Nmap$-$Zenmap GUI is a utility used to scan hosts for open ports in various ways. Remember that client hosts will use many ephemeral ports for each session to talk to standard ports, i$.$e$.,$ the agreed$-$upon ports on which various applications are running.$$A port scanning utility will go out to hosts and try multiple ports to see which ports answer. It is like knocking on doors to see which houses are open. Nmap will try many registered ports and$$report back which ones responded. This is very useful for attackers to enumerate the process of finding information. In this case, we are looking for what is known as $$open ports.$$ Nmap will even go further and report back additional information that the application might provide