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November 25, 2009

Password file (orapwd utility) in Oracle

Oracle password file stores passwords for users with administrative privileges.

If the DBA wants to start up an Oracle instance there must be a way for Oracle to authenticate the DBA. Obviously, DBA password cannot be stored in the database, because Oracle cannot access the database before the instance is started up. Therefore, the authentication of the DBA must happen outside of the database. There are two distinct mechanisms to authenticate the DBA:
(i) Using the password file or
(ii) Through the operating system (groups). Any OS user under dba group, can login as SYSDBA.

The default location for the password file is:
$ORACLE_HOME/dbs/orapw$ORACLE_SID on Unix,
%ORACLE_HOME%\database\PWD%ORACLE_SID%.ora on Windows.

REMOTE_LOGIN_PASSWORDFILE
The init parameter REMOTE_LOGIN_PASSWORDFILE specifies if a password file is used to authenticate the Oracle DBA or not. If it set either to SHARED or EXCLUSIVE, password file will be used.

REMOTE_LOGIN_PASSWORDFILE is a static initialization parameter and therefore cannot be changed without bouncing the database.

Following are the valid values for REMOTE_LOGIN_PASSWORDFILE:

NONE - Oracle ignores the password file if it exists i.e. no privileged connections are allowed over non secure connections. If REMOTE_LOGIN_PASSWORDFILE is set to EXCLUSIVE or SHARED and the password file is missing, this is equivalent to setting REMOTE_LOGIN_PASSWORDFILE to NONE.

EXCLUSIVE (default) - Password file is exclusively used by only one (instance of the) database. Any user can be added to the password file. Only an EXCLUSIVE file can be modified. EXCLUSIVE password file enables you to add, modify, and delete users. It also enables you to change the SYS password with the ALTER USER command.

SHARED - The password file is shared among databases. A SHARED password file can be used by multiple databases running on the same server, or multiple instances of an Oracle Real Application Clusters (RAC) database. However, the only user that can be added/authenticated is SYS.


A SHARED password file cannot be modified i.e. you cannot add users to a SHARED password file. Any attempt to do so or to change the password of SYS or other users with the SYSDBA or SYSOPER or SYSASM (this is from Oracle 11g) privileges generates an error. All users needing SYSDBA or SYSOPER or SYSASM system privileges must be added to the password file when REMOTE_LOGIN_PASSWORDFILE is set to EXCLUSIVE. After all users are added, you can change REMOTE_LOGIN_PASSWORDFILE to SHARED.

This option is useful if you are administering multiple databases or a RAC database.

If a password file is SHARED or EXCLUSIVE is also stored in the password file. After its creation, the state is SHARED. The state can be changed by setting REMOTE_LOGIN_PASSWORDFILE and starting the database i.e. the database overwrites the state in the password file when it is started up.

ORAPWD
You can create a password file using orapwd utility. For some Operating systems, you can create this file as part of standard installation.

Users are added to the password file when they are granted the SYSDBA or SYSOPER or SYSASM privilege.

The Oracle orapwd utility assists the DBA while granting SYSDBA, SYSOPER and SYSASM privileges to other users. By default, SYS is the only user that has SYSDBA and SYSOPER privileges. Creating a password file, via orapwd, enables remote users to connect with administrative privileges.

$ orapwd file=password_file_name [password=the_password] [entries=n] [force=Y|N] [ignorecase=Y|N] [nosysdba=Y|N]

Examples:
$ orapwd file=orapwSID password=sys_password force=y nosysdba=y
$ orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID password=secret
$ orapwd file=orapwprod entries=32 force=y
C:\orapwd file=%ORACLE_HOME%\database\PWD%ORACLE_SID%.ora password=2012 entries=20
C:\orapwd file=D:\oracle11g\product\11.1.0\db_1\database\pwdsfs.ora password=id entries=8 force=y
$ orapwd file=orapwPRODB3 password=abc123 entries=12 ignorecase=n
$ orapwd file=orapwprodb password=oracle1 ignorecase=y

There are no spaces permitted around the equal-to (=).

The following describe the orapwd command line arguments.

FILE
Name to assign to the password file, which will hold the password information. You must supply complete path. If you supply only filename, the file is written to the current directory. The contents are encrypted and are unreadable. This argument is mandatory.

The filenames allowed for the password file are OS specific. Some operating systems require the password file to adhere to a specific format and be located in a specific directory. Other operating systems allow the use of environment variables to specify the name and location of the password file.

If you are running multiple instances of Oracle Database using Oracle Real Application Clusters (RAC), the environment variable for each instance should point to the same password file.

It is critically important to secure password file.

PASSWORD
This is the password the privileged users should enter while connecting as SYSDBA or SYSOPER or SYSASM.

