Find custom SSH port number
 Art of Port Scanning — namp
We can find custom SSH port number using nmap:
command:
 nmap -P0 -T4 -sV -p- “IP address”
          -PO[protocol list]: IP Protocol Ping
          -T<0-5>: Set timing template (higher is faster). By default it will be in milliseconds.
          -sV: Probe open ports to determine service/version info
          -p
