Enable SSH remote root login on CentOS and the Ubuntu operating system

We typically discourage remote root login as a security best practice, but if you need to remotely
Secure Shell (SSH) in to your server as the root user, use the following process for both CentOS®
and the Ubuntu® operating system:

1. Open the following configuration file with your favorite command line text editor, such as nano
   or vim, as the root user:

   /etc/ssh/sshd_config
   

2. Find the following line in the file:

   #PermitRootLogin no

3. Replace the commented-out line with the following line:

   PermitRootLogin yes

4. Save and close your text editor.

5. Test your change to ensure that your SSH configuration does not break when you reload the ssh
   service. Check the syntax with the following command:

   sshd -t
   

   You might need to run the command as a super user by adding sudo to the beginning of the command.
   If you are editing the file as a root user, you do not need to use sudo. If you receive a
   Permission denied response, use the following command:

   sudo sshd -t
   

   The server gives no response if the syntax is correct. You should see a response similar to the following:

   [root@testserver ~]# sshd -t
   [root@testserver ~]#
   

6. After you verify the syntax for your SSH configuration file, reload the ssh service. It is better to
   reload, rather than restart, so you aren’t disconnected from the server. Reload the ssh service with
   the following command:

    service sshd reload
    
   

   In CentOS 7 and later, you can use the systemctl reload sshd command instead of the service
   command to reload SSH. However, service works in both CentOS and the Ubuntu operating system.

7. After the reload completes, use the following command to check that sshd is running:

   service sshd status

The response should indicate that the service is currently running. You can now SSH into the server as
the root user.

Note: Most bad actors attempt to hack into a server as the root user, so Rackspace recommends
disabling the ability to log in as root remotely. Instead, Rackspace recommends that you use SSH to
access the server as a user with sudo privileges. Then, you can elevate to the root user after you
connect.