Developing a s/w

i'm developing a s/w to b implemented on a LAN for my final
sem project.I'm using VB6 as front end and MS SQL Sever2000
as back end.My s/w will b such that : suppose the server is
having internet connectivity.Sitting on a client m/c if i
want to access the internet, the user have to go thru my
s/w which gives a login dialogue box.The sever keeps a db
of the users...if the login is succesful, then the server
will give permission to the internet connectivity to be
shared.Now, my problem is that how can i associate that
server sharing permission with the coding of my
application?...(my s/w also has provision for unregistered
users to be registered based on some constraints such as
location.)I can send my code if its needed.