SPAM: Passive ftp through firewall?

hello all... i set up my machine with the second nic and enabled masq all works great except! internet users can no longer ftp. the external card should accept ftp connections and allow passiv ports... Its fine it it doesnt goto my lan (2nd card) but i would like to re enable the passive ftp function... i looked thro yast and see only a ref to allow tftpd on the external... i know there is something i have overlooked...... pop http https and everything else is working just fine..... thanks in advance