How many ports should i open?
All Clients first contact the Server on port 2774, or 21, or whatever you have defined as your main port number. The Server then tells the Client to call back on a different port number to send its data. Each client that calls in simultaneously will get a different port number called the “Data Port,” and may attempt to use as many as five ports, depending on bandwidth availability. That way the Server can handle many simultaneous users. You can tell the Server to assign its Data Ports in a specific range using the TOOLS > PROPERTIES > RBS PREFERENCES screen of the RBS Manager. For maximum speed under most conditions the “USER-DEFINED PASSIVE MODE DATA PORT RANGE” needs to have a range that includes 5 ports per simultaneous user, and 100 minimum. After you restrict the port range you can open only that range of ports through your firewall, if necessary. The software will not allow you to assign ports in a range below port 1024 to avoid conflicting with other known hardware and software
