Are you ready to extend your on-premises Active Directory to Amazon Web Services (AWS) to remove undifferentiated heavy lifting? Would you like to maintain a highly available Directory Service for your applications? Companies who have already set up integration with Okta Identity Cloud for external or internal applications require Active Directory objects to be synced to Okta for authentication. To achieve centralized access for on-premises and cloud applications, you can extend your on-premises Active Directory to AWS Managed Microsoft Active Directory (AD) using a trust relationship.
This blog shows an architecture pattern that you can use to synchronize your on-premises AD and AWS Managed AD objects. You can use Okta Identity Cloud using an Okta AD agent for syncing users and groups. The Okta AD agent can be installed and configured on a domain-joined on-premises server or an Amazon EC2 instance on AWS (see Figure 1).
AWS Directory Service lets you run Microsoft Active Directory (AD) as a managed service, and is powered by Windows Server 2012 R2. When you select and launch this directory type, it is created as a highly available pair of domain controllers connected to your Amazon Virtual Private Cloud (VPC). The domain controllers run in different Availability Zones in an AWS Region of your choice.
Okta is an enterprise-grade identity management service, which is compatible with many on-premises and cloud applications. The Okta AD agent enables you to integrate Okta with your on-premises AD. This way you can integrate your SaaS applications and your AD instances with Okta. You can simplify and centralize user management and share user credentials with other integrated cloud and on-premises applications.
Network connectivity between corporate data center and AWS Regions
Before getting started with configuring a trust relationship with on-premises AD and AWS managed AD, be sure you’ve read and understand the prerequisites for setting up trust. For example, it is highly recommended to have a VPN or AWS Direct Connect circuit in place between your VPC and your on-premises environment. To create a resilient VPN connection, refer to the Site-to-Site VPN User Guide.
AWS Site-to-Site VPN is a fully managed service that uses IP security (IPsec) tunnels to create a secure connection between your data center or branch office, and your AWS resources. When using Site-to-Site VPN, you can connect to Amazon VPC and also AWS Transit Gateway. Two tunnels per connection are used for increased redundancy. You can also create a dedicated or a hosted connection using AWS Direct Connect.
Trust relationship between on-premises AD and AWS Managed AD
A trust relationship is a link between two different domains. For example, a one-way trust scenario allows the user accounts from the trusted domain to access resources in the trusting domain. In a two-way trust scenario, user accounts and resources can be passed between the two domains bidirectionally. A two-way trust relationship is commonly set up between on-premises AD and AWS Managed AD to extend authentication. This is used for any directory-aware workloads in the AWS Cloud, providing users and groups access to resources in either domain using single sign-on (SSO).
AWS Managed Microsoft Active Directory (AD) supports external and forest trust relationships with your existing on-premises domain in all three trust relationship directions:
- One-way incoming
- One-way outgoing
- Two-way bidirectional
To create a trust relationship, follow these steps:
- Prepare your on-premises domain for the trust relationship. This includes preparing your firewall configuration, enable Kerberos pre-authentication, and configuring conditional forwarders.
- Prepare your AWS Managed Microsoft AD for the trust relationship. This includes configuring your VPC subnets, security groups, and enabling Kerberos pre-authentication.
- Create the trust relationship between your on-premises AD and your AWS Managed Microsoft Active Directory (AD).
Install and configure Okta agent
Download and install Okta AD agent on your Amazon EC2 instance, which should be domain-joined with AWS Managed AD. One Okta AD agent can associate with multiple domains. Once the trust has been set up between on-premises AD and AWS Managed AD, you can associate multiple domains under the same Okta AD agent on Amazon EC2, instead of hosting and managing separate Okta AD agent servers in your own data center and AWS.
For a highly available architecture, a redundant Okta AD agent running in your corporate data center is recommended. This will help you avoid the impact of network connectivity failure between data centers and AWS Regions. Okta recommends installing multiple Okta AD agents on each domain server to achieve high availability and failover protection.
Read Okta AD integration step-by-step setup for installing and configuring Okta agent.
Validate AD objects
Once the Okta agent is installed and configured on the Amazon EC2 instance, log in to the Okta admin console. Under the provisioning to Okta tab, do a full import of users from AWS Managed AD (see Figure 2, Figure 3). The subsequent objects synchronization will be done through scheduled import with a minimum interval of one hour. After the import is done, if there are any user account overlaps between AWS Managed AD and Okta, manually assign the AD users to Okta users. You can create matching rules to automatically map the users from AD to Okta. Read Import AD users to Okta.
Matching rules are used in the import of users from all apps and directories that provide importing. If there is an existing Okta account, AD allows you to import and confirm users automatically (see Figure 4).
You can import groups from any forest or domain connected to Okta. The Okta AD Agent detects all groups in the domain or the organizational units (OUs) that you select. If you register an Okta AD Agent for more than one domain and you have the root OU selected for all domains, all groups will be imported. Read Import AD Groups to Okta to synchronize groups from AD to Okta.
Synchronize passwords to Okta
When you sign in to Okta using your organization’s AD credentials, the authentication process is delegated to the connected on-premises AD. Okta does not see or store the credentials.
In some cases, the credentials must be synchronized from a directory across Okta to an application. If a user changes the password stored in Active Directory and then tries to access applications using the same single sign-on session, they will receive a password error message. This is because the new password has not been synchronized to the application, so a new sign-in process is required for password validation.
To avoid a disruptive user experience, use the Okta AD Password Sync Agent to synchronize passwords from AD to Okta and to integrated apps. The Okta AD Password Sync Agent will track password changes in AD and then synchronize to Okta.
For more details on the password synchronization and password reset workflow, you can read step-by-step instructions on Synchronize passwords from Active Directory to Okta.
In this blog post, we discussed a way for synchronizing users and credentials from on-premises Active Directory and AWS Managed AD to Okta Identity Cloud. With synchronization, you can centralize access of cloud and on-premises applications and provide seamless access to AD-aware services within AWS.
Customers can also migrate on-premises AD to AWS using Active Directory Migration Tool (ADMT) along with the Password Export Server (PES) service.