Resolving the SSLHandshakeException: No Subject Alternative Names Present

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Summary: Learn how to troubleshoot the SSLHandshakeException error, "No Subject Alternative Names Present," and ensure your SSL certificates function correctly.
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Resolving the SSLHandshakeException: No Subject Alternative Names Present

SSL/TLS is indispensable for securing online communication. One common issue that developers and system administrators encounter is the SSLHandshakeException with the message "No Subject Alternative Names Present." This article will help you understand this problem and guide you through the steps to resolve it effectively.

Understanding the Issue

What Is SSLHandshakeException?

SSLHandshakeException is an error that occurs during the SSL/TLS handshake process between a client and a server. The handshake is the phase where both entities establish a secure connection by exchanging cryptographic keys.

What Does "No Subject Alternative Names Present" Mean?

The message "No Subject Alternative Names Present" indicates that the SSL/TLS certificate presented by the server does not contain any Subject Alternative Names (SANs). SANs are used to specify additional host names for a single SSL certificate.

Causes of the Issue

Missing SAN Attribute

Modern browsers and Java applications require the SAN attribute in SSL certificates. If a certificate does not include SANs, it might lead to an SSL handshake failure.

Deprecated Usage of Common Name (CN)

Previously, the Common Name (CN) field within the Subject distinguished name was often used for SSL host validation. However, the current standard mandates using SANs instead of relying on the CN field.

Steps to Resolve the Issue

Check Your Certificate

First, inspect your SSL certificate to verify if it includes SANs. You can use tools like OpenSSL with the following command:

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Look for the X509v3 Subject Alternative Name section in the output.

Generate a New CSR with SANs

If your certificate lacks SANs, you'll need to generate a new Certificate Signing Request (CSR) that includes them. Here’s how to do it using OpenSSL:

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Generate the CSR:

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Obtain a New Certificate

Submit the newly generated CSR to your Certificate Authority (CA) to obtain a new certificate that includes SANs.

Update the Certificate on Your Server

Once you have the new certificate, update it on your server and restart the necessary services to apply the changes.

Verify the New Certificate

After deploying the new certificate, use the OpenSSL command or an online tool to ensure the SANs are present.

Conclusion

Dealing with an SSLHandshakeException due to missing Subject Alternative Names can be frustrating, but the solution is straightforward. Ensuring your SSL certificates include SANs in line with modern standards will mitigate this issue and help maintain secure, reliable connections for your applications and users.

Keep your SSL/TLS certificates up-to-date and compliant with current requirements to avoid handshake problems and ensure a secure browsing experience.