ipfw - accessing DMZ from LAN

[Marek Salwerowicz]

Hi all,

I have set up a new router for my network, with separated DMZ zone for 
my internet servers. I'd like computers from my LAN to be able to 
connect to DMZ zone.

My ISP provided me some public IP's, so right now configuration looks 
like this:

Router with 4 NICs:
#public ISP
ifconfig_vr3="inet xx.yy.zz.171 netmask 255.255.255.248"
ifconfig_vr3_alias0="inet xx.yy.zz.170 netmask 255.255.255.255"
ifconfig_vr3_alias1="inet xx.yy.zz.172 netmask 255.255.255.255"
ifconfig_vr3_alias2="inet xx.yy.zz.173 netmask 255.255.255.255"

The first IP, with suffix .171 I want to be used as real router's IP, 
and public IP for computers in my LAN.
All 3 aliases I want to be redirected to DMZ (one public IP for each 
server in DMZ)

#DMZ
ifconfig_vr2="inet 192.168.0.1 netmask 255.255.255.0"

#LAN
ifconfig_vr0="inet 10.0.0.1 netmask 255.255.255.0"

I've set up in natd.conf:

use_sockets yes
same_ports yes
interface vr3
dynamic yes
unregistered_only yes
redirect_address 192.168.0.10 xx.yy.zz.170 #DMZ host 1
redirect_address 192.168.0.20 xx.yy.zz.172 #DMZ host 2
redirect_address 192.168.0.30 xx.yy.zz.173 #DMZ host 3

Right now everything works from the Internet - if I do ssh to 
xx.yy.zz.170, I really can connect to host 192.168.0.10 etc.

The problem is that when I want to connect from my 10.0.0.0/24 network 
(and even from router) to any DMZ host, using it's public address (any 
of xx.yy.zz.{170,172,173} ), I can't connect and in fact I am connecting 
to the router..
So I am unable to access my web, mta, ftp servers that are located in DMZ

My ipfw firewall script looks as follows:

#!/bin/sh

cmd="ipfw -q"

DMZ="192.168.0.0/24"
LAN="10.0.0.0/24"

kldstat -q -m dummynet || kldload dummynet
$cmd flush

$cmd add 80 divert natd ip from any to any via vr3
$cmd add 90 allow ip from any to any via lo0

$cmd add 100 allow ip from any to me
$cmd add 101 allow ip from me to any

$cmd add 500 deny ip from $DMZ to $LAN
$cmd add 510 deny ip from $LAN to $DMZ


$cmd add 10000 allow ip from any to any

I know I've blcoked traffic between DMZ and LAN, but I wanted them to 
contact via public IPs.. but now I'm not sure if it's possible...

Can you give me some hints on how to properly configure my router?

Regards,

-- 
Marek Salwerowicz