Re: DMZ howto

["Jörg Harmuth" <harmuth@mnemon.de>]

P theodorou wrote:
> I had a look on the NAT Howto , unfortunately explains the concept in brief
> therefore im thinking some things to be done
> 1) the Apache will be hosted on 192.168.1.2 (eth2)
> and my dynamic ip is something 22.22.22.22  (eth0)
> 
> somehow i declare
> iptables -t nat -A PREROUTING -p tcp --d 22.22.22.22  --dport 8080 -j 
> DNAT --to 192.168.1.2
> 
> -the above line my not beeing correct- so i redirect whatever touches 
> 22.22.22.22 to the
> internal 192.168.1.2 threfore conclusion 2 i need a static ip
> or a should never reboot the computer ! right ?

Not necessarily. There are some options.

1.) Instead of DNATing everything that is destined for
     22.22.22.22 to the other box - which (if i understand
     correctly) means every port -, you could DNAT everything
     that is destined to port 8080 to the other box. This means
     omitting -d 22.22.22.22. And at the very minimum, you
     must SNAT everything that leaves the box towards the internet.
     You can add the incoming interface, like -i ppp0.
2.) Register with DynDNS or the like. Then write your rule like this:
     ... -p tcp --dport 8080 -d dyndns.name.tld ...
     Do an iptables-save and every time your IP changes do
     an iptables-restore. You may like to write a script.
3.) Other things that may come to mind :)

HTH,

Joerg


> Please clarify
> 
> ps i phoned up my ISP they ask 5 pounds per month for static ip
> 
> 
>> From: "José R. \"Xous\" Negreira"<xous@xouslab.com.ar>
>> To: netfilter@lists.netfilter.org
>> Subject: Re: DMZ howto
>> Date: Thu, 22 Sep 2005 23:47:36 -0300
>>
>> Hi,
>>
>> First of all, technically and strictly speaking...a DMZ is not 
>> (always) a subnet. A DMZ is a independent network with a completely 
>> different IP ranges.
>> you can have an internal network of 192.168.1.0/24 network, and a DMZ 
>> 10.1.1.0/24, just to say some example....
>> Possible question: But...may it be a subnet?? Yes! of course...but 
>> it's not a must!
>>
>>
>> Your question:
>> My  ISP assigns me  a dynamic ip , therefore, is that a limitation
>> that could not allow me to develop the dmz subnet ?
>>
>> short answer:
>> No, there's no limitation, AFAIK
>>
>> long answer:
>> So now you have some doubts about the IP assigments huh?. Well...first 
>> of all, put the DMZ concept aside. Just to clarify concepts...I tell 
>> you more, it shouldn't bother too much this!
>>
>> You want to publish a web server, and the problem is how people 
>> outside reach to your web server.
>> If you have a static IP, there's no problem. People will reach you by 
>> typing http://xx.xx.xx.xx in the browser, being the xx.xx.. your IP 
>> address. But...that means that you have a web server INSTALLED on the 
>> firewall.... too bad. You want to have it on another machine, right?
>>
>> You will have a public IP, it doesn't matter if it's static or 
>> dynamic. In both cases, you'll want to use FORWARDING, and NAT 
>> (Network Address Translation), and that's now actually your real 
>> problem. What you do is simply 'touching' each packet header that 
>> traverses on the firewall, and redirecting wherever *you* want.
>>
>> Suppose that you have not one machine, but 3 webservers, but... Oh My 
>> god, you have only one IP!!  Well, using NAT, you can (for example) 
>> let people access to each webserver by typing:
>> http://xx.xx.xx.xx:80 (redirect to serverA, port 80)
>> http://xx.xx.xx.xx:81 (redirect to serverB, port 80)
>> http://xx.xx.xx.xx:82 (redirect to serverC, port 80)
>>
>> How to do NAT? The answer is on the question: (Recommended reading - 
>> NAT HOWTO)
>>
>> So, as you can see, your network(s) on the outside, is reduced to only 
>> one host (the firewall), behind it, it doesn't matter if it is just 
>> the firewall itself, a small network, one small network, one big 
>> network, or..... two or more *networks* (yes, you can return DMZ 
>> concept here!)!!. From the outside, it's transparent!!
>>
>> Well, re-reading this answer, it seemed to me like a big "concept 
>> salad", but... tryied a shot, hope it helped a bit! :)
>> And good luck!
>>
>> Regards
>>
>> -- 
>> _____________________________________________
>> Jose R. "Xous" Negreira.
>> PortalJAVA.com.ar - http://www.portalJAVA.com.ar <--  ** new!!! ** :P
>> XousLAB - http://www.xouslab.com
>> iptableslinux - http://www.iptableslinux.com
>> RDP - http://www.relacionesdepareja.com.ar
>>
>>
>>
>> P theodorou escribió:
>>
>>>
>>>
>>>
>>> Thank all of you for the replies,
>>>
>>> i have now a good understanding of
>>> the subject but before proceed  into building the dmz subnet i need
>>> to ask something :
>>>
>>> My  ISP assigns me  a dynamic ip , therefore, is that a limitation
>>> that could not allow me to develop the dmz subnet ?
>>>
>>> Is that correct or inacurrate ? Visitors shall need to type my ip to
>>> access my webpage,  but what im interesting is the development
>>> of the firewall itselfin terms of securing a network . It will never be
>>> used for real casesit is just for me to understand.
>>> the script that i have suggesetd uses static ip
>>>
>>> # 1.1 Internet Configuration.
>>> #
>>> INET_IP="194.236.50.152"
>>> HTTP_IP="194.236.50.153"
>>> DNS_IP="194.236.50.154"
>>> INET_IFACE="eth0"
>>> So,
>>> Can i develop dmz subnet without static ip   and dmz'ed services
>>> to be accessed on the Internet?
>>>
>>> Regards
>>>
>>>
>>>
>>
>>
>>
>>
> 
> 
> 
> 
> !DSPAM:43341f9e132561420745226!


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