Not sure this is the good place to provide this information, but it is the only idea that comes to me for the moment being.
With my mobile connection, Orange provides me a new IP each day. As a results, each time I want to connect to the TeamViewer forums, I have to authenticate my browser, whereas maybe another Orange customer who has the IP I had last time would not have to do so. Well I am joking he does not have the same machine id. But if we rely on the machine id, is that control procedure useful ?