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Re: Woody routing question...

On Fri, Aug 09, 2002 at 11:00:21PM +0200, Marc Haber wrote:
> On Fri, 9 Aug 2002 10:19:36 -0700, Ted Deppner <ted@psyber.com> wrote:
> >If you want to be able to use both IPs from either network (a common
> >occurance even if you didn't plan it), you should probably turn off
> >RP_FILTER in the kernel.
> Why?

rp_filter will drop packets coming in interface A that have a source in
the network of interface B.  It essentially polices that packets that
"should" come in B have to come in B.  In a well connected mesh, it's
possible to have network B devices route packets through to interface A
(interface B's cable unplugged, route to B becomes available through A;
arp behavior in two NIC networks on the same switch can exhibit this
behavior sometimes as well).

This is only usually a concern where you have two interfaces facing the
same general network traffic.

> use tcpdump -e to actually see the MAC addresses where the packets are
> sent to.

Good point!

Ted Deppner

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