vncviewer - VNC viewer for X

vncviewer [options] [host][:display#]

vncviewer [options] -listen [display#]

vncviewer is a viewer (client) for Virtual Network Computing. This manual page documents the version for the X window system.

If you run the viewer with no arguments it will prompt you for a VNC server to connect to. Alternatively, specify the VNC server as an argument, e.g.:

vncviewer snoopy:2

where 'snoopy' is the name of the machine, and '2' is the display number of the VNC server on that machine. Either the machine name or display number can be omitted. So for example ":1" means display number 1 on the same machine, and "snoopy" means "snoopy:0" i.e. display 0 on machine "snoopy".

If the VNC server is successfully contacted, you will be prompted for a password to authenticate you. If the password is correct, a window will appear showing the desktop of the VNC server.

From version 3.3.4 onwards, the viewer tests the speed of the connection to the server and chooses the encoding and pixel format appropriately. This makes it much easier to use than previous versions where the user had to specify arcane command line arguments.

The viewer starts out assuming the link is slow, using an 8-bit pixel format and using the encoding with the best compression. If it turns out that the link is fast enough it switches to full-colour mode and will use an encoding which compresses less but is faster to generate, thus improving the interactive feel. Automatic selection can be turned off with the -noauto option, or from the popup window.

The viewer has a popup window containing a set of buttons which perform various actions. It is usually brought up by pressing F8, but this is customisable, as is the entire contents of the popup. Actions which buttons in the popup window can perform include:

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switching in and out of full-screen mode

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quitting the viewer

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generating arbitrary key and mouse events, e.g. sending ctrl-alt-del

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transferring the clipboard to or from the VNC server

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switching on or off automatic selection of encoding and pixel format

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switching 8-bit mode on or off

By default, key presses in the popup window get sent to the VNC server and dismiss the popup. So to get an F8 through to the VNC server simply press it twice.

See the sections on customisation below for how to customise the contents of the popup window.

A full-screen mode is supported. This is particularly useful when connecting to a remote screen which is the same size as your local one. If the remote screen is bigger, you can scroll by bumping the mouse against the edge of the screen.

Unfortunately this mode doesn't work completely with all window managers, since it breaks all the X window management conventions. It tends to work better when the viewer is started in full-screen mode than when switching to it from normal mode.

You can get a list of options by giving -h as an option to vncviewer. Most of these options can also be specified as X resources - see the section on customisation below.

-via Xgateway

Makes the connection go though SSH to a gateway host. The gateway should be the target host for best connection secrecy.

-listen [display-number]

Causes vncviewer to listen on port 5500 + display-number for reverse connections from a VNC server. WinVNC supports reverse connections initiated using the 'Add New Client' menu option or the '-connect' command-line option. Xvnc supports reverse connections with a helper program called vncconnect.

-shared

When you make a connection to a VNC server, all other existing connections are normally closed. This option requests that they be left open, allowing you to share the desktop with someone already using it.

-display Xdisplay

Specifies the X display on which the VNC viewer window should appear.

-passwd password-file

If you are on a filesystem which gives you access to the password file used by the server, you can specify it here to avoid typing it in. It will usually be "~/.vnc/passwd".

-viewonly

Specifies that no keyboard or mouse events should be sent to the server. Useful if you want to view a desktop without interfering; often needs to be combined with -shared.

-fullscreen

Start in full-screen mode.

-geometry geometry

Standard X position and sizing specification.

-noauto

Turn off the automatic selection of encoding and pixel format. Normally the viewer tests the speed of the connection to the server and chooses the encoding and pixel format appropriately.

-8bit, -bgr233

This option implies -noauto. Tells the VNC server to send pixels which are only 8 bits deep. If your server desktop is deeper than this then it will translate the pixels before sending them. Less data will generally be sent over then network, which can be a big advantage on slow links, but you may get some colour mismatches. "BGR233" means an 8-bit true colour pixel format, with the most significant two bits of each byte representing the blue component, the next three bits representing green and the least significant three representing red. This format is also used by the java client.

-encodings encodings

This option implies -noauto. This option specifies a list of encodings to use in order of preference, separated by spaces. For example, to use only raw and CopyRect, specify "raw copyrect".

-owncmap

Try to use a PseudoColor visual and a private colormap - this allows the VNC server to control the colormap.

