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Amazon Web Services AWS Broken Labs

Lab 03 - VPC Security Group

Difficulty: Intermediate Service: Amazon VPC

Cost: This lab uses a t2.micro instance (Free Tier eligible). If left running outside the Free Tier, the cost is approximately $0.30/day. Delete the stack when you are done.

Scenario

Your team deployed a web server on EC2 in a custom VPC. The CloudFormation stack completed successfully. The instance is running, the Internet Gateway is attached, and the route table has a working default route. But the page still won’t load.

What Was Deployed

Resource Purpose
AWS::EC2::VPC Custom VPC for the lab (10.0.0.0/16)
AWS::EC2::Subnet Subnet with auto-assign public IP enabled
AWS::EC2::InternetGateway Internet Gateway — created and attached to the VPC
AWS::EC2::RouteTable Route table with a 0.0.0.0/0 route to the Internet Gateway
AWS::EC2::SecurityGroup Security group controlling inbound traffic to the instance
AWS::EC2::Instance t2.micro running a web server

The stack deployed without errors. The instance is running and the web server is active.

Deploy the Lab

  1. Open the AWS CloudFormation console
  2. Click Create stack > With new resources (standard)
  3. Select Upload a template file and upload lab-03-sg.yaml
  4. Enter a stack name (e.g., brokenlabs-vpc-lab-03) and click Next > Next > Submit
  5. Wait for the stack status to reach CREATE_COMPLETE (takes 2–3 minutes)
  6. Open the stack Outputs tab — you will see InstanceId, InstancePublicIP, and WebPageURL

The Problem

Open the WebPageURL from the stack Outputs in your browser.

Expected: the AWS Broken Labs welcome page loads. Actual: the browser displays:

This site can't be reached
ERR_CONNECTION_TIMED_OUT

The instance is running and healthy. The Internet Gateway is attached. The route table has a valid default route. The page still never arrives.

Fix the Lab

The routing layer looks correct. Something is filtering inbound traffic before it reaches the web server.

Need help? Open hints.md for progressive hints.

Cleanup

  1. Open CloudFormation, select your stack, and click Delete
  2. Wait for the stack to reach DELETE_COMPLETE (or disappear from the list)
  3. Verify in the EC2 console that the instance no longer appears (or shows Terminated)

Resources