Authentication is a process that requires users and services to prove their identity when trying to access a system resource. Organizations typically manage user identity and authentication through various time-tested technologies, including Lightweight Directory Access Protocol (LDAP) for identity, directory, and other services, such as group management, and Kerberos for authentication.

Cloudera clusters support integration with both of these technologies. For example, organizations with existing LDAP directory services such as Active Directory (included in Microsoft Windows Server as part of its suite of Active Directory Services) can leverage the organization's existing user accounts and group listings instead of creating new accounts throughout the cluster. Using an external system such as Active Directory or OpenLDAP is required to support the user role authorization mechanism implemented in Cloudera Navigator.

For authentication, Cloudera supports integration with MIT Kerberos and with Active Directory. Microsoft Active Directory supports Kerberos for authentication in addition to its identity management and directory functionality, that is, LDAP.

Kerberos provides strong authentication, strong meaning that cryptographic mechanisms—rather than passwords alone—are used in the exchange between requesting process and service during the authentication process.

These systems are not mutually exclusive. For example, Microsoft Active Directory is an LDAP directory service that also provides Kerberos authentication services, and Kerberos credentials can be stored and managed in an LDAP directory service. Cloudera Manager Server, CDH nodes, and Cloudera Enterprise components, such as Cloudera Navigator, Apache Hive, Hue, and Impala, can all make use of Kerberos authentication.

Configuring the cluster to use Kerberos requires having administrator privileges—and access to—the Kerberos server Key Distribution Center (KDC). The process may require debugging issues between the Cloudera Manager cluster and the KDC.

On each host operating system underlying each node in a cluster, local Linux user:group accounts are created during installation of Cloudera Server and CDH services. To apply per-node authentication and authorization mechanism consistently across all the nodes of a cluster, local user:group accounts are mapped to user accounts and groups in an LDAP-compliant directory service, such as Active Directory or OpenLDAP. See Configuring LDAP Group Mappings for details.

To facilitate the authentication process from each host system (node in the cluster) to the LDAP directory, Cloudera recommends using additional software mechanisms such as SSSD (Systems Security Services Daemon) or Centrify Server Suite. See the Centrify guide Identity and Access management for Cloudera for details.