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).
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.