The AWS VPC Inbound Port Blocklist rule is designed to monitor and control inbound network traffic to AWS VPC resources. It specifically checks for any traffic that violates a predefined blocklist of inbound ports. The rule analyzes VPC Flow Logs and reports instances where a public IP address attempts to connect to a private IP address on a restricted port. For example, if traffic is observed on standard ports such as SSH (port 22), it triggers an alert indicating a potential security breach. Conversely, connections on allowed ports will not trigger an alert. The rule is enabled to provide high-severity insights into potential command-and-control activities or unauthorized access attempts via non-standard ports. The rule's effectiveness relies on accurate definition and maintenance of the port blocklist, which should be updated as necessary to match the organization's security policies.