Intrusion Detection Systems (IDS) are tools that use signatures or rules to monitor and analyze network or systems for malicious activity or policy violations. Some of the functions of an IDS include but not limited to the detection of malicious activity, network traffic monitoring, alerting and notification, policy enforcement, incident response, etc.

Suricata is an open-source IDS developed by the Open Information Security Foundation (OISF) and could also function as an intrusion prevention system (IPS) and Network Security Monitoring (NSM).

Watch this tutorial on how to install and configure Suricata for use as an IDS and IPS:

https://www.youtube.com/watch?v=8Q3Nhyvh-1I&t=9s