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AWS Organizations
User Guide

Authentication and Access Control for AWS Organizations

Access to AWS Organizations requires credentials. Those credentials must have permissions to access AWS resources, such as an Amazon Simple Storage Service (Amazon S3) bucket, an Amazon Elastic Compute Cloud (Amazon EC2) instance, or an AWS Organizations organizational unit (OU). The following sections provide details on how you can use AWS Identity and Access Management (IAM) to help secure access to your organization and control who can administer it.

To determine who can administer which parts of your organization, AWS Organizations uses the same IAM-based permissions model as other AWS services. As an administrator in the master account of an organization, you can grant IAM-based permissions to perform AWS Organizations tasks by attaching policies to users, groups, and roles in the master account. Those policies specify the actions that those principals can perform. You attach an IAM permissions policy to a group that the user is a member of or directly to a user or role. As a best practice, we recommend that you attach policies to groups instead of users. You also have the option to grant full administrator permissions to others.

For most administrator operations for AWS Organizations, you need to attach permissions to users or groups in the master account. If a user in a member account needs to perform administrator operations for your organization, you need to grant the AWS Organizations permissions to an IAM role in the master account and enable the user in the member account to assume the role. For general information about IAM permissions policies, see Overview of IAM Policies in the IAM User Guide.

Authentication

You can access AWS as any of the following types of identities:

  • AWS account root user – When you sign up for AWS, you provide an email address and password that is associated with your AWS account. These are your root credentials, and they provide complete access to all of your AWS resources.

    Important

    For security reasons, we recommend that you use the root credentials only to create an administrator user, which is an IAM user with full permissions to your AWS account. Then you can use this administrator user to create other IAM users and roles with limited permissions. For more information, see IAM Best Practices and Creating Your First IAM Admin User and Group in the IAM User Guide.

  • IAM user – An IAM user is simply an identity within your AWS account that has specific custom permissions (for example, permissions to create a file system in Amazon Elastic File System). You can use an IAM user name and password to sign in to secure AWS webpages like the AWS Management Console, AWS Discussion Forums, or the AWS Support Center.

    In addition to a user name and password, you can generate access keys for each user. You can use these keys when you access AWS services programmatically, either through one of the several SDKs or by using the AWS Command Line Interface (AWS CLI). The SDK and AWS CLI tools use the access keys to cryptographically sign your request. If you don't use the AWS tools, you must sign the request yourself. AWS Organizations supports Signature Version 4, a protocol for authenticating inbound API requests. For more information about authenticating requests, see Signature Version 4 Signing Process in the AWS General Reference.

  • IAM role – An IAM role is another IAM identity you can create in your account that has specific permissions. It is similar to an IAM user, but it isn't associated with a specific person. An IAM role allows you to obtain temporary access keys that can access AWS services and resources. IAM roles with temporary credentials are useful in the following situations:

    • Federated user access – Instead of creating an IAM user, you can use preexisting user identities from AWS Directory Service, your enterprise user directory, or a web identity provider. These are known as federated users. AWS assigns a role to a federated user when access is requested through an identity provider. For more information about federated users, see Federated Users and Roles in the IAM User Guide.

    • Cross-account access – You can use an IAM role in your account to grant another AWS account permissions to access your account's resources. For an example, see Tutorial: Delegate Access Across AWS Accounts Using IAM Roles in the IAM User Guide.

    • AWS service access – You can use an IAM role in your account to grant an AWS service permissions to access your account's resources. For example, you can create a role that allows Amazon Redshift to access an Amazon S3 bucket on your behalf and then load data stored in the bucket into an Amazon Redshift cluster. For more information, see Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide.

    • Applications running on Amazon EC2 – Instead of storing access keys in the EC2 instance for use by applications running on the instance and making AWS API requests, you can use an IAM role to manage temporary credentials for these applications. To assign an AWS role to an EC2 instance and make it available to all of its applications, you can create an instance profile that is attached to the instance. An instance profile contains the role and enables programs running on the EC2 instance to get temporary credentials. For more information, see Using Roles for Applications on Amazon EC2 in the IAM User Guide.

Access Control

You can have valid credentials to authenticate your requests, but unless you have permissions, you can't administer or access AWS Organizations resources. For example, you must have permissions to create an OU or to attach a service control policy (SCP) to an account.

The following sections describe how to manage permissions for AWS Organizations. We recommend that you read the overview first.