RE: blocking ports

Use the network sniffer. Watch for every packet between your computer and
firewall. You will see the ports used.
 
Remarks:
 
First - I think it would be good to find out what you need to allow and
block all other ports, not trying to spy every kind of instant messenger to
find out the ports it is using in order to block them.
 
Second - there are messengers that use just port 80, the one your Internet
browser is using. Blocking that port will prevent your users from browsing
web pages as well. 
 
Best regards
 
David

-----Original Message-----
From: Angela Wawrzaszek [mailto:wawrzaszeka@AUSTEEL.com]
Sent: Wednesday, March 21, 2001 6:22 PM
To: Midrange Mail List (E-mail)
Subject: blocking ports


The instant messengers that come with many browsers like AOL create a
security problem.  We would like to block the use of instant messengers by
blocking the port through TCP/IP that they come in on.  Does anyone know how
to determine what port these messengers use?  Or any other way to prevent
use of these.   Monitoring that no one installs one on their PC would be a
nightmare,  and a full time job. 

Angie Wawrzaszek 
M.I.S. Department 

 

+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com.
| To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---