This tutorial understands how to find open ports on a router. Ports on a remote router can be detected using a port scanning tools like nmap. Port scanning is a technique which is used to find ports open on a remote device.
In the below setup, the PC and the router are on the same network. The IP address of the router is 192.168.0.1. This demonstration can also be used when the PC and the router are on different networks.
Download and install the GUI version of nmap which is ZENMAP from nmap.org on your PC.
The screenshot of ZENMAP is shown below. Perform a port scan from the PC to the IP address of the router which is 192.168.0.1. Quick scan is selected in this case as shown below.
The scan returns the ports which are open on the router. It can be observed that telnet and http ports are opened on the router.