|Oracle Advanced Security Administrator's Guide
Release 2 (9.2)
Part Number A96573-01
This chapter describes how clients outside DCE can connect to Oracle servers in DCE, and how tnsnames.ora, a local naming configuration file, can be used for name lookup when CDS is accessible.
This chapter contains the following topics:
Clients without access to DCE and CDS can still connect to Oracle servers in DCE using TCP/IP or some other protocol if a listener is configured to do this. If a listener has been configured in the listener.ora file on the server, non-DCE clients can use normal Oracle9i and Oracle Net Services procedures to connect to an Oracle server in DCE.
In this case, DCE security is not available to clients. Also, service names are resolved to network addresses and located in a
The following section includes samples of listener.ora and tnsnames.ora files as they would be configured if a client from outside of DCE wanted to connect to Oracle database servers in a DCE environment.
At least the following two Oracle parameter files are needed for successful client/server communications; create and modify these files using a text editor:
The parameter files are described in the following sections:
The listener.ora file resides on the listener node. It defines listener characteristics and the addresses at which the listener listens.
In the following example, each element is displayed on a separate line, to show the file's structure. This is the recommended format, but you do not have to put each element on a separate line. Be sure to include all the appropriate parentheses, and to indent if you must continue an element on the next line.
This example assumes the UNIX operating system and the TCP/IP protocol for one listener, and the DCE protocol for another listener. A single listener can have multiple addresses. For example, instead of having two separate listeners for different database instances on a server node, you could have one listener for both, listening on both TCP/IP and on DCE. However, performance is improved with separate listeners.
#For all listeners, the following parameters list sample
This file resides on both the client and the server nodes. It lists the service names and addresses of all services on the network.
The following sample tnsnames.ora file maps the service name
ORATCP to the connect descriptor that includes a TCP/IP address and the service name
ORADCE to a connect descriptor that includes a DCE address.
ORATCP = (DESCRIPTION=
To access the DB1 database, a user can use
ORATCP to identify the appropriate connect descriptor.
Typically, names are resolved into network addresses by CDS. Although the main purpose of the
tnsnames.ora file (in the context of native naming adapters) is to load Oracle service names and network addresses into CDS, it could be used temporarily as a backup name resolution service if CDS is inaccessible.
To use the
tnsnames.ora file for name lookup and resolution, remove (or comment out) the "native name" parameters from the
sqlnet.ora file on the client. To comment out the lines, add a pound sign (#) at the beginning of each line.
You can use
tnsnames.ora for name lookup and resolution when DCE CDS is unavailable if you have
TNSNAMES listed as a value for the
NAMES.DIRECTORY_PATH parameter in the
sqlnet.ora file on the client.
This parameter enables you to list more than one names resolution method. The methods are tried in order. In this example, DCE is attempted first. If it is unsuccessful, TNSNAMES is tried next.