Please login as the ec2-user user

When login to yous amazon ec2 instance via putty or command line it is possible that you get this error.

Authenticating with public key "imported-openssh-key"
Please login as the ec2-user user rather than root user.



Then login as user "ec2-user" instead of root user and if you want to run commands as root user, use sudo command or switch the user to root

eg:
#sudo vi /etc/dhcpd.conf

or
#sudo su -
Then you'll become root user.