You can use DSCC to perform this task. For information, see Directory Service Control Center Interface and the DSCC online help.
Disable the LDAP clear port.
To disable the non secure point, you must bind to the LDAP secure port. This example shows a bind to the default LDAP secure port, 1636, on the host server host1.
$ dsconf set-server-prop -h host1 -P 1636 ldap-port:disabled
Restart the server for the change to take effect.
$ dsadm restart /local/ds
You can now no longer bind on the non secure port 1389.