Isolation Automation Exploration: Part I
Vista makes system-to-system IPSec authentication MUCH easier, if you know how to use it.
- By Greg Shields
Entire books have been written on network security and IPSec. Full of three-letter
acronyms for encryption technologies and concepts like "data integrity"
versus "data authorization," network security can make your head swim.
Before Windows Vista, setting up IPSec for system-to-system authentication
was complex, sometimes requiring hundreds of filters to secure traffic between
domain controllers while at the same time not inhibiting log-ons for older operating
systems. When a non-IPSec-aware client tried to connect to an IPSec-enabled
server, it often resulted in no connection at all.
Thankfully, with Windows Vista's improvements to IPSec, it all gets a lot easier.
It's now possible to create isolation groups that mandate machine-to-machine
authentication between sets of computers on your network.
So what's an isolation group? It's a way of using network rules to further protect
potentially open spots on your network. Let's say an administrator accidentally
shares a sensitive folder on your file server with Full Control permissions
to the Everyone group. Suddenly, all that sensitive data is immediately exposed
to anyone. If the data is on a human resources or other highly sensitive server,
you're really in trouble. Isolation domains leverage IPSec to ensure that any
machine attempting to connect to that share must authenticate via Kerberos before
it can transfer data. Think of an isolation domain as an extra access control
list (ACL) -- like NTFS and share permissions-but way down at the network level.
This extra computer-based ACL ensures that only the correct machines get access
to sensitive data and can only transfer that data securely.
Here's how it works. When you log in to a computer, your user account goes
through a Kerberos authentication process that ensures you are who you say you
are. Adding in an isolation group with IPSec means that any time your computer
tries to access another computer, the computer itself goes through an additional
authentication. If your computer successfully authenticates, then you can access
the data. This assumes of course that you then have the correct share and NTFS
rights. If your computer can't authenticate, the server either rejects the request
or allows a fallback to clear text communication.
All this was possible in Windows 2003, but IPSec was notoriously difficult
to set up. In Windows Vista, IPSec configuration has been merged with the Windows
Firewall and is now called Windows Firewall with Advanced Security.
In setting up an isolation group, four types of canned rules are available
or a custom rule can be created:
• Isolation: This will create a group of machines that are isolated
from other computers. This group can be for all machines in the Active Directory
Kerberos boundary, or can be an identified list of machines by IP address. Authentication
can occur for either inbound or outbound traffic, or both.
• Authentication Exemption: This will create a group of machines
exempt from any authentication requirements.
• Server to Server: This will create an authenticated connection
between two specific groups of computers. Think of this as the "one-to-one"
connection where the Isolation group would be the "many-to-many" connection.
• Tunnel: Like Server to Server, but usually used for bridging
traffic across the Internet, this will create an authenticated connection between
two computers utilizing an Internet-facing gateway server.
• Custom Connection: A connection that can be created using a
combination of the four different rules.
Next month I'll give step-by-step instructions for setting up an isolation
group on your network and go over some other tips on how to protect your network
from the inside out.
Greg Shields is a senior partner and principal technologist with Concentrated Technology. He also serves as a contributing editor and columnist for TechNet Magazine and Redmond magazine, and is a highly sought-after and top-ranked speaker for live and recorded events. Greg can be found at numerous IT conferences such as TechEd, MMS and VMworld, among others, and has served as conference chair for 1105 Media’s TechMentor Conference since 2005. Greg has been a multiple recipient of both the Microsoft Most Valuable Professional and VMware vExpert award.