running ftpd in a jail

[Hiren]

greetings 

i am setting up a ftp server.
since i prefer setting all services within jails, i thought i would
setup ftpd within a jail.
i was basically NATing the required ports to the jails.
i realized that ftpd in passive mode was almost impossible to NAT since
it uses a wide range of ports.
i then resorted to NATing ports 20 and 21 and using active mode for my
server.
i wanted to know which mode is more secure and how would i go about
setting up ftpd within a jail in passive mode.

i would appreciate advice and comments

thanks

Hiren Patel