Protect the listner
From OWASP
http://www.oracle.com/technology/pub/articles/project_lockdown/phase1.html#1.7
www.integrigy.com/security-resources/whitepapers/Integrigy_Oracle_Listener_TNS_Security.pdf Page 17
http://www.oracle.com/technology/pub/articles/project_lockdown/phase1.html#1.7
www.integrigy.com/security-resources/whitepapers/Integrigy_Oracle_Listener_TNS_Security.pdf Page 17