I have three computers all wired into my router. The box I'm posting this from is running Ubuntu 11.10, and another machine is running Xubuntu 11.10 Both connected automatically when the ethernet cable was plugged in. However, my wife's computer, running Ubuntu 10.10, cannot connect to the eth0 connection. I checked the connection's properties and the MAC address is all zeroes! How do I determine what numbers to plug into the MAC Address field?