# Seamlessly join an Amazon EC2 Linux instance to your Simple AD Active Directory
This procedure seamlessly joins an Amazon EC2 Linux instance to your Simple AD Active Directory.
The following Linux instance distributions and versions are supported:
+ Amazon Linux AMI 2018.03.0
+ Amazon Linux 2 (64-bit x86)
+ Red Hat Enterprise Linux 8 (HVM) (64-bit x86)
+ Ubuntu Server 18.04 LTS & Ubuntu Server 16.04 LTS
+ CentOS 7 x86-64
+ SUSE Linux Enterprise Server 15 SP1
**Note**
Distributions prior to Ubuntu 14 and Red Hat Enterprise Linux 7 and 8 do not support the seamless domain join feature.
## Prerequisites
Before you can set up seamless domain join to a Linux instance, you need to complete the procedures in this section.
### Select your seamless domain join service account
You can seamlessly join Linux computers to your Simple AD domain. To do that, you must create a user account with create computer account permissions to join the computers to the domain. Although members of the *Domain Admins* or other groups may have sufficient privileges to join computers to the domain, we do not recommend this. As a best practice, we recommend you use a service account that has the minimum privileges necessary to join the computers to the domain.
For information about how to process and delegate permissions to your service account for computer account creation, see [Delegate privileges to your service account](ad_connector_getting_started.md#connect_delegate_privileges).
### Create the secrets to store the domain service account
You can use AWS Secrets Manager to store the domain service account. For more information, see [Create an AWS Secrets Manager secret](https://docs.aws.amazon.com//secretsmanager/latest/userguide/create_secret.html).
**Note**
There are fees associated with Secrets Manager. For more information see, [Pricing](https://docs.aws.amazon.com//secretsmanager/latest/userguide/intro.html#asm_pricing) in the *AWS Secrets Manager User Guide*.
**To create secrets and store the domain service account information**
1. Sign in to the AWS Management Console and open the AWS Secrets Manager console at [https://console.aws.amazon.com/secretsmanager/](https://console.aws.amazon.com/secretsmanager/).
1. Choose **Store a new secret**.
1. On the **Store a new secret** page, do the following:
1. Under **Secret type**, choose **Other type of secrets**.
1. Under **Key/value pairs**, do the following:
1. In the first box, enter **awsSeamlessDomainUsername**. On the same row, in the next box, enter the username for your service account. For example, if you used the PowerShell command previously, the service account name would be **awsSeamlessDomain**.
**Note**
You must enter **awsSeamlessDomainUsername** exactly as it is. Make sure there are not any leading or ending spaces. Otherwise the domain join will fail.
![\[In the AWS Secrets Manager console on the choose a secret type page. Other type of secret is selected under secret type and awsSeamlessDomainUsername is entered as the key value.\]](http://docs.aws.amazon.com/directoryservice/latest/admin-guide/images/secrets_manager_1.png)
1. Choose **Add row**.
1. On the new row, in the first box, enter **awsSeamlessDomainPassword**. On the same row, in the next box, enter the password for your service account.
**Note**
You must enter **awsSeamlessDomainPassword** exactly as it is. Make sure there are not any leading or ending spaces. Otherwise the domain join will fail.
1. Under **Encryption key, ** leave the default value `aws/secretsmanager`. AWS Secrets Manager always encrypts the secret when you choose this option. You also may choose a key you created.
1. Choose **Next**.
1. Under **Secret name**, enter a secret name that includes your directory ID using the following format, replacing *d-xxxxxxxxx* with your directory ID:
```
aws/directory-services/d-xxxxxxxxx/seamless-domain-join
```
This will be used to retrieve secrets in the application.
**Note**
You must enter **aws/directory-services/*d-xxxxxxxxx*/seamless-domain-join** exactly as it is but replace *d-xxxxxxxxxx* with your directory ID. Make sure that there are no leading or ending spaces. Otherwise the domain join will fail.
![\[In the AWS Secrets Manager console on the configure secret page. The secret name is entered and highlighted.\]](http://docs.aws.amazon.com/directoryservice/latest/admin-guide/images/secrets_manager_2.png)
1. Leave everything else set to defaults, and then choose **Next**.
1. Under **Configure automatic rotation**, choose **Disable automatic rotation**, and then choose **Next**.
You can turn on rotation for this secret after you store it.
1. Review the settings, and then choose **Store** to save your changes. The Secrets Manager console returns you to the list of secrets in your account with your new secret now included in the list.
1. Choose your newly created secret name from the list, and take note of the **Secret ARN** value. You will need it in the next section.
