FTP access from outside

[Dimitri Yioulos <dyioulos@firstbhph.com>]

Hello, colleagues.

I'm embarassed to ask for help on this (it should be trivial to set up), but 
I'm having no luck:

I'd like to enable FTP access to my web server, which is sitting in a DMZ, 
from outside.  I've add proftpd, and believe I've set it up properly.  I can 
access FTP from my LAN, but not from outside.  I've added the following rules 
to allow access:

-A FORWARD -p tcp -m tcp -d 192.168.1.3 -i eth0 -o eth2 --dport 21 -j ACCEPT
-A PREROUTING -p tcp -m tcp -d 67.x.x.x -i eth0 --dport 21 -j DNAT 
--to-destination 192.168.1.3
-A POSTROUTING -s 192.168.1.3 -o eth0 -j SNAT --to-source 67.x.x.x

where eth0 is public interface and eth2 is DMZ interface

What have I missed (or messed up)?

As always, thanks.

Dimitri