It is possible that creation of an instance in Oracle Directory Server might end up with the following error message:
port number 389 is a privileged port.
This happens because all the ports less than 1024 on Linux are treated as privileged. Most of our well know ports like 389 for the LDAP, 80 for HTTP, 443 for HTTPS reside in this range of ports.
Linux enforces that the services cannot be created at the privileged ports until and unless the privileges are escalated.
In this particular case, we can start the instance using the following command:
sudo dsadm start <path-to-instance>
The main reason for need for extra privileges when we use the privileges may be because there is a chance that the firewalls do not block traffic from these ports. Any attacker who might be interested in stealing your data over the network could be opening such ports so that he could escape firewalls. To reduce the attack surface, it is enforced that the privileged port need root access.