revision 44b9a48a151c7791ee983cd58dcfd80c7288fe20
$ gssdp-discover -i wlan0 --timeout=3 --target=urn:schemas-upnp-org:device:MediaRenderer:1
https://stackoverflow.com/questions/18363833/how-can-i-list-upnp-server-renderer-in-command-line-console-mode-on-linux