Creating an ad hoc WiFi network

  • Presentation of the ad hoc WiFi network
  • Installing drivers
  • Configuring the ad hoc network
  • Resolving problems
  • IP configuration

Presentation of the ad hoc WiFi network

If you have two or more computers equipped with wireless adapters (WiFi cards), it is possible to easily connect them in a network by setting up a so-called "ad hoc" network, that is, a computer-to-computer network, without using an access point.

If one of the computers on the ad hoc network has an internet connection, it is possible to share it with the other computers on the network, like in the case of a traditional local network.

Installing drivers

Before doing anything else, you need to equip all the machines that will be on the future ad hoc network with a wireless adapter and install drivers. You are strongly advised to visit the website of the wireless adapter's manufacturer, to retrieve the latest versions of the drivers, even if you have recently purchased your hardware. Major updates generally take place when hardware is put on the market. In addition, drivers in their packaging are sometimes several months old.

To install the wireless adapter, you need to refer to the documentation provided or, if you run into a problem, perform a search on your favorite search engine with the brand and reference number of your hardware as keywords and one or more keywords such as "installation", "drivers" and "windows".

If the installation goes smoothly, in Windows XP, a prompt window should appear to ask you to continue with the installation and a warning message may appear stating the following:

The software you are installing for this hardware:  
has not passed Windows logo testing  
to verify its compatibility with Windows XP. (Tell me  
why this test is important.)  

Continuing your installation of this software may impair  
or destabilize the correct operation of your  
system, either immediately or in the future. Microsoft  
strongly recommends that you stop this  
installation now and contact the hardware vendor  
for software that has passed  
Windows logo testing.

Click Continue. A balloon should appear stating that new hardware has been installed and prompting you to execute the automatic configuration. The rest of this article describes how to manually configure the ad hoc network connection.

A new icon appears in the bar, indicating the presence of an active wireless adapter in the computer:

Wireless network icon

By default, Windows XP offers a utility making it possible to configure wireless networks. The Microsoft Windows XP wireless network configuration utility disables manufacturer configuration tools. To disable the Windows XP tool, simply click Start/Settings/Network connections, then right-click the icon corresponding to the wireless network and choose Properties. In the wireless network configuration tab, check or uncheck Use Windows to configure my wireless network.

Dialogue box - Use Windows to configure my wireless network

This manipulation involves enabling or disabling Windows XP's wireless network automatic configuration service. An alternative is to go to the control panel/Administrative tools/Services, and then to start or stop the Automatic wireless configuration service.

In the rest of this article, all manipulations will be made using the Windows XP utility (Service pack 2).

Configuring the ad hoc network

The properties dialogue box for the wireless network connection (wireless network configuration tab) presents the networks detected by the wireless adapter and lets you configure them.

To create an ad hoc network, you need to add a new network, identified by a unique name, the SSID. To do so, click the button Add. A new dialogue box opens:

Creating an ad hoc network

To create the ad hoc network, on each of the future network's computers, you simply need to enter the same SSID and check the box "This is a computer-to-computer network". The other options are used to heighten security. Firstly, leave the network completely open (with the options in the above screenshot), so as not to multiply settings that could prevent the first networking.

At this point, the machines on the ad hoc network should be able to connect to each other.

Resolving problems

If the icon on the taskbar shows a small cross, it means that the computer is not connected to the wireless network; you should check the following points:

  • In the list of available wireless networks (single click the Wireless network connection icon on the taskbar), the ad hoc network's SSID should appear. Double click on its name to connect
  • If it does not appear, open the properties of the wireless network connection (Wireless network configuration), click Advanced and make sure the computer is not configured to Networks with access point only (infrastructure)
  • If it still doesn't work, temporarily disable your personal firewalls (including the Windows XP firewall), to reduce the number of causes that could be creating the failure

IP configuration

The previous steps let you connect the various machines. However, to be able to fully use the network, you need to define an IP addressing for the network's machines and set up a certain number of services (web server, shared files, internet connection sharing, etc.).

For this type of network, it is necessary to use a private IP address. There are address ranges reserved to that effect, in this case to will be sufficient (or to if you already have a local network with the previous addressing).

If one of the computers on the ad hoc network already has an internet access it wants to share with the network's other computers, it is usually named (or, but this is just a convention. The other machines will take addresses from the same address range:, etc.

To configure the machine, simply right-click the icon corresponding to the wireless network connection, then choose "properties":

Network connection properties

Then, in the list of protocols, select "Internet protocol (TCP/IP)" and click "Properties":

Internet protocol properties (TCP/IP)

Enter each machine's IP address, making sure not to enter the same IP address twice, as subnet mask and possibly the IP address of the machine sharing the internet access (default gateway, with the address by convention).

Internet protocol properties (TCP/IP)

In the fields concerning the DNS, enter the IP addresses of the name servers corresponding to the connected machine's service provider. To find them out, you can just enter the following command for example (Start/Run) on the machine that's connected to the internet:

cmd /k ipconfig /all

All that's left is to test the connection between the machines on the ad hoc network.

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