If you have a Raspberry Pi and one of those surge protectors that also protects your network cables from voltage fluctuations, you have most of the tools you need to build a cheap network observation device, as long as you’re not afraid to use a soldering iron. When you’re finished, you’ll have the perfect addition to your pen-testing toolkit.
To make this work, you’ll need a Raspberry Pi, any surge protector with RJ-45 protection (the folks at Gnurds used this one), a low-profile SD card adapter for the Raspberry Pi, a few cables, a soldering iron, and some electrical tape. You can get a full parts list (and walkthrough of the build) at the link below.
When you’re finished and plug everything in, you’ll end up with a surge protector that looks completely inconspicuous, but can capture any traffic to and from the system it’s connected to. You’ll have to come back to pick up the SD card periodically, but you could fix that by adding a Wi-Fi or 3G radio to the sniffer, drive up outside, log in, download your data, and drive away (of course, broadcasting wirelessly will increase your odds of detection and make the build bigger, so there are drawbacks.)
Low-profile microSD card adapter for Raspberry Pi – Make your Pi a little slimmer with this microSD card adapter board. It slides in where the SD card goes but is half the length. Pop in a microSD card for a sleeker machine. The microSD card holder is a push-push type so you can push on the edge that sticks out to remove the card when necessary. (read more)
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.