87-01-30 Secure External Network Communications

Large organizations must be able to communicate with external suppliers, partners, and customers. Implementation of bidirectional E-mail and file transfers, however, may pose a significant security threat to the organization's internal systems. This article describes a network architecture for securing external communications that has been successfully implemented at Lockheed Missiles and Space Co. This architecture employs security mechanisms, referred to as a firewall, which protects internal trusted systems from external networks. The firewall model is supported by a thorough set of technical and administrative support policies and procedures.