Subject: Re: a remote user can check promiscuous mode
To: Andrew Brown <email@example.com>
From: Justin C. Walker <firstname.lastname@example.org>
Date: 01/19/2000 19:53:51
> From: Andrew Brown <email@example.com>
> Date: 2000-01-19 13:27:14 -0800
> To: Matthias Drochner <M.Drochner@fz-juelich.de>
> Subject: Re: a remote user can check promiscuous mode
> Cc: Ignatios Souvatzis <firstname.lastname@example.org>,der Mouse
> <mouse@Rodents.Montreal.QC.CA>, email@example.com
> In-reply-to: <200001192039.VAA0000016530@zel459.zel.kfa-juelich.de>;
> fromM.Drochner@fz-juelich.de on Wed, Jan 19, 2000 at 09:39:37PM +0100
> X-Hi-To-All-My-Friends-In-Domestic-Surveillance: hi there, sports
> X-Mailer: Mutt 1.0.1i
> Delivered-to: firstname.lastname@example.org
> >> the problem as i understood it was that a packet with a unicast
> >> hardware address (not of my machine) but a broadcast ip address (no,
> >> not normal, but certainly manufacturable, and certainly matching me)
> >> will (a) be picked up by the card, (b) passed up to the upper layers
> >> and (c) responded to
A question for clarification: Is the above a correct statement?
Seems like what's discussed below doesn't relate to what's described
above. The above deals with a broadcast IP packet, which should
properly be handled by the IP stack. That it's delivered in a
unicast ethernet frame is weird, but at least promiscuous mode in
this case lets things happen correctly. Or am I missing something?
> >The driver must do the appropriate checks that (b) doesn't
> >happen. By checking some bit of the receive status if the
> >card is a more intelligent one, or by bcmp()ing the ethernet
> >header itself with conventional chips.
> >I'm not voting for removing this check (which is done correctly
> >in most drivers afais) - I'm just telling that the check
> >is not driver independant and therefore shouldn't be done
> >in ether_input().
> if the card can do it, that's fine. i just didn't expect the card to
> have knowledge of ip addressing. i just think that if some drivers do
> it and some don't, that's not a good thing. it means that your
> network behavior is network card/driver dependant. oxymoronic,
> basically it comes down to promiscuous mode, and the fact that it
> shouldn't alter a machine's behavior, except perhaps as a result of
> the additional packet processing.
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics |
Manager, CoreOS Networking | When crypto is outlawed,
Apple Computer, Inc. | Only outlaws will have crypto.
2 Infinite Loop |
Cupertino, CA 95014 |