TigerVNC

Related articles
x11vnc
TurboVNC
TigerVNC
is an implementation of the
Virtual Network Computing
(VNC) protocol. This article focuses on the server functionality.
Installation
Install
the
tigervnc
package.
Running vncserver for virtual (headless) sessions
Initial setup
Note
Linux systems can have as many VNC servers as memory allows, all of which will be running in parallel to each other.
For a quick start, see the steps below.  Users are encouraged to read
vncserver(8)
for the complete list of configuration options.
Create a password using
vncpasswd
which will store the hashed password in
$XDG_CONFIG_HOME/tigervnc/passwd
. Ensure the file's permission is set to
0600
. If creating vncserver access for another user, you must be logged in as that user before running vncpasswd.
Edit
/etc/tigervnc/vncserver.users
to define user mappings.  Each user defined in this file will have a corresponding port on which its session will run.  The number in the file corresponds to a TCP port.  By default, :1 is TCP port 5901 (5900+1).  If another parallel server is needed, a second instance can then run on the next highest, free port, i.e 5902 (5900+2).
Create
$XDG_CONFIG_HOME/tigervnc/config
and at a minimum, define the type of session desired with a line like
session=foo
where foo corresponds to whichever
desktop environment
is to run.  One can see which desktop environments are available on the system by seeing their corresponding
.desktop
files within
/usr/share/xsessions/
. For example:
$XDG_CONFIG_HOME/tigervnc/config
session=lxqt
geometry=1920x1080
localhost
alwaysshared
Note
The previous step requires additional security setup to fully work; see
#Accessing vncserver via SSH tunnels
to complete the setup. For testing purposes, omit this step to allow unsecured connections from outside of localhost.
Starting and stopping tigervnc
Start
an instance of the
vncserver@.service
template and optionally
enable
it to run at boot time/shutdown. Note that the
instance identifier
in this case is the display number (e.g. instance
vncserver@:1.service
for display number
:1
).
Note
Direct calls to
/usr/bin/vncserver
are not supported as they will not establish a proper session scope. The
systemd
service is the only supported method of using TigerVNC. See:
Issue #1096
.
Remove drop-in service files created for earlier versions of TigerVNC before starting
vncserver
. Prior versions required drop-in service files for each display, e.g. for display :1
/etc/systemd/system/vncserver@:1.service
.
vncserver
will fail to start if the old drop-in file is present when started with the new templated service file.
Expose the local display directly
TigerVNC includes
libvnc.so
, which can be seamlessly loaded during X initialization for enhanced performance. To utilize this feature, create the following file and then restart X:
/etc/X11/xorg.conf.d/10-vnc.conf
Section "Module"
Load "vnc"
EndSection

Section "Screen"
Identifier "Screen0"
Option "UserPasswdVerifier" "VncAuth"
Option "PasswordFile" "/root/.vnc/passwd"
EndSection
Running x0vncserver to directly control the local display
tigervnc
also provides
x0vncserver(1)
which allows direct control over a physical X session. After defining a session password using the
vncpasswd
tool, invoke the server like so:
$ x0vncserver -rfbauth $XDG_CONFIG_HOME/tigervnc/passwd
Note
x11vnc
is an alternative VNC server which can also provide direct control of the current X session.
x0vncserver
does not currently support clipboard sharing between the client and the server (even with the help of
autocutsel
). See:
Issue #529
.
With xprofile
A simple way to start
x0vncserver
is adding a line in one of the
xprofile
files such as:
~/.xprofile
...
x0vncserver -rfbauth $XDG_CONFIG_HOME/tigervnc/passwd &
With systemd
With a system service
This option will allow the users to access the current display, including the login screen provided by the display manager.
The service will be relaunched automatically every time an user logs off of their session.
LightDM
is used for the example below, but it should be possible to adapt it to other display managers by modifying the
XAUTHORITY
variable.
/etc/systemd/system/x0vncserver.service
[Unit]
Description=Remote desktop service (VNC) for :0 display
Requires=display-manager.service
After=network-online.target
After=display-manager.service

[Service]
Type=simple
Environment=HOME=/root
Environment=XAUTHORITY=/var/run/lightdm/root/:0
ExecStart=x0vncserver -display :0 -rfbauth $XDG_CONFIG_HOME/tigervnc/passwd
Restart=on-failure
RestartSec=500ms

[Install]
WantedBy=multi-user.target
As this is a system unit,
-rfbauth $XDG_CONFIG_HOME/tigervnc/passwd
refers to
/root/.vnc/passwd
Start/enable
x0vncserver.service
.
With a user service
In order to have a VNC Server running
x0vncserver
, which is the easiest way for most users to quickly have remote access to the current desktop, create a
systemd
unit as follows replacing the user and the options with the desired ones:
~/.config/systemd/user/x0vncserver.service
[Unit]
Description=Remote desktop service (VNC)

