How to Install and Configure VNC on CentOS 8

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Install and Configure VNC on CentOS 8

Virtual Network Computing (VNC) is a graphical desktop sharing system that allows you to use your keyboard and mouse to remotely control another computer.

This article covers the steps to install and configure a VNC server on CentOS 8. We’ll also show you how to securely connect to the VNC server through an SSH tunnel.

Prerequisites

To follow this guide, you need to be logged in as a user with sudo privileges on your remote CentOS machine.

Installing Desktop Environment

Generally, servers don’t have a desktop environment installed. If the machine you want to connect to doesn’t have GUI, the first step is to install it. Otherwise, skip this step.

Run the following command to install Gnome, the default desktop environment in CentOS 8 on your remote machine:

sudo dnf groupinstall "Server with GUI"

Depending on your system, downloading and installing the Gnome packages and dependencies may take some time.

Installing VNC Server

TigerVNC is an actively maintained high-performance open-source VNC server. It is available in the default CentOS repositories. To install it, type:

sudo dnf install tigervnc-server

Configuring VNC Server

Unlike in previous versions of CentOS, TigerVNC in CentOS 8 is configured using the systemd daemon.

In this example, we’ll show you how to configure TigerVNC for one or more VNC users.

  1. Use the vncpasswd command to set up the password. Run the command as the user that will access the VNC server, do not use sudo:

    vncpasswd

    You will be prompted to enter and confirm the password and whether to set it as a view-only password. If you choose to set up a view-only password, the user will not be able to interact with the VNC instance with the mouse and the keyboard.

    The first time the vncpasswd command is run, it will create and store the password file in the user’s ~/.vnc directory.

    Password:
    Verify:
    Would you like to enter a view-only password (y/n)? n
    A view-only password is not used
    

    If you’re adding a second user, switch to it and set the password with vncpasswd.

  2. The next step is to configure TigerVNC to use Gnome. VNC reads the user configuration settings from the ~/.vnc/config file. Open the file and add the following:

    vim ~/.vnc/config
    session=gnome
    geometry=1920x1200
    localhost
    alwaysshared
    

    The session option specifies the session you want to start, and the geometry option specifies the size of the VNC desktop.

    Save and close the file . If you’re adding multiple users, repeat the same step.

  3. TigerVNC ships with a file that allows you to map a user to a particular port. The mapping is configured in the /etc/tigervnc/vncserver.users file:

    sudo vim /etc/tigervnc/vncserver.users

    The file uses <display_port>=<username> syntax. In the example below, we are mapping display port :1 to user linuxize. Use the same format to add more users.

    # TigerVNC User assignment
    #
    # This file assigns users to specific VNC display numbers.
    # The syntax is <display>=<username>. E.g.:
    #
    # :2=andrew
    # :3=lisa
    :1=linuxize
    

    :1 is the display port number on which the VNC server will run. In our case, the server is running on TCP port 5901 (5900+1). If you map another user, for example, to display port :2, the server will also listen on port 5902 (5900+2).

    What is important to understand is that when working with VNC servers, :X is a display port that refers to 5900+X.

Starting the Tigervnc Server

Once you’re done with the configuration, the last step is to start the VNC server.

To start and enable the VNC service for the user mapped to the display port :1, enter:

sudo systemctl enable vncserver@:1 --now

The VNC server will listen on port 5901, as we discussed in the previous section.

You can verify that the service is successfully started with:

sudo systemctl status vncserver@:1
● vncserver@:1.service - Remote desktop service (VNC)
   Loaded: loaded (/usr/lib/systemd/system/vncserver@.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2020-12-17 21:49:41 UTC; 8s ago
  ...

To enable VNC for other users, simply replace 1 with the display port mapped to the user.

Connecting to VNC server

VNC is not an encrypted protocol and can be subject to packet sniffing. The recommended approach is to create an SSH tunnel to securely forward traffic from your local machine on port 5901 to the remote server on the same port.

Set Up SSH Tunneling on Linux and macOS

If you run Linux, macOS, or any other Unix-based operating system on your machine, you can easily create a tunnel using the following ssh command:

ssh -L 5901:127.0.0.1:5901 -N -f -l username remote_server_ip

You will be prompted to enter the user password.

Do not forget to replace username and server_ip_address with your username and the IP address of your server.

Set Up SSH Tunneling on Windows

Windows users can set up SSH Tunneling using PuTTY .

Open Putty and enter your server IP Address in the Host name or IP address field.

VNC Putty

Under the Connection menu, expand SSH and select Tunnels. Enter the VNC server port (5901) in the Source Port field, enter server_ip_address:5901 in the Destination field and click on the Add button as shown in the image below:

VNC SSH Tunnel Putty

Go back to the Session page to save the settings so that you do not need to enter them each time. To login to the remote server, select the saved session and click on the Open button.

Connecting using Vncviewer

To connect to the remote Server, open your VNC viewer, and enter localhost:5901.

You can use any VNC viewer such as TigerVNC, TightVNC, RealVNC, UltraVNC, Vinagre, and VNC Viewer for Google Chrome .

We’re using TigerVNC:

VNC Viewer

Enter the password when prompted, and you should see the default Gnome desktop. It should look something like this:

VNC Desktop

That’s it! You can now start working on your remote desktop from your local machine using your keyboard and mouse.

Conclusion

We’ve shown you how to set up a VNC server and connect to a remote CentOS 8 machine.

Feel free to leave a comment if you have any questions.