Windows 8+ - ensuring DNS lookups are secure

Starting with Windows 8.1, Microsoft introduced a new feature for resolving hostnames to IP addresses. Whenever an application wants to resolve a hostname, a DNS query is sent out over all network adapters found in the system. The answer from the first adapter that responds to the query is used.

If a user wants to tunnel all traffic over a VPN in a secure manner, then this feature is not desirable. In a hostile network environment, a bogus IP address could be returned or even the fact that a DNS lookup for a particular host is made could be considered dangerous.

Starting with OpenVPN 2.3.10, a new option, block-outside-dns, was added to suppress this feature. In this recipe, we will show how to use this option.

Getting ready

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 2.3.11. The client computer was...