Re: ethtool documentation

From: Randy.Dunlap (
Date: Tue Aug 06 2002 - 15:04:43 EST

On Tue, 6 Aug 2002, Richard B. Johnson wrote:

| On Tue, 6 Aug 2002, Chris Friesen wrote:
| > "Richard B. Johnson" wrote:
| >
| > > Because of this, there is no such thing as 'unused eeprom space' in
| > > the Ethernet Controllers. Be careful about putting this weapon in
| > > the hands of the 'public'. All you need is for one Linux Machine
| > > on a LAN to end up with the same IEEE Station Address as another
| > > on that LAN and connectivity to everything on that segment will
| > > stop. You do this once at an important site and Linux will get a
| > > very black eye.
| >
| > Can't we already tell cards (some of them anyway) what MAC address to use when
| > sending packets? This doesn't overwrite the EEPROM, but it does last for that
| > session...
| >
| > Chris
| Sure you can. And it was assumed that the MAC address provided by
| the manufacturer would always be used by the software for the MAC
| address on the wire. However, 'software engineers' have decided

Assumed by whom? IEEE allows locally administered addresses,
and most NIC mfrs that I know of support/allow them.

| that they don't have to follow the rules, so they provide hooks
| so you can use a MAC address of anything. They even call it
| "Local Administration...", which decoded means; "Screw the
| committee".



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