Symptoms
The Debian Xen Virtual Machine (XenVM) fails to obtain an IP address or the operating system reports that the eth0 interface was not found.
Cause
Debian uses udev to manage hot-pluggable devices. When a cloned XenVM or imported Debian XenVM is started, it is most likely that network interface names get changed and have a MAC address different than the Virtual Network interface card (NIC) attached to the XenVM.
Resolution
1. Edit the file /etc/udev/rules.d/z25_persistent-net.rules and delete all the occurrences of the lines like the one given below:
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:16:3e:aa:f9:f8", NAME="eth0
2. Save the file and quit the editor.
3. Restart the Debian XenVM
Now you should be able to see the network interfaces in the proper order and with correct MAC addresses.
