Debian Stretch 9 Test if Port is Open
You are Welcome! This Tip Shows You How to List Open Ports in Debian Stretch 9 GNU/Linux.
And the Debian Stretch 9 Check if Port is Open is achieved by the Nmap Network Tool.
Finally, Nmap (Network Mapper) is a Security Scanner, originally written by Gordon Lyon (also known by his pseudonym Fyodor Vaskovich), used to discover hosts and services on a computer network, thus building a “Map” of the network.
1. Opening Shell Session
Open a Shell Terminal emulator window
(Press “Enter” to Execute Commands)
2. Installing Nmap
Then Install Nmap Tool with:
sudo apt install nmap
3. Listing Open Ports
Finally, to List All Open Ports
sudo nmap -sT -O localhost
And in the Output you should find a detailed List of the Open Ports: