Network Intrusion Detection System (NIDS) engine
Network Intrusion Prevention System (NIPS) engine
Network Security Monitoring (NSM) engine
Off line analysis of PCAP files
Traffic recording using pcap logger
Unix socket mode for automated PCAP file processing
Advanced integration with Linux Netfilter firewalling
Multi-Platform support which includes Linux, FreeBSD, OpenBSD, Mac OS X, Windows
See official site. for full features details