Windows Firewall may drop ICMP packets on a Windows XP SP2-based computer that has more than one network adapter

You are using a Microsoft Windows XP Service Pack 2 (SP2)-based computer that has more than one network adapter. On this computer, Windows Firewall may drop Internet Control Message Protocol (ICMP) packets when ICMP is enabled in the firewall configuration. In this scenario, Windows Firewall drops the ICMP reply message. Additionally, information that is similar to the following appears in the firewall log:

This problem occurs because an anti-spoofing rule drops packets if the following conditions are true:

• A multi-homed computer receives an ICMP echo request on one network adapter.
• The IP destination of the packet is the IP address of the other network adapter.

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 this specific problem. 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

No prerequisites are required.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfix.

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 tool in Control Panel.

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

For more information about how to obtain a hotfix for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base: For more information, click the following article number to view the article in the Microsoft Knowledge Base: