Mapping Authenticated Users to Other Users
The principal.mapping parameter of an
                            identity-assertion provider determines the user name that
                        the gateway asserts (uses as the authenticated user) for grouping,
                        authorization, and to run the request on the cluster.
| ![[Note]](../common/images/admon/note.png) | Note | 
|---|---|
| If a user does not match a principal mapping definition, the authenticated user becomes the effective user. | 
To add user mapping rule to an identity-assertion provider:
- Open the cluster topology descriptor file, - $cluster-name.xml, in a text editor.
- Add a - Defaultidentity-assertion provider to- topology/gatewaywith the- principal.mappingparameter as follows:- <provider> <role>identity-assertion</role> <name>Default</name> <enabled>true</enabled> <param> <name>principal.mapping</name> <value>$user_ids=$cluster_user;$user_ids=$cluster_user1;...</value> </param> </provider>- where the value contains a semi-colon-separated list of external to internal user mappings, and the following variables match the names in your environment: - $user_ids- is a comma-separated list of external users or the wildcard (*) indicates all users. 
- $cluster_user- is the Hadoop cluster user name the gateway asserts, that is the authenticated user name. 
 
- Save the file. - The gateway creates a new WAR file with modified timestamp in - $gateway/data/deployments.

