TNS Listener TCP/IP Valid Node Checking

Abstract

Listener valid node checking may be used to prevent malicious or errant Oracle Net connections to DBMS instances. It’s a “poor man’s firewall” under control of the DBA. Production DBMS instances may by separated from test and development instances without additional hardware or firewall software simply by specifying a list of nodes that may contact the listener. Valid node checking is documented, but it is undocumented that the parameters are fully dynamic in Oracle10g and Oracle11g, such that the configuration may be enabled, changed, and removed without stopping and restarting the TNS Listener, rendering the feature much less intrusive.