Firewalls shall be installed and activated on all the organization's networks.
Where appropriate, network integrity of the organization's critical systems shall be protected by incorporating network segmentation and segregation.
Where appropriate, network integrity of the organization's critical systems shall be protected by (1) Identifying, documenting, and controlling connections between system components. (2) Limiting external connections to the organization's critical systems.
The organization shall monitor and control connections and communications at the external boundary and at key internal boundaries within the organization's critical systems by implementing boundary protection devices where appropriate.
The organization shall implement, where feasible, authenticated proxy servers for defined communications traffic between the organization's critical systems and external networks.