x0vncserver - TigerVNC Server for X displays
is a TigerVNC Server which makes any X display remotely
accessible via VNC, TigerVNC or compatible viewers. Unlike Xvnc(1)
does not create a virtual display. Instead, it just shares an existing X
server (typically, that one connected to the physical screen).
XDamage will be used if the existing X server supports it. Otherwise
will fall back to polling the screen for changes.
interprets the command line as a list of parameters with
optional values. Running x0vncserver -h
will show a list of all valid
parameters with short descriptions. All parameters are optional, but normally
you would have to use the PasswordFile
parameter (see its description
There are several forms of specifying parameters in the command line (here we
use ` SomeParameter
' as an example parameter name):
- Enable the parameter, turn the feature on. This form can be used with
parameters that simply enable or disable some feature.
- Disable the parameter, turn the feature off.
- Assign the specified value to the parameter. The leading dash can
be omitted, or it can be doubled if desired (like in GNU-style long
Parameter names are case-insensitive, their order in the command line can be
- -display display
- The X display name. If not specified, it defaults to the value of the
DISPLAY environment variable.
- -rfbport port
- Specifies the TCP port on which x0vncserver listens for connections from
viewers (the protocol used in VNC is called RFB - "remote
framebuffer"). The default port is 5900.
- Use IPv4 for incoming and outgoing connections. Default is on.
- Use IPv6 for incoming and outgoing connections. Default is on.
- -rfbunixpath path
- Specifies the path of a Unix domain socket on which x0vncserver listens
for connections from viewers, instead of listening on a TCP port.
- -rfbunixmode mode
- Specifies the mode of the Unix domain socket. The default is 0600.
- -Log logname:dest:level
- Configures the debug log settings. dest can currently be
stderr, stdout or syslog, 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
- -HostsFile filename
- This parameter allows to specify a file name with IP access control rules.
The file should include one rule per line, and the rule format is one of
the following: + address/prefix (accept connections from the
specified address group), - address/prefix (reject
connections) or ? address/prefix (query the local user). The
first rule matching the IP address determines the action to be performed.
Rules that include only an action sign (+, - or ?) will match any IP
address. Prefix is optional and is specified as a number of bits
(e.g. /24). Default is to accept connections from any IP address.
- -SecurityTypes sec-types
- Specify which security scheme to use for incoming connections. Valid
values are a comma separated list of None, VncAuth,
Plain, TLSNone, TLSVnc, TLSPlain,
X509None, X509Vnc and X509Plain. Default is
- -rfbauth passwd-file, -PasswordFile passwd-file
- Password file for VNC authentication. There is no default, you should
specify the password file explicitly. Password file should be created with
the vncpasswd(1) utility. The file is accessed each time a
connection comes in, so it can be changed on the fly.
- -Password password
- Obfuscated binary encoding of the password which clients must supply to
access the server. Using this parameter is insecure, use
PasswordFile parameter instead.
- -PlainUsers user-list
- A comma separated list of user names that are allowed to authenticate via
any of the "Plain" security types (Plain, TLSPlain, etc.).
Specify * to allow any user to authenticate using this security
type. Default is to deny all users.
- -pam_service name, -PAMService name
- PAM service name to use when authentication users using any of the
"Plain" security types. Default is vnc.
- -X509Cert path
- Path to a X509 certificate in PEM format to be used for all X509 based
security types (X509None, X509Vnc, etc.).
- -X509Key path
- Private key counter part to the certificate given in X509Cert. Must
also be in PEM format.
- -GnuTLSPriority priority
- GnuTLS priority string that controls the TLS session’s handshake
algorithms. See the GnuTLS manual for possible values. Default is
- -BlacklistThreshold count
- The number of unauthenticated connection attempts allowed from any
individual host before that host is black-listed. Default is 5.
- -BlacklistTimeout seconds
- The initial timeout applied when a host is first black-listed. The host
cannot re-attempt a connection until the timeout expires. Default is
- Prompts the user of the desktop to explicitly accept or reject incoming
connections. Default is off.
- -QueryConnectTimeout seconds
- Number of seconds to show the Accept Connection dialog before rejecting
the connection. Default is 10.
- Always treat incoming connections as shared, regardless of the
client-specified setting. Default is off.
- Never treat incoming connections as shared, regardless of the
client-specified setting. Default is off.
- Disconnect existing clients if an incoming connection is non-shared.
Default is on. If DisconnectClients is false, then a new non-shared
connection will be refused while there is a client active. When combined
with NeverShared this means only one client is allowed at a
- Accept key press and release events from clients. Default is on.
- Accept pointer press and release events from clients. Default is on.
- -RemapKeys mapping
- Sets up a keyboard mapping. mapping is a comma-separated string of
character mappings, each of the form char->char, or
char<>char, where char is a hexadecimal keysym.
For example, to exchange the " and @ symbols you would specify the
- Send keyboard events straight through and avoid mapping them to the
current keyboard layout. This effectively makes the keyboard behave
according to the layout configured on the server instead of the layout
configured on the client. Default is off.
- Always use protocol version 3.3 for backwards compatibility with
badly-behaved clients. Default is off.
- -Geometry geometry
- This option specifies the screen area that will be shown to VNC clients.
The format is
widthxheight+xoffset+yoffset , where
`+' signs can be replaced with `-' signs to specify offsets from the right
and/or from the bottom of the screen. Offsets are optional, +0+0 is
assumed by default (top left corner). If the argument is empty, full
screen is shown to VNC clients (this is the default).
- -MaxProcessorUsage percent
- Maximum percentage of CPU time to be consumed when polling the screen.
Default is 35.
- -PollingCycle milliseconds
- Milliseconds per one polling cycle. Actual interval may be dynamically
adjusted to satisfy MaxProcessorUsage setting. Default is 30.
- -FrameRate fps
- The maximum number of updates per second sent to each client. If the
screen updates any faster then those changes will be aggregated and sent
in a single update to the client. Note that this only controls the maximum
rate and a client may get a lower rate when resources are limited. Default
- -CompareFB mode
- Perform pixel comparison on framebuffer to reduce unnecessary updates. Can
be either 0 (off), 1 (always) or 2 (auto). Default is
- Use MIT-SHM extension if available. Using that extension accelerates
reading the screen. Default is on.
- -ZlibLevel level
- Zlib compression level for ZRLE encoding (it does not affect Tight
encoding). Acceptable values are between 0 and 9. Default is to use the
standard compression level provided by the zlib(3) compression
- Use improved compression algorithm for Hextile encoding which achieves
better compression ratios by the cost of using slightly more CPU time.
Default is on.
- -IdleTimeout seconds
- The number of seconds after which an idle VNC connection will be dropped.
Default is 0, which means that idle connections will never be
- -MaxDisconnectionTime seconds
- Terminate when no client has been connected for N seconds. Default
- -MaxConnectionTime seconds
- Terminate when a client has been connected for N seconds. Default
- -MaxIdleTime seconds
- Terminate after N seconds of user inactivity. Default is 0.
- -ClientWaitTimeMillis time
- Time in milliseconds to wait for a viewer which is blocking the server.
This is necessary because the server is single-threaded and sometimes
blocks until the viewer has finished sending or receiving a message - note
that this does not mean an update will be aborted after this time. Default
is 20000 (20 seconds).
- -SendCutText -MaxCutText Currently unused.
Constantin Kaplinsky 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