How To Set Up a Firewall Using FirewallD on CentOS 7

How To Set Up a Firewall Using FirewallD on CentOS 7

How To Set Up a Firewall Using FirewallD on CentOS 7

Introduction

Firewalls are an essential part of any secure network infrastructure. They help to prevent unauthorized access to your system and protect it from malicious attacks. In this tutorial, we will show you how to set up and configure a firewall on CentOS 7 using FirewallD.

Prerequisites

  • A server running CentOS 7
  • Root access or a user with sudo privileges

Step 1: Install FirewallD

The first step is to install FirewallD if it is not already installed on your system. To do this, run the following command:

sudo yum install firewalld

Step 2: Start and Enable FirewallD

Once FirewallD is installed, start and enable it so that it starts automatically at boot time:

sudo systemctl start firewalld sudo systemctl enable firewalld

Step 3: Check FirewallD Status

To check the status of FirewallD, run the following command:

sudo firewall-cmd --state

If FirewallD is running, you will see the following output:

running

Step 4: Configure FirewallD

Now that FirewallD is running, you can start configuring it to allow or deny traffic based on your requirements. The following are some examples of common FirewallD commands:

  • Allow incoming traffic on a specific port:
    • sudo firewall-cmd --zone=public --add-port=80/tcp --permanent
  • Deny incoming traffic on a specific port:
    • sudo firewall-cmd --zone=public --remove-port=22/tcp --permanent
  • List all available services:
    • sudo firewall-cmd --get-services

Remember to use the --permanent flag if you want to make the changes persistent across reboots.

Step 5: Reload FirewallD

After making any changes to the FirewallD configuration, you must reload the service to apply the changes:

sudo firewall-cmd --reload

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