How to Secure Nginx with Let’s Encrypt SSL on Ubuntu 24.04

ByAkensai

Learning How to Secure Nginx with Let’s Encrypt SSL on Ubuntu 24.04 is one of the most important skills for any server administrator. Without SSL, your website sends data in plain text. That means passwords, form submissions, and user data are exposed. Let’s Encrypt solves this by providing free, trusted SSL certificates. It’s automated, widely supported, and trusted by all major browsers. By the end of this tutorial, you’ll have a fully secured Nginx server with automatic certificate renewal. This guide works for personal sites, WordPress installations, and production web applications alike.

Prerequisites for How to Secure Nginx with Let’s Encrypt SSL on Ubuntu 24.04

Before you start, make sure you have everything in place. Missing a requirement will cause the process to fail.

You will need:

– A fresh Ubuntu 24.04 server (VPS or dedicated)
– A registered domain name pointing to your server’s IP address
– Nginx installed and running
– Root or sudo access to the server
– Basic familiarity with the Linux terminal

Estimated time: 15–20 minutes

Your DNS records must be fully propagated before you request a certificate. Let’s Encrypt verifies domain ownership by making an HTTP request to your server. If your domain doesn’t resolve to your server’s IP, the verification will fail.

You can check DNS propagation using a tool like MXToolbox DNS Lookup before proceeding.

Also confirm that ports 80 and 443 are open on your firewall. Run sudo ufw status to check. If Nginx is not yet installed, run:

sudo apt update
sudo apt install nginx -y
sudo systemctl enable nginx
sudo systemctl start nginx

Once Nginx is running and your domain resolves correctly, you’re ready to begin.

Step-by-Step Guide to How to Secure Nginx with Let’s Encrypt SSL on Ubuntu 24.04

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Follow these steps carefully. Each one builds on the last.

Step 1: Update your system packages

Always start with a system update. This ensures you’re installing the latest software versions.

sudo apt update && sudo apt upgrade -y

Step 2: Install Certbot and the Nginx plugin

Certbot is the official client for Let’s Encrypt. The Nginx plugin handles configuration changes automatically.

sudo apt install certbot python3-certbot-nginx -y

Step 3: Configure your Nginx server block

Before requesting a certificate, set up a proper server block for your domain. Open or create your config file:

sudo nano /etc/nginx/sites-available/yourdomain.com

Add the following configuration. Replace yourdomain.com with your actual domain:

server {
    listen 80;
    server_name yourdomain.com www.yourdomain.com;

    root /var/www/yourdomain.com/html;
    index index.html index.htm index.php;

    location / {
        try_files $uri $uri/ =404;
    }
}

Save the file and enable it:

sudo ln -s /etc/nginx/sites-available/yourdomain.com /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx

The nginx -t command tests your configuration for syntax errors. Never reload Nginx without running this test first.

Step 4: Allow HTTPS through the firewall

Open both HTTP and HTTPS ports using UFW:

sudo ufw allow 'Nginx Full'
sudo ufw delete allow 'Nginx HTTP'

The first command opens ports 80 and 443. The second removes the old HTTP-only rule to keep things clean.

Step 5: Request your SSL certificate

Now run Certbot. The --nginx flag tells it to modify your Nginx config automatically:

sudo certbot --nginx -d yourdomain.com -d www.yourdomain.com

Certbot will ask for your email address and prompt you to agree to the Terms of Service. It will then contact Let’s Encrypt, verify your domain, and install the certificate.

You’ll see output confirming the certificate was issued and saved to /etc/letsencrypt/live/yourdomain.com/.

Step 6: Verify automatic renewal

Let’s Encrypt certificates expire every 90 days. Certbot installs a systemd timer that renews certificates automatically. Test it with a dry run:

sudo certbot renew --dry-run

If the dry run succeeds, renewal is working correctly. You don’t need to do anything else. Check the timer status anytime with:

sudo systemctl status certbot.timer

Step 7: Verify your SSL certificate

Open your browser and navigate to https://yourdomain.com. You should see a padlock icon in the address bar. You can also verify your SSL setup using the SSL Labs Server Test tool. Aim for an A or A+ rating.

Troubleshooting Common Issues When Securing Nginx with SSL

Even with careful setup, things can go wrong. Here are the most common problems and how to fix them.

Error: “Could not bind to IPv4 or IPv6”

This usually means another process is using port 80. Check with:

sudo ss -tlnp | grep :80

Stop the conflicting process before running Certbot again.

Error: “Domain verification failed”

This means Let’s Encrypt couldn’t reach your server. Check these things:

– Your domain’s A record points to the correct IP
– Port 80 is open in your firewall
– Nginx is running: sudo systemctl status nginx

Error: “nginx: configuration file test failed”

You have a syntax error in your Nginx config. Run sudo nginx -t to see the exact line causing the issue. Fix it before reloading.

Certificate not renewing automatically

Check if the Certbot timer is active:

sudo systemctl list-timers | grep certbot

If it’s not listed, enable it manually:

sudo systemctl enable certbot.timer
sudo systemctl start certbot.timer

Mixed content warnings in browser

This happens when your site loads HTTP resources over HTTPS. If you’re running WordPress, install an SSL plugin or update your site URL in Settings > General to use https://.

Conclusion

You now know How to Secure Nginx with Let’s Encrypt SSL on Ubuntu 24.04 from start to finish. Your server now encrypts all traffic between itself and your visitors. Certbot handles certificate renewal automatically, so you don’t need to worry about expiration. This setup is production-ready and follows current best practices. From here, you can explore hardening your SSL configuration further by disabling older TLS versions or enabling HTTP/2 in your Nginx server block. You might also want to set up a web application firewall or configure security headers like Strict-Transport-Security. A secure server is the foundation of everything else you build on top of it.

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