Daylight Saving Time and Mobility XE

Technical Note 2217

Last Reviewed 14-Feb-2007
Applies to:
Mobility XE
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Summary

The U.S. Energy Policy Act of 2005 extended Daylight Saving Time (DST) in the U.S. by approximately four weeks. As a result, beginning in 2007, DST will start three weeks earlier on March 11, 2007, and end one week later on November 4, 2007, resulting in a new DST period that is four weeks longer than previously observed. Unless certain updates are applied to your computer, it is possible that the time zone settings for your computer's system clock may be incorrect during this four week period. In certain situations this could prevent a Mobility client from authenticating to a Mobility server.

For more information, see Microsoft's Daylight Saving Time Help and Support Center.

Daylight Saving Time, NTLMv2, and Mobility XE

Mobility XE receives all its time- and clock-related data from the Windows operating system. If Mobility is configured to use NTLMv2 for authentication, a client device is not allowed to authenticate to the server unless its system clock is within 30 minutes of the server's system clock. You will need to apply a patch from Microsoft to your Mobility server machine(s) and your client devices to ensure both systems are updated with the new DST start and end dates.

Important: If your Mobility server is a member of a domain, you must patch the domain controller as it is the source of the Mobility server's date and time settings.

Microsoft patch information is available from the link above.

Workaround

If you are not able to patch all your server and client machines before the new DST start date takes effect, you can work around the 30-minute limitation by enabling the Advanced Server Setting "Authentication - NTLM Automatic Time Sync". Follow these steps to configure the setting:

1. In the Mobility XE Server console, open the Server Settings page.

2. Enable Advanced Settings. (Refer to Technical Note 2158 for instructions on enabling Advanced Settings.)

3. Select the Authentication - NTLM Automatic Time Sync setting.

4. Check the Synchronize client time checkbox, and click Apply.

Impact of the workaround

Selecting the Synchronize client time checkbox allows the Mobility client to modify the system date and time it reports to the Mobility server in the authentication request so authentication can proceed. It does not change the system time on the client device.

Note: NetMotion Wireless does not recommend leaving this setting enabled for any longer than is absolutely necessary. The setting bypasses a security feature of NTLMv2 that mitigates replay attacks.

Related Information

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