What command is used to set a firewall to active in a Linux system?

The command used to set a firewall to active in a Linux system is associated with the management of firewall services. Often, in modern Linux distributions that utilize firewalld, the correct command is to use firewall-cmd with the --set-active-zone option or similar, but in the context of the options provided, starting the firewall service aligns closely with administrative practices.

While "start" seems like a reasonable choice, typically, you might control services through system managers like systemd, wherein systemctl start firewalld would initiate the service. However, "runtime" signifies the operational status of the firewall, which reflects whether the service is actively managing rules and filtering traffic.

In context, activating or enabling a firewall is often distinguished by the term "runtime," which in this context relates to how the firewall operates immediately with the rules currently loaded without needing to reboot or reload configurations. This emphasizes the dynamic nature of firewall rules and their immediate application which is crucial in maintaining an active and responsive security configuration in a Linux environment.