Authentication is the mechanism to ensure that only specified hosts and users can connect to Impala. It also verifies that when clients connect to Impala, they are connected to a legitimate server. This feature prevents spoofing such as impersonation (setting up a phony client system with the same account and group names as a legitimate user) and man-in-the-middle attacks (intercepting application requests before they reach Impala and eavesdropping on sensitive information in the requests or the results).
Impala supports authentication using either Kerberos or LDAP.
Once you are finished setting up authentication, move on to authorization, which involves specifying what databases, tables, HDFS directories, and so on can be accessed by particular users when they connect through Impala. See Enabling Sentry Authorization for Impala for details.