A port scan is a method for discovering which ports are open on a machine or network. To test whether someone is at home before knocking on the door, you could port scan the system or network. It reveals which ports are open and accepting information, as well as shows if firewalls are installed between the source and target. Fingerprinting is the term used to describe this technique. As a result, it can also be an ideal reconnaissance tool for attackers seeking to discover a network’s weakest point of entry. It is also used to test network security and the firewall's strength. Port scanning is a standard technique employed by hackers to discover open doors or weak spots in a network. A port scan attack may help cyber criminals discover available ports and determine whether they are sending or receiving data. It may also reveal whether security systems like firewalls are being used by a company. When hackers contact a port, the response they receive determines whether the port is being used and whether potential vulnerabilities exist. A business may also scan ports using this technique and analyze the response for potential vulnerabilities. They may then employ tools like IP scanner, network scanner (Nmap), and Netcat to ensure the security of their network and systems.