Snort with MadWifi driver on a Atheros CM9 miniPCI wireless interface

See snort-wireless http://www.snort-wireless.org/ for more information.

ifconfig ath0 down
wlanconfig ath0 destroy
wlanconfig ath0 create wlandev wifi0 wlanmode monitor
ifconfig ath0 up
snort -devw -i ath0

Be sure you see beacon from your ap, then configure your snort.conf configuration file (configure --enable-wireless) and invoke

snort -c /your/path/to/snort.conf

NB: Snort-2.4.3 may have some problems.