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CrowdSec

by CrowdSec · Platform · also known as CrowdSec Security Engine

Open-source behavior-based intrusion prevention engine whose detections feed a crowd-sourced IP reputation network, with remediation components for firewalls, proxies and CDNs

MIT licenseOpen sourceFreemiumPaidEnterpriseSelf-hostedCloudSelf-hostable
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Link verified Nov 2, 2026

Overview

CrowdSec is an intrusion prevention system from the company of the same name. Its Security Engine, open source under the MIT license and written in Go, parses logs or network data, evaluates them against scenarios (brute force, scanning, HTTP exploits, bot patterns) and raises decisions such as bans. Separate remediation components, formerly called bouncers, enforce those decisions in iptables or nftables, NGINX, Traefik, Caddy, HAProxy, Cloudflare, AWS WAF and other integration points.

The distinguishing element is the crowd: engines that opt in share signals about aggressive IPs with CrowdSec's central API and receive a community blocklist in return, so a server benefits from attacks seen elsewhere before it is targeted. A hosted console displays alerts across engines and offers additional curated blocklists and threat-intelligence lookups on free and paid plans.

CrowdSec runs on Linux, FreeBSD, Windows and in containers, and replaces Fail2Ban for many users. It has more moving parts than Fail2Ban, scenario tuning takes time, and the shared-intelligence features depend on the vendor's service.

Capabilities

  • Log and network parsing with scenario-based detection written in YAML
  • Remediation components for firewalls, reverse proxies, CDNs and cloud WAFs
  • Crowd-sourced community blocklist exchanged through the central API
  • Hub of parsers, scenarios and collections for common services
  • Hosted console with alert visualization and additional blocklists
  • Local API for multi-machine deployments

Typical workflows

  1. Protect SSH and web services on a VPS with firewall remediation
  2. Block attackers at a Traefik or Caddy proxy before they reach applications
  3. Subscribe to curated blocklists for a fleet through the console

Strengths

  • MIT-licensed engine with shared threat intelligence
  • Wide set of remediation integrations
  • Behavior scenarios beyond simple failed-login counting

Limitations

  • More components to install and tune than Fail2Ban
  • Community and premium blocklists depend on the vendor's service
  • Console features are tiered

Prerequisites

  • Linux, FreeBSD or Windows host or container
  • Logs or traffic to analyze

Who it is for

  • Server administrators and self-hosters
  • Security teams managing many hosts

Alternatives & comparison

Fail2Ban is a single-host log watcher with firewall actions and no external dependencies; CrowdSec adds a shared reputation network, richer scenarios and enforcement at proxies and CDNs.

  • Fail2Ban

    Log-scanning intrusion-prevention daemon that temporarily bans IP addresses showing repeated authentication failures by updating firewall rules

    Open sourceOpen source

Sources & verification

Primary sources consulted for this record. Claims are tied to the fields each source supports; the automated link checker re-verifies every URL on a schedule.

  • License
    CrowdSec LICENSE (MIT)

    https://github.com/crowdsecurity/crowdsec/blob/master/LICENSE

    Supports: license_spdx, source_model

    checked Nov 1, 2026
  • Official documentation
    CrowdSec Documentation

    https://docs.crowdsec.net/

    Supports: capabilities, integrations, operating_systems

    checked Nov 1, 2026
  • Official site
    CrowdSec

    https://www.crowdsec.net/

    Supports: name, summary, vendor

    checked Nov 1, 2026
  • Pricing page
    CrowdSec Pricing

    https://www.crowdsec.net/pricing

    Supports: pricing_model

    checked Nov 1, 2026
Confidence
High
Reviewed
Nov 1, 2026
Links
Verified · Nov 2, 2026

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