| In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols/services on information systems.
Applications are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., email and web services); however, doing so increases risk over limiting the services provided by any one component.
To support the requirements and principles of least functionality, the application must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues.
Database Management Systems using ports, protocols, and services deemed unsafe are open to attack through those ports, protocols, and services. This can allow unauthorized access to the database and through the database to other components of the information system.
A Postgres database cluster (i.e., instance) listens for connections on a single TCP port. The default port for an EDB Postgres Advanced Server cluster is 5444; however, the port number that is used is configurable via the Postgres "port" parameter. A database restart is required to apply a change to the port parameter. Also by default, a Postgres cluster will listen for connections on all interfaces on the host. The "listen_addresses" parameter can be used to configure specific interfaces on the host to listen for connections. The default value of "*" indicates all interfaces are used. To listen only on specific interfaces, the listen_addresses parameter is configured with a comma-separated list of host names and/or numeric IP addresses corresponding to the interfaces that should be used. As with the port parameter, changes to the listen_addresses parameter requires a cluster restart to take effect. |