Get ethernet MAC address without powering on machine?

Brian D. Ropers-Huilman bropers at
Tue Jun 4 14:07:02 PDT 2002

Try popping open the case and looking at the device. Most Ethernet cards 
have a sticker with the pre-programmed MAC address on it.

As far as the "lights being on when the box is off," that's an artifact 
of the mobo and power supply. Older boxen don't act that way. It's a 
means to provide wake-on-LAN functionality.

On Tue, 4 Jun 2002 beowulf-admin at wrote:
> Howdy!
> We buy commodity boxes not only for our distributed computing needs (a
> render farm) but also for our desktops. We like to use kickstart to set
> up the box; we've honed the config for this pretty well. The problem is
> we need to get the MAC address prior to kickstarting the box so that we
> can give it a trusted IP which in turn allows it to NFS mount the disk
> where the RedHat distributions are.
> This leads me to my question: anyone know of a clever way to get the MAC
> address from an ethernet device without needing to power the machine up,
> load an OS, and probe around a bit. Having noted that ethernet devices
> often seem to display link and traffic lights even when the computer is
> powered down, I was thinking that a fairly special purpose device might
> be designed (RJ45 plug and simple digital readout kinda thing) which led
> me to wonder if such a device already exists.
> Has anyone ever seen or heard of such a thing?
> Thanks!
> --j

Brian D. Ropers-Huilman                   (225) 578-0461 (V)
Systems Administrator                     (225) 578-6400 (F)
Office of Computing Services              brian at
High Performance Computing      
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