[isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- From: "Jason Jones" <Jason.Jones@xxxxxxxxxxxxxxxxx>
- To: <isapros@xxxxxxxxxxxxx>
- Date: Sat, 13 Jan 2007 23:46:25 -0000
Only seen the issue when BE's in perimeter.
________________________________
From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx]
On Behalf Of Thor (Hammer of God)
Sent: 12 January 2007 18:31
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
If your FE doesn't have a store, it's not a problem. Not that I have
seen, anyway.
t
On 1/12/07 6:27 AM, "Gerald G. Young" <g.young@xxxxxxxx> spoketh to all:
If it's participating in the domain, add the subnet to AD,
especially if you have more than one AD site (I consider this a best
practice). A lot of funny things can occur with Active Directory aware
applications when they can't tell which site they belong to. Exchange
(2003), for instance, won't start an information store.
Cordially yours,
Jerry G. Young II
Product Engineer - Senior
Platform Engineering, Enterprise Hosting
NTT America, an NTT Communications Company
22451 Shaw Rd.
Sterling, VA 20166
Office: 571-434-1319
Fax: 703-333-6749
Email: g.young@xxxxxxxx
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Jason Jones
Sent: Friday, January 12, 2007 6:53 AM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
Either way, I think the idea of an intranet CAS and extranet CAS
is probably a good approach - the extranet CAS one would assume could
then go into the auth access perimeter network whilst the intranet one
could stay on the LAN. In this model, each CAS has a different security
risk and hence could be put into different security zones.
Would it be such a bad thing to add the perimeter subnet to the
AD site? It will have domain members in it after all...
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: 12 January 2007 05:35
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
doing a little bit more reading the only thing i can think might
be the reason is that apparently each mailbox server needs to have a CAS
server in its AD site. Therefore they recommend you keep the cas box on
the same lan. Also in multi domain environments this would add more
design considerations. Also in larger environments you might need 2 CAS
boxes, one for internal users and one for external users, for the sake
of keeping outbound lan access out of the dmz or better design.
but im not sure about the whole idea of the "swiss cheese"
argument. seems a bit like flogging a dead horse to me..i dont see how
or why it wouldn't work in the dmz environment.
greg
----- Original Message -----
From: Thomas W Shinder <mailto:tshinder@xxxxxxxxxxx>
<mailto:tshinder@xxxxxxxxxxx>
To: isapros@xxxxxxxxxxxxx
Sent: Friday, January 12, 2007 3:22 PM
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
WORD!
I'll gladly joining you in that public nut-kicking when
the time comes. What I want to understand first is what are the protocol
requirements for the CAS to the back-end components, and what their
rationale is for making the statements that have been reported so far.
They might have a good point, and if they have it, I want to hear it.
But if the point is 'it's too hard" or "I don't understand network
security, I just say what my boss tells me to say" or "I'm on the take
with Syphco" then those aren't valid and body parts will deserve some
shaking up in the public square. The least they can do is state "we
don't have the time or inclination to show you have to provide the
highest level of network security, but it is possible to do it right,
we're just not going to show you how to do it" as a disclaimer. With
that, we can then go ahead and help those who want to be helped :-)
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Thor (Hammer of God)
Sent: Thursday, January 11, 2007 6:40 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
It may be just this type of "beating it to death" that
is required to get the Exchange group's attention. I don't really care
if they don't support "perimeter network" deployments as long as ISA is
an exception. I have every intention to ensure that an ISA
authenticated perimeter network DMZ segment "in front" of the CAS server
is fully supported if the proper protocols are allowed. I will make
sure to press them into officially stating why it is not supported.
Even so, if they try that, I will publicly kick them in the nuts.
t
On 1/11/07 4:15 PM, "Jason Jones"
<Jason.Jones@xxxxxxxxxxxxxxxxx> spoketh to all:
Hi Amy,
I am not really sure for their reasoning, but think it
is based around the "Swiss cheese", don't pass intradomain traffic
across a normal firewall argument.
Sorry, my bad for using the term DMZ, the exact phrase
used by Scholl is "It's true. The Client Access Server (CAS), which
among other things includes the OWA feature, is not supported in a
perimeter network (aka a DMZ). Instead you'll deploy one or more CASs
inside your organization and put a robust firewall such as ISA 2006 in
front of it." I am guessing from experience of other Exchange team
recommendations that when they say perimeter network they really mean a
traditional DMZ which is created using traditional packet filter
firewalls. The recommended deployment is to put the CAS on the internal
network e.g. on the same network as the Exchange back-end servers. Once
the CAS is on the internal network, it should then be published to the
Internet using ISA.
This design if fine if you want a simple open network
where all servers exist in the same security zone and hence all trust
each other, but many people are now trying to better this design by
placing different types of servers into different security zones based
upon their risk level and internet presence - say hello to the ISA auth
access perimeter network! ;-)
Basically I think it all harks back to the "don't put
domain members in a DMZ" mantra which is a pretty fair statement when
using PF firewalls like PIX, but things have moved on as least privilege
authenticated access perimeter networks with ISA are now getting
advanced enough to challenge this argument. Maybe the difference between
a PIX firewall and ISA firewall is just too subtle for some people???
Think we have now done this to death now!! - be very
surprised if the Exchange team go back on these type of statements
though. I remember Tom banging his head against a brick wall with Henrik
based upon one of his MSExchange.org articles which said "not in the
DMZ" type statements.
