I have a question related to the concept of port number and its associated service.
Given that a port number is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server (example: web server is supposed to be found on port 80 also 8080...etc)
My question in a nutshell:
if nmap scan shows:
====================================== host: 10.0.xxx.xx port state service reason 20000 open dnp syn-ack ttl 56 ======================================
am I right in thinking that I have actually found a SCADA system? (DNP3 as a Distributed Network Protocol is used by SCADA Master Stations)
Well, My own opinion is yes!...but unfortunately once I got in touch with the server's owner he told me that I am completely wrong since he installed a java based application which uses port 20000 (https://babelfish.arc.nasa.gov/trac/jpf/wiki/user/output)
Am I right in saying that the guy should have chosen another port, since port 20000 is considered to be the official port number for DNP protocol (https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers)?
Thanks a lot