Exploring scanning techniques
There are several scans and scan types that can be performed, including a port scan, a host scan, and even a vulnerability scan, but before we get into that, let’s look at the most basic ways to determine whether a machine is on a network and reachable. One of the first ways to determine whether a machine is reachable is to use the built-in utilities of ping and Traceroute that are included with most operating systems.
Ping
Network engineers learned long ago they needed a way to determine whether remote systems were online. They created the Internet Control Message Protocol (ICMP) as a means to support network troubleshooting. At the core of the ICMP protocol is the utility called Ping. There are several functions of ping; however, the primary ones that most are familiar with are ICMP_ECHO_REQUEST, also known as Type 8, and ICMP_ECHO_REPLY, also known as Type 0. Ping is a very simple utility that can be run by using the ping command, followed...