For this you will want to use one of the following keys, followed by the values you’d like to permit or deny: DenyUsers, AllowUsers, DenyGroups, and AllowGroups. For those instances, you can allow and deny both users and groups. If you have multiple people who access your server, you may want to restrict the use of ssh altogether. To adjust the port, edit the main ssh daemon at “/etc/ssh/sshd_config.” You’ll want to add a new line specifying the port following the syntax Port XXXXX. In addition to that, you will need to ensure that anyone who accesses through this port is aware of the new number, and that new port number is utilized by any client or software. However, this will not limit those who scan for open ports and attack whatever is open. This will limit most people who are utilizing a script going to that port, or who are attacking that port manually. You are able to change the port number from 22 (the default) as a way to limit the direct hits to your server on that port. PermitRootLogin no Change the port number
