In the interest of platform stability, Nagios Log Server uses previous versions of ELK software which may not conform to the default documentation that you reach from a search engine.
As of Nagios Log Server 2.1, here are the documentation links for the correct versions of the backend software:
Elasticsearch (v1.7.6):
https://www.elastic.co/guide/en/elasticsearch/reference/1.7/docs.html
Logstash (v2.4.1):
https://www.elastic.co/guide/en/logstash/2.4/index.html
Kibana (v3.0):
https://www.elastic.co/guide/en/kibana/3.0/index.html
Article ID: 859
Created On: Wed, Sep 18, 2019 at 3:06 PM
Last Updated On: Wed, Sep 18, 2019 at 3:10 PM
Authored by: swolf
Online URL: https://support.nagios.com/kb/article/nagios-log-server-elk-documentation-859.html