# Setting up Kerberos authentication for Amazon RDS for Db2 DB instances
You use AWS Directory Service for Microsoft Active Directory (AWS Managed Microsoft AD) to set up Kerberos authentication for an RDS for Db2 DB instance. To set up Kerberos authentication, follow these steps:
**Topics**
+ [Step 1: Create a directory using AWS Managed Microsoft AD](#db2-kerberos-setting-up.create-directory)
+ [Step 2: Create a trust](#db2-kerberos-setting-up-create-forest-trust)
+ [Step 3: Create an IAM role for Amazon RDS to access Directory Service](#db2-kerberos-setting-up-create-iam-role)
+ [Step 4: Create and configure users](#db2-kerberos-setting-up.create-users)
+ [Step 5: Create an RDS for Db2 admin group in AWS Managed Microsoft AD](#db2-kerberos-setting-up-vpc-peering)
+ [Step 6: Modify DB parameter](#db2-kerberos-setting-up-modify-db-parameter)
+ [Step 7: Create or modify an RDS for Db2 DB instance](#db2-kerberos-setting-up-create-modify)
+ [Step 8: Retrieve the Active Directory group SID in PowerShell](#db2-kerberos-setting-up-retrieve-ad-group-sid)
+ [Step 9: Add SID to GroupName mappings to your RDS for Db2 DB instance](#db2-kerberos-setting-up-add-sid-group-mapping)
+ [Step 10: Configure a Db2 client](#db2-kerberos-setting-up-create-logins)
## Step 1: Create a directory using AWS Managed Microsoft AD
Directory Service creates a fully managed Active Directory in the AWS Cloud. When you create an AWS Managed Microsoft AD directory, Directory Service creates two domain controllers and DNS servers for you. The directory servers are created in different subnets in a VPC. This redundancy helps ensure that your directory remains accessible even if a failure occurs.
When you create an AWS Managed Microsoft AD directory, Directory Service performs the following tasks on your behalf:
+ Sets up an Active Directory within your VPC.
+ Creates a directory administrator account with the username `Admin` and the specified password. You use this account to manage your directory.
**Important**
Make sure to save this password. Directory Service doesn't store this password, and it can't be retrieved or reset.
+ Creates a security group for the directory controllers. The security group must permit communication with the RDS for Db2 DB instance.
When you launch AWS Directory Service for Microsoft Active Directory, AWS creates an organizational unit (OU) that contains all of your directory's objects. This OU, which has the NetBIOS name that you entered when you created your directory, is located in the domain root. The domain root is owned and managed by AWS.
The `Admin` account that was created with your AWS Managed Microsoft AD directory has permissions for the most common administrative activities for your OU:
+ Create, update, or delete users.
+ Add resources to your domain such as file or print servers, and then assign permissions for those resources to users in your OU.
+ Create additional OUs and containers.
+ Delegate authority.
+ Restore deleted objects from the Active Directory Recycle Bin.
+ Run Active Directory and Domain Name Service (DNS) modules for Windows PowerShell on the Directory Service.
The `Admin` account also has rights to perform the following domain-wide activities:
+ Manage DNS configurations (add, remove, or update records, zones, and forwarders).
+ View DNS event logs.
+ View security event logs.
**To create a directory with AWS Managed Microsoft AD**
1. Sign in to the AWS Management Console and open the Directory Service console at [https://console.aws.amazon.com/directoryservicev2/](https://console.aws.amazon.com/directoryservicev2/).
1. Choose **Set up directory**.
1. Choose **AWS Managed Microsoft AD**. AWS Managed Microsoft AD is the only option currently supported for use with Amazon RDS.
1. Choose ******Next******.
1. On the ******Enter directory information****** page, provide the following information:
+ **Edition** – Choose the edition that meets your requirements.
+ **Directory DNS name**** **– The fully qualified name for the directory, such as `corp.example.com`.
+ **Directory NetBIOS name**** **– An optional short name for the directory, such as `CORP`.
+ **Directory description** – An optional description for the directory.
+ **Admin password**** **– The password for the directory administrator. The directory creation process creates an administrator account with the username `Admin` and this password.
