HTTP Status Code 525 – SSL Handshake Failed

The HTTP status code 525 SSL Handshake Failed indicates that the server was unable to establish a secure connection with the client over SSL/TLS. This error occurs when the SSL handshake, which is the process of initiating a secure SSL/TLS connection, fails. The failure can result from various issues such as misconfigured SSL certificates, incompatible cipher suites, or network problems.

Example 1: Misconfigured SSL Certificates

In this example, a server is configured with an expired SSL certificate, which leads to a failed SSL handshake when a client attempts to connect securely.

    Server Configuration:
    - SSL Certificate: Expired

    Client Request:
    GET / HTTP/1.1
    Host: example.com
    Connection: keep-alive
    

Explanation: When the client sends a request to example.com, the server attempts to establish an SSL connection. However, since the certificate has expired, the SSL handshake cannot be completed, resulting in a 525 error.

Example 2: Incompatible Cipher Suites

Here, a server and client attempt to communicate, but they do not share any compatible cipher suites, leading to the SSL handshake failure.

    Server Configuration:
    - Supported Cipher Suites: [TLS_AES_128_GCM_SHA256]

    Client Configuration:
    - Supported Cipher Suites: [TLS_RSA_WITH_AES_128_CBC_SHA]

    Client Request:
    GET / HTTP/1.1
    Host: example.com
    Connection: keep-alive
    

Explanation: The client and server cannot agree on a common cipher suite to use for the connection. The server supports only TLS_AES_128_GCM_SHA256, while the client only supports TLS_RSA_WITH_AES_128_CBC_SHA. Without a shared cipher suite, the SSL handshake cannot succeed, and a 525 error is returned.

Example 3 Scenario

# Client sends a request example.
GET /example HTTP/1.1
Host: www.example.com

# Server Response
HTTP/1.1 525 525 SSL Handshake Failed
Date: Wed, 09 Oct 2024 23:13:50 GMT
Server: ExampleServer/1.0
Content-Type: application/json

{
    "error": "Description of the error for 525"
}

Example 4 Scenario

# Client sends another example request.
POST /another-example HTTP/1.1
Host: www.example.com

# Server Response
HTTP/1.1 525 525 SSL Handshake Failed
Date: Wed, 09 Oct 2024 23:13:50 GMT
Server: ExampleServer/1.0
Content-Type: application/json

{
    "error": "Detailed message for 525"
}

Summary

HTTP status code 525 is a server-side error indicating that the SSL/TLS handshake has failed. This handshake is crucial for establishing a secure connection between a client and server. Common causes of this error include expired or misconfigured SSL certificates, incompatible cipher suites, or network issues. To resolve a 525 error, ensure that SSL certificates are valid, properly configured, and that both client and server support compatible cipher suites.