### Turn on rotation for the domain service account secret
We recommend that you regularly rotate secrets to improve your security posture.
**To turn on rotation for the domain service account secret**
+ Follow the instructions in [Set up automatic rotation for AWS Secrets Manager secrets](https://docs.aws.amazon.com/secretsmanager/latest/userguide/rotate-secrets_turn-on-for-other.html) in the *AWS Secrets Manager User Guide*.
For Step 5, use the rotation template [Microsoft Active Directory credentials](https://docs.aws.amazon.com/secretsmanager/latest/userguide/reference_available-rotation-templates.html#template-AD-password) in the *AWS Secrets Manager User Guide*.
For help, see [Troubleshoot AWS Secrets Manager rotation](https://docs.aws.amazon.com/secretsmanager/latest/userguide/troubleshoot_rotation.html) in the *AWS Secrets Manager User Guide*.
### Create the required IAM policy and role
Use the following prerequisite steps to create a custom policy that allows read-only access to your Secrets Manager seamless domain join secret (which you created earlier), and to create a new LinuxEC2DomainJoin IAM role.
#### Create the Secrets Manager IAM read policy
You use the IAM console to create a policy that grants read-only access to your Secrets Manager secret.
**To create the Secrets Manager IAM read policy**
1. Sign in to the AWS Management Console as a user that has permission to create IAM policies. Then open the IAM console at [https://console.aws.amazon.com/iam/](https://console.aws.amazon.com/iam/).
1. In the navigation pane, **Access Management**, choose **Policies**.
1. Choose **Create policy**.
1. Choose the **JSON** tab and copy the text from the following JSON policy document. Then paste it into the **JSON** text box.
**Note**
Make sure you replace the Region and Resource ARN with the actual Region and ARN of the secret that you created earlier.
```
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"secretsmanager:GetSecretValue",
"secretsmanager:DescribeSecret"
],
"Resource": [
"arn:aws:secretsmanager:us-east-1:xxxxxxxxx:secret:aws/directory-services/d-xxxxxxxxx/seamless-domain-join"
]
}
]
}
```
1. When you are finished, choose **Next**. The policy validator reports any syntax errors. For more information, see [Validating IAM policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_policy-validator.html).
1. On the **Review policy** page, enter a policy name, such as **SM-Secret-Linux-DJ-*d-xxxxxxxxxx*-Read**. Review the **Summary** section to see the permissions that your policy grants. Then choose **Create policy** to save your changes. The new policy appears in the list of managed policies and is now ready to attach to an identity.
**Note**
We recommend you create one policy per secret. Doing so ensures that instances only have access to the appropriate secret and minimizes the impact if an instance is compromised.
#### Create the LinuxEC2DomainJoin role
You use the IAM console to create the role that you will use to domain join your Linux EC2 instance.
**To create the LinuxEC2DomainJoin role**
1. Sign in to the AWS Management Console as a user that has permission to create IAM policies. Then open the IAM console at [https://console.aws.amazon.com/iam/](https://console.aws.amazon.com/iam/).
1. In the navigation pane, under **Access Management**, choose **Roles**.
1. In the content pane, choose **Create role**.
1. Under **Select type of trusted entity**, choose **AWS service**.
1. Under **Use case**, choose **EC2**, and then choose **Next**.
![\[In the IAM console on the select trusted entity page. AWS service and EC2 are selected.\]](http://docs.aws.amazon.com/directoryservice/latest/admin-guide/images/iam-console-trusted-entity.png)
1. For **Filter policies**, do the following:
1. Enter **AmazonSSMManagedInstanceCore**. Then select the check box for that item in the list.
1. Enter **AmazonSSMDirectoryServiceAccess**. Then select the check box for that item in the list.
1. Enter **SM-Secret-Linux-DJ-*d-xxxxxxxxxx*-Read** (or the name of the policy that you created in the previous procedure). Then select the check box for that item in the list.
1. After adding the three policies listed above, select **Create role**.
**Note**
AmazonSSMDirectoryServiceAccess provides the permissions to join instances to an Active Directory managed by Directory Service. AmazonSSMManagedInstanceCore provides the minimum permissions necessary to use the AWS Systems Manager service. For more information about creating a role with these permissions, and for information about other permissions and policies you can assign to your IAM role, see [Create an IAM instance profile for Systems Manager](https://docs.aws.amazon.com/systems-manager/latest/userguide/setup-instance-profile.html) in the *AWS Systems Manager User Guide*.
1. Enter a name for your new role, such as **LinuxEC2DomainJoin** or another name that you prefer in the **Role name** field.
