I'm using OpenVPN through Tunnelblick on MacOS X Lion.
I need to set specific DNS (with local IP, which works only when VPN is up) for the duration of this VPN session only.
I do not have access to the OpenVPN server configuration. Only client config. Also, DNS from the server doesn't work.
So it works like this: I connect to VPN, go the Network preferences and manually set DNS. After VPN is disconnected, I switch back to default. It works, but it needs to be automatic.
After some exploration I found that OpenVPN up- and down- scripts might help me with that. Unfortunately, I haven't found any specific documentation about how exactly it can be done.
How it can or can't be done? Any advice would be appreciated!