How to Use Nginx as a Reverse Proxy

Step 1: Install Nginx

If you haven't already installed Nginx, you can do so on Ubuntu or Debian-based systems using the following commands:

sudo apt update
sudo apt install nginx

For CentOS or RedHat-based systems, use:

sudo yum install nginx

Step 2: Start and Enable Nginx

After installation, start the Nginx service and enable it to start on boot:

sudo systemctl start nginx
sudo systemctl enable nginx

Step 3: Configure Nginx as a Reverse Proxy

To configure Nginx to act as a reverse proxy, you need to modify the Nginx configuration file.

Open the Nginx configuration file:

sudo nano /etc/nginx/sites-available/default

Modify the server block to include a reverse proxy configuration. For example:

server {
    listen 80;

    server_name yourdomain.com;  # Replace with your domain or public IP

    location / {
        proxy_pass http://localhost:3000;  # Replace with the backend server address
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}

In this configuration:

proxy_pass points to the backend server (in this case, it's http://localhost:3000).
proxy_set_header Ensures that the correct headers are passed to the backend server.
proxy_http_version Ensures the use of HTTP/1.1 for WebSocket support (if needed).

Save the file and exit the editor.

Step 4: Test Nginx Configuration

Before restarting Nginx, it's a good practice to test the configuration for syntax errors:

sudo nginx -t

If the configuration is correct, you should see a message that says "syntax is okay" and "test is successful."

Step 5: Restart Nginx

Now, restart Nginx to apply the changes:

sudo systemctl restart nginx

Step 6: Adjust Firewall Rules (if applicable)

If you have a firewall enabled, ensure that HTTP traffic is allowed through the firewall.

For UFW (Ubuntu firewall), run:

sudo ufw allow 'Nginx Full'

For Firewalld (CentOS/RHEL), run:

sudo firewall-cmd --zone=public --add-service=http --permanent
sudo firewall-cmd --reload

Step 7: Verify the Reverse Proxy

Now, visit your server's public IP or domain in a browser. If everything is configured correctly, Nginx should forward the requests to the backend server (e.g., a Node.js or any other application running on port 3000) and return the content.

For example, if your Nginx server is acting as a reverse proxy to a web server running on localhost:3000, accessing http://yourdomain.com will load content from the server running on localhost:3000.

Step 8: Configure SSL (Optional)

If you want to set up SSL (HTTPS) with Nginx, you can use Let's Encrypt for a free SSL certificate. Here are the steps:

Install Certbot:

sudo apt install certbot python3-certbot-nginx

Obtain the SSL certificate:

sudo certbot --nginx -d yourdomain.com

Follow the instructions to complete the SSL setup. Certbot will automatically configure SSL for you in Nginx.

Step 9: Test the Reverse Proxy

Finally, test everything:

Check your Nginx logs for any issues: sudo tail -f /var/log/nginx/error.log.
Ensure that your backend service is running and accessible.

Souy Soeng