The directory administrator password can't include the word "admin." The password is case-sensitive and must be 8–64 characters in length. It must also contain at least one character from three of the following four categories:
+ Lowercase letters (a–z)
+ Uppercase letters (A–Z)
+ Numbers (0–9)
+ Nonalphanumeric characters (\$1\$1@\$1\$1%^&\$1\$1-\$1=`\$1\$1()\$1\$1[]:;"'<>,.?/)
+ Confirm password – Retype the administrator password.
**Important**
Make sure that you save this password. Directory Service doesn't store this password, and it can't be retrieved or reset.
1. Choose **Next**.
1. On the **Choose VPC and subnets** page, provide the following information:
+ **VPC** – Choose the VPC for the directory. You can create the RDS for Db2 DB instance in this same VPC or in a different VPC.
+ **Subnets** – Choose the subnets for the directory servers. The two subnets must be in different Availability Zones.
1. Choose **Next**.
1. Review the directory information. If changes are needed, choose **Previous** and make the changes. When the information is correct, choose **Create directory**.
![\[The Review & create window during directory creation in the Directory Service console.\]](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/images/db2-create-ADS-directory.png)
It takes several minutes for the directory to be created. When it has been successfully created, the **Status** value changes to **Active**.
To see information about your directory, choose the directory ID under **Directory ID**. Make a note of the **Directory ID** value. You need this value when you create or modify your RDS for Db2 DB instance.
![\[The Directory details section with Directory ID in the Directory Service console.\]](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/images/db2-ADS-directory-details.png)
## Step 2: Create a trust
If you plan to use AWS Managed Microsoft AD only, skip to [Step 3: Create an IAM role for Amazon RDS to access Directory Service](#db2-kerberos-setting-up-create-iam-role).
To enable Kerberos authentication using your self-managed Active Directory, you must create a forest trust relationship between your self-managed Active Directory and the . A forest trust is a trust relationship between a Microsoft AD and a self-managed Active Directory and the AWS Managed Microsoft AD created in the previous step. The trust can also be two-way, where both Active Directories trust each other. For more information about setting up forest trusts using Directory Service, see [When to create a trust relationship](https://docs.aws.amazon.com/directoryservice/latest/admin-guide/ms_ad_tutorial_setup_trust.html) in the *AWS Directory Service Administration Guide*.
## Step 3: Create an IAM role for Amazon RDS to access Directory Service
For Amazon RDS to call Directory Service for you, your AWS account needs an IAM role that uses the managed IAM policy `AmazonRDSDirectoryServiceAccess`. This role allows Amazon RDS to make calls to Directory Service.
When you create a DB instance using the AWS Management Console and your console user account has the `iam:CreateRole` permission, the console creates the needed IAM role automatically. In this case, the role name is `rds-directoryservice-kerberos-access-role`. Otherwise, you must create the IAM role manually. When you create this IAM role, choose `Directory Service`, and attach the AWS managed policy `AmazonRDSDirectoryServiceAccess` to it.
For more information about creating IAM roles for a service, see [Creating a role to delegate permissions to an AWS service](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-service.html) in the *IAM User Guide*.
**Note**
The IAM role used for Windows Authentication for RDS for Microsoft SQL Server can't be used for RDS for Db2.
As an alternative to using the `AmazonRDSDirectoryServiceAccess` managed policy, you can create policies with the required permissions. In this case, the IAM role must have the following IAM trust policy:
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Sid": "",
"Effect": "Allow",
"Principal": {
"Service": [
"directoryservice.rds.amazonaws.com",
"rds.amazonaws.com"
]
},
"Action": "sts:AssumeRole"
}
]
}
```
------
The role must also have the following IAM role policy:
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Action": [
"ds:DescribeDirectories",
"ds:AuthorizeApplication",
"ds:UnauthorizeApplication",
"ds:GetAuthorizedApplicationDetails"
],
"Effect": "Allow",
"Resource": "*"
}
]
}
```
------
## Step 4: Create and configure users
You can create users by using the Active Directory Users and Computers tool. This is one of the Active Directory Domain Services and Active Directory Lightweight Directory Services tools. For more information, see [Add Users and Computers to the Active Directory domain](https://learn.microsoft.com/en-us/troubleshoot/windows-server/identity/create-an-active-directory-server#add-users-and-computers-to-the-active-directory-domain) in the Microsoft documentation. In this case, users are individuals or other entities, such as their computers, that are part of the domain and whose identities are being maintained in the directory.
