Finding original MAC address from Hardware itself

Certainly in ethtool 3.1 you can just print the address:ethtool -P|--show-permaddr DEVNAME Show permanent hardware address

e.g.

ethtool -P eth0

Permanent address: 94:de:80:6a:21:25

Try cat /sys/class/net/eth0/address or cat /sys/class/net/em1/address if using Fedora. It should work.

The original answer is here: Notes of a Systems Admin

The only way to find the original MAC address is to use the same method the network card driver does - unfortunately, I don't believe there is a generic way to tell the driver to provide it's MAC address "as provided by the hardware". Of course, there are cases where there isn't a hardware network card for that particular interface - virtual network drivers for virtualization and when using bridges and software switches for example.

And of course, the hardware may be such that you can't actually read the "original" MAC address when it has been overwritten by software, because there is only one set of registers for the MAC address itself.

I had a quick look at the pcnet32.c drivers (because it's one of the models of network card that I have a rough idea how it works and where the different registers are, etc, so I can see what it does). As far as I can see, it supports no method of actually asking "what is your PROM ethernet address" - the MAC address is read out during the "probe1" section of the module initialization, and stored away. No further access to those hardware registers is made.