MAC Address Spoofing unter OS X:
There are various reasons why one might need to spoof ones MAC address. For example, your ISP may have bound your connection to your MAC address, and then you had to change your network card because the old one was fried by a lightning strike. Another reason is privacy. You may want to change your MAC address if you’re surfing the net from a coffee shop with free wifi to make sure no one sniffing the network can identify you. Whatever the reason, the actual commands to (temporarily) change your MAC address are quite straightforward.
Before you do anything, make sure the port is up:
sudo ifconfig ≶iface> up
For the ethernet port:
sudo ifconfig en0 ether ≶new MAC address>
Once you’ve disconnected, just run the command as above, but for the en1 interface:
sudo ifconfig en1 ether ≶new MAC address>