Let me write a small HOW-TO for checking your Oracle Database without using the tnsnames.ora
This is written thanks to the help of my good friend EricTRA.
He provided me helpfull links and helped me for getting the solution.
This being said, here is the link which guided me : Helpfull Link !!
So, I'm going to write this HOW-TO regarding the link and a plugin for Nagios and if you have an Oracle Database, this is the place you want to be....