I've been trying to configure my macbook (10.9) with ice floor and openvpn to prevent outbound connections from my real IP. So i had to allow connection between my real IP and OpenDNS so as to be able to connect to my VPN. All works fine but when I disconnect wi-fi or when the computer restart/wake it can't connect to the VPN because the system sends queries to the DHCP assigned DNS (in my case shaw) which are blocked by my firewall. It works again when disable/enable wi-fi interface as DNS queries are sent to OpenDNS. I really don't understand.
So, How can I force the system to use the manual DNS and never use the one from DHCP ?
EDIT : Some more Informations
When OpenVPN can't connect (queries to those server are blocked by firewall) :
localhost:~ Charlie$ scutil --dns DNS configuration
resolver #1 nameserver : 184.108.40.206 nameserver : 220.127.116.11 if_index : 4 (en0) flags : Request A records reach : Reachable
But networks settings show OpenDNS not those one.
And when everything works the command above return OpenDNS servers.