ESP32 C3 Adblock

Abstract

1. Introduction

A Pi-hole-style DNS ad-blocker that runs on a $2 ESP32-C3 — no PSRAM required.

The trick everyone misses: you don't need to keep the blocklist in RAM. Store the domains as sorted 40-bit hashes in flash and binary-search them. 140,000+ domains fit in ~0.7 MB of flash and are matched in ~10 ms, using ~50 KB of RAM.

birthday bound — at 141k domains you get ~0, at 537k about 1 (i.e. one unlucky domain gets over-blocked). Dropping to 32 bits would save 20% of the flash but cost ~7 collisions at 250k; going to 64 bits wastes 3 bytes per domain to solve a problem you don't have.

2. Objective

Pi-hole-class DNS ad-blocker on a $2 ESP32-C3 (no PSRAM): 537k domains as 40-bit FNV-1a hashes in flash, binary-searched. UDP DNS sinkhole + web dashboard. https://youtube.com/shorts/RaxszOUMi8E?feature=share

This project demonstrates how C++, Arduino, ESP32 can be applied to a real-world Internet of Things (IoT) problem.

4. Technology Stack

• Any ESP32-C3 board (tested on a C3 SuperMini), 4 MB flash, no PSRAM needed
• Power it from a stable USB source (a phone charger or your router's USB port).
• A USB-A → USB-C dongle lets it plug straight into the spare USB port on the

5. System Requirements

General requirements for this technology stack — check the README for exact versions.

• Arduino IDE / PlatformIO or a C++ compiler (g++)
• Target board (e.g. Arduino, ESP32) where applicable
• Git (to clone the repository)

6. Installation & Setup

git clone https://github.com/M-Abozaid/esp32-c3-adblock.git
cd esp32-c3-adblock

Full setup instructions are in the project README.

7. Future Enhancements

Suggested extensions you can add to make this your own project.

• Add a mobile dashboard using Blynk or Firebase
• Store readings in a cloud database for history charts
• Add alerts via SMS / Telegram when thresholds are crossed

8. Viva / Review Questions

Common questions examiners ask for projects in this domain.

1. Which microcontroller / board and sensors are used and why?
2. How does the device send data (Wi-Fi, MQTT, HTTP, Bluetooth)?
3. Where is the sensor data stored and visualised?
4. How is power consumption managed?
5. How would you secure the device and its communication?

9. Source Code & License

This project is developed by M-Abozaid and published on GitHub under the MIT License. Please follow the license terms and credit the original author when you use or modify this code.