Say hello to nDPI (Network DPI)
The equation “port = (application) protocol” no longer holds. DPI (Deep Packet Inspection) is the way to detect known protocols on non-known ports (e.g. http on ports other than 80) and traffic on know port that is not the one we expect (e.g. skype on port 80). On a nutshell, we need to look at packet content and see what’s inside. P2P protocols have been designed from day one with the ability to circumvent network policies in order to reach their peers, and they are good example of places where …