Kismet is a sniffer, WIDS, and wardriving tool for Wi-Fi, Bluetooth, Zigbee, RF, and more, which runs on Linux and macOS.
AirSnort is a wireless LAN (WLAN) tool which cracks encryption keys on 802.11b WEP networks. AirSnort operates by passively monitoring transmissions, computing the encryption key when enough packets have been gathered.