"OpenVPN, or Open Virtual Private Network, is a tool for
creating networking "tunnels" between and among groups of computers
that are not on the same local network. This is useful if you have
services on a local network and need to access them remotely but
don't want these services to be publicly accessible. By integrating
with OpenSSL, OpenVPN can encrypt all VPN traffic to provide a
secure connection between machines.
"The OpenLDAP backend of iRedmail allows you to integrate all
kinds of applications and to realize centralized account
management. This tutorial shows you how to integrate OpenVPN into
the iredmail ldap backend on Debian 6.0; passwords will be stored
in ldap and you can change passwords through webmail."