basic stamp network analyser?

[dylan <dylan@iici.no-ip.org>]

hi --

in the wee hours of the night (when one is normally sleeping...) i was
tinkering around with a BS2 module (basic stamp 2) and how it can interact
with a PC via the serial bus....

Here is my question - is it possible for a shell script / perl script to
monitor a filtered data stream from 'tcpdump' -- looking for key pieces of
text. when there is a match on say "FTP"  or "WWW" or "SSH", the shell
script or perl script would output a single byte of data to the serial port:

for example:

$tcpdump | grep -v stuff_to_filter | some_perl_or_shell_script > /dev/ttyS0

so for every packet with a header that matches

SSH   --> output a '1'
WWW   --> output a '2'
FTP   --> output a '3'   .... and so on.

the basic stamp would be listening for data on the serial port, in single
byte chunks from 1 - 9 (or a - z, or whatever). based on the byte it
receives it would set a corresponding I/O pin high, short pause, then low.
the I/O pins would be connected to LEDs -- which would yield a crude display
what what kind of traffic exists on the network -> by blinking various LEDs.

is it possible to search streams of data like this, and would such a search
actually provide reliable information?

any ideas?

thanks,

dylan