When a user plugs the laptop into our network, it is going to be local, so it won't hop around the Internet prior to that. For your approach, does that mean I have to constantly monitor the dhcp lease file (via some kind of loop/daemon)? What I really want to do is trigger something and grab the user's MAC and see if the laptop is authorized. I know grab MAC address using ipconfig, but I want to automate this part. Thakns.