From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Beverley <andy@andybev.com>
Subject: Re: newbie question on netfilter-conntrack
Date: Sun, 20 Jun 2010 12:56:51 +0100
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To: Pete Kay <petedao@gmail.com>
Cc: netfilter@vger.kernel.org

Pete,

> I am trying to set up a rule such that any UDP packet coming from a
> specific IP:port will be redirected to another IP:port.  Could someone
> please give me an example how this can be done?

You'll need something like:

iptables -t nat -A PREROUTING -p udp --sport 1234 --source 1.2.3.4 \
	-j DNAT --to-destination 4.3.2.1:4321

If you do 'man iptables' you will see details of all these options. You
may also find that this simple kernel routing diagram helps:

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

> Also, I would like to know if it is possible to monitor the proxying
> of the UDP packet to obtain information such as jitter and packet
> lost.  How can I do that?

Not sure about that I'm afraid; maybe somebody else can help.

Andy