Create Firewall

In this exercise, you'll modify your switch to reject connection attempts to specific ports, just like a firewall.

This exercise is meant to show how OpenFlow can even do basic layer-4 tasks. Other uses could even extend into layer 7; cookie-based load balancing, for example.

Testing your Firewall

To run iperf on xterms, on the xterm for h2, start up a server:

 $ iperf -s

Then on the xterm for h3 start up a client:

 $ iperf -c 10.0.0.2

Your task is to prevent this from happening, and to block all flow entries with this particular port.

You can change the port used by iperf with the -p option. Both server and client will need this option specified. Again, NOX core.py will be useful for figuring out how to specify a flow entry that matches on wildcard ports. Also note that an empty action list will drop a packet; there's no explicit drop action.