Nmap is a port scanner that is available for all operating systems. It is most often used from the text console, although a graphical user interface exists, so even novices can use it.
The Nmap tool is used in active reconnaissance in order to not only determine live systems, but also determine the holes in systems.
Nmap is one of the best tools in the hacking community and is well supported.
1: How To Use Nmap
2: Introduction to Scanning
3: Introduction to Nmap
4: NMap for Windows – Installation Guide
5: NMap for Windows – Basic Scanning Techniques
6: NMap for Windows – Scanning Multiple Systems
7: NMap for Windows – Scanning a Web Address
8: NMap for Windows – Advanced Scanning Techniques