How can connectivity be established between service while meeting the security requirements?
Create a VPC peering connection between the VPCs. Use security groups on the instances to allow traffic from the security group IDs that are permitted to call the microservice. Apply network ACLs and allow traffic from the local VPC and peered VPCs only. Within the task definition in Amazon ECS for each of the microservices, specify a log configuration by using the awslogs driver. Within Amazon CloudWatch Logs, create a metric filter and alarm off of the number of HTTP 403 responses. Create an alarm when the number of messages exceeds a threshold set by the Security team.
Ensure that no CIDR ranges are overlapping, and attach a virtual private gateway (VGW) to each VPC. Provision an IPsec tunnel between each VGW and enable route propagation on the route table. Configure security groups on each service to allow the CIDR ranges of the VPCs in the other accounts. Enable VPC Flow Logs, and use an Amazon CloudWatch Logs subscription filter for rejected traffic. Create an IAM role and allow the Security team to call the AssumeRole action for each account.
Deploy a transit VPC by using third-party marketplace VPN appliances running on Amazon EC2, dynamically routed VPN connections between the VPN appliance, and the virtual private gateways (VGWs) attached to each VPC within the region. Adjust network ACLs to allow traffic from the local VPC only. Apply security groups to the microservices to allow traffic from the VPN appliances only. Install the awslogs agent on each VPN appliance, and configure logs to forward to Amazon CloudWatch Logs in the security account for the Security team to access.
Create a Network Load Balancer (NLB) for each microservice. Attach the NLB to a PrivateLink endpoint service and whitelist the accounts that will be consuming this service. Create an interface endpoint in the consumer VPC and associate a security group that allows only the security group IDs of the services authorized to call the producer service. On the producer services, create security groups for each microservice and allow only the CIDR range of the allowed services. Create VPC Flow Logs on each VPC to capture rejected traffic that will be delivered to an Amazon CloudWatch Logs group. Create a CloudWatch Logs subscription that streams the log data to a security account.
Explanations:
VPC peering does not scale well for 200 accounts. Using security groups for inter-service communication is not optimal for the large number of services, and relying on ECS log configurations and metric filters does not provide a comprehensive network traffic monitoring solution.
Using IPsec tunnels with VGWs and route propagation is overly complex and not suitable for multiple accounts. While VPC Flow Logs provide network traffic monitoring, the method described is cumbersome and requires managing tunnel configurations across many VPCs, which isn’t efficient for the scale required.
Deploying third-party VPN appliances adds unnecessary complexity. It requires manual installation and management of VPN appliances, which is not an ideal solution for interconnecting 200 accounts securely and efficiently. This option lacks scalability and incurs additional operational overhead.
This solution leverages AWS PrivateLink for secure, private connectivity between VPCs, avoiding the public internet. It uses security groups to control which services can communicate with each other and VPC Flow Logs for monitoring denied traffic. This approach scales well and meets the security requirements effectively.
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Create a Network Load Balancer (NLB) for each microservice. Attach the NLB to a PrivateLink endpoint service and whitelist the accounts that will be consuming this service. Create an interface endpoint in the consumer VPC and associate a security group that allows only the security group IDs of the services authorized to call the producer service. On the producer services, create security groups for each microservice and allow only the CIDR range of the allowed services. Create VPC Flow Logs on each VPC to capture rejected traffic that will be delivered to an Amazon CloudWatch Logs group. Create a CloudWatch Logs subscription that streams the log data to a security account.