To create users in an Directory Service directory, you must be connected to a Windows-based Amazon EC2 instance that's a member of the Directory Service directory. At the same time, you must be signed in as a user that has privileges to create users. For more information, see [Create a user](https://docs.aws.amazon.com/directoryservice/latest/admin-guide/ms_ad_manage_users_groups_create_user.html) in the *AWS Directory Service Administration Guide*.
## Step 5: Create an RDS for Db2 admin group in AWS Managed Microsoft AD
RDS for Db2 doesn't support Kerberos authentication for the master user or the two Amazon RDS reserved users `rdsdb` and `rdsadmin`. Instead, you need to create a new group called `masterdba` in AWS Managed Microsoft AD. For more information, see [Create a Group Account in Active Directory](https://learn.microsoft.com/en-us/windows/security/operating-system-security/network-security/windows-firewall/create-a-group-account-in-active-directory) in the Microsoft documentation. Any users that you add to this group will have master user privileges.
After you enable Kerberos authentication, the master user loses the `masterdba` role. As a result, the master user won't be able to access the instance local user group membership unless you disable Kerberos authentication. To continue to use the master user with password login, create a user on AWS Managed Microsoft AD with the same name as the master user. Then, add that user to the group `masterdba`.
## Step 6: Modify DB parameter
If you plan to use AWS Managed Microsoft AD only, skip to [Step 7: Create or modify an RDS for Db2 DB instanceStep 7: Create or modify a DB instance](#db2-kerberos-setting-up-create-modify).
To enable Kerberos authentication using your self-managed Active Directory, you must set the parameter `rds.active_directory_configuration` to `AWS_MANAGED_AD_WITH_TRUST` in your parameter group. By default, this parameter is set to `AWS_MANAGED_AD` for using AWS Managed Microsoft AD only.
For information about modifying DB parameters, see [Modifying the parameters in parameter groups](db2-supported-parameters.md#db2-modifying-parameter-group-parameters).
## Step 7: Create or modify an RDS for Db2 DB instance
Create or modify an RDS for Db2 DB instance for use with your directory. You can use the AWS Management Console, the AWS CLI, or the RDS API to associate a DB instance with a directory. You can do this in one of the following ways:
+ Create a new RDS for Db2 DB instance using the console, the [https://docs.aws.amazon.com/cli/latest/reference/rds/create-db-instance.html](https://docs.aws.amazon.com/cli/latest/reference/rds/create-db-instance.html) command, or the [https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBInstance.html](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBInstance.html) API operation. For instructions, see [Creating an Amazon RDS DB instance](USER_CreateDBInstance.md).
+ Modify an existing RDS for Db2 DB instance using the console, the [https://docs.aws.amazon.com/cli/latest/reference/rds/modify-db-instance.html](https://docs.aws.amazon.com/cli/latest/reference/rds/modify-db-instance.html) command, or the [ModifyDBInstance](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_ModifyDBInstance.html) API operation. For instructions, see [Modifying an Amazon RDS DB instance](Overview.DBInstance.Modifying.md).
+ Restore an RDS for Db2 DB instance from a DB snapshot using the console, the [https://docs.aws.amazon.com/cli/latest/reference/rds/restore-db-instance-from-db-snapshot.html](https://docs.aws.amazon.com/cli/latest/reference/rds/restore-db-instance-from-db-snapshot.html) command, or the [https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_RestoreDBInstanceFromDBSnapshot.html](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_RestoreDBInstanceFromDBSnapshot.html) API operation. For instructions, see [Restoring to a DB instance](USER_RestoreFromSnapshot.md).
+ Restore an RDS for Db2 DB instance to a point-in-time using the console, the [https://docs.aws.amazon.com/cli/latest/reference/rds/restore-db-instance-to-point-in-time.html](https://docs.aws.amazon.com/cli/latest/reference/rds/restore-db-instance-to-point-in-time.html) command, or the [https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_RestoreDBInstanceToPointInTime.html](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_RestoreDBInstanceToPointInTime.html) API operation. For instructions, see [Restoring a DB instance to a specified time for Amazon RDS](USER_PIT.md).
