I have a C# application that I've written that listens on port 789. It is running on a Windows XP Professional computer. Running
netstat -an | find "789"
TCP 0.0.0.0:789 0.0.0.0:0 LISTENING
When I run
nmap -A -vv ip on a different linux machine (but same subnet) it only reports other ports open on the host (i.e. mysql, vnc, etc), but not the port opened by my application.
However, when I run
nmap -p 789 ip I get:
PORT STATE SERVICE 789/tcp open unknown
Why is there a difference between the two nmap scans? Is there anything I can do to ensure that nmap detects the open port when doing a full scan?