
1. A Swiss army knife
Not for nothing is Nmap referred to as the »Swiss Army Knife« among the port scanners among administrators, security researchers, and IT geeks. The tool has been developed since 1997 and serves as a tool for finding open ports/network services of a system.
In addition to pure port scanning, the Open Source Tool ( GNU License ) can do even more. Among other things, Nmap can use OS fingerprinting to recognize the operating system used on the destination host or to identify all active hosts in a network via mapping.
In this article, I would like to give you a brief look at Nmap and show you how you can check your (server) system for open ports. However, the tool is very comprehensive and powerful, which is why I will only go into a few basic functions.