Network Monitoring

[mhoby () iugaza edu]

Dear all,

I want to have a monitoring tool for viewing the active workstations and at the same time I want to have the ability to 
block any suspicious workstation from accessing the network (Based on IP address). I also would like to have a list of 
trusted MAC Addresses, so that any device that gets connected to the network without being in the trusted MACs will get 
blocked or if not, I get notified about the newly attached workstation...

Is their any software that can provide me with these requirements, or it might be a collection of software.. we are 
using Windows Server 2003 if that helps ..