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Date: Thu, 16 Nov 2000 18:18:40 +0100
From: Andi Kleen <ak@suse.de>
To: Nishant Rao <nishant@cs.utexas.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Setting IP Options in the IP-Header
Message-ID: <20001116181840.A18222@gruyere.muc.suse.de>
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In-Reply-To: <Pine.LNX.4.21.0011161111210.5572-100000@crom.cs.utexas.edu>; from nishant@cs.utexas.edu on Thu, Nov 16, 2000 at 11:11:45AM -0600
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On Thu, Nov 16, 2000 at 11:11:45AM -0600, Nishant Rao wrote:
> Hi,
> 
> We are conducting some research that involves setting our custom data as
> a new IP option in the IP header (in the options field) of every packet.
> 
> We have poured over the source code but it is quite confusing to figure
> out how the details of the way the options field is split among various
> options (ie. offsets etc). Can anyone help us figure out how to add new
> custom options into the IP header ? 

man ip(7), see the IP_OPTIONS socket option.

Linux only echoes received options, but never sets them by default unless that 
socket option is specified. So it depends on the application and/or the sender.

-Andi
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