TrollBridge is a set of scripts that allows you to build a custom network authentication.
It can be used to to setup a network hot-spot for your business, school or home. The only authorization methods currently available are a skeleton username/password example, and an example using iButton devices. When a unknown MAC addresses tries to make a connection to the protected network the iptables rules redirect any access (web or otherwise) to port 5280 where the Apache server then displays the authentication page. MAC addresses are used to keep track of authorized users, so this system is susceptible the MAC is spoofed.
The scripts are not 'plug and play', you will need to customize them for your unique situation, as well as modify your iptables settings and add a virtual host to the Apache web server. If you need help you can ask on the TrollBridge support list