Except… it sucks. It works for console-savvy users such as me, but, unsurprisingly, all my users (3 people) hate console windows. I know better than to force it upon them.
I would love to have a nice port knocker for Windows that would be windowed, have launchers, and be easily provisionable (i.e. I tell my user to paste some settings or import some file by double clicking it). To be honest, just not being console-based would be enough.
Edit: Please stop trying to convince me not to use port knocking. You're trying to solve a different problem than the problem port knocking solves. Whether port knocking is a good solution or not is irrelevant to this question.