Workshops / Background reports / Book introductions
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Workshops / Background reports / Book introductions
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The master of remote control
The VNC Viewer for Amiga by Denis Spach
What does VNC mean? AT&T Laboratories Cambridge [1], who developed this free software, use this abbreviation for Virtual Network Computing. And what does this mean concretely? VNC is a system that allows use of the graphical output (in other words, the "desktop environment", like the Workbench of the Amiga or KDE and GNOME under Linux) of a networked computer on any other computer on this network, whether a local area network or the Internet. It uses the server-client philosophy: The server makes its screen output available to the client, including support for keyboard and mouse input. So the server computer can be remote-controlled from the client, no matter if it is thousands of kilometers or only a few meters away. It hardly matters which operating system is running on both computers. VNC-clients and -server are available for UNIX-like operating systems like Linux, HP/UX and BSD-variants as well as for Windows, DOS, OS/2, BeOS, Geos (e.g. Nokia 9000), PalmOS and, thanks to several capable programmers, also for the Amiga.
Joerg Dietrich wrote 'VVA', a "VNC viewer for Amiga", which has been taken over by Denis Spach [2] with version 0.2 and has currently reached version 0.9.6. By the way, on the homepage of Denis Spach, you'll also find a VNC- and X11-server for the Amiga. But this article is limited to the installation and configuration of the VNC viewer for the Amiga. It'll show how the Amiga can capture the graphical output of Linux and Windows and thus get complete control of those computers.
Your Amiga should be able to display at least 256 colors, so you should have at least AGA or a graphics board with Cybergraphics or Picasso96. Furthermore, you should have at least an MC68020 CPU in your computer and AmigaOS 3.0 or better installed. To communicate with other computers, you need a TCP/IP stack like Miami, AmiTCP V3 or better or Genesis. Of course, somewhere in the reachable network, a computer must be running a VNC server. And, last but not least, reqtools.library is needed.
After downloading and unpacking the archive on your computer, the installation is complete. Double clicking on the 'vva' icon opens a window with many wa-xx icons in MagicWB-look, containing several preconfigured start files for the VNC viewer. You can choose between output in a window on the Workbench, the Workbench background or on a separate screen in either 8, 16 or 32-bit color depth. You can change the Tooltypes in the icons to suit your needs or create your own project icons with the appropriate options.
Before the VNC viewer can do anything useful, you first have to install a suitable VNC server on the computer to be remote-controlled.
You'll find the needed packages on the VNC web sites of AT&T [3] in the area DOWNLOAD. Select the required packages for your operating system and install them on your computer. Alternatively, you might try looking on your Linux CD set. SuSe Linux, for example, already includes recent packages for the VNC server as well as for the viewer. Once the packages are installed (for example by using RPM or a tool like YAST under SuSE), you can start the VNC server from the shell. First, it wants to know a password which the client will later need to authorize itself.
You should configure at least the display to be used. In our case, we will use display No. 2. The screen resolution shall be 800 x 600 pixels, so we can open a window on Workbench with 1024 x 768 pixels. If you choose a screen resolution higher than the current Workbench resolution, 'vva' will open its own screen.
If you want to stop the VNC server, enter "vncserver -kill :2" into the shell to terminate the current session.
If you have a recent SuSe distribution, you do not need to download any files for Windows9x. On the first CD or the DVD, you'll find a VNC server and viewer for Windows9x in the directory '/dosutils/vnc'. Otherwise, you'll find the needed files on the AT&T web site [3]. An installation routine is included in the package. Before you start it for the first time, you'll have to prepare the installation by running "Start/Programs/Vnc/Administrative Tools/Install Default Registry Settings" and ".../Install WinVNC Service". Again, the VNC server will ask for a password to prevent unauthorized access. It is also necessary to choose a display number. Besides the automatic assignment, you can also set it manually, which is what we'll do. Just like Linux, we'll use display No. 2 and save changes by clicking on "OK".
From now on, the VNC server waits in the background for the VNC viewer to contact it.
You can set up many different configurations, but for the sake of speed, we'll settle for a simple example. For more in-depth information, refer to the documentation of 'vva' and the VNC web site [3].
Let's choose the Linux computer: It is reachable under the IP address '192.168.0.3' or the host name 'linux.wing.de' and its VNC server exports the output on display 2, as configured. We want to see the output on a window on our Amiga Workbench running in 8 bit color depth.
To do this, we'll use the predefined icon 'vva-sharepens'. Now open the icon information. We have to make the following changes: Under HOST, put the IP address or name of the computer to be controlled, either HOST=192.168.0.3 or HOST=linux.xwing.de. The PORT also contains the display number. Since we are using display No. 2, the entry must be PORT=5902. If you want to use display No. 1, the entry PORT=5901 would be correct.
With the option SCREENMODE, you can define the mode of the screen to be opened. You'll have to use hexadecimal notation. To obtain this number, the 'vva' package includes a tool called 'mid'. If, like in our case, the SCREENMODE option is deactivated, the screenmode requester will be opened automatically. We leave the other options just as they are. You can find further information about these options in the documentation of 'vva'. After double clicking the modified icon, you'll be confronted by the password request.
Enter the password you have set up on the server, then choose the desired screenmode (if a window on the Workbench can't be opened) and marvel at a window containing the screen output of the "tapped" computer.
Virtual Network Computing is a fascinating way to control networked computers. The exported user interface makes it very easy to control the remote computer. It opens for a wide range of applications.
Although the program 'vva' has only reached version 0.9.6, it is still a very reliable and performing. A fine piece of Amiga software. Highly recommended.
Uwe Pannecke <Uwe.Pannecke@t-online.de>
