Oracle Database Discussions

Hello,

I've experimented a little bit with different authentication methods, had a working setup and now I've problems to reproduce this setup.

I'd like to let users login using their domain account. So I created users using

SQL> create user "OPS$DOMAIN\USER" identified externally;
SQL> grant connect to "OPS$DOMAIN\USER";

But I fail to connect from a client logged in with the domain account. Further investigations show that the user connects to oracle as OPS$USER and not OPS$DOMAIN\USER.
That's bad for me because with that setting local users with the same name can connect to the database too. Previously in my setup it was working that only domain users and not local users could login - but what configuration is missing to distinguish between local and domain users? What else parameters are important to check for oracle to use "OPS$DOMAIN\USER"?

The parameter os_authent_prefix is set to "ops$" and remote_os_authent is set to true.
I know that remote_os_authent=true is not advised but we need to connect our domain users and we don't have the oracle advanced security option for using kerberos or oracle enterprise for using ldap.