How to Configure VNC Server on AlmaLinux

A Virtual Network Computing (VNC) server allows users to remotely access and control a graphical desktop environment on a server using a VNC client. Configuring a VNC server on AlmaLinux can make managing a server easier, especially for users more comfortable with graphical interfaces. This guide provides a detailed walkthrough for setting up and configuring a VNC server on AlmaLinux.

Why Use a VNC Server on AlmaLinux?

Using a VNC server on AlmaLinux offers several benefits:

1. Remote Accessibility: Access your server’s desktop environment from anywhere.
2. Ease of Use: Simplifies server management for users who prefer GUI over CLI.
3. Multiple User Sessions: Supports simultaneous connections for different users.
4. Secure Access: Can be secured with SSH tunneling for encrypted remote connections.

Prerequisites

Before proceeding, ensure you have the following:

1. AlmaLinux Installed: A clean installation of AlmaLinux with root or sudo access.
2. GUI Installed: GNOME or another desktop environment installed. (If not, follow the guide to install GNOME.)
3. Stable Internet Connection: Required for package downloads and remote access.
4. VNC Client: A VNC client like TigerVNC Viewer installed on your local machine for testing.

Step 1: Update the System

Start by updating your AlmaLinux system to ensure all packages are up to date:

sudo dnf update -y

This ensures you have the latest versions of the software and dependencies.

Step 2: Install the VNC Server

AlmaLinux supports the TigerVNC server, which is reliable and widely used.

Install TigerVNC Server

Run the following command to install the TigerVNC server:

sudo dnf install -y tigervnc-server

Step 3: Create a VNC User

It’s recommended to create a dedicated user for the VNC session to avoid running it as the root user.

Add a New User

Create a new user (e.g., vncuser) and set a password:

sudo adduser vncuser
sudo passwd vncuser

Assign User Permissions

Ensure the user has access to the graphical desktop environment. For GNOME, no additional configuration is usually required.

Step 4: Configure the VNC Server

Each VNC user needs a configuration file to define their VNC session.

Create a VNC Configuration File

Create a VNC configuration file for the user. Replace vncuser with your username:

sudo nano /etc/systemd/system/vncserver@:1.service

Add the following content to the file:

[Unit]
Description=Remote desktop service (VNC)
After=syslog.target network.target

[Service]
Type=forking
User=vncuser
Group=vncuser
WorkingDirectory=/home/vncuser

ExecStart=/usr/bin/vncserver :1 -geometry 1280x1024 -depth 24
ExecStop=/usr/bin/vncserver -kill :1

[Install]
WantedBy=multi-user.target

• :1 specifies the display number for the VNC session (e.g., :1 means port 5901, :2 means port 5902).
• Adjust the geometry and depth parameters as needed for your screen resolution.

Save and exit the file.

Reload the Systemd Daemon

Reload the systemd configuration to recognize the new service:

sudo systemctl daemon-reload

Step 5: Set Up a VNC Password

Switch to the vncuser account:

sudo su - vncuser

Set a VNC password for the user by running:

vncpasswd

You’ll be prompted to enter and confirm a password. You can also set a “view-only” password if needed, but it’s optional.

Exit the vncuser account:

exit

Step 6: Start and Enable the VNC Service

Start the VNC server service:

sudo systemctl start vncserver@:1

Enable the service to start automatically on boot:

sudo systemctl enable vncserver@:1

Verify the status of the service:

sudo systemctl status vncserver@:1

Step 7: Configure the Firewall

To allow VNC connections, open the required ports in the firewall. By default, VNC uses port 5900 + display number. For display :1, the port is 5901.

Open VNC Ports

Run the following command to open port 5901:

sudo firewall-cmd --permanent --add-port=5901/tcp
sudo firewall-cmd --reload

If you are using multiple VNC sessions, open additional ports as needed (e.g., 5902 for :2).

Step 8: Secure the Connection with SSH Tunneling

VNC connections are not encrypted by default. For secure access, use SSH tunneling.

Create an SSH Tunnel

On your local machine, establish an SSH tunnel to the server. Replace user, server_ip, and 5901 with appropriate values:

ssh -L 5901:localhost:5901 user@server_ip

This command forwards the local port 5901 to the server’s port 5901 securely.

Connect via VNC Client

Open your VNC client and connect to localhost:5901. The SSH tunnel encrypts the connection, ensuring secure remote access.

Step 9: Access the VNC Server

With the VNC server configured and running, you can connect from your local machine using a VNC client:

1. Open Your VNC Client: Launch your preferred VNC client.
2. Enter the Server Address: Use <server_ip>:1 if connecting directly or localhost:1 if using SSH tunneling.
3. Authenticate: Enter the VNC password you set earlier.
4. Access the Desktop: You’ll be presented with the graphical desktop environment.

Step 10: Manage and Troubleshoot the VNC Server

Stopping the VNC Server

To stop a VNC session, use:

sudo systemctl stop vncserver@:1

Restarting the VNC Server

To restart the VNC server:

sudo systemctl restart vncserver@:1

Logs for Debugging

If you encounter issues, check the VNC server logs for details:

cat /home/vncuser/.vnc/*.log

Step 11: Optimizing the VNC Server

To improve the performance of your VNC server, consider the following:

1. Adjust Resolution: Use a lower resolution for faster performance on slower connections. Modify the -geometry setting in the service file.
2. Disable Unnecessary Effects: For GNOME, disable animations to reduce resource usage.
3. Use a Lightweight Desktop Environment: If GNOME is too resource-intensive, consider using a lightweight desktop environment like XFCE or MATE.

Conclusion

Configuring a VNC server on AlmaLinux provides a convenient way to manage your server using a graphical interface. By following this guide, you’ve installed and configured the TigerVNC server, set up user-specific VNC sessions, secured the connection with SSH tunneling, and optimized the setup for better performance.

AlmaLinux’s stability, combined with VNC’s remote desktop capabilities, creates a powerful and flexible system for remote management. Whether you’re administering a server or running graphical applications, the VNC server makes it easier to work efficiently and securely.