Definition: An IDS (Intrusion Detection System) is a device or application used to inspect all network traffic and alert the user or administrator when there has been unauthorized attempts or access. The two primary methods of monitoring are signature-based and anomaly-based. Depending on the device or application used, the IDS can either simply alert the user or administrator or it could be set up to block specific traffic or automatically respond in some way.
Signature-based detection relies on comparison of traffic to a database containing signatures of known attack methods. Anomaly-based detection compares current network traffic to a known-good baseline to look for anything out of the ordinary. The IDS can be placed strategically on the network as a NIDS (network-based intrusion detection) which will inspect all network traffic or it can be installed on each individual system as a HIDS (host-based intrusion detection) which inspects traffic to and from that specific device only.
Also Known As: Intrusion Detection System, HIDS (Host Intrusion Detection System), NIDS (Network Intrusion Detection System)