I'm not sure I follow. Why would a network known to the device not be connected to the network? If you never connected your device to their wifi and only connected to your wifi connected via ethernet, why would it even know to make a request? If you're not actively connecting to the WiFi in your house, why not just "forget network"? Seems like a strange hypothetical, but aren't they all?
> Why would a network known to the device not be connected to the network?
I think they're referring to when you leave your home. Your device(s) will be constantly broadcasting probe requests for the hidden network.
The away-from-home probe requests wouldn't be that useful for mapping, but your AP/router is equally useful for mapping with or without broadcasting the SSID. Hiding your SSID just means it sets the SSID to null in the beacon frames but it's still sending out beacon frames with its far-more-unique MAC address (BSSID). If you're on linux you can see this pretty easily by running `sudo iw dev wlan0 scan`. The "hidden" wifi networks will have their SSID as "SSID: \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" but all the other information including MAC address is still there. Personally it seems there are two "hidden" wifi networks within range of my bedroom.
