How to Change MAC Address (MAC Spoofing) in BSD or FreeBSD

Issue the following commands in shell:
ifconfig <interface> down

ifconfig <interface> <class> <MAC address>

ifconfig <interface> up
First command brings down the network interface (optional), second command change its MAC address while third command bring up the interface again (optional). For example, the command looks lik “ifconfig xl0 link 1A:2B:3C:4D:5E:6F” or “ifconfig fxp0 ether 1A:2B:3C:4D:5E:6F”