com.googlecode.pymacadmin.crankd.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>NSWorkspace</key>
	<key>SystemConfiguration</key>
	<dict>
		<key>State:/Network/Global/IPv4</key>
		<dict>
			<key>command</key>
			<string>~/Dropbox/dev/scripts/vpn_connect_disconnect.bash</string>
		</dict>
	</dict>
</dict>
</plist>

vpn_connect_disconnect.bash

#!/bin/bash

# called by PyMacAdmin: crankd.
# ~/Library/Preferences/com.googlecode.pymacadmin.crankd.plist

function connect {
/usr/bin/env osascript <<EOF
tell application "System Events"
  tell current location of network preferences
		set vpnConn to the service "Sampa"
		if vpnConn is not null then
			if current configuration of vpnConn is not connected then
				connect vpnConn
			end if
		end if
	end tell
end tell
EOF
}

function disconnect {
/usr/bin/env osascript <<EOF
tell application "System Events"
  tell current location of network preferences
    set vpnConn to the service "Sampa"
    if vpnConn is not null then
      if current configuration of vpnConn is connected then
        disconnect vpnConn
      end if
    end if
  end tell
end tell
EOF
}

if [ $(/usr/sbin/networksetup -getinfo Wi-Fi | grep -c 'IP address:') == '2' ]
then
  echo 'connected'
  connect
else
  echo 'not connected'
  disconnect
fi