TigerVNC provides the levels of performance necessary to run 3D and video applications, and it attempts to maintain a common look and feel and re-use components, where possible, across the various platforms that it supports. TigerVNC also provides extensions for advanced authentication methods and TLS encryption. TigerVNC works on the client-server principle: a server shares its output (vncserver) and a client (vncviewer) connects to the server. Note Unlike in previous Red Hat Enterprise Linux distributions, TigerVNC in Red Hat Enterprise Linux 7 uses the systemd system management daemon for its configuration. To set x11vnc to request access each time when set without a password, include the -nopw -accept popup:0 options. To set x11vnc to only listen for the next connection, include the -once option. To set x11vnc to continually listen for connections, include the -forever option. To put x11vnc in view-only mode, include the -viewonly option.

x11vnc is a VNC server, it allows one to view remotely and interact with real X displays (i.e. a display corresponding to a physical monitor, keyboard, and mouse) with any VNC viewer. While it is not developed any longer by its original author Karl Runge, LibVNC and the GitHub community have taken over the development.

x11vnc does not create an extra display (or X desktop) for remote control. Instead, it shows in real time the existing X11 display, unlike Xvnc, part of TigerVNC, which is an alternatives VNC server available in the official repositories.

Also note that x11vnc is not shipped with a client viewer. Any VNC viewer should do the job and be compatible with the x11vnc server while not necessarily using all its functionalities. TigerVNC's vncviewer is a recommended client.

Setting up x11vnc

Installation

Install x11vnc from the official repositories.

Starting

First, start X either by startx or through a display manager. You may need to set up X to run headless too.

Then, run the following command, all available options are explained in x11vnc(1).

Another option is to place the x11vnc command line in a script which is called at login, for example:

Note: The password 'PASSWORD' above is not secured; anyone who can run ps on the machine will see it. Also note that /var/log/x11vnc.log needs to be created manually and its ownership needs to match that of the user who will run it.

Setting X authority

You may set an X authority file for the VNC server. This is accomplished by using the -auth argument followed by the appropriate file, which will depend on how your X server was started. Generally, assigning an X authority file requires running x11vnc as root.

Start X

If that fails, you may have to run instead (as root):

Where user is the username of the user who is running the X server.

Running from xinetd

X11vnc can be run using a xinetd service, which only starts X11vnc once a user connects.

Create an xinetd service entry for x11vnc, for example:

After reloading xinetd.service, X11vnc will start once a client connects to port 5900.

Systemd

To run x11vnc when system boots, create the override with systemctl edit x11vnc.service. The content should be like the following

Replace the second ExecStart with the command you run interactively. Run systemctl enable x11vnc.service if you need.

GDM

Note: Newer GDM packages ship with Xwayland as the default display server backend. The following instructions, however, only apply when using Xorg (else .Xauthority is not created, and x11vnc fails to start). You are therefore advised to uncomment #WaylandEnable=false setting in /etc/gdm/custom.conf in order to proceed.

Newer versions of GDM uses /run/user. Example for user 120 (gdm), used for login screen.

or see Troubleshooting section below

Lightdm

Running from the bash:

LXDM

SDDM

SDDM uses an unpredictable UUID for the auth file [1] therefore one needs to:

Embedding this into a systemd .service file will require a trick to evaluate the find command as shown here [2].

SLIM

Warning: This will set up VNC with NO PASSWORD. This means that ANYBODY who has access to the network the computer is on CAN SEE YOUR XSERVER. It is a fairly simple matter to tunnel your VNC connection through SSH to avoid this. Or, simply set a password, as described below.

Note: The password will only encrypt the login process itself. The transmission is still unencrypted[3].

Setting a password

Running:

uses the password found in ~/.vnc/passwd, where the password is obscured with a fixed key in a VNC compatible format, or alternatively in ~/.vnc/passwdfile, where the first line of the file contains the password.If none of these files can be located, it prompts the user for a password which is saved in ~/.vnc/passwd and is used right away.

The VNC viewer should then prompt for a password when connecting.

Running constantly

By default, x11vnc will accept the first VNC session and shutdown when the session disconnects.In order to avoid that, start x11vnc with either the -many or the -forever argument, like this:

It is also possible to use the following command :

this will restart the server once the session is finished

Accessing

Get a VNC client on another computer, and type in the IP address of the computer running x11vnc. Hit connect, and you should be set.

If you are attempting to access a VNC server / computer (running x11vnc) from outside of its network then you will need to ensure that it has port 5900 forwarded.

SSH Tunnel

You need to have SSH installed and configured.

Use the -localhost flag with x11vnc for it to bind to the local interface. Once that is done, you can use SSH to tunnel the port; then, connect to VNC through SSH.

Simple example (from http://www.karlrunge.com/x11vnc/index.html#tunnelling ):

(You will likely have to provide passwords/passphrases to login from your current location into your remote_host Unix account; we assume you have a login account on remote_host and it is running the SSH server)

And then in another terminal window on your current machine run the command:

Troubleshooting

1. You can check your ip address and make sure port 5900 is forwarded by visiting this^{[dead link 2020-04-03 ⓘ]} website.

The factual accuracy of this article or section is disputed.

Reason:please use the first argument of the template to provide a brief explanation. (Discuss in Talk:X11vnc#)

2. Tested only on GNOME + GDM

If you cannot start the tunnel, and get error like XOpenDisplay(':0') failed,Check if you have a ~/.Xauthority directory.If that does not exist, You can create one easily (Actually a symlink to actual one) by running command given below as normal user NOT ROOT OR USING Sudo as below:

then try above tunneling example and it should work fine.Further if you want this to be automatically done each time Xorg is restarted, create the xprofile file & make is executable as below

3. GNOME 3 and x11vnc

If you are using GNOME 3 and x11vnc and you get the following errors

Try running x11vnc like

Please update if this works / not works for any other display manager or desktop environment.

Screensaver problem

If screensaver starts every 1-2 second, start x11vnc with -nodpms key.

X11vnc Vs Tigervnc