The Oracle Database Listener is the database server software component that manages the network traffic between the Oracle Database and the client. The Oracle Database Listener listens on a specific network port (default 1521) and forwards network connections to the Database. The Listener is comprised of two binaries: (1) tnslsnr which is the Listener itself and (2) the Listener Control Utility (lsnrctl) which is used to administer the Listener on the server or remotely.