Detecting beacon via hcitool

In order to scan BLE beacons, you need to first make sure the bluetooth is on. To turn on bluetooth service, you can do

​ sudo rfkill unblock bluetooth

Vice versa, you can turn off bluetooth by typing

​ sudo rfkill block bluetooth

Once the service is on, you can start to scan the beacon by running

​ sudo hcitool lescan --duplicate

Noted that the command only ask the system to start collecting beacons BUT it DOESN’T parse the beacons. Instead, it simply dumps the received messages to a message queue in OS and we need to call another program to retrieve those message, which is

​ sudo btmon -T

Sending beacon via hcitool

We need to set up raw bytes for a beacon when using hcitool to transmit/advertise a BLE beacon. Here is an example from a tutorial

​ sudo hcitool -i hci0 cmd 0x08 0x0008 1E 02 01 1A 1A FF 4C 00 02 15 92 77 83 0A B2 EB 49 0F A1 DD 7F E3 8C 49 2E DE 00 00 00 00 C5 00

For more details, please check this tutorial: here

AWK practice

Task:

  • Print out RSSI only from a certain device using awk.
  • Advanced: only use one awk, not several awk thru pipelines.
  • Advacned II: Print out json formatted address and RSSI using awk.

In case you are using VM that cannot capture BLE beacon, here is a sample file you can practice awk.