Command line version of connecting to listening viewer doesn't work
geza at pumi.org
Sun Feb 28 23:38:14 GMT 2010
I am getting an error message "Unable to locate existing VNC Server". I
tried it with :5500, ::5500 and without any port designation. I am doing
these tests on my home network with two computers, both of them have XP Pro
BUT THE MOST IMPORTANT FACT IS THAT THERE IS NO PROBLEM CONNECTING TO THE
LISTENING VIEWER COMPUTER BY RIGHT CLICKING ON THE VNC SERVER ICON IN THE
SYSTEM TRAY AND ADDING THE IP ADDRESS TO THE DIALOG WINDOW "Connect to
listening VNC Viewer".
I also tried to connect to the listening computer using telnet, the
connection was successful.
So, the bottom line is, that using the GUI interface there is no problem at
all, using the command line interface it gives the error message "Unable to
locate existing VNC Server".
"C:\Program Files\RealVNC\VNC4\winvnc4.exe" -connect computer2
I think either I am not using the correct syntax or RealVNC has a
programming error or bug in it and it cannot interpret its own command line
What is interesting is that I did a Google search on this problem, and I
found numerous postings about the same problem with RealVNC, but not one had
a solution to this problem.
About your cmd utility: did I understand it correctly that you supposed to
run it on the server end, so that if the connection gets lost, it will be
restored from the server end without human interaction? Will that work on
Windows Vista and Windows 7 if you get bumped out by the UAC?
Sent: Friday, February 26, 2010 5:45 AM
Subject: RE: Command line version of connecting to listening viewer doesn't
To debug a thing like this, run it in a command window, so you can see any
I believe the problem may be with the trailing :5500 - I've never needed to
specify this at the server end, only to set up port-forwarding on the
firewall at the receiving (client) end. Take that off and it should work.
You may be interested in a command script I've developed to keep checking
for an established connection and re-connect if it has dropped (something I
developed when trying to manage a system in Ghana from my location in
London). You can find it here:
Behalf Of Geza Levai
Sent: 25 February 2010 23:01
Subject: Command line version of connecting to listening viewer doesn't work
I am trying to create an icon for connecting to a listening viewer with the
information that I gathered about this subject, but it doesn't work.
All I can see, that a black DOS command line window pops up for a
millisecond in the left upper corner of the screen, but nothing else
The same computer has no problem connecting to the listening viewer by
having the user typing (copy/pasting) the IP address of the viewer in the
(The port 5500 on the firewall of the listening viewer is forwarded to the
listening computer (otherwise the manual method wouldn't work either,
This is the command line that I think should work, but it doesn't: (IP
address here is a bogus one, of course)
"C:\Program Files\RealVNC\VNC4\winvnc4.exe" -connect 99.999.999.99:5500
Any idea why this command line doesn't work but manually the PC can connect
to the listening viewer without any problem?
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