Linux – Why can’t I ssh into the new EC2 Instance

I figured it out:

ssh -i ~/.ssh/aws_ec2 -v ec2-user@ec2-79-125-85-42.eu-west-1.compute.amazonaws.com

You need to use ec2-user as the username.

Most likely you have this in your /etc/ssh/sshd_config:

PermitRootLogin no

This is a good thing, however. If you want to perform privileged actions, you should do them with sudo or at least start a root shell with sudo -s.

There will likely be a reason for the failed login in /var/log/auth.log on the server. It doesn't look like you put the public key in /root/.ssh/authorized_keys on your server, which is where it needs to be for root to log in.

Buried in the fine print here is the titbit that the default user is admin, not root in the Debian AMI. That's where Amazon will have put the public key that matches the private key you downloaded. Use this:

ssh -i /Users/James/Documents/sshkeys/aws.pem admin@myec2ip

The default user is ec2-user in the Amazon AMI and ubuntu in the Ubuntu AMI. I don't know about any others.