What are the two main types of Intrusion Detection Systems?

The identification of the two main types of Intrusion Detection Systems as network-based and host-based is grounded in their core functions and architectural differences.

Network-based Intrusion Detection Systems (NIDS) monitor traffic that traverses a network, analyzing data packets for signs of malicious activity. They are positioned at strategic points within the network to capture and inspect traffic in real-time, allowing organizations to detect a wide range of attacks that may originate from various sources.

On the other hand, Host-based Intrusion Detection Systems (HIDS) are installed on individual devices or hosts. They focus on monitoring the behavior and activities of the specific system they are installed on, checking for signs of unauthorized access, anomalous behavior, or policy violations. HIDS provides detailed information about what is happening on a device, which can include system calls, file modifications, and application activities.

This fundamental distinction between how these systems operate and where they are deployed is critical for understanding intrusion detection strategies. Both types serve complementary roles in an organization's security posture, enabling comprehensive surveillance across both network layers and individual endpoints.