Educause Security Discussion mailing list archives
Re: AD across multiple campuses
From: Scott Weyandt <scott.weyandt () MORANTECHNOLOGY COM>
Date: Fri, 20 Feb 2009 17:13:17 -0600
It is a fact that true security boundaries exist only between forests. So, if you need to isolate the 35 institutions such that "Authenticated Users" at Institute A are not able to access anything that's not explicitly ACLed in Institute B, then separate forests are necessary. However, 35 forests is a lot of management overhead and 100 locations and 100K seats is NOT an issue from a scale perspective for a forest. Accordingly, individual forests should only be recommended (or implemented) where you want to eliminate all access between domains except for where access is explicitly provided via ACLs. In most cases this isn't required. As far as the original post about the network numbering. You can definitely do domain controller replication over the Internet. The best way to do it is with IPSec tunnels (directly between DCs even, http://technet.microsoft.com/en-us/library/bb727063.aspx). You shouldn't need to configure the AD (or network) topology such that every client needs to be able to talk to every DC. A lot of organizations simply can't do this. It's fine to run AD traffic over mixed use links. In fact, our lead MS Architect, Brian Desmond is speaking about this at DEC in a few weeks. Brian is also the author of O'Reilly's latest version of Active Directory (http://oreilly.com/catalog/9780596520595/?CMP=AFC-ak_book&ATT=Active+Direct ory). Obviously he knows a lot more about this than I do, so if you have any additional questions about this send me a personal email and I will give you his contact information. He's always happy to answer questions and can frequently found on the new Microsoft Higher Ed listserv: http://www.windows-hied.org/ Thanks. ***************************************************************** Scott Weyandt, PhD Director, Security and Infrastructure Planning Moran Technology Consulting 877-214-2980 (Voice & Fax) Website: www.MoranTechnology.com ***************************************************************** -----Original Message----- From: The EDUCAUSE Security Constituent Group Listserv [mailto:SECURITY () LISTSERV EDUCAUSE EDU] On Behalf Of John Ladwig Sent: Friday, February 20, 2009 3:24 PM To: SECURITY () LISTSERV EDUCAUSE EDU Subject: Re: [SECURITY] AD across multiple campuses As I recall, MS AD engineers recommended to our large (100 location, 35 institution, ~100k-node) system that we *not* attempt a single forest, as interforest boundaries are the only place where security can be applied. The recommendation they whiteboarded was for a coordinated user namespace, and tie per-institution forests together using a systemwide LDAP. We've not attempted to build that, yet, and MS large-scale advise may have changed in the last... 16 months. Also, in our system, we are pretty federal; each institution has responsibility for its own IT, and then there's another Systemwide IT function for enterprise apps, and the wide-area network. Suggestions made for us should be compared carefully to your local environment. -jml
Jeff Kell <jeff-kell () UTC EDU> 2009-02-20 15:17 >>>
We are again revisiting a "single forest" integration of AD across multiple campuses in the system, and the inevitable pros/cons and issues are starting to roll in. I'm interested in any information / pointers / feedback / suggestions from other sites that have done or tried this approach. Specifically with regard to routing/addressing and overall security (not just the AD components)... Each campus is essentially a separate network entity now, no private links / leased lines / hocus-pocus. We have our individual internet[2] providers. Most sites are using RFC-1918 addresses internally, to varying degrees, some are required to (lack of public IPs). The RFC-1918 space currently overlaps. Each site will have it's own domain (tree?) but there is a desire for cross-site replication and redundancy of domain controllers. The current "desire" from the design group (I'm certainly no AD guru, I'm network/security) states that each user on each campus must have a globally unique IP address, such that "any" user at "any" campus can authenticate to "any" of the domain controllers. Some us will have to renumber our 1918 space, but it is doable. Private links (either leased, site-to-site VPN, or MPLS-provider private vlans) have been proposed to route the AD client/domain traffic within the system. Having survived Blaster, Slammer, Nachi, Conficker (so far), and other network nightmares exploiting Microsoft infrastructure in the past, I'm very concerned about having one big flat system-wide routed domain. Restricting the "private" links to "only" AD-related traffic seems troublesome as well (firewalls, policy routing, etc), but perhaps not insurmountable. There is a great deal of existing inter-campus traffic (operating through traditional NAT/firewalls) for centralized SAP/R3, video traffic, distance learning, distributed printing, and other cases. Much of this is freely intermixed on networks that would also have AD clients/servers. Is all of this really necessary to provide the desired result? Is anyone doing this over "the public internet" ? Can DC-to-DC replication happen across NAT, without all this other infrastructure/exposure? Can client-to DC authentication happen across NAT? Is there some way to keep the existing site network/routing autonomy? Jeff Kell University of Tennessee at Chattanooga
Current thread:
- AD across multiple campuses Jeff Kell (Feb 20)
- <Possible follow-ups>
- Re: AD across multiple campuses John Ladwig (Feb 20)
- Re: AD across multiple campuses Dexter Caldwell (Feb 20)
- Re: AD across multiple campuses Michael Sinatra (Feb 20)
- Re: AD across multiple campuses Scott Weyandt (Feb 20)
- Re: AD across multiple campuses Dexter Caldwell (Feb 22)
- Re: AD across multiple campuses John Ladwig (Feb 23)