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Date: Mon, 17 Jan 2005 15:22:46 +0100
From: Julien Lesaint <julien+fbnet@titoon.net>
To: Chuck Swiger <cswiger@mac.com>
Message-ID: <20050117142246.GA18374@titoon.net>
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cc: freebsd-net@freebsd.org
Subject: Re: ttl-exceeded sourced by arrival interface ?
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On Sat, Jan 15, 2005 at 09:46:54PM -0500, Chuck Swiger wrote:
> Julien Lesaint wrote:
> >Quick reminder: in the case the route to the packet's source is not the
> >interface this packet arrived on, do we have a way to source ICMP errors
> >(ttl-exceeded) with the original interface's IP address ?
> 
> Yes.  Use IPFW's fwd mechanism, or even set a host route for the source IP 
> address pointing to whichever interface you please.

I don't understand how this forward feature could help... Anyway I'm not
using IPFW. Adding a route for each source IP is definitely not feasible.
Maybe I wasn't clear enough so I repeat: I just want the FreeBSD box to
send ICMP errors with the IP address of the interface the packet which
generated this error, arrived on. Just like real routers... The "problem"
only occurs in an assymetric routing context, i.e. the router which is
generating the ICMP packet will not reply via the interface the original
packet arrived on.

> That's what the routing table is supposed to do, yes.

This is the normal behavior in all situations but this one, yes...

-- 
Julien Lesaint.