Firewall : ports for TCP and UDP Connections

Daniel Chung-Chi Chuang (
Mon, 24 Mar 1997 18:09:30 +0000


When I run cu-seeme application for the point to point connection,
I make the trace for all traffic between these two end stations.
I found out there are two kind of connections : one is the tcp
connection from port 7649 to port 7648; another is udp connection
from port 7648 to 7648.

I have the following questions,

1. What are the main functions for the tcp connection ? Is it
true that cu-seeme will set up tcp connection when you call
another site ? Is it used as the control session ?

2. What are the main functions for the udp connection ? Is it
used for the video transfer on the video window ?

3. What are the dependency of these two channels ( tcp and udp )
? Will the udp channel depend on the tcp channel ? or Will
the tcp channel depend on the udp channel? Which one should
be started first ?

4. Are there any documentations giving out the detailed operation
sequencing or technical information about cu-seeme application?

5. Any suggestions of firewall rule for cu-seeme application.

Best Regards,

Daniel Chuang