I want to secure Elasticsearch and Kibana using Search Guard 5 plugin. Search Guard SSL is bundled with Search Guard 5.
I have got three nodes cluster. One of them is master. My question is - do I have to install Search Guard 5 on every node or only on master node? And what about configuration files? Do I have to chnage config files on every node?
You need to install the Search Guard plugin on every node regardless of the node type (master, data, ingest, loadbalancer, ...).
So you also need to add the Search Guard specific configuration in elasticsearch.yml on every node. But there are only a few entries for the SSL configuration.
The main parts of the configs reside in an index within elasticsearch itself an can be administered through "sgadmin" tool from any host which can connect to elasticsearch (on transport protocol level, typically port 9300)