Ubuntu OS must have an application firewall installed to control remote access methods.

Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and make remote user access management difficult at best.

Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Ubuntu OS functionality (e.g., RDP) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets).

Verify the Uncomplicated Firewall (ufw) is installed by using the following command:

     $ dpkg -l | grep ufw 
     ii     ufw     0.36.1-4ubuntu0.1     all     program for managing a Netfilter firewall 

If the "ufw" package is not installed, ask the system administrator if another application firewall is installed.

If no application firewall is installed, this is a finding.

Install the ufw by using the following command:

     $ sudo apt-get install ufw