What is the purpose of spnego.service.keytab in a secure hadoop cluster

[#1]

What is the purpose of spnego.service.keytab in a secure hadoop cluster

[#2]

@Tech Gig

That is used by components like "NameNode", "SecondaryNameNode" , "MR2 History Server", "Oozie", "WebHCat" ...etc and other other components listed in the following doc to provide a secure http access to various HTTP based resources like UI.

https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.4.2/bk_Security_Guide/content/creating_service_...

- By default, access to the HTTP-based services and UI’s for the cluster are not configured to require authentication. Kerberos authentication can be configured for the Web UIs for HDFS, YARN, MapReduce2, HBase, Oozie, Falcon and Storm.

Following link provides more details about the same:

http://docs.hortonworks.com/HDPDocuments/Ambari-2.5.0.3/bk_ambari-security/content/configuring_http_...

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