HostAP Prism Driver for Linux

One of the most exciting things you can do with a Linux machine is to turn it into an AP. The HostAP driver works with Intersil's Prism 2/2.5/3 chipsets. We are used to describing client cards as having the ability to operate in either ad-hoc or infrastructure mode. However, using a Linux box and an off-the-shelf Prism card, the HostAP driver gives you an option to use a third mode called master. In this mode, your wireless NIC becomes an AP. You can download the latest version from http://hostap.epitest.fi/.

If you are running Red Hat, you can actually install a ready-to-go RPM that includes an entire kernel preconfigured with HostAP. You can download the latest RPM from http://www.cat.pdx.edu/~baera/redhat_hostap/. Don't forget to put the hostap_cs.conf file in /etc/pcmcia.

Once HostAP is installed, you can configure it with the familiar Linux wireless extensions tools. (For more information, visit: http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Tools.html)

Use ifconfig to set an IP address for the wireless interface:

• ifconfig wlan0 192.168.1.1

Use iwconfig to set up wireless parameters:

• iwconfig wlan0 essid MyNetwork (this sets the ssid to MyNetwork)

• iwconfig wlan0 channel 6 (this sets the channel to 6, but you can choose any channel from 1 to 11)

• iwconfig wlan0 mode Master (this sets the mode to master)

Note that the mode parameter has three options: Setting the mode to master indicates you want the WLAN NIC to operate as an AP; setting it to managed indicates you want the WLAN NIC to operate as a client in infrastructure mode; setting it to ad-hoc indicates you want the WLAN NIC to operate in ad-hoc mode.

Keep in mind that in its current form, HostAP does not support USB devices. If you absolutely require USB support for your WLAN NICs, you must use WLAN-NG. See http://www.linux-wlan.com/linux-wlan/ for more information about the WLAN-NG driver.