FMS Streaming authenticated

I have one license of Flash media streaming.
I require authentication to send streaming media encoder.
I know this is only possible with interactive server. is true?

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which is the port for sending the live streaming?     Media Encoder  --->   FMS
which is the port for reading the stream?                FMS                 --->   html flvPlayer

If the ports are separated can use 2 different ip.

sorry for my english

Thanks