How to block DNS from DHCP on OS X 10.9?

-1

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 ?

Thanks

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[0] : 64.59.144.92 nameserver[1] : 64.59.150.138 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.

Lich4r

Posted 2014-09-27T02:59:34.247

Reputation: 155

Answers

-1

Seems like editing openvpn profile by adding

push "dhcp-option 208.67.222.222"

and same for the other DNS solved the problem here.

Lich4r

Posted 2014-09-27T02:59:34.247

Reputation: 155

If you are on the same network most of then just go to System Preferences > Network and change Wifi from DHCP to Manual.

This way you can enter right information just once, and only deal with problems when you visit "some" of the networks, since most routers will have same ip (192.168.1.1). Preferably set your Ip to 192.168.1.240, because it is rare that you will find computer with such high ip address.

sgp667

Posted 2014-09-27T02:59:34.247

Reputation: 563

I thought of that but it does't solve my problem because OpenVPN can't even go to the first step of connection (which is resolve DNS) and is totally blocked despite if I'm using a fix IP which is the same than the one DHCP provided to me. – Lich4r – 2014-09-27T22:33:58.807

Well you said that in your case problem is that your computer fails to use proper DNS server, this will let you choose right DNS server by default. – sgp667 – 2014-09-28T02:17:50.723

Point of manual settings is that you pick your own DNS server, rest of settings just have to be compliant with router on your network. – sgp667 – 2014-09-28T02:19:09.830

When I put on manual, openvpn can't even try to resolve DNS. It's totally blocked – Lich4r – 2014-09-28T05:06:48.917

Then I'm not sure if DNS is the problem. Maybe someone should take a look at the computer, because they can get fuller picture of the problem. – sgp667 – 2014-09-28T19:23:41.907

When it doesn't work (randomly it seems) I have to flush dns cache and enable/disable Wi-fi and then it works again.. Should I explain more the firewall rules I'm using ? – Lich4r – 2014-09-29T01:39:31.570