The firewall filter should allow COM_PING and other similar commands to
pass through as they are mainly used to check the status of the backend
server or to display statistics. The COM_PROCESS_KILL is the exception as
it affects the state of the backend server. This is better controlled with
permissions in the server than in the firewall filter.
Commands that require special grants aren't allowed to pass as they are
mainly for maintenance purposes and these should not be done through the
firewall.
fdee329198