This post contains a write-up of the Bluetooth Low Energy Capture the Flag (BLE CTF) as developed by hackgnar. The CTF teaches various core concepts of Bluetooth LE. A more advanced version is now available too, the BLE_CTF_INFINITY. Prerequisites After building and flashing the CTF to the target device (see the documentation for the required steps), ensure the bluetooth service is running using systemctl start bluetooth. Next verify the target device is discoverable: sudo hcitool lescan should return an entry like this: 30:AE:A4:26:2B:E6 BLECTF.