Having been tinkering around with some LEDs (changing the LEDs in my 
router and computer), earlier today I had an idea.

My m0n0wall machine is in the attic. I'm wondering if somehow I can 
attach a custom-built device to the serial port and run a cable down 
here (from serial port to device) for various purposes.

The device would just consist of a few LEDs, mainly for the "pretty 
lights" effect.

What I'd be interested in doing is ultimately developing a small 
PIC-based system where m0n0wall sends out various information to the 
serial port. This information instructs which LED is to turn on/off.

I thought of having an LED that goes on for a few milliseconds whenever 
something is blocked by the firewall, and maybe another for when a 
connection is made which is accepted. And maybe another for rejected 
connections.

After that, maybe a few more to indicate activity on certain ports 
(http, imap, ftp) along with ranges (bittorrent / edonkey port ranges as 
one LED)

I'm wondering how I'd go about adding such a thing to m0n0wall. I'd have 
to code it myself, I understand that. But how???

And how would my program get notified that a connection had been made / 
data is flowing on a certain port?

I also considered just using a network-based thing for this, but it's 
not really valuable traffic and although its small, it might lag out a 
bit as packets are bundled.

Strange questions, I know. But I want to make a gadget :)