strugling with dlna / upnp port

[zygou]

Hello and thanks in advance for the help !

I'm wondering how does subsonic handle the dlna / UPnP port...
I've been struggling to understand it and so far here is what I can say about it.
I'll try to describe everything as much as I can so sorry if this post becomes quit long.

I'm running subsonic on a fedora server behind a freebox router (the box of some french internet provider)
I handled port forwarding manually, opened the port of the webapp on the server (4040 by default) and can access subsonic from outside my network perfectly.

but when i try to use some dlna device on my local network I can only find subsonic when I shutdown iptables and for some obvious reason this is not a long term option, you can imagine.

after looking for the listening port with nmap, I discovered what appears to be some randomly defined ports to handle dlna capabilities each time I restart subsonic...
to be precise, if I restart subsonic, look at the ports in use with nmap (35553 at the time and something completly different each time I restart subsonic), and open this port in iptable, then I'm able to partially use the dlna / upnp capabilities ...
but then I would have to modify my iptables each time I restart the server witch isn't an option neither.

I tried to look at the SUBSONIC_ARGS but haven't found anything to help me there.

So am I doing anything wrong here ? Is there a way to fix the port used by subsonic for dlna / upnp capabilities ?
(once again, just to be clear, I'm not talking about the port for the web application, no problem there ! I'm specifically talking about the ports used for DLNA / UPnP !)

I hope that I've been clear, any help would be appreciated, thanks !

UPDATE 1 :

After reviewing the last open source code I think I have my response.
it seems subsonic api implements some 4thline library for dlna support but with the default options. without any port explicitly specified the library set a random port.
So, to my knowledge, there is no way to determine the port that gonna be used for dlna by subsonic.
from what I see it looks quite simple to implement and would have happily done it myself, but since the code isn't open source anymore I guess I'll have to write a dirty script that looks for the port open by subsonic for dlna after subsonic is started and set the iptables to open it...

If anyone have other information on the subject this would still be appreciated