The proliferation of networking technologies and applications bring new promises and challenges to the Internet. One such challenge is how to develop and manage a heterogeneous and colossal networking environment? Specifically, how to manage a network that consists of IPv4, RFC1918, IPv6, IPSec, mobile IP, and a variety of applications that use multiple IP transports, TCP, UDP, and Multicast? The Secure Transport Proxy Working Group (STP) is chartered to specify a generic mechanism to proxy IP transports in a secure manner. The protocol will evolve from the existing work done by the Authenticated Firewall Traversal Working Group (AFT). It will focus on transport proxy mechanisms that are secure, scalable, efficient and flexible. The protocol will be specifically designed for bi-directional establishment of TCP, UDP and Multicast proxy channels over a heterogeneous network environment, enabling application protocols to securely pass through firewalls.