root@packer-virtualbox-iso:/var/www/.ssh# ls -l
total 12
-rwxrw-r-- 1 www-data www-data 1679 Jul 22 20:35 id_rsa
-rwxrw-r-- 1 www-data www-data  391 Jul 22 20:35 id_rsa.pub
-rwxrw-r-- 1 www-data www-data 1768 Jul 22 20:40 known_hosts
root@packer-virtualbox-iso:/var/www/.ssh# chmod 400 id_rsa
root@packer-virtualbox-iso:/var/www/.ssh# ls -l
total 12
-rwxrw-r-- 1 www-data www-data 1679 Jul 22 20:35 id_rsa
-rwxrw-r-- 1 www-data www-data  391 Jul 22 20:35 id_rsa.pub
-rwxrw-r-- 1 www-data www-data 1768 Jul 22 20:40 known_hosts