Truth be told this is actually a VERY common configuration (opening LDAPS over 
the Internet to a set of remote IPs). I've seen it in many many large orgs. 
It's not the cleanest but it works.

Thanks,
Brian Desmond
[email protected]<mailto:[email protected]>

c - 312.731.3132

From: Mayo, Bill [mailto:[email protected]]
Sent: Friday, November 20, 2009 2:13 PM
To: NT System Admin Issues
Subject: RE: Cisco Question

I could possibly live with the SSL encryption of the traffic if it was a short 
term situation.  You could probably make an argument that the VPN connection 
isn't signficantly more secure than LDAP over SSL, but the VPN connection gives 
you an extra layer of authentication.

Is it an option to just have a secondary authentication on their box?  I know 
and understand that multiple usernames/passwords isn't desirable, but I 
personally haven't run into a situation where a 3rd party wanted to 
authenticate against our domain from their server.

I'm sure that there are folks that know more than I do, but I would offer the 
following potential security issues (that come to mind at the moment):

  *   IP addresses can be spoofed and someone could run an attack against your 
DC.  Depending your lockout policies, they could detect usernames/passwords 
and/or lockout accounts.  They could also do some kind of DOS attack.
  *   A disgrunted employee at the 3rd party could take action to capture your 
usernames/passwords (at least there is some possible remedy for that).  This 
one is a potential issue no matter how you secure the connection.
The bottom line is that you are opening a port directly to a domain controller 
over the internet.  Make sure you point out the potential issues.  If the 
powers that be decide to go-ahead, you have at least done your duty to warn 
them.

________________________________
From: Chyka, Robert [mailto:[email protected]]
Sent: Friday, November 20, 2009 2:56 PM
To: NT System Admin Issues
Subject: RE: Cisco Question
Thanks for the great points!!  So if we can't get a VPN setup, would you fight 
to kill the project or would you trust the SSL cert encryption?

________________________________
From: Mayo, Bill [mailto:[email protected]]
Sent: Friday, November 20, 2009 2:54 PM
To: NT System Admin Issues
Subject: RE: Cisco Question

I think opening port 389, even restricted by IP, over the internet is a 
non-starter.  That means that the logon credentials are being sent over the 
internet in the clear.  Make sure you insist on the SSL variant, although I 
would note that I personally wouldn't even be happy about that.  I would much 
prefer some kind of VPN setup directly to the box, if possible.

________________________________
From: Don Ely [mailto:[email protected]]
Sent: Friday, November 20, 2009 2:27 PM
To: NT System Admin Issues
Subject: Re: Cisco Question
create an ACL allowing only access from their IP address to your NAT'd address. 
 Also, I'd put an SSL cert on your AD servers and use 636 instead...
On Fri, Nov 20, 2009 at 11:25 AM, Chyka, Robert 
<[email protected]<mailto:[email protected]>> wrote:
Hello,

We have a Library Catalog server that is hosted by the company that we 
subscribe to their databases.  It is a server dedicated to our school, but 
hosted in their data center.  They need to have LDAP access from their 
outsourced box to our internal AD Controllers for LDAP authentication for our 
users to the database server.

Our AD servers sit behind a ASA Firewall.  How would I set up the rule to allow 
port 389 to be open for the IP address of the outsourced server?

Any help is greatly appreciated.

Bob






















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