Zeppelin Impersonation giving InterpreterException

[#1]

I have created a user for Zeppelin using basic authentication in Ambari (Shiro):

[users]
user1 = abc123456, datascience

[roles]
datascience = *

Then I created the same user-role in Ranger, using the UI.

Then in Zeppelin, logged as that user, I create a notebook which uses a Hive interpreter with impersonation. When I launch the query:

logged_in_user()

I get the following exception:

Host key verification failed.

	at org.apache.zeppelin.interpreter.remote.RemoteInterpreterManagedProcess.start(RemoteInterpreterManagedProcess.java:154)
	at org.apache.zeppelin.interpreter.remote.RemoteInterpreterProcess.reference(RemoteInterpreterProcess.java:73)
	at org.apache.zeppelin.interpreter.remote.RemoteInterpreter.open(RemoteInterpreter.java:292)
	at org.apache.zeppelin.interpreter.remote.RemoteInterpreter.getFormType(RemoteInterpreter.java:457)
	at org.apache.zeppelin.interpreter.LazyOpenInterpreter.getFormType(LazyOpenInterpreter.java:115)
	at org.apache.zeppelin.notebook.Paragraph.jobRun(Paragraph.java:391)
	at org.apache.zeppelin.scheduler.Job.run(Job.java:175)
	at org.apache.zeppelin.scheduler.RemoteScheduler$JobRunner.run(RemoteScheduler.java:329)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

What am I doing wrong?

[#2]

when you use impersonation you must have system users created in the OS with the same name which you have in zeppelin shiro.ini (user1 in your case)

[#3]

Following this thread.

Also facing this kind of error on our cluster. We did not experience this on our dev env.

All users/accounts are available to all nodes across cluster.

BTW, I'm using PAM auth module for user-impersonation.