Re: Entirely ignoring TCP and UDP checksum in kernel level

Brad Campbell
2004-08-22T06:01:24Z

Josan Kadett wrote:
> Well, the device fails only in one type of operation, that is when it has to
> receive packets from an internal port, it sends packets via its external IP
> address.
>
> I have managed to disable IP header checksumming by hacking the kernel (in
> file ip_input.c). Now I have to do the same for tcp_input.c and udp.c .
> Packet mangling will not be required because when I turn the rp_filter off,
> the kernel does not care whether it is coming from the intended source or
> not.
>

Just a completely random thought. What about re-calculating the checksum and correcting it when the
packet hits the IP layer prior to it being passed out to the relevant protocol handlers?

Regards,
Brad