>GoToMyPC allows bidirectional communication between the client (any browser) and a host computer. The host computer can be behind a router and still be accessible to the client anywhere on the internet. This is done despite the fact that no router port-forwarding rules exist.
>
>As I understand it, the host computer stays in contact with GTMPC servers and when a client connects to GTMPC, the GTMPC servers pass along the connection info to the client to permit direct communication (or something to that effect).
>
>Let's say I wanted to allow bidirectional communication between an internet client and a host computer behind a router without having to configure port-forwarding on the router. What are the options to accomplish something like this?

Basically, the host computer behind the firewall is constantly (every few seconds) sending outbound requests (which are usually not blocked) to GTMPC, asking "Does a client want to connect to me?" Almost always the answer is "No" and the connection gets disconnected. If it's "Yes" then the connection is maintained. I don't know the details of how the client is added to that connection, or if once that's done the connection still requires the intermediary GTMPC server or if it gets "handed off" somehow.