Scripted email messages for fail2ban actions via Mailgun

When fail2ban executes and action, we run these scripts to send the appropriate email with Mailgun

Install

Download the app and set up config files.

$ cd /usr/local/bin
$ git clone https://github.com/scimusmn/fail2ban-mailgun.git
$ cd fail2ban-mailgun
$ cp mailgun_api.default.conf /etc/mailgun_api.conf

Edit the api.conf file, adding your Mailgun API details.

Define a new action in fail2ban at: /etc/fail2ban/action.d/mailgun.conf

[Definition]
actionstart =
actionstop =
actioncheck =
actionban = /usr/local/bin/fail2ban-mailgun/mail.sh ban
actionun = /usr/local/bin/fail2ban-mailgun/mail.sh unban

Modify or add an action entry in the jail you wish to configure. We're assuming that you've copied jail.conf to jail.local and will be adding this rule to the SSH jail entry.

[ssh]

enabled  = true
port     = ssh
filter   = sshd
logpath  = /var/log/auth.log
maxretry = 6
action = %(action_)s
    mailgun

The last part states to set the action to the default action variable, likely defined above in your jail.local file, and then to add the mailgun action to the ban process.