Make sure Hadoop is installed, configured and setup correctly. For more information see: * Single Node Setup for first-time users. * Cluster Setup for large, distributed clusters.
Service Level Authorization is the initial authorization mechanism to ensure clients connecting to a particular Hadoop service have the necessary, pre-configured, permissions and are authorized to access the given service. For example, a MapReduce cluster can use this mechanism to allow a configured list of users/groups to submit jobs.
The $HADOOP_CONF_DIR/hadoop-policy.xml configuration file is used to define the access control lists for various Hadoop services.
Service Level Authorization is performed much before to other access control checks such as file-permission checks, access control on job queues etc.
This section describes how to configure service-level authorization via the configuration file $HADOOP_CONF_DIR/hadoop-policy.xml.
By default, service-level authorization is disabled for Hadoop. To enable it set the configuration property hadoop.security.authorization to true in $HADOOP_CONF_DIR/core-site.xml.
This section lists the various Hadoop services and their configuration knobs:
| Property | Service |
|---|---|
| security.client.protocol.acl | ACL for ClientProtocol, which is used by user code via the DistributedFileSystem. |
| security.client.datanode.protocol.acl | ACL for ClientDatanodeProtocol, the client-to-datanode protocol for block recovery. |
| security.datanode.protocol.acl | ACL for DatanodeProtocol, which is used by datanodes to communicate with the namenode. |
| security.inter.datanode.protocol.acl | ACL for InterDatanodeProtocol, the inter-datanode protocol for updating generation timestamp. |
| security.namenode.protocol.acl | ACL for NamenodeProtocol, the protocol used by the secondary namenode to communicate with the namenode. |
| security.inter.tracker.protocol.acl | ACL for InterTrackerProtocol, used by the tasktrackers to communicate with the jobtracker. |
| security.job.submission.protocol.acl | ACL for JobSubmissionProtocol, used by job clients to communciate with the jobtracker for job submission, querying job status etc. |
| security.task.umbilical.protocol.acl | ACL for TaskUmbilicalProtocol, used by the map and reduce tasks to communicate with the parent tasktracker. |
| security.refresh.policy.protocol.acl | ACL for RefreshAuthorizationPolicyProtocol, used by the dfsadmin and mradmin commands to refresh the security policy in-effect. |
| security.ha.service.protocol.acl | ACL for HAService protocol used by HAAdmin to manage the active and stand-by states of namenode. |
$HADOOP_CONF_DIR/hadoop-policy.xml defines an access control list for each Hadoop service. Every access control list has a simple format:
The list of users and groups are both comma separated list of names. The two lists are separated by a space.
Example: user1,user2 group1,group2.
Add a blank at the beginning of the line if only a list of groups is to be provided, equivalently a comman-separated list of users followed by a space or nothing implies only a set of given users.
A special value of * implies that all users are allowed to access the service.
The service-level authorization configuration for the NameNode and JobTracker can be changed without restarting either of the Hadoop master daemons. The cluster administrator can change $HADOOP_CONF_DIR/hadoop-policy.xml on the master nodes and instruct the NameNode and JobTracker to reload their respective configurations via the -refreshServiceAcl switch to dfsadmin and mradmin commands respectively.
Refresh the service-level authorization configuration for the NameNode:
$ bin/hadoop dfsadmin -refreshServiceAcl
Refresh the service-level authorization configuration for the JobTracker:
$ bin/hadoop mradmin -refreshServiceAcl
Of course, one can use the security.refresh.policy.protocol.acl property in $HADOOP_CONF_DIR/hadoop-policy.xml to restrict access to the ability to refresh the service-level authorization configuration to certain users/groups.
Allow only users alice, bob and users in the mapreduce group to submit jobs to the MapReduce cluster:
<property>
<name>security.job.submission.protocol.acl</name>
<value>alice,bob mapreduce</value>
</property>Allow only DataNodes running as the users who belong to the group datanodes to communicate with the NameNode:
<property>
<name>security.datanode.protocol.acl</name>
<value>datanodes</value>
</property>Allow any user to talk to the HDFS cluster as a DFSClient:
<property>
<name>security.client.protocol.acl</name>
<value>*</value>
</property>