How can i manage Internet Connection Sharing???

In my office there is 11 PC. All are connected by HUB and creating a LAN. In my one PC there is USB DSL Router Network Device for connecting internet. My USB DSL Router Network Device share to LAN for using Internet of all computers.
Now how can i manage user-client authentication. When LAN PCs want to connect to internet Getaway authentication step must required at that time.
I don't want use any types of proxy software because it must required per computer settings.
Is there another way to solve my problem.

check your router there is built in security system if your router is from goood company you don't have to worry just click and apply options or for better management you must learn linux or xp server or for easy management buy good cable/dsl router

First of all, Internet Connection Sharing is designed for home use. Yes it can be effective in some instances for very small offices with 2-4 computers. In your scenario ICS is a really poor choice.

You should connect your DSL "modem" (DSL network bridge) directly to your wired or wireless router.

If you want authentication for each client system you will need a server. This is part of a network file server's task.

You can also limit the hours of the day, the bandwidth, and the sites visitable via the routers policies. This would be a poor substitute for a network file server though.

NO idea

The best program for doing this is WinProxy. It is installed on a computer that is hooked to the internet through 1 network card and another network card allow users to access the internet through the winproxy machine. It gives you amazing control and security. Go here for more information:
http://www.winproxy.com/products/winprox...