If you have a laptop which has a Atheros 9285 wireless card you will need the following to make it work with Ubuntu Lucid:
lspci -v | less
This will tell you what the the wireless chipset is.
Download
You can download the driver at http://linuxwireless.org/en/users/Download/stable/. These are stable releases, so choose the most recent version unless you have a compelling reason not to do so.
Step 2: Unpack
Run these commands in a terminal window (Applications->Accessories->Terminal):
This assumes you have downloaded the 2.6.30 driver onto the Desktop. Change the commands below for your circumstances.
cd Desktop
tar -xf compat-wireless-2.6.30.tar.bz2
cd compat-wireless-2.6.30
make
sudo make install
sudo make unload
Inside drivers/net/wireless/ath/ath9k you will find the following files:
ath9k.ko ath9k_common.ko ath9k_hw.ko
Type sudo modprobe ath9k
This will pick up the ath9k network driver, you should see a wireless network icon appear in the top right of the toolbar.
So this new drive is present the next time you reboot type:
sudo update-grub2
Then do a su -
vi /etc/modules
Type ath9k on new line. Save the file, and reboot.
Avoid ndiswrapper as this will reduce the performance of the network card.
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Update - if you are issues with Ubuntu 10:10, with wireless dropping, and dns issues - install the wireless backport - for maverick:
sudo apt-get install linux-backports-modules-wireless-maverick-generic