RE: DMZ and AD Authentication

[jamesworld () intelligencia com]

Geoff,

I second what Shawn said.  If you can avoid it...don't do it.

If however, you are stuck with an order from up high.

Connect to the AD box thru the firewall via IPSEC.

If you use NIDS, however, this will blind it to any attack's that might 
come thru is the web server was compromised.

I would recommend using the Cisco Security Agent (formerly Okena) on the 
web server.

The other thing you could do is use a Cisco ACS server to front end the AD 
authentication and have the web server authenticate to the ACS via RADIUS 
or TACACS.  You will need to code the RADIUS integration (unless you can 
find it somewhere :-)

HTH,

-James

At 11:25 12/12/2003, Shawn Jackson wrote:

>         All you need LDAP access (TCP 389) to your Catalogue server.
> Even if you lock down your connection to the AD box, if someone
> compromises your IIS server they can gain a lot of information from your
> server. When we used this method with C# .Net we needed to have LDAP and
> Microsoft-DS (TCP 445) open to the server.
>
>         Honestly, I would advise against placing a server in the DMZ
> that will access any part of your AD infrastructure; it's just not
> secure enough. If you absolutely had to authenticate with AD I'd suggest
> creating a simple program (Webpage (ASP, CGI, and CF) or .Net
> Service/Remote App that would take two parameters (Username and
> Password) and return a value, then just parse that value to get your
> logon result. Place that app on a 'non-critical' server and it will be
> far more secure then accessing AD directly.
>
>         I can give you the code I use to access AD in C# and suggested
> implementation if you wish.
>
> Shawn Jackson
> Systems Administrator
> Horizon USA
> 1190 Trademark Dr #107
> Reno NV 89521
> www.horizonusa.com
>
> Email: sjackson () horizonusa com
> Phone: (775) 858-2338
>        (800) 325-1199 x338
>
> -----Original Message-----
> From: Geoff.Shatz () pchelps com [mailto:Geoff.Shatz () pchelps com]
> Sent: Friday, December 12, 2003 7:33 AM
> To: security-basics () securityfocus com
> Subject: DMZ and AD Authentication
>
> We are in a situation where we are currently planning the move of our
> web server from an externally hosted solution to hosting the web server
> in house. As part of this move we will be implementing a new internal
> application that will run on the web server that will require
> authentication based on Active Directory account info. Obviously this
> will require that the web server has the ability to communicate with the
> AD domain controllers. That being the case will it still be possible to
> place this web server on a DMZ or will the amount of open ports required
> between the DMZ and LAN for the required authentication process severely
> mitigate the benefits of placing the server in the DMZ in the first
> place? Any and all suggestions and or strategies to accomplish this in
> the most secure fashion are welcome and appreciated. Thanks!
>
> Geoff
>
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