SELKS is a free and open source Debian (with LXDE X-window manager) based IDS/IPS platform released under GPLv3 from Stamus Networks (https://www.stamus-networks.com/).
Suricata is a high performance Network IDS, IPS and Network Security Monitoring engine. Open Source and owned by a community run non-profit foundation, the Open Information Security Foundation (OISF). Suricata is developed by the OISF and its supporting vendors.
pfsense fork - Your next Open Source Firewall !
Secure Your Network with ease.
From Virtual Private Networking to Intrusion Detection, Best in class, FREE Open Source Project.