ar as teisingai suprantu???
jugiantis is isores y 2222 porta firewall prafowardins ji y vietini 22 porta
man ta pati reikia su 25 smtp portu padaryti
is isores jungtusi 587 portu o firewallas ji nukreiptu ji 25 port
<< SHOREWALL dirbama >>

Example 7:

You wish to accept connections from the internet to your firewall on 
port 2222 and you want to forward them to local system 192.168.1.3, port 22
         #ACTION  SOURCE DEST                PROTO   DEST    SOURCE ORIGINAL
         #                                           PORT    PORT(S) DEST
         DNAT     net    loc:192.168.1.3:22  tcp     2222