Over the holiday weekend I took my old Sony VAIO notebook and loaded Ubuntu Linux on it. As a desktop / end-user distro I’m very impressed with Ubuntu – it is easy to use and configure. Unfortunately, I had some trouble getting my wireless card to work with WPA2 authentication to my wireless network at home. From looking at the Ubuntu forums it seems like this is a common problem. There are some helpful guides; however, none I found covered how to use WPA2 Pre-Shared Key authentication specifically. Fortunately by reading the man pages and some trial and error I was able to get it working.

Here are the steps:

• download the appropriate driver for your card -> Linksys WPC54G v3
• from the download extract the driver file (bcmwl5.sys) and inf file (LSBCMNDS.inf)
• fire up the Synaptic Package Manager and install wpasupplicant & ndis-wrapper
• open a shell and change directory to the location the driver and inf file were extracted to
• install the driver: sudo ndis-wrapper -i ./LSBCMNDS.inf
• check that the driver was installed correctly: ndiswrapper -l if it was installed correctly it should output “driver present, hardware present”
• write the module configuration file: sudo ndiswrapper -m
• load the module: sudo modprobe ndiswrapper
• add ndiswrapper to /etc/modules so the kernel module is loaded at boot time

Now on to the fun of configuring wpa_supplicant to handle the WPA2 authentication for the interface.

• open the /etc/wpa_supplicant.conf file in an editor
• edit the network stanza as shown below substituting myssid and mypsk with the appropriate values for your network

network={
ssid=”myssid”
proto=WPA2
key_mgmt=WPA-PSK
psk=”mypsk”
}

• open /etc/default/wpasupplicant in an editor
• change ENABLED to 1
• change the OPTIONS argument to have values appropriate for your adapter. For my WPC54G v3 I used the following:

OPTIONS=”-i wlan0 -D ndiswrapper -c /etc/wpa_supplicant.conf”

• open the /etc/network/interfaces file in an editor
• add entries for the wlan0 interface – on my notebook I desire the wireless card (wlan0) to be the primary interface. My configuration follows below:

# The primary network interface
auto wlan0
iface wlan0 inet dhcp
pre-up /etc/init.d/wpasupplicant start
pre-up sleep 5

• and we are done

This leaves you with a wlan0 interface that will start automatically, is configured via DHCP, and prior to bringing the interface up the system will start wpa_supplicant to handle the WPA2 authentication so the card can associate with your WLAN.

I found the following to be helpful resources in getting it working:

• WiFi Howto
• WPA Howto
• Getting WPA2 to work on a Broadcom chipset
• WPA Supplicant website

Hopefully this is helpful to anyone else who is struggling to get it working.