Intrusion detectors work by monitoring network traffic or system activities for signs of malicious activity or policy violations. These systems analyze data from various sources, such as network packets, system logs, and user behavior, to detect patterns that may indicate an intrusion. When suspicious activity is identified, the system generates alerts to notify administrators, enabling them to take appropriate action to mitigate the threat.
An intrusion detection system (IDS) operates by using sensors to capture and analyze network or host-based data. These sensors can be strategically placed within a network to monitor traffic at critical points or on individual hosts to observe system-level activities. The IDS compares the captured data against predefined signatures of known threats or anomaly-based profiles that represent normal behavior. When deviations from these signatures or profiles are detected, the IDS logs the event and generates an alert for further investigation.
The principle of an intrusion detection system is based on identifying deviations from normal behavior or known threat patterns. IDSs use two main detection methods: signature-based detection and anomaly-based detection. Signature-based detection relies on a database of known attack patterns and signatures to identify malicious activity. Anomaly-based detection establishes a baseline of normal behavior and detects anomalies by identifying deviations from this baseline. The principle is to identify and respond to potential threats before they can cause significant damage.
An intrusion prevention system (IPS) works similarly to an IDS but with the added capability of actively blocking detected threats. An IPS monitors network traffic or system activities in real-time and takes immediate action when malicious activity is detected. This action can include dropping malicious packets, blocking IP addresses, or terminating suspicious connections. By combining detection and prevention capabilities, an IPS can stop attacks before they succeed, providing an additional layer of security.
The two techniques for intrusion detection are signature-based detection and anomaly-based detection. Signature-based detection involves comparing monitored activities against a database of known attack signatures to identify matches. This method is effective for detecting known threats but may struggle with new, unknown attacks. Anomaly-based detection, on the other hand, involves establishing a baseline of normal behavior and identifying deviations from this norm. This method can detect previously unknown threats but may produce false positives if normal behavior is not accurately defined. Both techniques are often used together in intrusion detection systems to provide comprehensive protection.