Re: Outlook Web Access through ISA on internal- - - LAN

  • From: "Thomas W. Shinder" <tshinder@xxxxxxxxxxxxxxxxxx>
  • To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
  • Date: Fri, 17 May 2002 14:32:04 -0500

Hi Tim,

ISA Server shouldn't be passing any tokens. You either authenticate with
the Incoming Web Requests listener or you authentication with the OWA
box. There are limits on the authentication schemes so that you should
NOT enable authentication on both the listener and the site. The only
time dual authentication will work is when you use X.509 auth on the
listener and basic/digest/integrated auth on the Web server.

HTH,
Tom
www.isaserver.org/shinder


-----Original Message-----
From: Deus, Attonbitus [mailto:Thor@xxxxxxxxxxxxxxx] 
Sent: Thursday, May 16, 2002 11:40 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] Re: Outlook Web Access through ISA on internal- - -
LAN

http://www.ISAserver.org



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At 02:08 AM 5/16/2002, you wrote:

>The only thing I can think of that is causing this is something along
>these lines:
>- The Exchange server allows external clients to use basic
authentication
>and they don't need Log on Locally rights to do this

I've been testing this to see if I can reproduce it, but 
can't.   Everything I have ever done w/Basic Auth requires LOL,
regardless 
of the app running- it must be authenticated before the app kicks in 
anyway.  My guess is that there is something about your ISA -> Ex2k 
authentication that is authenticating these users on ISA, and building
an 
access token including some sort of group membership that the Exchange 
server recognizes as one that can LOL.  The way to test this is to go to

the Ex2k, and enable successful "logon events" and "account logon
events" - 
then have them logon externally- you will see the logon even in Ex2k,
and 
can examine the username and logon type... If it is Logon Type 2, you 
*know* that the user has been granted interactive logon (LOL) rights to
the 
box, and you can see what ISA is doing to cause this.

This is of particular interest to me, as if you indeed have some
membership 
structure where the ISA server will pass tokens to the internal Ex2k
server 
that allows them to impersonate LOL rights without actually having those

rights on the server itself, I would really like to know.  I see many 
configurations like this where Ex2k is on the DC, and I too want to
avoid 
giving the scrubs LOL rights for all the DC's.


>- For internal clients the ISA server won't pass Integrated Windows
>Authentication credentials.  The Exchange server won't allow internal
>clients to use basic authentication because it recognises that they're
>part of the domain and therefore tries to force Integrated Windows
>Authentication onto them which ISA won't pass.  How it recognises this
I
>don't know.  The IIS logs show that the URLs /Exchange,
/Exchange/username
>and /Exchange/username/Inbox all authenticate (HTTP status code 200)
but
>as soon as there's a redirect to /Exchweb/controls it fails (HTTP
status
>code 401).  Perhaps this is the stage at which active content is run
which
>determines that it's an internal client not an external one (though
this
>would have to be run on the server as there is no active content
fetched
>by the client at this stage)?  This is pure speculation...!

So, did you go to a client's IE config and add the FDQN to the Intranet 
sites, and then verify that "automatically logon only in intranet zone"
is 
selected?  That will ensure that the client first passes NTLM creds to
the 
site when accessed via the FDQN.  Can you check that and let us know?

Thanks

Tim


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