From: Herbert Poetzl (herbert_at_13thfloor.at)
Date: Wed 22 Sep 2004 - 22:16:58 BST
On Wed, Sep 22, 2004 at 11:05:15PM +0200, Gilles wrote:
> Hello.
> 
> > [...]
> > ... anyway discussion of those issues is
> > appreciated I'd say, so let's keep the talk going ...
> > 
> 
> Fine :-)
> In fact, I'd like to understand what is the minimal hardware
> configuration, necessary to build a "complete" IT infrastructure,
> i.e. that would at least comprise services such as
>  - file
>  - web
>  - mail
>  - database
>  - backup
> 
> The aim is to be able to propose a "full-featured" solution to 
> small organizations, which have limited resources, and be able
> to emphasize a level of security similar to the expensive solution
> where each server would be on its own physical box.
> 
> E.g. if 5 people work with a computer each, it might be difficult to
> get them buy twice as many computers...
> 
> I imagined that the minimum would be 2 extra computers: one for the
> firewall (H1) and the other for the services (H2).
> 
>                  [           (nic2) ] <----> [ (nic3) H2 ]
>  Internet <----> [ (nic1) H1        ]
>                  [           (nic4) ] <----> [ (nic5) H3 ]
>                                              [ (nic6) H4 ] etc.
> 
> H3 to H8 would be the 5 end-user machines, on a different subnet than
> H2 is on.
okay, this gives me a better picture of the desired
setup, and in this case I'd opt for the following
(maybe unconventional?) setup:
 Internet <---> [nic1 H1 nic2] <---> [nic3 H2 nic4] <---> H3,H4,H5 ...
with a border firewall on H1 and a simple firewall
and proxy solution on H2, a single vserver on H1 
with CAP_NET_ADMIN and vservers for each service 
on H2. why?  because!
no seriously, IMHO this would allow to do the following 
things in a secure way:
 
 - in office traffic between hosts
 - controlled usage of the services on H2 from inside
 - double checked services to the outside
 - monitored firewall, only the single vserver is
   communicating with the internet (e.g. tripwire
   is running on the host) ...
 - firewall host only reachable from inside
 - no issues on service maintenance, just close the 
   service on the border fw
 - a second layer of protection from vservers for
   the services and the firewall stuff
 - ... 
HTH,
Herbert
> But it can be objected that H2 shouldn't host both the public (e.g. web)
> and the private (e.g. database) services.
> 
> So, I was wondering:
> Is it possible to have "virtual" networks inside H2?  If yes, how?
> Even if it is possible, if each service on H2 runs inside its own vserver,
> is it necessary to have a virtual DMZ?
> Would it be enough if each service is configured to listen to its IP address
> only?
> Are there obvious security threats?
> 
> 
> > > P.S. I can't seem to be able to subscribe to the ML,
> 
> I'm subscribed now.
> 
> 
> Best regards,
> Gilles
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