Mods - please delete

OK, this was a shock: I have a 19.07.7 based custom build for x86_64 that I'm trying to refine with my settings and packages. The hardware is a Qotom Q330G4 i3 2GB/16GB SSD with four ports. I installed a build I made last week, and the MAC address of eth0 was 40:62:31:16:6B:ED. Then I erased the drive, and flashed a new build I made yesterday (only a minor etc/config file change), and today it has a MAC of 40:62:31:14:AA:25.

The /etc/config/network does NOT set an option for MAC on the interfaces. And I need it to stay that way, as I plan to deploy the build on a handful of units for family/freinds.

I know that unlike commercial routers with ROM, the x86 does not have a place to read a unique root MAC from, so the question is: where and how does it come up with one?

And more importantly, how to make it unique and durable for a given piece of hardware?

I poked around for something unique and durable to each box, and found that the EUFI DMI (which otherwise is so bland they don't even fill in vendor info), there is a (hopefully) unique UUID to be found at sys/devices/virtual/dmi/id/product_uuid
My thought was that could be used in an algorithm to generate a MAC that remains consistent to that uuid. But where/how?

Thanks in advance for the help.

Each port has a ROM (inside the Ethernet chip or attached to it) with a "factory" MAC for it. You're probably seeing the MAC change because the ports were enumerated in a different order.

thanks for the reply, you are correct.

I'm inattentive and swapped hardware late yesterday and forgot when I ran my tests this morning. So of course the MACs are different, it not the same box.

Mods, please delete the thread if I can't manage to

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