Tell about my experience of the Linux networking tools such as nmap, remind me how to know which ports are open on the system that we use in order for the security system. At this time I will give a tutorial very simpler and shorter. This tutorial on how to determine what ports are open on the system using the tools that we use nmap on linux.
First, you must know in advance how to use nmap device (network mapping). simple enough to use, just need to do a bit of a soft touch on your linux to run on linux terminal and type the command "nmap --h" function to the calling function help on nmap.
Then you can directly execute the nmap part if you want to check what ports are open on a system that you use other people or systems to use. Previously, you had to know what you do, if you want to do your own checks on computers or systems you use, just type the command "nmap localhost".
Well, then if you want to see which ports are open on other people's computers, first of all you should know that the internet protocol that is used by the system, if you already know the ip-address on a computer system to others, then type the command "nmap IP -COMPUTER ", in this case I want to see my router system. It can be seen that any open ports on my router's system. For example, as depicted in the image below!
For more details, can be seen through the following youtube channel!