I need to design an application for internal corporate use. The application must be hosted externally. Ideally I'd like that application to be able to authenticate and authorize against the corporate ActiveDirectory.
However 2 problems here:
- Authentication must work even if corporate network is unavailable.
- I'd prefer to not replicate ActiveDirectory to an external location for security reasons. BTW is it right concern?
I have a few stupid ideas like having externally hosted "LDAP proxy" which would save credential hashes for limited time. That time should be enough to bring network up. While the network is down "LDAP proxy" checks credentials against local hashes. This idea seems to be too home-made and insecure. Is it possible to implement with ActiveDirectory Lightweight Directory Services (AD LDS)?
If the ideal above isn't feasible is there any 3rd party authentication solution? With account management, password policies, API, etc.