The listener.ora file is a configuration file that defines the Oracle services to which other systems can connect. By default, listener.ora resides in the following location:

The following is an example of the listener.ora file:

LISTENER =
  (ADDRESS_LIST =
        (ADDRESS = 
          (PROTOCOL = TCP)
          (Host = 127.0.0.1)
          (Port = 1521)
        )
  )
STARTUP_WAIT_TIME_LISTENER = 0
CONNECT_TIMEOUT_LISTENER = 10
TRACE_LEVEL_LISTENER = ADMIN
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = ccer)

    )

  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = host.symantecexample.com)
(PORT = 1521))
    )
  )