Hi Friend,
Do you have any managable cisco switch on which all your clients are connected?
Can you brief more about your setup? Does all clients get an ip adress form DHCP and you want only specific machines to access the network? Or you want only specific machines with their mac address to get an ip address from DHCP?
If you can explain more about your setup may be someone here can provide you with some solution.
Regards,
Ankur