In Hadoop how is security achieved?
In HDP and HDF you have option to Kerberized all components + integrate with Active Directory or other directory managers like (freeIPA or openldap) for authorization.
Authentication and auditing part goes to apache Ranger.
If required encruption Ranger KMS and Apache Knox for perimiter security.
Apache Hadoop achieves security by using Kerberos.
At a high level, there are three steps that a client must take to access a service when using Kerberos. Thus, each of which involves a message exchange with a server.