There’s a new Linux script called Monitor that scans for the presence of beacons and other Bluetooth devices and reports to a MQTT server.
The mechanism doesn’t just scan for beacons. It combines name requests, anonymous advertisements and beacon advertisements to determine when to issue a name request to determine if a device is present and when to issue a name request to determine if a device is absent.
The author, Andrew J Freyer, provides instructions how to set up on a Raspberry Pi Zero W.