Сейчас конфиг такой:
rc.conf
Internet  
ifconfig_em0="inet 1.1.1.1 netmask 255.255.255.248"  
Alias internet ftp  
ifconfig_em0_alias0="inet 1.1.2.1 netmask 255.255.255.255"  
Local Network  
ifconfig_em1="inet 192.168.1.10 netmask 255.255.255.0"  
DMZ  
ifconfig_em2="inet 192.168.2.10 netmask 255.255.255.0"  

Правила

#!/bin/sh  

#reset rules  
ipfw -q -f flush  

#-------main network-------
#macro  
net="em0"  
lan="em1"  
dmz="em2"  
cmd="ipfw -q add"  
skip="skipto 2000"  

#kernel nat 1 config  
ipfw -q nat 1 config if $net same_ports unreg_only \  
redirect_port tcp 192.168.2.31:21 21 \  
redirect_port tcp 192.168.2.31:20 20 \  
redirect_port tcp 192.168.2.31:30000-31000 30000-31000 \  
redirect_port tcp 192.168.1.58:443 443 \  
redirect_port tcp 192.168.2.60:25 25  

#-------rules network -------
#allow networks  
$cmd 0001 allow all from any to any via $lan  
$cmd 0002 allow all from any to any via $dmz  
$cmd 0004 allow all from any to any via lo0  

#kernel nat 1 in  
$cmd 0040 nat 1 ip from any to any in via $net  

#dinamic rules  
$cmd 0050 check-state  

#-------out network-------
#allow trafic from gate out  
$cmd 0060 $skip tcp from any to any out via $net setup keep-state  
$cmd 0061 $skip udp from any to any out via $net keep-state  
$cmd 0062 $skip icmp from any to any out via $net keep-state  

#exchange trafic out  
$cmd 0070 $skip tcp from 192.168.1.58 443 to any  
$cmd 0071 $skip tcp from 192.168.2.60 25 to any  

#dmz ftp trafic out  
$cmd 0072 $skip tcp from 192.168.2.31 20,21,30000-31000 to any  

#-------in network-------
#exchange trafic in  
$cmd 0130 allow tcp from any to 192.168.1.58 443  
$cmd 0131 allow tcp from any to 192.168.2.60 25  

#dmz ftp trafic in  
$cmd 0130 allow tcp from any to 192.168.2.31 20,21,30000-31000  

#-------end network-------
#deny all  
$cmd 0500 deny log all from any to any in via $net  
$cmd 0510 deny log all from any to any out via $net  

#kernel nat 1 out  
$cmd 2000 nat 1 ip from any to any out via $net  
$cmd 3000 allow ip from any to any  

#deny all other  
$cmd 4000 deny log all from any to any