Ilmar Kerm

Oracle, databases, Linux and maybe more

I’ve been using the old good Radius authentication protocol to authenticate database accounts (created for humans) with Active Directory credentials. It may sound strange use case, specially since Oracle also advertises its own Active Directory integration (Centrally Managed Users) and also there is Kerberos. I’ve had the following problems with them:

  • CMU – in order to use Active Directory passwords, AD schema needs to be modified and AD filter installed on AD side. I think the latter removes this feature from consideration.
  • Kerberos – passwordless login is very tempting and if you get it running on Oracle side – definetly a feature to consider. But deploying at scale and maintaining it is a nightmare, almost impossible to automate.

Radius on the other hand – Windows domain controllers have Radius server built in and it is also very easy to deploy at large scale and maintain on Oracle database side.

Configure database server

First add the following to database sqlnet.ora. File /u01/app/oracle/radius.key is a simple text file containing just the Radius secret. and are my Radius servers running on Windows, both using port 1812.

# Radius authentication settings

In the database itself set parameter os_authent_prefix to empty string:

alter system set os_authent_prefix='' scope=spfile;

And create the database users IDENTIFIED EXTERNALLY, and database username must match WInodws AD username.


Configure the client

The bad thing with Radius authenticated users is that the database client must also support Radius. Oracle thick driver supports it just fine, also JDBC thin driver.

When using Oracle thick client (Instatnt client), turn on Radius authentication by adding it to sqlnet.ora:

$ cat ORACLE_CLIENT_HOME/network/admin/sqlnet.ora


After that you can use this client to log into the database using both database authenticated users and Radius authenticated users.

JDBC thin driver is a little bit trickier (tested using 21c JDBC driver)

To use Radius add the following Java VM option – but the problem with that is that you cannot use database authenticated users after turning on this option.'(RADIUS)'

If you want to use it with SQL Developer, add the following to product.conf file


As mentioned earlier this would disable database authenticated accounts, so in case of SQL Developer changing product.conf is not desirable.

Since 19c JDBC thin driver, it is also possible to change Java properties within the connection string using EasyConnect syntax:


One bug that I discovered in JDBC thin driver support for Radius (and Oracle is still working on it) – if you use Radius together with TCPS and database server has also enabled Oracle Native Encryption – you will get the following error from JDBC driver IO Error: Checksum fail

This is rather strange error, since when using TCPS – Oracle Native Encryption should be turned off automatically, but this error comes from Native encryption checksumming. To get around it, have to disable Native Encryption checksumming from the client side – which can also be done from inside the connection string.


We have hundreds of developers who need access hundreds of application schemas, deployed to multiple locations. Data is sensitive and there is a requirement that each human access must be done via a personal database account that has access to only allowed application schemas. That has always been a struggle for me how to manage all these access privileges in a nice and easy way. Since many many many different databases are involved, database itself cannot be the source of truth for the access privileges and so far we have just synchronised the access privileges from the source of truth system to all individual databases.

I think there is a better way now – Secure Application Roles.

The idea behind them is very flexible – there is no need to grant the individual roles to database users, the users need to execute a procedure (which will do all necessary validations) and then enable the role(s) for the user session.

Lets first set up a common SECURITY_MANAGER schema, that will contain all our security related code and logging.

create user security_manager no authentication
  default tablespace users
  quota 1g on users;

grant create table, create procedure to security_manager;

create table security_manager.allowed_grants (
    db_username varchar2(128) not null,
    db_role varchar2(128) not null,
    primary key (db_username,db_role)
) organization index;

create table security_manager.role_grant_log (
    grant_time timestamp default sys_extract_utc(systimestamp) not null,
    db_username varchar2(128) not null,
    granted_role varchar2(128) not null,
    is_allowed number(1) not null,
    comments varchar2(1000),
    client_host varchar2(200),
    client_ip varchar2(50),
    unified_audit_session_id varchar2(100)

Here are two helper programs, since ACTIVATE_ROLE procedure below will need to read and write to tables in SECURITY_MANAGER schema and I do not want to grant access to these tables to users directly.

