The Cyber Essentials certification scheme is a UK government-backed initiative that aims to help organizations protect themselves against common cyber threats. The scheme includes five technical controls, one of which is firewalls.

The Cyber Essentials control for firewalls requires organizations to implement a firewall to protect their systems and networks from unauthorized access and cyber-attacks. Specifically, the control requires organizations to:

1. Implement a firewall: Organizations should implement a firewall to control inbound and outbound traffic and prevent unauthorized access to their systems and networks.
2. Configure firewall rules: Firewall rules should be configured to only allow authorized traffic and to block unauthorized traffic. This includes only allowing inbound traffic on necessary ports, and only allowing outbound traffic to authorized destinations.
3. Regularly update firewall rules: Organizations should regularly review and update firewall rules to reflect the latest security risks and threats, as well as changes to their systems and networks.
4. Monitor firewall logs: Firewall logs should be regularly monitored to detect and respond to any unauthorized access attempts or other security incidents.
5. Use next-gen Firewall if possible: Organizations should consider using Next-Generation Firewall (NGFW) which have additional features like intrusion prevention, threat intelligence, application control, and more to provide a more robust protection to their systems.

By implementing these controls and practices, organizations can meet the Cyber Essentials control for firewalls and protect their systems and networks from unauthorized access and cyber-attacks. It's important to keep in mind that the Cyber Essentials is a basic certification that only covers common cyber threats, and organizations should consider other measures as well to achieve a more robust protection.