When deploying an Internet Information Services (IIS) server on Windows Server 2016, you may encounter an issue where certificates generated by Microsoft Certificate Authority (CA) within Active Directory (AD) are not recognized. This can create problems for secure communications over HTTPS, ultimately affecting user experience and trust in your website. Below, we’ll break down the problem and provide solutions to ensure that your certificates are recognized and functioning as intended.
The Original Problem
Here is a simplified version of the initial problem statement for clarity:
"Certificates generated by Microsoft Certification Authority in Active Directory on Windows Server 2016 are not recognized by IIS."
Understanding the Issue
The issue at hand can be attributed to several factors, which might include incorrect configurations, missing intermediate certificates, or even trust issues with the root CA. Here’s a breakdown of potential causes and solutions:
1. Certificate Trust Chain
One of the most common reasons for IIS not recognizing a certificate is that the certificate trust chain is broken. Ensure that the root and intermediate certificates are installed on the IIS server.
How to Check:
- Open the Certificates MMC snap-in: Run
mmc.exeand add the Certificates snap-in for the Local Computer. - Navigate to Trusted Root Certification Authorities and Intermediate Certification Authorities to verify the presence of the required certificates.
2. Correct Application of the Certificate
It’s essential that the certificate is properly bound to the site in IIS. This involves ensuring that the site configuration is correct and the right certificate is selected.
Steps to Bind the Certificate:
- Open IIS Manager.
- Select your site in the Connections pane.
- In the Actions pane, click on Bindings.
- Make sure that the HTTPS binding uses the correct certificate by checking the certificate selection.
3. Client Trust Issue
Even if the server recognizes the certificate, clients (browsers, applications) might not recognize it if they do not trust the issuing CA.
Resolution:
- Ensure that clients have the necessary CA certificates installed in their trusted root store.
4. Certificate Revocation List (CRL)
Certificates may also fail if the corresponding CRL cannot be reached. Ensure that the CRL endpoint is accessible from your server and that the CRL has not expired.
Verifying CRL Access:
- You can check CRL endpoints by reviewing the properties of the certificate in the Certificates MMC.
Practical Example
Let’s say you have set up a web application on IIS, and you have an SSL certificate issued by your internal CA. You might visit your website and encounter a security warning stating that the certificate is not recognized.
After investigating:
- You check the installed certificates and find your CA’s root certificate is not present in the Trusted Root Certification Authorities store.
- Once you install the root certificate and restart IIS, your SSL certificate is now trusted and does not throw warnings in the browser.
Conclusion
In summary, if your IIS server on Windows Server 2016 is not recognizing certificates generated by Microsoft Certification Authority in AD, it’s crucial to verify the trust chain, binding settings, client trust, and CRL accessibility. By following the outlined steps, you should be able to troubleshoot and resolve the issues effectively.
Useful Resources
- Microsoft Docs - Install a Certificate
- Understanding SSL/TLS Certificate Chains
- IIS SSL Certificate Binding
By ensuring that you address these elements, you will not only enhance the security of your IIS-hosted applications but also provide a seamless experience for your users.
