What does a Network-Based IDS (NIDS) monitor?

A Network-Based IDS (NIDS) is designed to monitor network traffic as it passes through various segments of the network. Its primary function is to analyze incoming and outgoing data packets for signs of malicious activity or security breaches, thereby providing an overview of the network’s overall security posture. By deploying sensors at key locations across the network infrastructure, a NIDS can detect threats, such as unauthorized access attempts, malware communications, or unusual patterns that might signify an attack.

Monitoring traffic on a network segment allows the NIDS to correlate activities from multiple devices, offering insights that are not possible by analyzing traffic from a singular device. This holistic view is crucial for identifying sophisticated attacks that might span multiple endpoints or require a broader contextual understanding of the network traffic. By focusing on segment traffic, NIDS contributes effectively to an organization's defense strategy by alerting administrators to potential vulnerabilities and breaches in real-time.