DNS forward to virtual device on a Linux Server

[LoCrux]

ThanX for your effords in advance…

I just try to setup my own server, for this I created several virtual devices on my server (ubuntu 10.04.1).
At my domain hosters page I created a subdomain e.g.  ftp.mydomain.eu and pointed the A-Record to my IP (static).
Now I want all the ftp access through my virtual device eth0:2 (set to 192.168.42.223). For that I created a virtual FTP server
using proFTPd only responding to 192.168.42.223. From inside my LAN I have no proplems accessing the virtual server.
From WAN side (took a 30m patch cable to my neighbours router) I always end up at the default FTP server.

At the pfSense DNS forwarder I tried every combination to forward to my virtual eth0:2 device.

eg
host: ftp
domain: ftp.mydomain.eu
ip: 192.168.42.223

or
host: ftp
domain: mydomain.eu
ip: 192.168.42.223

always ending up at the standard server from WAN.

So is there a way to forward to the eth0:2 IP?
Or is there a possibility to assign a static DHCP lease to the virtual IPs?

P.S.

I also tried to assing the eth0:2 IP to pfSense's Virtual IP addresses.
Type: Other
Interface: LAN
IP Address(es): Single Address / 192.168.42.223