Introduction

AWS Identity and Access Management (IAM) is a critical security service that controls who can access what in AWS. Whether you’re an administrator, developer, or security engineer, mastering IAM is essential for ensuring secure access to AWS resources.

In this article, we will cover IAM fundamentals, best practices, hands-on labs, and real-world examples to solidify your understanding

Objective

• Understand IAM fundamentals and set up users, groups, and policies.
• Implement IAM best practices for security.

Topics to Cover

–What is AWS IAM?

IAM Concepts: Users, Groups, Roles, and Policies

-IAM Policies:

Managed Policies vs. Inline Policies

JSON Policy Structure (Effect, Action, Resource, Condition)

-IAM Best Practices:

Principle of Least Privilege

Avoid Root User for Daily Operations

Step 1: Read IAM Documentation

Before jumping into practical implementation, it’s essential to go through the AWS IAM Documentation. This will help you understand core concepts like Users, Groups, Roles, and Policies and how they interact within AWS.

Step 2: Hands-on Labs (Practical)

💻 Set Up IAM Users & Groups

Log in to AWS Console

Navigate to IAM Service

1️⃣ Create Two Groups

• AdminGroup (Full access)
• DeveloperGroup (Limited access)

2️⃣ Create Users & Assign Them to Groups

• admin-user → Assigned to AdminGroup
• dev-user → Assigned to DeveloperGroup

3️⃣ Attach IAM Policies

• AdminGroup → Attach AdministratorAccess
• DeveloperGroup → Attach PowerUserAccess

4️⃣ Create a Custom IAM Policy

Attach it to DeveloperGroup.

Write a JSON policy to allow S3 read-only access.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::your-bucket-name/*"
    }
  ]
}

Step 3: Validation & Testing

✅ Log in with Each User

• Use admin-user and dev-user credentials to log in separately.

✅ Verify Permissions

• admin-user should have full access.
• dev-user should have restricted permissions.

✅ Try Accessing S3 with dev-user

• It should allow read access but deny write operations.

Step 4: What I Learned

🔹 Key Takeaways

1. IAM is AWS’s security layer for managing access control.
2. IAM consists of Users, Groups, Roles, and Policies.
3. Policies define permissions using JSON-based rules.
4. Best Practices:
   • Use Least Privilege principle.
   • Never use the root user for daily tasks.
   • Use IAM roles for applications instead of hardcoding credentials.

🔹 Challenges & How I Solved Them

❌ Challenge 1: Understanding IAM Policies (Managed vs. Inline)

• Solution: Managed Policies are reusable and can be attached to multiple users/groups, while Inline Policies are embedded within a single user or group. Best practice: Use Managed Policies.

❌ Challenge 2: Testing Permissions Effectively

• Solution: Used IAM Policy Simulator to validate policies before applying them.

❌ Challenge 3: Writing a Custom JSON Policy

• Solution: Used the AWS Policy Generator and adjusted the JSON structure based on AWS documentation.

Step 5: How IAM Works (Simplified)

1. User logs in (AWS Console, CLI, or API).
2. IAM checks permissions based on attached policies.
3. If permissions allow, the action is executed. If denied, an error occurs.
4. Policy Evaluation Order:
   • Explicit Deny > Explicit Allow > Default Deny (implicit).

🎯 Example IAM Flow in Action

• dev-user tries to delete an S3 object.
• IAM checks DeveloperGroup policy → S3:DeleteObject is not allowed.
• Result: Access is denied.

Final Thoughts & Next Steps

✅ IAM is powerful but complex—understanding policies is crucial. ✅ Hands-on practice is the best way to master IAM security. ✅ Next, explore IAM Roles for EC2 & Lambda to improve security for applications.

By implementing IAM best practices, you ensure a secure AWS environment, reducing risks and enforcing proper access control.