PSD2 client cert check and passthrough Subject DN

> I have been asked to implement a client cert check with external CA's and if the check passes then pass through the client cert Subject DN to the backend application for checking and action by application.

You need to use the Client Certificate Constrained Delegation (C3D) feature:

K72668381:  Overview of the SSL Client Certificate Constrained Delegation feature

K14065425:  Configuring Client Certificate Constrained Delegation (C3D)