Be sure you have root credentials! How to? Enable root .
We are going to modify a file. So use putty or winscp to connect to your xbmc center.
After login, using your root credentials. Navigate to /etc/network and there you find the interfaces file.
If you would like to have a copy of the original file. Feel free to make one.
After that copy the settings below and paste it into your interfaces file.
Of cause you need to modify the ip addresses.
iface eth0 inet static
Save the file.
Reboot your system “shutdown –r now”