Write a pox program that receives the full packet data when no rule is matched (see https://github.com/noxrepo/pox/blob/carp/pox/misc/full_payload.py). Have it do something interesting based on what it can see in the full packet body, for example you could have the program record information about all HTTP get requests. For this to work you probably want every packet to go to the controller and then have the packet be forwarded without setting up a rule that would apply to other packets.
Write a pox program that receives the full packet data when no rule is matched (see https://github.com/noxrepo/pox/blob/carp/pox/misc/full_payload.py). Have it do something interesting based on what it can see in the full packet body, for example you could have the program record information about all HTTP get requests. For this to work you probably want every packet to go to the controller and then have the packet be forwarded without setting up a rule that would apply to other packets.