Examining and modifying packets in userspace using Netfilter
I wanted to know how I could look at IP packets (including header and payload) arriving at a Linux Box by redirecting them to a users level process.
I plan to modify the TCP and IP headers in the process before sending them on the wire again.
This is just an academic excercise and not a system admin problem.
I am looking for a solution with minimal amount of kernel programming or firewall configuration.
I have looked at Netfilter documents but none of them have specified an exact method telling me what to do.