Kerberos is a trusted third-party authentication system. It relies on shared secrets and presumes that the third party is secure. You can configure Oracle Database to use Kerberos authentication. below a kerberos authentication with AD user is specifying

Scenario OS Version RHEL 8, DB Version SE, DBNAME – orcl

Install the kerberos on Database server

yum install krb5-workstation krb5-libs

Required files for kerberos configuration on server

SQLNET.ORA – file where we mention the configuration details

SQLNET.KERBEROS5_CONF = /etc/krb5.conf
SQLNET.KERBEROS5_KEYTAB = /u01/app/oracle/product/19.0.0/dbhome_1/network/admin/orcldev01.keytab

Key tab file, the file that is generated from Domain controller, this file need to be provided by the windows system admin for dba to configure kerberos

orcldev01.keytab - file copy to location specified on sqlnet.ora
oklist -k /u01/app/oracle/product/19.0.0/dbhome_1/network/admin/orcldev01.keytab
Kerberos Utilities for Linux: Version - Production on 03-MAR-2021 16:25:52
Copyright (c) 1996, 2019 Oracle. All rights reserved.
Configuration file : /etc/krb5.conf.
Keytab name: FILE:/u01/app/oracle/product/19.0.0/dbhome_1/network/admin/orcldev01.keytab
KVNO Principal
---- ------------------------------------------------------------
3 oracle/orcldev01.mithun.local@mithun.LOCAL
3 oracle/orcldev01.mithun.local@mithun.LOCAL
3 oracle/orcldev01.mithun.local@mithun.LOCAL
3 oracle/orcldev01.mithun.local@mithun.LOCAL
3 oracle/orcldev01.mithun.local@mithun.LOCAL

File permission
-rw-r--r-- 1 oracle oinstall 422 Mar 18 21:04 /u01/app/oracle/product/19.0.0/dbhome_1/network/admin/orcldev01.keytab

Kerbeross Config file – File on server that having the configuration details of the Domain controller

-rw-r--r-- 1 root root 811 Mar 03 10:38 /etc/krb5.conf
vi /etc/krb5.conf.d/
default = FILE:/var/log/krb5libs.log
kdc = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmind.log
default_realm = MITHUN.LOCAL
dns_lookup_realm = true
dns_lookup_kdc = true
ticket_lifetime = 24h
renew_lifetime = 7d
forwardable = yes
kdc = mithun.local:88
admin_server = mithun.local:749
default_domain = MITHUN.LOCAL
.mithun.local = MITHUN.LOCAL
mithun.local = MITHUN.LOCAL

On database

Set the Initialization Parameters As Kerberos user names can be long, and Oracle user names are limited to 30 characters, Oracle recommends that you set the value of OS_AUTHENT_PREFIX to null in the initialization parameter file.

alter system set OS_AUTHENT_PREFIX=”” scope=both;
Setting this parameter to null overrides the default value of OPS$.

create Database user

If the user’s Kerberos principal name is longer than 30 characters, and up to 1024 characters, then create the user as follows:

SQL> CREATE USER db_user_name IDENTIFIED EXTERNALLY AS 'kerberos_principal_name'

create user mithun identified externally as “mithun.local”

grant connect, resource to mithun

okinit mithun


now u will be able to access the database

sqlplus /@orcl