X11vnc - ArchWiki

# X11vnc

Related articles

- TigerVNC

x11vnc 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. In this way it plays the role for Unix/X11 that WinVNC plays for Windows.

Note: x11vnc is not the only way to accomplish a remote control of the real X display; x0vncserver is part of tigervnc and allows for the same operation.

## Setting up x11vnc

### Installation

x11vnc is available in the official repositories.

### Starting

First, start X either by startx or through a manager such as GDM or SLiM. You may need to set up X to run headless too. Then, open a terminal and type

    $ x11vnc -display :0

Another option is to place the x11vnc line in a script which is called at login.

    #!/bin/bash
    x11vnc -nap -wait 50 -noxdamage -passwd PASSWORD -display :0 -forever -o /var/log/x11vnc.log -bg

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

    $ x11vnc -display :0 -auth ~/.Xauthority

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

    # x11vnc -display :0 -auth /home/user/.Xauthority

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

##### 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.

    # x11vnc -display :0 -auth /var/lib/gdm/:0.Xauth

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

    # x11vnc -display :0 -auth /run/user/120/gdm/Xauthority

or see Troubleshooting section below

##### SLIM

    # x11vnc -display :0 -auth /var/run/slim.auth

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[1].

##### LXDM

    # x11vnc -display :0 -auth /var/run/lxdm/lxdm-\:0.auth

#### Setting a password

    $ mkdir ~/.x11vnc
    $ x11vnc -storepasswd password ~/.x11vnc/passwd

To connect using the stored password use the `-rfbauth` argument and point to the passwd file you created, like so:

    $ x11vnc -display :0 -rfbauth ~/.x11vnc/passwd

Your viewer should 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 the -many or -forever argument, like this:

    $ x11vnc -many -display :0

or

    $ x11vnc -forever -display :0

### 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 ):

    $ ssh -t -L 5900:localhost:5900 remote_host 'sudo x11vnc -display :0 -auth /home/USER/.Xauthority'

where USER is the username of the user who is running the X server.

(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:

    $ vncviewer -encodings "copyrect tight zrle hextile" localhost:0

## Troubleshooting

1. You can check your ip address and make sure port 5900 is forwarded by visiting this 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:

    $ ln -sv $(dirname $(xauth info | awk '/Authority file/{print $3}')) ~/.Xauthority

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

    $ ln -sf $(dirname $(xauth info | awk '/Authority file/{print $3}')) ~/.Xauthority

3. GNOME 3 and x11vnc

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

    *** XOpenDisplay failed (:0)

    *** x11vnc was unable to open the X DISPLAY: ":0", it cannot continue.

Try running x11vnc like

    $ x11vnc -noxdamage -many -display :0 -auth /var/run/gdm/$(sudo ls /var/run/gdm | grep $(whoami))/database -forever -bg

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

4. Screensaver problem

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

Categories:

- Security
- Remote desktop

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