How to password protect the internet access on a client system in LAN please reply me
Give more information. As far as the statement goes all i can understand is that there is a established lan network containing view computers. One of the computer might have internet connectivity through which you want to share internet to some or all the machines. Is that the case?
If yes then on the router create a filter list using mac address and enable HTTP service for them and decline it for the rest of the lan addresses. In this way you would be able to keep all the computers on lan but based on MAC address some systems will get internet access.