Chapter 3: Network Scanning

In the information security industry, Nmap is still the de facto tool for network scanning, leaving all other scanners far behind with its cutting-edge features, such as IPv6 support, hundreds of NSE scripts, advanced configuration options, and several scanning modes. Many different ping and port scanning techniques contributed by security researchers from all around the world are built into Nmap for host and service discovery.

Hosts protected by packet filtering systems, such as firewalls or intrusion prevention systems (IPSes), may return incorrect results because of the rules blocking certain types of protocols. In these situations, Nmap shines as you can easily try different scanning techniques, or a combination of them, to bypass these restrictions and even tune your scan to make your traffic less suspicious. Learning about these different scanning techniques and how to combine them is necessary if we want to perform comprehensive scans.

System...