How to use Firewalld service to enable/disable port in Linux machine

Firewalld is Linux firewall management tool with support for IPv4, IPv6, Ethernet bridges and IPSet firewall settings.

It acts as a front-end to Linux kernel’s netfilter framework.

Firewalld is a default firewall management software on RHEL 7 family.

How to install firewalld

Ubuntu

sudo apt install firewalld -y

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Check the status of firewalld service

sudo systemctl status firewalld

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To list all firewall rules configured

firewall-cmd --list-all

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By default all ports are blocked when firewall is enabled except ssh and dhcpv6-client services.

To enable TCP port

Lets enable port 8080

sudo firewall-cmd --add-port=8080/tcp --permanent
sudo firewall-cmd --reload
sudo firewall-cmd --list-all

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Get a list of all services that can be enabled using a service name

sudo firewall-cmd --get-services

Enable service port using service name

Lets enable Enable http service

sudo firewall-cmd --add-service=http --permanent
sudo firewall-cmd --reload
sudo firewall-cmd --list-all

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To disable enabled TCP port

Lets disable port 8080

sudo firewall-cmd --remove-port=8080/tcp --permanent
sudo firewall-cmd --reload
sudo firewall-cmd --list-all

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To uninstall firewalld

sudo apt autoremove firewalld -y

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Reference