Function of Oracle Net Parameter Files

In the context of Oracle Network Services, "Net parameter files" refer to configuration files that define how Oracle clients and servers communicate over a network.
Key Functions of Net Parameter Files:

• Defining Client/Server Connection Behavior: They specify parameters that govern how clients connect to the database servers, including naming methods, encryption settings, authentication services, and other networking related configurations.
• Controlling Naming Resolution: They influence how Oracle clients locate database services or net service names.
• Configuring Oracle Advanced Security Features: They can specify how encryption and data integrity are implemented for secure communication.
• Enabling Tracing and Logging: They allow for configuring logging and tracing options to help in troubleshooting and monitoring Oracle Net activity.

Common Net Parameter Files:

• sqlnet.ora: The primary profile configuration file for Oracle Net Services, specifying a wide range of settings for clients and servers related to naming, authentication, security, logging, etc.
• tnsnames.ora: A file that stores net service names, mapping aliases to connection descriptors that specify the network address of database services.
• listener.ora: A file defining the configuration of the Oracle Net Listener, including listening addresses, connection limits, and other parameters related to connection management.

In essence, Net parameter files are crucial for customizing and managing the network communication between Oracle clients and servers, allowing for optimal performance, security, and manageability in Oracle database environments

The Oracle Connection Manager Control utility (`cmctl`) has not been discontinued, but its usage has significantly decreased in modern cloud-based deployments and is not emphasized in Oracle Cloud Infrastructure (OCI) environments or typical cloud-enabled Oracle 19c architectures.
🟡 Clarification: What is cmctl?
`cmctl` is the command-line utility used to administer Oracle Connection Manager (CMAN), a lightweight session multiplexor and access control filter that can reduce network traffic and improve scalability in complex architectures.
Used primarily in:

• On-premise architectures
• Environments requiring connection filtering, firewall bypassing, or load balancing at the network level

🟢 Cloud-Preferred Alternatives in Oracle 19c and OCI:
In modern Oracle 19c deployments, especially in "cloud-enabled or autonomous environments", Oracle promotes tools and services that provide higher-level network and connectivity management without requiring CMAN. Here are the recommended equivalents or replacements:

1. Oracle Net Services in Oracle Cloud Infrastructure (OCI)
   • Managed through Oracle Cloud Console (GUI)
   • Integration with VCNs, Private Endpoints, and Service Gateways
   • No need for cmctl – cloud networking replaces much of CMAN’s function
2. Easy Connect Plus Syntax (19c+)
   • Simplifies connection strings without tnsnames.ora or listener.ora
   • Ideal for cloud-native apps or microservices
3. Oracle SQL*Net Tracing and Logging (diag tools)
   • Enhanced logging and diagnostics tools in sqlnet.ora for connection issues
4. Autonomous Database Connectivity Features
   • Uses Wallet-based secure connections
   • Managed endpoints – no cmctl or listener configuration required
5. Oracle Cloud Infrastructure Bastion Service
   • Acts like a replacement for Connection Manager when secure jump-access is needed

Feature	Legacy (On-prem)	Cloud (Oracle 19c/OCI)
Session multiplexing	cmctl, CMAN	Managed VCN/Endpoints
Connection access control	CMAN rules	OCI Security Lists, NSGs
Connection syntax	tnsnames.ora + cmctl	Easy Connect Plus + Wallet
Admin interface	CLI (cmctl)	OCI Console, REST APIs

✅ Conclusion: While `cmctl` still exists and can be used in Oracle 19c, Oracle's modern cloud strategy has moved away from manual network utilities like CMAN in favor of native cloud infrastructure tools. For cloud-based deployments, Oracle recommends using VCN configuration, bastion services, and easy connect with wallet-based authentication.

At this point, it is necessary to make an important distinction about Net management. As we mentioned, Oracle has provided several online interfaces to assist with Net configuration and management. These GUI tools include:

1. Oracle Net Configuration Assistant
2. Oracle Connection Manager: The Oracle Connection Manager Control utility enables you to administer Oracle Connection Managers. You can use its commands to perform basic management functions on one or more Oracle Connection Managers. Additionally, you can view and change parameter settings.
3. A router through which a client connection request may be sent either to its next hop or directly to the database server. Clients who route their connection requests through an Oracle Connection Manager can then take advantage of the session multiplexing, access control, or protocol conversion features configured on that Oracle Connection Manager.
4. Enterprise Manager

However, please note that these tools are not always suitable for large Oracle installations, especially those that are still running legacy Oracle versions. In addition, these tools are only front ends that populate the Oracle configuration files, and many experienced administrators prefer to edit the parameter files directly without the use of the GUI tools. Hence, an understanding of the syntax and functions of the parameter files is critical to a full understanding of Net.
In Oracle, any computer can serve as a Net client, a Net server, or as both a client and a server.

• SQLNET.CLIENT_REGISTRATION:
  Purpose: To set a unique identifier for the client computer. This identifier is passed to the listener with any connection request and is included in the Audit Trail. The identifier can be any alphanumeric string up to 128 characters long.
  Default: None Example

  SQLNET.CLIENT_REGISTRATION=1432
  

• Creating a Net Server
  To create a Net server, you need only install an Oracle database and create and successfully configure a listener.ora file to start the listener process. Once the files are properly configured, connectivity can be established by entering SQL*Plus and entering the TNS service name of the desired database. That is all there is to Net. If this sounds simplistic, it is because we have not yet looked into the internals of the parameter files. We will do so shortly.
  In the next lesson, we will look at the components of Oracle Network Services.