AWS CloudTrail
用户指南 (版本 1.0)
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适用于 AWS CloudTrail 的 Identity and Access Management

AWS Identity and Access Management (IAM) is an AWS service that helps an administrator securely control access to AWS resources. IAM administrators control who can be authenticated (signed in) and authorized (have permissions) to use CloudTrail resources. IAM is an AWS service that you can use with no additional charge.

受众

How you use AWS Identity and Access Management (IAM) differs, depending on the work you do in CloudTrail.

Service user – If you use the CloudTrail service to do your job, then your administrator provides you with the credentials and permissions that you need. As you use more CloudTrail features to do your work, you might need additional permissions. Understanding how access is managed can help you request the right permissions from your administrator. If you cannot access a feature in CloudTrail, see 故障排除 AWS CloudTrail 身份和访问.

Service administrator – If you're in charge of CloudTrail resources at your company, you probably have full access to CloudTrail. It's your job to determine which CloudTrail features and resources your employees should access. You must then submit requests to your IAM administrator to change the permissions of your service users. Review the information on this page to understand the basic concepts of IAM. To learn more about how your company can use IAM with CloudTrail, see AWS CloudTrail 如何与 IAM 协同工作.

IAM administrator – If you're an IAM administrator, you might want to learn details about how you can write policies to manage access to CloudTrail. To view example CloudTrail identity-based policies that you can use in IAM, see AWS CloudTrail 基于身份的策略示例.

使用身份进行身份验证

Authentication is how you sign in to AWS using your identity credentials. For more information about signing in using the AWS 管理控制台, see The IAM Console and Sign-in Page in the IAM 用户指南.

You must be authenticated (signed in to AWS) as the AWS 账户根用户, an IAM user, or by assuming an IAM role. You can also use your company's single sign-on authentication, or even sign in using Google or Facebook. In these cases, your administrator previously set up identity federation using IAM roles. When you access AWS using credentials from another company, you are assuming a role indirectly.

To sign in directly to the AWS 管理控制台, use your password with your 根用户 email or your IAM user name. You can access AWS programmatically using your 根用户 or IAM user access keys. AWS provides SDK and command line tools to cryptographically sign your request using your credentials. If you don’t use AWS tools, you must sign the request yourself. Do this using 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.

Regardless of the authentication method that you use, you might also be required to provide additional security information. For example, AWS recommends that you use multi-factor authentication (MFA) to increase the security of your account. To learn more, see Using Multi-Factor Authentication (MFA) in AWS in the IAM 用户指南.

AWS 账户根用户

当您首次创建 AWS 账户时,最初使用的是一个对账户中所有 AWS 服务和资源有完全访问权限的单点登录身份。此身份称为 账户 AWS,可使用您创建账户时所用的电子邮件地址和密码登录来获得此身份。强烈建议您不使用 根用户 执行日常任务,即使是管理任务。请遵守仅将用于创建首个 用户的最佳实践。然后请妥善保存 根用户 凭证,仅用它们执行少数账户和服务管理任务。

IAM 用户和群组

An IAM user is an identity within your AWS account that has specific permissions for a single person or application. An IAM user can have long-term credentials such as a user name and password or a set of access keys. To learn how to generate access keys, see Managing Access Keys for IAM Users in the IAM 用户指南. When you generate access keys for an IAM user, make sure you view and securely save the key pair. You cannot recover the secret access key in the future. Instead, you must generate a new access key pair.

An IAM group is an identity that specifies a collection of IAM users. You can't sign in as a group. You can use groups to specify permissions for multiple users at a time. Groups make permissions easier to manage for large sets of users. For example, you could have a group named IAMAdmins and give that group permissions to administer IAM resources.

Users are different from roles. A user is uniquely associated with one person or application, but a role is intended to be assumable by anyone who needs it. Users have permanent long-term credentials, but roles provide temporary credentials. To learn more, see When to Create an IAM User (Instead of a Role) in the IAM 用户指南.

IAM 角色

An IAM role is an identity within your AWS account that has specific permissions. It is similar to an IAM user, but is not associated with a specific person. You can temporarily assume an IAM role in the AWS 管理控制台 by switching roles. You can assume a role by calling an AWS CLI or AWS API operation or by using a custom URL. For more information about methods for using roles, see Using IAM Roles in the IAM 用户指南.

IAM roles with temporary credentials are useful in the following situations:

  • Temporary IAM user permissions – An IAM user can assume an IAM role to temporarily take on different permissions for a specific task.

  • Federated user access – 您也可以不创建 IAM 用户,而是使用来自 AWS Directory Service、您的企业用户目录或 Web 身份提供商的既有用户身份。他们被称为联合身份用户。在通过身份提供商请求访问权限时,AWS 将为联合用户分配角色。有关联合身份用户的更多信息,请参阅 IAM 用户指南 中的联合身份用户和角色

  • Cross-account access – You can use an IAM role to allow someone (a trusted principal) in a different account to access resources in your account. Roles are the primary way to grant cross-account access. However, with some AWS services, you can attach a policy directly to a resource (instead of using a role as a proxy). To learn the difference between roles and resource-based policies for cross-account access, see How IAM Roles Differ from Resource-based Policies in the IAM 用户指南.

