xtightvncviewer
An X viewer client for VNC
root@kali:~# man xtightvncviewer
vncviewer(1) TightVNC vncviewer(1)
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 ma-
chine 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 desk-
top 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 con-
nection, 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-spe-
cific).
-passwd passwd-file
File from which to get the password (as generated by the vnc-
passwd(1) program). This option affects only the standard VNC au-
thentication.
-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 differ-
ent 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" en-
codings (TightVNC-specific). Level 1 uses minimum of CPU time and
achieves weak compression ratios, while level 9 offers best com-
pression 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" encod-
ing (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-spe-
cific). 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-spe-
cific). 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 dis-
ables 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 informa-
tion in VNC is sent as rectangles). All rectangles come with a header giv-
ing 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 identi-
cal pixels are compressed to a single value and repeat count. In
VNC, this is implemented with a background color, and then specifi-
cations 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 lo-
cal-area networks).
Zlib Zlib is a very simple encoding that uses zlib library to compress
raw pixel data. This encoding achieves good compression, but con-
sumes a lot of CPU time. Support for this encoding is provided for
compatibility with VNC servers that might not understand Tight en-
coding 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 com-
pression may be used to encode color-rich screen areas (see the de-
scription 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 re-
sources, 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.
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" col-
ors 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' col-
ors).
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 win-
dow. 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 ma-
chine 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 envi-
ronment 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 addi-
tions were implemented by Constantin Kaplinsky. Many other people partici-
pated 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)