[isapros] Re: ISA, Exchange 2007 and Perimeter Networks

From: "Thomas W Shinder" <tshinder@xxxxxxxxxxx>
To: <isapros@xxxxxxxxxxxxx>
Date: Wed, 10 Jan 2007 21:45:20 -0600
What's wrong with that? There is granularity of security zone
definitions and membership, even within a domain. Just like what we've
done with the FE Exchange Server, there's no qualitative or quanitative
differences here that I can tell.
 
Thomas W Shinder, M.D.
Site: www.isaserver.org <http://www.isaserver.org/> 
Blog: http://blogs.isaserver.org/shinder
Book: http://tinyurl.com/3xqb7 <http://tinyurl.com/3xqb7> 
MVP -- ISA Firewalls

 


________________________________

        From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Jim Harrison
        Sent: Wednesday, January 10, 2007 7:11 PM
        To: isapros@xxxxxxxxxxxxx
        Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
        
        

        C'mon, Tim; I know what your deployment recommendations are;
this isn't it.

        He wants to extend his domain via "remote membership"; not
create a separate domain.

         

        From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Thor (Hammer of God)
        Sent: Wednesday, January 10, 2007 4:26 PM
        To: isapros@xxxxxxxxxxxxx
        Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks

         

        Because it's safer that way, that's why... That's what an
authenticated access DMZ perimeter is for- with a CAS server that
presents logon services to any Internet user, I would (and, in fact,
require) that the server be in a least-privileged authenticated access
perimeter network that limits that servers communications to the minimum
required for required functionality - and only to the hosts it needs to
talk to.
        
        Let's say there is a front-end implementation issue or coding
vulnerability: the CAS on the internal network would allow unfettered,
full-stack access to the internal network.  A CAS in a perimeter DMZ
would mitigate potential exposure in the event of a 0day or
configuration issue. 
        
        "Safer on the internal network" is a complete misnomer when it
comes to servers presenting services to an untrusted network. 
        
        t
        
        
        On 1/10/07 3:04 PM, "Jim Harrison" <Jim@xxxxxxxxxxxx> spoketh to
all:

        Why would you want to place a member of your internal domain in
your DMZ, fer chrissakes?!?
        Hosting any domain member in the DMZ is a difficult proposition;
especially where NAT is the order of the day.
        You can either use a network shotgun at your firewall or attempt
to use your facvorite VPN tunnel across the firewall to the domain.
        
        Jim

        
________________________________


        From: isapros-bounce@xxxxxxxxxxxxx on behalf of Jason Jones
        Sent: Wed 1/10/2007 2:35 PM
        To: isapros@xxxxxxxxxxxxx
        Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
        
        From what I can gather, the new CAS role now uses RPC to
communicate with the back-end (not sure of new name!) servers so I am
guessing that this is an "RPC isn't safe across firewalls" type stance.
Which I guess for a PIX, is a pretty true statement.
        
        Just think how much safer the world will be when firewalls can
understand dynamic protocols like RPC...maybe one day firewalls will
even be able to understand and filter based upon RPC interface...maybe
one day... :-D ;-)
        
        Shame the Exchange team can't see how much ISA changes the
traditional approach to DMZ thinking...kinda makes you think that both
teams work for a different company :-(
        Jason Jones | Silversands Limited | Desk: +44 (0)1202 360489 |
Mobile: +44 (0)7971 500312 | Fax: +44 (0)1202 360900 | Email:
jason.jones@xxxxxxxxxxxxxxxxx <mailto:jason.jones@xxxxxxxxxxxxxxxxx>
<mailto:jason.jones@xxxxxxxxxxxxxxxxx>  
        
         

        
________________________________


        From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Greg Mulholland
        Sent: 10 January 2007 22:07
        To: isapros@xxxxxxxxxxxxx
        Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
        
        I seriously hope that they have take different paths and these
are not limitations on the software or it is going to mean a nice little
redesign and break from custom..
        
        Greg

        ----- Original Message ----- 
        From: Jason Jones <mailto:Jason.Jones@xxxxxxxxxxxxxxxxx>
<mailto:Jason.Jones@xxxxxxxxxxxxxxxxx>   
        To: isapros@xxxxxxxxxxxxx 
        Sent: Thursday, January 11, 2007 8:25 AM
        Subject: [isapros] ISA, Exchange 2007 and Perimeter Networks
        
        
        Hi All, 
        
        I heard today from an Exchange MVP colleague that members of the
Exchange team (Scott Schnoll) are saying that they (Microsoft) do not
support placing the new Exchange 2007 Client Access Server (like the old
Exch2k3 FE role) role into a perimeter network. Has anyone else heard
the same? This sounds very similar to Exchange admins of old when they
didn't really understand modern application firewalls like ISA could do
- RPC filter anyone???
http://groups.google.co.uk/group/microsoft.public.exchange.design/browse
_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+isa&rn
um=2&hl=en#4db165c21599cf9b
<http://groups.google.co.uk/group/microsoft.public.exchange.design/brows
e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&amp;q=cas+dmz+i
sa&amp;rnum=2&amp;hl=en#4db165c21599cf9b>
<http://groups.google.co.uk/group/microsoft.public.exchange.design/brows
e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+isa&r
num=2&hl=en#4db165c21599cf9b>  
        
        I have just about managed to convince Exchange colleagues (and
customers) of the value of placing Exchange FE servers in a separate
security zone from BE servers, DC's etc and now I here this...
        
        Are the Exchange team confusing the old traditional DMZ's with
what ISA can achieve with perimeter networks? 
        
        From what I believe, it is good perimeter security practice to
place servers which are Internet accessible into different security
zones than servers that are purely internal. Therefore, the idea of
placing Exchange 2003 FE servers in an ISA auth access perimeter network
with Exchange 2003 BE servers on the internal network has always seemed
like a good approach. It also follows a good least privilege model. 
        
        Is this another example of the Exchange and ISA teams following
different paths???? 
        
        Please tell me that I am wrong and that I am not going to have
to start putting all Exchange roles, irrespective of security risk, on
the same network again!!!!
        
        Comments? 
        
        Cheers 
        
        JJ 

        All mail to and from this domain is GFI-scanned. 

         

         

        All mail to and from this domain is GFI-scanned.
Follow-Ups:
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  - From: Jim Harrison
[isapros] Re: ISA, Exchange 2007 and Perimeter Networks

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