Safeguarding Your Network with Firewall-cmd: A Step-by-Step Guide on Listing and Assessing Firewall Rules

    skycentral.co.uk | Safeguarding Your Network with Firewall-cmd: A Step-by-Step Guide on Listing and Assessing Firewall Rules


    In today’s digital age, ensuring the security and integrity of your network is of utmost importance. With cyber threats and attacks becoming more sophisticated every day, it is crucial to have a robust firewall system in place. Among the various tools available, firewall-cmd is a powerful utility that allows you to configure and manage firewall rules on your Linux system. In this step-by-step guide, we will explore how to list and assess firewall rules using firewall-cmd, helping you safeguard your network effectively.

    Understanding Firewall Rules

    Before we dive into the details, let’s first understand what firewall rules are. Firewall rules essentially act as a set of instructions that dictate how incoming and outgoing network traffic should be handled. These rules determine which connections should be allowed or denied, acting as a barrier between your network and potential threats.

    Listing Firewall Rules with firewall-cmd

    To get started, you need to have firewall-cmd installed on your Linux system. Once installed, open a terminal and let’s begin by listing the current firewall rules using the following command:

    $ firewall-cmd –list-all

    This command will display a comprehensive list of all the firewall rules currently in effect. By default, firewall-cmd uses the firewalld service, which is a dynamically managed firewall solution. The output will provide you with information such as the default zone, active zones, services, ports, and custom rules that have been configured.

    Assessing Firewall Rules

    Now that you have a list of the existing firewall rules, it’s essential to thoroughly assess them to ensure they align with your network security requirements. Some key points to consider during the assessment are:

    1. Default Zone: Check the default zone assigned to your network. This zone determines the level of trust assigned to different connections. Make sure that the default zone is appropriate for your network’s intended use.

    2. Active Zones: Examine the active zones and verify that the assigned rules are suitable for each specific zone. Often, networks have multiple active zones, such as “internal” and “public.” Each zone should have the necessary rules defined to protect your network based on its respective security needs.

    3. Services and Ports: Review the services and ports that are allowed or denied by the firewall. Ensure that only the necessary services and ports are open to incoming connections. Unwanted services and ports should be closed.

    4. Custom Rules: Evaluate any custom rules that have been configured. These rules might define specific network traffic restrictions or exceptions based on your network requirements. Make sure they are still relevant and serving their intended purpose.

    5. Logging Rules: Determine if logging rules have been implemented to monitor network traffic. Logging can aid in identifying and analyzing any potential security breaches. If logging is absent or insufficient, consider adding logging rules to enhance your network’s security.

    Taking Action

    After assessing the existing firewall rules, you might identify areas that need improvement or adjustment. Here are some actions you can take to safeguard your network effectively:

    1. Modifying Existing Rules: If you find any rules that require modification, such as opening a specific port or service, you can use the `–add-port` or `–add-service` options to make the necessary changes. For example, to allow incoming connections on port 80, you can use the following command:
    $ firewall-cmd –zone=public –add-port=80/tcp –permanent
    Remember to reload the firewall configuration after any modifications by running:
    $ firewall-cmd –reload

    2. Adding New Rules: In some cases, you might need to add entirely new rules to cater to specific requirements. For example, if you want to restrict access from a particular IP address, you can use the `–add-rich-rule` option along with the desired conditions. Once the new rule is added, remember to reload the firewall configuration.

    3. Removing Unnecessary Rules: If you come across any obsolete or redundant rules, it’s important to remove them promptly. You can use the `–remove-port`, `–remove-service`, or `–remove-rich-rule` options to eliminate these unnecessary rules. Again, don’t forget to reload the firewall configuration after removal.

    4. Regular Review and Update: Network security is an ongoing process, and it is crucial to regularly review and update your firewall rules. Cyber threats are constantly evolving, and adapting your firewall rules to tackle new risks is essential. Perform periodic assessments, apply any necessary changes, and keep your firewall configuration up to date.


    Protecting your network from potential cyber threats is a vital aspect of maintaining a secure digital environment. By utilizing firewall-cmd and following this step-by-step guide, you can effectively list and assess your firewall rules. Thoroughly review your existing rules and make any necessary adjustments to ensure the highest level of network security. Remember, regular monitoring and updating of your firewall rules are essential to keep up with the ever-changing threat landscape and safeguard your network effectively.