JJ
________________________________
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Amy Babinchak
Sent: 11 January 2007 23:15
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
Jason,
What's the reasoning behind CAS not in the DMZ? Where to
they want it? Handing nude off the router? Behind a firewall?
If the later, then just drop the out dated DMZ language.
Most firewall admins think that DMZ means nude off the other port on my
nat box. Your least priv design puts CAS safely behind a firewall.
Amy Babinchak
Harbor Computer Services
________________________________
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Jason Jones
Sent: Thursday, January 11, 2007 5:58 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
Thanks Amy - maybe I am being a little oversensitive,
just didn't expect some of the initial responses.
I tend to avoid most of the main mailing lists, probably
for similar reasons as others, and I tend to hang out at isaserver.org
95% of the time. Hence maybe why only Tom (and Stefan) tend to see my
input and views on stuff.
Tom invited me to this list as he felt it would be a
good place for me to pose all the questions that he can't answer or go
unreplied on isaserver.org
I really do value the combined "ISA brain power" here,
but just think it could be a little more forgiving and friendly at
times...having said that I have found answers here that I just couldn't
get elsewhere, so don't misunderstand me as ungrateful.
Anyhow back to the "core issue", from what I hearing
from Exchange MVP contacts, MS are playing the "CAS in a DMZ is totally
unsupported" tune very strongly. This is a real shame as it looks like I
will never be able to deploy the existing least privilege design with
Exchange 2007 without fear of customers coming back to us after trying
to log PSS calls or getting other non-ISA firewall guys in who slate the
design...oh well, at least ISA will still involved to some degree, just
not as cool as it could be...
JJ
________________________________
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Amy Babinchak
Sent: 11 January 2007 15:09
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
Jason don't get discouraged. The changes in Exchange are
monumental so there are bound to be disagreements and changes of opinion
on how to best secure it. The concept of an authenticated access DMZ in
a separate security zone allowing only a very minimal set of protocols
is a completely foreign concept to 99% of firewall admins out there.
That fact you are even thinking about this stuff put you in an elite
class. The rest are still poking holes and setting up VLANs.
Tom, Thor and Jim can be a bit clubby and a little
overly poky to new comers. It's a twitch they developed after
participating on the ISA server mailing list. It got worse when they
decided to join a general purpose SBS list. I'm not sure that they'll
ever completely recover.
Amy
________________________________
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Jason Jones
Sent: Thursday, January 11, 2007 5:47 AM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
Wish I had never asked now...sometimes, some of you guys
really don't make it easy for new people to try express their views and
pose questions for comment without being slapped down. One minute I am
being labelled as an "idiot" for my comments/views, the next minute
someone else who says the same thing as me is now right and not
challenged. What gives?
I know many of you guys don't know me from Adam, but
kinda unfair to just assume I know jack about ISA and secure network
design just because I'm not "part of the club".
Anyhow, thanks to Tim and Tom for seeming to share my
disappointment with the decision made by the Exchange 2007 team...I
think I need to try and find out how "official" their lack of support
with 2k7 is going to be before I can continue recommending the least
privilege model I have been using for Exchange 2003.
________________________________
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Jim Harrison
Sent: 11 January 2007 04:30
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
..maybe I'm just tired...
I spent two hours trying to get home tonight and I'm
clearly not in my mind (right or otherwise).
Forget I wrote and we'll start over tomorrow...
From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Thor (Hammer of God)
Sent: Wednesday, January 10, 2007 8:18 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter
Networks
That's exactly what I'm talking about. And precisely
the configuration I deploy:
My FE is in the authenticated segment of the DMZ - and a
member of my internal domain; however, the "recommended protocols" the
Exchange group recommends are not necessary- and thus, Steve's
contention that "CIFS and all that other stuff... Might as well just be
internal" I reject. I only allow Kerberos-Sec, LDAP, LDAP GC, Ping and
DNS only from my FE to the internal DC's. And only HTTP to the BE's.
Even if the other prots WERE required, it would still be
far smarter to deploy the FE in the authenticated DMZ with limited
access than to just give full stack access to the ENTIRE internal
network. This is a deployment of a services made available (initially)
to a global, anonymous, untrusted network.
Maybe I'm not properly articulating my point, but I have
to say I'm really surprised that we are having this conversation...
t
On 1/10/07 7:10 PM, "Jim Harrison" <Jim@xxxxxxxxxxxx>
spoketh to all:
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]
<mailto:isapros-bounce@xxxxxxxxxxxxx%5d>
<mailto:isapros-bounce@xxxxxxxxxxxxx%5d> 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]
<mailto:isapros-bounce@xxxxxxxxxxxxx%5d>
<mailto:isapros-bounce@xxxxxxxxxxxxx%5d> 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&q=cas+dmz+i
sa&rnum=2&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>
<http://groups.google.co.uk/group/microsoft.public.exchange.design/brows
e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+i
sa&rnum=2&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>
<http://groups.google.co.uk/group/microsoft.public.exchange.design/brows
e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+i
sa&rnum=2&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>
<http://groups.google.co.uk/group/microsoft.public.exchange.design/brows
e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+i
sa&rnum=2&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.
All mail to and from this domain is GFI-scanned.
Other related posts:
- » [isapros] ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
- » [isapros] Re: ISA, Exchange 2007 and Perimeter Networks
