Is there a way to force OS X Lion to connect to a VPN whenever there's network connectivity?

Question

I need to deploy a couple of remote computers and I need them to always connect to the VPN whenever there is internet connectivity. Is this possible? If so, how?

Answer 1

First, you need to set up locationchanger, a script that is launched whenever (possibly) the network settings have changed.

I've been using a heavily modified version (no location detection, just show a Growl notification whenever anything is changed, i.e. in the section "do some stuff here that needs to happen after every network change") for over a year, and it's quite reliable. Sometimes it detects two changes in quick succession, but that's it. Since your needs are more along the defaults, it will probably work even better for you.

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Open AppleScript Editor, and paste the following code:

tell application "System Events"
    tell current location of network preferences
        if exists service "Displayed Name" then
            set VPNservice to service "Displayed Name"
            if connected of first configuration of VPNservice then
                disconnect VPNservice
            else
                connect VPNservice
            end if
        else
            display alert "Could not find VPN connection"
        end if
    end tell
end tell

Replace Displayed Name by the name of your VPN connection in System Preferences » Network.

Save as application, e.g. /Applications/Utilities/Toggle VPN.app

Then, edit the locationchanger script and add

open "/Applications/Utilities/Toggle VPN.app"

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If you don't want an icon to bounce in the Dock whenever you change something, you san save the AppleScript as script instead, and execute it from locationchanger like this:

osascript "/path/to/Toggle VPN.scpt"

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This solution will require some experimentation on your part. The reason is obvious: Connecting or disconnecting a VPN is a change in the network configuration. So given what I wrote here, it's possible that you connect to a network, the script connects to the VPN, the VPN configuration change triggers the script again, and it disconnects.

Of course, you can simply remove the line that says disconnect VPNservice and try to. It really depends on the exact behavior you want. But these are the building blocks.