Check to see that the "ip_masq_ftp" module is loaded. To do this, log into the MASQ server and run the command "/sbin/lsmod". If you don't see the "ip_masq_ftp" module loaded, make sure that you followed the BASIC /etc/rc.d/rc.firewall recommendations found in Section 3.4. If you are implementing your own ruleset, make sure you include most of the examples from the HOWTO or you will have many susequent problems.