1. (Optional) For **Role description**, enter a description.
1. (Optional) Choose **Add new tag** under **Step 3: Add tags** to add tags. Tag key-value pairs are used to organize, track, or control access for this role.
1. Choose **Create role**.
## Seamlessly join a Linux instance to your Simple AD Active Directory
**To seamlessly join your Linux instance**
1. Sign in to the AWS Management Console and open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/).
1. From the Region selector in the navigation bar, choose the same AWS Region as the existing directory.
1. On the **EC2 Dashboard**, in the **Launch instance** section, choose **Launch instance**.
1. On the **Launch an instance** page, under the **Name and Tags** section, enter the name you would like to use for your Linux EC2 instance.
1. *(Optional)* Choose **Add additional tags** to add one or more tag key-value pairs to organize, track, or control access for this EC2 instance.
1. In the **Application and OS Image (Amazon Machine Image)** section, choose a Linux AMI you wish to launch.
**Note**
The AMI used must have AWS Systems Manager (SSM Agent) version 2.3.1644.0 or higher. To check the installed SSM Agent version in your AMI by launching an instance from that AMI, see [Getting the currently installed SSM Agent version](https://docs.aws.amazon.com/systems-manager/latest/userguide/ssm-agent-get-version.html). If you need to upgrade the SSM Agent, see [Installing and configuring SSM Agent on EC2 instances for Linux](https://docs.aws.amazon.com/systems-manager/latest/userguide/sysman-install-ssm-agent.html).
SSM uses the `aws:domainJoin` plugin when joining a Linux instance to a Active Directory domain. The plugin changes the hostname for the Linux instances to the format EC2AMAZ-*XXXXXXX*. For more information about `aws:domainJoin`, see [AWS Systems Manager command document plugin reference](https://docs.aws.amazon.com//systems-manager/latest/userguide/documents-command-ssm-plugin-reference.html#aws-domainJoin) in the *AWS Systems Manager User Guide*.
1. In the **Instance type** section, choose the instance type you would like to use from **Instance type** dropdown list.
1. In the **Key pair (login)** section, you can either choose to create a new key pair or choose from an existing key pair. To create a new key pair, choose **Create new key pair**. Enter a name for the key pair and select an option for the **Key pair type** and **Private key file format**. To save the private key in a format that can be used with OpenSSH, choose **.pem**. To save the private key in a format that can be used with PuTTY, choose **.ppk**. Choose **create key pair**. The private key file is automatically downloaded by your browser. Save the private key file in a safe place.
**Important**
This is the only chance for you to save the private key file.
1. On the **Launch an instance** page, under **Network settings** section, choose **Edit**. Choose the **VPC** that your directory was created in from the **VPC -* required*** dropdown list.
1. Choose one of the public subnets in your VPC from the **Subnet** dropdown list. The subnet you choose must have all external traffic routed to an internet gateway. If this is not the case, you won't be able to connect to the instance remotely.
For more information on how to connect to a internet gateway, see [Connect to the internet using an internet gateway](https://docs.aws.amazon.com//vpc/latest/userguide/VPC_Internet_Gateway.html) in the *Amazon VPC User Guide*.
1. Under **Auto-assign public IP**, choose **Enable**.
For more information about public and private IP addressing, see [Amazon EC2 instance IP addressing](https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/using-instance-addressing.html) in the *Amazon EC2 User Guide*.
1. For **Firewall (security groups)** settings, you can use the default settings or make changes to meet your needs.
1. For **Configure storage** settings, you can use the default settings or make changes to meet your needs.
1. Select **Advanced details** section, choose your domain from the **Domain join directory** dropdown list.
**Note**
After choosing the Domain join directory, you may see:
![\[An error message when selecting your Domain join directory. There is an error with your existing SSM document.\]](http://docs.aws.amazon.com/directoryservice/latest/admin-guide/images/SSM-Error-Message.png)
This error occurs if the EC2 launch wizard identifies an existing SSM document with unexpected properties. You can do one of the following:
If you previously edited the SSM document and the properties are expected, choose close and proceed to launch the EC2 instance with no changes.
Select the delete the existing SSM document here link to delete the SSM document. This will allow for the creation of an SSM document with the correct properties. The SSM document will automatically be created when you launch the EC2 instance.
1. For **IAM instance profile**, choose the IAM role that you previously created in the prerequisites section **Step 2: Create the LinuxEC2DomainJoin role**.
1. Choose **Launch instance**.
**Note**
If you are performing a seamless domain join with SUSE Linux, a reboot is required before authentications will work. To reboot SUSE from the Linux terminal, type **sudo reboot**.