An anomaly-based intrusion detection system (IDS) operates by gathering data on:

An anomaly-based intrusion detection system (IDS) operates by gathering data on normal network behavior and using it as a baseline for measuring abnormal activity. This is important because it allows the IDS to detect any activity that is outside of the normal range of usage for the network, which can help to identify potential malicious activity or security threats. Additionally, the IDS will monitor for any changes in the baseline behavior and alert the administrator if any irregularities are detected. By contrast, signature-based IDSs operate by gathering attack pattern signatures from historical data and comparing them against incoming traffic in order to identify malicious activity.