When large companies require pen testing, large-scale scanning is used. For example, for a global company, often a number of IP blocks exist as part of external internet facing. As mentioned earlier, in Chapter 2, Open Source Intelligence and Passive Reconnaissance, attackers do not have time-limitations to scan, but penetration testers do. Pen testers can engage multiple tools to perform this activity; Masscan is one of the tools that could be used to scan large-scale IP blocks to quickly analyze the target's live hosts. Masscan is installed in Kali by default. The biggest advantage of Masscan is its randomization of hosts, speed, flexibility, and compatibility. The following screenshot provides a Class C scanning network within a few seconds to complete and identify the available ports and services running on the target hosts:
