Every Ethernet card has a unique MAC address written into it at the time it was manufactured. However, there are a number of reasons why the MAC address should be changed. It is entirely up to the user.
Changing to Work With ISP
Most Internet Service Providers (ISPs) assign one permanent IP address per client. However, this method is an ineffective approach, because IP addresses are presently in short supply. As an alternative, some ISPs make sure that each client has one dynamic address that may change each time the client hooks up to the Web. They then register and track the MAC addresses of the device connected to the ISP.
ISPs monitor the MAC address of clients with a broadband router, a cable modem, or the computer hosting the Internet connection. ISPs ensure that the MAC address of equipments used always matches the registered value. If a client replaces that device or its network adapter, the MAC address will no longer match the registered value.
Changing a MAC Address Through Cloning
Requesting for ISPs to update the MAC Address will take time, and while actions are not yet taken, the user cannot surf the Internet.
A better means to promptly work around this trouble is to change the MAC address on the new device so that it corresponds to the original device. Cloning is the process wherein the MAC address is emulated through the software. ISPs see that the emulated MAC address is identical to the original hardware address. Many broadband routers support cloning as an advanced configuration choice. The specific cloning procedure will depend on the type of router to be used.
Changing Through the Operating System
The specific procedure to change the MAC address depends on each Operating System.
In Microsoft Windows, the MAC address is saved in a registry key. Find the registry key with ‘regedit’, and then change it. With Windows XP, the MAC address on some network cards can be changed through the Advance tab in the Properties menu of the network adapter. A software utility program is designed to be more dependable and is a much easier means to change the MAC address. Macshift is an example.
In Linux, the MAC address can be changed by using the GNU MAC Changer or by using ‘ifconfig <interface>hw<class><address>’.
In HP-UX, Networking and Communications should be used. Click on the ‘Interface’, and then go to ‘Action.’ Click on ‘Modify,’ and then ‘Advanced options.’