Can passive mode use only one port?

[Ulysess Lee 李宇光]

Hi all,
    For firewall reason, I need to use the lowest possible number of ports, I 
tested:

    DataConnectionConfigurationFactory dataconnConf = new 
DataConnectionConfigurationFactory();
    dataconnConf.setPassivePorts("2222");

    to set passive mode use only one port, but I found it dose not work well 
with 10 concurrent users uploading,
    Can passive mode use only one port for data connection?