[niij]

> Something along the lines of arbitrary subdomains which represent the request payload, and a custom nameserver that returns responses via the TXT record or something. Anyway…).

This is iodine. https://github.com/yarrick/iodine

[_kidlike]

I did something similar ~12 years ago, albeit it was just http(a) over UDP tunneling, and not DNS specifically.

I had to spend 8 hours in Stansted airport, and I managed to setup the tunnel while in the time limit of the free WiFi (I think it was 30'). It felt good, haha.