In the AWS documentation it says
Security groups are stateful — if you send a request from your instance, the response traffic for that request is allowed to flow in regardless of inbound security group rules.
I don't understand how this behavior is regarded as stateful? How would a stateless situation proceed?
I suppose that the response traffic would depend on some type of rule, but how does this relate to state?
Thanks
if you send a request from your instance
this action changes the state of the access logic. Behavior after this action is different from behavior before it. They are saying the incoming traffic might have been blocked without this. For example if some other external source like an SQS queue had triggered the incoming traffic.