Subject: Re: bpf write() to local host
To: David Laight <>
From: Curt Sampson <>
List: tech-net
Date: 01/23/2003 21:20:38
On Thu, 23 Jan 2003, David Laight wrote:

> > > Adding an alias really requires that the ethernet hardare support
> > > multiple MAC addresses, some modern ones do.
> >
> > All that I have ever seen do. You have to have this to support multicast.
> No you don't...

It really depends on what you mean by "support multiple MAC addresses."
I mean "there is some way of getting a card to listen to more than just
the broadcast and its own address."

> Full promiscuous and software filtering can stop an otherwise
> working card being able to do anything useful.

Sure. Or it might not. Depending on the card.

I run plenty of 100base-T cards on firewalls and routers for long
periods of time without performance problems.

> It is a bad, bad idea.

It's a bad, bad idea on some hardware, yes. But by adding this feature,
nobody is making you use it on a 486 with a crappy ISA ethernet card
attached to a busy network.

Are you really arguing against the inclusion of the ability to change
MAC address based on the performance reasons you've given? If not, let's
just stop arguing and wasting time.

Curt Sampson  <>   +81 90 7737 2974
    Don't you know, in this new Dark Age, we're all light.  --XTC