One of the most powerful features of OpenVPN is its scripting capability and the ability to extend OpenVPN itself through the use of plugins. Using client-side scripting, the connection process can be tailored to the site-specific needs, such as setting up advanced routing options, adding firewall rules or mapping network drives. With server-side scripting, it is possible to assign a custom IP address to different clients, or to extend the authentication process by adding an extra username and password check. Plugins are very useful when integrating OpenVPN authentication into existing authentication frameworks, such as PAM, LDAP, or even Active Directory.

In this chapter, the focus will be on scripting, both at the client side and at the server side, and on a few often-used plugins.