Linux

Code:

netstat -pnae | grep -i vnc

Typically a VNC server opens the next 3 available TCP/IP ports, starting from 5801, 5901, and 6001 respectively. Port 5801 is for VNC client connection over HTTP protocol, port 5901 is for VNC client connection over RFB protocol, and port 6001 is to allows X applications to connect to the VNC server.

Executing vncserver for the second time or executing the vncserver :2 command, will startup a VNC server that binds and listens to port 5802, 5902, and 6002 respectively, and so on.

Use lsof or netstat to show the network ports opened by a vnc server.

You can always look at nomachine.

NoMachine NX - Terminal Server, Desktop Virtualization and Access Management Software

The free version works really well.

Also make sure that the firewall (iptables) is allowing the connection through!