Hello. Please somebody gie me a hint.
I run a Slack 10.2 box as router and firewall (rc.firewall-iptables-stronger with default policy DROP).
On one of the windose machines in LAN, runs a ftp server(port 21).
The problem follows: I want to access the ftp server form outside(WAN) on port 2001 but can't. If I use port 21, it works as marvell.
Here the lines:

$IPTABLES -t nat -A PREROUTING -p tcp -i $EXTIF --dport 2001 -j DNAT --to 192.168.1.22:21
$IPTABLES -A FORWARD -p tcp -i $EXTIF --dport 2001 -j ACCEPT

and this doesen't work. But, if I replace --dport 2001 with --dport 21, it works perfect.

.... can someone give me a clue pls??