I protected Kibana and elasticsearch with shield. The problem is it's only 30-day trial. Is there another way to protect Kibana and elasticsearch and how to do it?
Take a look at SearchGuard. It's opensource and free, as in free beer 
The plugin is incompatible with Elasticsearch [2.3.3]. Was designed for version [2.2.1]. So I can't use it
I am using it with ES 2.3.2. I have no idea what you are talking about
How did you install it?
search-guard is now compatible with ES 2.3.3
sudo bin/plugin install com.floragunn/search-guard-2/2.3.3.0-beta3
J.