Re: BUG: 2 NICs on same network

From: Roland Kuhn (rkuhn@e18.physik.tu-muenchen.de)
Date: Thu Apr 25 2002 - 07:09:08 EST


Hi!

On Tue, 23 Apr 2002, Frank Louwers wrote:

> Hi,
>
> We recently stummed across a rather annoying bug when 2 nics are on
> the same network.
>
> Our situation is this: we have a server with 2 nics, each with a
> different IP on the same network, connected to the same switch. Let's
> assume eth0 has ip 1.2.3.1 and eth1 has 1.2.3.2, with a both with a
> netmask of 255.255.255.0.
>
> Now the strange thing is that traffic for 1.2.3.2 arrives at eth0 no
> matter what!
>
This is in perfect agreement with rfc1122, section 3.3.4.2. Linux uses the
weak ES model, so the interface doesn't matter. There was once a patch
floating around for 2.4.6 that made the kernel accept only arp coming from
the 'right' interface. arp_self_only, or something. I have attached it,
but I have no idea if it still applies/works.

Ciao,
                                        Roland

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