VNC Server Free Edition 4.1 for Windows
o Upgrading from VNC Free Edition 4.0
o User-Mode Operation
o Service-Mode Operation
o The Connections Options
o The Authentication Options
o The Inputs Options
o The Sharing Options
o The Desktop Options
o The Capture Method Options
o The Legacy & VNC 3.3 Import Options
o Other Options
o Windows 3.11 / Windows NT 3.51 / Windows 95
o Windows 98 / Windows Me
o Windows XP and Windows 2003 Server
System hardware meeting OS requirements
Windows-compatible graphics card
Windows-compatible network card
TCP/IP v4 network stack
or Windows Me1
or Windows NT 4.0 Workstation / Server2
or Windows 2000 Professional / Server
or Windows XP Professional / Home3
or Windows 2003 Server3
1. These platforms do not support secure settings
2. Service Pack 3, 4, 5 or 6a is required on these platforms
3. If Fast User Switching or Remote Desktop are used, then VNC Server will connect
session zero to the console in order to allow it to be accessed. Other sessions cannot be
accessed by VNC Server Free Edition 4.1.
VNC Server Free Edition for Windows is installed as an optional component of the setup
package. If VNC Server has been installed then a number of icons will be created for it under the
Start Menu, at the location specified during installation (usually RealVNC).
VNC Server for Windows is designed to run either in User-Mode, as a personal per-user server,
or in Service-Mode, as a system service available whether or not there is a user logged in.
The logged-on user can also choose to run their own personal User-Mode server alongside an
existing Service-Mode server installed on the machine, provided that the two servers are
configured to operate on different network port numbers.
Upgrading from VNC Free Edition 4.0
VNC Server Free Edition 4.1 retains full compatibility with VNC Server Free Edition 4.0, with
respect both to command-line parameters and to registry configuration options. When installed
on a system that has already been fully configured for VNC Server Free Edition 4.0, VNC Server
Free Edition 4.1 will use the existing settings, without the need for reconfiguration.
Using VNC Server in User-Mode
If you are just trying out VNC, or wish to provide access to your desktop infrequently for support
or collaboration purposes, then you may find it best to run VNC Server in User-Mode.
During the installation, leave the tickboxes which refer to the VNC Server System Service
unticked, to prevent VNC Server being installed in Service-Mode on your system.
When you want to use VNC Server, go to the VNC Server (User-Mode) program group
(usually found under RealVNC in the Start Menu), and click on Run VNC Server. The VNC
Server icon will appear in the system tray, to indicate that VNC Server is running.
At this point, you probably want to configure your personal VNC Server settings for User-Mode.
Right-click on the tray icon and select Options..., change the settings you want and click Apply
or Ok. Note that you must at least configure the Authentication tab, otherwise you won't be able
to connect in to your server - this is deliberately the case, to avoid accidentally opening up your
computer to attacks.
When you are finished with VNC Server, simply select Close VNC Server from the tray icon's
Using VNC Server in Service-Mode
If you intend to use VNC to provide remote access to a computer, you will probably prefer to
install VNC Server in Service-Mode. In Service-Mode, VNC Server can allow remote
connections even while the computer is locked or logged off. The server is configured once,
rather than per-user, and the settings are secured if the host platform supports it.
During the installation, tick each of the boxes which refer to the VNC Server System Service.
This will cause the installer to present the VNC Server Options dialog, and to register and run the
VNC Server Service.
Note that you must at least configure the Authentication tab, otherwise you won't be able to
connect in to your server - this is deliberately the case, to avoid accidentally opening up your
computer to attacks.
At this point, your VNC Server is running and you should be able to connect to it from a
connected computer using VNC Viewer.
If you need to reconfigure or stop your Service-Mode server, you will find links in the VNC
Server (Service-Mode) program group of the Start Menu to achieve this. The VNC Server
Properties dialog can also be accessed by right clicking on the VNC Server (Service-Mode)
tray icon and selecting the Options... menu item.
