/etc/udev/rules.d/70-persistent-net.rules defines the names for network interfaces. You can modify it, as long as you keep each rule on a single line, and change only the value of the NAME= key (as per the file). e.g.
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="XX:XX:XX:XX:XX:XX", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"
So change the NAME from eth1 to whatever you need. In my case it became wan0 for internet facing interface.
