AWS Identity and Access Management (IAM) works by providing a centralized system for managing access to AWS resources securely. It operates based on the following principles:
1. Authentication:
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User Authentication: When a user or application attempts to access AWS resources, IAM verifies their identity through authentication mechanisms such as username/password combinations, access keys, or temporary security credentials.
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Federation: IAM supports identity federation, allowing users to authenticate using credentials from external identity providers like Active Directory, LDAP, or SAML 2.0-compliant systems.
2. Authorization:
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Access Control: After authentication, IAM determines whether the authenticated entity (user, application, or service) is authorized to perform the requested actions on AWS resources.
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Permissions: Permissions are defined using policies, which specify what actions are allowed or denied on which AWS resources. IAM policies can be attached to users, groups, roles, or directly to AWS resources.
3. Entities:
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Users: IAM users represent individuals within your organization who need access to AWS resources. Each user has a unique set of security credentials and can be assigned specific permissions.
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Groups: Groups are collections of IAM users. Permissions can be assigned to groups, allowing you to manage access for multiple users with similar roles more efficiently.
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Roles: IAM roles are sets of permissions that you can assign to entities within or outside of your AWS account. Roles are useful for granting temporary access or enabling applications to access AWS resources securely.
4. Policies:
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JSON Documents: IAM policies are JSON documents that define permissions. They specify the actions allowed or denied and the resources to which the permissions apply.
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Managed Policies: AWS provides managed policies that cover common use cases. You can attach these policies directly to users, groups, or roles, simplifying permission management.
5. Logging and Monitoring:
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Audit Trail: IAM logs record user activity and API calls, providing an audit trail for security and compliance purposes.
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CloudTrail Integration: IAM integrates with AWS CloudTrail, which captures API activity across your AWS infrastructure, including IAM actions.
6. Least Privilege:
- Principle of Least Privilege: IAM encourages the principle of least privilege, which means granting users only the permissions they need to perform their tasks. This minimizes the risk of unauthorized access or accidental misuse of resources.
Example Workflow:
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User Authentication: A user attempts to access an AWS resource, such as an S3 bucket.
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Identity Verification: IAM verifies the user's identity using authentication mechanisms like username/password or access keys.
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Authorization Check: IAM checks whether the user is authorized to perform the requested action (e.g., read, write, delete) on the specified S3 bucket.
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Permission Evaluation: IAM evaluates the permissions associated with the user, including policies attached to the user, group memberships, and any applicable roles.
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Access Granted or Denied: Based on the permission evaluation, IAM either allows or denies the user's access to the S3 bucket.
By following these steps, IAM ensures secure access management to AWS resources, helping organizations enforce security policies, maintain compliance, and protect their data.