-- The job of the following procedure is just logging the grant request
CREATE OR REPLACE PROCEDURE security_manager.log_role_grant
    (p_requested_role role_grant_log.granted_role%TYPE
      , p_is_allowed role_grant_log.is_allowed%TYPE
      , p_comments role_grant_log.comments%TYPE) 
ACCESSIBLE BY (activate_role) IS
    INSERT INTO role_grant_log
      (db_username, granted_role, is_allowed, comments
        , client_host, client_ip, unified_audit_session_id)
       , p_requested_role, p_is_allowed, SYS_CONTEXT('USERENV','HOST')

-- The following function just check the master autorisation table if
-- user is allowed to activate the role or not
CREATE OR REPLACE FUNCTION security_manager.is_role_allowed
    (p_username allowed_grants.db_username%TYPE
      , p_requested_role role_grant_log.granted_role%TYPE) RETURN boolean
ACCESSIBLE BY (activate_role) IS
    v_is_role_allowed NUMBER;
    SELECT COUNT(*) INTO v_is_role_allowed
    FROM allowed_grants
    WHERE db_username = p_username AND db_role = UPPER(p_requested_role);
    RETURN v_is_role_allowed = 1;

Now the security code itself. The procedure below just checks from a simple table, if the logged in user is allowed to activate the requested role or not and also logs the request. In real life it can be much more complex – the code could make a REST call to external autorisation system and ofcourse logging should be much more detailed.

NB! The procedure must be declared AUTHID CURRENT_USER – using invokers rights.

CREATE OR REPLACE PROCEDURE security_manager.activate_role
    (p_requested_role allowed_grants.db_role%TYPE
    , p_comments role_grant_log.comments%TYPE)
    v_activated_roles VARCHAR2(4000);
    -- Check if users is allowd to activate the requested role
    IF NOT is_role_allowed(SYS_CONTEXT('USERENV','SESSION_USER'), p_requested_role) THEN
        log_role_grant(upper(p_requested_role), 0, p_comments);
        raise_application_error(-20000, 'You are not allowed to activate the requested role.');
    END IF;
    -- Query all roles that are currently active for the session and append the requested role to that list
    SELECT listagg(role, ',') WITHIN GROUP (ORDER BY role) INTO v_activated_roles FROM (
        SELECT role FROM session_roles
        SELECT upper(p_requested_role) FROM dual
    -- Activate all roles
    log_role_grant(upper(p_requested_role), 1, p_comments);

Now I create the role itself and grant the role read access to one application table. Here IDENTIFIED USING clause does the magic – it tells Oracle that sec_app_role_test1 role can only be enabled by security_manager.activate_role procedure.

CREATE ROLE sec_app_role_test1
    IDENTIFIED USING security_manager.activate_role;

GRANT READ ON app1.t1 TO sec_app_role_test1;

And my developer personal account is called ILMKER and this account only needs execute privileges on my security package. In real life you would grant this execute to a common role that all developers have (in my case that custom role is called PERSONAL_ACCOUNT).

GRANT execute ON security_manager.activate_role TO ilmker;

By default ILMKER user cannot access table APP1.T1.

ILMKER SQL> SELECT * FROM session_roles;



SQL Error: ORA-00942: table or view does not exist

Lets test using my developer account ILMKER… first I try to request a role that I do not have been granted access to. No luck, I get the exception “ORA-20000: You are not allowed to activate the requested role.”

SQL> SELECT * FROM session_roles;


SQL> exec security_manager.activate_role('sec_app_role_test1', 'Jira ref: ABC-490');

ORA-20000: You are not allowed to activate the requested role.

SQL> SELECT * FROM session_roles;


SQL> SELECT * FROM app1.t1;

SQL Error: ORA-00942: table or view does not exist

After security administrator grants me the role – inserts a row to security_manager.allowed_grants table for this example and NOT executing Oracle GRANT command.

insert into security_manager.allowed_grants (db_username, db_role)
    values ('ILMKER', upper('sec_app_role_test1'));

I ask my developer to run again.

SQL> SELECT * FROM session_roles;


SQL> exec security_manager.activate_role('sec_app_role_test1', 'Jira ref: ABC-490');

PL/SQL procedure successfully completed.

SQL> SELECT * FROM session_roles;


SQL> SELECT * FROM app1.t1;
no rows selected

The developer is happy now! Role was activated in the developer session and developer was able to read the application table. All requests were also logged by SECURITY_MANAGER schema.

SQL> select * from security_manager.role_grant_log;

2023-05-12 15:05:28,478732000    ILMKER         SEC_APP_ROLE_TEST1    STH-FVFFV04QQ05R    3428220339                              0 Jira ref: ABC-490    
2023-05-12 15:10:41,923908000    ILMKER         SEC_APP_ROLE_TEST1    STH-FVFFV04QQ05R    3428220339                              1 Jira ref: ABC-490

I think this is a powerful feature to control access to data based on much more complex criteria than just DBA executing GRANT commands. Before enabling the role code can make a REST query to external autorisation system, check the client host IP, check the client authentication method, enable detailed unified auditing policies. Possibilities are endless!