To create an Ad Hoc wireless network with Internet Connection Sharing
Install a Wireless Network Adapter in each PC and create an “Ad Hoc” Wireless Network. This is a network in which the two PCs talk directly with one another, rather than via a Wireless Access Point. “Internet Connection Sharing” is then enabled on the actual Internet connection in the “host” PC and the “client” PC will have Internet access provided the “host” is running and online.

When you enable “Internet Connection Sharing” on the actual Internet connection (modem connection) in the "host" PC, it automatically configures the Network Adapter used to connect to the Client PC with the IP address 192.168.0.1 and Subnet Mask address 255.255.255.0. If there is more than one available adapter, there will be a drop-down menu to select the correct adapter. To enable “Internet Connection Sharing” in Windows XP, right click the Internet Connection in the Network Connections folder, select Properties and then the Advanced tab. Tick the box "Allow other network users to connect through this computer's Internet connection".



To enable “Internet Connection Sharing” in Windows Vista, right click the Internet Connection in the Network Connections folder, select Properties and then the Sharing tab. Tick the box "Allow other network users to connect through this computer's Internet connection".



If you run the Zone Alarm firewall in your “Host” PC, the Internet Zone Security level must be reduced from High to Medium or “ICS” traffic will be blocked. The "client" PC's WiFi adapter should be set to get its IP address automatically, which it does by DHCP from the "host" PC.

This will additionally allow you to run File and/or Printer Sharing wirelessly across the network.

If you are running software firewalls, these must be configured to allow access to the networked computers, which may involve adding their IP addresses in a "trusted" section.