Oracle Database B10772-01 Administrator's Manual page 308

About Using Current User Database Links for Enterprise User Security
SSL to authenticate to the other databases. To specify a database as untrusted that is
part of a trusted enterprise domain, use the PL/SQL package DBMS_
DISTRIBUTED_TRUST_ADMIN. To obtain a list of trusted servers, use the
TRUSTED_SERVERS view.
11-24 Oracle Database Advanced Security Administrator's Guide
Oracle Advanced Security does not support RADIUS
Note:
authentication over database links.
See Also:
"What is Meant by Trusted Databases"
Oracle Database Heterogeneous Connectivity Administrator's Guide,
for additional information about current user database links
Oracle Database SQL Reference, for more information about SQL
syntax
PL/SQL Packages and Types Reference, for information about the
PL/SQL package DBMS_DISTRIBUTED_TRUST_ADMIN
Oracle Database Reference, for information about the TRUSTED_
SERVERS view
Chapter 7, "Configuring Secure Sockets Layer Authentication"
Chapter 8, "Using Oracle Wallet Manager"
about creating wallets
on page 11-26
for information