IPTV MULTICASTING WITH ONLY ONE ROUTERBOARD

Good Morning,
This is my first post in this forum so i think i am at the right place.
I have read the wiki’s full exemple on PIM multicast but my situation is different and i have tried without succes to adapt.
i have one routerboard with 3 interfaces. ether1=WAN, ether2=HOTSPOT USERS and ether3=MULTICAST IPTV SERVER + OTHER SERVICES.
i would like authorized hotspot users to have acces to multicast iptv streams.
please help

I have managed to get working with my multicast trafic. i increased the TTL in mangle rules. my next probleme is to give acces to multicast packets only to logged in hotspot users