Configuring VNC Server
VNC Server provides a number of options allowing its behaviour to be tailored to your needs.
These are usually configured via the Options... dialog, although they can also be specified
directly on the command-line of the WinVNC4 executable if required.
The Options... dialog consists of a number of pages of options, grouped according to their
function. The following documentation describes each option and the equivalent command-line
When the Ok or Apply buttons of the Options... dialog are pressed, any changed settings are
saved to the registry. Unless otherwise specified, changed settings take effect immediately.
Accept connections on port
If this option is ticked and the port number is non zero then VNC Server accepts
incoming connection requests from clients on a particular TCP port. The standard VNC
Display numbers, 0-99, correspond to TCP ports 5900-5999. VNC Server will accept
connections on port number 5900 by default, which equates to VNC display number 0
(zero). The port number for VNC Server to use can be set to any other available port
number, even ones outside the 5900-5999 range.
Disconnect idle clients after
An idle client is one which has transmitted no keyboard or pointer events for more than a
certain length of time. The VNC Server can be configured with a threshold, expressed in
seconds, after which idle clients will be disconnected to conserve resources. If the
threshold specified is zero seconds then connections will never timeout. The default idle
timeout is one hour.
Note that pointer and keyboard events received from clients will prevent their connection
timing out even if the VNC Server is configured to otherwise ignore those events (see
Serve Java viewer via HTTP on port
If this option is ticked and the port number specified is non-zero then VNC Server will
accept incoming HTTP requests, allowing the Java VNC Viewer to be downloaded by a
Java-aware web browser. The Options... dialog will attempt to adjust the HTTP port to
match changes made to the VNC port number.
Note that the HTTP port number cannot be set to the same value as that used for
incoming VNC connections.
Only accept connections from the local machine
The LocalHost option tells VNC Server to only accept incoming connections from
Viewers running on the local host computer. This is only normally used when
connections are to tunnelled through a custom transport (e.g. serial line, custom wireless,
etc) and will therefore appear to the TCP stack to originate from the local host. If VNC
Server is configured to accept connections only via local loopback then the Hosts option
VNC Server can filter incoming connection attempts based upon the apparent IP
addresses of their originators. Which IP addresses are allowed to connect and which are
not is determined by the Hosts pattern. The pattern consists of a comma-separated list of
IP address specifications, prefixed by an action. Each specification starts with an action,
gives an IP address, and a subnet-style mask. The first specification to match the address
of the new connection determines the action that will performed.
Available actions are:
+: Accept the connection
?: Query the local user to accept the connection.
See also the QueryConnect Authentication option.
-: Reject the connection.
The pattern given above allows the computer with address 192.168.0.1 to connect, as
well as any computer in the 192.168.1 subnet. All other connections are rejected by the
- term, which is actually redundant in this case - a connection will always be rejected if it
doesn't match anything in the Hosts pattern.
Note that IP addresses and masks are specified in Type-A (xxx.yyyyyyyyy), Type-B
(xxx.yyy.zzzzzz) or Type-C (xxx.yyy.zzz.www) form. The specification 192.168 will
therefore be interpreted as 184.108.40.206 rather than 192.168.0.0 as one might expect.
The Hosts pattern can be edited more easily through the Access Control interface, which
allows IP address specifications to be edited individually and moved up (to match first) or
down (to match last) the list.
The Authentication page allows you to configure the required mode of authentication and level
of security of VNC connections. VNC Server Free Edition for Windows supports
unauthenticated connections and classic VNC Password Authentication.
If your VNC Server is operating in a protected environment, such as a secure LAN or
firewall-protected network, then you may wish to configure VNC Server to accept
connections without requiring a username or password to be specified.
We advise extreme caution when disabling authentication. Do not disable it unless
you are absolutely sure that the host network is completely secure.
VNC Password Authentication
VNC Password Authentication allows a single password of up to 8 characters to be
stored by VNC Server, which remote users must supply when prompted in order to
The password to use can be configured by selecting Configure and typing the new
password twice. On platforms which support it, the password (and all other configuration
options) are protected using native operating system security methods, so that the
password cannot be read or tampered with by other users.
