Database Administrator AuthenticationAs a DBA, you often perform special operations such as shutting down or starting up a database. Because only a DBA should perform these operations, the database administrator usernames require a secure authentication scheme.
This section contains the following topics:
Administrative PrivilegesSelecting an Authentication MethodUsing Operating System AuthenticationUsing Password File AuthenticationAdministrative PrivilegesAdministrative privileges that are required for an administrator to perform basic database operations are granted through two special system privileges, SYSDBA and SYSOPER. You must have one of these privileges granted to you, depending upon the level of authorization you require.
Note:The SYSDBA and SYSOPER system privileges allow access to a database instance even when the database is not open. Control of these privileges is totally outside of the database itself.
The SYSDBA and SYSOPER privileges can also be thought of as types of connections that enable you to perform certain database operations for which privileges cannot be granted in any other fashion. For example, you if you have the SYSDBA privilege, you can connect to the database by specifying CONNECT AS SYSDBA.
SYSDBA AND SYSOPERThe following operations are authorized by the
SYSDBA and
SYSOPER system privileges:
System Privilege
Operations Authorized
SYSDBA
Perform STARTUP and SHUTDOWN operations
ALTER DATABASE: open, mount, back up, or change character set CREATE DATABASE
DROP DATABASE
CREATE SPFILE
ALTER DATABASE ARCHIVELOG
ALTER DATABASE RECOVER
Includes the RESTRICTED SESSION privilege
Effectively, this system privilege allows a user to connect as user SYS.
SYSOPERPerform STARTUP and SHUTDOWN operations
CREATE SPFILE
ALTER DATABASE OPEN/MOUNT/BACKUP
ALTER DATABASE ARCHIVELOG
ALTER DATABASE RECOVER (Complete recovery only. Any form of incomplete recovery, such as UNTIL TIMECHANGECANCELCONTROLFILE requires connecting as SYSDBA.)
Includes the RESTRICTED SESSION privilege.This privilege allows a user to perform basic operational tasks, but without the ability to look at user data.
The manner in which you are authorized to use these privileges depends upon the method of authentication that you use.
When you connect with SYSDBA or SYSOPER privileges, you connect with a default schema, not with the schema that is generally associated with your username. For SYSDBA this schema is SYS; for SYSOPER the schema is PUBLIC.
Connecting with Administrative Privileges: Example
This example illustrates that a user is assigned another schema (SYS) when connecting with the SYSDBA system privilege. Assume that the sample user oe has been granted the SYSDBA system privilege and has issued the following statements:CONNECT oe/oe
CREATE TABLE admin_test(name VARCHAR2(20));
Later, user oe issues these statements:CONNECT oe/oe AS SYSDBA
SELECT * FROM admin_test;
User oe now receives the following error:ORA-00942: table or view does not exist
Having connected as SYSDBA, user oe now references the SYS schema, but the table was created in the oe schema.
See Also:
"Using Operating System Authentication" "Using Password File Authentication"Selecting an Authentication MethodThe following methods are available for
authenticating database administrators:
.Operating system (OS) authentication
.A password file
Notes:
These methods replace the
CONNECT INTERNAL syntax provided with earlier versions of Oracle Database. CONNECT INTERNAL is no longer supported.
Operating system authentication takes precedence over password file authentication. If you meet the requirements for operating system authentication, then even if you use a password file, you will be authenticated by operating system authentication.
Your choice will be influenced by whether you intend to administer your database locally on the same machine where the database resides, or whether you intend to administer many different databases from a single remote client.
Figure 1-2 illustrates the choices you have for database administrator authentication schemes.
Figure 1-2 Database Administrator Authentication Methods
Description of "Figure 1-2 Database Administrator Authentication Methods"If you are performing remote database administration, consult your Oracle Net documentation to determine whether you are using a secure connection. Most popular connection protocols, such as TCP/IP and DECnet, are not secure.
See Also:
Oracle Database Net Services Administrator's GuideNonsecure Remote ConnectionsTo connect to Oracle Database as a privileged user over a nonsecure connection, you must be authenticated by a password file.
When using password file authentication, the database uses a password file to keep track of database usernames that have been granted the SYSDBA or SYSOPER system privilege.
This form of authentication is discussed in
"Using Password File Authentication".
