The "UNPROTECTED PRIVATE KEY FILE" error message in Secure Shell (SSH) is usually seen when attempting to connect to a remote host using an SSH private key that has weak file permissions.
In SSH, a private key is used to authenticate the client to the server. It is important to keep the private key secure and protect it from unauthorized access.
If the file permissions on the private key are too permissive, it could allow anyone with access to the file to read or use the private key, which could compromise the security of the SSH connection.
To fix this error, you need to set the file permissions on the private key file to be more restrictive. The recommended file permissions for an SSH private key are 0600 (read-write for the owner, no access for others).
To set the file permissions on an SSH private key file to 0600, you can use the chmod command, like this:
chmod 0600 /path/to/private_key
This will set the file permissions on the private key file to 0600, which will protect it from unauthorized access.
You can find more information about file permissions and the chmod command in the relevant man pages by running man chmod in a terminal.