Packet Filter to redirect a packet to a user level process

akawale · 03-23-2005, 01:38 AM

Hi,

I wanted some information on how to redirect packets arriving at a linux box to a user level process running on that machine.

I would appericiate a solution with a minimal amount of kernel module programming and/or firewall configuration.

My intention is to modify the packet and send it to it another destination.

Thanks.

- Akshay

scuzzman · 03-23-2005, 02:09 AM

Do you seek to send the packets to a specific port? If so, the information is very attainable. Look at http://www.linuxguruz.com for great IPTABLES tutorials. You seek "port forwarding".

akawale · 03-23-2005, 05:18 AM

No, I need access to the entire IP header and payload... Thanks for the link though I'll definately check it out.
Does anybody have any specific ideas?

Thanks.

- Akshay

amitsharma_26 · 09-01-2006, 01:06 PM

You have to use natting in this case. Rewritting the packet with SNAT/DNAT can make you do a lot with your packets. You can also forward the packets over to different ports as well.

The only basic rule that fits in this case; is to understand the basics (for natting); Make sure that your packet should always have a same class Source-ip & destination ip if incase you are not acting as a gateway for your clients.

Above all natting in not at all difficult & you can get the know how of them i think in a few days as well.