OT Glossary

Intrusion detection system

 A security tool that monitors network or system activity for malicious or abnormal behavior and raises alerts. In ICS, an IDS often means a network intrusion detection appliance watching the control network traffic (possibly with ICS protocol awareness) to detect things like unusual commands or known malware signatures. A related tool is an IPS (intrusion prevention system) that can take some action to stop the attack in addition to alerting.