Re: Firewall and DMZ topology

[Aaron Fisher <aaron-fisher () iinet net au>]

After seeing this topic go on for some time why not have a router with 2 
network interfaces one interface you would have your firewall and then 
internal LAN

                               <> Firewall <> LAN
internet <> router
                               <> Firewall <> DMZ

The other would have your firewall and then DMZ. You can then deny all 
traffic with a source add from the DMZ going to a dest of your LAN. This 
still wouldnt stop traffic originally coming from the LAN as im assuming 
you would be using NAT so the source address would be the routers 
external interface and it was initiated by the LAN. Hopefully this 
sugestion makes sense however routers with 2 10/100 network ports can be 
rather expensive.

Anyways thats my 2cents

Aaron

Des Ward wrote:

> The first one does not have to use two separate firewalls, just have an
> extra NIC to segment the LAN and DMZ.
>
> You bottom two examples are as follows:
>
> The first one is far too complex and was how I thought a DMZ was supposed to
> be until I realised that it just wasn't needed.
>
> The second means that all traffic has to traverse your LAN to get to the
> 'Unprotected' DMZ systems and also could leave your internal LAN open to
> attack.
>
> The main thing to remember is that the DMZ is designed to be accessible to
> the outside world.  You do want this segmented from the rest of the LAN in
> the easiest way possible.
>
> Just my .002667 cents worth (After converting from the BRITISH and not
> ENGLISH pound)
>
> -----Original Message-----
> From: Chris Berry [mailto:compjma () hotmail com] 
> Sent: 10 June 2003 01:53
> To: security-basics () securityfocus com
> Subject: Re: Firewall and DMZ topology
>
>  
>
> > From: Christopher Ingram <cmi () crystalsands net>
> > So, the below setup is not decent for a corporate LAN. Ideally, the DMZ 
> > should sit on a seperate connection to the Internet from the rest of the 
> > network, using a different ISP and therefore, different IP block. This 
> > provides the most isolation.
> >    
>
> I'm afraid I don't see how that:
>
> internet --> Firewall --> Lan
>
> internet --> Firewall --> DMZ
>
> would be any more secure than this:
>
> internet --> Outer Firewall --> DMZ --> Inner Firewall --> LAN
>
> or this:
>
> internet -->  Firewall --> LAN
>                             --> DMZ
>
> which are the setups that I've seen.  Can you give some 
> justification/explanation on why you think that would be better?
>
> Chris Berry
> compjma () hotmail com
> Systems Administrator
> JM Associates
>
> "All I want is a few minutes alone with the source code for the universe and
>
> a quick recompile."
>
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The Gartner Group just put Neoteris in the top of its Magic Quadrant,
while InStat has confirmed Neoteris as the leader in marketshare.
    
Find out why, and see how you can get plug-n-play secure remote access in
about an hour, with no client, server changes, or ongoing maintenance.
         
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