KARMA on the Fon and Sniffing Wireless Network Traffic with Ubuntu – Step by Step

This is the old post but still working :)
KARMA is an application that transforms the right wireless NIC
into the ultimate Access Point. Unlike a regular AP, which advertises
its SSID to whoever wants to connect to it, the KARMA enabled AP
passively listens to any client wireless requests and then responds to
it with the SSID that it probed for and thus impersonating virtually any
Access