The advent of a product to enable the interaction with the database from a remote client has been a boon to the computing world. For the Oracle RDBMS, that product was SQL*Net (Net8 for Oracle8). SQL*Net enables the ability to connect to a database in Tokyo from a database in New York and share information between the two. While this ability has been a benefit to industry, it carries with it the potential for security breaches.
Connections via SQL*Net are
controlled by three files, the
TNSNAMES.ORA file, and the
SQLNET.ORA file. If you do not define the
database in these files (called “configuring the
Listener”), connecting to your database from a remote client is
virtually impossible. In an environment where the Oracle Names Server
is used, the third file,
SQLNET.ORA, defines the
location of the Names Server and the order in which a database
connection is determined. The
indicates either that the Names Server is to be checked first for a
database’s connection information or that the
TNSNAMES.ORA file is to be checked first.
You must configure these files if you are not going to use a Names Server, after installing the SQL*Net product on your system and in order to run a listener process on your system (see the section “About the Names Server” later in this chapter) as follows:
This is a required file on the database server, and it contains the configuration for the listener. ...