Provided by: xtightvncviewer_1.3.10-0ubuntu5_amd64 
NAME
vncviewer - an X viewer client for VNC
SYNOPSIS
vncviewer [options] [host][:display]
vncviewer [options] [host][::port]
vncviewer [options] -listen [display]
vncviewer -help
DESCRIPTION
vncviewer is an Xt-based client application for the VNC (Virtual Network Computing) system. It can
connect to any VNC-compatible server such as Xvnc or WinVNC, allowing you to control desktop environment
of a different machine.
You can use F8 to display a pop-up utility menu. Press F8 twice to pass single F8 to the remote side.
OPTIONS
-help Prints a short usage notice to stderr.
-listen
Make the viewer listen on port 5500+display for reverse connections from a server. WinVNC supports
reverse connections using the "Add New Client" menu option, or the -connect command line option.
Xvnc requires the use of the helper program vncconnect.
-via gateway
Automatically create encrypted TCP tunnel to the gateway machine before connection, connect to the
host through that tunnel (TightVNC-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. See the ENVIRONMENT
section below for the information on configuring the -via option.
-shared
When connecting, specify that a shared connection is requested. In TightVNC, this is the default
mode, allowing you to share the desktop with other clients already using it.
-noshared
When connecting, specify that the session may not be shared. This would either disconnect other
connected clients or refuse your connection, depending on the server configuration.
-viewonly
Disable transfer of mouse and keyboard events from the client to the server.
-fullscreen
Start in full-screen mode. Please be aware that operating in full-screen mode may confuse X window
managers. Typically, such conflicts cause incorrect handling of input focus or make the viewer
window disappear mysteriously. See the grabKeyboard setting in the RESOURCES section below for a
method to solve input focus problem.
-noraiseonbeep
By default, the viewer shows and raises its window on remote beep (bell) event. This option
disables such behaviour (TightVNC-specific).
-user username
User name for Unix login authentication. Default is to use current Unix user name. If this option
was given, the viewer will prefer Unix login authentication over the standard VNC authentication.
-passwd passwd-file
File from which to get the password (as generated by the vncpasswd(1) program). This option
affects only the standard VNC authentication.
-encodings encoding-list
TightVNC supports several different compression methods to encode screen updates; this option
specifies a set of them to use in order of preference. Encodings are specified separated with
spaces, and must thus be enclosed in quotes if more than one is specified. Available encodings, in
default order for a remote connection, are "copyrect tight hextile zlib corre rre raw". For a
local connection (to the same machine), the default order to try is "raw copyrect tight hextile
zlib corre rre". Raw encoding is always assumed as a last option if no other encoding can be used
for some reason. For more information on encodings, see the section ENCODINGS below.
-bgr233
Always use the BGR233 format to encode pixel data. This reduces network traffic, but colors may be
represented inaccurately. The bgr233 format is an 8-bit "true color" format, with 2 bits blue, 3
bits green, and 3 bits red.
-owncmap
Try to use a PseudoColor visual and a private colormap. This allows the VNC server to control the
colormap.
-truecolour, -truecolor
Try to use a TrueColor visual.
-depth depth
On an X server which supports multiple TrueColor visuals of different depths, attempt to use the
specified one (in bits per pixel); if successful, this depth will be requested from the VNC
server.
-compresslevel level
Use specified compression level (0..9) for "tight" and "zlib" encodings (TightVNC-specific). Level
1 uses minimum of CPU time and achieves weak compression ratios, while level 9 offers best
compression but is slow in terms of CPU time consumption on the server side. Use high levels with
very slow network connections, and low levels when working over high-speed LANs. It's not
recommended to use compression level 0, reasonable choices start from the level 1.
-quality level
Use the specified JPEG quality level (0..9) for the "tight" encoding (TightVNC-specific). Quality
level 0 denotes bad image quality but very impressive compression ratios, while level 9 offers
very good image quality at lower compression ratios. Note that the "tight" encoder uses JPEG to
encode only those screen areas that look suitable for lossy compression, so quality level 0 does
not always mean unacceptable image quality.
-nojpeg
Disable lossy JPEG compression in Tight encoding (TightVNC-specific). Disabling JPEG compression
is not a good idea in typical cases, as that makes the Tight encoder less efficient. You might
want to use this option if it's absolutely necessary to achieve perfect image quality (see also
the -quality option).
-nocursorshape
Disable cursor shape updates, protocol extensions used to handle remote cursor movements locally
on the client side (TightVNC-specific). Using cursor shape updates decreases delays with remote
cursor movements, and can improve bandwidth usage dramatically.
-x11cursor
Use a real X11 cursor with X-style cursor shape updates, instead of drawing the remote cursor on
the framebuffer. This option also disables the dot cursor, and disables cursor position updates in
non-fullscreen mode.
-autopass
Read a plain-text password from stdin. This option affects only the standard VNC authentication.
ENCODINGS
The server supplies information in whatever format is desired by the client, in order to make the client
as easy as possible to implement. If the client represents itself as able to use multiple formats, the
server will choose one.
Pixel format refers to the representation of an individual pixel. The most common formats are 24 and 16
bit "true-color" values, and 8-bit "color map" representations, where an arbitrary map converts the color
number to RGB values.
