The security features in CDH 5 enable Hadoop to prevent malicious user impersonation. The Hadoop daemons leverage Kerberos to perform user authentication on all remote procedure calls (RPCs). Group resolution is performed on the Hadoop master nodes, NameNode, JobTracker and ResourceManager to guarantee that group membership cannot be manipulated by users. Map tasks are run under the user account of the user who submitted the job, ensuring isolation there. In addition to these features, new authorization mechanisms have been introduced to HDFS and MapReduce to enable more control over user access to data.

The security features in CDH 5 meet the needs of most Hadoop customers because typically the cluster is accessible only to trusted personnel. In particular, Hadoop's current threat model assumes that users cannot:

1. Have root access to cluster machines.
2. Have root access to shared client machines.
3. Read or modify packets on the network of the cluster.

Continue reading:

• Enabling Kerberos Authentication for Hadoop Using the Command Line
• FUSE Kerberos Configuration
• Using kadmin to Create Kerberos Keytab Files
• Hadoop Users (user:group) and Kerberos Principals
• Mapping Kerberos Principals to Short Names