Amazon ECS integrates natively with Amazon VPC by deploying containerized tasks directly into specified subnets, allowing them to leverage standard cloud networking and security controls.

When using the recommended aws vpc network mode (the default for AWS Fargate), AWS automatically assigns a unique Elastic Network Interface (ENI) and a private IP address from your VPC subnet to every running task, making the containers behave just like isolated EC2 instances. This close relationship allows you to attach AWS Security Groups directly to your containers to tightly manage inbound and outbound firewall rules, while shielding your architecture by placing the tasks inside secure private subnets. For traffic distribution and system scale, an Application Load Balancer (ALB) sitting in the VPC can track these task private IPs dynamically, routing user traffic safely across multiple Availability Zones without manual intervention. Finally, your containers can communicate privately with other AWS services like Amazon ECR and CloudWatch using VPC Endpoints (AWS PrivateLink), which completely keeps your data off the public internet, lowering costs and minimizing your infrastructure's attack surface.