Media Access Control address (MAC address) is a unique identifier assigned to most network adapters or network interface cards (NICs) by the manufacturer for identification, and used in the Media Access Control protocol sub-layer. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number. It may also be known as an Ethernet Hardware Address (EHA), hardware address, adapter address, or physical address.
1. Change MAC Address in Linux ( CentOS, Debian, Fedora, RHEL, Slackware, SuSE, Ubuntu )
# ifconfig [interface name] down
# ifconfig [interface name] hw ether [new MAC address]
# ifconfig [interface name] up
# ifconfig eth0 down
# ifconfig eth0 hw ether 1A:2B:3C:4D:5E:6F
# ifconfig eth0 up