Local Connections and Secure Remote ConnectionsYou can connect to Oracle Database as a privileged user over a local connection or a secure remote connection in two ways:
1.If the database has a password file and you have been granted the SYSDBA or SYSOPER system privilege, then you can connect and be authenticated by a password file.
2.If the server is not using a password file, or if you have not been granted SYSDBA or SYSOPER privileges and are therefore not in the password file, you can use operating system authentication. On most operating systems, authentication for database administrators involves placing the operating system username of the database administrator in a special group, generically referred to as OSDBA. Users in that group are granted SYSDBA privileges. A similar group, OSOPER, is used to grant SYSOPER privileges to users.
Using Operating System AuthenticationThis section describes how to authenticate an administrator using the operating system.
OSDBA AND OSOPERTwo special operating system groups control database administrator connections when using operating system authentication. These groups are generically referred to as OSDBA and OSOPER. The groups are created and assigned specific names as part of the database installation process. The specific names vary depending upon your operating system and are listed in the following table:
Operating System Group UNIX user Group Windows User Group
OSDBA DBA ORA_DBA
OSOPER OPER ORA_OPER
The default names assumed by the Oracle Universal Installer can be overridden. How you create the OSDBA and OSOPER groups is operating system specific.
Membership in the OSDBA or OSOPER group affects your connection to the database in the following ways:
1.If you are a member of the OSDBA group and you specify AS SYSDBA when you connect to the database, then you connect to the database with the SYSDBA system privilege.
2.If you are a member of the OSOPER group and you specify AS SYSOPER when you connect to the database, then you connect to the database with the SYSOPER system privilege.
3.If you are not a member of either of these operating system groups and you attempt to connect as SYSDBA or SYSOPER, the CONNECT command fails.
See Also:
Your operating system specific Oracle documentation for information about creating the OSDBA and OSOPER groups
Preparing to Use Operating System AuthenticationTo enable operating system authentication of an administrative user:
1.Create an operating system account for the user.
2.Add the account to the OSDBA or OSOPER operating system defined groups.
Connecting Using Operating System AuthenticationA user can be authenticated, enabled as an administrative user, and connected to a local database by typing one of the following SQL*Plus commands:
CONNECT / AS SYSDBA
CONNECT / AS SYSOPER
For a remote database connection over a secure connection, the user must also specify the net service name of the remote database:
CONNECT /@net_service_name AS SYSDBA
CONNECT /@net_service_name AS SYSOPER
See Also:
*Plus User's Guide and Reference for syntax of the CONNECT command
Using Password File AuthenticationThis section describes how to authenticate an administrative user using password file authentication.
Preparing to Use Password File AuthenticationTo enable authentication of an administrative user using password file authentication you must do the following:
1.If not already created, create the password file using the ORAPWD utility:
ORAPWD FILE=filename PASSWORD=password ENTRIES=max_users
2.Set the REMOTE_LOGIN_PASSWORDFILE initialization parameter to EXCLUSIVE.(This is the default).
Note:
REMOTE_LOGIN_PASSWORDFILE is a static initialization parameter and therefore cannot be changed without restarting the database.
3.Connect to the database as user SYS (or as another user with the administrative privileges).
4.If the user does not already exist in the database, create the user.
5.Grant the SYSDBA or SYSOPER system privilege to the user:
GRANT SYSDBA to oe;
This statement adds the user to the password file, thereby enabling connection AS SYSDBA.
See Also:
"Creating and Maintaining a Password File" for instructions for creating and maintaining a password file.
Connecting Using Password File AuthenticationAdministrative users can be connected and authenticated to a local or remote database by using the SQL*Plus CONNECT command. They must connect using their username and password and the AS SYSDBA or AS SYSOPER clause. For example, user oe has been granted the SYSDBA privilege, so oe can connect as follows:
CONNECT oe/oe AS SYSDBA
However, user oe has not been granted the SYSOPER privilege, so the following command will fail:
CONNECT oe/oe AS SYSOPER
Note:
Operating system authentication takes precedence over password file authentication. Specifically, if you are a member of the OSDBA or OSOPER group for the operating system, and you connect as SYSDBA or SYSOPER, you will be connected with associated administrative privileges regardless of the username/password that you specify.
If you are not in the OSDBA or OSOPER groups, and you are not in the password file, then attempting to connect as SYSDBA or as SYSOPER fails.
See Also:
SQL*Plus User's Guide and Reference for syntax of the CONNECT command