-truecolour

Try to use a TrueColor visual.

-depth d

This is only useful on a (real) X server which supports multiple TrueColor depths. On such a display vncviewer will try to find a Visual of the given depth. If successful this means that the appropriate pixel format will be requested from the VNC server. You cannot use this to force a particular depth from the VNC server. The only option which does this is -bgr233.

The behaviour of vncviewer is extremely customisable using X resources. You can set X resources by any of the usual means - in an app-defaults file such as ".Xresources", or on the command line with the -xrm option, e.g.: vncviewer -xrm '*nColours:64' See the X window system documentation for details.

The application resources are:

shareDesktop (option -shared)

Whether to leave other viewers connected. Default false.

viewOnly (option -viewonly)

Block mouse and keyboard events. Default false.

fullScreen (option -fullscreen)

Full screen mode. Default false.

passwordFile (option -passwd)

File from which to get the password (as generated by the vncpasswd program). Default is null, i.e. to request password from the user.

passwordDialog

Whether to use a dialog box to get the password (true) or get it from the tty (false). Irrelevant if passwordFile is set. Default false.

autoDetect (option -noauto turns off)

Whether to automatically select encoding and pixel format based on the speed of the connection to the server. Default true.

encodings (option -encodings)

A list of encodings to use in order of preference, separated by spaces. Default is null.

useBGR233 (option -8bit or -bgr233)

Always use the BGR233 (8-bit) pixel format on the wire, regardless of the visual. Default is false, although autoDetect may choose BGR233 anyway, and BGR233 is always used for non-TrueColor visuals with forceOwnCmap false.

nColours

When using BGR233, try to allocate this many "exact" colours from the BGR233 colour cube. When using a shared colormap, setting this resource lower leaves more colours for other X clients. Irrelevant when using truecolour. Default is 256 (i.e. all of them).

useSharedColours

If the number of "exact" BGR233 colours successfully allocated is less than 256 then the rest are filled in using the "nearest" colours available. This resource says whether to only use the "exact" BGR233 colours for this purpose, or whether to use other clients' "shared" colours as well. Default true (i.e. use other clients' colours).

forceOwnCmap (option -owncmap)

Try to use a PseudoColor visual and a private colormap - this allows the VNC server to control the colormap. Default false.

forceTrueColour (option -truecolour)

Try to use a TrueColor visual. Default false.

requestedDepth (option -depth)

If forceTrueColour is true, try to use a visual of this depth. Default 0 (i.e. any depth).

useSharedMemory

Whether to use the MIT shared memory extension if on the same machine as the X server. Default true.

wmDecorationWidth, wmDecorationHeight

The total width and height taken up by window manager decorations. This is used to calculate the maximum size of the VNC viewer window. Default is width 4, height 24.

bumpScrollTime, bumpScrollPixels

When in full screen mode and the VNC desktop is bigger than the X display, scrolling happens whenever the mouse hits the edge of the screen. The maximum speed of scrolling is bumpScrollPixels pixels every bumpScrollTime milliseconds. The actual speed of scrolling will be slower than this, of course, depending on how fast your machine is. Default 20 pixels every 25 milliseconds.

popupButtonCount

The number of buttons in the popup window. See below for how to customise the buttons.

rawDelay

This is useful for debugging VNC servers by checking exactly which parts of the screen are being updated. For each update rectangle vncviewer puts up a black rectangle for the given time in milliseconds before putting up the pixel data. This only highlights pixel data sent using the raw encoding. Default 0 (i.e. don't do it).

copyRectDelay

Similar to rawDelay, but highlights the areas copied using the copyrect encoding.

CUSTOMISING THE POPUP WINDOW

CUSTOMISING THE DESKTOP WINDOW

X RESOURCE ACTIONS

vncviewer uses the original X11 Athena widget set which is a little bit out of date. On the plus side it is available in every installation of the X window system.

vncconnect(1), vncpasswd(1), vncserver(1), Xvnc(1)

http://www.realvnc.com

Tristan Richardson, RealVNC Ltd.

VNC was originally developed by the RealVNC team while at Olivetti Research Ltd / AT&T Laboratories Cambridge. It is now being maintained by RealVNC Ltd. See http://www.realvnc.com for details.