The user identity that Hadoop uses for permissions in HDFS is determined by running the whoami command on the client system. Similarly, the group names are derived from the output of running groups.
If, however, your Hadoop user identity is different from the name of your user account on your client machine, then you can explicitly set your Hadoop username and group names by setting the hadoop.job.ugi property. The username and group names are specified as a comma-separated list of strings.
You can set the user identity that the HDFS web interface runs as by setting dfs.web.ugi using the same syntax. By default, it is webuser,webgroup, which is not a super user, so system files are not accessible through the web interface. Notice that, by default, there is no authentication with this system.