Ubuntu Manpage: Xvnc - an X server providing VNC connectivity

Provided by: tightvncserver_1.3.10-9_amd64

NAME

       Xvnc - an X server providing VNC connectivity

SYNOPSIS

       Xvnc   [:display]  [-geometry  widthxheight]  [-depth  depth] [-pixelformat rgbNNN|bgrNNN] [-udpinputport
              port] [-rfbport port] [-rfbwait time] [-nocursor] [-rfbauth passwd-file] [-httpd  dir]  [-httpport
              port]  [-deferupdate  time]  [-economictranslate]  [-lazytight]  [-desktop  name]  [-alwaysshared]
              [-nevershared]   [-dontdisconnect]   [-viewonly]   [-localhost]   [-interface   ipaddr]   [-inetd]
              [-compatiblekbd] [X-options...]

DESCRIPTION

       Xvnc  is  a  VNC (Virtual Network Computing) server. It acts like an X server with a virtual display. The
       display can be seen by a VNC viewer application, which  may  be  running  on  a  different  machine:  see
       vncviewer(1). Xvnc is built inside the source code tree of XFree86, and shares many options with it.

       Normally, you don't need to start Xvnc manually; use the vncserver(1) wrapper script instead. This script
       sets reasonable defaults for Xvnc session, checks many error conditions etc.

       Please read the BUGS section if you plan to use VNC on an untrusted network.

OPTIONS

Xvnc supports many standard X server options and a number of VNC-specific options. To see what standard X
server options are supported, please look at the Xvnc -help output and read the Xserver(1) manual page
for details on those options.

The VNC-specific options are as follows:

-geometry widthxheight
Set desktop width and height.

-depth depth
Set the colour depth of the visual to provide, in bits per pixel. Must be a value between 8 and
32.

-pixelformat rgbNNN|bgrNNN
Set colour format for pixels representation. The viewer can do the conversion to any other pixel
format, but it is faster if the depth and pixel format of the server is the same as the equivalent
values on the viewer display.

-udpinputport port
UDP port for keyboard/pointer data.

-rfbport port
TCP port for RFB protocol. The RFB protocol is used for communication between VNC server and
clients.

-rfbwait time
Maximum time, in milliseconds, to wait for an RFB client (VNC viewer).

-nocursor
Don't put up a pointer cursor on the desktop.

-rfbauth passwd-file
Use authentication on RFB protocol from the specified file. The passwd-file can be created using
the vncpasswd(1) utility.

-httpd dir
Serve files via HTTP protocol from the specified directory. Normally, Java viewer classes are
stored in such directory.

-httpport port
TCP port on which Xvnc should listen for incoming HTTP connections (to allow access to the desktop
from any Java-capable browser).

-deferupdate time
Time in milliseconds, to defer screen updates (default 40). Deferring updates helps to coalesce
many small desktop changes into a few larger updates thus saving network bandwidth.

-economictranslate
Use less memory-hungry pixel format translation.

-lazytight
Disable the "gradient" filter in Tight encoding (TightVNC-specific). The "gradient" filter often
helps to improve data compression ratios, but may slow down the server performance. Please note
that this filter is never used when a client enables JPEG compression in the Tight encoding.

-desktop name
Set VNC desktop name ("x11" by default).

-alwaysshared
Always treat new clients as shared, never disconnect existing client on a new client connection.

-nevershared
Never treat new clients as shared, do not allow several simultaneous client connections.

-dontdisconnect
Don't disconnect existing clients when a new non-shared connection comes in, refuse new connection
instead.

-viewonly
Don't accept keboard and pointer events from clients. All clients will be able to see the desktop
but won't be able to control it.

-localhost
Only allow loopback connections from localhost. This option is useful in conjunction with SSH
tunneling.

-interface ipaddr
Listen for client connections only on the network interface with given ipaddr.

-inetd Xvnc is launched by inetd. This option causes Xvnc to redirect network input/output to
stdin/stdout.

-compatiblekbd
Set META and ALT keys to the same X modifier flag, as in the original version of Xvnc by AT&T labs
(TightVNC-specific).

BUGS

       There  are  many  security  problems in current Xvnc implementation. It's recommended to restrict network
       access to Xvnc servers from untrusted network addresses. Probably, the best way to secure Xvnc server  is
       to  allow  only  loopback  connections  from  the  server  machine (the -localhost option) and to use SSH
       tunneling  for  remote   access   to   the   Xvnc   server.   For   details   on   SSH   tunneling,   see
       <URL:http://www.cl.cam.ac.uk/Research/DTG/attarchive/vnc/sshvnc.html> .

AUTHORS