Networking in the Cloud (VPC Intro)

Build a private neighborhood

A virtual private cloud (VPC) or virtual network is your isolated address space in the cloud. You choose CIDR ranges, split them into subnets, and decide which subnets are public (internet-facing) or private.

Route and gate traffic

• Route tables decide where packets go next
• Internet gateways or equivalent allow public subnet traffic to reach the internet
• NAT gateways let private subnets make outbound calls without accepting inbound internet traffic
• Peering and private links connect networks without traversing the public internet

Filter with security controls

Security groups or network security groups act like stateful firewalls on instances or NICs. Network ACLs can filter at the subnet level. Default-deny inbound and open only the ports you need.

Inspect your network skeleton

Listing VPCs or VNets helps you see what already exists in an account.

# AWS
aws ec2 describe-vpcs --query 'Vpcs[].{Id:VpcId,Cidr:CidrBlock}' --output table

# Azure
az network vnet list --output table

# Google Cloud
gcloud compute networks list