For more information, refer to: https://help.ubuntu.com/community/Gufw
Gufw is a firewall powered by UFW (Uncomplicated Firewall). For an overview of firewalls, please see Firewall.
In order to install Gufw, you must have the Universe repository enabled. To install, use Synaptic, or run from Terminal:
sudo apt-get install gufw
To access GUFW, go to System->Administration->Firewall configuration.
By default, the firewall is disabled.
To enable the firewall, simply check the Enabled button and the default will be set to Deny for incoming traffic and Allow for outgoing traffic.
To configure the firewall, we add rules. Simply click the Add button and a new window will pop up. For details about this implementation, see the UFW page. Rules can be configured for TCP and UDP ports, and UFW has some preconfigured programs/services to make setting up rules for them easy.
The available options for rules are Allow, Deny, Reject, and Limit:
Allow: The system will allow entry traffic for a port.
Deny: The system will deny entry traffic to a port.
Reject: The system will deny entry traffic to a port and will inform the requesting for connection system that it has been rejected.
Limit: The system will deny connections if an IP address has attempted to initiate 6 or more connections in the last 30 seconds.
The Preconfigured tab gives us some options for controlling firewall options for common programs and services.
You have several categories and subcategories. You can filter by name/description/ports too.
Not all program configurations are available in Gufw, but we can still add rules for them using the Simple tab.
Again, we’ll use the SSH example – let’s just pretend for a moment that there isn’t a preconfigured option for it. To enable it in the Simple tab, select “Allow”, “TCP”, “22” and click Add.
Sometimes we want to configure access based on a specific IP, so we use the Advanced tab, for example to add Port Forwarding.
Enable IP forwarding
Gufw 14.10 or higher.
How use set it
To routing policy and rules, you must setup IP forwarding in the system:
Uncomment these 3 lines in the file /etc/ufw/sysctl.conf:
Edit the file /etc/default/ufw with DEFAULT_FORWARD_POLICY=”ACCEPT”
Reload the firewall:
sudo ufw reload
Open Gufw, you’ll see a new “Routed” option (with an arrow around the shield) and you can forward any rule from the Update window or Advanced Tab in Add window.