# How Amazon DynamoDB works with IAM
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Before you use IAM to manage access to DynamoDB, learn what IAM features are available to use with DynamoDB.






| IAM feature | DynamoDB support | 
| --- | --- | 
|  [Identity-based policies](#security_iam_service-with-iam-id-based-policies)  |   Yes  | 
|  [Resource-based policies](#security_iam_service-with-iam-resource-based-policies)  |   Yes  | 
|  [Policy actions](#security_iam_service-with-iam-id-based-policies-actions)  |   Yes  | 
|  [Policy resources](#security_iam_service-with-iam-id-based-policies-resources)  |   Yes  | 
|  [Policy condition keys](#security_iam_service-with-iam-id-based-policies-conditionkeys)  |   Yes  | 
|  [ACLs](#security_iam_service-with-iam-acls)  |   No   | 
|  [ABAC (tags in policies)](#security_iam_service-with-iam-tags)  |   Yes  | 
|  [Temporary credentials](#security_iam_service-with-iam-roles-tempcreds)  |   Yes  | 
|  [Principal permissions](#security_iam_service-with-iam-principal-permissions)  |   Yes  | 
|  [Service roles](#security_iam_service-with-iam-roles-service)  |   Yes  | 
|  [Service-linked roles](#security_iam_service-with-iam-roles-service-linked)  |   Yes  | 

To get a high-level view of how DynamoDB and other AWS services work with most IAM features, see [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.

## Identity-based policies for DynamoDB
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**Supports identity-based policies:** Yes

Identity-based policies are JSON permissions policy documents that you can attach to an identity, such as an IAM user, group of users, or role. These policies control what actions users and roles can perform, on which resources, and under what conditions. To learn how to create an identity-based policy, see [Define custom IAM permissions with customer managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_create.html) in the *IAM User Guide*.

With IAM identity-based policies, you can specify allowed or denied actions and resources as well as the conditions under which actions are allowed or denied. To learn about all of the elements that you can use in a JSON policy, see [IAM JSON policy elements reference](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements.html) in the *IAM User Guide*.

### Identity-based policy examples for DynamoDB
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To view examples of DynamoDB identity-based policies, see [Identity-based policy examples for Amazon DynamoDB](security_iam_id-based-policy-examples.md).

## Resource-based policies within DynamoDB
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**Supports resource-based policies:** Yes

Resource-based policies are JSON policy documents that you attach to a resource. Examples of resource-based policies are IAM *role trust policies* and Amazon S3 *bucket policies*. In services that support resource-based policies, service administrators can use them to control access to a specific resource. For the resource where the policy is attached, the policy defines what actions a specified principal can perform on that resource and under what conditions. You must [specify a principal](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html) in a resource-based policy. Principals can include accounts, users, roles, federated users, or AWS services.

To enable cross-account access, you can specify an entire account or IAM entities in another account as the principal in a resource-based policy. For more information, see [Cross account resource access in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html) in the *IAM User Guide*.

## Policy actions for DynamoDB
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**Supports policy actions:** Yes

Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.

The `Action` element of a JSON policy describes the actions that you can use to allow or deny access in a policy. Include actions in a policy to grant permissions to perform the associated operation.



To see a list of DynamoDB actions, see [Actions defined by Amazon DynamoDB](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazondynamodb.html#amazondynamodb-actions-as-permissions) in the *Service Authorization Reference*.

Policy actions in DynamoDB use the following prefix before the action:

```
aws
```

To specify multiple actions in a single statement, separate them with commas.

```
"Action": [
      "aws:action1",
      "aws:action2"
         ]
```





To view examples of DynamoDB identity-based policies, see [Identity-based policy examples for Amazon DynamoDB](security_iam_id-based-policy-examples.md).

## Policy resources for DynamoDB
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**Supports policy resources:** Yes

Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.

The `Resource` JSON policy element specifies the object or objects to which the action applies. As a best practice, specify a resource using its [Amazon Resource Name (ARN)](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference-arns.html). For actions that don't support resource-level permissions, use a wildcard (\$1) to indicate that the statement applies to all resources.

```
"Resource": "*"
```

To see a list of DynamoDB resource types and their ARNs, see [Resources defined by Amazon DynamoDB](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazondynamodb.html#amazondynamodb-resources-for-iam-policies) in the *Service Authorization Reference*. To learn with which actions you can specify the ARN of each resource, see [Actions defined by Amazon DynamoDB](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazondynamodb.html#amazondynamodb-actions-as-permissions).





To view examples of DynamoDB identity-based policies, see [Identity-based policy examples for Amazon DynamoDB](security_iam_id-based-policy-examples.md).

## Policy condition keys for DynamoDB
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**Supports service-specific policy condition keys:** Yes

Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.

