What is ansible-fail2ban? 
It is an ansible role to install and configure fail2ban.
What problem does it solve and why is it useful?
Security is important and fail2ban is an excellent tool to harden your server with minimal or even no configuration.
Role variables
Below is a list of default values along with a description of what they do.
# Which log level should it be output as?
# 1 = ERROR, 2 = WARN, 3 = INFO, 4 = DEBUG
fail2ban_loglevel: 3
# Where should log outputs be sent to?
# SYSLOG, STDERR, STDOUT, file
fail2ban_logtarget: /var/log/fail2ban.log
# Where should the socket be created?
fail2ban_socket: /var/run/fail2ban/fail2ban.sock
# Which IP address, CIDR mark or DNS host should be ignored?
fail2ban_ignoreip: 127.0.0.1/8
# How long in seconds should the ban last for?
fail2ban_bantime: 600
# How many times can they try before getting banned?
fail2ban_maxretry: 6
# How should the file changes be detected?
# gamin, polling, auto
fail2ban_backend: polling
# Where should e-mail reports be sent to?
fail2ban_destemail: root@localhost
# How should the ban be applied?
# iptables, iptables-new, iptables-multiport, shorewall, etc.
fail2ban_banaction: iptables-multiport
# What e-mail action should be used?
# sendmail or mail
fail2ban_mta: sendmail
# What should the default protocol be?
fail2ban_protocol: tcp
# Which chain would the JUMPs be added into iptables-*?
fail2ban_chain: INPUT
# What should the default ban action be?
# action_, action_mw, action_mwl
fail2ban_action: action_
# What services should fail2ban monitor?
# You can define fail2ban_services as an empty string to not monitor anything.
# You can define multiple services as a standard yaml list.
fail2ban_services:
# The name of the service
# REQUIRED.
- name: ssh
# Is it enabled?
# OPTIONAL: Defaults to "true" (must be a string).
enabled: "true"
# What port does the service use?
# Separate multiple ports with a comma, no spaces.
# REQUIRED.
port: ssh
# What protocol does the service use?
# OPTIONAL: Defaults to the protocol listed above.
protocol: tcp
# What filter should it use?
# REQUIRED.
filter: sshd
# Which log path should it monitor?
# REQUIRED.
logpath: /var/log/auth.log
# How many times can they try before getting banned?
# OPTIONAL: Defaults to the maxretry listed above.
maxretry: 6
# What should the default ban action be?
# OPTIONAL: Defaults to the action listed above.
action: action_
# How should the ban be applied?
# OPTIONAL: Defaults to the banaction listed above.
banaction: iptables-multiport
# The amount in seconds to cache apt-update.
apt_cache_valid_time: 86400
Example playbook
For the sake of this example let's assume you have a group called app and you have a typical site.yml file.
To use this role edit your site.yml file to look something like this:
---
- name: ensure app servers are configured
- hosts: app
roles:
- { role: nickjj.fail2ban, sudo: true, tags: fail2ban }
Let's say you want to edit a few values, you can do this by opening or creating group_vars/app.yml which is located relative to your inventory directory and then making it look something like this:
---
fail2ban_services:
- name: ssh
port: ssh
filter: sshd
logpath: /var/log/auth.log
- name: postfix
port: smtp,ssmtp
filter: postfix
logpath: /var/log/mail.log
Installation
$ ansible-galaxy install nickjj.fail2ban
Requirements
Tested on ubuntu 12.04 LTS but it should work on other versions that are similar.
Ansible galaxy
You can find it on the official ansible galaxy if you want to rate it.
License
MIT