What I'm trying to find is something that would allow clients to connect to my lan, get an IP address from my server and not be able to use common protocol ports (ie: HTTP, HTTPS, FTP, MSN, POP, SMTP,VPN, etc.)
As soon as they open a web browser, they are directed to a login page or prompt that requires to enter a UID/PASS. As soon as they are authenticated, rules on the firewall are changed to allow their IP to connect to the Net with a timeout value (~60 min).