[Service]
Type=simple
ExecStartPre=/bin/sh -c 'while ! pgrep -U "$USER" Xorg; do sleep 2; done'
ExecStart=/usr/bin/x0vncserver -rfbauth %h/.vnc/passwd

[Install]
WantedBy=default.target
The
ExecStartPre
line waits for Xorg to be started by
${USER}
.
To login with a specific username and password, replace
ExecStart
by
/usr/bin/x0vncserver -PAMService=login -PlainUsers=${USER} -SecurityTypes=TLSPlain
.
Start/enable
the
x0vncserver.service
user unit
.
Running Xvnc with XDMCP for on demand sessions
One can use
systemd
socket activation in combination with
XDMCP
to automatically spawn VNC servers for each user who attempts to login, so there is no need to set up one server/port per user. This setup uses the display manager to authenticate users and login, so there is no need for VNC passwords. The downside is that users cannot leave a session running on the server and reconnect to it later.
To get this running, first set up
XDMCP
and make sure the display manager is running.
Then create:
/etc/systemd/system/xvnc.socket
[Unit]
Description=XVNC Server

[Socket]
ListenStream=5900
Accept=yes

[Install]
WantedBy=sockets.target
/etc/systemd/system/xvnc@.service
[Unit]
Description=XVNC Per-Connection Daemon