NT Logon Authentication
NT Logon Authentication is not available in VNC Free Edition.
Encryption: Always Off
Encryption is not available in VNC Free Edition.
Prompt local user to accept connections
By default, VNC Server allows Viewers to connect as long as the correct username and
password are supplied. QueryConnect allows an extra level of protection to be applied,
requiring a local user to explicitly accept incoming connections.
When QueryConnect is enabled, incoming connections are first authenticated in the
normal way. If the user authenticates successfully then a dialog is presented on the
server's desktop, displaying the IP address and username of the incoming connection, and
requiring a local user to accept the connection.
If the user does not accept the connection within a specified timeout then it is rejected. If
an incoming connection requiring acceptance by the local user is received while an
earlier connection is being queried then the second connection is automatically rejected,
for security reasons.
Connections from specific hosts or subnets can be configured to be queried via the Hosts
Only prompt when there is a user logged on
This option affects the behaviour of the QueryConnect option, if enabled. If this option is
set then the local user will only be prompted to accept the incoming connection if they
are logged in. If this option is not set then the local user will always be prompted,
regardless of whether or not they are logged in.
Note that it is not possible to reliably detect whether or not a user is logged in on some
older Windows platforms. On these platforms, this option will err on the side of security
and always prompt the local user.
If QueryConnect is enabled then the Query Connection dialog will be displayed by
default for ten seconds before automatically rejecting the connection. The timeout value
can be modified by setting QueryConnectTimeout accordingly.
Accept pointer events from clients
If this option is unticked then incoming pointer movements from all clients will be
ignored, preventing any remote VNC Viewer from affecting the pointer of the VNC
Server's desktop. This can be used to configure a server to become effectively view-only.
Note that a client will still be deemed active for the purposes of the IdleTimeout setting if
it is sending pointer events to the server, whether or not they are accepted.
Accept keyboard events from clients
If this option is unticked then incoming keystrokes from all clients will be ignored,
preventing any remote VNC Viewer from typing into the VNC Server's desktop. This can
be used to configure a server to become effectively view-only.
Note that a client will still be deemed active for the purposes of the IdleTimeout setting if
it is sending keyboard events to the server, whether or not they are accepted.
Accept clipboard updates from clients
If this option is unticked then incoming clipboard updates will be ignored from all clients.
This option should be used when making a VNC Server effectively view-only, but may
also prove useful to prevent clipboard changes made by clients from overriding the VNC
Server's local clipboard when this would be undesirable or confusing.
Send clipboard updates to clients
This option, if unticked, prevents the VNC Server from informing clients of changes to
its local clipboard contents. This can be useful when untrusted clients are to be allowed to
connect to the VNC Server, since it prevents any private data being accidentally leaked
via the clipboard.
Allow input events to affect the screen-saver
This option determines whether keyboard and mouse events received from VNC Viewers
can cause the screen-saver to be hidden. This option is actually a system-wide setting and
is not implemented by VNC Server itself, so there is no equivalent command-line option.
Some older Win32 platforms do not support this option. It is recommended that this
check-box be ticked, so that the screen-saver can be disabled by VNC Viewer input.
Disable local inputs while server is in use
The mouse and keyboard physically attached to the server computer can be disabled for
the duration of a remote connection, preventing local users from interacting with the
Always treat new connections as shared
If this option is set then all incoming connections will be treated as shared, and thus not
disconnect any existing connections, regardless of whether the connecting VNC Viewer
requested that the connection be shared.
Never treat new connections as shared
If this option is set then all incoming connections will be treated as non-shared. VNC
Server will therefore either disconnect any existing connections, or refuse the incoming
connection, depending on whether non-shared connections are configured to replace
existing ones (see below).
