Definition
An Intrusion Detection System (IDS) is a security tool that monitors network traffic or system activities for malicious actions or policy violations. It analyzes data for known threat signatures or deviations from normal behavior to identify potential security breaches. In practice, an IDS acts like a digital alarm system, alerting administrators when suspicious activity is detected. This is crucial for prompt incident response, minimizing damage and protecting sensitive data. For example, an IDS could flag an attempt to exploit a known software vulnerability by comparing network packets against a database of attack patterns. Unlike an Intrusion Prevention System (IPS), an IDS only detects and alerts, it does not automatically block the threat. Knowledge of IDS is essential for the CompTIA Security+, CySA+, and CISSP certifications.