Amazon SOA-C03 Exam - Topic 1 Question 13 Discussion

SSH access to a Linux EC2 instance requires inbound TCP port 22 to be allowed by the instance's security group from the administrator's source IP address. A timeout usually indicates that network traffic is being blocked before the SSH service can respond. Since the instance is in a public subnet and has a public IP address, the most likely missing control is an inbound security group rule. Security groups are stateful, so return traffic is automatically allowed after inbound SSH is permitted. Adding a route for the engineer's IP address is not needed because public subnets use a default route to the internet gateway. An outbound-only NACL or security group rule does not allow inbound SSH initiation. Therefore, the correct remediation is to allow inbound SSH from the engineer's public IP.