Re: [RFC] ip / ifconfig redesign

[Marc Singer <elf@buici.com>]

On Mon, Dec 05, 2005 at 06:59:07PM +0100, Jeroen Massar wrote:
> Marc Singer wrote:
> > On Mon, Dec 05, 2005 at 09:01:00AM -0500, John W. Linville wrote:
> >> On Sat, Dec 03, 2005 at 10:33:32AM -0800, Ben Greear wrote:
> <SNIP>
> >> The association between IP addresses and links is already a bit murky.
> >> Reference the arp_announce sysctl for what I mean.  I recall Dave M.
> >> emphasizing on at least one occassion that IP addresses belong to
> >> the _box_, not to the link.
> >
> > Precisely the case.  It should be the case that a box response to an
> > arp on *any* interface for *any* IP address known to the box.
> 
> Thus you have the following nice setup:
> 
> 10.100.10.0/24 = 10Gbit streaming network
> 10.100.20.0/24 = 10mbit admin network
> 
> 10.100.10.1 on eth0
> 10.100.20.1 on eth2
> 
> Then some idiot misconfigures his client box, putting 10.100.10.42/24 on
> the NIC that is supposed to be in the admin network only.
> Suddenly your 10mbit link is full because the arp's get answered on this
> link.

Huh?  The arp requests don't establish routing and they aren't a
significant source of traffic.  Besides, all I suggested is that if a
machine receives an arp request on eth2 for an address it has on
10.100.10/24, it should answer with it's MAC address on eth2.  

My readings of the RFC do not address this issue directly.  My
understand of this behaviour is from a discussion with someone
regarding iptables.

Moreover, if you allow users to willy-nilly connect to your networks,
you've got a completely different kind of problem on your hands.