I now want to implement a packet which is QoS based(with bandwidth reserved), I will look at the destination of the sending packet and check its flow-label, then forward the packets according to the information I just mention above.

Now, I can pass the packet to the userspace by making use of the IPtables (- j QUEUE ), and I have written a usespace program to check the destination of the received packet and changed it accordingly. I can see it works as it can display on the screen.

My problem is that how I can keep forwarding this packet with destination changed to other pc/router machine or even pass back to the sender.

Thanks!!!!!!