Introduction

In the information security industry, Nmap is the de facto tool for network exploration, leaving all other scanners far behind with its cutting-edge features, such as IPv6 scanning and advanced optimization options. It supports several different ping and port scanning techniques for host and service discovery correspondingly.

Hosts protected by packet filtering systems, such as firewalls or intrusion prevention systems, may return incorrect results when scanned because of the rules used to block certain types of network packets. In these situations, Nmap really shines as users can easily try different scanning techniques (or a combination of them) to bypass these network restrictions. In addition, it supports some options useful to make our scan traffic less suspicious. Learning about these different scanning techniques and how to combine them is necessary if we want to perform very comprehensive scans.

System administrators will gain an understanding of the inner workings of...