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How to Disable or Stop Firewall on CentOS7

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disable firewall on centos

Firewalls are often the first line of network security. That’s why effective firewall management is essential to protect servers from unauthorized access and malicious activity.

Whether you’re configuring a new application that requires open ports or setting up a testing environment, understanding how to manage your firewall can significantly enhance your system’s accessibility and performance. 

White working with servers, there are certain scenarios where temporarily disabling a firewall might be a requirement. This includes troubleshooting software conflicts or to use specific network services. 

In this tutorial, we will discuss how to disable the firewall in CentOS 7. We will start with an overview of the idea of firewall and then go into the details of disabling the firewall on a CentOS7 server. 

Table Of Contents

  1. What is Firewall?
  2. Types of Firewall
    1. Hardware Firewall
    2. Software Firewall
    3. Packet Filtering Firewall
    4. Stateful Inspection Firewall
    5. Application-Level Gateway (Proxy Firewall)
    6. Next-Generation Firewall (NGFW)
  3. Why Disable Firewall on CentOS?
    1. Troubleshoot Software Conflicts
    2. Use Specific Network Services
  4. The Prerequisites to Disabling Firewall on CentOS 7
  5. How to Disable Firewall in CentOS 7?
    1. Step #1: Verify the Current firewall Status
    2. Step #2: Disable firewall
  6. Conclusion
  7. FAQs

What is Firewall?

A firewall is a digital security system component that acts as a barrier between your system network and the Internet. It monitors incoming and outgoing traffic based on a set of predefined security rules. Essentially, the firewall acts as the guard at the entrance to your network that only allows authorized traffic to pass through.

Types of Firewall

Firewalls are classified into two main categories based on their deployment configuration: hardware and software firewalls. 

Hardware Firewall

A hardware firewall is a physical device placed between the network and the internet. These devices offer a strong first layer of defense by filtering incoming and outgoing traffic based on a set of security rules.

Hardware firewalls are typically used by businesses and organizations that need a high level of security.

Software Firewall

A software firewall is a program installed on the system or other device. 

These firewalls monitor incoming and outgoing traffic on the device and block any traffic that does not meet the security rules. Software firewalls are typically less expensive than hardware firewalls, and may not be powerful. Most operating systems, like Windows and macOS, have a built-in software firewall.

In addition to these two major categories, firewalls can also be divided into the following operation-based categories.

Packet Filtering Firewall

A packet-filtering firewall is the most basic type of firewall. It examines individual data packets traveling across a network. 

The firewall compares the packet to a set of rules and allows or blocks it based on those rules. Despite their efficiency, packet-filtering firewalls cannot detect sophisticated attacks.

Stateful Inspection Firewall

A stateful inspection firewall is a more advanced firewall that keeps track of the state of network connections. As a result, these firewalls can make more informed decisions in traffic management. 

Application-Level Gateway (Proxy Firewall)

A proxy firewall, also known as an application-level gateway, examines traffic at the application layer of the OSI model. It inspects the actual content of the data packets, not just the header information. Proxy firewalls are very effective at blocking attacks, but can also slow down network performance.

Next-Generation Firewall (NGFW)

A next-generation firewall (NGFW) is a type of firewall that combines the features of traditional firewalls with additional security features, such as intrusion detection and prevention systems (IDS/IPS), deep packet inspection (DPI), and application control. It provides comprehensive protection against a wide range of threats.

Why Disable Firewall on CentOS?

We do not recommend disabling firewalls as they act as a crucial security barrier, and disabling them exposes your system to significant risks. 

However, there are a few niche situations where temporarily disabling a firewall might be considered:

Troubleshoot Software Conflicts

If the firewall is blocking a program, temporarily disabling the firewall would help you diagnose the problem. 

Use Specific Network Services

In rare cases, a firewall might block a legitimate application or service you need to use for a specific task. Therefore temporarily disabling the firewall would help you utilize the network service. 

Now that you have a basic understanding of firewalls and their types and the reasons to temporarily disable them, let us understand how to disable firewalls in CentOS 7. 

However, before that, let us take a quick look at the prerequisites. 

The Prerequisites to Disabling Firewall on CentOS 7

  • A CentOS 7 System
  • A user account with sudo or administrative privilege.
  • Access to the terminal/command line.

How to Disable Firewall in CentOS 7?

We do not recommend disabling the firewall. 

You should only disable the firewall as a temporary measure for troubleshooting purposes, and re-enable it as soon as possible.

Now let us look at how to disable the firewall in CentOS 7.

Step #1: Verify the Current firewall Status

In CentOS 7, firewalld is the default application that manages the firewall and all the CentOS 7 installations have the firewall enabled by default.

