This guide is only applicable for server installations of Ubuntu. If you are running a desktop installation of Ubuntu, try ["WifiDocs/Driver/Madwifi"] and the [http://madwifi.org/wiki/ MadWifi wiki] for more information.
Checking For Atheros Chipsets
First, verify that your wireless network adapter requires the madwifi device drivers.
Issue the following command: {{{sudo lspci | grep Atheros }}} If there is any output similar to that below, you should definitely install madwifi. {{{00:0e.0 Ethernet controller: Atheros Communications, Inc. AR5212 802.11abg NIC (rev 01) }}} If there is no output, try looking through [http://madwifi.org/wiki/Compatibility] to see if your network adapter is supported.
Installation
Navigate to [http://madwifi.org/] and download and extract the latest version of the madwifi drivers (currently 0.9.2.1) {{{wget http://umn.dl.sourceforge.net/sourceforge/madwifi/madwifi-0.9.2.1.tar.gz tar -xvzf madwifi-0.9.2.1.tar.gz cd madwifi-0.9.2.1}}}
Download the necessary tools, compile and install the module {{{sudo apt-get install build-essential linux-headers-server make sudo make install}}}
Finally, create the file /etc/modprobe.d/madwifi and add the following to it: {{{options ath_pci autocreate=ap }}}
This will tell madwifi to set your wireless device (ath0) to master mode. Finally, load the module {{{sudo modprobe ath_pci }}}
Sources
[http://madwifi.org/wiki/UserDocs/FirstTimeHowTo MadWifi 'First Time User' HOWTO]
[http://madwifi.org/wiki/UserDocs/Distro/Ubuntu MadWifi Ubuntu Notes]
[http://madwifi.org/wiki/UserDocs/autocreate VAP Autocreation Upon modprobe ath_pci]