Snort

Snort can be deployed inline to stop these packets, as well. Snort has three primary uses: As a packet sniffer like tcpdump, as a packet logger — which is useful for network traffic debugging, or it can be used as a full-blown network intrusion prevention system. Snort can be downloaded and configured for personal and business use alike.

SNORT Intrusion Prevention System, the world's foremost open source IPS, has officially launched Snort 3, a sweeping upgrade featuring improvements and new features resulting in enhanced performance, faster processing, improved scalability for your network and a range of 200+ plugins so users can create a custom set-up for their network.

Network security system that helps businesses monitor networks, detect threats and manage responses. Snort is an open source IPS (Intrusion Prevention System) which uses a series of rules and patters to help detect threats and malicious activity on the network.