From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Beverley <andy@andybev.com>
Subject: Re: how the packet is traversed
Date: Tue, 02 Oct 2012 21:54:39 +0100
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To: Giuseppe Longo <giuseppelng@gmail.com>
Cc: netfilter@vger.kernel.org

On Tue, 2012-10-02 at 22:20 +0200, Giuseppe Longo wrote:
> Hello,
> i'm a student of computer science, working on a project using iptables.
> I'm confused how the packet is treated when it's arrived in the iptables.
> 
> Someone can explain me this process?

Well there are various tutorials, none of which I can find right now,
but a picture paints a thousand words...

This diagram is a good place to start as it's simple, although probably
out of date:

http://www.docum.org/docum.org/kptd/

Once you've got your head around that, this is the fully comprehensive
one, but tougher for beginners:

http://upload.wikimedia.org/wikipedia/commons/3/37/Netfilter-packet-flow.svg

If you've got any specific questions, then please ask!

Andy