Explanation

AWS WAF (Web Application Firewall) is the correct service for this requirement because:

1. Purpose: AWS WAF is specifically designed to protect web applications from common web exploits by allowing you to create custom rules to filter and control inbound web traffic.

2. Functionality: It enables you to create custom conditions to:

   • Block or allow requests based on IP addresses
   • Filter based on HTTP headers, HTTP body, or URI strings
   • Protect against SQL injection attacks
   • Mitigate cross-site scripting (XSS) attacks
   • Set rate-based rules to limit request rates

3. Comparison with other options:

   • Amazon GuardDuty: A threat detection service that continuously monitors for malicious activity and unauthorized behavior (not for custom traffic filtering)
   • Amazon Macie: A security service that uses machine learning to discover, classify, and protect sensitive data (not for web traffic filtering)
   • AWS Shield: A managed Distributed Denial of Service (DDoS) protection service (provides automatic protection rather than custom rule-based filtering)

4. Integration: AWS WAF can be deployed on Amazon CloudFront, Application Load Balancer (ALB), or Amazon API Gateway, making it suitable for protecting web applications hosted on EC2 instances.

Key Takeaway: When you need to implement custom conditions to filter and control inbound web traffic for web applications, AWS WAF is the appropriate AWS service.