finding the Mac address from Ethernet shield (W5100)

hi guys:
I bought an Ethernet shield from ebay, when I receive it, i just realized that the shield doesn't have the MAC address on the back of shield. Is there anyone can help me to get the MAC address from the other ways?

Just make it up- as long as it's unique on your LAN it doesn't matter.

Most people seem to go with DEADBEEFFEED....

Thank you so much!!! :slight_smile: