SSL certificates are crucial for secure connections between servers and clients. Ensuring the correct SSL certificate chain is in place is essential for a seamless browsing experience. This knowledge base provides detailed information on how to validate and troubleshoot SSL certificate chains in WHM cPanel.

1. Accessing SSL/TLS Configuration:

   • Log in to WHM.

   • Navigate to the 'Service Configuration' section.

   • Click on 'Manage SSL/TLS'.

2. Viewing Installed SSL Certificates:

   • In 'Manage SSL Hosts', you can view all installed SSL certificates.

   • Verify that each domain has the correct certificate installed.

3. Checking SSL Chain Certificates:

   • Click on 'Certificate' next to the domain to view its certificate details.

   • Verify the 'Certificate Authority Bundle (optional)' field.

   • Ensure it contains the complete chain of certificates, from the domain certificate to the root certificate.

4. Obtaining and Installing Intermediate Certificates:

   • If the chain is incomplete, you may need to obtain intermediate certificates from the certificate authority (CA).

   • Upload and install them in 'Manage SSL Hosts'.

5. Verifying Certificate Chain Order:

   • Ensure that the certificates are in the correct order in the CA bundle.

   • The root certificate should be at the top, followed by any intermediate certificates.

6. Running an SSL Test:

   • Utilize external tools like SSL Labs or Qualys SSL Server Test to perform a comprehensive SSL test on your domain.

   • These tests will highlight any issues with the SSL certificate chain.

7. Checking SSL Installation Guides:

   • Review the installation guides provided by your CA for specific instructions on installing certificates in WHM cPanel.

8. Renewing SSL Certificates:

   • Regularly check the expiration date of your SSL certificates.

   • Renew them before they expire to avoid disruptions in secure connections.

9. Utilizing AutoSSL:

   • WHM cPanel includes AutoSSL, which can automatically provision and install SSL certificates for your domains.

   • Ensure that AutoSSL is enabled and configured.

10. Implementing OCSP Stapling (Optional):

    • OCSP Stapling enhances SSL performance and security by allowing the server to include the OCSP response in the SSL handshake.

    • Enable this feature in 'Manage SSL/TLS'.

11. Checking for Mixed Content:

    • Ensure that all resources on your website are loaded securely (https://) to prevent mixed content warnings.

12. Monitoring SSL Logs:

    • Review SSL logs in WHM for any errors or warnings related to certificate validation.

13. Understanding Certificate Revocation Lists (CRLs):

    • CRLs are lists of revoked SSL certificates.

    • Ensure that your server can access the CRLs of your CA to validate certificates.

14. Consulting Certificate Authorities for Support:

    • If you encounter issues with your SSL certificate chain, contact your CA's support for assistance.

15. Enabling HSTS (Optional):

    • HTTP Strict Transport Security (HSTS) enforces secure connections by instructing browsers to always use HTTPS.

    • Enable this feature in 'Manage SSL/TLS'.

Conclusion:

Ensuring the correct SSL certificate chain is vital for secure connections on your server. By following the steps outlined in this knowledge base, you can validate and troubleshoot SSL certificate chains in WHM cPanel effectively. Regular monitoring and maintenance of SSL certificates will help maintain a secure and reliable browsing experience for your users.