This is a community guide and is not officially supported. If you have any issues, please reach out to the author.
CrowdSec is a modern, open-source, collaborative behavior detection engine, integrated with a global IP reputation network. It functions as a massively multiplayer firewall, analyzing visitor behavior and responding appropriately to various types of attacks.

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Installation

Crowdsec can be installed using the Pangolin Installer.

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Configuration

By default, Crowdsec is installed with a basic configuration, which includes the Crowdsec Bouncer Traefik plugin.

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Choose the right logs

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Syslog

For systems utilizing Syslog, the following volumes should be added to the docker-compose.yml file: 
service:
  crowdsec:
    volumes:
      - /var/log/auth.log:/var/log/auth.log:ro
      - /var/log/syslog:/var/log/syslog:ro
Create a syslog.yaml file under /config/crowdsec/acquis.d with the following content: 
filenames:
  - /var/log/auth.log
  - /var/log/syslog
labels:
  type: syslog

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Journalctl

To log iptables to journalctl, execute the following command on your host system: 
iptables -A INPUT -j LOG --log-prefix "iptables: "
Update the docker-compose.yml file as follows: 
service:
  crowdsec:
    image: crowdsecurity/crowdsec:latest-debian
    environment:
      COLLECTIONS: crowdsecurity/traefik crowdsecurity/appsec-virtual-patching crowdsecurity/appsec-generic-rules crowdsecurity/linux crowdsecurity/iptables
    volumes:
      - ./config/crowdsec:/etc/crowdsec
      - ./config/crowdsec/db:/var/lib/crowdsec/data
      - ./config/traefik/logs:/var/log/traefik:ro
      - /var/log/journal:/var/log/host:ro
Create a journalctl.yaml file under /config/crowdsec/acquis.d with the following content: 
source: journalctl
journalctl_filter:
  - "--directory=/var/log/host/"
labels:
  type: syslog

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Securing the Host System (SSH)

By default, only Traefik requests are secured through the Crowdsec bouncer. To extend protection to your host system (e.g., SSH), follow these steps to add a firewall bouncer:
  1. Install the Crowdsec repositories. Refer to the installation documentation:
curl -s https://install.crowdsec.net | sudo sh
  1. Install the firewall bouncer. For Debian/Ubuntu systems using IPTables, refer to the documentation:
sudo apt install crowdsec-firewall-bouncer-iptables
  1. Create an API key for the firewall bouncer to communicate with your CrowdSec Docker container. (“vps-firewall” is a placeholder name for the key):
docker exec -it crowdsec cscli bouncers add vps-firewall
  1. Copy the dispalyed API key and insert it into the bouncer’s configuration file:
nano /etc/crowdsec/bouncers/crowdsec-firewall-bouncer.yaml
  1. Restart the firewall bouncer:
systemctl restart crowdsec-firewall-bouncer
  1. Update the docker-compose.yml file to expose communication port 8080 for the CrowdSec container and restart the container:
service:
  crowdsec:
    ports:
      - 6060:6060 # Metrics port
      - 8080:8080 # Local API port
Docker’s NAT-based port publishing feature automatically exposes all ports: defined in the docker-compose file on all network interfaces. This behavior can bypass your host firewall settings, potentially exposing services that you did not intend to make public. Please see complete warning about exposing ports.
  1. Verify communication between the firewall bouncer and the CrowdSec container by running:
docker exec crowdsec cscli metrics
The output should look like this: 
+------------------------------------------------------------------+
| Local API Bouncers Metrics                                       |
+---------------------------+----------------------+--------+------+
| Bouncer                   | Route                | Method | Hits |
+---------------------------+----------------------+--------+------+
| traefik-bouncer           | /v1/decisions/stream | HEAD   | 2    |
| traefik-bouncer@10.0.4.20 | /v1/decisions        | GET    | 3    |
| vps-firewall              | /v1/decisions/stream | GET    | 84   | <---------
+---------------------------+----------------------+--------+------+

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Custom Ban Page

To display a custom ban page to attackers, follow these steps:
  1. Place a ban.html page in the /config/traefik directory. If you prefer not to create your own, you can download the official example:
wget https://raw.githubusercontent.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/refs/heads/main/ban.html
  1. Update the /config/traefik/dynamic_config.yml file to include the following:
http:
  middlewares:
    crowdsec:
      plugin:
        crowdsec:
          banHTMLFilePath: /etc/traefik/ban.html

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Custom Captcha Page

To use a custom captcha page, follow these steps:
  1. Place a captcha.html page in the /config/traefik directory. If you don’t want to create your own, you can download the official example:
wget https://raw.githubusercontent.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/refs/heads/main/captcha.html
  1. Update the /config/traefik/dynamic_config.yml file with the following configuration, replacing <SERVICE> with your captcha provider (MUST BE either hcaptcha, recaptcha, or turnstile), and <KEY> with the appropriate site and secret keys:
http:
  middlewares:
    crowdsec:
      plugin:
        crowdsec:
          captchaHTMLFilePath: /etc/traefik/captcha.html
          captchaGracePeriodSeconds: 300
          captchaProvider: <SERVICE>
          captchaSiteKey: <KEY>
          captchaSecretKey: <KEY>

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Testing

You can test your configuration by adding a temporary ban or captcha for your IP. The ban will last for one minute. To add a ban: 
docker exec crowdsec cscli decisions add --ip <YOUR IP> -d 1m --type ban
To trigger a captcha challenge: 
docker exec crowdsec cscli decisions add --ip <YOUR IP> -d 1m --type captcha