products-service

In Oracle, tnsnames.ora, sqlnet.ora, and listener.ora are key configuration files used for network communication between Oracle clients and databases. Here’s a breakdown of each:

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1. tnsnames.ora

Purpose:
Defines TNS aliases that map to network connection details (host, port, service name) for Oracle databases.

Location:

$ORACLE_HOME/network/admin/

Example:

MYDB =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = dbserver.example.com)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = orclpdb1.example.com)
    )
  )

Use Case:
Used by Oracle tools like SQL*Plus or applications to resolve a TNS alias to connection parameters.

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2. sqlnet.ora

Purpose:
Defines network configuration parameters, such as naming methods (like TNSNAMES or LDAP), encryption, and timeout settings.

Example:

NAMES.DIRECTORY_PATH = (TNSNAMES, EZCONNECT)

SQLNET.ENCRYPTION_SERVER = required
SQLNET.CRYPTO_CHECKSUM_SERVER = required
SQLNET.EXPIRE_TIME = 10

Use Case:

• Control how client resolves service names
• Enable encryption and security settings
• Manage connection expiration and keepalives

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3. listener.ora

Purpose:
Configures the Oracle Listener, which accepts incoming client connections and routes them to the appropriate database service.

Example:

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = dbserver)(PORT = 1521))
    )
  )

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = orcl)
      (ORACLE_HOME = /u01/app/oracle/product/21.0.0/dbhome_1)
    )
  )

Use Case:
Defines which databases the listener serves and on what network interface and port.

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4. ldap.ora (optional)

Purpose:
Used when Oracle uses LDAP directory naming (like Oracle Internet Directory) instead of tnsnames.ora.

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5. cman.ora (optional)

Purpose:
Configures Oracle Connection Manager, a lightweight connection proxy to manage traffic and multiplex connections.

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Summary Table

File	Purpose	Client or Server	Required
tnsnames.ora	Defines connection aliases	Client	No (if using EZCONNECT or LDAP)
sqlnet.ora	Sets network/security policies	Client & Server	Yes
listener.ora	Configures database listener	Server	Yes
ldap.ora	LDAP connection info	Client	Optional
cman.ora	Connection Manager config	Middle-tier	Optional

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Let me know if you’d like to see a working config for secure client-to-server connections!