In AWS, can a firewall be used when connecting two Virtual Private Clouds (VPCs) through VPC peering?

The correct answer highlights the flexibility of architecture in AWS when managing networking and security between Virtual Private Clouds (VPCs). When VPCs are connected through VPC peering, there is indeed no explicit gateway for that peering connection; however, the architecture allows for the use of subnets within the VPCs to establish security measures.

Subnets can be configured to include resources such as firewalls, which can be integrated into the architecture to provide security for the traffic flowing between the peered VPCs. This means that while the direct use of a firewall in the context of VPC peering itself may seem limited due to the lack of a direct gateway, one can utilize subnets to manage and control traffic. By segmenting subnets and deploying firewalls within those subnets, you effectively gain the ability to filter traffic on a more granular level.

This answer emphasizes the importance of understanding how AWS networking works and the ways in which you can implement security measures, even in scenarios where initial perceptions might suggest limitations. By using subnets intelligently, you create an architecture that allows for the incorporation of firewalls and better overall security between VPCs.