>>    The idea is that promiscuous mode is often used to diagnose network
>> problems, and thus should allow certain types of shouldn't-happen packets
>> through (such as too small).
>>    The 0x55 is the automatic padding byte that the interface adds to fill
>> out a frame, so nothing mysterious there.
>
>Yes, but tcpdump is also used for many things besides that and its
>pretty annoying to have these bad frames interleaved between valid
>ones.
>
>Of the machines/arch's/drivers I tested only fxp did this bizarreness.

   The 'ed' driver that I wrote for the National 8390 and compatible chips
also does this, as does the correspnding 'dp8390' driver in NetBSD. There
may be others.

>Why not use a link flag for this specific application?

   Probably not a bad idea, but there isn't anything defined in the current
API to support it and there used to be a shortage of bits in struct ifnet.
Both are pretty lame excuses, though.

-DG

David Greenman
Co-founder/Principal Architect, The FreeBSD Project - http://www.freebsd.org
Creator of high-performance Internet servers - http://www.terasolutions.com