Thank you.

For everyone's info, a "self made" connection such as this one requires (1) passport control, (2) customs, (3) exit the customs area into the public area of the airport, (4) getting new boarding pass (if not done online) and (5) re-enter the security area in the B section of the terminal for a domestic flight. The entire process took 30 minutes, which, I understand, is faster than average for Athens.