SYS AS SYSDBA Should Require Password? Oracle Authentication Explained (Complete Guide) 📅 Last Updated: August 2026 This guide has been completely updated for Oracle Database 11g, 12c, 18c, 19c, 21c, and Oracle Database 23ai. It explains how SYSDBA authentication works, the difference between operating system authentication and password file authentication, why sqlplus / as sysdba does not require a password, how remote SYSDBA authentication works, and Oracle security best practices for production environments. One of the most common questions asked by Oracle Database Administrators is: "Why can I connect using sqlplus / as sysdba without entering the SYS password?" Many administrators assume that SYSDBA authentication should always require a password. However, Oracle Database supports multiple authentication mechanisms, and the answer depends on how the connection is being established. When connecting locally on the database server, Oracle ...