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Date: Sun, 12 Jan 2014 08:40:01 +1100
Subject: Re: How to get Mac address of ethernet port?
From: Chris Angelico <rosuav@gmail.com>
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On Sun, Jan 12, 2014 at 3:29 AM, Roy Smith <roy@panix.com> wrote:
> If you don't believe that two machines can have the same MAC address,
> look up Hot Standby Router Protocol.  And if you don't believe a machine
> can ignore the BIA and assign a new MAC address in software, look up
> Decnet <insert derogatory gesture with sound effect here>.

Most people shouldn't have to worry about MAC address
duplication/collision on the same subnet (I used MACs as a means of
guaranteeing uniqueness among a pool of application servers, for
instance), but MAC switching in software can occur in a typical home
internet connection scenario. We had a connection set up a few years
ago where the ISP tech recorded the source MAC into the far end, and
only that MAC would work - so when I stuck in a different router, I
needed to switch it to the old MAC before it could establish a
connection. Stupid? Yes. Unusual? I hope so, but still more likely
than coming across DECnet in a typical home!

ChrisA