As the world turns its focus to the protection of our societies underlying infrastructures, the realization that the world runs on computer networks has taken hold. The number of new technologies and solutions to better protect and secure the networks that allow our world to operate, is rapidly growing. As these technologies and solutions emerge, there is a need to study, test and further develop them. The Internet-Scale Event and Attack Generation Environment (ISEAGE) laboratory provides a unique environment for this studying, testing and development of networking protocols, technologies, and solutions. However, the ISEAGE laboratory also has a number of its own unique needs. Among which is the need for a methodology and framework for the generation and management of simulated network traffic. Network Traffic Simulator (NTS) provides a framework and baseline for a variety of network traffic simulation tools laid out in the ISEAGE Implementation Plan. Running from a single networked machine, the NTS tool can simulate an entire network of legitimate computer traffic in a variety of protocols and circumstances. Moreover, NTS provides the ability to script network traffic into easily readable and executable network conversations. This thesis provides the requirements, design, and implementation details of Network Traffic Simulator. This traffic simulation utility provides the ISEAGE laboratory with a unique solution for the insertion and management of networked packets and conversations, as well as a framework for the development of a suite of other network traffic insertion tools.