How To Reset Linux Firewall

Resetting a Linux firewall depends on which firewall tool you are using. This guide covers the four most common options—UFW, Firewalld, iptables, and nftables—with clear steps to restore default settings.

UFW (Uncomplicated Firewall)

• Reset UFW to Default:

  sudo ufw reset

  Removes all rules and disables UFW.
• Re-enable UFW:

  sudo ufw enable

• Optional: Set Default Policies:

  sudo ufw default deny incoming
  sudo ufw default allow outgoing

Firewalld

• Fully Reset Firewalld (Delete All Zones and Reload):

  sudo systemctl stop firewalld
  sudo rm -rf /etc/firewalld
  sudo systemctl start firewalld

  This wipes all custom zones and rules. You will need to reconfigure zones afterward.

iptables

• Flush All Rules:

  sudo iptables -F
  sudo iptables -X
  sudo iptables -t nat -F
  sudo iptables -t nat -X
  sudo iptables -t mangle -F
  sudo iptables -t mangle -X

• Set Default Policies:

  sudo iptables -P INPUT ACCEPT
  sudo iptables -P FORWARD ACCEPT
  sudo iptables -P OUTPUT ACCEPT

• If Using iptables-persistent (Debian-based systems):

  sudo netfilter-persistent save
  sudo netfilter-persistent reload

• Alternative Save/Restore (Other distros):

  sudo iptables-save > /etc/sysconfig/iptables
  sudo ip6tables-save > /etc/sysconfig/ip6tables
  
  sudo iptables-restore < /etc/sysconfig/iptables
  sudo ip6tables-restore < /etc/sysconfig/ip6tables

• Or save using the service:

  sudo service iptables save

nftables

• Flush All Rules:

  sudo nft flush ruleset

• Optional: Load a Clean Configuration:

  sudo nft -f /etc/nftables.conf

  You can edit /etc/nftables.conf to define your default ruleset.

Note: Before resetting any firewall, you may want to back up your current rules.

By following these steps, you can safely reset Linux firewalls across different tools. This ensures a clean configuration and helps resolve issues caused by custom rules or misconfigurations.