[Click] Please Help! What am I doing wrong?

[Tushar Soni]

Hi,

This is my second mail to the mailing list. I hope there is someone who can help me out with this. 
I am running the following script at one of my stations (station_1):

tun::KernelTun(1.0.0.1/8);
FromDevice(ath0, SNIFFER false)->Strip(14)->CheckIPHeader()->MarkIPHeader(0)->IPClassifier(dst udp port 1234)->tun;
tun->Discard;

Now at this station_1 when I run this script and I run VLC to listen to a unicast udp stream (which was sent by another station_2 to the ip address of station_1=192.168.5.7) the video works and the packets pass through click like i want them to.

When I ask station_2 to stream to a multicast address say 224.224.224.224  and i ask the vlc at station_1 to join this multicast address (without running click) it plays video. But when i run the above script in click along with vlc the video does not play anymore. What am I doing wrong???
I tried IPPrint() after IPClassifier in line 2 and it is printing the ip packets with srcadd:192.168.5.1(station_2) and destaddr:224.224.224.224. Which means that the multicast packets are not being dropped anywhere.

I also did "tcpdump -i tun0" which showed me all the packets. Does this mean that there is no problem with click and the problem lies elsewhere (maybe the kernel)??? But why would it work for unicast and not for multicast??? Or is my entire idea of using KernelTun for passing packets through click wrong??

My only motive is to create just a simple scenario of A to B connection, where A streams a video and B plays the video, but the packets should pass through click (preferably using user level) so that I can modify just the contents of the packet in certain ways. I would build other things on top of it but that would be only if i can run this simple scenario.

I have banged my head on the wall for some time now, so any kind of help or pointer would be greatly appreciated.

Thanks

Tushar