Functionality Minimization Analysis of Asterisk for Future Use in Secure Environments

Asterisk, the open-source PBX, supports various implementations of voice over Internet Protocol (VoIP), a popular alternative to public switched telephone networks (PSTN) that offers cost benefits and ease of management. The Monterey Security Architecture (MYSEA) is a distributed multilevel security (MLS) environment designed to provide secure, collaborative sharing of information. It does not currently support either real-time voice communications or voice mail. The purposes of this thesis are to determine high-level VoIP requirements and to build a minimized version of Asterisk that supports these requirements. This minimized version of Asterisk could then be ported to run within the MYSEA architecture. To achieve this goal, threats were enumerated and requirements were determined. Then the modules within Asterisk were minimized to eliminate unnecessary functionality while still supporting mechanisms required for voice communications and voice mail. Testing showed that voice calls could be placed and voice mail messages could be left and retrieved using the minimized Asterisk server. Asterisk's functionality was successfully minimized to meet the requirements determined through the VoIP analysis by reducing the number of modules used for the build. This work provides the groundwork for future implementations of VoIP and voice mail provided by Asterisk within MYSEA.