Wondering if there's freeware

that detects when your system is under remote control over a network. Maybe a taskbar warning light or some such.

Anybody know of such a thing?

Check sourceforge for some nice freeware.

Probably a way around it, but the system's management panel usually tells if there any files being used or shared from an outside source.

I don't necessarily want it blocked. Just want to yank chains when some buddies are watching.