How can I deal with split horizon DNS on the road warrior side of a VPN?



  • I want to set up a VPN for the following scenario:

    • I have a MAIN site with LAN only services.

    • The MAIN site uses Host Overrides in the DNS Resolver to give hostnames to LAN only services.

    • I have a REMOTE user that I'd like to connect to the MAIN site as an OpenVPN road warrior.

    • The REMOTE user wants to access services using the same hostnames as the MAIN site.

    • The remote site has a significantly faster internet connection than the MAIN site.  IE: Redirect Gateway is not an option.

    • The remote site has services using split horizon DNS.

    • The only device I control at the REMOTE site is a laptop for the road warrior.

    • The road warrior at the REMOTE site connects using OpenVPN GUI.

    I have an OpenVPN (Remote Access SSL / TLS) server that:

    • Does NOT use Redirect Gateway.

    • Pushes the LAN as an IPv4 Local network.

    • Pushes the firewalls domain as a DNS Default Domain.

    • Pushes the LAN IP as a DNS Server.

    This does everything I'd like except it breaks the REMOTE site's split horizon DNS.  For example, without being connected to the VPN, www.example.com resolves to a local IP.  After connecting to the VPN www.example.com resolves to the external IP.

    Are there any tricks I can use so only DNS lookups within the DNS Default Domain end up using the MAIN site's DNS Resolver?  Is there a better config for what I'm trying to accomplish?