In order to be able to use P2P communication within flash apps, you need to have opened UDP ports in range 1024..65535. First, to connect stratus server, you need UDP ports 1935 and 10000..10100, then the communication between peers (Flash Players and AIR) goes through random UDP port in range 1024..65535. In detail:
UDP port 1935 and ports 10000+ are used by the Stratus servers. the UDP ports used on client computers could be any port from 1024..65535.
in order to just connect to the Stratus servers, you must be able to send and receive UDP packets with any UDP port on your client computer (source port for outgoing, destination port for incoming) and port 1935 and ports 10000+ on the Stratus server computers (destination port for outgoing, source port for incoming).
*just* connecting to Stratus isn’t useful, though, since all it can do is help you to connect directly to other clients running Flash Player or AIR. other client computers, just like your client computer, will be using a random UDP port in the range 1024..65535. therefore, in order to communicate P2P with other client computers using RTMFP, you must do one of the two following things:
1) allow all UDP with a source or destination port from 1024..65535.
2) have a “stateful firewall” that allows bidirectional UDP connections to and from any UDP ports in the range 1024 through 65535 inclusive as long as a first packet is sent outbound through the firewall. this is commonly called “allowing outbound UDP”. sending the first packet outbound through your firewall to allow return packets is commonly called “UDP hole punching”. searching on these terms should give you more information.
in general, a firewall that blocks UDP will block RTMFP communication.
Read more about PORT NUMBER of RTMFP.