[Service]
ExecStart=-/usr/bin/Xvnc -inetd -query localhost -geometry 1920x1080 -once -SecurityTypes=None
User=nobody
StandardInput=socket
StandardError=syslog
Start/enable
xvnc.socket
. Now, any number of users can get unique desktops by connecting to port 5900.
If the VNC server is exposed to the internet, add the
-localhost
option to
Xvnc
in
xvnc@.service
(note that
-query localhost
and
-localhost
are different switches) and follow
#Accessing vncserver via SSH tunnels
. Since we only select a user after connecting, the VNC server runs as user
nobody
and uses
Xvnc
directly instead of the
vncserver
script, so any options in
$XDG_CONFIG_HOME/tigervnc
are ignored. Optionally,
autostart
vncconfig
so that the clipboard works (
vncconfig
exits immediately in non-VNC sessions). One way is to create:
/etc/X11/xinit/xinitrc.d/99-vncconfig.sh
#!/bin/sh
vncconfig -nowin &
Connecting to vncserver
Warning
The default's TigerVNC security method is not secure. It lacks identity verification and will not prevent man-in-the-middle attack during the connection setup. Take care to understand the security settings of the server and do not connect insecurely to a vncserver outside of a trusted LAN.
Note
By default, TigerVNC uses the
TLSVnc
authentication/encryption method unless specifically instructed via the
SecurityTypes
parameter. With
TLSVnc
, there is standard VNC authentication and traffic is encrypted with GNUTLS but the identity of the server is not verified. TigerVNC supports alternative security schemes such as
X509Vnc
that combines standard VNC authentication with GNUTLS encryption and server identification; this is the recommended mode for a secure connection.
When
SecurityTypes
on the server is set to a non-encrypted option as high-priority (such as
None
,
VncAuth
,
Plain
,
TLSNone
,
TLSPlain
,
X509None
,
X509Plain
), which is ill-advised, then it is not possible to use encryption. When running
vncviewer
, it is safer to explicitly set
SecurityTypes
and not accept any unencrypted traffic. Any other mode is to be used only when
#Accessing vncserver via SSH tunnels
.
Any number of clients can connect to a vncserver.  A simple example is given below where vncserver is running on 10.1.10.2 port 5901, or :1 in shorthand notation:
$ vncviewer 10.1.10.2:1
Passwordless authentication
The
-passwd
switch enables one to specify the location of the server's
$XDG_CONFIG_HOME/tigervnc/passwd
file. This file is expected to be accessible to the user through
SSH
or physical access to the server. In either case, place the file on the client's file system in a safe location, i.e. one in which only the intended user has read access.
$ vncviewer -passwd
/path/to/server-passwd-file
The password can also be provided directly.
Note
The password below is not secured; anyone who can run
ps
on the machine will see it.
$ vncviewer -passwd <(echo MYPASSWORD | vncpasswd -f)
Example GUI-based clients
gtk-vnc
krdc
vinagre
AUR
remmina
virt-viewer
TigerVNC's vncviewer also has a simple GUI when run without any parameters:
$ vncviewer
Accessing vncserver via SSH tunnels
For servers offering SSH connection, an advantage of this method is that it is not necessary to open any other port than the already opened SSH port to the outside, since the VNC traffic is tunneled through the SSH port.
On the server
On the server side,
vncserver
or
x0vncserver
must be run.
When running either one of these, it is recommended to use the
localhost
option in
$XDG_CONFIG_HOME/tigervnc/config
or the
-localhost
switch (for
x0vncserver
) since it allows connections from the localhost only and by analogy, only from users ssh'ed and authenticated on the box. For example:
$XDG_CONFIG_HOME/tigervnc/config
session=lxqt
geometry=1920x1080
localhost
alwaysshared
Make sure to
Start
or
Restart
the
vncserver@.service
, for example (see also
#Initial setup
):
# systemctl start vncserver@:1
or for
x0vncserver
:
$ x0vncserver
-localhost
-SecurityTypes none
On the client
The VNC server has been setup on the remote machine to only accept local connections.
Now, the client must open a secure shell with the remote machine (10.1.10.2 in this example) and create a tunnel from the client port, for instance 9901, to the remote server 5901 port. For more details on this feature, see
OpenSSH#Forwarding other ports
and
ssh(1)
.
$ ssh 10.1.10.2 -L 9901:localhost:5901
Once connected via SSH, leave this shell window open since it is acting as the secured tunnel with the server. Alternatively, directly run SSH in the background using the
-f
option. On the client side, to connect via this encrypted tunnel, point the
vncviewer
to the forwarded client port on the localhost.
$ vncviewer localhost:9901
What happens in practice is that the vncviewer connects locally to port 9901 which is tunneled to the server's localhost port 5901. The connection is established to the right port within the secure shell.
Tip
It is possible, with a one-liner, to keep the port forwarding active during the connection and close it right after:
$ ssh -fL 9901:localhost:5901 10.1.10.2 sleep 10; vncviewer localhost:9901
What it does is that the
-f
switch will make ssh go in the background; it will still be alive executing
sleep 10
. vncviewer is then executed and ssh remains open in the background as long as vncviewer makes use of the tunnel. ssh will close once the tunnel is dropped which is the wanted behavior.
Alternatively, vncviewer's
-via
switch provides a shortcut for the above command:
$ vncviewer -via 10.1.10.2 localhost::5901
(Notice the double colon – vncviewer's syntax is
[host]:[display#]
or
[host]::[port]
.)
Connecting to a vncserver from Android devices over SSH
To connect to a VNC server over SSH using an Android device as a client, consider having the following setup:
SSH running on the server
vncserver running on server (with
-localhost
flag for security)
SSH client on the Android device:
ConnectBot
is a popular choice and will be used in this guide as an example
VNC client on the Android device:
androidVNC
used here
In
ConnectBot
, connect to the desired machine. Tap the options key, select
Port Forwards
and add a port:
Type: Local
Source port: 5901
Destination: 127.0.0.1:5901
In
androidVNC
, connect to the VNC port; this is the local address following the SSH connection:
Password: the vncserver password
Address: 127.0.0.1
Port: 5901
Tips and tricks
Connecting to a macOS system
See
https://help.ubuntu.com/community/AppleRemoteDesktop
. Tested with Remmina.
Recommended security settings
If not
#Accessing vncserver via SSH tunnels
where the identification and the encryption are handled via SSH, it is recommended to use
X509Vnc
, as
TLSVnc
lacks identity verification.
$ vncserver -x509key
/path/to/key.pem
-x509cert
/path/to/cert.pem
-SecurityTypes X509Vnc :1
Issuing x509 certificates is beyond the scope of this guide. However,
Let's Encrypt
provides an easy way to do so. Alternatively, one can issue certificates using
OpenSSL
, share the public key with the client and specify it with the
-X509CA
parameter. An example is given below the server is running on 10.1.10.2:
$ vncviewer 10.1.10.2 -X509CA
/path/to/cert.pem
Toggling full-screen
This can be done through vnc client's menu. By default, vnc client's mkey is
Ctrl+Alt+m
.
Workaround for mouse back and forward buttons not working
The VNC protocol currently only uses 7 mouse buttons (left, middle, right, scroll up, scroll down, scroll left, scroll right) which means if the mouse has a back and a forward button, these are not usable and input will be ignored.
evrouter
can be used to work around this limitation by sending keyboard key presses when clicking the mouse back/forward buttons. Optionally, xte found in
xautomation
and
xbindkeys
can be used on the server to map the keyboard key presses back to mouse button clicks if needed.
Substituting mouse back/forward buttons with keyboard keys XF86Back/XF86Forward
This method is simple and suitable if you only need a way to navigate backward/forward while using web browsers or file browsers for example.
Install
evrouter
AUR
and
xautomation
on the client. Configure evrouter, see
Mouse buttons#evrouter
and evrouter man pages for instructions and tips on how to find the correct device name, window name, button names etc. Example config:
~/.evrouterrc
Window "OtherComputer:0 - TigerVNC": # Window title used as filter

