Fail2Ban

The fail2ban integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] allows for IPs banned by fail2ban to be displayed in the Home Assistant frontend.

Configuration

To enable this sensor, add the following lines to your configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file. After changing the configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file, restart Home Assistant to apply the changes. The integration is now shown on the integrations page under Settings > Devices & services. Its entities are listed on the integration card itself and on the Entities tab.

# Example configuration.yaml entry
sensor:
  - platform: fail2ban
    jails:
      - ssh
      - hass-iptables

Fail2Ban with Docker

For those of us using Docker, the above tutorial may not be sufficient. The following steps specifically outline how to set up fail2ban and Home Assistant when running Home Assistant within a Docker behind NGINX. The setup this was tested on was an unRAID server using the SWAG from linuxserver.io.

Set HTTP logger

In your configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file, add the following to the logger integration to ensure that Home Assistant prints failed login attempts to the log.

logger:
  logs:
    homeassistant.components.http.ban: warning

Edit the jail.local file

Next, we need to edit the jail.local file that is included with the Let’s Encrypt Docker linked above. Note, for this tutorial, we’ll only be implementing the [hass-iptables] jail.

Edit /mnt/user/appdata/letsencrypt/fail2ban/jail.local and append the following to the end of the file:

[hass-iptables]
enabled = true
filter = hass
action = iptables-allports[name=HASS]
logpath = /hass/home-assistant.log
maxretry = 5

Create a filter for the Home Assistant jail

Now we need to create a filter for fail2ban so that it can properly parse the log. This is done with a failregex. Create a file called hass.local within the filter.d directory in /mnt/user/appdata/letsencrypt/fail2ban and add the following:

[INCLUDES]
before = common.conf

[Definition]
failregex = ^%(__prefix_line)s.*Login attempt or request with invalid authentication from <HOST>.*$

ignoreregex =

[Init]
datepattern = ^%%Y-%%m-%%d %%H:%%M:%%S

Map log file directories

First, we need to make sure that fail2ban log can be passed to Home Assistant and that the Home Assistant log can be passed to fail2ban. When starting the Let’s Encrypt Docker, you need to add the following argument (adjust paths based on your setup):

/mnt/user/appdata/home-assistant:/hass

This will map the Home Assistant configuration directory to the Let’s Encrypt Docker, allowing fail2ban to parse the log for failed login attempts.

Now do the same for the Home Assistant Docker, but this time we’ll be mapping the fail2ban log directory to Home Assistant so that the fail2ban sensor is able to read that log:

/mnt/user/appdata/letsencrypt/log/fail2ban:/fail2ban

Send client IP to Home Assistant

By default, the IP address that Home Assistant sees will be that of the container (something like 172.17.0.16). What this means is that for any failed login attempt, assuming you have correctly configured fail2ban, the Docker IP will be logged as banned, but the originating IP is still allowed to make attempts. We need fail2ban to recognize the originating IP to properly ban it.

First, we have to add the following to the NGINX configuration file located in /mnt/user/appdata/letsencrypt/nginx/site-confs/default.

proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

This snippet should be added within your Home Assistant configuration, so you have something like the following:

server {
    ...
    location / {
        proxy_pass http://192.168.0.100:8123;
        proxy_set_header Host $host;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

    location /api/websocket {
        proxy_pass http://192.168.0.100:8123/api/websocket;
        proxy_set_header Host $host;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
    ...
}

Once that’s added to the NGINX configuration, we need to modify the Home Assistant configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] such that the X-Forwarded-For header can be parsed. This is done by adding the following to the http integration:

http:
  use_x_forwarded_for: true

At this point, once the Let’s Encrypt and Home Assistant dockers are restarted, Home Assistant should be correctly logging the originating IP of any failed login attempt. Once that’s done and verified, we can move onto the final step.

Add the fail2ban sensor

Now that we’ve correctly set everything up for Docker, we can add our sensors to configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] with the following:

sensor:
  - platform: fail2ban
    jails:
      - hass-iptables
    file_path: /fail2ban/fail2ban.log

Assuming you’ve followed all of the steps, you should have one fail2ban sensor, sensor.fail2ban_hassiptables, within your front-end.

Other debug tips

If, after following these steps, you’re unable to get the fail2ban sensor working, here are some other steps you can take that may help:

• Add logencoding = utf-8 to the [hass-iptables] entry
• Ensure the failregex you added to filter.d/hass.local matches the output within home-assistant.log
• Try changing the datepattern in filter.d/hass/local by adding the following entry (change the datepattern to fit your needs). source

  [Init]
  datepattern = ^%%Y-%%m-%%d %%H:%%M:%%S