A Windows Vista-based or Windows Server 2008-based computer does not respond to 802.1X authentication requests for 20 minutes after a failed authentication

Consider the following scenario:

• You have a computer that is running Windows Vista or Windows Server 2008 in a network environment.
• You enabled 802.1X authentication for a network connection on the computer.
• The 802.1X authentication fails because of some transient error conditions.

In this scenario, the computer does not respond to any other authentication requests for 20 minutes. Therefore, the computer cannot access the network, or the computer only has limited access to the network.

This problem occurs because the system enters a blocking period that prevents the network from being overloaded with potentially unsuccessful authentications. During this blocking period, the system does not respond to EAPOL-Identity messages from the network access server. This blocking period is hardcoded to 20 minutes.

After you apply this hotfix, you can set a registry entry to configure the blocking period for failed 802.1X authentications. For more information, see the "Registry information" section.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running Windows Vista Service Pack 2 or Windows Server 2008 Service Pack 2.

For more information about how to obtain a Windows Vista service pack, click the following article number to view the article in the Microsoft Knowledge Base: For more information about how to obtain a Windows Server 2008 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix replaces the following hotfix:

Registry information

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: For wired networks

To use the new registry setting in a wired network, follow these steps:

1. Open Registry Editor. To do this, click Start
   , type regedit in the Start Search box, and then press ENTER.
2. Locate and then right-click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\dot3svc
3. Point to New, and then click DWORD Value.
4. Type BlockTime, and then press ENTER.
5. Right-click BlockTime, and then click Modify.
6. Click Decimal under Base.
7. In the Value data box, type an appropriate value for the blocking period, and then click OK. The value that you specify for this registry entry represents the number of minutes that the system waits before it retries a failed authentication. The default value is 20 and the valid range is 1 - 60. If you set this key to 0, it will not apply at all.
8. Exit Registry Editor.

For wireless networks

To use the new registry setting in a wireless network, follow these steps:

1. Open Registry Editor. To do this, click Start
   , type regedit in the Start Search box, and then press ENTER.
2. Locate and then right-click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\wlansvc
3. Point to New, and then click DWORD Value.
4. Type BlockTime, and then press ENTER.
5. Right-click BlockTime, and then click Modify.
6. Click Decimal under Base.
7. In the Value data box, type an appropriate value for the blocking period, and then click OK. The value that you specify for this registry entry represents the number of minutes that the system waits before it retries a failed authentication. The default value is�20�and the valid range is�1�-�60. If you set this key to�0, it will not apply at all.�
8. Exit Registry Editor.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Vista and Windows Server 2008 file information notes

Important Windows Vista hotfixes and Windows Server 2008 hotfixes are included in the same packages. However, only "Windows Vista" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows Vista" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The files that apply to a specific product, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.

  Version	Product	SR_Level	Service branch
  6.0.600 2 . 22xxx	Windows Vista and Windows Server 2008	SP2	LDR

• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 and for Windows Vista" section. MUM files and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintaining the state of the updated component. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows Server 2008 and of Windows Vista

For all supported x64-based versions of Windows Server 2008 and of Windows Vista

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

If you are using a wired connection for networking, this problem is temporarily resolved after you disconnect and then reconnect the network cable.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

Additional file information

Additional file information for Windows Vista and for Windows Server 2008

Additional files for all supported x86-based versions of Windows Vista and of Windows Server 2008

Additional files for all supported x64-based versions of Windows Vista and of Windows Server 2008