  • AWS service access –您可以使用您的账户中的 IAM 角色向 AWS 服务授予对您账户中资源的访问权限。例如,您可以创建一个角色,此角色允许 Amazon Redshift 代表您访问 Amazon S3 存储桶,然后将该存储桶提供的数据加载到 Amazon Redshift 群集中。有关更多信息,请参阅 IAM 用户指南 中的创建向 AWS 服务委派权限的角色

  • Applications running on Amazon EC2 –对于在 EC2 实例上运行、并发出 AWS API 请求的应用程序,您可以使用 IAM 角色管理它们的临时凭证。这优先于在 EC2 实例中存储访问密钥。要将 AWS 角色分配给 EC2 实例并使其对该实例的所有应用程序可用,您可以创建一个附加到实例的实例配置文件。实例配置文件包含角色,并使 EC2 实例上运行的程序能够获得临时凭证。有关更多信息,请参阅 IAM 用户指南中的使用 IAM 角色向在 Amazon EC2 实例上运行的应用程序授予权限

To learn whether to use IAM roles, see When to Create an IAM Role (Instead of a User) in the IAM 用户指南.

使用策略管理访问

You control access in AWS by creating policies and attaching them to IAM identities or AWS resources. A policy is an object in AWS that, when associated with an identity or resource, defines their permissions. AWS evaluates these policies when an entity (根用户, IAM user, or IAM role) makes a request. Permissions in the policies determine whether the request is allowed or denied. Most policies are stored in AWS as JSON documents. For more information about the structure and contents of JSON policy documents, see Overview of JSON Policies in the IAM 用户指南.

An IAM administrator can use policies to specify who has access to AWS resources, and what actions they can perform on those resources. Every IAM entity (user or role) starts with no permissions. In other words, by default, users can do nothing, not even change their own password. To give a user permission to do something, an administrator must attach a permissions policy to a user. Or the administrator can add the user to a group that has the intended permissions. When an administrator gives permissions to a group, all users in that group are granted those permissions.

IAM policies define permissions for an action regardless of the method that you use to perform the operation. For example, suppose that you have a policy that allows the iam:GetRole action. A user with that policy can get role information from the AWS 管理控制台, the AWS CLI, or the AWS API.

基于身份的策略

Identity-based policies are JSON permissions policy documents that you can attach to an identity, such as an IAM user, role, or group. These policies control what actions that identity can perform, on which resources, and under what conditions. To learn how to create an identity-based policy, see Creating IAM Policies in the IAM 用户指南.

Identity-based policies can be further categorized as inline policies or managed policies. Inline policies are embedded directly into a single user, group, or role. Managed policies are standalone policies that you can attach to multiple users, groups, and roles in your AWS account. Managed policies include AWS managed policies and customer managed policies. To learn how to choose between a managed policy or an inline policy, see Choosing Between Managed Policies and Inline Policies in the IAM 用户指南.

基于资源的策略

Resource-based policies are JSON policy documents that you attach to a resource such as an Amazon S3 bucket. Service administrators can use these policies to define what actions a specified principal (account member, user, or role) can perform on that resource and under what conditions. Resource-based policies are inline policies. There are no managed resource-based policies.

访问控制列表 (ACL)

Access control policies (ACLs) control which principals (account members, users, or roles) have permissions to access a resource. ACLs are similar to resource-based policies, although they are the only policy type that does not use the JSON policy document format. Amazon S3, AWS WAF, and Amazon VPC are examples of services that support ACLs. To learn more about ACLs, see Access Control List (ACL) Overview in the Amazon Simple Storage Service Developer Guide.

其他策略类型

AWS supports additional, less-common policy types. These policy types can set the maximum permissions granted to you by the more common policy types.

  • Permissions boundaries – A permissions boundary is an advanced feature in which you set the maximum permissions that an identity-based policy can grant to an IAM entity (IAM user or role). You can set a permissions boundary for an entity. The resulting permissions are the intersection of entity's identity-based policies and its permissions boundaries. Resource-based policies that specify the user or role in the Principal field are not limited by the permissions boundary. An explicit deny in any of these policies overrides the allow. For more information about permissions boundaries, see Permissions Boundaries for IAM Entities in the IAM 用户指南.

  • Service control policies (SCPs) – SCPs are JSON policies that specify the maximum permissions for an organization or organizational unit (OU) in AWS Organizations. AWS Organizations is a service for grouping and centrally managing multiple AWS accounts that your business owns. If you enable all features in an organization, then you can apply service control policies (SCPs) to any or all of your accounts. The SCP limits permissions for entities in member accounts, including each AWS 账户根用户. For more information about 组织 and SCPs, see How SCPs Work in the AWS Organizations 用户指南.

  • Session policies – Session policies are advanced policies that you pass as a parameter when you programmatically create a temporary session for a role or federated user. The resulting session's permissions are the intersection of the user or role's identity-based policies and the session policies. Permissions can also come from a resource-based policy. An explicit deny in any of these policies overrides the allow. For more information, see Session Policies in the IAM 用户指南.

多个策略类型

When multiple types of policies apply to a request, the resulting permissions are more complicated to understand. To learn how AWS determines whether to allow a request when multiple policy types are involved, see Policy Evaluation Logic in the IAM 用户指南.