Re: [uml-devel] [uml-user] Promiscuous mode interface bug?

[Paolo Giarrusso <blaisorblade@yahoo.it>]

Jeff Dike <jdike@addtoit.com> ha scritto: 

> On Thu, Aug 03, 2006 at 01:08:51PM -0700, Stephens, Allan wrote:
> > Where I think my confusion is arising is in the details of how
> the
> > filtering
> > controlled by the promiscuous setting is actually done.  If a
> packet
> > with 
> > the "wrong" destination address arrives at an interface, who
> checks to
> > see
> > whether the interface has been configured as promiscuous and
> > passes/discards it
> > accordingly?  I have naively assumed that this was handled in
> hardware
> > on the
> > NIC card in a real system, but is it really done by software?  

> Ah, a light goes on.  I believe that it is done on the card.

Yes, it is, you can set one (or even more, for special purposes) MAC
addresses to accept on a card or configure it as "no hardware
filtering done"; I've observed a network driver doing this, and I
think set_mac is the hook for this.

> > What I seem to
> > be
> > observing in my UML testing is that *nobody* is doing this
> filtering,
> > resulting in
> > unwanted packets being handed to my protocol (which sits directly
> on top
> > of the
> > Ethernet driver).  
> 
> And since UML doesn't have "cards", it may be that the driver
> should do the
> filtering at the bottom layer and it isn't.

I agree too; we may check however if the network stack implements
support for such "dumb" cards (probably by setting a flag) to avoid
coding it ourselves.

Chiacchiera con i tuoi amici in tempo reale! 
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