How to Set Up VNC Client noVNC on AlmaLinux

noVNC is a browser-based VNC (Virtual Network Computing) client that provides remote desktop access without requiring additional software on the client machine. By utilizing modern web technologies like HTML5 and WebSockets, noVNC allows users to connect to a VNC server directly from a web browser, making it a lightweight, platform-independent, and convenient solution for remote desktop management.

In this guide, we’ll walk you through the step-by-step process of setting up noVNC on AlmaLinux, a robust and secure enterprise-grade Linux distribution.

Why Choose noVNC?

noVNC offers several advantages over traditional VNC clients:

1. Browser-Based: Eliminates the need to install standalone VNC client software.
2. Cross-Platform Compatibility: Works on any modern web browser, regardless of the operating system.
3. Lightweight: Requires minimal resources, making it ideal for resource-constrained environments.
4. Convenient for Remote Access: Provides instant access to remote desktops via a URL.

Prerequisites

Before we begin, ensure you have the following:

1. AlmaLinux Installed: A fresh or existing installation of AlmaLinux with administrative access.
2. VNC Server Configured: A working VNC server, such as TigerVNC, installed and configured on your server.
3. Root or Sudo Access: Required for software installation and configuration.
4. Stable Internet Connection: For downloading packages and accessing the noVNC client.

Step 1: Update Your AlmaLinux System

As always, start by updating your system to ensure you have the latest packages and security patches:

sudo dnf update -y

Step 2: Install Required Dependencies

noVNC requires several dependencies, including Python and web server tools, to function correctly.

Install Python and pip

Install Python 3 and pip:

sudo dnf install -y python3 python3-pip

Verify the installation:

python3 --version
pip3 --version

Install Websockify

Websockify acts as a bridge between noVNC and the VNC server, enabling the use of WebSockets. Install it using pip:

sudo pip3 install websockify

Step 3: Download and Set Up noVNC

Clone the noVNC Repository

Download the latest noVNC source code from its GitHub repository:

git clone https://github.com/novnc/noVNC.git

Move into the noVNC directory:

cd noVNC

Verify the Files

Ensure the utils directory exists, as it contains important scripts such as novnc_proxy:

ls utils/

Step 4: Configure and Start the VNC Server

Ensure that a VNC server (e.g., TigerVNC) is installed and running. If you don’t have one installed, you can install and configure TigerVNC as follows:

sudo dnf install -y tigervnc-server

Start a VNC Session

Start a VNC session for a user (e.g., vncuser):

vncserver :1

• :1 indicates display 1, which corresponds to port 5901.
• Set a VNC password when prompted.

To stop the VNC server:

vncserver -kill :1

For detailed configuration, refer to the How to Configure VNC Server on AlmaLinux guide.

Step 5: Run noVNC

Start the Websockify Proxy

To connect noVNC to the VNC server, start the Websockify proxy. Replace 5901 with the port your VNC server is running on:

./utils/novnc_proxy --vnc localhost:5901

The output will display the URL to access noVNC, typically:

http://0.0.0.0:6080

Here:

• 6080 is the default port for noVNC.
• The URL allows you to access the VNC server from any modern browser.

Test the Connection

Open a web browser and navigate to:

http://<server-ip>:6080

Replace <server-ip> with the IP address of your AlmaLinux server. Enter the VNC password when prompted to access the remote desktop.

Step 6: Set Up noVNC as a Service

To ensure noVNC runs automatically on boot, set it up as a systemd service.

Create a Service File

Create a systemd service file for noVNC:

sudo nano /etc/systemd/system/novnc.service

Add the following content to the file:

[Unit]
Description=noVNC Server
After=network.target

[Service]
Type=simple
User=root
ExecStart=/usr/bin/python3 /path/to/noVNC/utils/novnc_proxy --vnc localhost:5901
Restart=always

[Install]
WantedBy=multi-user.target

Replace /path/to/noVNC with the path to your noVNC directory.

Reload Systemd and Start the Service

Reload the systemd daemon to recognize the new service:

sudo systemctl daemon-reload

Start and enable the noVNC service:

sudo systemctl start novnc
sudo systemctl enable novnc

Check the status of the service:

sudo systemctl status novnc

Step 7: Configure the Firewall

To allow access to the noVNC web client, open port 6080 in the firewall:

sudo firewall-cmd --permanent --add-port=6080/tcp
sudo firewall-cmd --reload

Step 8: Secure noVNC with SSL

For secure access, configure noVNC to use SSL encryption.

Generate an SSL Certificate

Use OpenSSL to generate a self-signed SSL certificate:

sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/ssl/private/novnc.key -out /etc/ssl/certs/novnc.crt

• Enter the required details when prompted.
• This generates novnc.key and novnc.crt in the specified directories.

Modify the noVNC Service

Update the noVNC service file to include SSL:

ExecStart=/usr/bin/python3 /path/to/noVNC/utils/novnc_proxy --vnc localhost:5901 --cert /etc/ssl/certs/novnc.crt --key /etc/ssl/private/novnc.key

Reload and restart the service:

sudo systemctl daemon-reload
sudo systemctl restart novnc

Test Secure Access

Access the noVNC client using https:

https://<server-ip>:6080

Step 9: Access noVNC from a Browser

1. Open the URL: Navigate to the noVNC URL displayed during setup.
2. Enter the VNC Password: Provide the password set during VNC server configuration.
3. Start the Session: Once authenticated, you’ll see the remote desktop interface.

Step 10: Troubleshooting noVNC

Common Issues and Fixes

1. Black Screen After Login:

   • Ensure the VNC server is running: vncserver :1.
   • Check if the VNC server is using the correct desktop environment.

2. Cannot Access noVNC Web Interface:

   • Verify the noVNC service is running: sudo systemctl status novnc.
   • Ensure port 6080 is open in the firewall.

3. Connection Refused:

   • Confirm that Websockify is correctly linked to the VNC server (localhost:5901).

4. SSL Errors:

   • Verify the paths to the SSL certificate and key in the service file.
   • Test SSL connectivity using a browser.

Conclusion

By setting up noVNC on AlmaLinux, you’ve enabled a powerful, browser-based solution for remote desktop access. This configuration allows you to manage your server graphically from any device without the need for additional software. With steps for securing the connection via SSL, setting up a systemd service, and optimizing performance, this guide ensures a robust and reliable noVNC deployment.

noVNC’s lightweight and platform-independent design, combined with AlmaLinux’s stability, makes this setup ideal for both personal and enterprise environments. Enjoy the convenience of managing your server from anywhere!