Is it a firewall or a proxy server? Those are two different
problems, one of which is solved more-or-less completely
and one of which is solved in a sort of half-fast way.
If the machine between you and your VNC server is a packet-filter
firewall that only allows connections to particular ports, but does not
otherwise interfere with the data stream, then you're probably
OK. If there's a way to control the RFB port setting separately from
the HTTP port in the Java applet, you could do exactly as you suggest
in your message (set the server to listen on port 80 for HTTP
and port 21 for RFB or whatever). I don't know of a way to
do that in the Java viewer, but I expect it would be easy to
add such a feature. And of course if you use the native
VNC viewer for your platform you only need to be able to
connect to the RFB port, so you just need to make your VNC server
listen for RFB connections on a port that gets through the
firewall. Finally, if you *must* use the Java viewer for some
reason, the patches available at
http://home.earthlink.net/~jknapka/vncpatch.html
might help you; they allow you to create a server that delivers
the Java applet over the RFB port, so you need only one
port to be accessible. In any case, the trick is figuring out
what display number to tell your viewer to connect to.
Typically it will be a very large value, something like
2^32-(5900-<desired port number>).
If the machine between you and your VNC server is a proxy server,
then you're in trouble. Proxy servers expect clients to interact
with them using some proxy-specific protocol, so the client
would need to know about that protocol.
I believe there are patches available on
http://www.uk.research.att.com/vnc to make some subset of the
VNC viewers connect through a SOCKS proxy. But there's no
general solution at present.
Alternatively, you can use one of the existing HTTP tunneling
services to create a TCP/IP connection encapsulated within
an HTTP data stream. For example, httptunnel does this:
http://www.nocrew.org/software/httptunnel.html
However, this solution will be rather slow, and you will be
dependent on an external tunnelling server to maintain
your connection.
HTH,
-- Joe
Nathan Shaw wrote:
>
> Was there ever a conclusion to whether or not you could connect to a VNC
> server through a Proxy server if they only allow communication through Port 21
> and 80 (for example) ?
>
> I was thinking you could set the Java Viewer to listen on port 21, and then
> the RFB to run on port 80. This way you could get through to your server even
> though there may be a firewall/proxy setup.
>
> The only thing is.. how in the world do you change the port that the Java
> Viewer listens/downloads on? I know the RFB port is display + 5900 but
> where/how can I specify the port for the Java Viewer?
>
> Has anyone successfully done this? Any help is greatly appreciated!
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-- Joe Knapka
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