Question about commercial use and the GPL

Stephan A. Edelman stephan "at"
Tue Apr 13 18:59:01 2004

We have a similar solution that we use to support our own customers, based
in part on VNC.

We've essentially packaged the vncserver into a single signed 390KB
executable (not an installer) that initiates an outgoing support connection
across the Internet to an available station in our help desk. The station is
running the vncviewer in listen mode.

The beauty of this setup is that most routers (at the customer's end) will
permit outgoing connections to be initiated so in general we have no problem
providing support to our customers.

Here are some screen shots for those interested in how it's done.



----- Original Message ----- 
From: "Justin Patterson" <justinp "at">
To: <vnc-list "at">
Sent: Tuesday, April 13, 2004 9:47 AM
Subject: Question about commercial use and the GPL

> Hello,
> I'm interested in using RealVNC as part of a bigger (commercial) support
> solution and there are a few modifications that I need to make:
> 1) I want to be able to have the server shutdown if there's no viewer
> connected within a certain timeout period.  This is for a one-time
> support-type application, so I don't want to leave the viewer running if
> there's a disconnect between the supporter and the supported somehow.
> 2) I don't want to make any changes to the server's registry or
> That's because I don't want to interfere with an existing VNC server that
> may already be installed (and running) on the machine.  For this, I was
> thinking about making it so that it only takes command line arguments to
> configure it (and getting rid of the properties dialog).
> I've prototyped some of these changes and they seem to work for what I
> So, my question refers to the part of the GPL which states that a "work
> based on the Program" must be licensed under the GPL.  In my case, I don't
> mind releasing my modified source for the RealVNC server.  I can
> that back to the project if you guys are interested.  Otherwise, I can
> my modified RealVNC source to my customers.
> I am, however, not interested in releasing the source of the web
> (ActiveX controls, Java servlets, etc.) that control the launching of the
> server and viewer.  This application does a lot more than just launch VNC
> (that's just one aspect of the support relationship), so it's hard for me
> see is as a "work based on the Program."
> Can someone please clarify exactly how much of my code has to be licensed
> under the GPL to be able to use RealVNC?  Is it just the source code for
> RealVNC binaries?
> Thanks for your help,
> -Justin
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