How to open and close ports on RHEL 8 / CentOS 8 Linux

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Firewalld is a powerful and yet simple to use tool to manage a firewall on RHEL 8 / CentOS 8 Server or GNOME workstation. Firewalld allows to manage open or close ports using predefined services as well as open and close user custom ports.

In this tutorial you will learn:

  • How to open and close ports on RHEL 8 / CentOS 8 with Firewalld.
  • How to open and close services on RHEL 8 / CentOS 8.
  • How to reload firewall configuration.
  • How to list open ports or services.

Opening and Closing firewall ports on RHEL 8 / CentOS 8 using firewall-cmd command.

Opening and Closing firewall ports on RHEL 8 / CentOS 8 using firewall-cmd command.

Software Requirements and Conventions Used

Software Requirements and Linux Command Line Conventions
Category Requirements, Conventions or Software Version Used
System RHEL 8 / CentOS 8
Software firewall-cmd 0.6.3 or higher
Other Privileged access to your Linux system as root or via the sudo command.
Conventions # – requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
$ – requires given linux commands to be executed as a regular non-privileged user

How to open ports on RHEL 8 / CentOS 8 Linux step by step instructions

To open ports on RHEL 8 / CentOS 8 system is a rather simple procedure. Here is how it goes step by step:

  1. First, check for already opened ports or enabled systemd service. It might be that the port you are trying to open is already available in which case there is nothing to do: 
    # firewall-cmd --list-all
  2. Check whether the service you are trying to configure your firewall with is available as a preconfigured feature. The below command will list all ready to use services: 
    # firewall-cmd --get-services
  3. Obtain a list of zones you wish the port to be opened within: 
    # firewall-cmd --get-zones

    In most cases you are interested in the public zone which is the default firewall zone for all operations without explicitly providing zone name as an argument to the firewall-cmd command.

  4. Open port or service.

    If the service you wish to configure your firewall with is available as a preconfigured feature as retrieved in Step 2 use its name to open the port.

    For example let’s open HTTP service port for zone public:

    # firewall-cmd --zone=public --permanent --add-service=http

    In case the port you wish to open is not a part of the preconfigured services use the --add-port option. For example let’s open TCP port 8080 for zone public:

    # firewall-cmd --zone=public --permanent --add-port 8080/tcp
  5. Reload firewall settings. Once you have opened port or services make sure to reload the firewall: 
    # firewall-cmd --reload
  6. Confirm that port or service was opened successfully: 
    # firewall-cmd --list-all

How to close ports on RHEL 8 / CentOS 8 Linux step by step instructions

To open ports on RHEL 8 system is a rather simple procedure. Here is how it goes step by step:

  1. First check for already opened ports or services. Take a note of the zone, protocol as well as port or service you wish to close: 
    # firewall-cmd --list-all
  2. Close port or service. The below command will close the http service in the public zone: 
    # firewall-cmd --zone=public --permanent --remove-service http

    In case you wish to close a specific port use the --remove-port option. For example let’s close the TCP 8080 port:

    # firewall-cmd --zone=public --permanent --remove-port 8080
  3. Reload the firewall settings: 
    # firewall-cmd --reload
  4. Confirm that port or service was closed successfully: 
    # firewall-cmd --list-all

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