My GS-R250S Plus/Duo ADSL Router does have an internal NAT Port forwarding
routine. I used to forward port 21 (FTP) to my internal lan machine 172.207
1.30. Then I installed M0n0wall and my FTP machine´s IP changed to 192.168.1
198. So I changed my ADSL Router NAT Port forwarding routine to forward port
21 (FTP) to the new 192.168.1.198 lan IP. I also configured M0n0wall´s NAT
and firewall rules to allow traffic to my internal IP, but I can´t connect
to my FTP machine outside network anymore...