Configure the Firewalld Ports

Description

Configure the firewalld ports to allow approved services to have access to the system. To configure firewalld to open ports, run the following command:

firewall-cmd --permanent --add-port=port_number/tcp

To configure firewalld to allow access for pre-defined services, run the following command:

firewall-cmd --permanent --add-service=service_name

Rationale

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 on information systems.

Operating systems 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., VPN and IPS); however, doing so increases risk over limiting the services provided by one component.

To support the requirements and principles of least functionality, the operating system 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.