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Re: how to change mac address back after decnet changed it?

On Mon, 2011-09-05 at 13:29 +0100, Darac Marjal wrote:
> According to wikipedia[1], this is a feature, not a bug:
> | The Ethernet implementation was unusual in that the software changed
> | the physical address of the Ethernet interface on the network to
> | AA-00-04-00-xx-yy where xx-yy reflected the DECnet network address of
> | the host. This allowed ARP-less LAN operation because the LAN address
> | could be deduced from the DECnet address. This precluded connecting two
> | NICs from the same DECnet node onto the same LAN segment, however.
> So your DECnet address would be 0x0A04.

I imagine this confuses many network switches when unsuspecting users
pulled in these updates?

> > 
> > So how do I get rid of that aa:00:04:00:0a:04 address? And getting the
> > old ones back, note that I do not remember the old ones, nor do I have
> > them all written out somewhere.
> You should be able to set the address with:
> $ ifconfig ethN hw ether aa:bb:cc:dd:ee:ff
> The value of the address doesn't really matter so long as it's unique on
> your ethernet segment (i.e. your network). Then again, if you're doing
> some sort of bonding or balancing, it doesn't even have to be unique.

Thanks, I was able to find the old hw addresses
in /etc/udev/rules.d/70-persistent-net.rule (thanks Tom H for the tip),
unfortunately the ifconfig method does not persist after reboot.
And I doubt the method Tom H suggested would work since the old address
is still in the udev file, not the new decnet address.

Why would one want to have this actually? Personally I don't see the
advantage it gives me over my existing network configuration using
mostly tcp/ip over ethernet. Just curious. Also according to the
wikipedia link you gave, decnet code in the kernel was orphaned with
2.6.33, I don't know if that is still the case.

Kind regards,

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