What is the name of the technology for requesting authentication when connecting to Wi-Fi?

Question

linux

When connecting to a wi-fi network at an airport, etc. a window immediately pops up where it offers to authenticate (the window appears by itself, starting the default browser). As I understand it, this is a wi-fi protocol that launches a browser for authorization. Tell me, please, what is the name of this protocol and how can it be implemented on unix.
The most important task is to immediately open a browser with a specific site when connected to wi-fi.

Answer 1

This is called hotspot or captive portal.

Answer 2

It's called RADIUS -- look it up on google. I have never raised it myself, but it works like this: it redirects users to a web service, where they are being tested. With all the consequences: they can be recognized, taken into account, limited, asked questions and so on..

Answer 3

This is called Captive Portal Detection An Android
device, for example, when connected to a wifi network, tries to open a page at connectivitycheck.gstatic.com/generate_204
If at this moment you intercept this request and redirect to your page with an HTTP/1.1 511 header, then the device will open this page of yours with the wording "Sign in to Wi-Fi network".