RE: ISA, Mailrealay and DMZ issues...

  • From: "Stefaan Pouseele" <stefaan.pouseele@xxxxxxx>
  • To: "'[ISAserver.org Discussion List]'" <isalist@xxxxxxxxxxxxx>
  • Date: Mon, 11 Feb 2002 21:35:57 +0100

Hi Michael,

the way you constructed your trihomed ISA configuration will never work.
Your main problem is that the DMZ subnet *must* be public ip-addresses and
your DMZ subnet has private ip-addresses. In a trihomed configuration ISA is
doing routing and packet filtering between external and DMZ interface, no
NAT/PAT is involved.

I suggest you take a look at:
-
http://support.microsoft.com/servicedesks/webcasts/wc110801/wcblurb110801.as
p very good presentation on the different DMZ scenario's
- the learning zone on www.isaserver.org

Hope this helps,
Stefaan

-----Original Message-----
From: michael [mailto:mwisch@xxxxxxxxxxxxxxxxx]
Sent: maandag 11 februari 2002 19:31
To: [ISAserver.org Discussion List]
Subject: [isalist] ISA, Mailrealay and DMZ issues...


http://www.ISAserver.org


I am trying to configure our email to go through our DMZ which currently
has a mail relay server, and I?m having a hard time getting email to go
out. This is how I would like it configured.

ISA SERVER = Trihomed   Mail Relay = 192.168.XX.XX  Exchange = 10.80.XX.XX
Public = 63.68.XX.XX
Private = 10.80.XX.XX
DMZ = 192.168.XX.XX

Email comes in and hits the ISA server (63.68.xx.xx) which has a SMTP
protocol rule pointing all incoming email to the Mail Relay server
(192.168.xx.xx). The Mail Relay Server than has a Remote Virtual SMTP
Server established on IIS to point all incoming email to the Smart Host
which is exchange(10.80.xx.xx). This configuration works fine for incoming
email, but I can?t seem to get things to work for outgoing email. When an
internal users tries to send email, it first hits the exchange box, which
has a SMTP connector  pointing to the Mail Relay. The problem is that the
mail relay server wants to send all incoming email to the exchange server,
this obviously becomes a routing problem. If I tell the exchange server to
use DNS instead of putting in the Mail relay server?s IP address, the
email goes out but avoids the mail relay all together, which defeats the
purpose of what I?m trying to do.

I have read a few articles and many of them mention the mail relay has to
have a public address, but this then opens up the Mail relay server for
intruders.

Thanks in advance.

------------------------------------------------------
You are currently subscribed to this ISAserver.org Discussion List as:
stefaan.pouseele@xxxxxxx
To unsubscribe send a blank email to $subst('Email.Unsub')



Other related posts: