Cloud Networking Cheatsheet

VPC & Subnets

# AWS
aws ec2 create-vpc --cidr-block 10.0.0.0/16
aws ec2 create-subnet --vpc-id vpc-abc \
  --cidr-block 10.0.1.0/24 --availability-zone us-east-1a

# GCP (custom mode)
gcloud compute networks create prod-vpc --subnet-mode=custom
gcloud compute networks subnets create web-subnet \
  --network=prod-vpc --range=10.10.0.0/24 --region=us-central1

CIDR Quick Sizes

Routing & NAT

# Internet gateway + default route (public)
aws ec2 attach-internet-gateway --vpc-id vpc-abc --internet-gateway-id igw-1
aws ec2 create-route --route-table-id rtb-pub \
  --destination-cidr-block 0.0.0.0/0 --gateway-id igw-1

# NAT for private egress
aws ec2 create-route --route-table-id rtb-priv \
  --destination-cidr-block 0.0.0.0/0 --nat-gateway-id nat-1

Firewall

# AWS security group ingress
aws ec2 authorize-security-group-ingress --group-id sg-1 \
  --protocol tcp --port 443 --cidr 0.0.0.0/0

# GCP firewall rule
gcloud compute firewall-rules create allow-https \
  --network=prod-vpc --allow=tcp:443 --source-ranges=0.0.0.0/0

SG vs NACL

Load Balancing

# GCP health check
gcloud compute health-checks create http hc-web \
  --port=80 --request-path=/healthz \
  --check-interval=5s --unhealthy-threshold=3

Connectivity

# GCP peering (create on both sides)
gcloud compute networks peerings create a-to-b \
  --network=vpc-a --peer-network=vpc-b

Cross-Cloud Map