Free UTM appliance: firewall, VPN, WAF and antivirus in one ISO.
Next Generation Open Source Firewall
Xplico is a Network Forensic Analysis Tool (NFAT)
PCAP from another point of view
Open source voucher management / hotspot system
NfSen plugin to generate and analyze per-IP statistics
network control and reporting
Dashboard of network top-talkers using netflow sources
Network Intrusion Detection and Full Packet Capture System