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When I perform a Bluetooth LE Scan on my Raspberry Pi 4B (Debian Bullseye) with hcitool why does it include (unknown) entries with the same MAC address as an already listed named item?

pi@raspberrypi:~ $ sudo hcitool lescan
LE Scan ...
12:5E:EE:76:58:72 (unknown)
30:1B:97:75:D2:9B (unknown)
30:1B:97:75:D3:42 (unknown)
30:1B:97:75:D3:42 BLE Device 3891BA
C6:F6:7F:1F:6A:5A LE_WH-1000XM4
C6:F6:7F:1F:6A:5A (unknown)
30:1B:97:75:D2:9B BLE Device 6523F1

For example 30:1B:97:75:D3:42 appears twice as (unknown) and BLE Device 3891BA.

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    The first thing to mention is that hcitool was deprecated by the BlueZ project in 2017. The correct tool now to do the scanning is bluetoothctl. Bluetooth scans can either be passive or active. With active scans there is an additional scan response packet from the device. The BLE device name can be given by the content of the initial Advertising data packet and/or the content of the Scan Response. I suspect what you are seeing is the name is only in the scan response packet.
    – ukBaz
    Jan 1 at 6:47
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    @ukBaz Sounds like a decent answer if you have time -- although you may not know "for sure" if that is why, the reasoning seems pretty solid.
    – goldilocks ♦
    Jan 1 at 20:26
  • Maybe the original poster can have sudo btmon running in a separate terminal to get more detailed information on what packets are being received. It is a very verbose output but hopefully searching for the BT address will easily find the packets of interest. sudo btmon -w btsnoop.log will write a file of a format that be read in to wireshark network analysis tool if you are more familiar with that
    – ukBaz
    Jan 2 at 9:09

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