SHELL

warning unprotected private key file ec2

sudo chmod 600 /path/to/my/key.pem 

aws ssh warning unprotected private key file

sudo chmod 600 ~/.ssh/id_rsa
sudo chmod 600 ~/.ssh/id_rsa.pub

warning unprotected private key file problem on aws instance

add sudo before ssh and then execute
sudo ssh -i "ma.pem" ec2-user@ec2-54-83-120-103.compute-1.amazonaws.com