Knowledge base

Knowledge base: All Platforms
Starting Listening VNC Viewer and establishing a reverse connection

You can establish a reverse connection to a Listening VNC Viewer, allowing the Viewer user to bypass the authentication scheme and control the Server User's computer. When a connection is made in this way, VNC Viewer does not connect to VNC Server, but instead waits for VNC Server to connect to it. 

This feature is useful if your computer is protected by a firewall that cannot be configured to allow - or by a router that cannot be configured to forward - network communications, thus preventing incoming connections. In a reverse connection, network communications from the Server user's computer are outgoing.

Note: Reverse connections are not secure and should only be used in a locked-down environment.

Configuring Listening VNC Viewer

Starting Listening VNC Viewer

  •   Under Windows or Mac OS X, search for or navigate to the Listening VNC Viewer program.
  •   Under UNIX, you must start Listening VNC Viewer at the command line. If VNC Viewer is installed on your system, run:

vncviewer –listen [<port>]

If you use the standalone version of VNC Viewer, run:

./<download-file> -listen [<port>]

Configuring and using Listening VNC Viewer

Windows or Mac OS X

The VNC Viewer icon is displayed in the Windows Notification Area or Mac OS X Status bar when Listening VNC Viewer starts (this icon may be hidden by default on Windows). 

Right-clicking this icon reveals the Listening VNC Viewer menu. No configuration is necessary, but if you want to change any settings before a connection is established, select Default Options.... From here, VNC Viewer can be configured before making a connection.

UNIX

Listening VNC Viewer does not have a user interface on UNIX. If you need to configure it before it starts, you must do so at runtime using VNC parameters.

Establishing a reverse connection via VNC Server

Using the user interface

  1.      Open the VNC Server dialog.
  2.      Click More..., then select Connect to Listening VNC Viewer…

    3.      If you are connecting:

  •   Within a private network, enter the network address of the VNC Viewer computer itself. If you do not know what this is, ask the Viewer user to run a command such as ipconfig (Windows) or ifconfig (Linux and Mac OS X).
  •   Over the Internet, enter the network address of the router protecting the Viewer user’s computer. If you do not know what this is, ask the Viewer user to visit www.whatismyip.com.

Listening VNC Viewer listens for reverse connections on port 5500. If a reverse connection fails, it may be because the client computer is protected by a router and/or a firewall and these have not been configured to allow access to Listening VNC Viewer on port 5500.

At the command line

Establishing a connection at the command line differs per platform, and whether VNC Server is already running. Consult our documentation for instructions.

Listening VNC Viewer listens for reverse connections on port 5500. If a reverse connection fails, it may be because the client computer is protected by a router and/or a firewall and these have not been configured to allow access to Listening VNC Viewer on port 5500.


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