To audit all the users who log into the Hunk Search Head, see this answer: https://answers.splunk.com/answers/225682/how-to-search-splunks-internal-audit-events-to-see.html
From a Hadoop point of view, all of Splunk Users run the MapReduce job as the user who installed Splunk, so that should be in the Hadoop log. You can use this Splunk App to log the Hadoop logs: https://splunkbase.splunk.com/app/3134/
To audit all the users who log into the Hunk Search Head, see this answer: https://answers.splunk.com/answers/225682/how-to-search-splunks-internal-audit-events-to-see.html
From a Hadoop point of view, all of Splunk Users run the MapReduce job as the user who installed Splunk, so that should be in the Hadoop log. You can use this Splunk App to log the Hadoop logs: https://splunkbase.splunk.com/app/3134/
Much appreciated!!!