Restricting access to Specific ports.

[loyalty]

I have a Host on a remote external Network providing replies to request from Users on my Network, I have an extended access-list in place that restricts access from the Host only to these specific Users. is it posible to restict access from this external host on the Switch ports these Users are connected to as well.

[DALE FRANCIS]

You could look at using 802.1x Authentication but you will need RADIUS etc, however there are topological limitations, but this is a growing area. Other than that i would suggest to ties a port down by MAC but the MAC in your case will change... so at the end of the day, it does not seem possible.