Secure VPC connections in AWS Global Accelerator
When you add a Network Load Balancer, an internal Application Load Balancer, or an Amazon EC2 instance endpoint in AWS Global Accelerator, you enable internet traffic to flow directly to and from the endpoint in Virtual Private Clouds (VPCs) by targeting it in a private subnet. The VPC that contains the load balancer or EC2 instance must have an internet gateway attached to it, to indicate that the VPC accepts internet traffic. However, you don't need public IP addresses on the load balancer or EC2 instance. You also don't need an associated internet gateway route for the subnet.
This is different from the typical internet gateway use case in which both public IP addresses and internet gateway routes are required for internet traffic to flow to instances or load balancers in a VPC. Even if the elastic network interfaces of your targets are present in a public subnet (that is, a subnet with an internet gateway route), when you use Global Accelerator for internet traffic, Global Accelerator overrides the typical internet route and all logical connections that arrive through the Global Accelerator also return through Global Accelerator rather than through the internet gateway.
Note
Using public IP addresses and using a public subnet for your Amazon EC2 instances are not typical, though it’s possible to set up your configuration with them. Security groups apply to any traffic that arrives to your instances, including traffic from Global Accelerator and any public or Elastic IP address that is assigned to your instance ENI. Use private subnets to ensure that traffic is delivered only by Global Accelerator.
To learn more about working with ENIs, security groups, and Global Accelerator, see Requirements for endpoints with client IP address preservation.
Keep this information in mind when considering network perimeter issues and configuring IAM privileges related to internet access management. For more information about controlling internet access to your VPC, see this service control policy example.
