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AWS Systems Manager
User Guide

Setting Up VPC Endpoints for Systems Manager

You can improve the security posture of your managed instances (including managed instances in your hybrid environment) by configuring AWS Systems Manager to use an interface VPC endpoint. Interface endpoints are powered by PrivateLink, a technology that enables you to privately access Amazon EC2 and Systems Manager APIs by using private IP addresses. PrivateLink restricts all network traffic between your managed instances, Systems Manager, and EC2 to the Amazon network (managed instances don't have access to the Internet). Also, you don't need an Internet gateway, a NAT device, or a virtual private gateway.

You are not required to configure PrivateLink, but it's recommended. For more information about PrivateLink and VPC endpoints, see Accessing AWS Services Through PrivateLink.

Before You Begin

Before you configure VPC endpoints for Systems Manager, be aware of the following restrictions and limitations.

  • VPC endpoints do not support Active Directory directory service or Amazon CloudWatch Events. If you configure your managed instances to use a VPC endpoint, you won't be able to use these services.

    Note

    This user guide might not reflect the latest developments in Active Directory directory service and CloudWatch Events. For this reason, we encourage you to check the user guides of both products for VPC endpoint support.

  • VPC endpoints currently do not support cross-region requests—ensure that you create your endpoint in the same region as your bucket. You can find the location of your bucket by using the Amazon S3 console, or by using the get-bucket-location command. Use a region-specific Amazon S3 endpoint to access your bucket; for example, mybucket.s3-us-west-2.amazonaws.com. For more information about region-specific endpoints for Amazon S3, see Amazon Simple Storage Service (S3) in Amazon Web Services General Reference. If you use the AWS CLI to make requests to Amazon S3, set your default region to the same region as your bucket, or use the --region parameter in your requests.

  • VPC endpoints only support Amazon-provided DNS through Route 53. If you want to use your own DNS, you can use conditional DNS forwarding. For more information, see DHCP Options Sets in the Amazon VPC User Guide.

  • The security group attached to the VPC endpoint must allow incoming connections on port 443 from the private subnet of the managed instance. If incoming connections are not allowed, then the managed instance cannot connect to the SSM and EC2 endpoints.

Creating VPC EndPoints for Systems Manager

Use the following procedure to create three separate VPC endpoints for Systems Manager. All three endpoints are required for Systems Manager to work in a VPC. This procedure links to related procedures in the Amazon VPC User Guide.

To create VPC endpoints for Systems Manager

  1. Use Creating an Interface Endpoint to create the following endpoints:

    • com.amazonaws.region.ssm: The endpoint for the Systems Manager service.

    • com.amazonaws.region.ec2messages: Systems Manager uses this endpoint to make calls from SSM Agent to the Systems Manager service.

    • com.amazonaws.region.ec2: If you're using Systems Manager to create VSS-enabled snapshots, you need to ensure that you have an endpoint to the EC2 service. Without the EC2 endpoint defined, a call to enumerate attached EBS volumes fails, which causes the Systems Manager command to fail. For more information about using Systems Manager to create VSS-enabled snapshots, see Using Run Command to Take VSS-Enabled Snapshots of EBS Volumes.

    region represents the region identifier for an AWS region supported by AWS Systems Manager, such as us-east-2 for the US East (Ohio) Region. For a list of supported region values, see the Region column in the AWS Systems Manager table of regions and endpoints in the AWS General Reference.

  2. Use Creating a Gateway Endpoint to create an endpoint for Amazon S3. Systems Manager uses this endpoint to upload Amazon S3 output logs, and to update SSM Agent.