Definition
Port scanning is a technique used to discover open ports and services running on a network device. Attackers use it to find potential entry points into a system, while defenders use it to identify unauthorized services or misconfigurations. The process involves sending specially crafted packets to a range of port numbers on a target host and analyzing the responses received. Understanding open ports is crucial for network security, as each open port represents a potential vulnerability. For instance, an administrator might scan a web server to ensure only the expected ports for HTTP and HTTPS are open, not unexpected administrative ports. It differs from network scanning, which typically focuses on identifying active hosts rather than specific service ports. Port scanning is a fundamental concept covered in cybersecurity certifications like CompTIA Security+ and CySA+.