Re: Firewall : ports for TCP and UDP Connections

Bill Woodland (
Tue, 25 Mar 1997 20:32:17 -0600

At 06:09 PM 3/24/97 +0000, you wrote:
> When I run cu-seeme application for the point to point connection,=20
>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.=20
> 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 ?

As far as I know, the only TCP that the CU client does is the
gethostbyname() function (Steve Edgar or Brian O'Shea correct me if I'm
wrong). The client does everything else via UDP on port 7648.
>2. What are the main functions for the udp connection ? Is it
> used for the video transfer on the video window ?

UDP is used for, audio, and video.

>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 ?

The CU client will handle all of this for you. See answer to number 1.

>4. Are there any documentations giving out the detailed operation=20
> sequencing or technical information about cu-seeme application?

Not as far as I know of. Cornell has some techie stuff in the works, but I
don't believe it's available yet.

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

Open up UDP ports 7640 thru 7648

>Best Regards,
> Daniel Chuang
Bill Woodland (Squeek =A9)
Email, PowWow, and ICQ:
CU-seeME Unsubscribe? Go to