Installing Firewalld on CentOS 7

Firewalld is a dynamic firewall management tool available on CentOS 7. It provides a flexible way to configure and manage network firewalls using the concepts of zones and services. Firewalld allows you to define rules and policies to control the incoming and outgoing network traffic on your system.

Step 1: Checking Firewalld Availability

Before you start installing Firewalld, ensure that it is not already installed on your CentOS 7 system. Open a terminal and run the following command:

sudo yum list installed | grep firewalld

If the command returns any output, it means Firewalld is already installed. In that case, you can skip the installation process and proceed to configuring Firewalld.

Step 2: Installing Firewalld

To install Firewalld on CentOS 7, open a terminal and run the following commands:

sudo yum install firewalld

During the installation process, you may be prompted to accept the GPG key and confirm the installation. Press "y" to proceed.

Step 3: Enabling and Starting Firewalld

Once the installation is complete, enable Firewalld to start automatically at boot time by running the following command:

sudo systemctl enable firewalld

Next, start the Firewalld service using the following command:

sudo systemctl start firewalld

Step 4: Managing Firewalld

The Firewalld service provides a command-line tool called "firewall-cmd" to manage your firewall configuration. You can use this tool to add, remove, or modify firewall rules and settings.

To get started, you can display the default zone and active zones by running the following command:

sudo firewall-cmd --get-default-zone

sudo firewall-cmd --get-active-zones

You can view the predefined services and their associated ports using the following command:

sudo firewall-cmd --get-services

For more advanced configuration, refer to the official Firewalld documentation.

Congratulations! You have successfully installed Firewalld on CentOS 7. You can now start configuring the firewall rules and settings based on your needs.