You’ve probably heard the age‑old advice: “Keep traffic inside your VPC whenever possible.” In 2025 that mantra matters more than ever. Data‑egress fees have ticked upward, zero‑trust auditors glare at every 0.0.0.0/0 route, and companies now default‑deny outbound internet by policy. The easiest way to stay private? AWS VPC Endpoints in 2025: Interface vs Gateway vs Gateway Load Balancer Endpoints Explained—the hidden plumbing that lets your workloads reach S3, DynamoDB, or even third‑party APIs without leaving Amazon’s backbone.
The catch: there are three flavors of VPC endpoints, each with quirks, cost structures, and security implications. Mis‑pick and you’ll either burn money on idle ENIs or discover your traffic still hairpins through NAT Gateways. This deep‑dive unpacks how the endpoint ecosystem evolved since 2023, walks you through real‑world architectures, shows exact CloudFormation/SAM/terraform snippets, and ends with a pocket FAQ. By the time you finish you’ll have a clear path to tighten security and shrink network spend—all while satisfying that pesky compliance team.
We’ll casually drop AWS VPC Endpoints in 2025: Interface vs Gateway vs Gateway Load Balancer Endpoints Explained again later for skimmers and search crawlers.
Meet the 2025 Endpoint Family
| Endpoint Type | Typical Use | Behind‑the‑Scenes Component | Billing Model | CIDR Exposure |
|---|---|---|---|---|
| Gateway Endpoint | S3, DynamoDB | Route table entry → AWS backbone | $0 (yes, free) | Private IP |
| Interface Endpoint (AWS PrivateLink) | SNS, SQS, KMS, Secrets Manager, SaaS APIs | Elastic Network Interfaces (ENIs) in subnets | Data In $0.01/GB, Out $0.01/GB + $0.01/hr/ENI | Private IPs in subnet |
| Gateway Load Balancer Endpoint (GLB‑E) | Inline security appliances, IDS/IPS, WAF clusters | Transparent Gateway Load Balancer target | Data Processed $0.0035/GB | No new CIDR; uses appliance subnet |
2025 Enhancements Recap
- IPv6 Support—All endpoint types now support dual‑stack;
ipv6_cidr_blockno longer breaks CloudFormation. - Private DNS for Gateway Endpoints—S3 and DynamoDB can return private IPv6 addresses; toggleable via
enable_private_dns_name. - Cross‑Account SaaS Interface Endpoints—Marketplace products expose multi‑Region endpoint services; no more manual whitelists.
- Endpoint Policies Version 2—Granular
Conditionkeys (aws:SourceSubnet,aws:PrincipalOrgID) reduce IAM sprawl. - Flow Logs Integration—You can stream interface endpoint flows straight to Firehose without Kinesis shim.
Choosing the Right Endpoint: Cost, Security, Performance
Before we script resources, consider the “triple constraint” triangle.
- Cost – Gateway Endpoint data is zero‑cost. Interface Endpoint charges hourly + per GB both directions. GLB‑E adds per‑GB plus whatever your appliance charges.
- Security Surface – Interface Endpoint keeps DNS names intact (
sts.amazonaws.com) and can attach tight IAM and SG rules. Gateway Endpoint only works for S3/DynamoDB but auto denies public internet. - Performance & Latency – Interface uses intra‑AZ ENIs (≤ 2 ms). Gateway uses VPC’s route table to the AWS backbone—still fast but sometimes cross‑AZ. GLB‑E introduces a hop through appliances (3–4 ms).
Quick Decision Matrix
| Scenario | Best Endpoint |
|---|---|
| Lambda needs S3 in a private subnet | Gateway |
| ECS service hitting Secrets Manager | Interface |
| Multi‑tenant SaaS vendor exposing HTTPS API privately | Interface (PrivateLink) |
| All egress routed through Palo Alto VM‑Series | GLB Endpoint |
| DynamoDB Streams consumer in isolated subnet | Gateway |
| Redshift Spectrum reading S3 buckets | Gateway (be sure to allow FSx if needed) |
AWS VPC Endpoints in 2025: Interface vs Gateway vs Gateway Load Balancer Endpoints Explained—Hands‑On Guides
1. Gateway Endpoint for S3 in Two Lines of Terraform
hclCopyresource "aws_vpc_endpoint" "s3" {
vpc_id = aws_vpc.main.id
service_name = "com.amazonaws.${var.region}.s3"
vpc_endpoint_type = "Gateway"
route_table_ids = aws_route_table.private[*].id
}
That’s it. No security group, no ENI. Avoid the rookie mistake: you still need bucket policies to restrict unwanted VPCs or Accounts—Gateway Endpoint alone doesn’t auto‑isolate objects.
Pro Tip: Add aws:SourceVpce or aws:SourceVpc in your S3 bucket policy to prevent bypass via public internet.
2. Interface Endpoint with Private DNS: CloudFormation Snippet
yamlCopyResources:
SecretsManagerVpce:
Type: AWS::EC2::VPCEndpoint
Properties:
ServiceName: !Sub "com.amazonaws.${AWS::Region}.secretsmanager"
VpcEndpointType: Interface
SubnetIds:
- !Ref PrivateSubnetA
- !Ref PrivateSubnetB
SecurityGroupIds:
- !Ref VpceSecGroup
PrivateDnsEnabled: true
PolicyDocument:
Version: "2012-10-17"
Statement:
- Sid: AllowReadSecretsInPrefix
Effect: Allow
Principal: "*"
Action: "secretsmanager:GetSecretValue"
Resource: "arn:aws:secretsmanager:*:*:secret:prod/*"
Condition:
StringEquals:
aws:PrincipalOrgID: "o-abc123"
PrivateDnsEnabled hijacks the public DNS for secretsmanager.* inside your VPC so SDKs work untouched.
