[CentOS] Captive Portal

Hi All, I'm trying to set up a Captive Portal using a Centos6 box. I've been experimenting with WiFiDog but it looks like development has faltered and I'm chasing my tail getting all the bits of PHP together for it to run. Some bits I've got look like Alpha code.

What I'm trying to accomplish is a a simple firewall type system for a public WiFi, that redirects users to a Web page when they first connect, accepts some credentials such as an e-mail address and allows them access to the 'net. Other features like limiting the volume of download and some kind of porn filter would be good.

Anyone doing anything like this care to share what they use.

Many thanks

Ken