We've had a lot of fun poking around the network in the first few chapters. There has been an emphasis on man-in-the-middle attacks, and it's easy to see why: they're particularly devastating when performed properly. However, your focus when educating your clients should be the fact that these are fairly old attacks, and yet, they still often work.
One reason is the fact that we still rely on very old technology in our networks, and man-in-the-middle attacks generally exploit inherent design vulnerabilities at the protocol level. Consider the internet protocol suite, underlying the internet as we know it today: the original research that ultimately led to TCP/IP dates back to the 1960s, with official activation and adoption gaining traction in the early 1980s. Old doesn't necessarily imply insecure, but the issue here...
