There's no way to harvest the MAC address of a wifi device that hasn't connected to your network, is there?
Yes, there is. If you set your WLAN interface to monitor mode and run tcpdump or similar, you can look at packets passing by, even if you're not connected to a network at all. I built a Wifi tracking system this way when I was in school.
Thanks for that. I wanted to understand how this was working.
This seems like a pretty powerful data source to use for all sorts of things, if it's always accessible like that. A world readable cookie for every yuppie and hipster on the planet!
Yes, there is. If you set your WLAN interface to monitor mode and run tcpdump or similar, you can look at packets passing by, even if you're not connected to a network at all. I built a Wifi tracking system this way when I was in school.