Filtering UDP packets from going up the stack

I would like to be able to filter UDP packets from entering my Linux
stack. It's an experiment I'm working on. If anyone knows off the top
of their head how to do this I would appreciate the input. First off, I
know it probably requires rebuilding the kernel. Secondly, based on my
review of the Linux network stack source code it appears that I can
easily determine which packets are UDP but the thing that concerns me is
that it appears I need to free some dynamically created packet buffer
even though I want to throw away the packet. Anyone have any
suggestions or things to look out for?

Steve Helding wrote:
> I would like to be able to filter UDP packets from entering my Linux
> stack. It's an experiment I'm working on. If anyone knows off the top
> of their head how to do this I would appreciate the input. First off, I
> know it probably requires rebuilding the kernel. Secondly, based on my
> review of the Linux network stack source code it appears that I can
> easily determine which packets are UDP but the thing that concerns me is
> that it appears I need to free some dynamically created packet buffer
> even though I want to throw away the packet. Anyone have any
> suggestions or things to look out for?
>

Probably 'iptables' with 'QUEUE' and an application for using that
can help.
You don't have to rebuild the kernel then.

Toni