To determine the status of the firewall, execute the following command in the terminal:

# systemctl status firewalld

If the firewall is active, the output displays an active status.

systemctl status firewalld

Step #2: Disable firewall

The firewall can be disabled permanently or temporarily. Even though we recommend temporarily disabling the firewall, we will present both options.

Temporarily Disable the firewall on CentOS 7

To temporarily deactivate the default firewall manager on CentOS 7, execute the following command:

# systemctl stop firewalld

You won’t receive a confirmation message. Therefore, to verify if the firewall has been disabled successfully, check its status by executing this command in the terminal:

# systemctl status firewalld

The output displays if the firewall is active or disabled. 

Note: the systemctl stop firewalld command disables the service temporarily. The firewall service will reactivate once the current session ends and the system reboots.

systemctl status firewalld 2

Permanently Disable the firewall on CentOS 7

Note: We do not recommend permanently disabling the firewall as it can compromise the security of your server. However, there may be some specific and controlled scenarios where the idea could be considered, usually within a secure, isolated, and closely monitored environment. 

Start by stopping the firewall temporarily with the following command:

# systemctl stop firewalld

Next, check the status of the firewall settings to confirm if the service has been halted.

# systemctl status firewalld

Once the output confirms the service is inactive, execute the second phase of the process where we disable the firewall so that it doesn’t start on the next system reboot.

We recommend you execute the following command in the terminal: 

# systemctl turn off firewalld

sudo systemctl turn off firewalld

You have now successfully stopped and disabled the firewall service on your CentOS 7 server. 

Even when the CentOS 7 firewall service is disabled, other running processes can still activate it. This defeats the purpose of disabling the firewall in the first place. In order to prevent this, the firewall should be masked from other system services.

Execute the following command to hide the firewall from the active systems:

# systemctl mask --now firewalld

This command creates a symbolic link (symlink) for the firewall service to /dev/null, effectively turning it off. 

The expected output from this command is:

Created symlink from /etc/systemd/system/firewalld.service to /dev/null.

Conclusion

Turning off the firewall on CentOS 7 can be crucial for specific administrative tasks and application setups that require direct access to the system without the hindrance of security barriers. 

This guide has provided clear instructions on how to safely disable or stop the firewall, allowing for enhanced flexibility and control over your network’s configurations. It’s important to remember that while having the firewall disabled might be necessary in some scenarios, always consider the security implications and re-enable it as soon as possible to protect your system from potential threats.

FAQs

Q. What is the default firewall tool on CentOS 7?

CentOS 7 employs FirewallD as its standard firewall tool. It manages network traffic and enforces firewall rules on incoming and outgoing connections.

Q. How do I verify the current status of the firewall?

To check the current status of the firewall, use the firewall-cmd—-state command. This will notify whether the firewall is active or not.

Q. What permissions are required to modify firewall settings on CentOS 7?

To modify firewall settings, including turning it off, you must be a user with sudo privileges or the root user. This guarantees that only authorized individuals can modify security settings.

Q. How do I stop the firewall on a CentOS 7 server?

To temporarily halt the firewall on CentOS 7, execute the command sudo systemctl stop firewalld. This will cease all firewall rules until the next reboot.

Q. How can I permanently turn off the firewall on CentOS 7?

For a permanent solution, turn off the firewall. Once done execute the command sudo systemctl turn off firewalld to prevent the firewall from activating once the system reboots. In addition, masking the service with sudo systemctl mask –now firewalld will prevent other services from re-enabling it.

Q. Are there different trust levels or zones managed by FirewallD?

Yes, FirewallD manages different zones that represent trust levels for network connections. These trust levels help determine how strict the firewall rules should be depending on the network’s security requirements.

Q. How does Firewalld handle IPv6 firewall settings?

Firewalld supports both IPv4 and IPv6 firewall settings. You can manage and configure firewall rules for IPv6 using the same firewall-cmd command as with IPv4.

Q. What should I consider when managing firewall settings on dedicated servers?

When managing firewall settings on dedicated servers, consider the external network environments and the security requirements. Ensure that only necessary network connections are allowed and that firewall rules are appropriately stringent to protect against external threats.

Q. Can I configure firewall rules on CentOS desktop systems?

Yes, the same commands and methods apply to desktop systems running CentOS. Ensure you have the necessary administrative privileges to change the firewall settings.

Q. Where can I find more detailed CentOS and Red Hat firewall configuration tutorials?

For more detailed information, refer to tutorials such as the CentOS / Red Hat Iptables Firewall Configuration Tutorial or seek out resources specific to Linux firewall configurations that cover advanced settings and scenarios.

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