The Splunk Enterprise Security and Encryption documentation specifies that the primary mechanism for securing data in motion within a Splunk environment is to enable TLS/SSL encryption between forwarders and indexers. This ensures that log data transmitted from Universal Forwarders or Heavy Forwarders to Indexers is fully encrypted and protected from interception or tampering.
The correct configuration involves setting up signed SSL certificates on both forwarders and indexers:
On the forwarder, TLS settings are defined in outputs.conf, specifying parameters like sslCertPath, sslPassword, and sslRootCAPath.
On the indexer, TLS is enabled in inputs.conf and server.conf using the same shared CA for validation.
Splunk’s documentation explicitly states that this configuration protects data-in-transit between the collection (forwarder) and indexing (storage) tiers — which is the critical link where sensitive log data is most vulnerable.
Other communication channels (e.g., deployment server to clients or browser to Splunk Web) can also use encryption but do not secure the ingestion pipeline that handles the indexed data stream. Therefore, TLS should be implemented between Splunk forwarders and indexers.
References (Splunk Enterprise Documentation):
• Securing Data in Transit with SSL/TLS
• Configure Forwarder-to-Indexer Encryption Using SSL Certificates
• Server and Forwarder Authentication Setup Guide
• Splunk Enterprise Admin Manual – Security and Encryption Best Practices
