/usr/bin/mono-upnp-gtk is in mono-upnp-bin 0.1.2-2build1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3
#!/bin/sh exec mono "/usr/lib/mono-upnp/Mono.Upnp.GtkClient.exe" "$@"