1
SNORT
Snort- Network Intrusion Detection & Prevention System
https://www.snort.org/
2
Suricata| Open Source IDS / IPS / NSM engine
Suricata is a free and open source, mature, fast and robust network threat detection engine.
The Suricata engine is capable of real time intrusion detection
(IDS), inline intrusion prevention (IPS), network security monitoring
(NSM) and offline pcap processing.
https://suricata-ids.org/