Use client's preferred sharing setting
When connecting, VNC Viewer specifies whether the connection should be shared or
non-shared. If this setting is configured then the VNC Viewer's preference will be
Non-shared connections replace existing ones
If an incoming connection is to be shared (either by choice or because AlwaysShared is
set) then existing connections remain active. If a connection is non-shared (either by
choice or because NeverShared is set) then either the new connection must be rejected, or
existing clients disconnected.
If this setting is configured then existing clients will be disconnected when a new non-
shared connection is made. Otherwise, they will remain, and the new connection will fail.
Decorations such as wallpaper or font smoothing effects can make it harder for VNC Server to
compress graphical data for trasmission to viewers. For viewers connected over slower networks,
this can significantly degrade the apparent performance of the server. VNC Server can therefore
simplify the desktop in several ways, to improve performance.
This option causes VNC Server to remove any standard wallpaper bitmap that is set, as
well as to disable Active Desktop components.
Remove background pattern
This option causes VNC Server to set the desktop background to a plain pattern while
conenctions are active.
Disable user interface effects
This option causes VNC Server to disable desktop decorations such as font smoothing,
window titlebar shading, menu animation, and so on.
When last client disconnects
These options are used to ensure that if VNC connections to a server are closed because of a
network error, idle timeout, or even deliberately, then the computer will be left in as secure a
state as possible. On Windows 2000 and above, it is possible for VNC Server to lock the
workstation, leaving the current user logged in but requiring that their password be re-entered in
order to access their programs or data. Alternatively, VNC Server can completely logoff the
current user when there are no more VNC viewers connected, closing any running programs and
leaving the workstation ready for another user to log in.
This option tells VNC Server not to perform any action.
This option causes VNC Server to lock the workstation when the last VNC viewer
Note that this option is not available on Windows 95/98/Me and Windows NT 4.
This option causes the current user to be logged off when the last VNC viewer
VNC Server is designed to support a variety of techniques for tracking changes to the local
desktop. This release supports basic polling of the screen for changes, as well as the classic VNC
Poll for changes to the desktop
If this option is selected then VNC Server will poll strips of the screen for changes. The
polling mechanism attempts to minimize the load on the server computer while delivering
a reasonable level of responsiveness.
Use VNC Hooks to track changes
This option tells VNC Server to use the classic VNC Hooks technique to track graphical
updates. This scheme is more efficient than continuous polling but relies on certain
properties of Windows applications and so can "miss" updates in some situations. VNC
Hooks will also poll the screen infrequently to catch any missed updates.
Poll console windows for updates
The VNC Hooks hooking technique cannot track console windows because of limitations
in the operating system. Instead, console windows may be polled for changes. If this
option is set then VNC Server will track the visible parts of console windows and poll
those areas for changes.
Use VNC Mirror driver to track changes
The VNC Mirror driver is not supported by VNC Free Edition.
Capture alpha-blended windows
This option selects between two screen capture methods. If UseCaptureBlt is false then
the faster of the two methods is used, which may in some cases cause alpha-blended
windows and tool-tips not to be visible remotely. If UseCaptureBlt is true then these
windows will be visible remotely but the VNC Server overhead will be increased.
Note that one aspect of the extra server overhead is that the local cursor will flicker if
UserCaptureBlt is enabled.
Import VNC Free Edition 3.3 Settings
If you have configured WinVNC 3.3 on a machine then you can automatically have VNC
Server 4 configure itself to match your existing 3.3 settings as closely as possible. VNC
Server 4 will warn you when it cannot match existing settings completely, or if they are
no longer relevant.
If you choose to import settings to configure a User-Mode VNC Server then VNC Server
will attempt to import your personal WinVNC 3.3 settings. If you choose to import
settings to configure a Service-Mode VNC Server then the WinVNC 3.3 Default settings
on the local machine will be used.
Note that you must separately uninstall the WinVNC 3.3 service if you import the
settings into VNC Server 4, or configure VNC Server 4 to operate on a different port
Only use protocol version 3.3
VNC Server 4 supports both the original VNC version 3.3 protocol, and the new VNC
protocol version 3.8. Some third-party VNC software use non-standard version numbers
which may cause incompatibility issues. VNC Server 4 can therefore be configured only
to use the original VNC protocol version, ensuring compatibility even with non-standard
Note that this option applies to all VNC connections and reduces the functionality
available to connecting VNC Viewers.
