AWS VPC

Design and manage Virtual Private Cloud networking for production AWS environments with proper subnet isolation, routing, and security.

When to Use This Skill

• Building a new VPC for production, staging, or development
• Setting up public/private subnet architecture across multiple AZs
• Configuring NAT Gateways for private subnet internet access
• Creating security groups and NACLs for network segmentation
• Setting up VPC peering or Transit Gateway for multi-VPC connectivity
• Implementing VPC endpoints for private access to AWS services
• Troubleshooting connectivity issues between resources

Prerequisites

• AWS CLI v2 installed and configured
• IAM permissions: ec2:* (or scoped to VPC-related actions)
• CIDR range planning completed (avoid overlaps with on-premises or other VPCs)
• For VPC peering: access to both VPCs (same or different accounts)

Network Architecture

VPC (10.0.0.0/16) - 65,536 IPs
├── Public Subnets (internet-facing via IGW)
│   ├── 10.0.1.0/24 (us-east-1a) - 256 IPs - ALBs, NAT GW, bastion
│   ├── 10.0.2.0/24 (us-east-1b) - 256 IPs
│   └── 10.0.3.0/24 (us-east-1c) - 256 IPs
├── Private Subnets (app tier, NAT GW for outbound)
│   ├── 10.0.11.0/24 (us-east-1a) - 256 IPs - ECS, EC2, Lambda
│   ├── 10.0.12.0/24 (us-east-1b) - 256 IPs
│   └── 10.0.13.0/24 (us-east-1c) - 256 IPs
├── Data Subnets (isolated, no internet)
│   ├── 10.0.21.0/24 (us-east-1a) - 256 IPs - RDS, ElastiCache
│   ├── 10.0.22.0/24 (us-east-1b) - 256 IPs
│   └── 10.0.23.0/24 (us-east-1c) - 256 IPs
├── Internet Gateway
├── NAT Gateways (one per AZ for HA)
├── Route Tables (public, private, data)
└── VPC Flow Logs → CloudWatch / S3

Create a VPC with CLI

# Create the VPC
VPC_ID=$(aws ec2 create-vpc \
  --cidr-block 10.0.0.0/16 \
  --tag-specifications 'ResourceType=vpc,Tags=[{Key=Name,Value=production-vpc},{Key=Environment,Value=production}]' \
  --query 'Vpc.VpcId' --output text)

# Enable DNS support and hostnames
aws ec2 modify-vpc-attribute --vpc-id $VPC_ID --enable-dns-support '{"Value":true}'
aws ec2 modify-vpc-attribute --vpc-id $VPC_ID --enable-dns-hostnames '{"Value":true}'

# Create public subnets
PUB_SUB_A=$(aws ec2 create-subnet \
  --vpc-id $VPC_ID \
  --cidr-block 10.0.1.0/24 \
  --availability-zone us-east-1a \
  --tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=public-a},{Key=Tier,Value=public}]' \
  --query 'Subnet.SubnetId' --output text)

PUB_SUB_B=$(aws ec2 create-subnet \
  --vpc-id $VPC_ID \
  --cidr-block 10.0.2.0/24 \
  --availability-zone us-east-1b \
  --tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=public-b},{Key=Tier,Value=public}]' \
  --query 'Subnet.SubnetId' --output text)

# Enable auto-assign public IP on public subnets
aws ec2 modify-subnet-attribute --subnet-id $PUB_SUB_A --map-public-ip-on-launch
aws ec2 modify-subnet-attribute --subnet-id $PUB_SUB_B --map-public-ip-on-launch

# Create private subnets
PRIV_SUB_A=$(aws ec2 create-subnet \
  --vpc-id $VPC_ID \
  --cidr-block 10.0.11.0/24 \
  --availability-zone us-east-1a \
  --tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=private-a},{Key=Tier,Value=private}]' \
  --query 'Subnet.SubnetId' --output text)

PRIV_SUB_B=$(aws ec2 create-subnet \
  --vpc-id $VPC_ID \
  --cidr-block 10.0.12.0/24 \
  --availability-zone us-east-1b \
  --tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=private-b},{Key=Tier,Value=private}]' \
  --query 'Subnet.SubnetId' --output text)

# Create data subnets (isolated)
DATA_SUB_A=$(aws ec2 create-subnet \
  --vpc-id $VPC_ID \
  --cidr-block 10.0.21.0/24 \
  --availability-zone us-east-1a \
  --tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=data-a},{Key=Tier,Value=data}]' \
  --query 'Subnet.SubnetId' --output text)

DATA_SUB_B=$(aws ec2 create-subnet \
  --vpc-id $VPC_ID \
  --cidr-block 10.0.22.0/24 \
  --availability-zone us-east-1b \
  --tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=data-b},{Key=Tier,Value=data}]' \
  --query 'Subnet.SubnetId' --output text)

Internet Gateway and NAT Gateway

# Create and attach Internet Gateway
IGW_ID=$(aws ec2 create-internet-gateway \
  --tag-specifications 'ResourceType=internet-gateway,Tags=[{Key=Name,Value=production-igw}]' \
  --query 'InternetGateway.InternetGatewayId' --output text)
aws ec2 attach-internet-gateway --vpc-id $VPC_ID --internet-gateway-id $IGW_ID

# Create public route table
PUB_RT=$(aws ec2 create-route-table \

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