I have one wired ethernet, to connect a PC with Linux Mint 10; sometimes this same cable i use to connect a netbook with Ubuntu Netbook 10.10.

Today i change the plug RJ-45 for a new one. The netbook get internet fast, but the Mint don't have internet. Cheking the configuration at the MINT, I saw that don't have MAC address; i get it in terminal with "ifconfig -a", but still don'tget internet. The plug RJ-45 is obvious that is fine, because the netbook get internet.