PrivateLink & VPC peering for inference

Why public internet routing weakens your security posture

When your application sends prompts to an inference API over the public internet, the traffic traverses infrastructure you don't control — ISPs, transit networks, and the provider's load balancers. You can encrypt it, and you should. But the data has left your network boundary before the first token is generated. For regulated workloads, that's a compliance finding. For security-conscious teams, it's an unnecessary attack surface. Private connectivity — PrivateLink, VPC peering, or Direct Connect — removes that surface. Prompts travel over the cloud provider's backbone, inside your VPC, and the only endpoints that can reach the inference gateway are the ones you explicitly authorize.

PrivateLink vs VPC peering vs Direct Connect

Three private connectivity options, each for a different topology. Choosing the right one depends on whether the inference gateway lives in your VPC, in a separate VPC, or across your on-prem boundary:

• AWS PrivateLink. Creates an interface VPC endpoint in your VPC that maps to the inference service. Traffic stays on the AWS backbone and never hits the internet. Private DNS means your application connects to inference.your-vpc.internal and the endpoint handles the routing. Best when the inference gateway is in a separate VPC or managed account.
• VPC peering. Connects two VPCs directly over AWS networking. Useful when you manage both the application VPC and the inference VPC yourself. Simpler than PrivateLink for same-account deployments but requires non-overlapping CIDR ranges and route table management.
• AWS Direct Connect. Extends your on-prem network into AWS over a dedicated physical connection. Use this when the GPUs are in AWS but your application is in your data center — common in hybrid on-prem/VPC deployments.

Setting up an interface VPC endpoint

PrivateLink connects your application to the inference gateway through an elastic network interface in your subnet. The gateway's security group controls which VPC endpoints can reach it. Your application sees a private DNS name, not a public IP. Here's the Terraform for the endpoint side:

resource "aws_vpc_endpoint" "hyperinfer" {
    vpc_id              = aws_vpc.main.id
    service_name        = "com.hyperinfer.inference"
    vpc_endpoint_type   = "Interface"
    subnet_ids          = aws_subnet.private[*].id
    security_group_ids  = [aws_security_group.inference.id]
    private_dns_enabled = true
  }

What private DNS gives you

With private_dns_enabled = true, AWS Route 53 Resolver maps the public DNS name of the inference service to the private IP of your VPC endpoint. Your application code connects to the same hostname whether it's running in your VPC or not — but inside the VPC, the traffic resolves locally and never leaves the AWS network. No code changes needed. No separate DNS configuration. You get private routing without your application knowing it happened.

Data residency and the compliance angle

Private connectivity reinforces data residency claims in ways that public internet routing cannot. When traffic stays on the AWS backbone within a single region — Frankfurt to Frankfurt, Singapore to Singapore — you have documentation from the cloud provider that the data never transited a public network. That's concrete evidence for auditors reviewing your GDPR compliance posture. Pair it with single-tenant GPUs in the same region and zero data retention, and you've eliminated the three most common data-residency audit findings: cross-region traffic routing, prompts stored in multi-tenant logging pipelines, and data at rest in a provider's environment. The network layer is only one piece, but it's the piece most teams overlook. See HyperInfer's compliance documentation for the full control mapping.

The alternative you shouldn't use

IP allowlists. They're better than nothing, but they're a perimeter control on a public endpoint — a locked door on a house with windows. A misconfigured load balancer, a rotated IP range, or a traffic-routing change can expose your endpoint without warning. PrivateLink makes the endpoint unreachable from the public internet by construction, not by configuration. For a full VPC deployment walkthrough, the networking step is the step that turns a demo into a production architecture.