As perguntas frequentes - Como executar um servidor OpenVPN em um endereço IP dinâmico
While OpenVPN has no trouble handling the situation of a dynamic server, some extra configuration is required.
The first step is to get a dynamic DNS address which can be configured to "follow" the server every time the server's IP address changes. There are several dynamic DNS service providers available, such as dyndns.org.
The next step is to set up a mechanism so that every time the server's IP address changes, the dynamic DNS name will be quickly updated with the new IP address, allowing clients to find the server at its new IP address.
For that, use a NAT router appliance with dynamic DNS support, or a dynamic DNS client application such as ddclient to update the dynamic DNS address whenever the server IP address changes.
Há mais algumas conversas na página do Slashdot na VPN Soluções para instalações distribuídas , se você não se importar em analisá-las.