WARNING:
You need to limit JAVA/HTTP access to NGINX/Reverse Proxy!
Edit :
/var/lib/openhab2/etc/org.ops4j.pax.web.cfg
and change/set these:
org.osgi.service.http.secure.enabled = false
org.ops4j.pax.web.listening.addresses = 127.0.0.1
Now openHAB2 listening only localhost (127.0.0.1):
tcp6 0 0 127.0.0.1:8101 :::* LISTEN 12731/java
tcp6 0 0 127.0.0.1:41833 :::* LISTEN 12731/java
tcp6 0 0 127.0.0.1:8081 :::* LISTEN 12731/java