Using an auth-user-pass-verify script
Other than certificates and private keys, OpenVPN also offers the option to use a username and password mechanism for verifying client access. In this recipe, we will demonstrate how to set up an auth-user-pass-verify script, which is executed on the server side when a client connects. This script can be used to look up a user in a database or file and can also be used to verify that the right password was specified.
Getting ready
Install OpenVPN 2.3 or higher on two computers. Make sure that the computers are connected over a network. Set up the client and server certificates using the first recipe from Chapter 2, Client-server IP-only Networks. For this recipe, the server computer was running CentOS 6 Linux and OpenVPN 2.3.10, and the client was running Fedora 22 and OpenVPN 2.3.10. For the server, keep the server configuration file, basic-udp-server.conf, from the Server-side routing recipe, from Chapter 2, Client-server IP-only Networks.
