Private Service Connect and VPC Service Controls — Complementary OR Mutually Exclusive?

Introduction

In the ever-evolving landscape of cloud computing, securing your resources and data is paramount. Google Cloud Platform (GCP) offers a robust suite of networking and security services designed to help organizations build secure and compliant cloud environments. Among these, Private Service Connect (PSC) and VPC Service Controls (VPC SC) stand out as powerful tools for enhancing network security and data protection. While both aim to improve the security posture of your GCP deployments, they address different aspects of network isolation and data exfiltration prevention. This blog post will explore the functionalities, use cases, and key differences between Private Service Connect and VPC Service Controls, providing a comprehensive guide to help you understand when and how to effectively leverage each service.

Private Service Connect (PSC)

Private Service Connect is a networking capability within Google Cloud that enables private consumption of managed services. It allows service consumers to access managed services privately from within their Virtual Private Cloud (VPC) network, and conversely, allows managed service producers to host these services in their own separate VPC networks while offering a private connection to their consumers. This means that traffic between consumers and producers remains entirely within Google Cloud’s network, never traversing the public internet.

Key Features of Private Service Connect

• Private Connectivity: PSC ensures that all traffic between your VPC network and managed services (Google-published, third-party, or intra-organization) remains private, using internal IP addresses. This eliminates the need for public IP addresses and NAT gateways, reducing exposure to internet-based threats.
• Service-Oriented Design: PSC leverages a service-oriented approach where producer services are published through load balancers that expose a single IP address to the consumer VPC network. This provides granular control, as consumer traffic can only access the service IP address, not the entire peered VPC network.
• Explicit Authorization: PSC incorporates an authorization model that grants consumers and producers granular control over connections. This ensures that only intended service endpoints can connect to a service, preventing unauthorized access.
• No Shared Dependencies: Traffic between consumer and producer VPC networks uses Network Address Translation (NAT), eliminating the need for IP address coordination or other shared resource dependencies. This simplifies the deployment and scaling of managed services.
• High Performance: PSC traffic flows directly from consumer clients to producer backends without intermediate hops or proxies, resulting in line-rate performance, reduced latency, and increased bandwidth capacity.

Private Service Connect is ideal for scenarios where you need to securely and privately access services hosted by Google, third parties, or other organizations within Google Cloud. Common use cases include(diagram) —

Credit: Google Cloud Document

VPC Service Controls (VPC SC)

VPC Service Controls is a security feature in Google Cloud that helps organizations mitigate data exfiltration risks by creating security perimeters around sensitive Google Cloud resources. It provides an additional layer of security defense for Google Cloud services, independent of Identity and Access Management (IAM). While IAM focuses on who can access resources, VPC Service Controls focuses on where resources can be accessed from and what data can move across defined boundaries.

Key Features of VPC Service Controls

• Security Perimeters: VPC Service Controls allows you to define service perimeters that isolate sensitive Google Cloud resources (projects, networks, and services) into trusted boundaries. Communication is allowed freely within the perimeter, but by default, communication to Google Cloud services outside the perimeter is blocked.
• Data Exfiltration Prevention: The primary goal of VPC Service Controls is to prevent unauthorized data movement. It helps protect against accidental or malicious data exfiltration by restricting data access and transfer operations to resources within the defined perimeter.
• Context-Aware Access: VPC Service Controls enables context-aware access to resources based on client attributes such as identity type (service account or user), identity, device data, and network origin (IP address or VPC network). This allows for fine-grained control over who can access resources from where.
• Ingress and Egress Rules: You can configure ingress and egress rules to explicitly allow or deny traffic flow across perimeter boundaries. This provides granular control over data exchange between clients and resources separated by perimeters.
• Defense in Depth with IAM: VPC Service Controls complements IAM by providing a broader context-based perimeter security. It’s recommended to use both VPC Service Controls and IAM for a robust defense-in-depth strategy.

VPC Service Controls is crucial for organizations dealing with highly sensitive data or those subject to strict compliance regulations. Key use cases include(diagram):

Credit: Google Cloud Document

Sooo, is it PSC vs VPC SC — OR — PSC and VPC SC?

While both Private Service Connect and VPC Service Controls are critical for enhancing security in GCP, they serve distinct purposes and address different security challenges; hence, it is not incorrect to say that they aren’t mutually exclusive, but rather complementary.

Private Service Connect Vs VPC Service Controls

Let’s see how these two can be used in conjunction.

For example, in a healthcare company.

1. You have a project (Project-ML) that runs a sensitive machine learning service for analyzing medical images.
2. You have another project (Project-App) that runs a patient-facing web application.
3. The data (medical images and patient info) is highly sensitive and must be protected.

Here’s how you use both services for a defense-in-depth strategy:

1. Create a Security Boundary: You place Project-ML inside a VPC Service Controls perimeter. This ensures that the sensitive training data and the ML model itself cannot be copied out to an unauthorized location.
2. Enable Private Consumption: The web app in Project-App needs to call the ML service. You use Private Service Connect to publish the ML service from Project-ML and create a private endpoint for it in the Project-App VPC.

The result?

• The web app communicates with the ML service over Google’s private network. No public internet exposure.
• The sensitive data and the ML model in Project-ML are safely locked inside the VPC Service Controls perimeter, preventing exfiltration.

Conclusion

Private Service Connect (PSC) and VPC Service Controls (VPC SC) are distinct yet complementary GCP security services. PSC enables secure, private connectivity to managed services, ensuring traffic stays off the public internet and simplifying network architecture. VPC SC, conversely, provides a critical defense against data exfiltration by creating robust security perimeters around sensitive data and resources. For a comprehensive GCP security strategy, combining PSC for private communication channels and VPC SC for strong perimeter defense is recommended, allowing organizations to build highly secure and compliant cloud infrastructures.

Read my other tech blogs

Rahul Kumar Singh - Medium

Connect with me on LinkedIn: Rahul Kumar Singh

Clap and share this blog to show your support.