TridiaVNC Pro and GPL: Re: Tridia VNC

W. Brian Blevins brian.blevins "at"
Fri, 08 Mar 2002 14:03:48 +0000


I am most definitely not a lawyer.

> According to :
>   Is TridiaVNC Pro open source software?
>   No. Although the TridiaVNC components are all open source and
>   licensed under the GPL, the TridiaVNC Pro components are closed
>   source. While commercial or closed source software may not link with
>   the open source software, there is no restriction from bundling and
>   shipping open source software in a commercial product. Many hardware
>   manufacturers include open source software with their own closed
>   source program packages.
> Personally, I suspect there is a GPL violation going on here.  In fact,

We respectfully disagree.  In fact, others posting to this forum
in the past would appear to disagree as well:

> I'm fairly certain of it.  TridiaVNC (or at least components of it) are
> distributed as a part of TridiaVNC Pro.  It even installs a TridiaVNC
> subdirectory which includes a copy of the GPL.  However, the GPL reads:
>   0. This License applies to any program or other work which contains a
>   notice placed by the copyright holder saying it may be distributed
>   under the terms of this General Public License.  The "Program", below,
>   refers to any such program or work, and a "work based on the Program"
>   means either the Program or any derivative work under copyright law:
>   that is to say, a work containing the Program or a portion of it,
>   either verbatim or with modifications and/or translated into another
>   language.

What precisely does the GPL define as a "derivative work"?

Basically, the closed source components in TridiaVNC Pro do not link
with the open source components.

> TridiaVNC Pro looks like a derivative work to me.  Even if they could
> somehow prove in court that it is not a derivative work, there is a
> problem with the click-through license in the TridiaVNC Pro installer.
> It removes many of the freedoms granted by the GPL for the entire piece
> of software without any exclusions for the open source components.

The viral effect of the GPL requires linkage.  Without linkage, the
open source freedoms do not extend to other binaries bundled with the

The freedom in the VNC/TridiaVNC/TightVNC code is based on free access
to the source code.  This is available 24x7 from our anonymous CVS server

> - -- 
> Mike Ossmann, Tarantella/UNIX Engineer/Instructor
> Alternative Technology, Inc.


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