[Click] can someone please explain how click deals with IP headers?

[Daniel McBrearty]

Hi

Have been playing around with this great piece of software for a few
days. Had some success with it, but one thing seems to cause some
trouble.

I seem not to be understanding something basic about how many elements
handle IP headers.

For instance, if I have a config like this :

ipc IPClassifier( ip proto udp, - );
FromDevice( etho, PROMISC true ) -> ipc;
ipc[0] -> Queue() -> ToDevice( eth1 );
ipc[1] -> Discard();

Now, I run this in user mode, and send it a few hundred RTP packets.
It core dumps. The core dump goes if I remove ipc.

Other problems I have had have been trying to use SetIPAddress(
1.2.3.4, dst ) in such a config, but the ip appears unchanged in
wireshark.

Do these IP based elements expect the ethernet header to be stripped
off, or explicitly told the position relative to the start of an
ethernet header? I seem to remember seeing something like this when I
started reading the docs ... but I can't find that now.

thanks

Daniel