1. AWS EC2에 접속할 때 보안을 위해 .pem 파일을 사용해서 접속을 할 때가 있습니다. 그럴 때 자주 겪는 경고가 있지요.$ ssh -i ~/key/test.pem ubuntu@ec2-xx-xx-xx-xx.ap-northeast-2.compute.amazonaws.comThe authenticity of host 'ec2-xx-xx-xx-xx.ap-northeast-2.compute.amazonaws.com (xx.xx.xx.xx)' can't be established.ECDSA key fingerprint is SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.Are you sure you want to continue connecting (yes/n..