C2 Class C2, Controlled Access Protection, is described in DoD 5200.28-STD, Department of Defense Trusted Computer System Evaluation Criteria. Systems in this class make users individually accountable for their actions through login procedures, auditing of security-relevant events, and resource isolation. The certificate contains the security data and the seal. The cost of providing NISN services to a customer is billed to and debited from the customer's budget. There is neither access to nor from The Internet.
Communications are limited to a defined set of authorized addresses.
Examples of customers are officials in NASA Enterprises, Program Offices, the Associate Administrator for Headquarters Operations, and the Directors of NASA Centers and Field Installations. A combination of electronic data interchange and electronic funds transfer services aimed at enhancing commerce and business exchanges between organizations. A firewall is either the program or the computer it runs on, usually an Internet gateway server, that protects the resources of one network from users from other networks. Typically, an enterprise with an intranet that allows its workers access to the wider Internet will want a firewall to prevent outsiders from accessing its own private data resources. There are a number of firewall screening methods.