You don't need any external accounts or services. You can turn on a dyndns service or a proxy service optionally, for convenience. You might need an account for

You don't need any external accounts or services. You can turn on a dyndns service or a proxy service optionally, for convenience. You might need an account for those. You can and should wall the thing off. What happens is, your photos only back up when you are at your house, or when you connect your phone to your VPN.