Github user Leemoonsoo commented on the issue:
https://github.com/apache/zeppelin/pull/2986
I was thinking the cases like a (or more) firewalls, NATs between Server
and Interpreters.
And accepting range of ports on each side is more difficult to configure
than accepting a single port in one side.
But for now, Interpreter runs in the same host where Server runs. So not a
concern unless Zeppelin have ability to run Interpreter in remote machines.---
