VNC User Guide

2. If you have a valid support and upgrades contract to use VNC Server (Enterprise) or VNC Server (Personal), contact Technical Support. Start with Technical Support for more information.

3. If all else fails, and providing you are in a secure environment and a host computer user is present, you can ask that person to connect to you. For more information, see Establishing a reverse connection.

Licensing VNC Server

VNC Server must be licensed. If it is not, users cannot connect.

Note: VNC Viewer does not need to be licensed.

If VNC Server is not licensed, the status bar on the VNC Server dialog turns red:

Click the Show button to see more information:

Click the Resolve button to start the process of licensing VNC Server, and follow the instructions. See Licensing VNC Server for more information.

Connecting within a private network

If both client and host computers are managed within a closed network environment such as a LAN or VPN, you are connecting within a private network. This is common in corporate and other enterprise environments, and may also be the case if you are connecting two computers at home.

To connect within a private network, enter the network address of the host computer itself in the VNC Viewer dialog, for example:

If you do not know the network address of the host computer:

• And you do not have access to it, you will need to consult your system administrator or a host computer user.

• And you do have access to the host computer:

a. Open the VNC Server dialog. More on this dialog.

b. Examine the appropriate section of the Get Started section:

Connecting over the Internet

If you are connecting over the Internet (for example, to friends and family, over a cellular network, or in to the office on the move), it is very likely that the host computer will be protected by a router or similar device acting as a communication gateway and public interface.

Note: The host computer is also very likely to be protected by a firewall. For more information, see Allowing network communications through a firewall.

To connect over the Internet, enter the network address of the router in the VNC Viewer dialog, for example:

If you do not know the network address of a host computer’s router:

• And you do not have access to the host computer, you will need to ask a host computer user either to follow the instructions below, or to visit www.whatismyip.com.

• And you do have access to the host computer:

a. Open the VNC Server shortcut menu. More on this menu.

b. Choose Information Center and, on the Diagnostics tab, click the Test Internet Connection button.

c. Click the Start button. RealVNC attempts to contact the host computer over the Internet. Providing the host computer is connected to the Internet, the network address of an intermediary device is revealed:

VNC Server appears to be behind a NAT router with IP address 212.44.6.81. You will need to configure that router to forward port 5900 to this computer before you can connect to VNC Server over the Internet.

Configuring a router to forward network communications

In a typical home or small office environment, a router assigns a private network address to an internal computer. You should also be aware that VNC Server listens for network communications on a particular port. The router must be configured to forward communications from VNC Viewer to the correct port at the correct private network address. This procedure is known as port forwarding.

Note: Port forwarding instructions are specific to routers. If you do not have access to the host computer, ask a host computer user to consult the manufacturer’s documentation, or visit www.portforward.com.

Note that a router may act as a public interface to more than one computer in a home or small office environment. If you want to connect to multiple host computers, then VNC Server must be running on each and listening on a different port. The router must be configured to distinguish between host computers using port numbers.

Consider the following example:

A. Router with a network address assigned by an ISP, for example 212.44.6.81. B. Host computer with a network address assigned by the router, for example 192.168.0.1. VNC Server is listening on the default port, 5900. C. Host computer with a network address assigned by the router, for example 192.168.0.2. VNC Server has been configured to listen on port 5901. D. Client computer running VNC Viewer.

In this scenario, the router must be configured to forward port 5900 to host computer B at 192.168.0.1 and port 5901 to host computer C at 192.168.0.2.

When you connect to either host computer from VNC Viewer, you must enter the network address of the router: 212.44.6.81. In addition, to connect to host computer C, you must qualify the router’s network address with the port number: 212.44.6.81:1. To find out why this is, see Qualifying a network address with a port number.

Qualifying a network address with a port number

VNC Server listens for network communications on a particular port. By default, and providing it is available when VNC Server starts, this is port 5900 for connection requests. This port is registered for use by VNC Server with the Internet Assigned Numbers Authority (IANA).

Note: For more information on ports, see Configuring ports.

If VNC Server is listening on any other port, you must qualify the network address of the host computer (or router) with the port number when you connect from VNC Viewer, for example:

If you know that VNC Server is listening on a port between 5901 and 5999, append a colon (:) and an identifying number (1 through 99) to the network address, for example:

johndoe:1
192.168.0.133:1
[2001:db8::1]:1

If you know that VNC Server is listening on any other port, append a double colon (::) and the full port number to the network address, for example:

johndoe::6001
192.168.0.133::6001
[2001:db8::1]::6001

If you do not know on which port VNC Server is listening:

• And you do not have access to the host computer, you will need to consult your system administrator or a host computer user.

• And you do have access to the host computer:

a. Open the VNC Server dialog. See how to do this.

b. Examine the appropriate section of the Get Started section:

In this example, VNC Server is running on host computer 192.168.0.133 and listening on port 5901.

Allowing network communications through a firewall

If the host computer is protected by a firewall, then the firewall must be configured to allow incoming network communications to the port on which VNC Server is listening. To find out which port this is, see Qualifying a network address with a port number.

The firewall might be automatically configured by the operating system of the host computer. If not, you will probably see the following error message when you connect from VNC Viewer:

Connection timed out (10060)

The instructions for adding exceptions for ports are specific to firewalls. If you do not have access to the host computer, ask a host computer user to consult the manufacturer’s documentation.

Miscellaneous connection messages

This section explains various error messages you might see.

Failing to authenticate correctly

If you see the following error message:

Either the username was not recognized, or the password was incorrect.

then you have not authenticated correctly to VNC Server. Note that user names and passwords are case-sensitive.

If you do not know the correct user name or password, and you do not have access to the host computer, you will need to consult your system administrator or a host computer user. If you do have access to the host computer, and sufficient privileges to configure VNC Server, you may be able to relax the authentication rules. For more information, see Relaxing the authentication rules.

Failing to authenticate as ‘you’

If you see the following error message:

Access is denied.

then VNC Server has been configured to require the credentials of a host computer user. Your user name and password, however, have not been added to the authentication list.

If this is the case and you do not have access to the host computer, you will need to consult your system administrator or a host computer user. If you do have access to the host computer, and sufficient privileges to configure VNC Server, you may be able to register your credentials. For more information, see Managing users and groups in the authentication list.

Connecting from an unauthorized computer

If you see the following error message:

The connection closed unexpectedly.

then it could be that VNC Server has been configured to prevent connections from the client computer you are using.

If this is the case and you do not have access to the host computer, you will need to consult your system administrator or a host computer user. If you do have access to the host computer, and sufficient privileges to configure VNC Server, you may be able to unblock your client computer. For more information, see Preventing connections from particular client computers.

Alternatively, you may be able to connect from a different client computer.

Being rejected by a host computer user

If you see the following error message:

Connection rejected by host computer user.

then VNC Server has been configured to display connection prompts to a host computer user, and your request has either been explicitly rejected, or has timed out (this could either be because the prompt was deliberately ignored, or because no host computer user is actually present).

If this is the case and you do not have access to the host computer, you will need to consult your system administrator or a host computer user. If you do have access to the host computer, and sufficient privileges to configure VNC Server, you may be able to bypass host computer connection prompts. For more information, see Preventing particular users connecting.