interface_detect is a script to help you detect which ethernet interface matches which physical port How to use. 1) Disconnect all ethernet cables connected to any ethernet physical port 2) Run "sudo su" to take root privileges 2) Make sure the /etc/network/interfaces doesn't contain any configurations for any ethernet interface except loop back. If it is not empty please make a safe copy and create a new one with no configurations. Reboot the server or restart interfaces. 3) Run ifconfig -a to show all the available interfaces and note down the higher interface number. 4) Connect a network cable connected to the network to any physical port you want to find out the interface and run the script with first argument the number of the higher interface -1. For example if "ifconfig -a" returns "eth0, eth1, eth3, eth12" you run the script ./detect_interface 11 The script should return the ethernet interface listening to the specific port as well as the mac address.