NASA NTRS2006
This paper describes a strong perimeter control system for a general purpose processing system, with the perimeter control system taking significant steps to address usability issues, thus mitigating the tension between strong perimeter protection and usability. A secure front end enforces two-factor authentication for all interactive access to an enclave that contains a large supercomputer and various associated systems, with each requiring their own authentication. Usability is addressed through a design in which the user has to perform two-factor authentication at the secure front end in order to gain access to the enclave, while an agent transparently performs public key authentication as needed to authenticate to specific systems within the enclave. The paper then describes a proxy system that allows users to transfer files into the enclave under script control, when the user is not present to perform two-factor authentication. This uses a pre-authorization approach based on public key technology, which is still strongly tied to both two-factor authentication and strict control over where files can be transferred on the target system. Finally the paper describes an approach to support network applications and systems such as grids or parallel file transfer protocols that require the use of many ports through the perimeter. The paper describes a least privilege approach that dynamically opens ports on a host-specific, if-authorized, as-needed, just-in-time basis.