Sometimes you need to connect to a network, which is designed to only allow connections from certain network interface cards, filtered by their MAC address. This filtering can be avoided by changing or spoofing your computer’s MAC.

sudo ifconfig en0 lladdr 00:00:00:00:00:00 # <- the new MAC address
sudo ifconfig en0 down
sudo ifconfig en0 up

Your original Media Access Control address will be restored after a reboot.