Networking Stack Options with a DE2 Board

How can one impliment a network stack on a DE2 Board with Quartus 6.1 Web, NIOS II IDE 6.1 Evaluation?

I need to be able to send/receive network packets for a research application in parallel processing. If possible, I would like to receive the packets in a permiscious mode (e.g. like a sniffer).

Please list all options, including those that are paid/licensed (e.g. uC/OS-II, uCLinux, etc).