DNS Server Example

This example demonstrates the use of the dns_server component to create a simple DNS server that responds to all queries with a single IP address. This is commonly used for captive portal implementations.

How to use example

Hardware Required

This example can be run on any ESP32 development board.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(Replace PORT with the name of the serial port to use.)

Example Output

[DNS Server Example/I][0.739]: Starting DNS Server Example
[DNS Server Example/I][0.739]: Starting WiFi AP: ESP-DNS-Test
[DNS Server Example/I][0.889]: WiFi AP started successfully
[DNS Server Example/I][0.889]: Connect to SSID: ESP-DNS-Test with password: testpassword
[DNS Server Example/I][0.899]: AP IP Address: 192.168.4.1
[DNS Server Example/I][0.899]: Starting DNS server on 192.168.4.1:53
[DNS Server Example/I][0.909]: DNS server started successfully
[DNS Server Example/I][0.909]: All DNS queries will resolve to: 192.168.4.1

Testing

Connect your phone or computer to the WiFi network “ESP-DNS-Test” with password “testpassword”
Try to ping any domain: ping google.com - all domains should resolve to 192.168.4.1
The captive portal detection should trigger automatically on most devices