SoylentNews is people
SoylentNews
Submission Preview
Clever Hacker Fits 537,000 Domains in a Tiny $5 ESP32 Ad-Blocking Dongle
EDITORS: THIS HAS BEEN PRODUCED BY SOFTWARE UNDER DEVELOPMENT - THE CONTENT MAY REQUIRE EXTENSIVE EDITING
Firmware Uses Only Around 50KB Of RAM And Can Answer Blocked Lookups In 10 Milliseconds
The specific ESP32-C3 SuperMini board that ZedAxis used.
The project includes a rudimentary GUI where you can see some statistics and configure custom domains for blocking.
The backup ad-blocker is barely noticeable plugged into the creator's home gateway.
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 [tomshardware.com] 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.
Instead, the ESP32-C3 used by ZedAxis has just 400KB of RAM, and 4MB of flash memory. With these limited specifications, he wasn't able to store a plaintext blocklist [tomshardware.com] of any real size; it's simply too much data. So, he did what any enterprising hacker would do: he started hashing the data to reduce its size. Using 40-bit FNV-1a hashes, because 32-bit would give too many collisions and 64-bit wastes too much space, he can store some 537,000 domains in the flash memory of the device.
Of course, this isn't meant to replace a proper Pi-hole or AdGuard Home installation. The ESP32 project has a rudimentary dashboard, but it doesn't provide detailed per-client statistics, historical query logs, or all the knobs and dials that make those platforms attractive. Instead, it's designed as a tiny insurance policy. It sits quietly on the network, sips only a few dozen milliamps of power, and if the primary DNS server disappears for a reboot or a power outage, clients still get filtered DNS responses instead of falling back to whatever resolver the router happens to have configured.
I have no idea whether projects like this will ever become common. Probably not, because most people who want network-wide ad blocking will still buy a Raspberry Pi, a used mini PC, or run AdGuard Home [tomshardware.com] in a virtual machine. Still, it's refreshing to see somebody look at a $5 microcontroller with 400KB of RAM and decide, "Sure, that'll do."