In addition to the settings described above, the VNC server supports several advanced options.
These options can be set on the command-line or by adding an appropriate value to the Windows
registry. For User-Mode servers, this value should be added under the
HKEY_CURRENT_USER\Software\RealVNC\WinVNC4 key; for Service-Mode servers, the
appropriate key is HKEY_LOCAL_MACHINE\Software\RealVNC\WinVNC4.
Disable or enable the Close menu item in the system tray menu. Note that this does not
prevent users from shutting down the WinVNC4 process using the Task Manager or the
Service Control Manager if they have sufficient access rights to do so.
Disable or enable the Options... menu item in the system tray menu. Note that this does
not prevent users from changing the settings in the Windows registry if they have
sufficient access rights to do so.
The display device to remote, or empty to remote all displays. The format of display is
\\.\<device>. For example, \\.\display1.
Keyboard remapping. mappingis 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 following:
For a full list of options, run winvnc4 -help.
Windows 3.11 / Windows NT 3.51 / Windows 95
VNC Free Edition is not designed to operate on Windows 3.11 or older, Windows NT 3.51 or
Windows 98 / Windows Me
VNC Free Edition is designed to operate on both Windows 98 and Windows Me. Because these
platforms are inherently insecure, it is not possible to protect the VNC Server settings from
Windows XP and Windows 2000 Server
VNC Server is only capable of providing access to session zero. If a different user session is the
active console session whena VNC viewer connects, VNC Server will attempt to make session
zero the console session.
VNC Viewer Free Edition 4.1 for Windows
Connecting to a VNC Server
o Connecting using existing .vnc files
o User Authentication
Configuring VNC Viewer
o Color / Encoding Options
o Input Options
o Miscellaneous Options
o Load / Save Options
o Other Settings
The F8 Menu
o The F8 Menu Functions
VNC Viewer Free Edition for Windows is supplied as a component of the VNC Free Edition
installation program. If the viewer has been installed in this way then it will be accessible via the
Start Menu group created during the installation process (usually RealVNC/VNC Viewer 4).
The viewer executable may also be downloaded, either directly or Zipped. VNC Viewer for
Windows is designed to run stand-alone, without requiring any other packages to be installed
Connecting to a VNC Server
If installed by the WinVNC setup package then VNC Viewer is accessible from the Start Menu.
If downloaded directly, the VNC Viewer can be run either by double-clicking on the program
icon, or from the command-line.
The VNC Viewer will present the Connection Details dialog, allowing the IP address or name
of the target VNC Server to be specified.
If the VNC server's Display Number is non-zero then the display number can be specified by
adding a colon to the server's IP address or name, followed by the display number:
If the VNC server is using a non-standard port number to accept connections then this is
specified by adding two colons to the server's address or name, followed by the port number:
Encryption is not currently supported by VNC Free Edition.
Once you have selected the VNC server to connect to, you can simply click OK or press return
to attempt to connect to it. If your connection attempt succeeds then the server's details will be
added to the Connection Details drop-down menu, to save you typing next time.
Alternatively, you can select the Options... button, to override the default connection
configuration, before you connect. See the Configuring VNC Viewer documentation for more
Connecting using .vnc files
VNC Viewer Free Edition supports loading and saving of .vnc files, containing a set of
connection options. VNC Viewer 4 can load .vnc files saved by itself, or by VNC Viewer 3.
To use a connection options file from the command-line, simply run VNC Viewer with the -
config command-line option, followed by the .vnc filename.
If you have installed VNC Viewer using the WinVNC setup package then .vnc files will have
been automatically registered, so that you can simply double-click on one to have VNC Viewer
If you have not installed VNC Viewer using the WinVNC setup package
then you can instead drag .vnc files and drop them on the VNC Viewer executable icon in order
to launch them.
