RE: OWA 2003
- From: "Moon, Brendan" <bmoon@xxxxxx>
- To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
- Date: Sun, 22 Jan 2006 15:17:57 -0500
I see three other 'cons' to putting an Exchange Front-End server in a
DMZ that have not been mentioned:
1) All OWA related Front-End <-> Back-End traffic is clear-text TCP/80.
Regardless of whether or not you use SSL between the client and
Front-End server. Depending on how much you trust your DMZ, you may be
putting your e-mail content at risk of sniffing to a compromised server
in the DMZ.
2) Exchange Front-End servers must be members of a domain. Many
organizations don't like putting members of their internal
forest/domains in a DMZ. The risk is that domain members have a level
of inherent trust between themselves -- which you may not want crossing
your DMZ/trusted enclave boundary.
3) The firewall consideration is also frequently underestimated.
Exchange servers really should be able to talk with 'all' DCs and 'all'
other Exchange servers in the same organization. So its not as simple
as opening a few ports between a single Front-End and a single Back-End
server. While a 1:1 ratio may seem to work in small deployments -- you
will sacrifice functionality and reliability in larger environments. In
a large enterprise a potentially compromised DMZ Front-End Exchange
server would have open access through a firewall to many other critical
servers (DCs, GCs, Exchange, etc.) in your trusted enclave(s).
Thomas - perhaps you could elaborate on some of the downsides to reverse
proxying a Front-End server which resides in a non-DMZ trusted network.
- Brendan Moon
-----Original Message-----
From: Carl Houseman [mailto:c.houseman@xxxxxxxxx]
Sent: Sunday, January 22, 2006 11:55 AM
To: [ExchangeList]
Subject: [exchangelist] RE: OWA 2003
http://www.MSExchange.org/
As always, there are two camps on this. One camp wants to blow holes in
the firewall to permit the FE to talk to the BE. The other wants to
avoid that.
See "Figure 1 Secure Firewall Structure" here:
<http://www.microsoft.com/technet/security/prodtech/exchangeserver/secmo
d44.
mspx>
So, Microsoft favors the FE and BE servers on the same security zone,
when their ISA server is used as reverse proxy.
Have fun arguing with Microsoft. When you convince them and they change
their document, let us know. Otherwise, we already know your opinion,
so thanks for sharing.
Carl
-----Original Message-----
From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxx]
Sent: Sunday, January 22, 2006 11:31 AM
To: [ExchangeList]
Subject: [exchangelist] RE: OWA 2003
http://www.MSExchange.org/
About why putting a front-end, Internet facing, Exchange Server on the
same security zone as the back end Exchange servers. I'd like to
understand the misconceptions that underlie that assertion, so that we
can shoot them down and show how foolish they are.
Thanks!
Tom
Thomas W Shinder, M.D.
Site: www.isaserver.org
Blog: http://spaces.msn.com/members/drisa/
Book: http://tinyurl.com/3xqb7
MVP -- ISA Firewalls
> -----Original Message-----
> From: Andy David [mailto:adavid@xxxxxxxxxxxxx]
> Sent: Sunday, January 22, 2006 10:30 AM
> To: [ExchangeList]
> Subject: [exchangelist] RE: OWA 2003
>
> http://www.MSExchange.org/
>
> About what?
>
>
> -----Original Message-----
> From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxx]
> Sent: Sunday, January 22, 2006 11:25 AM
> To: [ExchangeList]
> Subject: [exchangelist] RE: OWA 2003
>
> http://www.MSExchange.org/
>
> Hi Andy,
>
> You are patently WRONG about that. Where did you get such incorrect
> advice? Because whoever told you that is most definitely not security
> minded.
>
> You might want to share the rationale you used for this assertion so
> that we can shoot it down sequentially and rationally.
>
> Tom
>
> Thomas W Shinder, M.D.
> Site: www.isaserver.org
> Blog: http://spaces.msn.com/members/drisa/
> Book: http://tinyurl.com/3xqb7
> MVP -- ISA Firewalls
>
>
>
> > -----Original Message-----
> > From: Andy David [mailto:adavid@xxxxxxxxxxxxx]
> > Sent: Saturday, January 21, 2006 9:57 PM
> > To: [ExchangeList]
> > Subject: [exchangelist] RE: OWA 2003
> >
> > http://www.MSExchange.org/
> >
> > http://www.microsoft.com/downloads/details.aspx?FamilyID=E6466
> > 6FC-42B7-4
> > 8A1-AB85-3C8327D77B70&displaylang=en
> >
> >
> > Don't put it in the DMZ however. That's just foolish. Put a
> > reverse-proxy in the DMZ if you must. Otherwise, keep the Front End
> > server behind your firewall.
> >
> >
> >
> > -----Original Message-----
> > From: Dave Flaim [mailto:thethin@xxxxxxxxxxxxxxxxxxxxxxx]
> > Sent: Saturday, January 21, 2006 10:41 PM
> > To: [ExchangeList]
> > Subject: [exchangelist] OWA 2003
> >
> > http://www.MSExchange.org/
> >
> > Is it possible to install OWA on a separate server than the Excange
> > 2003 server - ie. we would like to place he OWA server in
> the DMZ. Of
>
> > so does anyone have a procedure or reference?
> >
> > Thanks
> > Dave Flaim
> > CVI
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