I setup Home Assistant with the Raspberry Pi Bluetooth module to detect when my fiance and I were home or away (to turn on/off lights, turn off WeMo switches to the curling iron that my fiance always forgets). After a few weeks of forgetting I had it running, I logged back into the Home Assistant dashboard to notice that it was tracking nearly all of my neighbors Android phones, iPhones, headphones, TVs - when they were home, when they were away. Entirely passively. Most devices had names that could very easily be linked back to the user - i.e. "Joe's iPhone".

Just to reiterate - this was _entirely passive_. I did nothing but enable the Bluetooth presence detection module in Home Assistant on my Raspberry Pi, and over time it built up a detailed log of when nearly all of my neighbors were home or away.

Luckily I was able to quickly turn off tracking of devices that weren't explicitly enabled.

What confuses me, is that I thought iPhones had randomized MAC addresses? In the Home Assistant known_devices.yaml file, you can give aliases to phones based on their MAC address. And my iPhone has never changed it's MAC address, because Home Assistant continues to track it with ease. Not entirely sure how that works.