Re: about ip header options

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi Miguel,

On Wed, Nov 07, 2012 at 04:38:54PM -0600, Miguel Alejandro González wrote:
> Hello
> 
> I have a netfilter module on the mangle table PREROUTING... I want to
> validate unexpired routes in ipv4 headers, but I think the TCP/IP
> stack already does this... because it is mentioned on the rfc 1812 so
> I'm guessing it is already implemented by the kernel
> 
> but somehow my module catches the packet first before the kernel does
> its magic...
> 
> As I understand the picture I'm attaching represents the whole process
> the TCP/IP stack performs to handle the options in a IPv4 packet, but
> I still don't understand how netfilter works with the stack

This is rather old, but it helps to provide the big picture:

http://open-source.arkoon.net/kernel/kernel_net.png

> Do I have to process the packet's options in my module or what?

I think it's better if you try to explain what you're trying to do
with your new extension. That may help to attract people to help you.
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