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fail2ban Cookbook

Installs and configures fail2ban, a utility that watches logs for failed login attempts and blocks repeat offenders with firewall rules. On Redhat systems this cookbook will enable the EPEL repository in order to retrieve the fail2ban package.

Maintainers

This cookbook is maintained by the Sous Chefs. The Sous Chefs are a community of Chef cookbook maintainers working together to maintain important cookbooks. If you’d like to know more please visit sous-chefs.org or come chat with us on the Chef Community Slack in #sous-chefs.

Requirements

Platforms

• Debian/Ubuntu
• RHEL/CentOS/Scientific/Amazon/Oracle
• Fedora
• OpenSUSE

Chef

• Chef 15.3+

Cookbooks

• yum-epel

Recipes

default

Installs the fail2ban package, manages 2 templates: /etc/fail2ban/fail2ban.conf and /etc/fail2ban/jail.conf, and manages the fail2ban service.

Attributes

This cookbook has a set of configuration options for fail2ban

• default['fail2ban']['loglevel'] = 'INFO'
• default['fail2ban']['logtarget'] = '/var/log/fail2ban.log'
• default['fail2ban']['syslogsocket'] = 'auto'
• default['fail2ban']['socket'] = '/var/run/fail2ban/fail2ban.sock'
• default['fail2ban']['pidfile'] = '/var/run/fail2ban/fail2ban.pid'
• default['fail2ban']['dbfile'] = '/var/lib/fail2ban/fail2ban.sqlite3'
• default['fail2ban']['dbpurgeage'] = 86_400

This cookbook has a set of configuration options for jail.conf

• default['fail2ban']['ignoreip'] = '127.0.0.1/8'
• default['fail2ban']['findtime'] = 600
• default['fail2ban']['bantime'] = 300
• default['fail2ban']['maxretry'] = 5
• default['fail2ban']['backend'] = 'polling'
• default['fail2ban']['email'] = 'root@localhost'
• default['fail2ban']['sendername'] = 'Fail2Ban'
• default['fail2ban']['action'] = 'action_'
• default['fail2ban']['banaction'] = 'iptables-multiport'
• default['fail2ban']['mta'] = 'sendmail'
• default['fail2ban']['protocol'] = 'tcp'
• default['fail2ban']['chain'] = 'INPUT'

This cookbook makes use of a hash to compile the jail.local-file and filter config files:

default['fail2ban']['services'] = {
  'ssh' => {
        "enabled" => "true",
        "port" => "ssh",
        "filter" => "sshd",
        "logpath" => node['fail2ban']['auth_log'],
        "maxretry" => "6"
     },
  'smtp' => {
        "enabled" => "true",
        "port" => "smtp",
        "filter" => "smtp",
        "logpath" => node['fail2ban']['auth_log'],
        "maxretry" => "6"
     }
}

The following attributes can be used per service:

• backend
• banaction
• bantime
• enabled
• filter
• findtime
• ignorecommand
• logpath
• maxretry
• port
• protocol

Creating custom fail2ban filters:

default['fail2ban']['filters'] = {
  'nginx-proxy' => {
        "failregex" => ["^<HOST> -.*GET http.*"],
        "ignoreregex" => []
     },
}

In the case you would like to get Slack notifications on IP addresses banned/unbanned, this cookbook supports it by setting the following attributes:

# A Slack webhook looks like this:
# https://hooks.slack.com/services/A123BCD4E/FG5HI6KLM/7n8opqrsT9UVWxyZ0AbCdefG
default['fail2ban']['slack_webhook'] = nil
# Then setting the Slack channel name without the hashtag (#)
default['fail2ban']['slack_channel'] = 'general'

Then you will get notifications like this:

[hostname] Banned 🇳🇬 217.117.13.12 in the jail sshd after 5 attempts

Resources

fail2ban_filter

Manages fail2ban filters in /etc/fail2ban/filters.d/.

Actions

• create - Default. Creates a fail2ban filter.
• delete - Deletes a fail2ban filter.

Properties

• filter - Specifies the name of the filter. This is the name property.
• source - Specifies the template source. By default, this is set to filter.erb.
• cookbook - Specifies the template cookbook. By default, this is set to fail2ban.
• failregex - Specifies one or multiple regular expressions matching the failure.
• ignoreregex - Specifies one or multiple regular expressions to ignore.

Examples

Configure a file for webmin authentication with multiple regular expressions matching the failure.

fail2ban_filter 'webmin-auth' do
  failregex ["^%(__prefix_line)sNon-existent login as .+ from <HOST>\s*$",
             "^%(__prefix_line)sInvalid login as .+ from <HOST>\s*$"]
end

fail2ban_jail

Manages fail2ban jails in /etc/fail2ban/jail.d/.

Actions

• create - Default. Creates a fail2ban jail.
• delete - Deletes a fail2ban jail.

Properties

• jail - Specifies the jail name. This is the name property.
• source - Specifies the template source. By default, this is set to jail.erb.
• cookbook - Specifies the template cookbook. By default, this is set to fail2ban.
• filter - Specifies the name of the filter to be used by the jail to detect matches.
• logpath - Specifies the path to the log file which is provided to the filter.
• protocol - Specifies the protocol type, e.g. tcp, udp or all.
• ports - Specifies an array of port(s) to watch.
• maxretry - Specifies the number of matches which triggers ban action.
• ignoreips - Specifies an array of IP addresses to ignore.

Examples

Create a new fail2ban jail for SSH that uses existing filter sshd and which bans client after 3 tries.

fail2ban_jail 'ssh' do
  ports %w(ssh)
  filter 'sshd'
  logpath node['fail2ban']['auth_log']
  maxretry 3
end

Issues related to rsyslog

If you are using rsyslog parameter "$RepeatedMsgReduction on" in rsyslog.conf file then you can get "Last message repeated N times" in system log file (for example auth.log). Fail2ban will not work because the internal counter maxretry will not expand the repeated messages. Change parameter "$RepeatedMsgReduction off" in rsyslog.conf file for maximum accuracy of failed login attempts.

This rsyslog parameter is default ON for ubuntu 12.04 LTS for example.

Contributors

This project exists thanks to all the people who contribute.

Backers

Thank you to all our backers!

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