I tried it all,
firewall port is opened OUT as well.
netstat -plunt shows that the app IS LISTENING ON THE PORT
no additional external firewall was ever setup.
the app is located in /var/natholepunch/Nat.exe
app is la...
Its because the .exe i was running is listening to UDP
so ALL of the port checkers online and default nmap port check will simply report it as closed
you need to perform udp check
nmap -p PORTNUMBER -sU -P0 YOURIP