Section: Virtual Network Computing (1)
vncviewer - VNC viewer for X
is a viewer (client) for Virtual Network Computing. This manual page documents
version 4 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.:
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".
As another quick way to start a connection to a VNC server, specify a .tigervnc
configuration file as an argument to the viewer, e.g.:
where './some.tigervnc' is an existing and valid TigerVNC configuration file.
The file name needs to include a path separator. Additional options may be
given too, but the given configuration file will overwrite any conflicting
If the VNC server is successfully contacted, you will be prompted for a
password to authenticate you. You can also add 'VNC_USERNAME' and 'VNC_PASSWORD'
to environment variables. If the password is correct, a window will appear
showing the desktop of the VNC server.
AUTOMATIC PROTOCOL SELECTION
The viewer tests the speed of the connection to the server and chooses the
encoding and pixel format (color level) appropriately. This makes it much
easier to use than previous versions where the user had to specify arcane
command line arguments.
The viewer normally starts out assuming the link is slow, using the
encoding with the best compression. If it turns out that the link is
fast enough it switches to an encoding which compresses less but is
faster to generate, thus improving the interactive feel.
The viewer normally starts in full-color mode, but switches to
low-color mode if the bandwidth is insufficient. However, this only
occurs when communicating with servers supporting protocol 3.8 or
newer, since many old servers does not support color mode changes
Automatic selection can be turned off by setting the
AutoSelect parameter to false, or from the options dialog.
The viewer has a popup menu containing entries which perform various actions.
It is usually brought up by pressing F8, but this can be configured with the
MenuKey parameter. Actions which the popup menu can perform include:
switching in and out of full-screen mode
quitting the viewer
generating key events, e.g. sending ctrl-alt-del
accessing the options dialog and various other dialogs
By default, key presses in the popup menu get sent to the VNC server and
dismiss the popup. So to get an F8 through to the VNC server simply press it
FULL SCREEN MODE
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
You can get a list of parameters by giving -h
as a command-line option
to vncviewer. Parameters can be turned on with -param
or off with
=0. Parameters which take a value can be specified as
. Other valid forms are param=value
. Parameter names are
Many of the parameters can also be set graphically via the options dialog box.
This can be accessed from the popup menu or from the "Connection details"
- -display Xdisplay
Specifies the X display on which the VNC viewer window should appear.
- -geometry geometry
Initial position of the main VNC viewer window. The format is
, where `+' signs can be replaced with `-' signs to specify offsets from the
right and/or from the bottom of the screen. Offsets are optional and the
window will be placed by the window manager by default.
- -listen [port]
Causes vncviewer to listen on the given port (default 5500) 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
- -SecurityTypes sec-types
Specify which security schemes to attempt to use when authenticating with
the server. Valid values are a comma separated list of None,
VncAuth, Plain, TLSNone, TLSVnc, TLSPlain,
X509None, X509Vnc and X509Plain. Default is to attempt
every supported scheme.
- -passwd, -PasswordFile 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
- -X509CA path
Path to CA certificate to use when authenticating remote servers using any
of the X509 security schemes (X509None, X509Vnc, etc.). Must be in PEM
format. Default is $HOME/.vnc/x509_ca.pem, if it exists.
- -X509CRL path
Path to certificate revocation list to use in conjunction with
-X509CA. Must also be in PEM format. Default is
$HOME/.vnc/x509_crl.pem, if it exists.
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.
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
Accept clipboard changes from the server. Default is on.
Set the primary selection as well as the clipboard selection.
Default is on.
- -MaxCutText bytes
The maximum size of a clipboard update that will be accepted from a server.
Default is 262144.
Send clipboard changes to the server. Default is on.
Send the primary selection to the server as well as the clipboard
selection. Default is on.
Maximize viewer window.
Start in full-screen mode.
Use all local monitors and not just the current one when switching to
Pass special keys (like Alt+Tab) directly to the server when in full-screen
- -DesktopSize widthxheight
Instead of keeping the existing remote screen size, the client will attempt to
switch to the specified since when connecting. If the server does not support
the SetDesktopSize message then the screen will retain the original size.
Dynamically resize the remote desktop size as the size of the local client
window changes. Note that this may not work with all VNC servers.
Use automatic selection of encoding and pixel format (default is on). Normally
the viewer tests the speed of the connection to the server and chooses the
encoding and pixel format appropriately. Turn it off with -AutoSelect=0.
- -FullColor, -FullColour
Tells the VNC server to send full-color pixels in the best format for this
display. This is default.
- -LowColorLevel, -LowColourLevel level
Selects the reduced color level to use on slow links. level can range
from 0 to 2, 0 meaning 8 colors, 1 meaning 64 colors (the default), 2 meaning
256 colors. Note that decision if reduced color level is used is made by
vncviewer. If you would like to force vncviewer to use reduced color level
use -AutoSelect=0 parameter.
- -PreferredEncoding encoding
This option specifies the preferred encoding to use from one of "Tight", "ZRLE",
"hextile" or "raw".
Disable lossy JPEG compression in Tight encoding. Default is off.
- -QualityLevel level
JPEG quality level. 0 = Low, 9 = High. May be adjusted automatically if
-AutoSelect is turned on. Default is 8.
- -CompressLevel level
Use specified lossless compression level. 0 = Low, 9 = High. Default is 2.
Use custom compression level. Default if CompressLevel is specified.
Show the dot cursor when the server sends an invisible cursor. Default is off.
- -PointerEventInterval time
Time in milliseconds to rate-limit successive pointer events. Default is
17 ms (60 Hz).
Emulate middle mouse button by pressing left and right mouse buttons
simultaneously. Default is off.
- -Log logname:dest:level
Configures the debug log settings. dest can currently be stderr or
stdout, and level is between 0 and 100, 100 meaning most verbose
output. logname is usually * meaning all, but you can target a
specific source file if you know the name of its "LogWriter". Default is
- -MenuKey keysym-name
This option specifies the key which brings up the popup menu. The currently
supported list is: F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, Pause,
Scroll_Lock, Escape, Insert, Delete, Home, Page_Up, Page_Down). Default is F8.
- -via gateway
Automatically create encrypted TCP tunnel to the gateway machine
before connection, connect to the host through that tunnel
(TigerVNC-specific). By default, this option invokes SSH local port
forwarding, assuming that SSH client binary can be accessed as
/usr/bin/ssh. Note that when using the -via option, the host
machine name should be specified as known to the gateway machine, e.g.
"localhost" denotes the gateway, not the machine where vncviewer
was launched. The environment variable VNC_VIA_CMD can override
the default tunnel command of
/usr/bin/ssh -f -L "$L":"$H":"$R" "$G" sleep 20. The tunnel
command is executed with the environment variables L, H,
R, and G taken the values of the local port number, the remote
host, the port number on the remote host, and the gateway machine
Display a dialog with any fatal error before exiting. Default is on.
Default configuration options. This file must have a "magic" first line of
"TigerVNC Configuration file Version 1.0" (without quotes), followed by simple
<setting>=<value> pairs of your choosing. The available settings are those
shown in this man page.
Default CA certificate for authenticating servers.
Default certificate revocation list.
Tristan Richardson, RealVNC Ltd. and others.
VNC was originally developed by the RealVNC team while at Olivetti
Research Ltd / AT&T Laboratories Cambridge. TightVNC additions were
implemented by Constantin Kaplinsky. Many other people have since
participated in development, testing and support. This manual is part
of the TigerVNC software suite.