"TCMPortMapper.framework" is a clean and nice Objective-C API to provide knowledge about and improve the reachability of your machine from the big bad internet. "Port Map.app" is a nice standalone sample app using the framework to display reachability and enable setup of Port Mappings if your router allows for it.

[mirror] A GTK application to access the parameters of the router exposed via UPnP-IGD. Access to network speed, external IP and model name. It can manage port forwarding through a simple GUI interface.

Forked to improve the UPnP IGD & PCP/NAT-PMP server and IGD client implementation