> For the complete documentation index, see [llms.txt](https://docs.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pentaho.com/pdia-admin/9.3-administer/secure-the-pentaho-system/big-data-security/kerberos-authentication-versus-secure-impersonation.md).

# Kerberos authentication versus secure impersonation

Kerberos authentication occurs when Pentaho users connect to a Hadoop cluster with a default Kerberos principal. All the Pentaho users connect to the Hadoop cluster with the same Kerberos principal.

In secure impersonation, users connect to the Hadoop cluster as a proxy user. The Pentaho user ID matches the cluster user ID in a one-on-one mapping, and resources are accessed and processes are executed as the cluster user.

Secure impersonation occurs when:

1. pre-defined credentials authenticate to a Kerberos server before connecting to the Hadoop cluster,
2. the Pentaho Server is configured for secure impersonation, and
3. the Hadoop cluster is secured.


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