EAP-TLS machine authentication with ACS server

Discussion in 'Cisco' started by Mike, Oct 20, 2006.

  1. Mike

    Mike Guest


    I'm working on a limited 802.1x rollout, and was hoping to use Cisco
    ACS server as my RADIUS server / Authentication Server.

    Initial testing went fine using more basic EAP mechanisms, however when
    we started trying to use EAP-TLS, we ran into some problems. From what
    I can see in the Cisco ACS documentation, it's almost as if the ACS
    server requires an AD to talk to for authentication to complete - it
    can't simply rely on the a valid cert for authentication. Am I correct
    in understanding this? Unfortunately, the machines involved in this
    limited rollout have access to PKI infrastructure and a CA, but are not
    AD members - possibly an unusual set of circumstances.

    Two questions, assuming this reliance on an AD is real, and not just us
    misunderstanding what we're seeing:
    1 - Is this reliance on having an AD part of the IEEE EAP-TLS standard?
    This is the first I've seen of a requirement for a directory such as
    this in my readings about EAP-TLS.

    2 - If not, does anyone know of a product (maybe Steel-Belted RADIUS?)
    that doesn't have this requirement and can do the auth based solely on
    the validity of the cert?

    Cheers for any help,
    Mike, Oct 20, 2006
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  2. Hi Mike,

    You may wish to investigate:

    Cisco Secure ACS for Windows v3.2 With EAP-TLS Machine Authentication



    In the CiscoSecure ACS for Windows version 3.x, the CSUtil is not able
    to add other NAS vendors to the GENERIC EAP.dll

    This problem was first seen with CiscoSecure ACS for Windows version

    This issue occurs due to the presence of Cisco bug ID CSCec26584.

    CiscoSecure ACS for Windows currently supports EAP for only four RADIUS
    types ( Internet Engineering Task Force [IETF], Cisco IOS/PIX Firewall,
    Cisco VPN 3000, and Cisco Aironet ).

    The only way to add EAP support for other RADIUS types is through the

    When an imported RADIUS Vendor-specific Attribute (VSA) is used as the
    Network Access Server (NAS) type for 802.1x, EAP requests are rejected.

    The CiscoSecure ACS for Windows logs show that there is no association
    between X vendor and the GenericEAP.dll.


    As a workaround, verify that the IETF RADIUS NAS type is used.

    If so, everything works fine.

    If it is not used, create an association in the CiscoSecure ACS for
    Windows registry between the NAS vendor and the Generic EAP.dll, as

    1. Locate the NAS vendor number:

    HKEY_LOCAL_MACHINE\Cisco\CiscoAAAv3.2\NAS Vendors

    2. Add this number to this directory:



    Hope this helps.

    Brad Reese
    BradReese.Com - Cisco Repair
    1293 Hendersonville Road, Suite 17
    Asheville, North Carolina USA 28803
    USA & Canada: 877-549-2680
    International: 828-277-7272
    Fax: 775-254-3558
    AIM: R2MGrant
    BradReese.Com - Cisco Power Supply Headquarters
    www.BradReese.Com, Oct 20, 2006
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  3. Mike

    Mike Guest

    Hi Brad,

    Thanks for the reply, but as it turns out, the issue I was having is by
    design - this excerpt from a Cisco Press book tells me that Machine
    Authentication (machines performing 802.1x authentication in an
    automated fashio before login) is only supported for Windows systems,
    and requires an AD - there's no Machine Auth for local databases with
    ACS. I don't think I explained the problem properly before - I only got
    involved with the testing in a hands-on way yesterday.


    I'm not certain WHY it was designed like this, but there you go. I'm
    now trying to figure out if Machine Auth would work with Steel-Belted
    without a directory. I can see directory membership offering some
    additional security, but am surprised it's not optional.

    Mike, Oct 24, 2006
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