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  • IAM is universal service and it does not apply to a single region; it is cross-region.
  • The root account is the account created for the first time and it has full access (also called as God mode 🧚 ).
  • New users have no permissions when created
  • Access key id and secret access key are required for programmatic access to AWS. They can’t be used to login to the console.
  • Use MFA in the root account. We can use the Google Auth app for this 📱
  • IAM is concerned with the raw AWS resources, not access to running web applications.


Setting up a cross-account IAM role is currently the only method that will allow IAM users to access cross-account S3 buckets both programmatically and via the AWS console.

IAM User

An IAM user is an identity that you create in AWS. It represents the person or application that interacts with AWS services and resources. It consists of a name and credentials.

By default, when you create a new IAM user in AWS, it has no permissions associated with it. To allow the IAM user to perform specific actions in AWS, such as launching an Amazon EC2 instance or creating an Amazon S3 bucket, you must grant the IAM user the necessary permissions.

IAM Policy

An IAM policy is a document that allows or denies permissions to AWS services and resources.

IAM Group

An IAM group is a collection of IAM users. When you assign an IAM policy to a group, all users in the group are granted permissions specified by the policy.

IAM role

An IAM role is an identity that you can assume to gain temporary access to permissions.

Best Practice

IAM roles are ideal for situations in which access to services or resources needs to be granted temporarily, instead of long-term.

Types of policies in IAM

There are four types of policies in IAM:-

  • Identity-based
  • Resource-based
  • Organization SCPs
  • Access control lists (ACLs)

You can provide console access and programmatic access via IAM. Programmatic access includes API and CLI access.


  • IAM is not the managed service for handling MFA Delete setup on S3 buckets
  • Users, groups, roles, permissions, and similar constructs are part of IAM
  • Organizations and organizational units are part of AWS Organizations, a different facility.
  • User policies are not part of IAM but permissions are.
  • IAM policies are written in JSON.
  • IAM policies can be attached to users, groups, and roles in the case of identity-based policies, and AWS services and components via resource-based policies.
  • Restoring revoked permissions for a user and changing the support options need the root user access.
  • IAM changes apply immediately to all users across the system; there is no lag, and no need to log out and back in.
  • Power-user access is a predefined policy that allows access to all AWS services with the exception of group or user management within IAM


  • AWS strongly recommends you delete your root user access keys and create IAM users for everyday use.
  • IAM root user account is needed for very privileged access; in this case, that’s creating a CloudFront key pair, which essentially provides signed access to applications and is a very trusted action.
  • AWS firmly believes that root account access should be highly limited, but also not confined to a single user. Having a very small group of engineers (ideally AWS certified) is the best approach to reducing root account level access as much as possible.
  • You will always need to provide non-root sign-in URLs for new users.
  • New users have no access to AWS services. They are “bare” or “empty” or “naked” users, as they can merely login to the AWS console (if a URL is provided). They cannot make any changes to AWS services or even view services.
  • AWS usernames have to be unique across the AWS account in which that user exists 🔑
  • If you have an external Active Directory, you’d want to federate those users into AWS. This allows you to use the existing user base, not re-create each individual user.

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