Bluetooth is one of the most widely deployed wireless technologies, yet most discussions barely scratch the surface of how it actually works. Underneath the simple “Pair” button is a layered networking stack that includes HCI, L2CAP, SDP, RFCOMM, ATT, GATT, SMP, and several application profiles, all working together to establish secure communication between devices. Like any complex networking protocol, Bluetooth has also had its share of implementation flaws, from early attacks like Bluesnarfing and Bluebugging to more recent vulnerabilities such as BlueBorne, KNOB, BIAS, BLESA, and SweynTooth. Here’s a comprehensive guide to everything about Bluetooth