ENTRIES
Entries specify the maximum number of distinct SYSDBA, SYSOPER and SYSASM users that can be stored in the password file.

This argument specifies the number of entries that you require the password file to accept. The actual number of allowable entries can be higher than the number of users, because the orapwd utility continues to assign password entries until an OS block is filled. For example, if your OS block size is 512 bytes, it holds four password entries. The number of password entries allocated is always a multiple of four.

Entries can be reused as users are added to and removed from the password file. When you exceed the allocated number of password entries, you must create a new password file. To avoid this necessity, allocate a number of entries that is larger than you think you will ever need.

FORCE
(Optional) If Y, permits overwriting an existing password file. An error will be returned if password file of the same name already exists and this argument is omitted or set to N.

IGNORECASE
(Optional) If Y, passwords are treated as case-insensitive i.e. case is ignored when comparing the password that the user supplies during login with the password in the password file.

NOSYSDBA
(Optional) For Oracle Data Vault installations.

Granting SYSDBA or SYSOPER or SYSASM privileges


Use the V$PWFILE_USERS view to see the users who have been granted SYSDBA or SYSOPER or SYSASM system privileges for a database.


SQL> select * from v$pwfile_users;
USERNAME SYSDBA SYSOPER SYSASM
-------- ------ ------- ------
SYS TRUE TRUE FALSE
The columns displayed by the view V$PWFILE_USERS are:


Column Description

USERNAME
This column contains the name of the user that is recognized by the password file.
SYSDBAIf the value of this column is TRUE, then the user can log on with SYSDBA system privilege.
SYSOPER If the value of this column is TRUE, then the user can log on with SYSOPER system privilege.
SYSASMIf the value of this column is TRUE, then the user can log on with SYSASM system privilege.



If orapwd has not yet been executed or password file is not available, attempting to grant SYSDBA or SYSOPER or SYSASM privileges will result in the following error:
SQL> grant sysdba to satya;
ORA-01994: GRANT failed: cannot add users to public password file

If your server is using an EXCLUSIVE password file, use the GRANT statement to grant the SYSDBA or SYSOPER or SYSASM system privilege to a user, as shown in the following example:
SQL> grant sysdba to satya;

SQL> select * from v$pwfile_users;
USERNAME SYSDBA SYSOPER SYSASM
-------- ------ ------- ------
SYS TRUE TRUE FALSE
SATYA TRUE FALSE FALSE

SQL> grant sysoper to satya;
SQL> select * from v$pwfile_users;
USERNAME SYSDBA SYSOPER SYSASM
-------- ------ ------- ------
SYS TRUE TRUE FALSE
SATYA TRUE TRUE FALSE

SQL> grant sysasm to satya;
SQL> select * from v$pwfile_users;
USERNAME SYSDBA SYSOPER SYSASM
-------- ------ ------- ------
SYS TRUE TRUE FALSE
SATYA TRUE TRUE TRUE

When you grant SYSDBA or SYSOPER or SYSASM privileges to a user, that user's name and privilege information are added to the password file. If the server does not have an EXCLUSIVE password file (i.e. if the initialization parameter REMOTE_LOGIN_PASSWORDFILE is NONE or SHARED, or the password file is missing), Oracle issues an error if you attempt to grant these privileges.

Use the REVOKE statement to revoke the SYSDBA or SYSOPER or SYSASM system privilege from a user, as shown in the following example:
SQL> revoke sysoper from satya;

SQL> select * from v$pwfile_users;
USERNAME SYSDBA SYSOPER SYSASM
-------- ------ ------- ------
SYS TRUE TRUE FALSE
SATYA TRUE FALSE TRUE

A user's name remains in the password file only as long as that user has at least one of these three privileges. If you revoke all 3 privileges, Oracle removes the user from the password file.

Because SYSDBA, SYSOPER and SYSASM are the most powerful database privileges, the WITH ADMIN OPTION is not used in the GRANT statement. That is, the grantee cannot in turn grant the SYSDBA or SYSOPER or SYSASM privilege to another user. Only a user currently connected as SYSDBA can grant or revoke another user's SYSDBA or SYSOPER or SYSASM system privileges. These privileges cannot be granted to roles, because roles are available only after database startup.

If you receive the file full error (ORA-01996) when you try to grant SYSDBA or SYSOPER or SYSASM system privileges to a user, you must create a larger password file and regrant the privileges to the users.

Removing Password File
If you determine that you no longer require a password file to authenticate users, you can delete the password file and then optionally reset the REMOTE_LOGIN_PASSWORDFILE initialization parameter to NONE. After you remove this file, only those users who can be authenticated by the OS can perform SYSDBA or SYSOPER or SYSASM database administration operations.

Source: Internet