VPC Endpoints Demystified: Interface vs Gateway and Their Role in Secure Architectures

Amazon Virtual Private Cloud (VPC) endpoints are a critical component for creating secure and scalable architectures in AWS. They allow communication between your VPC and AWS services without exposing your traffic to the public internet. But not all VPC endpoints are created equal. This article breaks down the differences between VPC Interface Endpoints and VPC Gateway Endpoints, explores their use cases, and evaluates their role in enhancing security. We’ll also touch on how Interface Endpoints enable access to AWS global services from on-premises environments.

What are VPC Endpoints?

A VPC endpoint allows private connectivity between your VPC and supported AWS or third-party services, bypassing the need for an internet gateway, NAT gateway, or VPN connection. These endpoints fall into two categories:

• Interface Endpoints: Powered by AWS PrivateLink, these create Elastic Network Interfaces (ENIs) in your VPC.

• Gateway Endpoints: A route table mechanism for accessing S3 and DynamoDB.

VPC Interface Endpoint

A VPC Interface Endpoint leverages AWS PrivateLink to provide private connectivity to services over ENIs. This type of endpoint is ideal for:

1. AWS services: Connecting to services like CloudWatch, Secrets Manager, and Systems Manager.

2. Third-party services: Accessing partner SaaS solutions securely.

3. On-premises access: With hybrid connectivity (via AWS Direct Connect or VPN), you can extend private access to AWS services from your on-premises environment.

Key Features:

• Uses private IPs for connectivity.

• Works across Availability Zones (AZs) in a VPC.

• Supports many AWS global services, allowing access to these services from on-prem.

Security Benefits:

• Traffic never traverses the public internet.

• Integrated with AWS Identity and Access Management (IAM) policies.

• Simplifies compliance by keeping data within the AWS network.

Example Use Case: Accessing Secrets Manager from a private subnet in a vpc to securely retrieve credentials without internet exposure.

VPC Gateway Endpoint

A VPC Gateway Endpoint is designed for S3 and DynamoDB, using route tables to enable private connectivity. It does not require ENIs or PrivateLink.

Key Features:

• Simpler and more cost-effective than Interface Endpoints.

• Automatically scales without additional configuration.

• Restricted to specific AWS services (S3 and DynamoDB).

Security Benefits:

• Ensures all traffic to S3 or DynamoDB stays within the AWS network.

• Integrates with S3 bucket policies and VPC endpoint policies for fine-grained control.

Example Use Case: Data pipelines that require consistent, high-throughput access to S3 buckets from multiple instances within a VPC.

Interface vs Gateway Endpoints

Which Adds More Security?

While both endpoint types enhance security by removing the need for public internet access, Interface Endpoints offer additional control and flexibility:

• PrivateLink Integration: Traffic never leaves the AWS backbone, reducing exposure.

• IAM Policies: Allows granular control over access.

• Security Groups: You can associate one or more security group to interface endpoint ENI and control the traffic in/out to it.

• Cross-Account Access: Enables secure connections to third-party services.

Gateway Endpoints excel in simplicity and cost-effectiveness but are limited in scope and flexibility.

Accessing AWS Global Services from On-Prem with Interface Endpoints

One of the standout capabilities of Interface Endpoints is their ability to extend AWS service access to on-premises environments. Here’s how it works:

1. Hybrid Connectivity: Establish a Direct Connect or VPN connection between your on-premises network and your AWS VPC.

2. Route Traffic via Interface Endpoint: Configure DNS and routing rules to direct service requests through the Interface Endpoint.

3. Enhanced Security: Traffic remains private, compliant, and within the AWS global network.

This setup is particularly useful for accessing global services like Secrets Manager or Systems Manager, ensuring sensitive data remains secure.

Conclusion

Understanding when to use a VPC Interface Endpoint versus a Gateway Endpoint is crucial for designing secure and cost-efficient architectures. While Gateway Endpoints shine in their simplicity for S3 and DynamoDB, Interface Endpoints provide broader applicability and advanced security features, making them ideal for more complex use cases.

For organizations seeking to enhance hybrid connectivity, Interface Endpoints offer a robust solution to securely access AWS global services from on-premises environment