Firewall Configuration

Configuring The Firewall

Start and enable the firewall

1. To start and enable the firewall use the commands below

systemctl start firewalld
systemctl enable firewalld

Get an overview

Default Zone

1. Find the default zone.  The default zone is usually public

firewall-cmd --get-default-zone

Display Allowed Services

1. Display the allowed services of the zone

firewall-cmd --list-service --zone=external

By default, "public" zone is applied with a NIC and dhcpv6-client and ssh are allowed.

Display Services Defined By Default

1. To list all service defined by default use the command below

firewall-cmd --get-services

It should give you an output similar to

Add/Remove services

1. Add or Remove allowed services.  The change will be back after rebooting the system. If you change settings permanently, add the "--permanent" option.

Add/Remove Ports

1. Add or remove allowed ports

Add/Remove Prohibited ICMP Types

1. Add or remove prohibited ICMP types