Iptables or Netfilter is the most popular and blazing fast open source CLI based Linux firewall. Many system administrators prefer to use it for their server protection as it plays the first line of defense of a Linux server protection. Both IPv4 and IPv6 are protected using iptables and ip6tables accordingly.

What firewall is used in Linux?

Iptables

Iptables/Netfilter is the most popular command line based firewall. It is the first line of defence of a Linux server security. Many system administrators use it for fine-tuning of their servers. It filters the packets in the network stack within the kernel itself.

How do I know if my firewall is running Linux?

To check firewall status use the ufw status command in the terminal. If the firewall is enabled, you will see the list of firewall rules and the status as active. If the firewall is disabled, you will get the message “Status: inactive”.