Binding MAC address with username

Hello, For my setup, I'd like to bind a MAC address to a specific user when it first login. For exemple, user 1 connects from computer 00:11:22:33:44:55. I'd like the system to remember this MAC address, so that the next time the user reuses this same computer, it does not asks to connect again. This way, the users would rather be the mac addresses. Another solution I think would be to store the MAC address as a new user in the same group as user 1. Which way would be the best? Thanks, Acrilex