CrowdSec is an open-source and lightweight software that allows you to detect peers with malevolent behaviors and block them from accessing your systems at various level (infrastructural, system, applicative).

To achieve this, CrowdSec reads logs from different sources (files, streams ...) to parse, normalize and enrich them before matching them to threats patterns called scenarios.

CrowdSec is a modular and plug-able framework, it ships a large variety of well known popular scenarios; users can choose what scenarios they want to be protected from as well as easily adding new custom ones to better fit their environment.

Detected malevolent peers can then be prevented from accessing your resources by deploying bouncers at various levels (applicative, system, infrastructural) of your stack.

One of the advantages of Crowdsec when compared to other solutions is its crowd-sourced aspect : Meta information about detected attacks (source IP, time and triggered scenario) are sent to a central API and then shared amongst all users.

Thanks to this, besides detecting and stopping attacks in real time based on your logs, it allows you to preemptively block known bad actors from accessing your information system.

https://doc.crowdsec.net/docs/intro/