Cloned MAC address?

Bill Stanley bstanle at
Fri Aug 12 17:46:28 UTC 2011

On 08/12/2011 01:26 AM, Nils Kassube wrote:
> Bill Stanley wrote:
>> I was exploring the GNOME desktop and found something interesting.
>> When right clicking the Network management Applet icon there is an
>> item that says "Edit Connections".  I clicked on this and then on
>> one of the items, "Auto Eth0", which the applet says is never used.
>> There is nothing interesting yet but one of the options is "cloned
>> MAC address". Is a different MAC address reported to the Internet
>> instead of the actual MAC address?  I don't intend to do anything or
>> do any editing of the settings, I am just curious.
> Usually a hardware interface has a preset MAC address. However for most
> (all?) interfaces you can overwrite the MAC address by software. This is
> particularly useful if your ISP has a setup where you can only connect
> with a specific MAC address. Then, if you replace the hardware that
> connects to your ISP, you could set the new hardware to that previously
> used MAC address to connect again without calling them to request a
> change in their setup for your new hardware.
> OTOH, this feature is also the reason why MAC address filters for your
> WLAN router are useless - everybody can fake the address of a station
> that is allowed by the filter.
> Nils

That is exactly what I thought!  In essence, you are not giving to the 
Internet the true MAC address of the network hardware.  Of course this 
could be done for a good reason or for some nefarious reason.

Bill Stanley

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