wifi scan mode

scan
The process by means of which a wireless network client finds a wireless network:

• Passive scan: walk around with a laptop looking for signals (done aggressively, this is called warchalking, wardriving, etc.) The laptop software listens for beacon frames from other wireless devices.

• Active scan: seeking a specific SSID (wireless network identifier), a laptop or other wireless device broadcasts an association request frame (also called a probe).