I have an ESP32 wroom32 that has WiFi internally and an ethernet port. I want to be able to connect my phone to the WiFi and access a webserver running on the ethernet port. Schematically this looks like:

PC ----------------------- ETH (ESP32) <----NAT?----> Wifi (ESP32)------------ Phone

The PC has static IP: ETH (ESP32) has static ip Wifi (ESP) has dhcp enabled, subnet: 192.168.4.x

I am able to configure the Wifi and the ethernet part to initialize. The ETH side has a static ip and the Wifi side has DHCP to assign an IP to the phone.

I use ESP-IDF running RTOS framework to develop my application. And I have been searching the internet for possible solutions to this problem. I have found suggestions that to connect both interfaces (ETH and Wifi) I need something like NAT running on the ESP. However there is no current implementation of this.

I only want to access a specif webserver page running on the PC (access through, this makes me think that it should be possible to have a very simple forwarding function that forwards between Wifi and ETH.

At the moment I am not sure how to start. If my idea is even possible or if there are alternatives to implement what I want.

Final: I have been able to implement the ETH2Wifi example, but this connect both interfaces and disabling the functionality of the access pint

  • 1
    Why do you think you need NAT (Network Address Translation)? this is basic IP routing. Also why bother with the ESP32 when you can just stick a USB wifi adapter in the PC (assuming it doesn't already have a Wifi adapter)
    – hardillb
    Feb 1, 2019 at 16:17
  • I will look into ip routing but I thought that to transfer packets between interfaces you need more than routing. For simplicity I namend it above a pc, however in reality it is another embedded device that cannot be changed. It is a sensor measuring some values. I want to add some other sensors to it with the ESP + wifi connection on that is on the ESP.
    – Steven
    Feb 3, 2019 at 12:34


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