Snort is considered the most advanced open source intrusion prevention (IPS) system in the world. Snort IPS uses a set of rules to help define malicious network activity, and uses these rules to find matching packets and generate alerts for the user.

Snort has three main uses: as a packet sniffer like that, or as a packet logger, or it can be a full-fledged network intrusion prevention system. Snort can be downloaded and configured for personal and commercial use.
The publisher’s website:https://www.snort.org/