Logstash SSL handshake failure

What is Logstash SSL handshake failure

Understanding Logstash and Its Purpose

Logstash is a powerful data processing pipeline tool that ingests data from a multitude of sources, transforms it, and sends it to your desired 'stash'. It is an integral part of the Elastic Stack, commonly used for log and event data collection, processing, and forwarding. Logstash is highly versatile, supporting a wide range of input, filter, and output plugins, making it an essential tool for data analysis and visualization.

Identifying the Symptom: SSL Handshake Failure

When using Logstash, encountering an 'SSL handshake failure' can be a common issue, especially when setting up secure connections. This error typically manifests as a failure to establish a secure connection between Logstash and another service, such as Elasticsearch or a message broker. The error message might look something like this in the logs:

[ERROR][logstash.outputs.elasticsearch] SSL Handshake error: Received fatal alert: handshake_failure

Exploring the Issue: What Causes SSL Handshake Failures?

An SSL handshake failure in Logstash is often due to issues with SSL certificates or a mismatch in the SSL/TLS protocols used by the communicating parties. Here are some common causes:

Certificate Issues: The certificates might be expired, self-signed, or not trusted by the other party.Protocol Mismatch: The SSL/TLS protocols supported by Logstash and the other service do not match.Configuration Errors: Incorrect SSL settings in the Logstash configuration file.

Steps to Resolve SSL Handshake Failures

Step 1: Verify SSL Certificates

Ensure that the SSL certificates used by Logstash are valid and trusted by the other service. You can use the following command to check the certificate details:

openssl s_client -connect yourserver.com:443 -showcerts

Verify the certificate chain and expiry dates. If the certificate is self-signed, consider adding it to the trusted certificate store of the other service.

Step 2: Check Protocol Compatibility

Ensure that both Logstash and the other service support the same SSL/TLS protocols. You can specify the protocols in the Logstash configuration file using the ssl_protocols setting:

output { elasticsearch { hosts => ["https://yourserver.com:9200"] ssl => true ssl_certificate_verification => true ssl_protocols => ["TLSv1.2", "TLSv1.3"] }}

Step 3: Update Logstash Configuration

Ensure that the Logstash configuration file is correctly set up to use SSL. Here is an example configuration snippet:

output { elasticsearch { hosts => ["https://yourserver.com:9200"] ssl => true cacert => "/path/to/ca.crt" user => "elastic" password => "changeme" }}

Make sure the cacert path is correct and points to a valid CA certificate.

Additional Resources

For more detailed information on configuring SSL in Logstash, you can refer to the official Logstash SSL Configuration Guide. Additionally, understanding SSL/TLS protocols can be enhanced by visiting SSL.com's Guide to SSL/TLS Handshakes.