Alternatively, if you have had VNC Viewer 3 installed and have used .vnc files with it then it is
likely that VNC Viewer 3 is already registered with Windows as the application responsible for
.vnc files. VNC Viewer 4 supports the old /config form of the -config command-line option,
so you should find that you can simply replace your old VNC Viewer with the new one and have
.vnc files continue to work.
VNC Viewer Free Edition can be used to connect to servers configured for No Authentication or
VNC Password Authentication. If VNC Password Authentication is configured then you will be
prompted to enter the password. VNC Free Edition does not currently support usernames.
Configuring VNC Viewer
VNC Viewer provides a number of options allowing its behaviour to be tailored to your needs.
These are configured in one of three ways listed below.
Changing the Default Options
VNC Viewer allows a set of options to be saved per-user, which will be used as the defaults for
all connections that user makes to VNC Servers. These Default Options can be overridden from
the Connection Details dialog before making a connection, or during a connection via the F8
Menu, or by specifying the options to override on the VNC Viewer command-line.
While the VNC Viewer is running in listening mode, it will place an icon in the system tray.
Right-clicking on this icon will cause a menu to be displayed, through which the Default
Options may be accessed. The Default Options are saved on a per-user basis, and are used for
all subsequent VNC connections.
Changing the Options for a New/Current Connection
The Options dialog can be accessed from the Connection Details dialog when making a new
VNC connection, or from the F8 Menu of an active connection. In either case, the dialog can be
used to override any settings configured through the Default Options dialog.
Specifying Command-Line Options
VNC Viewer allows any option to be specified on the command-line when it is launched.
Options specified on the command-line override those specified in the Default Options dialog.
However, options configured on the command-line can be changed once a connection has been
made using the Connection Options dialog.
The Options dialog consists of a number of pages of options, grouped according to their
function. The following documentation describes each option and the equivalent command-line
Color / Encoding
The Auto select check-box controls whether or not VNC Viewer should attempt to
automatically gauge the speed of the network connection to the VNC Server and adjust
its behaviour accordingly. If selected, the viewer will take control of the graphical
compression scheme used, and will only request full color updates if the network appears
fast enough to support them. If not selected, then the user must select suitable encoding
and format options manually.
The ZRLE, Hextile and Raw radio buttons allow the preferred graphical encoding used
by VNC Viewer to be controlled by the user. The available encodings are arranged in
order of increasing bandwidth requirements and decreasing processing requirements, so
that ZRLE is most effective on slow networks such as dial-ups, while Raw is often most
effective on fast LANs. The preferred encoding is determined automatically by VNC
Viewer if the Auto select checkbox is ticked.
The Colour level box controls whether VNC Viewer should request as many colors as it
and the server can handle, or one of a predefined set of lower-color, less bandwidth-
Full (all available colors)
If Full Colour mode is selected then VNC Viewer will attempt to render colors as
accurately as possible. Otherwise, a reduced number of colors will be used, to limit the
required network bandwidth. The reduced color mode to use is determined by the
Medium (256 colors)
Low (64 colors)
Very Low (8 colors)
If Full Colour mode is not active then VNC Viewer will instead request one of a set of
preset lower color modes. These modes range from Medium color, which requests 8bpp
palettized pixel data from the server, to Very Low color, which requests pixel data in
3bpp true-color format, causing the entire desktop to be rendered in lurid primary colors.
Note that if the Auto select check-box is ticked then the automatic pixel format selection
routines may override the user's selection and cause the connection to revert to Full
Colour mode. However, it will not automatically select between the low color options.
Send pointer events to server
By default, any pointer actions within the VNC Viewer window will be sent to the VNC
server. If this checkbox is unticked then pointer events will no longer be sent, allowing
VNC Viewer to operate in a view-only mode.
Send keyboard events to server
By default, any key presses within the VNC Viewer window will be sent to the VNC
server. If this checkbox is unticked then key events will no longer be sent, allowing VNC
Viewer to operate in a view-only mode.
