dlnaproxy
dlnaproxy is meant to enable the use of a DLNA server (ex: MiniDLNA) past the local network boundary.
Use case
Let's say you're hosting a media library on a remote server. It might be because that remote server has more bandwith, more storage, or both.
It can also be your self-hosted NAS that you are trying to access from a remote location.
If you're able to connect to that server, either through a VPN or because the machine is routed directly on the Internet, dlnaproxy will attempt to connect to that server and if successful, it will announce it on your current LAN as if that server were there.
The diagram
Network boundary +------------------+
++ connect back | |
+----------++-------------------------+ you |
| || | |
| || +---^--------------+
+----v-----+ || +------------+ |
| Remote | || | +------------+
| DLNA <----++---+ dlnaproxy | broadcast
| Server | fetch info |
| | ++ | |
+----------+ || +------------+
||
||
++