Kibana is the so-called Front-end of your analyzing software. So it is important to be secured. I have also secured internal communication between Filebeat/Logstash to Elasticsearch, but this is a topic for another time. Let's start with securing Kibana's Front-end.
You SHOULD have either:
Simple insert the following lines in the kibana.yml and all should be working normal:
server.ssl.enabled: true <- Enable SSL/TLS server.ssl.certificate: /root/SSLCert/cert.pem <- Provide the Certificate (Public key + CA Info) server.ssl.key: /root/SSLCert/key.pem <- Provide the key file
Congrats, you have SSL/TLS connection :)