[aprssig] "Controlling" things with APRS

[Stephen - K1LNX]

Hopefully I can explain this well enough to where it makes sense, so 
here goes...

I have a KPC-3+ in digi mode and I have been looking at the telemetry 
options as well as the control outputs available. I have seen the "CTRL" 
option in the KPC-3 manual, but I would like to take this further. I 
would like the ability to send a specially crafted APRS packet/message 
to my TNC and have the "CTRL" on or off accordingly. Security is the 
first thing that comes to mind as anyone watching the on-air activity 
could easily duplicate the packet as well. There's always the remote 
control option as well, but I like the idea of sending a single packet 
that I could pre-program in an HT for example to simply switch something 
on or off.

My intent of this usage is that I have a repeater with GPIO pins that I 
can toggle to do various things, one of them being disabling the 
repeater, or changing the channel wtc. I don't know that the KPC-3+ is 
capable of doing this? Can it receive a packet and say, act on it 
accordingly?

Is anyone actively doing what I describe above, or am I trying to 
re-invent the wheel? In summation, I would love the ability to send a 
single APRS packet to my TNC and have it switch something "on" or "off" 
(high or low respectively)

73 and thanks for any insight,
Stephen
K1LNX