# Using Shell to avoid repeating key presses (see evrouter manual)
"USB mouse" "/dev/input/by-id/usb-Mouse-name-event-mouse" none key/275 "Shell/xte 'key XF86Back'"
"USB mouse" "/dev/input/by-id/usb-Mouse-name-event-mouse" none key/276 "Shell/xte 'key XF86Forward'"

# Use XKey below instead if repeating keys is desired (see evrouter manual)
#"Logitech Gaming Mouse G400" "/dev/input/by-id/usb-Logitech_Gaming_Mouse_G400-event-mouse" none key/275 "XKey/XF86Back"
#"Logitech Gaming Mouse G400" "/dev/input/by-id/usb-Logitech_Gaming_Mouse_G400-event-mouse" none key/276 "XKey/XF86Forward"
Start evrouter on the client. With above configuration keyboard key
XF86Back
is sent to the VNC server when clicking the back button on the mouse, and
XF86Forward
is sent when clicking the forward button.
Mapping the keyboard key presses back to mouse button clicks on the server
If needed, it is possible to map the keyboard keys back to mouse button clicks on the server. In this case, it might be a good idea to use keyboard keys which are never on the client or server. In the example below, keyboard keys
XF86Launch8
/
XF86Launch9
are used as mouse buttons 8/9.
Evrouter configuration on the client:
~/.evrouterrc
Window "OtherComputer:0 - TigerVNC": # Window title

# Using Shell to avoid repeating key presses (see evrouter manual)
"USB mouse" "/dev/input/by-id/usb-Mouse-name-event-mouse" none key/275 "Shell/xte 'key XF86Launch8'"
"USB mouse" "/dev/input/by-id/usb-Mouse-name-event-mouse" none key/276 "Shell/xte 'key XF86Launch9'"
Install
xautomation
and
xbindkeys
on the server. Configure xbindkeys to map keyboard keys
XF86Launch8
/
XF86Launch9
to mouse buttons 8/9 with xte.
~/.xbindkeysrc
"xte 'mouseclick 8'"
     XF86Launch8

"xte 'mouseclick 9'"
     XF86Launch9
Start xbindkeys (
xbindkeys -f ~/.xbindkeysrc
). The server will now map
XF86Launch8
/
XF86Launch9
to mouse buttons 8/9.
Troubleshooting
Black rectangle instead of window
Most probably, this is due to the application strictly requiring the composite Xorg extension.  For example webkit based app: midori, psi-plus, etc.
Restart vncserver in this case using something like following:
$ vncserver -geometry ... -depth 24 :1 +extension Composite
It looks like Composite extension in VNC will work only with 24bit depth.
Empty black window with mouse cursor or xinit: connection to X server lost
Verify that the user is not logged into a physical X session, unless this option was configured with
x0vncserver
. Multiple X sessions for a single user are not supported, see
684#issuecomment-494385395
and
#1634
.
Conversely, trying to log into a local X session while a VNC server service is running for that user will likely not work, and may get stuck on a splash screen when using a desktop environment.
No mouse cursor
If no mouse cursor is visible when using
x0vncserver
, start
vncviewer
as follows:
$ vncviewer DotWhenNoCursor=1
server
Alternatively, put
DotWhenNoCursor=1
in the TigerVNC configuration file, which is at
$XDG_CONFIG_HOME/tigervnc/default.tigervnc
by default.
Copying clipboard content from the remote machine
If copying from the remote machine to the local machine does not work, run
autocutsel
on the server, as mentioned in
[1]
:
$ autocutsel -fork
Now, press
Ctrl+Alt+m
to display the VNC menu popup, and select
Clipboard: local > remote
option.
No window decoration / borders / titlebars / cannot move windows around
Start a window manager to fix an empty
xterm
frame. For example, on
Xfce
, run
xfwm4 &
.
Desktop environment is displaying only boxes for font
Some
desktop environments
might be missing necessary font to display ASCII characters.
Install
ttf-dejavu
.
VNC server terminates immediately while using xfce4 session
Create a new
.desktop
file under
/usr/share/xsessions
. For example:
/usr/share/xsessions/xfce4vnc.desktop
[Desktop Entry]
Version=1.0
Name=Xfce4vnc Session
Exec=dbus-launch startxfce4
Icon=
Type=Application
DesktopNames=XFCE4VNC
Make sure the
Exec
key is using
dbus-launch
to start xfce4 within new session bus instance context. Remember to change
session
value in
$XDG_CONFIG_HOME/tigervnc/config
to
xfce4vnc
.
See also
https://github.com/TigerVNC/tigervnc