What does a port scanner do?

A port scanner is a specialized tool designed primarily to identify open ports on a networked device. By sending requests to specific ports, it determines whether those ports are accepting connections, thus indicating whether they are open or closed. This capability is crucial in understanding the network's security posture, as open ports can imply potential vulnerabilities or services that are running and accessible from outside networks.

Knowing which ports are open helps security professionals assess the attack surface of a system, allowing them to implement appropriate security measures. For instance, if a scanner reveals that a port associated with a particular service (like HTTP or FTP) is open, the security team can investigate whether that service is secured properly or if it requires additional hardening.

In contrast, analyzing network traffic for potential threats involves different tools and methodologies, such as intrusion detection systems, which focus on monitoring packets as they traverse the network rather than directly engaging with device ports. Similarly, monitoring log data for compliance typically refers to reviewing access logs and system logs to ensure that operational policies are being followed rather than probing network services. Lastly, performing a full system vulnerability assessment usually entails looking for various vulnerabilities across all layers of a system, which includes more comprehensive activities than simply checking the status of network ports.