How cheap can you build a hardware-based ad-blocking DNS filter? "Free," if you're willing to salvage some used hardware that's being thrown away. What if you aren't so lucky? In the era of the RAMageddon, even a Raspberry Pi will cost you a couple hundred bucks. But you know, you don't even need something that powerful. In fact, you can use a $5 microcontroller to build a fully functional ad-blocking filter with over 500,000 domains blocked and around 10ms latency.
We know that's possible because Egyptian full-stack developer ZedAxis (@M-Abozaid on GitHub) has already built one. Using an ESP32-C3 "SuperMini" board, he's created a backup DNS for his home network that still provides ad blocking. His primary router is a Pi-hole, which is a Raspberry Pi running specialized software to manage DHCP addressing and DNS resolution with integrated ad-blocking. The SuperMini serves as a backup when the Pi-Hole is rebooting or otherwise unavailable.
