UDP

Package upnp provides a simple and opinionated interface to UPnP-enabled routers, allowing users to forward ports and discover their external IP address. Specific quirks: - When attempting to discover UPnP-enabled routers on the network, only the first such router is returned. If you have multiple routers, this may cause some trouble. But why would you do that? - Forwarded ports are always symmetric, e.g. the router's port 9980 will be mapped to the client's port 9980. This will be unacceptable for some purposes, but too bad. Symmetric mappings are the desired behavior 99% of the time, and they save a function argument. - TCP and UDP protocols are forwarded together. - Ports are forwarded permanently. Some other implementations lease a port mapping for a set duration, and then renew it periodically. This is nice, because it means mappings won't stick around after they've served their purpose. Unfortunately, some routers only support permanent mappings, so this package has chosen to support the lowest common denominator. To un-forward a port, you must use the Clear function (or do it manually). Once you've discovered your router, you can retrieve its address by calling its Location method. This address can be supplied to Load to connect to the router directly, which is much faster than calling Discover.

Package udpchan provides a thin channel wrapper around UDP connections.