Control the flow of CUI in accordance with approved authorizations.

By placing a firewall or other proxy between your network and the internet you prevent direct access to your systems from the internet. You can also prevent certain types of information from exiting your network. Employees must take special care when sending CUI over an external network. CUI should only be sent in encrypted form.

Use a firewall to control traffic entering and exiting your network. Configure firewall rules that limit traffic to specific ports. Instruct employees that they may only email, transfer, or share CUI in ecrypted form. They can do this using encrypted email (S/MIME), SFTP file transfer, or by sharing links to a secure cloud storage location.