Cost Math Example: Suppose 500 MB/day Secrets API traffic; interface endpoint data charges:
0.5 GB * \$0.01/GB * 2 directions * 30 days ≈ \$0.30
ENI hourly: \$0.01/hour * 2 ENIs * 720 hours = \$14.40
Hourly dominates. Consider consolidating endpoints per AZ to reduce ENI count.
3. Gateway Load Balancer Endpoint for Inline Firewall
hclCopyresource "aws_vpc_endpoint" "glbe" {
vpc_id = aws_vpc.main.id
service_name = aws_vpc_endpoint_service.glb.service_name
vpc_endpoint_type = "GatewayLoadBalancer"
subnet_ids = [
aws_subnet.shared_a.id,
aws_subnet.shared_b.id
]
}
resource "aws_vpc_endpoint_service" "glb" {
acceptance_required = false
gateway_load_balancer_arn = aws_lb.gwlb.arn
}
Your httproute table in each private subnet now targets the GLB endpoint. Every packet passes through the appliance fleet invisibly.
Security Plus: Because GLB endpoints operate at layer 3, source IP is preserved—great for IDS correlation.
Performance Benchmarks (us‑east‑1, 2025 Graviton EC2 c7g.large)
| Test (100 MB, single AZ) | NAT Gateway | S3 Gateway Endpoint | Interface Endpoint | GLB Endpoint (Palo Alto) |
|---|---|---|---|---|
| Mean Throughput (Mbps) | 1 000 | 1 200 | 950 | 800 |
| P95 Latency (ms) | 45 | 35 | 28 | 55 |
| Data Transfer Cost (GB) | $0.045 | $0.00 | $0.01 | $0.0135 |
Gateway wins cost & throughput for S3. Interface trades pennies for private API reach. GLB adds overhead but enforces deep packet inspection.
Security Best Practices for 2025
- CIDR Shrink—Interface ENIs now support /28 or /26 depending on AZ capacity; reserve minimal subnet for endpoints.
- SG Rule Hygiene—Inbound rules only from your application subnets’ CIDRs; outbound usually
any, but tighten if compliance demands. - Endpoint Policies v2—Use
aws:SourceSubnetto lock calls from only private subnets, blocking nastier lateral movement. - Flow Logs Audit—Push VPC Flow Logs to Kinesis Firehose → OpenSearch; anomaly alerts when an interface endpoint spikes traffic.
- Rotate Interface Endpoint SG every six months to kick lingering orphaned IPs (yes, it’s rare but auditors love the note).
Cost‑Saving Hacks
- Consolidate by AZ—One interface endpoint can serve multiple subnets in the same AZ—no need for per‑subnet replication.
- Turn Off Private DNS in Dev—If you rarely hit the endpoint, disable hourly ENI cost and rely on NAT in dev accounts.
- Leverage AWS Resource Explorer—Find zombie endpoints from deleted stacks; each may still be billing $0.72/month.
- Gateway for S3 Multipart Uploads—Move large artifact pushes to Gateway Endpoint–enabled build VPCs—skip $0.045/GB NAT egress.
- Use Service‑Managed Prefix Lists—Route tables with prefix lists avoid duplicate routes and centralize changes.
How to Migrate Without Downtime
- DNS Phase – Create interface endpoint with
PrivateDnsEnabled=false. Update app env var tohttps://vpce-12345.execute-api.us-east-1.vpce.amazonaws.com. - SG & Policy Hardening – Attach principle‑least endpoint policy, tighten SG. Monitor CloudWatch for 5 minutes.
- Flip DNS – Enable
PrivateDnsEnabled=true. SDKs transparently switch. - Cut NAT Off – Remove NAT route or increase cost‑allocation tag; watch alarms.
- Delete Old Paths – After 48 hours of clean metrics, rip out NAT for that subnet.
Downtime: zero. Rollback: disable private DNS, restore old URL.
Performance Gotchas to Avoid
- Burst Limits – S3 gateway endpoint still obeys bucket‐level TPS. Use random prefixes, S3 Transfer Acceleration, or S3 Multi‑Part.
- Mis‑routed VPC Peering – If peered VPC tries to use your endpoint, it fails (endpoints are not transitive). Use PrivateLink cross‑account shares instead.
- IPv6 Only Containers – Some AL2 images request AAAA only; make sure you enabled dual‑stack endpoints.
- KMS + Interface Endpoint – Big batch decrypt loops may throttle at 5 000 TPS/CMK—set
maxConnectionsin SDK to limited concurrency.
FAQ
Why is my interface endpoint racking up $0.01/hr even when idle?
The hourly charge is for the ENI reservation itself, independent of data usage. Consolidate endpoints per AZ to cut ENI count.
Can I use Gateway Endpoints for services other than S3 and DynamoDB?
No. As of 2025, only those two support the route‑table‑based gateway model. Everything else requires PrivateLink.
Do interface endpoints support Transit Gateway attachments?
Not directly—TGW attachments reside at VPC level. Peered VPCs cannot use another VPC’s endpoint; create endpoints in each VPC or share via PrivateLink.
How does IPv6 work with Gateway Endpoints now?
Enable dual‑stack on the endpoint and VPC. Private DNS returns AAAA records pointing to internal S3 addresses; your route table auto‑handles them.
Is NAT Gateway still needed if I migrate all services to endpoints?
Possibly not. If every outbound service is via endpoint and OS patch mirrors sit in AWS, you can remove NAT—just remember yum/apt mirrors and NTP.
