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Re: [LUG] MAC address on Android


On 13/01/14 17:55, Gordon Henderson wrote:
> On Mon, 13 Jan 2014, George Parker wrote:
>> Thanks to you all but I think that Grant has the answer here.  I am
>> looking at my router client list and if I switch off the wi-fi on my
>> phone, then back on again it reconnects with a different MAC.
> What a strange phone.
> The whole point of the MAC is that it never changes - it's unique for
> each device. It's not supposed to change. The manufacturer is supposed
> to assign a unique MAC for every device they make - and once upon a time
> I was the person responsible in a company making network devices to
> ensure that all our products did get a unique MAC...
> I've just checked with 2 Android phones of mine - they keep the same MAC
> between reboots - which is as intended.
> If yours changes, then its really really weird - and what protections
> are there to make sure no 2 devices on the same LAN have the same MAC?
> MACs on servers are often used to bind licenses too - and while it's
> possible to change a MAC it's really not "the done thing"....
> Gordon

This is Nexus specific, but quick googling shows this is actually not
that uncommon:


Is the first part of your randomised MAC always 00:90:4C with just the
last three octets changing?

It looks like some moron engineer (maybe at Google) included some code
to once, and once only, generate a psuedo-random MAC and write it the
file /system/wifi/softmac, probably during the phone's initial
registration. They obviously broke something and some phones are just
running that code snippet every time and not permanently storing the
initially generated value.

Some people are reporting success after following the advice here:


But I would just instantly return any network capable device that was
randomly regenerating MACs as not fit for purpose and be done with it.
How does stuff like this make it past QA?


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