WARNING: UNPROTECTED PRIVATE KEY FILE! when trying to SSH into Amazon EC2 Instance

Question

I\'m working to set up Panda on an Amazon EC2 instance. I set up my account and tools last night and had no problem using SSH to interact with my own personal instance, but

Answer 1

Change the File Permission using chmod command

sudo chmod 700 keyfile.pem

Answer 2

Make sure that the directory containing the private key files is set to 700

chmod 700 ~/.ec2

Answer 3

On windows, Try using git bash and use your Linux commands there. Easy approach

chmod 400 *****.pem

ssh -i "******.pem" ubuntu@ec2-11-111-111-111.us-east-2.compute.amazonaws.com

Answer 4

I am thinking about something else, if you are trying to login with a different username that doesn't exist this is the message you will get.

So I assume you may be trying to ssh with ec2-user but I recall recently most of centos AMIs for example are using centos user instead of ec2-user

so if you are ssh -i file.pem centos@public_IP please tell me you aretrying to ssh with the right user name otherwise this may be a strong reason of you see such error message even with the right permissions on your ~/.ssh/id_rsa or file.pem

Answer 5

The solution is to make it readable only by the owner of the file, i.e. the last two digits of the octal mode representation should be zero (e.g. mode 0400).

OpenSSH checks this in authfile.c, in a function named sshkey_perm_ok:

/*
 * if a key owned by the user is accessed, then we check the
 * permissions of the file. if the key owned by a different user,
 * then we don't care.
 */
if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
    error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
    error("@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @");
    error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
    error("Permissions 0%3.3o for '%s' are too open.",
        (u_int)st.st_mode & 0777, filename);
    error("It is required that your private key files are NOT accessible by others.");
    error("This private key will be ignored.");
    return SSH_ERR_KEY_BAD_PERMISSIONS;
}

See the first line after the comment: it does a "bitwise and" against the mode of the file, selecting all bits in the last two octal digits (since 07 is octal for 0b111, where each bit stands for r/w/x, respectively).

Answer 6

To fix this,

1. you’ll need to reset the permissions back to default:

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

   If you are getting another error:

   • Are you sure you want to continue connecting (yes/no)? yes
   • Failed to add the host to the list of known hosts (/home/geek/.ssh/known_hosts).

2. This means that the permissions on that file are also set incorrectly, and can be adjusted with this:

   sudo chmod 644 ~/.ssh/known_hosts
   

3. Finally, you may need to adjust the directory permissions as well:

   sudo chmod 755 ~/.ssh
   

This should get you back up and running.