First security steps when setting up any new internet facing linux server:

• Create a new user account
  • # adduser username
  • # passwd username
  • # usermod -aG wheel username
• Send SSH key
  • scp id_rsa.pub username@hostname:/home/username/id_rsa.pub
  • $ mkdir ~/.ssh
  • $ cat id_rsa.pub >> ~/.ssh/authorized_keys
  • $ chmod 700 ~/.ssh
  • $ chmod 600 ~/.ssh/authorized_keys
• Ensure SSH key authentication works
  • Disconnect and then reconnect, you should get prompted for your private key password not your server password (you did provide a password for your private key, right?!)
  • Do not disable “PasswordAuthentication” option below unless you are positive you are authentication SSH via keys – you will be locked out of your server and no longer able to SSH in.
• Disable Root SSH, Set Protocol 2 and Password SSH
  • $ sudo yum install -y nano
  • $ sudo nano /etc/ssh/sshd_config
    • PermitRootLogin no
    • Protocol 2
    • PasswordAuthentication no
  • $ sudo service sshd restart
  • Ensure you can still SSH back into the box using your key only.
• Update packages
  • $ sudo yum upgrade
• Reboot
  • $ sudo reboot