Sometimes After a sync with production our testing site needs to be re-secured (since it's testing we don't want people using it)
install the securesite module
obviously you don't need to do this every time if you also install the module on your production enviroment, but switch it off overthere.
Activate the module on http://yourURL/admin/build/modules
Change the Settings: http://yourURL/admin/settings/securesite (Force authenticatoin ‘Always’)
That should do it
Props to my good friend Sven