SSH: WARNING: UNPROTECTED PRIVATE KEY FILE! Error and Solution

ssh -i suse-ec2-server-jp.pem root@ec2-xx-yy-zzz-yyy.compute-1.amazonaws.com

I am getting the following error:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: UNPROTECTED PRIVATE KEY FILE! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0440 for 'suse-ec2-server-jp.pem' are too open.
It is recommended that your private key files are NOT accessible by others.
This private key will be ignored.
bad permissions: ignore key: suse-ec2-server-jp.pem
Password:

How do I fix this problem and login using ssh command?

chmod command syntax to fix file warnings

The syntax is:
chmod 0400 file
chmod 0400 /path/to/file

If suse-ec2-server-jp.pem is located in $HOME/.ssh/ directory, try:

## set permission on file ##
chmod 0400 $HOME/.ssh/suse-ec2-server-jp.pem 
 
## Make sure dir containing the suse-ec2-server-jp.pem private key and other files set to 0700
chmod 0700 $HOME/.ssh/

Verify permissions with the ls -l command:

ls -ld $HOME/.ssh/
ls -l $HOME/.ssh/suse-ec2-server-jp.pem

Now, try ssh command as follows:

## for ubuntu Linux #
ssh -i $HOME/.ssh/suse-ec2-server-jp.pem ubuntu@ec2-xx-yy-zzz-yyy.compute-1.amazonaws.com
 
## for Suse ##
ssh -i $HOME/.ssh/suse-ec2-server-jp.pem ubuntu@ec2-xx-yy-zzz-yyy.compute-1.amazonaws.com
 
## For freebsd ##
ssh -i $HOME/.ssh/suse-ec2-server-jp.pem root@ec2-xx-yy-zzz-yyy.compute-1.amazonaws.com

Sample session:

Fig.01: Fixing “WARNING: UNPROTECTED PRIVATE KEY FILE!” on Linux/MacOS X/FreeBSD/Unix

Please note that this is not AWS EC2 or Ubuntu/Suse Linux or Apple OS X specific issue. This is an OpenSSH client specific security related issue. See ssh man page for more information.