Enumerating hosts
Host enumeration is the process of gaining specific particulars regarding a defined host. It is not enough to know that a server or wireless access point is present; instead, we need to expand the attack surface by identifying open ports, the base operating system, services that are running, and supporting applications. This is highly intrusive and, unless care is taken, such activity will be detected and logged by the target organization.
Live host discovery
The first step is to run network ping sweeps against a target address space and look for responses that indicate that a particular target is live and capable of responding. Historically, pinging is referred to as the use of ICMP; however, TCP, UDP, ICMP, and ARP traffic can also be used to identify live hosts.
Various scanners can be run from remote locations across the internet to identify live hosts. Although the primary scanner is Nmap, Kali provides several other applications that are also useful...