Check Certificate using OpenSSL & How to Renew SSL Certificate Seamlessly

Maintaining a secure website requires vigilance, especially when it comes to SSL/TLS certificates. These certificates have finite lifespans, and letting one expire can lead to security warnings, loss of user trust, and service disruptions. Two critical tasks in the certificate lifecycle are verifying certificate details and managing renewals. For administrators comfortable with the command line, needing to Check Certificate using OpenSSL provides a powerful and flexible way to inspect certificate details. This often leads directly to the next crucial action: knowing how and when to Renew SSL Certificate.

This guide will demonstrate how to use the versatile OpenSSL toolkit to check certificate details both locally and remotely. We’ll then outline the standard process for renewing your SSL certificate, ensuring you can keep your website secure and trusted with certificates from providers like sslrepo.com.

Key Takeaways

• OpenSSL for Checks: OpenSSL is a powerful command-line tool to inspect SSL certificate details (issuer, subject, expiration, SANs, etc.) on remote servers or local files (.crt, .pem, .pfx).
• Expiration is Key: Regularly checking expiration dates (using OpenSSL or other tools) is vital to know when renewal is needed.
• Renewal Process: To Renew SSL Certificate, you typically need to:
  1. Generate a new Certificate Signing Request (CSR).
  2. Purchase the renewal from your CA/Reseller using the new CSR.
  3. Complete domain/organization validation.
  4. Install the newly issued certificate.
  5. Verify the installation.
• New CSR Recommended: Generating a new CSR (and thus a new private key) for each renewal is a security best practice.
• Proactive Renewal: Start the renewal process well before the expiration date (30-90 days recommended).

Part 1: How to Check Certificate using OpenSSL

OpenSSL is a robust cryptography toolkit available on Linux, macOS, and Windows (via installation or tools like Git Bash). It allows detailed inspection of certificates.

1. Checking a Remote Server’s SSL Certificate (Live Website)

This command connects to a server, retrieves its certificate, and displays details.

Explanation:

• openssl s_client: Initiates an SSL/TLS client connection.
• -connect yourdomain.com:443: Specifies the server hostname and port (443 is standard for HTTPS). Replace yourdomain.com with the actual domain.
• -servername yourdomain.com: Important for SNI (Server Name Indication). Tells the server which hostname’s certificate you’re requesting, crucial if multiple sites are hosted on the same IP.
• |: Pipes the output of s_client (which includes the certificate) to the next command.
• openssl x509: Utility for handling X.509 certificates.
• -noout: Prevents outputting the encoded certificate itself.
• -text: Displays the certificate information in human-readable text.

To check specific fields:

• Expiration Dates:BASHopenssl s_client -connect yourdomain.com:443 -servername yourdomain.com | openssl x509 -noout -dates (Look for notBefore and notAfter dates).
• Subject (Includes Common Name):BASHopenssl s_client -connect yourdomain.com:443 -servername yourdomain.com | openssl x509 -noout -subject
• Issuer:BASHopenssl s_client -connect yourdomain.com:443 -servername yourdomain.com | openssl x509 -noout -issuer

2. Checking a Local Certificate File (.crt, .cer, .pem)

If you have the certificate file saved locally:

BASHopenssl x509 -in /path/to/your_certificate.crt -noout -text

Explanation:

• -in /path/to/your_certificate.crt: Specifies the path to your certificate file.
• Other flags (-noout, -text, -dates, -subject, -issuer) work the same way as above.

3. Checking a PFX File (.pfx, .p12)

PFX files bundle the certificate(s) and private key.

BASHopenssl pkcs12 -info -in /path/to/your_certificate.pfx

Explanation:

• openssl pkcs12: Utility for handling PKCS#12 files.
• -info: Displays information about the PFX contents.
• -in /path/to/your_certificate.pfx: Specifies the path to your PFX file.
• You will likely be prompted for the import password (the one used when creating the PFX). You might also be prompted for a PEM passphrase if you choose to output keys, but often just viewing info doesn’t require it beyond the initial import password.

Key Information to Look For in Output:

• Subject: Includes Common Name (CN=), Organization (O=), etc. Verify the CN matches your domain.
• Issuer: Who issued the certificate (e.g., Sectigo, DigiCert).
• Validity: Not Before (Start Date) and Not After (Expiration Date).
• Subject Alternative Name (SAN): Lists any additional hostnames covered by the certificate.
• Public Key Algorithm & Size: (e.g., RSA 2048 bit).

Using OpenSSL to Check Certificate using OpenSSL gives you precise control and detailed information, perfect for scripting or deep dives.

Part 2: How to Renew SSL Certificate

Checking the certificate, especially its expiration date (notAfter), tells you when you need to renew. The renewal process ensures continuous HTTPS protection. While specific steps might vary slightly by CA or platform, the general workflow is consistent.

It’s crucial to understand that renewing an SSL certificate is technically very similar to obtaining a new one.

General Steps to Renew SSL Certificate:

1. Check Expiration Date: Use OpenSSL (as shown above), browser tools, online checkers, or your server’s management interface (like IIS Manager) to confirm the expiration date. Start the renewal process well in advance (30-90 days is recommended).
2. Generate a NEW Certificate Signing Request (CSR):
   • Best Practice: Always generate a new CSR for each renewal. This creates a new, unique private key on your server, enhancing security. Reusing old CSRs/keys is discouraged.
   • How: Use the same tools you used initially:
     • Windows/IIS: Use the “Create Certificate Request” feature in IIS Manager’s “Server Certificates” section.
     • Linux/OpenSSL: Use the openssl req command (e.g., openssl req -new -newkey rsa:2048 -nodes -keyout yourdomain_new.key -out yourdomain_new.csr).
     • Hosting Panels: Use the SSL/TLS section in cPanel, Plesk, etc.
   • Ensure the information (especially Common Name and any required SANs) is accurate for the renewal period.
3. Purchase the Renewal:
   • Go to your Certificate Authority or preferred SSL Reseller (like sslrepo.com).
   • Choose the appropriate certificate type for renewal (it should usually match your expiring certificate type – DV, OV, EV, Wildcard, etc.).
   • During the order process, you will be prompted to submit your newly generated CSR text.
4. Complete Validation: The CA needs to verify your identity/control again.
   • DV: Usually involves responding to an email, adding a DNS record, or uploading a file to your server.
   • OV/EV: Requires verification of your organization’s details (may be faster if details haven’t changed recently, but some verification is always needed). Respond promptly to any CA requests.
5. Receive and Install the New Certificate: Once validation is complete, the CA will issue the renewed certificate files (.crt, .cer, intermediate bundle).
   • Installation: Follow the installation procedure for your specific server platform (e.g., “Complete Certificate Request” in IIS, updating Apache/Nginx config files, using your hosting panel). This pairs the new certificate with the new private key generated in Step 2.
   • Don’t Forget Intermediates: Ensure any required intermediate certificates are also installed correctly.
6. Verify the Installation: After installation, thoroughly test your website:
   • Use a browser (clear cache) and check the padlock icon for the new expiration date.
   • Use openssl s_client again to Check Certificate using OpenSSL on the live site.
   • Use an online SSL checker tool to confirm the installation and chain are correct.
7. (Optional) Remove Old Certificate: Once you’ve confirmed the new certificate is working correctly, you can remove the old, expiring certificate from your server’s certificate store or configuration to avoid confusion.

Conclusion

OpenSSL provides a robust command-line method to Check Certificate using OpenSSL, giving administrators detailed insights into certificate properties, especially expiration dates. This information is crucial for initiating the Renew SSL Certificate process in a timely manner. Remember that renewal typically involves generating a fresh CSR, purchasing the renewal, completing validation, and carefully installing the new certificate. By proactively managing this cycle, you ensure your website remains secure, trusted, and continuously available to your users.

Stay ahead of expirations! Check your certificate dates today and explore easy renewal options at sslrepo.com.

Frequently Asked Questions (FAQ)

Q1: Can OpenSSL check the certificate on any website?
A: Yes, using the openssl s_client command, you can connect to any publicly accessible HTTPS website (port 443) and inspect the SSL certificate it presents.

Q2: What’s the most important date to check with OpenSSL?
A: The notAfter date, which indicates when the certificate expires. You need to renew before this date.

Q3: Do I have to generate a new CSR to renew my SSL certificate?
A: It is strongly recommended as a security best practice. Generating a new CSR creates a new private key. Most reputable CAs and resellers expect a new CSR for renewals.

Q4: How long does the SSL renewal process take?
A: It depends on the validation type. DV renewals can be very fast (minutes to hours) if validation is automated. OV/EV renewals take longer (typically 1-5 business days) due to manual organization checks. Start early!

Q5: Can I use OpenSSL to install the renewed certificate?
A: OpenSSL itself doesn’t directly “install” certificates into web server configurations like IIS or Apache. You use OpenSSL to check certificates or potentially convert formats (like CRT to PFX). Installation involves configuring your specific web server software (IIS, Apache, Nginx, etc.) to use the new certificate files.

Q6: My OpenSSL check shows the old certificate even after I installed the new one. Why?
A: Common reasons include:
* You haven’t restarted/reloaded your web server service (Apache, Nginx).
* You haven’t updated the website’s HTTPS binding in IIS to point to the new certificate.
* There might be a caching issue (server-side or CDN).
* You installed the certificate on the wrong server (in a load-balanced setup).