Is there some software that can be configured to recognize certain WLAN SSIDs as tethering connection and block all traffic from programs other than those explicitly added to a whitelist?
I know that it should in theory be possible using just the Windows firewall; If I'd find that a satisfactory solution, I would consider my question a clear duplicate.
Considering though how quickly a 1GB/mth volume can be exceeded when Steam starts downloading some update, I'd rather prefer a special-purpose program that makes the task easy and misconfiguration unlikely. Ideally there should be a taskbar icon indicating that the limitation rule has been enacted, similiar to Nvidia optimus indicating dedicated graphics activity.