The default value of the special port is set to the listener port +1.
However, by using the hidden parameter below, it is possible to specify and use a particular port.

_LSNR_SPECIAL_PORT

This parameter requires a restart, and the port must be set in tbdsn.tbr to be usable. 

Method

1. Assign the special port to a specific port in the environment file

2. Modify the tbdsn.tbr file

3. Connect through the special port