To turn your ESP32 into a network-based DNS request killer, you'll need an open-source project on GitHub called ESP32_AdBlocker. This allows you to upload Arduino code to an ESP32 controller with PSRAM memory, then connect your router to it. This gives you a hardware-based ad blocker that costs less than your morning cup of coffee.
At its core, ESP32_AdBlocker works exactly like Pi-hole. When any device on your network tries to access a specific domain, such as an ad server or an in-app tracker, it first asks a DNS server to translate the domain into an IP address. Regular routers forward this request to an ISP or external DNS. With the ESP32 installed, however, any domains on the block list are returned with the address 0.0.0.0. The connection is immediately dropped, the device does not load the ad, and does not consume network bandwidth, regardless of which device it is.
The project uses the built-in PSRAM memory to store the list of blocked domains. Domain lookups are extremely fast and typically take less than 50 to 100 microseconds on a standard ESP32 chip, which is faster than communicating with external DNS servers. Any requests that are not blocked are forwarded to your chosen external DNS server without any problems.
The main hardware requirement is the presence of PSRAM memory. ESP32 boards are available in versions with 4 MB or 8 MB of PSRAM. It is recommended to use the 8 MB version, such as the ESP32-S3 model, which costs between 5 euros and 10 euros. This allows you to store the entire consolidated list of blocked domains (such as Steven Black) directly in memory. In the 4 MB version, the list is automatically shortened, but still offers good protection. With this project, there is no need to buy microSD cards, maintain the operating system or install security patches. The total cost, including USB cable and charger, does not exceed 15 euros.
Installation is done through the free Arduino IDE. After downloading the files from GitHub, you choose the appropriate partition scheme that allocates PSRAM memory, and write the program to the board. When you first start the ESP32 acts as a Wi-Fi access point. You connect to the network, go to 192.168.4.1, and enter your home Wi-Fi information and the URL of your blocked domains list (in HOSTS or AdBlock format). The last step is to set a static IP address for your board and enter this IP as the default DNS server in your router settings.
The web interface allows you to monitor downloads and analyze blocked domains in real time. Future updates only transfer data differences, which speeds up performance. Although the system does not offer advanced graphs or a DHCP server function like Pi-hole, it is an excellent, economical and simple solution against trackers.<\/p>\n