Understanding SSL Certificate Renewal Verification

When managing automated SSL certificate renewals, it’s crucial to verify that the automation is working correctly. This post walks through the process of checking certificate renewal status using OpenSSL.

Checking Certificate Dates

One of the most important aspects of SSL certificate management is ensuring timely renewals. Here’s how to check certificate expiration dates:

openssl s_client -connect your-domain:443 -servername your-domain.com < /dev/null 2>/dev/null | openssl x509 -noout -dates

This command does several things:

  1. Establishes an SSL connection to your domain
  2. Retrieves the certificate
  3. Extracts and displays the validity dates

Breaking Down the Command

Let’s examine each component:

  • openssl s_client: Initiates an SSL/TLS connection
  • -connect host:port: Specifies the target server
  • -servername: Important for SNI (Server Name Indication)
  • < /dev/null: Automatically closes the connection after getting the certificate
  • 2>/dev/null: Suppresses error messages
  • | openssl x509: Pipes the certificate to the x509 processor
  • -noout -dates: Shows only the validity dates

Best Practices for Certificate Automation

  1. Regular Monitoring
  • Set up automated checks to verify renewal success
  • Monitor certificate expiration dates proactively
  1. Automation Verification
  • Test your automation in development environments first
  • Implement monitoring for the automation itself
  1. Fallback Plans
  • Have manual procedures documented
  • Maintain emergency contact information for certificate providers

Troubleshooting Tips

If certificates aren’t renewing properly:

  1. Check automation logs
  2. Verify DNS settings
  3. Confirm proper permissions for renewal processes
  4. Validate domain ownership verification
  5. Review rate limits with your certificate provider