title: AWS EMR kerberizing the cluster hadoop.security.AccessControlException
body: <p>I am trying to kerberize the AWS EMR cluster. I have enabled hadoop security, created the kerberos principals and deployed them on all the nodes. </p>
  
  <p>However, when I start the namenode using the command 'sudo start hadoop-hdfs-namenode' following exception is thrown. </p>
  
  <blockquote>
    <p>2016-06-08 06:14:06,515 INFO org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor (main): Number of failed storage changes from 0 to 0
    2016-06-08 06:14:06,515 INFO org.apache.hadoop.hdfs.security.token.block.BlockTokenSecretManager (org.apache.hadoop.hdfs.server.blockmanagement.HeartbeatManager$Monitor@ac4860): Updating block keys
    2016-06-08 06:14:06,544 INFO org.apache.hadoop.ipc.Server (IPC Server Responder): IPC Server Responder: starting
    2016-06-08 06:14:06,544 INFO org.apache.hadoop.ipc.Server (IPC Server listener on 8020): IPC Server listener on 8020: starting
    2016-06-08 06:14:06,560 INFO org.apache.hadoop.hdfs.server.namenode.NameNode (main): NameNode RPC up at: ip-172-31-21-213.ap-southeast-1.compute.internal/172.31.21.213:8020
    2016-06-08 06:14:06,560 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem (main): Starting services required for active state
    2016-06-08 06:14:06,564 INFO org.apache.hadoop.hdfs.server.blockmanagement.CacheReplicationMonitor (CacheReplicationMonitor(443740501)): Starting CacheReplicationMonitor with interval 30000 milliseconds
    2016-06-08 06:14:06,763 INFO org.apache.hadoop.ipc.Server (Socket Reader #1 for port 8020): Socket Reader #1 for port 8020: readAndProcess from client 172.31.21.213 threw exception [org.apache.hadoop.security.AccessControlException: SIMPLE authentication is not enabled.  Available:[TOKEN, KERBEROS]]
    org.apache.hadoop.security.AccessControlException: SIMPLE authentication is not enabled.  Available:[TOKEN, KERBEROS]
            at org.apache.hadoop.ipc.Server$Connection.initializeAuthContext(Server.java:1564)
            at org.apache.hadoop.ipc.Server$Connection.readAndProcess(Server.java:1520)
            at org.apache.hadoop.ipc.Server$Listener.doRead(Server.java:771)
            at org.apache.hadoop.ipc.Server$Listener$Reader.doRunLoop(Server.java:637)
            at org.apache.hadoop.ipc.Server$Listener$Reader.run(Server.java:608)</p>
  </blockquote>
  
  <p>Kindly help me in this regard. Thanks in advance.</p>