User Guide for Cisco Secure Access Control Server - Stewing Home

Chapter 12 User Databases
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Windows User Database
User network authentication—ACS authenticates the user, allowing the user to have network
connectivity. If the user profile exists, the user database that is specified is used to authenticate the
user. While the user database is not required to be the Windows user database, most Microsoft
clients can be configured to automatically perform network authentication by using the same
credentials used for user domain authentication. This method allows for a single sign-on.
Note Microsoft PEAP clients may also initiate machine authentication whenever a user logs off. This feature
prepares the network connection for the next user login. Microsoft PEAP clients may also initiate
machine authentication when a user has selected to shutdown or restart the computer; rather than just
logging off.
ACS supports EAP-TLS, PEAP (EAP-MS-CHAPv2), and PEAP (EAP-TLS) for machine authentication.
You can enable each separately on the Windows User Database Configuration page, which allows a mix
of computers that authenticate with EAP-TLS or PEAP (EAP-MS-CHAPv2). Microsoft operating
systems that perform machine authentication might limit the user authentication protocol to the same
protocol that is used for machine authentication. For more information about Microsoft operating
systems and machine authentication, see Microsoft Windows and Machine Authentication, page 12-13.
The Unknown User Policy supports machine authentication. Computers that were previously unknown
to ACS are handled similarly to users. If the Unknown User Policy is enabled and an Active Directory
external user database is included on the Selected Databases list on the Configure Unknown User Policy
page, machine authentication succeeds; provided that the machine credentials presented to Active
Directory are valid.
On a computer that is configured to perform machine authentication, machine authentication occurs
when the computer started. Provided that the AAA client sends RADIUS accounting data to ACS, when
a computer is started and before a user logs in on that computer, the computer appears on the Logged-In
Users List in the Reports and Activity section. Once user authentication begins, the computer no longer
appears on the Logged-In Users List.
PEAP-based machine authentication uses PEAP (EAP-MS-CHAPv2) and the password for the computer
established automatically when it was added to the Microsoft Windows domain. The computer sends its
name as the username and the format is:
host/computer.domain
where computer is the name of the computer and domain is the domain to which the computer belongs.
The domain segment might also include subdomains, if they are used; so that the format may be:
host/computer.subdomain.domain
The usernames of computers that are authenticated must appear in the ACS internal database. If you
enable unknown user processing, ACS adds them automatically once they authenticate successfully.
During authentication, the domain name is not used.
EAP-TLS-based machine authentication uses EAP-TLS to authenticate the computer that is using a
client certificate. The certificate that the computer uses can be one installed automatically when the
computer was added to the domain or one that was added to the local machine storage later. As with
PEAP-based machine authentication, the computer name must appear in the ACS internal database in
the format contained in the computer client certificate and the user profile corresponding to the computer
name must be configured to authenticate by using the Windows external user database. If you enable
unknown user processing, ACS adds the computer names to the ACS internal database automatically;
once they authenticate successfully. It also automatically configures the user profiles that are created to
use the external user database in which the user was found. For machine authentication, this will always
be the Windows external user database.
User Guide for Cisco Secure Access Control Server 4.2
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