Troubleshooting Certbot SSL Installation on AWS EC2: A Journey to Success

Recently, I encountered an issue while trying to install an SSL certificate using Certbot on my AWS EC2 Ubuntu instance. The error message was quite perplexing:

Certbot failed to authenticate some domains (authenticator: nginx). The Certificate Authority reported these problems:
  Domain: mysite.com
  Type:   unauthorized
  Detail: 2a02:4780:3:1198:0:1534:b116:3: Invalid response from http://mysite.com/.well-known/acme-challenge/t3ikbSkN8pJDJZOHlBWkklBSrO2AGfwNtyb_gDBpFtU: 404

Hint: The Certificate Authority failed to verify the temporary nginx configuration changes made by Certbot. Ensure the listed domains point to this nginx server and that it is accessible from the internet.

Initial Troubleshooting Steps

I tried several common solutions to resolve the issue:

1. DNS Configuration:
   • Verified that the DNS records were correctly pointing to my EC2 instance.
   • Added CNAME records to ensure proper domain resolution.
2. Nginx Configuration:
   • Checked the Nginx configuration to ensure it was correctly serving files from the .well-known/acme-challenge directory.
   • Created test files to verify accessibility.
3. File Permissions:
   • Ensured that the Nginx user had the necessary permissions to read the challenge files.
4. Security Group Configuration:
   • Ensured that the EC2 instance's security groups allowed inbound traffic on ports 80 (HTTP) and 443 (HTTPS). This is crucial for Certbot to perform domain validation:

   # Example security group rules
   Inbound Rules:
   Type        Protocol    Port Range    Source
   HTTP        TCP         80            0.0.0.0/0
   HTTPS       TCP         443           0.0.0.0/0
   SSH         TCP         22            Your IP
   

Despite these efforts, the error persisted. The Certificate Authority was still unable to verify the domain, resulting in a 404 error.

The Real Issue: HTTPS Port Configuration

After much troubleshooting, I realized the root cause was related to the Nginx configuration for the HTTPS port. My initial Nginx configuration looked like this:

listen 80;
listen [::]:80;

# SSL configuration
#
# listen 443 ssl;
# listen [::]:443 ssl;

The SSL configuration lines were commented out, meaning Nginx was not listening on port 443 for HTTPS traffic. This prevented Certbot from completing the SSL verification process.

The Solution

To resolve the issue, I enabled the HTTPS port in the Nginx configuration by uncommenting the relevant lines:

listen 80;
listen [::]:80;

# SSL configuration
#
listen 443 ssl;
listen [::]:443 ssl;

After making this change, I restarted Nginx to apply the new configuration:

sudo systemctl restart nginx

Successful SSL Installation

With the HTTPS port enabled, I ran Certbot again:

sudo certbot certonly --nginx

and followed the prompts.

This time, Certbot successfully authenticated the domain and installed the SSL certificate without any issues.

then I added the certifcate and private key paths in the nginx configration file.

server {
    listen 80;
    listen [::]:80;

    listen 443 ssl;
    listen [::]:443 ssl;

    ssl_certificate    /etc/letsencrypt/live/mysite.com/fullchain.pem;
    ssl_certificate_key    /etc/letsencrypt/live/mysite.com/privkey.pem;

    #-- rest of the configuration

and restart the nginx one more time..

sudo systemctl restart nginx

That's it. The website successfully installed SSL!

Conclusion

This experience highlighted the importance of ensuring that all necessary ports are correctly configured in the web server settings. If you encounter similar issues with Certbot, double-check your Nginx configuration to ensure that both HTTP and HTTPS ports are enabled and properly configured.

By sharing this journey, I hope to help others who might face similar challenges in their SSL installation process. Happy securing! 🚀🔒

If you have any questions or need further assistance, feel free to reach out!