For all SSH accounts created with DirectAdmin, it adds the "AllowUsers" option to the /etc/ssh/sshd_config file. Â When DirectAdmin is installed, it will add "root" and "admin" to that file under the AllowUsers option. Â Any other users who have had SSH account on the system will also require to be added to that file in order to access the server via SSH.
*IMPORTANT: For systems who require the use of "su" to access the root account, but do not use "admin" to do it, that usename *must* be added to the /etc/ssh/sshd_config before logging out or else they will not be able to login and and turn won't be able to su to root any longer. Â This isn't as relevant for RedHat systems, because the default is to enable root login, but for most FreeBSD systems, su is required, and the starting use *must* be in the wheel group, which a newly created "admin" would not be.