How to implement nodejs access restricted authorization system?

Question

OAuth

Good day. There was a task to make an authorization and authentication server, there is a certain application and it accesses the AUTH server when a user tries to log in and sends a response. The data validation mechanism is as clear as daylight to me, but here's how to restrict access to the server so that requests cannot be made from the left site. There was an idea to put a whitelist in cors, but how to give access to applications that do not have domains?
Thanks in advance

Answer 1

Most likely, screw OAUTH so that access is only for registered applications.