Wikipedia
An intrusion detection system (IDS) is a device, or software application that monitors a network or systems for malicious activity or policy violations Any intrusion activity or violation is typically reported either to an administrator or collected centrally using a security information and event management (SIEM) system A SIEM system combines outputs from multiple sources and uses alarm filtering techniques to distinguish malicious activity from false alarmsIDS types range in scope from single computers to large networks The most common classifications are network intrusion detection systems (NIDS) and host-based intrusion detection systems (HIDS) A system that monitors important operating system files is an example of an HIDS, while a system that analyzes incoming network traffic is an example of an NIDS
Intrusion detection system - Wikipedia, the free encyclopedia