Virtual Network Computing (VNC) is a protocol used mainly for remote access and administration. The VNC service by default runs on port 5900. We can use the Nmap syntax, as follows, to enumerate VNC service:
nmap -p 5900 -T4 -A -v <Target IP address>
The following screenshot shows the output of the VNC enumeration command we executed. It tells us that the target is running VNC with protocol version 3.3:
