[Tutor] How to monitor streaming data from the internet via modem?

[Alan Gauld]

> If the trading program is in java or perl, can I just tap into the raw 
> data that trading program is recieving through the modem without 
> interfering with the trading program's own information stream?

Assuming it turns into IP data at some satage then you can get several 
programs - some are even free! - that will sniff IP packets and either 
log them to a file or display them on a screen. This can run in 
background with only slight impact on performance. So you can 
use Popen to capture the output and analyze it.

Search for 'packet sniffer' on Google. Ethereal is one well known 
and powerful one, but there are others which may be simpler to 
use. Here is one web site that lists a few:

http://netsecurity.about.com/cs/hackertools/a/aafreepacsniff.htm

Alan G
Author of the learn to program web tutor
http://www.freenetpages.co.uk/hp/alan.gauld