Securing the AWS EC2 instance is the first thing you have to think while creating it. This post specifically talks about how to secure SSH/RDP port on your AWS EC2 Instances and how not to open port 22/3389 to the Internet (0.0.0.0/0).

Follow it on https://medium.com/@vijaykodam/how-to-login-securely-to-your-aws-ec2-instance-cc94fff5ebd2