Squid proxy with user authentication and user rights
 

The scenario I am faced with is this. I was told to setup a proxy server, I am using RH9 and have installed two nics, one for my ASDL connection and one for the internal network. The internal network's PC's are windows machines. The windows machines must log into the linux server. I must also be able to assign certain rights to each user like to limit each user to download only a certain amount of MB per month. For users to login to the linux server I know that I must use proxy authentication but I don't know how to do it. Any help will be great.