The identity proxy provides access to a service an application cannot connect because of firewall by running on a machine that can connect to the service, and binding to a port that the application can connect to;
can also be a raw protocol analyzer.
Voodoo Exchange Networking Library is a D library that provides a simple API for creating streaming, peer-to-peer TCP connections between two clients, even if they are behind NATs or firewalls, by attempting multiple NAT traversal algorithms.