Re: ethtool documentation

From: Abraham vd Merwe (
Date: Wed Aug 07 2002 - 07:05:06 EST

Hi Richard!

This whole argument is useless anyway. The ethtool API already allows
userland apps to change the eeprom, so you can already change the MAC
address (which I also believe is the way it should be, because that allows
manufacturers to program the MAC address without requiring additional

People don't like to break their hardware for the fun of it. You don't see
people reprogramming their memory eeproms using the i2c code, but the
functionality is there. I think ripping out all kinds of functionality just
because there is a slight chance of some stupid person trashing his/her
hardware is unproductive and contrary to the spirit of open and free software.

> > > If you let a user write to this area, you will allow the user
> > > to destroy the connectivity on a LAN.
> > >
> > > 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.
> >
> > Dick, this "weapon" has been the in the hands of admins and evil-doers for
> > YEARS!
> >
> > It is called /sbin/ifconfig
> >
> > With this evil command nearly any NIC can masquerade as any one of
> > ~281474976710656 possible IEEE Station Addresses. This weapon of
> > destruction has seen wide spread proliferation across most Unix varients.
> > Human sacrifice, dogs and cats living together, mass hysteria!
> >
> > Err, no wait.
> >
> > The sky is not falling, you protest too much.
> >
> > Dax Kelson
> >
> That capability is not permanent. If you let users write to the
> SEEPROM, permanently changing the IEEE Station Address, you have
> let users permanently break their network boards. I do protest
> when this capability is in the kernel.
> Anybody, who knows how can, write a driver that can destroy their
> disk drives, their modems, their audio boards, their screen-cards,
> their motherboards, ...the list goes on..., because EEPROMS are
> being used now days. But, you don't put that capability in the
> kernel as a default.
> If you do, you get complaints from those who have had the misfortune of
> being interrogated by lawyers.
> Also, if you want to destroy Ethernet, mucking with the MAC address
> is an easy way to do it.


Regards Abraham

Luck can't last a lifetime, unless you die young. -- Russell Banks

__________________________________________________________ Abraham vd Merwe - 2d3D, Inc.

Device Driver Development, Outsourcing, Embedded Systems

Cell: +27 82 565 4451 Snailmail: Tel: +27 21 761 7549 Block C, Aintree Park Fax: +27 21 761 7648 Doncaster Road Email: Kenilworth, 7700 Http: South Africa

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