Ranger User Guide
Also available as:

HDP Security Features

HDP uses Apache Ranger to provide centralized security administration and managemtent. The Ranger Administration Portal is the central interface for security administration. Users can create and update policies, which are then stored in a policy database. Ranger plugins (light-weight Java programs) are embedded within the processes of each cluster component. For example, the Ranger plugin for Apache Hive is embedded within Hiveserver2.

Apache Ranger Architecture

These plugins pull policies from a central server and store them locally in a file. When a user request comes through the component, these plugins intercept the request and evaluate it against the security policy. Plugins also collect data from the user request and follow a separate thread to send this data back to the audit server.