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The 15 Most Important firewall-cmd Commands in Linux

In computing, a good firewall system can prevent any unauthorized access to the network security systems. Businesses and organizations invest a good amount of money in their cybersecurity infrastructure, depending on how crucial their business is.

In this article, we will see the fundamentals of a new firewall service introduced in CentOS 7 named FirewallD. It comes with an extremely powerful filtering system called Netfilter, which is built right into the kernel module to check every packet that travels across to the system. This means it can inspect, modify, reject or drop on any of the network packets like incoming, outgoing or forwarded programmatically before reaching the destination. In Centos-7 onwards firewall became a default tool to manage the host-based firewall service. The daemon of the firewalld is installed from the firewalld package and it will be available on all the base installations of the OS but not on the minimal installation.