The Pi Sniffer Is an Inexpensive Wi-Fi Sniffer Designed to Fit in Your Pocket

A Wi-Fi sniffer is a specific type of packet analyzer designed to intercept and process wireless packets, useful in a variety of applications in which obtaining data from networks is necessary. This project is definitely skirting the edge of Black and Grey Hat purpose, but still cool though. Beyond access points, you are also able to capture client data using a sniffer, which provides more insight into the networks. A project called the Pi Sniffer — a Wi-Fi sniffer based on the Raspberry Pi Zero W — is a pocket-sized, portable, and inexpensive device from Tenable for viewing real-time status and decrypting packets on the fly.

Current solutions to on-the-go portable wireless sniffers tend to compromise with either bulkier setups or less robust user controls. Still, the Pi Sniffer is meant to offer both portability and control. Using the RPi Zero W as a base offers quite a few pros. It has official support for a Debian-based OS, a built-in antenna, and supports a variety of peripherals. Despite its limited system resources, it turns out to be a decent base for this project’s intentions. The software platform was built on Raspbian Lite with the Re4s0n Kernel.

The design in its entirely runs less than $100 and is only four base components: the Raspberry Pi Zero WH (Zero W with headers), Adafruit 128x64 OLED Bonnet as a display, a power source, and an SD card 8GB or larger. While the sniffer does require the GPIO header on the Pi, this can be bought pre-soldered, so the project does not require any DIY soldering.

The small size isn’t the only unique element of the project. Pi Sniffer also offers controls by which the user can start and stop sniffing, change channels, deauthenticate clients, and more. Software can be installed via flashing the release image, which can be obtained from Tenable's GitHub page. Limitations of the compact, inexpensive design include that the kind of small, cheap GPS that works best for the project may not always be able to maintain GPS signal indoors, so location data may not always be possible although it may be possible to piece together with context clues in the data during post-analysis.

The Tenable team has also been documenting the project’s travels to a few populated locations in the US to see what it can see. Its inconspicuous nature allows it to venture into places where more conventional Wi-Fi sniffing might not be possible. In this case, the sniffer worked its way through a few airports, all documented in a Medium post by creator Jacob Baines.