A developer deploys a web application on an Amazon EC2 instance and updates its security group to permit inbound traffic on port 80. Although no outbound rules are modified, the instance can successfully return response traffic to the clients. Which characteristic of security groups explains why this outbound traffic is allowed?
- Security groups are stateful, meaning allowed inbound traffic is automatically permitted to flow outbound.Answer
- BNetwork Access Control Lists (Network ACLs) are stateless, which automatically permits all outbound response traffic at the instance level.
- CAmazon GuardDuty automatically detects safe inbound connections and dynamically bypasses the outbound rule evaluation.
- DAWS manages operating system firewalls to allow return traffic under the AWS shared responsibility model.
Answer
Security groups are stateful, meaning allowed inbound traffic is automatically permitted to flow outbound.
Security groups are stateful, which means that any rule permitting inbound traffic automatically permits the corresponding outbound response traffic, regardless of the outbound rules configured.
Step-by-Step Solution
Key Concept
Security groups are stateful firewalls that control inbound and outbound traffic at the Amazon EC2 instance level, automatically allowing return traffic.