Send clipboard changes to server
By default, any text copied to the clipboard will be sent to the VNC server, so that the
remote and local clipboards are synchronised. If this checkbox is unticked then clipboard
data will no longer be sent, ensuring that clipboard actions made at the server are not
affected by the viewer, and that sensitive data in the local clipboard cannot be leaked to
Accept clipboard changes from server
By default, any text copied to the remote clipboard will be sent by the VNC Server to the
VNC Viewer. If this checkbox is unticked then clipboard data sent by the server will be
ignored, ensuring that clipboard actions made at the server cannot affect the local
Enable 3-button mouse emulation
If this checkbox is ticked then VNC Viewer will translate simultaneous left and right
mouse-button press events as a middle button press. This is normally used when
accessing applications for systems such as X Windows, which assume the availability of
a middle mouse button, from older Windows systems that don't have one.
This option allows the key used to summon the "F8 Menu" to be changed to one of the
function keys F1 to F12, or to be disabled entirely by setting MenuKey to be empty.
Pass special keys directly to server
If this checkbox is ticked (DisableWinKeys is true) then special key sequences such as
the Windows keys, Application key or Alt-Tab will be passed to the VNC Server rather
than being interpreted locally. The special Secure Access Sequence Ctrl-Alt-Del is
always processed by the viewer computer, and not passed to the server.
Note that if you run a full-screen VNC Viewer, with MenuKey disabled and
DisableWinKeys set, then you will find it rather hard to get out of the viewer, back to
your local applications! In this case, you will probably need to use Ctrl-Alt-Del to close
VNC Viewer, or to switch to another application if possible.
Shared connection (do not disconnect other viewers)
When connecting to a VNC Server, VNC Viewer can request that all other connected
viewers are disconnected before the connection continues. If Shared connection is ticked
then VNC Viewer will not request that other viewers be disconnected. Note that the
server may choose to ignore or refuse VNC Viewer's request. Note that this option is only
available when configuring the Default Options or when configuring a new connection,
not when the connection is already active.
If the Full-screen mode checkbox is ticked then VNC Viewer will attempt to take over
the entire local display in order to show the remote desktop. The full-screen setting can
be set as a default, used for new connections, and changed once a connection is active.
The F8 Menu also provides a shortcut to toggle full-screen mode.
Render cursor locally
VNC Viewer 4 supports rendering of the VNC Server's cursor locally, by the viewer.
This means that the cursor responds more quickly to mouse movemements and makes
VNC connections over slow networks appear faster. Over faster networks, or for personal
preference, this local rendering may be disabled by unticking the Render cursor locally
Allow dynamic desktop resizing
VNC Viewer 4 supports dynamic resizing of the VNC Server desktop. If dynamic
resizing is not supported by both viewer and server then changes to the dimensions of the
remote desktop may cause the VNC connection to be closed. Dynamic desktop resizing
can be disabled if it causes problems on your system.
Only use protocol version 3.3
VNC Viewer 4 supports both the original VNC version 3.3 protocol, and the new VNC
protocol version 3.7. Some third-party VNC software use non-standard version numbers
which may cause incompatibility issues. VNC Viewer 4 can therefore be configured to
use only the original VNC protocol version 3.3, ensuring compatibility even with non-
standard VNC Servers. Note that this option may be set as a Default Option, or when
making a new connection, but cannot be changed once a connection is active.
Beep when requested to by the server
By default, VNC Viewer will cause a sound to be produced whenever a bell event is
received from the server. This option allows bell events to be ignored by VNC Viewer.
Offer to automatically reconnect
When an error occurs that causes the VNC connection to be closed, VNC Viewer can
offer to reconnect to the server, using the same username and password. This option
applies only to connections made from viewer to server, and not to reverse connections.
Load / Save
VNC Viewer stores a set of preferred defaults for all new connections in the user's registry.
Special purpose settings, or settings specific to particular hosts can be maintained by using VNC
Configuration (.vnc) files.
