This $50 Gadget Does the Job of a $500 Network Tester

When you’ve got a home network with one or two switches, it’s pretty easy to keep track of information like their IP addresses and hostnames. However, things get way more complicated when you’re working in a data center. With each row of racks looking identical to the one that came before it, there is no way to keep everything straight by memory. Relying on stickers isn’t a great plan either — things may change, or installers may forget to use them.

If you want to be certain that you’ve got the right information, you need to have a pocket network testing tool. But since these tools cost hundreds to thousands of dollars — and sometimes even require a smartphone for use — GitHub user MKWB decided to build a DIY network tester to save some cash. It’s made from inexpensive hardware and it’s easy to use: simply plug it into an Ethernet port and it displays the switch hostname, IP address, port number, and VLAN info on its onboard display.

Called the RaspberryFluke, the device is built around a Raspberry Pi Zero 2 W single-board computer. Inspired by professional-grade port identification tools, it offers a stripped-down but highly practical alternative for technicians who need quick answers in the field without carrying bulky or expensive equipment.

The device leverages LLDP (Link Layer Discovery Protocol) and CDP (Cisco Discovery Protocol), two widely used networking standards that switches use to broadcast their identity and configuration details. By listening for these packets, RaspberryFluke can automatically extract critical information. This data is then presented on a low-power 2.13-inch E Ink display, making it easy to read even in bright environments while conserving energy.

Alongside the Raspberry Pi, the device uses a Waveshare E-Paper HAT for display output and a PoE Ethernet/USB hub enclosure for connectivity and power. When plugged into a PoE-enabled switch port, the device powers up instantly without needing batteries. Alternatively, it can run from a USB power bank, adding flexibility for different environments.

On the software side, RaspberryFluke runs Raspberry Pi OS with a lightweight Python script that handles packet parsing and display updates. A systemd service ensures the tool launches automatically on boot, allowing it to function as a true plug-and-play solution. Once connected, it quickly gathers and displays relevant switch data without any user interaction.

While it may not replace high-end commercial testers entirely, RaspberryFluke demonstrates how accessible hardware and open-source software can replicate essential features at a fraction of the cost. This makes it an appealing option for hobbyists, IT professionals, and anyone managing complex network infrastructure.