Can I get the original MAC address after it has been changed?

Question

I am using some linux machines that have had their MAC address changed. I would like to be able to read it back with a shell script.

Is the original MAC address stored anywhere except the sticker on the box? How do I bring back the original hardware address?

Answer 1

you can check you dmesg logs it will report the hardware MAC address as seen on boot.

on one of my boxes the output looks like:

gbeech@ny-man01:~$ dmesg | grep eth0
[    6.533181] eth0: Broadcom NetXtreme II BCM5709 1000Base-T (C0) PCI Express found at mem d6000000, IRQ 36, node addr 00:21:9b:a0:b7:cc

what you are interested in is the node addr 00:21:9b:a0:b7:cc bit at the end

Answer 2

Might be on the physical card, or etched onto the motherboard. I doubt you can access it from a script however.