Oracle Database Admin (DBA) Tutorial: Network Configuration

In its most basic form, Oracle uses three files (listener.ora, tnsnames.ora & sqlnet.ora) for network configuration.

1.   Listener.ora

The listerner.ora file contains server side network configuration parameters. It can be found in the "$ORACLE_HOME/network/admin" directory on the server. 

Ex:-

LISTENER =

  (DESCRIPTION_LIST =

    (DESCRIPTION =

      (ADDRESS = (PROTOCOL = TCP)(HOST = dba_vm)(PORT = 1521))

      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))

    )

  )

SID_LIST_LISTENER =

  (SID_LIST =

    (SID_DESC =

      (SID_NAME = CNTR)

      (ORACLE_HOME = /u01/app/oracle/product/11.2.0.2/db_1)

    )

)

lsnrctl commands

1.     Start a listener

If the listener has not been started, start it with the command:

lsnrctl> start listener_name

2.     Check the status with the STATUS command:

lsnrctl lsnrctl> status listener_name

3.     Check registered services

To see what database services is registered with a listener:

lsnrctl> services listener_name

4.     Stop a listener

To stop a database listener:

lsnrctl> stop listener_name

5.     Reload a listener

To reload a database listener (stop and restart without disrupting the service):

lsnrctl> reload listener_name

2.   tnsnames.ora

The "tnsnames.ora" file contains client side network configuration parameters. It can be found in the "$ORACLE_HOME/network/admin" directory on the client. This file will also be present on the server if client style connections are used on the server itself.

Ex:-

CNTR =

  (DESCRIPTION =

    (ADDRESS = (PROTOCOL = TCP)(HOST = rac1)(PORT = 1521))

    (CONNECT_DATA =

      (SERVER = DEDICATED)

      (SERVICE_NAME = CNTR.US.DELOITTE.COM)

    )

  )

3.   Sqlnet.ora

·       The "sqlnet.ora" file contains client side network configuration parameters.

·       It can be found in the "$ORACLE_HOME/network/admin" directory on the client.

·       This file will also be present on the server if client style connections are used on the server itself.

Ex:-

NAMES.DIRECTORY_PATH= (TNSNAMES, ONAMES, HOSTNAME)

NAMES.DEFAULT_DOMAIN = WORLD