MAC (Media Access Control)
addresses are permanent by design, several mechanisms allow
modification, or “spoofing”, of the MAC address that is reported by the
operating system. This can be useful for privacy reasons, for instance
when connecting to a Wi-Fi hotspot, or to ensure interoperability. Some
internet service providers bind their service to a specific MAC address;
if the user then changes their network card or intends to install a
router, the service won’t work anymore. Changing the MAC address of the
new interface will solve the problem. Similarly, some software licenses
are bound to a specific MAC address. Changing the MAC address in this
way is not permanent: after a reboot, it will revert to the MAC address
physically stored in the card. A MAC address is 48 bits in length.
A MAC address is a physical hardware
address assigned to each device that has the capability of connecting to
a network. The internet is nothing more than a large network. The MAC
address is something that is assigned in the chip on the device and is
not something the user can change.
As a MAC address can be changed, it can
be unwise to rely on this as a single method of authentication. IEEE
802.1x is an emerging standard better suited to authenticating devices
at a low level.
Types of MAC address:
Unicast address : An address for a specific computer.
Multicast address : An address for a specific group of computers in network.
Broadcast address : An address for all computers in network.
How Can U Change MAC Address:
Windows
Under Windows XP, the MAC address can be
changed in the Ethernet adapter’s Properties menu, in the Advanced tab,
as “MAC Address”, “Locally Administered Address”, “Ethernet Address” or
“Network Address”. The exact name depends on the Ethernet driver used;
not all drivers support changing the MAC address in this way.
However, a better solution – requiring
Administrative User Rights – is to pass over the System Registry Keys
under
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}.
Here settings for each network interface can be found. The contents of
the string value called ‘NetworkAddress’ will be used to set the MAC
address of the adapter when next it is enabled. Resetting the adapter
can be accomplished in script with the freely available command line
utility devcon from Microsoft, or from the adapters context menu in the
Network Connections control panel applet.
There is a nice tool to change the MAC
address for all cards (even those that can’t be changed through the
adapter’s Properties menu): SMAC MAC Address Changer.
Note: to check your MAC address easily
on a Windows XP box, go to Run, type CMD, then type “ipconfig /all”
without quotation in the command prompt. The number under physical
address is the MAC address. If multiple IP are displayed, you should
look under the label “Ethernet adapter x”, where x is the name of your
connection (which is Local Area Connection by default).
Router
The method to change the MAC address of a
router varies with the router. Not all routers have the ability to
change their MAC address. The feature is often referred to as “clone MAC
address”. This take the MAC address of one of the machine on your
network and replaces the router’s existing MAC address with it. Some
support the option to manually enter the MAC address.
How to change a MAC address in Linux
To change your MAC address in Linux (and most *nix system) is easy. All it takes is two easy to script commands:
ifconfig eth0 down hw ether 00:00:00:00:00:01
ifconfig eth0 up
These two little commands would set your
eth0 interface to use the MAC 00:00:00:00:00:01. Just plug in the NIC
you want to set and the MAC address you want to use into the commands
above and your done. Changing your MAC address is one of those things
that is much easier to do in Linux then under Windows.
