KisMAC is an open-source and free WiFi stumbler/scanner application for Mac OS X. It has an advantage over MacStumbler/iStumbler/NetStumbler in that it uses monitor mode and passive scanning.
KisMAC supports several third party USB cards - USB Prism2, and USB Ralink support. All of the internal AirPort Extreme hardware is supported as well.
Please note: This program is not intended for novices but for professional users. Take this as your warning, you should be prepared for advanced topics and know what you are doing with your system.
* Reveals hidden/cloaked/closed SSIDs
* Shows logged in Clients (with MAC Addresses, IP addresses and signal strengths)
* Mapping and GPS support
* Can draw area maps of network coverage
* PCAP import and export
* Support for 802.11b/g
* Different attacks against encrypted networks
* Deauthentication attacks
* Kismet drone support (capture from a Kismet drone)
Supported hardware chipsets:
* Apple AirPort Extreme
* Ralink rt2570 and rt73 USB devices
* Bruteforce attacks against LEAP, WPA and WEP
* Weak scheduling attack against WEP
* Newsham 21-bit attack against WEP
Operating System Support: Mac OS X 10.6or later.