Database Links

I have problems with the apparent lack of security for database links in Oracle7. When creating the link, there are 2 options for specifying the username on the remote database:

1. Hard-coded username/password. Useful for a permanent connection, but provides very little security. In addition, audit trails on the remote database show the hard-coded username, rendering them useless.
2. Dynamic (no) username/password. The link uses the username/password of the person actually using the link. Good for auditing, better security, BUT the username AND password must match exactly between the 2 databases. This means if the user changes their password on the local system, the link no longer works. (I verified this myself).

In addition, the use of a public DB link automatically allows everyone access to the link; a security disaster if you use a hard-coded password. Unlike other DB objects, you don't seem to be able to grant/revoke access to a DB link to specific users or roles. Creating and maintaining private DB links for all users (500+) would be a mess.

OK, the big questions:

1. Is there a way to control access to a public link from the local database?
2. If using the dynamic username/password is supposed to be so good, how can I keep the passwords in synch? This seems to defeat the "seamless" fascade that Oracle claims distributed apps can have if the user has to change them both (he shouldn't even know there IS a remote database).

Any information would be greatly appreciated. Please post your reply or email directly to the address below. Thanks in advance.

Rich Tefft                              Tracor Applied Sciences, Inc.
Database Administrator                  Rich_Tefft_at_ESD.Tracor.Com