Information
UncomplicatedFirewall (ufw) is a frontend for iptables. ufw provides a framework for managing netfilter, as well as a command-line and available graphical user interface for manipulating the firewall.
Graphical Uncomplicated Firewall (gufw) is a Graphical User Interface (GUI) for configuring ufw.
Note:
- When running ufw enable or starting ufw via its initscript, ufw will flush its chains. This is required so ufw can maintain a consistent state, but it may drop existing connections. ufw does support adding rules before enabling the firewall.
The ufw service must be enabled and running in order for ufw to protect the system
Solution
Run the following command to unmask the ufw daemon:
# systemctl unmask ufw.service
Run the following command to enable and start the ufw daemon:
# systemctl --now enable ufw.service
active
Run the following command to enable ufw:
# ufw enable
Impact:
Changing firewall settings while connected over network can result in being locked out of the system.