By Tahir Riaz
Introduction
IAM in AWS (Identity and Access Management) is a foundational service that controls who can access your AWS resources and how. It’s essential for maintaining a secure and efficient cloud environment. Whether you’re creating users, managing permissions, or enabling secure access for applications, IAM is the backbone of access control in AWS.
Key IAM in AWS Concepts and Features
Understanding Identities in IAM
IAM manages several identity types:
- Username – An identifiable login name.
- Access ID – Used for programmatic access.
- ARN – A unique identifier for AWS resources.
- Principal – An entity (like a user, role, or app) performing actions on AWS.
These identities are the foundation of access control in IAM.
Requests, Context, and Authorization in IAM
Every time a principal interacts with AWS, a request is generated. This request includes:
- Actions: Reading or modifying a resource
- Environment Data: IP, region, user agent
- Resource Data: Metadata of the AWS resource
AWS evaluates this request using IAM policies to determine access.
IAM Users, Groups, and Federated Access
IAM Users
Avoid using the root user. Instead, create individual IAM users, each with their own credentials and tailored permissions.
IAM Groups
Groups make it easier to manage multiple users.
- Users can belong to multiple groups.
- Groups can’t contain other groups or have their own credentials.
Groups are ideal for assigning bulk permissions.
Federated Users
You can also allow access via third-party identities like Google or SAML, without creating separate IAM accounts.I
IAM Roles and Policies in AWS
IAM Roles
Roles are identities without permanent credentials. They are assumed temporarily by trusted users or AWS services.
Example: An EC2 instance assumes a role to access an S3 bucket.
Instance Profiles
These allow EC2 instances to assume roles, enabling secure app access to AWS resources.
IAM Policies
Policies define who can do what on which resources.
Types include:
- Managed policies (maintained by AWS)
- Inline policies (custom for one identity)
- Resource-based policies
- Trust policies
Working with AWS STS (Security Token Service)
AWS STS provides temporary credentials for secure, time-limited access.
Key APIs:
AssumeRoleAssumeRoleWithSAMLAssumeRoleWithWebIdentityGetFederationTokenGetSessionToken
STS is ideal for federated access and mobile/web apps needing temporary AWS credentials.
Using IAM Access Analyzer for Policy Validation
IAM Access Analyzer helps detect overly permissive access and validates IAM policies.
It supports services like:
- S3
- Lambda
- IAM
- KMS
This makes it a valuable auditing and security tool in your AWS environment.
Best Practices for Managing IAM in AWS
- Never use the root account; create an admin IAM user instead
- Enable MFA for all users
- Use IAM groups to manage permissions
- Rotate access keys and passwords regularly
- Implement least-privilege access
- Use roles for applications needing AWS access
- Monitor activity with CloudTrail and Access Analyzer
- Apply conditional access (IP address, time-based, etc.)
- Use managed policies when possible
- Regularly audit and clean up permissions
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