Encoding refers to how a rectangle of pixels are sent (all pixel information in VNC is sent as
rectangles). All rectangles come with a header giving the location and size of the rectangle and an
encoding type used by the data which follows. These types are listed below.
Raw The raw encoding simply sends width*height pixel values. All clients are required to support this
encoding type. Raw is also the fastest when the server and viewer are on the same machine, as the
connection speed is essentially infinite and raw encoding minimizes processing time.
CopyRect
The Copy Rectangle encoding is efficient when something is being moved; the only data sent is the
location of a rectangle from which data should be copied to the current location. Copyrect could
also be used to efficiently transmit a repeated pattern.
RRE The Rise-and-Run-length-Encoding is basically a 2D version of run-length encoding (RLE). In this
encoding, a sequence of identical pixels are compressed to a single value and repeat count. In
VNC, this is implemented with a background color, and then specifications of an arbitrary number
of subrectangles and color for each. This is an efficient encoding for large blocks of constant
color.
CoRRE This is a minor variation on RRE, using a maximum of 255x255 pixel rectangles. This allows for
single-byte values to be used, reducing packet size. This is in general more efficient, because
the savings from sending 1-byte values generally outweighs the losses from the (relatively rare)
cases where very large regions are painted the same color.
Hextile
Here, rectangles are split up in to 16x16 tiles, which are sent in a predetermined order. The data
within the tiles is sent either raw or as a variant on RRE. Hextile encoding is usually the best
choice for using in high-speed network environments (e.g. Ethernet local-area networks).
Zlib Zlib is a very simple encoding that uses zlib library to compress raw pixel data. This encoding
achieves good compression, but consumes a lot of CPU time. Support for this encoding is provided
for compatibility with VNC servers that might not understand Tight encoding which is more
efficient than Zlib in nearly all real-life situations.
Tight Like Zlib encoding, Tight encoding uses zlib library to compress the pixel data, but it
pre-processes data to maximize compression ratios, and to minimize CPU usage on compression. Also,
JPEG compression may be used to encode color-rich screen areas (see the description of -quality
and -nojpeg options above). Tight encoding is usually the best choice for low-bandwidth network
environments (e.g. slow modem connections).
RESOURCES
X resources that vncviewer knows about, aside from the normal Xt resources, are as follows:
shareDesktop
Equivalent of -shared/-noshared options. Default true.
viewOnly
Equivalent of -viewonly option. Default false.
fullScreen
Equivalent of -fullscreen option. Default false.
grabKeyboard
Grab keyboard in full-screen mode. This can help to solve problems with losing keyboard focus.
Default false.
raiseOnBeep
Equivalent of -noraiseonbeep option, when set to false. Default true.
passwordFile
Equivalent of -passwd option.
userLogin
Equivalent of -user option.
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.
encodings
Equivalent of -encodings option.
compressLevel
Equivalent of -compresslevel option (TightVNC-specific).
qualityLevel
Equivalent of -quality option (TightVNC-specific).
enableJPEG
Equivalent of -nojpeg option, when set to false. Default true.
useRemoteCursor
Equivalent of -nocursorshape option, when set to false (TightVNC-specific). Default true.
useBGR233
Equivalent of -bgr233 option. Default false.
nColours
When using BGR233, try to allocate this many "exact" colors from the BGR233 color cube. When using
a shared colormap, setting this resource lower leaves more colors for other X clients. Irrelevant
when using truecolor. Default is 256 (i.e. all of them).
useSharedColours
If the number of "exact" BGR233 colors successfully allocated is less than 256 then the rest are
filled in using the "nearest" colors available. This resource says whether to only use the "exact"
BGR233 colors for this purpose, or whether to use other clients' "shared" colors as well. Default
true (i.e. use other clients' colors).
forceOwnCmap
Equivalent of -owncmap option. Default false.
forceTrueColour
Equivalent of -truecolour option. Default false.
requestedDepth
Equivalent of -depth option.
useSharedMemory
Use 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 the README file for more information on how to
customize the buttons.
debug For debugging. Default false.
rawDelay, copyRectDelay
For debugging, see the README file for details. Default 0 (off).
ENVIRONMENT
When started with the -via option, vncviewer reads the VNC_VIA_CMD environment variable, expands patterns
beginning with the "%" character, and executes result as a command assuming that it would create TCP
tunnel that should be used for VNC connection. If not set, this environment variable defaults to
"/usr/bin/ssh -f -L %L:%H:%R %G sleep 20".
The following patterns are recognized in the VNC_VIA_CMD (note that all the patterns %G, %H, %L and %R
must be present in the command template):
%% A literal "%";
%G gateway host name;
%H remote VNC host name, as known to the gateway;
%L local TCP port number;
%R remote TCP port number.
SEE ALSO
vncserver(1), Xvnc(1), vncpasswd(1), vncconnect(1), ssh(1)
AUTHORS
Original VNC was developed in AT&T Laboratories Cambridge. TightVNC additions were implemented by
Constantin Kaplinsky. Many other people participated in development, testing and support.
Man page authors:
Marcus Brinkmann <Marcus.Brinkmann@ruhr-uni-bochum.de>,
Terran Melconian <terran@consistent.org>,
Tim Waugh <twaugh@redhat.com>,
Constantin Kaplinsky <const@tightvnc.com>
August 2006 vncviewer(1)