http://en.wikipedia.org/wiki/Captive_portal
Captive portals are used at many Wi-Fi hotspots, and can be used to control wired access (e.g. apartment houses, hotel rooms, business centers, "open" Ethernet jacks) as well.
- Redirection by HTTP
- ICMP redirect
- Redirection by DNS
RFC3576:
從radius sever發送到NAS上的radius消息。
Disconnect messages cause a user session to be terminated immediately, whereas Change-of-Authorization CoA messages modify session authorization attributes such as data filters.