From mboxrd@z Thu Jan  1 00:00:00 1970
From: Leonardo Balliache <leoball@opalsoft.net>
Date: Sun, 20 Jul 2003 15:19:54 +0000
Subject: Re: [LARTC] OUTPUT chain marking after or before routing?
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To: lartc@vger.kernel.org

Hi,

At 08:04 a.m. 18/07/03 +0300, you wrote:

>----- Original Message -----
>From: "Martin A. Brown" <mabrown-lartc@securepipe.com>
>To: "Chijioke Kalu" <kchijioke@msn.com>
>Cc: <catalin@electricant.ambra.ro>; <lartc@mailman.ds9a.nl>
>Sent: Thursday, July 17, 2003 6:55 PM
>Subject: Re: [LARTC] OUTPUT chain marking after or before routing?
>
>
> > Catalin,
> >
> > >When I try to connect to a smtp port somewhere in the Internet, tcpdump
>show
> > >me that these packets go to the eth2 interface (the main table default
> > >route). I don't know where is my mistake but it seems that the marking=
 in
> > >the OUTPUT chain occurs AFTER and not BEFORE routing. Is this a correct
> > >behaviour? How can I solve my problem? Please help!
> >
> > According to my reading of the KPTD (and my understanding), packets
> > generated on the local machine have already been routed by the time the
> > OUTPUT chain is traversed.  See:
> >
> >   http://www.docum.org/stef.coene/qos/kptd/
> >
>
>I'm very confused now. Look what is written in the iptables man page:
>
>#############
>  mangle This  table  is used for specialized packet alteration.  It has t=
wo
>built-in
>               chains: PREROUTING (for altering incoming packets before
>routing) and OUTPUT
>               (for altering locally-generated packets before routing).
>######################
>
>So how it is? OUTPUT marks packets AFTER or BEFORE routing?

Just before "output routing". OUTPUT is for locally generated packets.=20
These packets are also to be routed (output routing). OUTPUT mangle marks=20
"locally generated" packets just before they are "output routing".

Perhaps confussion is because also input routing exists where a decision is=
=20
taken: is this packet for this host or it has just to be forwarded? Read=20
Stef=B4s remarks on the diagram:

Output routing : the local process selects a source address and a route.=20
This route is attached to the packet and used later.

Best regards,

Leonardo Balliache

Practical QoS
http://opalsoft.net/qos


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