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Bitlocker and Wake on Lan RRS feed

  • Question

  • Hi,
    when we start our vista clients by wake on lan we get the prompt for Bitlocker recovery password. Is there anything we can do about it? I can't find exact information about which TPM or Bitlocker-check to have to be disabled to prevent this behaviour.
    After another manual reboot and physical presence on the machines they boot without a problem.

    Any clues?

    Thanks,
    Michael
    Thursday, June 4, 2009 9:35 AM

Answers

  • Hi Michael,

     

    The problem appears to be a different boot order occurring based on how the platform is turned on. If the boot order is different, the system boot measurements will be different and BitLocker will force the user to provide the recovery key when using a BitLocker key protector which includes the TPM.

    Based on my research and experiences, the problem can be solved setting the Wake On LAN option to “Follow Boot Order” in BIOS.

     

    Note: The BIOS options may be different on various platform, refer to your motherboard manual or vendor for more information.

    For example, the BIOS options under System Configuration\Built In Device Options\Wake On LAN are:

    · Disabled
    · Boot to Network
    · Follow Boot Order

    If the option “Boot to Network” is selected, when the platform is awoken from the LAN, it will boot to the network, potentially fail and then boot to the hard drive by following the normal boot order. This results in a different measurement on a conventional BIOS system then following the normal boot order alone. The different measurement results in the message from BitLocker that the system boot information has changed and BitLocker forces the customer to enter the recovery key (or reboot).

    Configuring the setting to “Follow Boot Order” will cause the same boot sequence BitLocker used when it was turned on. This will cause BitLocker to boot normally.

     

    Note: If the “Follow Boot Order” option is not an available option of Wake On LAN in your BIOS, you may need contact the vendor to update the latest BIOS.

     

     

    Reference:

     

    What causes BitLocker to start into recovery mode when attempting to start the operating system drive?

    http://technet.microsoft.com/en-us/library/ee449438(WS.10).aspx#BKMK_examplesosrec

     


    Best regards,

    Tony Ma
    • Marked as answer by MSimonis Wednesday, February 23, 2011 9:29 AM
    Wednesday, August 11, 2010 6:47 AM