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Re: "Loopback" route through two cards?

To: kuznet@xxxxxxxxxxxxx
Subject: Re: "Loopback" route through two cards?
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Thu, 12 Sep 2002 21:59:10 -0700
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>, netdev@xxxxxxxxxxx, anton@xxxxxxxxx
Organization: Candela Technologies
References: <200209031254.QAA02008@sex.inr.ac.ru>
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.1b) Gecko/20020722
kuznet@xxxxxxxxxxxxx wrote:
Hello!


I know this is an FAQ, but I never saw an answer I liked.


And what kind of answers do you like? :-)


still impossible


It depends on sense which you put to "impossible".

There are two problems with this:

1. You cannot send to local address via any device but loopback.

The only way to override this is to use explicit SO_BINDTODEVICE
on sending socket. Hence, it is "impossible" not changing application.

Ooooh, this looks like what I'm looking for...


2. You cannot receive packets with local address from any device but loopback.

   This is impossible, but wthis time without not editing kernel,
   removing the check for local addresses in fib_validate_source().

Any clues to which part of this method needs to be changed? I see nothing obviously about checking for local IPs, but I'm sure it's in there somewhere!

Thanks,
Ben


Alexey



--
Ben Greear <greearb@xxxxxxxxxxxxxxx>       <Ben_Greear AT excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear



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