ftp over RH router

Hello all, I have a problem with a RH72 box that I am using as a router
with ipchains but I can not get ftp to work from any windows boxes behind
the router. ftp works fine from the server, but when I use it in windows I
get connected to a site but when I type "ls" I get this:

502 Illegal PORT Command
425 Can't build data connection: Connection refused.

I have my firewall accept all input and output and forward set to MASQ all
from inside and it still hapens.

I remember reading something about needing to load certain modules for
some things to be masqued but I have another box where it works fine and I
thought with v7.2 it would have been compiled into the kernel anyway.


Any advice would be greatly appreciated.
Thanks.