Take a look at bettercap a, surprisingly feature complete, open source MITM (man in the middle) framework. This project appeared on the trending Ruby repositories over on Github, which I generally keep a pretty close eye on.
While I am certainly not advocating using it for unscrupulous actives, it does highlight the necessity of securing your networks both at home and professionally. Bettercap has an extremely easy to use CLI. I fully support these kinds of projects as they help push the need for security and bring methods of attack out of the shadows. Information is power.
I took it for a spin on my home network (that is properly secured of course), and it was incredibly easy to use. Even someone who is just a bit technical could get the hang of using it.
Secure your networks folks, the number of tools available for subterfuge continues to grow!