The getpeername function may return an incorrect IP address when the AcceptEx function accepts a new Winsock connection through an I/O completion port on a computer that is running Windows Server 2008 or Windows Vista

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Symptoms

Consider the following scenario:

You create one or more I/O completion ports on a computer that is running Windows Server 2008 or Windows Vista.
You use the AcceptEx function to accept a new Winsock connection on the I/O completion ports.
You have an application that calls the getpeername function.

In this scenario, the getpeername function may return an incorrect IP address for the connection.

Cause

The Ancillary Function Driver (AFD) for Winsock (afd.sys) driver sends an asynchronous procedure call (APC) to the thread that calls the AcceptEx function when the getpeername function is called. However, the thread that calls the AcceptEx function exits before the queued APC is handled. Therefore, the queued APC is not processed and an incorrect IP address is returned.

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Resolution

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:

http://support.microsoft.com/contactus/?ws=support

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.

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the �Hotfix Request� page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.

Prerequisites

To apply this hotfix, the computer must be running one of the following operating systems:

Windows Vista Service Pack 1 (SP1)
Windows Vista Service Pack 2 (SP2)
Windows Server 2008
Windows Server 2008 Service Pack 2 (SP2)

Restart requirement

You must restart the computer after you apply this hotfix.

Registry information

You do not have to make any change to the registry.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.