A Protocol for communicating between Oracle databases and applications over networks.
It supports, IP Protocol Stack, IPv6, and TLS/SSL.
It can be used for:
- Name resolution
- Connection management
- Load balancing
- Security
By default the listener listens on TCP Port 1521, which can be changed by configuration.
Configurations
Configuration files are found in $ORACLE_HOME/network/admin:
tnsnames.ora: contain files necessary for Clients to connect to a service. An entry consist of a service name, network location of the service, and the service/database name that clients should use when connecting.listener.ora: contain server-side configurations that define the properties and parameters of the listener process, which is responsible for receiving incoming client requests and forwarding them to appropriate Oracle database instance.