The `Condition` element specifies when statements execute based on defined criteria. You can create conditional expressions that use [condition operators](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition_operators.html), such as equals or less than, to match the condition in the policy with values in the request. To see all AWS global condition keys, see [AWS global condition context keys](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_condition-keys.html) in the *IAM User Guide*.

To see a list of DynamoDB condition keys, see [Condition keys for Amazon DynamoDB](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazondynamodb.html#amazondynamodb-policy-keys) in the *Service Authorization Reference*. To learn with which actions and resources you can use a condition key, see [Actions defined by Amazon DynamoDB](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazondynamodb.html#amazondynamodb-actions-as-permissions).

To view examples of DynamoDB identity-based policies, see [Identity-based policy examples for Amazon DynamoDB](security_iam_id-based-policy-examples.md).

## Access control lists (ACLs) in DynamoDB
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**Supports ACLs:** No 

Access control lists (ACLs) control which principals (account members, users, or roles) have permissions to access a resource. ACLs are similar to resource-based policies, although they do not use the JSON policy document format.

## Attribute-based access control (ABAC) with DynamoDB
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**Supports ABAC (tags in policies):** Yes

Attribute-based access control (ABAC) is an authorization strategy that defines permissions based on attributes called tags. You can attach tags to IAM entities and AWS resources, then design ABAC policies to allow operations when the principal's tag matches the tag on the resource.

To control access based on tags, you provide tag information in the [condition element](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition.html) of a policy using the `aws:ResourceTag/key-name`, `aws:RequestTag/key-name`, or `aws:TagKeys` condition keys.

If a service supports all three condition keys for every resource type, then the value is **Yes** for the service. If a service supports all three condition keys for only some resource types, then the value is **Partial**.

For more information about ABAC, see [Define permissions with ABAC authorization](https://docs.aws.amazon.com/IAM/latest/UserGuide/introduction_attribute-based-access-control.html) in the *IAM User Guide*. To view a tutorial with steps for setting up ABAC, see [Use attribute-based access control (ABAC)](https://docs.aws.amazon.com/IAM/latest/UserGuide/tutorial_attribute-based-access-control.html) in the *IAM User Guide*.

## Using Temporary credentials with DynamoDB
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**Supports temporary credentials:** Yes

Temporary credentials provide short-term access to AWS resources and are automatically created when you use federation or switch roles. AWS recommends that you dynamically generate temporary credentials instead of using long-term access keys. For more information, see [Temporary security credentials in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html) and [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.

## Cross-service principal permissions for DynamoDB
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**Supports forward access sessions (FAS):** Yes

 Forward access sessions (FAS) use the permissions of the principal calling an AWS service, combined with the requesting AWS service to make requests to downstream services. For policy details when making FAS requests, see [Forward access sessions](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_forward_access_sessions.html). 

## Service roles for DynamoDB
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**Supports service roles:** Yes

 A service role is an [IAM role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html) that a service assumes to perform actions on your behalf. An IAM administrator can create, modify, and delete a service role from within IAM. For more information, see [Create 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*. 

**Warning**  
Changing the permissions for a service role might break DynamoDB functionality. Edit service roles only when DynamoDB provides guidance to do so.

## Service-linked roles for DynamoDB
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**Supports service-linked roles:** Yes

 A service-linked role is a type of service role that is linked to an AWS service. The service can assume the role to perform an action on your behalf. Service-linked roles appear in your AWS account and are owned by the service. An IAM administrator can view, but not edit the permissions for service-linked roles. 

For details about creating or managing service-linked roles, see [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html). Find a service in the table that includes a `Yes` in the **Service-linked role** column. Choose the **Yes** link to view the service-linked role documentation for that service.

### Supported service-linked roles in DynamoDB
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The following service-linked roles are supported in DynamoDB.
+ DynamoDB uses the service-linked role **AWSServiceRoleForDynamoDBReplication** for global tables replication across AWS Regions. See [DynamoDB global tables security](globaltables-security.md) for more information about the **AWSServiceRoleForDynamoDBReplication** service-linked role.
+ DynamoDB Accelerator (DAX) uses the service-linked role** AWSServiceRoleForDAX** for configuring and maintaining a DAX cluster. See [Using service-linked IAM roles for DAX](using-service-linked-roles.md) for more information about the **AWSServiceRoleForDAX** service-linked role.

In addition to these DynamoDB service-linked roles, DynamoDB uses the Application Auto Scaling service for automatically managing throughput settings on provisioned capacity mode tables. The Application Auto Scaling service uses the service-linked role** AWSServiceRoleForApplicationAutoScaling\$1DynamoDBTable** to manage throughput settings on DynamoDB tables that have auto scaling enabled. See [Service-linked roles for Application Auto Scaling](https://docs.aws.amazon.com/autoscaling/application/userguide/application-auto-scaling-service-linked-roles.html) for more information.