An application firewall must be enabled on the system.

From Canonical Ubuntu 16.04 Security Technical Implementation Guide

Associated with: CCI-000366

SV-90485r2_rule An application firewall must be enabled on the system.

Vulnerability discussion

Firewalls protect computers from network attacks by blocking or limiting access to open network ports. Application firewalls limit which applications are allowed to communicate over the network.

Check content

Verify the Uncomplicated Firewall is enabled on the system by running the following command: # sudo systemctl is-enabled ufw enabled If the above command returns the status as "disabled", this is a finding. If the Uncomplicated Firewall is not installed, ask the System Administrator if another application firewall is installed. If no application firewall is installed this is a finding.

Fix text

Enable the Uncomplicated Firewall by using the following commands: # sudo systemctl start ufw # sudo systemctl enable ufw

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