Exit Point(s) During Oracle Login?

We're using a locally-developed authentication server for a userid/password repository. We have several systems using it already, but the next big push will be to add our Oracle servers to it, so that the userid/password will be the same as for other systems.

I've heard rumors that there's an "exit" (sorry, I'm an old mainframer) during Oracle login that allows you to replace Oracle's userid/password check with your own. Is there really such a thing, has anyone implemented it, and where's it documented? We have an incident open with Oracle, but it couldn't hurt to ask around. Thanks in advance ...

• Jim Blalock Clemson University