Showing posts with label RealVNC. Show all posts
Showing posts with label RealVNC. Show all posts

VNC Basics

Virtual Network Computing, or "VNC," is software used to connect remotely to a computer system. This allows a user to see and control one computer from multiple locations. Because this control is transmitted over the Internet, the computer can be viewed from anywhere in the world.

VNC software is fairly uncomplicated and easy to use. Many operating systems, including Microsoft Windows, already include simple VNC programs. These applications allow users to connect remotely and operate another computer loaded with the same software.

VNCs allow computers to become remotely sharable. This means that several different users, each in separate locations, can view a computer desktop at the same time. VNC software makes training, monitoring and troubleshooting easy by making remote access flexible.

VNC Interface

Most VNC systems are controlled from a simple graphic user interface. Once the software has been installed on a remote computer, it can be accessed from any location. A server constantly monitors inputs and outputs from one computer, and updates them to the second location.

The interface for most VNCs can operate from any operating system, such as Windows, Macintosh, or Unix. Because information is transmitted over the Internet, the system eliminates many of the traditional cross-platform problems. Just as a website can be viewed on many different operating systems, so can VNC control operate from many different computer types. While "VNC" is a generic term for this type of software, many brands of the software exist, with packages available for all major operating systems.

The connection used to interface data is protected by a password. This prevents unauthorized users from controlling a remote computer. Once the connection is established, information begins to be exchanged. Details on mouse location, keyboard entry, and screen updates are fed over the secure connection, keeping the computers synchronized.

VNC Uses

VNC software began as a way to monitor and troubleshoot systems remotely, and this feature remains a common use. Computer technicians can provide tech support using VNC without being physically present. If a user is having a problem installing software, for example, a support professional can connect to her computer, see the problem, and talk the user through the solution.

Use of VNC software has also expanded to other areas. Remote work has become an increasingly popular option. VNC allows workers to access and control software without being in the office. For instance, using VNC, a programmer in India can easily control a desktop computer in California, collaborating with colleagues and working on a project remotely.

Overview

VNC consists of two components. A server, which runs on the computer you want to remotely access, and a viewer, which runs on the computer you are sitting in front of. There are two important features of VNC:
  • The server and the viewer may be on different machines and on types of computer. The protocol which connects the server and viewer is simple, open, and platform independent.
  • No state is stored at the viewer. Breaking the viewer's connection to the server and then reconnecting will not result in any loss of data. Because the connection can be remade from somewhere else, you have easy mobility.
So to get started with VNC you need to run a server, and then connect to it with a viewer. First of all, you have to download and install the software on the platforms you want to use. The screenshots on this page refer to VNC Free Edition 4.1, but the general concepts apply to all versions of Free Edition and Enterprise Edition.

Networking

VNC software requires a TCP/IP connection between the server and the viewer. This is the standard networking protocol on LANs, WANs, broadband and dialup ISP. Each computer has a unique IP address and may also have a name in the DNS. You will need to know the IP address or name of the server when you connect a viewer to it.
Sometimes the IP address is fixed, and sometimes it is issued to you dynamically by your ISP. If it is allocated dynamically, you might consider using a third party DNS management service. Try typing "dynamic dns management service" into a google.

Running a Windows server

Installing the Windows server, WinVNC, should create a RealVNC group in your Start... menu. Run the VNC server.

If this is the first time you've used a VNC server on this machine you'll be prompted to set a password, which you'll need when you connect to the machine from a remote location. A small icon will appear in the system tray, and by right-clicking on this you can control most aspects of the server.

winvnc4_traymenu

The IP address of the computer running the VNC server can be found by hovering over the tray icon in the system tray. Unless this computer has a DNS name, you will need to specify this number to the viewer when you connect.

winvnc4_ipaddr

You can now go to another machine and connect a viewer to the server.

Running a Unix server

To X applications, a VNC server appears just like the standard X display you sit in front of, but without a physical screen attached. The applications don't know this, they just carry on running whether or not a viewer is connected. You can start a new VNC server on a Unix machine by typing:
 
vncserver

If you haven't run a VNC server before you will be prompted for a password, which you will need to use when connecting to this server. All your servers on the same Unix machine will use the same password, and you can change it at a later date using
 
vncpasswd

With a normal X system, the main X display of a workstation called ’snoopy’ is usually snoopy:0. You can also run as many VNC servers on a Unix machine as you like, and they will appear as snoopy:1, snoopy:2 etc, as if they were just additional displays. Normally vncserver will choose the first available display number and tell you what it is, but you can specify a display number if you always wish to use the same one:
vncserver :2

You can cause applications to use a VNC server rather than the normal X display them by setting the DISPLAY environment variable to the VNC server you want, or by starting the application with the -display option.

For example:
xterm -display snoopy:2 &
You can kill a Unix VNC server using, for example:
vncserver -kill :2

Full instructions for installing and running VNC server for Unix can be found in the RealVNC Site documentation.
Nothing will appear immediately as a result of starting a Unix VNC server. To see anything you need to connect a viewer to the server, see below.

Running a viewer

You can run the Windows viewer the RealVNC group on the Start... menu.
winvncviewer4_startmenu

In this case, you will be prompted for the host name (VNC server name) and display number:


winvncviewer4_display

Enter it and click OK, and you will be prompted for your password, after which you should see the remote display. If you are connecting to a Windows or Mac server, the display number will be 0 unless you have explicitly changed it, and can be omitted.

You can run the viewer on Unix and Windows by typing at the command line:
vncviewer snoopy:2

You need to specify the name of the VNC server and the number of the desktop. If, for example, you have started a server as display 2 on a machine called 'snoopy'. Remember that if you are connecting to a Windows or Mac server, the display number will be 0 unless you have explicitly changed it, and can be omitted.

If the machine running the server does not have a DNS entry, you probably won't be able to use the name and will have to replace snoopy with its IP address, for example something that looks like 123.456.78.9.

Using a web browser as a viewer

The VNC servers also contain a small web server. If you connect to this with a web browser, you can download the Java version of the viewer, and use this to view the server. You can then see your desktop from any Java-capable browser, unless you are using a proxy to connect to the web. The server listens for HTTP connections on port 5800+display number. So to view display 2 on machine 'snoopy', you would point your web browser at:

http://snoopy:5802/

The applet will prompt you for your password, and should then display the desktop.