The physical MAC address will be permanently programmed to Ethernet adapter by the manufacturer. In other words, each Ethernet adapter carries an unique MAC address in the world.

However the operating systems like Windows or Linux can logically change the MAC address while the adapter in operation. If a MAC address is changed from the original physical MAC address to an another, it is called MAC address spoofing.

The following explains how a MAC address can be modified in various operating systems.

In Linux

[root@techpulp ~]# ifconfig eth0 down
[root@techpulp ~]# ifconfig eth0 hw ether 11:22:33:44:55:66

In FreeBSD,

[root@techpulp ~]# ifconfig nc0 ether 11:22:33:44:55:66

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