We have an internal C#/SQL app which pulls data about our instance on a daily basis, facilitating the management of all of our sites.

We are would like to monitor the flag indicating 'Restrict site to internal users' so we can identify status changes over time.

Looking at the API call sites?filterby=all call, I could not spot the setting here which is where I would have expected it.

Do you know if there is an API call which could yield this "Restrict site to internal users" setting for each site id?

Thanks