); save the text file to your shared folder where the other user can get it over the network This process is similar to the one used by the wizard that is part of the Service Pack 2 upgrade to save the settings to a removable flash drive or other media.

On the XP system, open the Wireless Network Connection list and click on "Change advanced settings" to display the Wireless Network Connection Properties. Click on the Wireless Networks tab, you should see the Ad-Hock name in the Preferred network list. Click on the network to select it and click properties. The SSID should be grayed out; if there is a check in the box next to "The key is provided to me automatically", remove it. Change the Data Encryption to WEP and then paste the hexadecimal key into the box for the "Network key" and the box for "Confirm network key." Click OK to save the changes, and OK to close the properties window. Changing properties is going to break the connection you previously had. Open Wireless Networks and refresh the list if necessary. Your entry for the Ad-Hoc SSID network name should now read "Security-enabled computer-to-computer network". If it does not connect automatically, select the network and click on Connect to reestablish the link.

Troubleshooting tip: If you suspect interference between your wireless network and other networks or 2.4GHz devices (like phones), you can try changing the channel setting to obtain a stronger signal. You should have the option to select a particular wireless channel between 1 and 11. The default on the D-Link is about in the middle on channel 6. To reduce interference from other devices, first try selecting the extreme ends of your channel range (1 or 11). Most phones will automatically scan or switch channels to minimize interference; you may have to do it manually. Like the SSID, all computers on your Ad-Hoc network will need to use the same channel. You may need to configure the other computers to use the new channel before they will see your system.

Troubleshooting tip: Still can't get your Ad-Hoc systems to communicate? See if they can communicate with each other first at a very basic level. PING is a program that will try to send a small test packet to another computer and reports back if the remote computer was found and received it.

Troubleshooting tip: Are you using a firewall such as Norton Internet Security, Zone Alarm, McAfee Personal Firewall, Black Ice, or even the built-in firewall of Windows XP? (Don't forget that Service Pack 2 for Windows XP automatically upgrades your firewall and turns it ON by default.) If you have a firewall, it may need to be configured or have exceptions created to allow you to see and communicate with the other system(s) on your Ad-Hoc network. If you have a firewall, try disabling it to see if you can connect. If you can connect with the firewall disabled, you may need to add the remote computer to the "Trusted" list or configure the Firewall for local "Intranet" access. Worst-case, disable your firewall long enough to transfer your files or play your game, then enable it again when done.

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