[Futcher91] D.A. Futcher, R.L. Sharp, and B.K. Yasaki, Building a Multi-Level Secure TCP/IP, Proceedings of the 14th National Computer Security Conference (October, 1991):78--87. [Discusses shortcomings of current implementations, including that most TCP/IPs are implemented in the kernel and have access to all kernel data structures, no labeling provisions for sensitivity exist, data of different sensitivity levels is buffered in the kernel, and datagram routing may violate security policy.]