If the VNC session was started by loading settings from a VNC Configuration file then
the original settings are reloaded from that file.
If the VNC session was started by loading settings from a VNC Configuration file then
the current settings are saved back to that file.
Presents the standard File Save dialog, allowing a target VNC Configuration filename to
be specified. The current settings will then be saved to the specified file.
Reloads the default VNC Viewer settings from the registry.
Saves the current settings to the registry as the defaults for all new VNC Viewer sessions.
In addition to the settings described above, the VNC viewer supports several advanced options.
These options can be set either on the command-line or by adding an appropriate value to the
Windows registry under the HKEY_CURRENT_USER\Software\RealVNC\VNCViewer4 key. For a
full list of options, run vncviewer -help.
Using F8 Menu
The so-called F8 Menu provides a quick way to access a set of frequently-used VNC Viewer
functions. It is called the F8 Menu because by default it can be accessed simply by pressing the
F8 key in a VNC Viewer window! If the MenuKey option has been used to specify a different
key then we still call it the F8 Menu, to keep things simple...
The F8 Menu can also be accessed by right-clicking on the titlebar of a VNC Viewer window, or
by left-clicking on the System Menu button in the top left of the VNC Viewer window's titlebar.
Clicking anywhere outside the F8 Menu will cause it to go away again.
F8 Menu Functions
The F8 Menu provides the same set of available functions as the VNC Viewer window's normal
System Menu, namely those allowing the window to be minimized, maximized, moved or
Additionally, some VNC-specific actions are available:
The Full screen menu item allows full-screen mode to be toggled on or off directly,
without having to use the Options dialog. See the description of the Full screen setting in
the Options page for more information.
Ctrl and Alt
Toggles the status of the Ctrl or Alt keys, respectively, on the VNC Server. This affects
the interpretation by the server of keypress sent while either or both of these menu items
is activated. For example, if the Alt menu item is selected, then pressing the Tab key in
the VNC Viewer will cause the VNC Server to process an Alt+Tab. This can be useful to
send keypresses that would otherwise be intercepted locally by the operating system.
Because the F8 key is used to access the F8 menu, it will not be sent to the VNC Server
when it is pressed. To send an F8 keypress to the server, you can bring up the F8 Menu
locally and select the Send F8 menu option.
Note that if the MenuKey option has been changed to a different function key then this
menu item will reflect that change. If the MenuKey has been disabled entirely then this
option will not be present.
The Ctrl-Alt-Del key sequence is intercepted by the operating system for use as a Secure
Access Sequence and so cannot be captured by the VNC Viewer for transmission to a
remote server. Instead, you can bring up the F8 Menu and select Send Ctrl-Alt-Del to
achieve the same effect.
Note that on some versions of the operating system, pressing Alt Gr-Del will cause the
Ctrl-Alt-Del sequence to be captured by VNC Viewer without the operating system
intercepting it. This is available primarily on European versions of the operating system.
Note that on all versions tested, pressing Shift-Ctrl-Alt-Del could be used to cause Ctrl-
Alt-Del to be received by a WinVNC Server without having the local operating system
capture the it.
Requests a full screen update from the VNC Server. Use this if you experience any
unexpected visual artifacts.
The New Connection... option causes a new Connection Details dialog to be displayed, so
that a connection can easily be made to another VNC Server.
Note that a VNC Viewer started in this way actually shares the same process as the VNC
Viewer window from which it was started. The VNC Viewer process will not quit until
both windows have been closed. This may affect the behaviour of scripts which launch
This causes the Connection Options dialog to be displayed, allowing the settings for the
current connection to be modified. See the description of VNC Viewer Options for more
The Connection Info dialog displays information about the remote host, pixel format,
line-speed estimate and protocol version. If you don't know what any of this means then
don't worry - it's all safe to ignore! The main use of the Connection Info dialog is to help
in diagnosing any problems you might encounter while using VNC Viewer.
Displays program and version information.
If you have difficulties which are not covered by this document, try reading the FAQ. There are
also some pages to help with troubleshooting.