Departments of Transportation around the country have deployed "little white boxes" -- Bluetooth detectors used to monitor traffic speeds and activity. While they're supposedly anonymous, they detect a unique ID from every car and phone that passes by. In this presentation explore the documentation on these surveillance systems and their capabilities, then build a Bluetooth detector and recorder out of less than $200 of open-source hardware and software, as well as turn it on the surveillance system and try to detect and map the detectors as well.