Kerberos authentication is only supported for RDS for Db2 DB instances in a VPC. The DB instance can be in the same VPC as the directory, or in a different VPC. The DB instance must use a security group that allows ingress and egress within the directory's VPC so the DB instance can communicate with the directory.
### Console
When you use the console to create, modify, or restore a DB instance, choose **Password and Kerberos authentication** in the **Database authentication** section. Then choose **Browse Directory**. Select the directory or choose **Create directory** to use the Directory Service.
![\[The Database authentication section with Password and Kerberos authentication selected in the Amazon RDS console.\]](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/images/db2-database-authentication-directory.png)
### AWS CLI
When you use the AWS CLI, the following parameters are required for the DB instance to be able to use the directory that you created:
+ For the `--domain` parameter, use the domain identifier ("`d-*`" identifier) generated when you created the directory.
+ For the `--domain-iam-role-name` parameter, use the role you created that uses the managed IAM policy `AmazonRDSDirectoryServiceAccess`.
The following example modifies a DB instance to use a directory. Replace the following placeholders in the example with your own values:
+ *db\$1instance\$1name* – The name of your RDS for Db2 DB instance.
+ *directory\$1id* – The ID of the AWS Directory Service for Microsoft Active Directory directory that you created.
+ *role\$1name* – The name of the IAM role that you created.
```
aws rds modify-db-instance --db-instance-identifier db_instance_name --domain d-directory_id --domain-iam-role-name role_name
```
**Important**
If you modify a DB instance to enable Kerberos authentication, reboot the DB instance after making the change.
## Step 8: Retrieve the Active Directory group SID in PowerShell
A security ID (SID) uniquely identifies a security principal or security group. When a security group or account is created in Active Directory, Active Directory assigns a SID to the group. To retrieve the AD security group SID from Active Directory, use the `Get-ADGroup` cmdlet in a Windows client machine that is part of the Active Directory domain. The `Identity` parameter specifies the Active Directory group name that you want the SID for.
The following example returns the SID of the Active Directory group `adgroup1`.
```
C:\Users\Admin> Get-ADGroup -Identity adgroup1 | select SID
SID
-----------------------------------------------
S-1-5-21-3168537779-1985441202-1799118680-1612
```
You must generate this mapping for all the groups that are relevant to the database.
## Step 9: Add SID to GroupName mappings to your RDS for Db2 DB instance
You need to add the SID to GroupName mappings created in the previous step to your RDS for Db2 DB instance. For each mapping, call the following stored procedure. Replace the *SID* and *group\$1name* with your own information.
```
db2 connect to rdsadmin
db2 "call rdsadmin.set_sid_group_mapping(?, 'SID','group_name')"
```
For more information, see [rdsadmin.set\$1sid\$1group\$1mapping](db2-sp-granting-revoking-privileges.md#db2-sp-set-sid-group-mapping).
For information about checking the task status, see [rdsadmin.get\$1task\$1status](db2-user-defined-functions.md#db2-udf-get-task-status).
## Step 10: Configure a Db2 client
**To configure a Db2 client**
1. Create an **/etc/krb5.conf** file (or equivalent) to point to the domain.
**Note**
For Windows operating systems, create a **C:\$1windows\$1krb5.ini** file.
1. Verify that traffic can flow between the client host and Directory Service. Use a network utility such as Netcat for the following tasks:
1. Verify traffic over DNS for port 53.
1. Verify traffic over TCP/UDP for port 53 and for Kerberos, which includes ports 88 and 464 for Directory Service.
1. Verify that traffic can flow between the client host and the DB instance over the database port. You can use the command `db2` to connect and access the database.
The following example is /etc/krb5.conf file content for AWS Managed Microsoft AD:
```
[libdefaults]
default_realm = EXAMPLE.COM
[realms]
EXAMPLE.COM = {
kdc = example.com
admin_server = example.com
}
[domain_realm]
.example.com = EXAMPLE.COM
example.com = EXAMPLE.COM
```