I use DHCP Server and give IP Address base on MAC Address, then i do limitation (speed and access) on each IP Address
Example, for my boss i give more speed than others and give unlimited access to any website; but for other employee i give lower speed and limit their access, like cannot access friendster, facebook, myspace, etc.

But i worry, because someone can use MAC Address changer or change the IP to static IP Address.

So my question are:
1. How to detect client that use MAC Address Changer and will get the real MAC Address ?
2. How to protect, so only client that get IP Address from DHCP Server can access to the internet.. instead use static IP Address

Thanks,..

It is not possible on router to detect the things like this.

Some management switches allow to bind port/MAC-address, if it is not possible to use swich like this, but you are experiencing a lot of users who are changing MAC-addresses, you may go with PPPoE to secure the network and set queue per used UserName.