libipq and QUEUE

libipq and QUEUE

[Jørn Andre Berntzen]

Hi

I'm trying to write a redirect code that will change the destination 
address
on specific packets using libipq and trying to avoid coding a 
kernel-module.
 From reading the man page on libipq and the functions one should be able
to manipulate the packet, update the checksum and reinject the packet to 
kernel.

Has anyone here done this successfully or am I on the wrong path?
Is it possible to change the destination address using the ipq library and
the QUEUE target or does one have to make a module for doing this?

Any help is greatly appreciated.

Regards,
Jørn Andre

Re: libipq and QUEUE

[Maarten Wijnants]

Hi Jorn,

It IS possible to change the destination address of a packet in userspace 
using libipq and the QUEUE target. However, if you do this, it is my 
experience NO rerouting will occur. For example, if you change a packet's 
destination from X to Y using libipq and subsequently reinsert the packet in 
the kernel, the packet will still be delivered to machine X, although the 
header of the packet will specify it is destined for machine Y! If you want 
rerouting to occur, I think you are better off with the NAT table (I myself 
have no experience with this).

greetings,
Maarten

----- Original Message ----- 
From: "Jørn Andre Berntzen" <jornandr@stud.ntnu.no>
To: "Netfilter Development Mailinglist" 
<netfilter-devel@lists.netfilter.org>
Sent: Thursday, March 31, 2005 9:05 AM
Subject: libipq and QUEUE


Hi

I'm trying to write a redirect code that will change the destination
address
on specific packets using libipq and trying to avoid coding a
kernel-module.
 From reading the man page on libipq and the functions one should be able
to manipulate the packet, update the checksum and reinject the packet to
kernel.

Has anyone here done this successfully or am I on the wrong path?
Is it possible to change the destination address using the ipq library and
the QUEUE target or does one have to make a module for doing this?

Any help is greatly appreciated.

Regards,
Jørn Andre