getting IP from AP
 

Here's what I need, I have seen at airports, the WiFi AP, include client notebook, the screen for a list of free AP, and when you enter the browser, load up an address, usually some ads, or field to register / login, after confirmation received the free internet access, I'm interested how this works, using the service, I get it to the router in the story, this should be do Mikrotik, but I need for LAN play with Squid proxy, and pushing the entire transport across it

Sorry for bad English:)

The ones here usually work this way:

Dns is redirected to their internal dns server, which blocks many sites (cache stuffed with redirects to their 'blocked' page). You sign in and have to use their dns, whatever that is. That's probably where you are tripping up. often a reboot is needed to get going. You get to surf - all other services are doubtful