Learn how to – Install and use Firewalld on Ubuntu 22.04|20.04|18.04

Learn how to – Install and use Firewalld on Ubuntu 22.04|20.04|18.04.

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.

In this guide, I’ll show you the basic usage of Firewalld on Ubuntu 22.04|20.04|18.04 Linux distributions. The default firewall system for Ubuntu is ufw but you can install and use Firewalld if you prefer. Firewalld works fine for me since I’m a heavy CentOS 7 user.

Step 1 – Install Firewalld on Ubuntu 22.04|20.04|18.04

Install Firewalld on Ubuntu22.04|20.04|18.04 by running the commands:

sudo apt update
sudo apt install firewalld

By default, the service should be started, if not running, start and enable it to start on boot:

sudo systemctl enable firewalld
sudo systemctl start firewalld

Confirm that the service is running:

$ sudo firewall-cmd --state
running

If you have ufw enabled, disable it to make firewalld your default firewall

sudo ufw disable

Step 2: Using Firewalld on Ubuntu22.04|20.04|18.04

Now that the package has been installed and firewalld service started, let’ look at few usage examples

See below examples for the basic usage of firewalld.

1. List all firewall rules configured

$ sudo firewall-cmd --list-all
public
  target: default
  icmp-block-inversion: no
  interfaces: 
  sources: 
  services: ssh dhcpv6-client
  ports: 
  protocols: 
  masquerade: no
  forward-ports: 
  source-ports: 
  icmp-blocks: 
  rich rules:

ssh and dhcpv6-client services are enabled by default when you start firewalld service.

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

To see all active services run the following command:

sudo firewall-cmd --get-services

3. Enable http service

In this example we enable http service.

sudo firewall-cmd --add-service=http --permanent

The --permanent option means persist rules against server reboots.

4. Enable both http and https on a single line

Here is an example on enabling both http and https services:

sudo firewall-cmd --permanent --add-service={http,https} --permanent

5. Enable TCP port 7070

Enable TCP port 7070

sudo firewall-cmd --add-port=7070/tcp --permanent

6. Enable UDP port 514

How to enable UDP port 514

sudo firewall-cmd --add-port=514/udp --permanent

7. Create a new zone

Creation of a new zone named myzone

sudo firewall-cmd --new-zone=myzone --permanent

8. Enable service on a specific zone

Let’s enable a service on the zone created:

sudo firewall-cmd --zone=myzone --add-port=4567/tcp --permanent

9. Set default zone

Set created zone as default

sudo firewall-cmd --set-default-zone=public --permanent

10. Add an interface to a zone

Adding an interface to a zone:

sudo firewall-cmd --get-zone-of-interface=eth0 --permanent
sudo firewall-cmd --zone=<zone> --add-interface=eth0 --permanent

11. Allow access to a port from specific subnet/IP

How to allow specified subnet access to service or port:

# Allow access to ssh from 192.168.0.12 sing IP address
sudo firewall-cmd --add-rich-rule 'rule family="ipv4" service name="ssh" 
source address="192.168.0.12/32" accept' --permanent

# Allow access to ssh from 10.1.1.0/24 network
sudo firewall-cmd --add-rich-rule 'rule family="ipv4" service name="ssh" 
source address="10.1.1.0/24" accept' --permanent

12. List rich rules

List rich rules on the system

sudo firewall-cmd --list-rich-rules

13. Configure Port forwarding

Enable port forwarding:

# Enable masquerading
sudo firewall-cmd --add-masquerade --permanent

# Port forward to a different port within same server ( 22 > 2022)
sudo firewall-cmd --add-forward-port=port=22:proto=tcp:toport=2022 --permanent

# Port forward to same port on a different server (local:22 > 192.168.2.10:22)
sudo firewall-cmd --add-forward-port=port=22:proto=tcp:toaddr=192.168.2.10 --permanent

# Port forward to different port on a different server (local:7071 > 10.50.142.37:9071)
sudo firewall-cmd --add-forward-port=port=7071:proto=tcp:toport=9071:toaddr=10.50.142.37 --permanent

14. Removing port/service

Replace --add with –-remove

For further reading, refer to the Official Firewalld Documentation