Redirecting ftp

[Debs <debs@utysket.dk>]

Hi

I'm having at strange problem with a Pure-Ftpd-MySQL. I got at firewal that
also hosts ftp and a smtp-gateway, plus the FW redirects web and some other
ports to another server. 
The firewall is on 10.0.0.0/24 and it's outside IP is 10.0.0.2. The inside
is only one NIC, but it's divided into four. 
¤ eth1 - 172.16.0.1/27 (DHCP,DNS,GATEWAY)
¤ eth1:1 - 172.16.0.4/27 (Ftp)
¤ eth1:2 - 172.16.0.4/27 (MAIL)
¤ eth1:3 - 172.16.0.33/29 (gateway for subnet)

My problem is when I try to connect to the ftpd-server from the outside. I
can connect to the server, and the ftpd-log confirm that the user is logged
in "[INFO] nogetfx is now logged in". But then the client, in this case
gftp, stall. In gftp it's stock a "Receiving file names...". 

Part of the iptables-script:
       PUBLIC='172.16.0.4'
       WAN_IP='10.0.0.2'

   # ¤¤¤ FTP ¤¤¤
        iptables -t nat -A PREROUTING -d $WAN_IP -p udp --dport 20 -j DNAT
--to $PUBLIC:21
        iptables -t nat -A PREROUTING -d $WAN_IP -p tcp --dport 20 -j DNAT
--to $PUBLIC:21
        iptables -t nat -A PREROUTING -d $WAN_IP -p udp --dport 21 -j DNAT
--to $PUBLIC:21
        iptables -t nat -A PREROUTING -d $WAN_IP -p tcp --dport 21 -j DNAT
--to $PUBLIC:21

        iptables -A INPUT -p udp --dport 20 -d $PUBLIC -j ACCEPT
        iptables -A INPUT -p tcp --dport 20 -d $PUBLIC -j ACCEPT
        iptables -A INPUT -p udp --dport 21 -d $PUBLIC -j ACCEPT
        iptables -A INPUT -p tcp --dport 21 -d $PUBLIC -j ACCEPT


BTW is udp necesarry..?

/Lars

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