ZDNET Author Builds $7 ESP32-S3 DNS Sinkhole as Raspberry Pi Alternative

Q: Is routing your home's internet through a $10 DIY device a brilliant privacy hack or a major security risk?

It is mostly a smart privacy tool, not a safe replacement for real network security. The ESP32-S3 setup described here is not routing all of your internet traffic in the way a home router or firewall does. It is acting as a DNS sinkhole: it answers domain-name lookups and blocks requests to known ad, tracking, phishing, or malware domains by returning 0.0.0.0. In that role, a $10 board can be remarkably effective. It is cheap, uses very little power, works across phones, TVs, and IoT devices, and can reduce bandwidth use on slow connections. The security risk is less about the hardware price and more about what the device can and cannot do. This kind of blocker does not inspect traffic, replace a firewall, or stop threats that use hardcoded IP addresses. It also has important blind spots: no current IPv6 support in this project, YouTube ads still get through, and browsers or apps using encrypted DNS such as DoH or DoT can bypass it unless you disable those features or block them at the router. There is also operational risk. If the device fails or is misconfigured, DNS can break for the whole home. Open-source firmware is only as trustworthy as its code and maintenance, so users should verify the project, keep it updated, and avoid exposing any admin interface beyond the local network. Used as a narrow, local DNS filter, it is a clever privacy hack. Treated as a full security appliance, it is not enough.

1 articles · Updated · ZDNet · Jun 17

$7 ESP32-S3 board was used to create a DNS sinkhole that blocks ads before they download, aimed at conserving bandwidth without using a Raspberry Pi.
ESP32_AdBlocker runs on the board after being flashed through Arduino IDE, then filters DNS requests from devices and redirects blocked domains to 0.0.0.0.
Setup requires connecting to the board's temporary Wi-Fi, entering the home network credentials, choosing a blocklist, and pointing devices' DNS settings to 192.168.4.1.
The approach trades capability for cost and power use: the ESP32-S3 uses milliwatts and no microSD card, while a Raspberry Pi Zero 2 W setup starts around $15 plus storage.
Limits remain: it cannot block YouTube ads served from the same domain as videos and does not work with newer IPv6 addresses, making it better for temporary or lightweight use.