Lesson 03 — Google Cloud Networking

Welcome

Networking forms the backbone of every Google Cloud Platform (GCP) environment.

Whether an organisation hosts web applications, Kubernetes clusters, databases, APIs, or AI workloads, every service communicates through Google’s cloud networking infrastructure.

For a Cloud Penetration Tester, understanding Google Cloud networking is critical because network design directly influences:

Attack surface exposure
Resource accessibility
Lateral movement opportunities
Segmentation effectiveness
Remote administration
Internet-facing services
Data protection

This lesson introduces Google Cloud networking from an enterprise and offensive security perspective.

Learning Objectives

After completing this lesson, you will be able to:

Understand Google Cloud networking architecture.
Explain Virtual Private Cloud (VPC).
Understand subnets and regions.
Explain firewall rules.
Understand routes and routing.
Identify common network attack surfaces.
Explain enterprise Google Cloud network design.
Recognise common networking security risks.

Business Scenario

You are working as a Cloud Penetration Tester at CloudNova Technologies.

A global organisation has deployed multiple business applications across Google Cloud using several VPCs connected through shared networking.

Before beginning an enterprise security assessment, your manager asks you to review the customer’s cloud network architecture and identify areas that require further investigation.

Your goal is to understand how the environment is connected before assessing its security posture.

Why Cloud Networking Matters

Cloud resources rarely operate independently.

Virtual Machines

↓

Cloud Storage

↓

Databases

↓

Load Balancers

↓

Kubernetes Clusters

↓

Cloud Functions

↓

Users

All communicate across cloud networks.

If the network is poorly designed or improperly secured, attackers may gain access to resources that were never intended to be publicly accessible.

Google Cloud Virtual Private Cloud (VPC)

A Virtual Private Cloud (VPC) is Google’s virtual networking environment.

A VPC allows organisations to:

Deploy cloud resources.
Isolate workloads.
Control communication.
Define network boundaries.
Secure enterprise applications.

Unlike traditional networks, Google Cloud VPCs are global resources, allowing connectivity across multiple regions while maintaining centralised management.

Subnets

Subnets divide a VPC into smaller logical networks.

Organisations commonly create separate subnets for:

Web Servers
Application Servers
Database Servers
Kubernetes Nodes
Management Systems
Shared Services

Proper subnet design improves isolation and reduces unnecessary communication between workloads.

Firewall Rules

Google Cloud Firewall Rules determine which traffic is allowed or denied.

Rules are based on:

Source
Destination
Protocol
Port
Target resources
Priority

During a security assessment, firewall rules are reviewed to identify:

Unnecessary exposure
Overly permissive access
Missing segmentation
Weak administrative controls

Routes

Routes determine how network traffic travels within Google Cloud.

Common route types include:

System Routes
Custom Routes
Static Routes
Dynamic Routes

A penetration tester should understand routing because it influences communication paths between workloads and affects potential attack paths.

External Connectivity

Enterprise environments often connect Google Cloud to external networks using:

Cloud VPN
Cloud Interconnect
Partner Interconnect
Hybrid Connectivity

These connections enable communication between on-premises infrastructure and Google Cloud resources.

During security reviews, assess whether connectivity follows organisational security policies.

Load Balancers

Google Cloud Load Balancers distribute traffic across multiple resources.

Common types include:

External Load Balancers
Internal Load Balancers
HTTP(S) Load Balancers
TCP Load Balancers
SSL Proxy Load Balancers

Load balancers often represent publicly accessible entry points and should be included in attack surface reviews.

Cloud NAT

Cloud NAT enables private resources to access external services without exposing public IP addresses.

Review:

NAT Gateway configuration
Outbound connectivity
Logging
Network segmentation

Proper NAT implementation reduces unnecessary public exposure.

Private Google Access

Private Google Access allows private cloud resources to communicate with Google-managed services without requiring public IP addresses.

This helps reduce external exposure and supports secure cloud architectures.

Enterprise Network Architecture

Large organisations commonly deploy:

Internet

↓

Cloud Load Balancer

↓

Web Tier

↓

Application Tier

↓

Database Tier

↓

Management Network

↓

Shared Services

↓

Monitoring & Logging

Each layer should be segmented and protected with appropriate network controls.

Common Network Attack Surfaces

During enterprise Google Cloud assessments, common areas of review include:

Public IP addresses
Open firewall rules
Exposed management interfaces
Weak segmentation
Shared VPC configuration
VPN configuration
Load Balancers
Cloud NAT
Kubernetes networking
Hybrid connectivity

These components influence the overall cloud attack surface.

Enterprise Networking Best Practices

Secure Google Cloud environments typically:

Minimise public exposure.
Apply least-privilege firewall rules.
Segment workloads by function.
Protect administrative interfaces.
Use private networking where possible.
Enable logging for network events.
Review firewall rules regularly.
Monitor network traffic continuously.

Enterprise Skills You Will Develop

By completing this lesson you will learn how to:

Understand Google Cloud networking architecture.
Review enterprise VPC design.
Assess firewall rules.
Identify exposed resources.
Review routing and connectivity.
Evaluate cloud network security.
Prepare for enterprise network security assessments.

Key Takeaways

After completing this lesson you should understand:

Google Cloud VPC architecture.
Subnets.
Firewall Rules.
Routes.
Cloud NAT.
Load Balancers.
Private Google Access.
Enterprise network architecture.
Common cloud networking attack surfaces.

Knowledge Check

You should now be able to answer:

What is a Google Cloud VPC?
Why are subnets important?
How do firewall rules improve cloud security?
What is Cloud NAT?
Why are load balancers included in penetration testing engagements?
What are common enterprise network attack surfaces?

Next Lesson

➡️ Lesson 04 — Compute Engine Security

In the next lesson, you will learn how to assess Google Compute Engine virtual machines, operating system configurations, identity integration, storage, metadata services, and enterprise compute security from a Cloud Penetration Tester’s perspective.