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From: Fabrice MARIE <fabrice@celestix.com>
Reply-To: fabrice@celestix.com
Organization: Celestix Networks
To: "Shipman, Jeffrey E" <jeshipm@sandia.gov>, "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: Re: TCP checksum?
Date: Fri, 14 Jun 2002 11:51:14 +0800
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Hello Jeffrey,

On Thursday 13 June 2002 23:10, Shipman, Jeffrey E wrote:
> I'm looking for a function similar to skb_checksum(), but
> for the tcphdr->check field. I'm playing around with a module
> I've written for netfilter and I would like to modify options of
> the IP and TCP headers. For example, right now I'm trying
> to set the destination IP to the source IP, but the TCP checksum
> is coming out incorrectly. How can I calculate this checksum?
> [...]

This functionallity is already provided by the ipt_MIRROR target.

If you want more info on netfilter module writting, read Rusty's
Netfilter Hacking HOWTO at :
http://www.netfilter.org/documentation/index.html#HOWTO
and if needed, post netfilter development questions on the
netfilter-devel mailing list, for more info :
http://www.netfilter.org/contact.html#devlist

Have a nice day,

Fabrice.
--
Fabrice MARIE
Senior R&D Engineer
Celestix Networks
http://www.celestix.com/

"Silly hacker, root is for administrators"
       -Unknown
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