This directory contains third-party software that may be useful for debugging.
The "ofp-tcpdump.patch" patch adds the ability to parse OpenFlow messages to tcpdump. These instructions assume that tcpdump 4.3.0 is going to be used, but it should work with other versions that are not substantially different. To begin, download tcpdump and apply the patch:
wget http://www.tcpdump.org/release/tcpdump-4.3.0.tar.gz tar xzf tcpdump-4.3.0.tar.gz ln -s tcpdump-4.3.0 tcpdump patch -p0 < ofp-tcpdump.patch
Then build the new version of tcpdump:
cd tcpdump ./configure make
Clearly, tcpdump can only parse unencrypted packets, so you will need to connect the controller and datapath using plain TCP. To look at the traffic, tcpdump will be started in a manner similar to the following:
sudo ./tcpdump -s0 -i eth0 port 6653
The "-s0" flag indicates that tcpdump should capture the entire packet. If the OpenFlow message is not received in its entirety, "[|openflow]" will be printed instead of the OpenFlow message contents.
The verbosity of the output may be increased by adding additional "-v" flags. If "-vvv" is used, the raw OpenFlow data is also printed in hex and ASCII.