Re: Putting MS servers behind firewalls

[<firewalladmin () bellsouth net>]

Hi Dilan:

Yes, you have a dilemma by putting MS servers behind an internal firewall. A few tips are the best I can offer, and 
forgive me if these are very general in nature and you may already know this:
1. MS uses the dangerous netbios ports extensively which you would need to allow inbound to the servers. These include 
TCP ports 135, 139, 445 and 1045 along with UDP ports 137 and 138. 

2. You need to allow the obvious DNS UDP 53 in/out for name lookups.

3. You need to allow inbound TCP 25 to the exchange server (at least).

4. I would allow the "established connection" outbound rule for the random port problem and see if it works. That way, 
a client connects to the mail server on an allowed port (25) and regardless of the reply port Exchange sets up, the 
firewall should know that is an "established" connection (also known as statefull inspection) and allow the traffic to 
pass.

5. Run TCPDump or Ethereal on your firewall to test the connections and see what else is going on that you may want to 
allow/disallow.

Hope this helps a little.
[:o)
Mark
============================================================
From: Dilan Walgampaya <Dilan () dpitl com>
Date: 2004/06/07 Mon AM 02:23:34 EDT
To: firewall-wizards () honor icsalabs com
Subject: [fw-wiz] Putting MS servers behind firewalls

Hi Wizards,

        I ran in to a problem putting Microsoft Servers behind a firewall. The 
users has to go through the FW to access the servers. The servers I 
wanted to put are on an AD domain. There were AD server, File server and 
an Exchange server. These servers need a large no. of services opened 
for proper operation. The worse is that exchange server work in a 
dynamic port setup where the server opens a random port for each 
different client. MS site has some registry edits that is supposed to 
correct this dynamic port setup issue. But when I tried these they did 
not work as per the document describes.

        Has anybody done this kind of a setup (with other than an ISA server). 
I am interested in doing this with Netscreen/Pix and Linux IPTables. Any 
help is appreciated.



Thanks in advance

Dilan
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============================================================


Mark F.
MCP, CCNA
"You can spend your life any way you want... But you can only spend it once."

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