Following up on my previous post about Bridging the Gap: Bringing Modern Kismet to OpenBSD, it is time to explore the hardware that makes much of this wireless exploration possible. If you have a spare USB port and a €50 RTL-SDR dongle, you can turn your OpenBSD box into a powerful radio scanner.

What is SDR?

Software Defined Radio (SDR) shifts the heavy lifting of radio signal processing from dedicated hardware circuits to software. Traditionally, if you wanted to listen to a new frequency or decode a new protocol, you needed a specific physical radio. With SDR, the hardware is simply a “dumb” front-end that digitizes a chunk of the RF spectrum; your CPU handles the demodulation and decoding.