cat listener.ora

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /opt/home/oracle/product/10.2.0/db_1)
      (PROGRAM = extproc)
     )
     SID_DESC =
      (GLOBAL_DBNAME = RBT)  #if you db name is RBT
      (ORACLE_HOME = /opt/home/oracle/product/10.2.0/db_1)
      (SID_NAME = RBT)
     )
   )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = node.internal)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )