How to intercept a WiFi connection?

Question

Programming

I can not qualitatively formulate the question, so I will try to describe the problem.
There is a hotel in town A with free WiFi hotspots on the floors.
It is necessary to make it so that the first time you connect to the network, the hotel's start page opens, and then the user can do whatever he wants.
How to implement it correctly? There are accesses to routers, including the possibility of replacing routers with such that they can be reflashed by OpenWrt. But perhaps there are other ways to solve this problem?

Answer 1

sho something 500 habr crashes Kosher
- *wrt/tomato Krivoruko's firmware -
via squid - here are examples search for "captive portal"

Answer 2

This is called captive portal.
You can try to do it manually, but it's better to use a ready-made one. For example, here it is: pfsense.org . Here it is written in more detail.

Answer 3

On Mikrotiks in hotspot, it is easy to make any start page, including authorization. If this is openwrt, then you should also look towards hotspot. Authorization can not be screwed, but the start page is probably there.