How do I let VNC control the main desktop like the mouse and keyboard in front of the computer?

Question

I'm on a Debian 8 machine now, and I'd like to set up VNC so that I can use my smartphone with a VNC client on it as a sort of a jury-rigged wireless mouse and keyboard.

This was the default (and I imagine only) behavior for VNC servers on Windows, but all the tutorials for Linux setup assume you want new X and window manager sessions for each client, whereas I want the same session as is being displayed on the main monitor.

How can I do this?

Answer 1

Assuming that you have vnc server already installed - it is pretty simple, just type this in the console of your running session, that you want to connect to:
x11vnc -display :0
That's all.