Why VPC provides network isolation in AWS - See It in Action

Why VPC Provides Network Isolation

📖 Scenario: You are setting up a cloud environment for a small company. You want to keep their network safe and separate from other users in the cloud.

🎯 Goal: Build a simple Virtual Private Cloud (VPC) configuration that shows how network isolation is created using subnets and security groups.

📋 What You'll Learn

Create a VPC with a specific CIDR block

Add two subnets inside the VPC

Create a security group that allows only specific traffic

Associate the security group with an instance inside the VPC

💡 Why This Matters

🌍 Real World

Companies use VPCs to keep their cloud resources private and secure, separating them from other users and controlling network traffic.

💼 Career

Understanding VPCs and network isolation is essential for cloud architects and engineers to design secure cloud environments.

1

Create a VPC with CIDR block

Create a VPC named MyVPC with the CIDR block 10.0.0.0/16.

AWS

# Create a VPC named MyVPC with CIDR block 10.0.0.0/16
# Your code here

Need a hint?

Use the aws_vpc resource and set cidr_block to 10.0.0.0/16.

2

Add two subnets inside the VPC

Add two subnets named SubnetA and SubnetB inside MyVPC with CIDR blocks 10.0.1.0/24 and 10.0.2.0/24 respectively.

AWS

resource "aws_vpc" "MyVPC" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "MyVPC"
  }
}

# Add two subnets SubnetA and SubnetB inside MyVPC
# Your code here

Need a hint?

Use aws_subnet resources and link them to MyVPC using vpc_id.

3

Create a security group to allow specific traffic

Create a security group named MySG inside MyVPC that allows inbound TCP traffic on port 22 (SSH) from anywhere.

AWS

resource "aws_vpc" "MyVPC" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "MyVPC"
  }
}

resource "aws_subnet" "SubnetA" {
  vpc_id     = aws_vpc.MyVPC.id
  cidr_block = "10.0.1.0/24"
  tags = {
    Name = "SubnetA"
  }
}

resource "aws_subnet" "SubnetB" {
  vpc_id     = aws_vpc.MyVPC.id
  cidr_block = "10.0.2.0/24"
  tags = {
    Name = "SubnetB"
  }
}

# Create a security group MySG inside MyVPC allowing inbound TCP port 22 from 0.0.0.0/0
# Your code here

Need a hint?

Use aws_security_group with ingress rules for port 22 TCP.

4

Associate the security group with an instance inside the VPC

Create an EC2 instance named MyInstance in SubnetA and associate it with the security group MySG.

AWS

resource "aws_vpc" "MyVPC" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "MyVPC"
  }
}

resource "aws_subnet" "SubnetA" {
  vpc_id     = aws_vpc.MyVPC.id
  cidr_block = "10.0.1.0/24"
  tags = {
    Name = "SubnetA"
  }
}

resource "aws_subnet" "SubnetB" {
  vpc_id     = aws_vpc.MyVPC.id
  cidr_block = "10.0.2.0/24"
  tags = {
    Name = "SubnetB"
  }
}

resource "aws_security_group" "MySG" {
  name        = "MySG"
  description = "Allow SSH inbound"
  vpc_id      = aws_vpc.MyVPC.id

  ingress {
    description      = "SSH from anywhere"
    from_port        = 22
    to_port          = 22
    protocol         = "tcp"
    cidr_blocks      = ["0.0.0.0/0"]
  }

  egress {
    from_port        = 0
    to_port          = 0
    protocol         = "-1"
    cidr_blocks      = ["0.0.0.0/0"]
  }

  tags = {
    Name = "MySG"
  }
}

# Create an EC2 instance MyInstance in SubnetA with security group MySG
# Your code here

Need a hint?

Use aws_instance resource with subnet_id and vpc_security_group_ids set correctly.