ESP32-C3 Adblock
A new open-source project enables a low-cost ESP32-C3 microcontroller to function as a Pi-hole-style DNS ad-blocker without requiring external PSRAM. The solution utilizes a technique that stores domain blocklists as 40-bit hashes in flash memory, allowing for efficient binary search lookups with minimal RAM usage. This approach significantly reduces hardware costs and power requirements compared to traditional methods that rely on storing full domain strings in volatile memory.
- ▪The project stores over 140,000 domains as 40-bit hashes in approximately 0.7 MB of flash memory, using only about 50 KB of RAM for operations.
- ▪By using hash-based binary search instead of string comparison in RAM, the device achieves a lookup time of roughly 10 milliseconds while avoiding the need for expensive PSRAM modules.
- ▪The hardware setup requires only a standard ESP32-C3 board with 4 MB of flash, which can be powered directly from a router's USB port without a separate power supply.
- ▪Collision rates for the 40-bit hash scheme are negligible at 141,000 domains, with the birthday bound predicting only one collision at 537,000 entries.
- ▪The firmware supports over-the-air updates and includes a web dashboard for managing blocklists, with security credentials required for state-changing endpoints.
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| Original publisher | GitHub |
| Canonical URL | https://github.com/M-Abozaid/esp32-c3-adblock |
| Publication time | Wed, 07 Oct 2026 01:39:21 +0000 |
| Retrieval time | 2026-10-07T03:36:36.028Z |
| Last seen | 2026-10-07T03:36:36.028Z |
| Headline source | Publisher (no WeSearch rewrite) |
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| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
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| Publisher visit | Yes — open original |
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| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
esp32-c3-adblock 日本語 README A Pi-hole-style DNS ad-blocker that runs on a $2 ESP32-C3 — no PSRAM required. 📰 Featured on Tom's Hardware, XDA Developers, and Korben. 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. query in ──▶ extract domain ──▶ FNV-1a hash (+ parent suffixes) ──▶ binary-search the flash hash table ├─ hit ──▶ answer 0.0.0.0 (sinkholed) └─ miss ──▶ forward to upstream resolver, relay the reply Why this is interesting Most ESP32 DNS sinkholes load the blocklist (domain strings) into RAM, so they demand PSRAM.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at GitHub.