OpenVPN is an open source SSL VPN, which works in many Linux distributions.
Your VPN server will be accessable from several operating systems and smartphones.
There 2 ways to get to an openVPN server, but here i will show you the easier way.
This is tutorial shows how to add a Fail2ban custom filter rule for web applications e.g. joomla admin page, moodle, wordpress.
Fail2ban is needed to block brute-force attacks. Easiest explanation: this attack is performed when page is entered through trying passwords again and again till the right password was found. This will be avoided for your web application by this fail2ban custom filter rule.