How to establish an ad hoc wireless connection

Ad hoc is a Latin word that means "impromptu, temporary (improvised, impromptu)" in Latin.

The AD-HOC structure is a PEER-TO-PEER network structure which eliminates the wireless AP, so long as the computer installed the wireless network card can realize the wireless interconnection between each other; the principle is that a computer host in the network establishes a point-to-point connection equivalent to a virtual AP, and other computers can directly through this point-to-point connection for network interconnection and sharing.

Because the wireless Ap,ad-hoc Wireless LAN network Setup process is very simple, but the general wireless network card in the indoor environment transmission distance is usually about 40m, when more than this effective transmission distance, can not achieve communication between each other; Therefore, this model is very suitable for some simple and even temporary wireless interconnection requirements. In addition, if you want to share the bandwidth of the connection between all the computers in the scenario, such as having 4 machines sharing broadband at the same time, the available bandwidth for each machine is only 1/3 of the standard bandwidth.

Here's how to establish an ad hoc wireless connection:

We'll start with a stand-alone computer that has been wired Ethernet broadband to the Internet. We will then establish an ad hoc wireless network in 3 steps:

The first step is to install the 802.11B wireless network card on the main computer and configure it to be a wireless connection to the computer (ad hoc). The second step is to install a wireless network card on the second computer. To complete the network and provide connectivity to the Internet, you should activate Internet Connection Sharing (ICS) on the host.

Configuring the Host

After you install a 802.11B adapter (such as a Orinoco or Cisco wireless adapter) on your computer, Windows XP automatically detects the NIC, installs the driver, and displays an icon in the notification area. (Now, I'm building an ad hoc wireless network using the Agere Orinoco Silver network card.) Although built-in support for them is available in Windows XP, you can also upgrade them using the updated drivers and firmware via Microsoft Update. If there are other network adapters in the computer's environment, Windows automatically displays a list of available networks. However, if there is no network available in this range, the wireless connection icon displays a red "X" and will not automatically open a View Wireless Networks window. To open this window, click on the Wireless connection icon. At this point, if an available network appears in the Available networks list, do not immediately select one of the available networks. If your computer is already connected to a preferred access point, remove all preferred access points. To ensure that only the connection to the Ad hoc network you want to configure is established.

Then, click the Advanced tab at the top of the window. Select only "Computer to computer (ad hoc) network" and clear to the "Automatically connect to non-preferred network" checkbox if it is already selected. This setting, as well as removing the wired network, ensures that only the ad hoc network is connected.

Click the Wireless Network tab again. Under Preferred network entry, click "Add", as shown in Figure 1. Specify a network name (SSID) in the Wireless Network Properties dialog box. You can use any name you want, but be sure to configure all your computers with that name. Note that since the type of the network has been designated to be connected only to the ad hoc network, it has been marked as a computer to the computer network and cannot be changed again. Because it is easier to run an ad hoc wireless network before attempting to configure the encryption of WEP data, we do not configure Wireless Equivalence Protocol (WEP) at this time. Whether you use WEP will be determined by your environment. In most cases, to get the best protection and security, you should go back to the wireless network properties and specify WEP settings after your ad hoc network starts to run correctly. After you configure the network name (SSID) in the Wireless Network Properties dialog box, a new ad hoc network and a PC network card icon are displayed, indicating that this is a computer-to-computer network. Be aware of the red "X" tag. When the second computer is within this range, and the new ad hoc network is connected, the display will change to a network of computers that are not marked with "X" and that are working.

Configuring a client computer

After installing a agere Orinoco 802.11b Silver PC network card on a second computer, the Wireless Network tab displays a list of wireless access nodes or ad hoc wireless networks within this range, as shown in Figure 4. The new ad hoc network aloha4321 is listed (and marked with a PC Card icon). Activate the network name, and then click Configure. Because WEP will be configured this time, click "OK". Shared connections have now successfully established an ad hoc wireless network, and we will set up Internet Connection Sharing. On the host, open Network connections. (click "Start", click "Control Panel", click "Switch to Classic View", and then click "Network Connection".) Click "Sharing Connection", under "Network Tasks", click "Change this connection settings". On the Advanced tab, select the Allow other network users to connect through the Internet connection for this computer check box. If you are not using a third-party firewall and have not set up Internet Connection Firewall (ICF), be sure to select the checkbox that activates this attribute. (Read the earlier column about why you are activating ICF: Don't let your defenses slacken.) Finally, you can also choose to enable the let other users control or enable this connection check box. After the ICS configuration is complete, the Network Connections window on the host displays the original wired Ethernet connection and displays its status as shared and enabled. The Network Connections window on the client computer displays the connection on the host as an Internet gateway. Now, the user should be able to obtain a 192.168.0.* private address from a DHCP host, with full Internet connectivity.

Configuring WEP

Now that you have successfully established an Internet connection, the next step is to return to the Network Properties dialog box to configure WEP settings to ensure optimal security for the ad hoc network. On the client computer, open the Wireless Network Properties dialog box and select the Data encryption (WEP enabled) check box. Query the key format and key length in the file provided by your network adapter manufacturer. Use your hardware and drivers to support the encryption of the highest (key length). The Agere Orinoco Silver network card is used here, which supports only 64-bit WEP (and 40-bit). With the latest drivers and firmware, Windows XP will automatically find that the hardware supports only 64-bit encryption and will not allow the key to be set to 128-bit. Make sure you use an ASCII network key consisting of randomly selected characters and letters that cannot be easily guessed. The final step is to use the same key and encryption settings to configure the user computer. Note: To take additional security precautions, you can consider changing the key every week.