Microsoft KB Archive/915461

= ISA Server 2004 blocks UDP traffic between two networks =

Article ID: 915461

Article Last Modified on 12/4/2007

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APPLIES TO


 * Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition
 * Microsoft Internet Security and Acceleration Server 2004 Standard Edition

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SYMPTOMS
A computer that is running Microsoft Internet Security and Acceleration (ISA) Server 2004 may block User Datagram Protocol (UDP) traffic between two networks.

Additionally, you may find entries that resemble the following in the ISA Server 2004 log files.

Notes
 * The Action column in the ISA Server 2004 log file marks the status of the connection.
 * The Protocol column lists Unidentified IP Traffic instead of listing the name of the actual protocol.
 * You may experience these symptoms for all UDP protocols. However, you typically experience them when you use UDP protocols such as Domain Name System (DNS) or NetBIOS.



CAUSE
This problem occurs because the ISA Server 2004 incorrectly processes the UDP requests.



ISA Server 2004 Enterprise Edition
To resolve this problem, obtain the latest service pack for ISA Server 2004 Enterprise Edition. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

891024 How to obtain the latest ISA Server 2004 service pack

ISA Server 2004 Standard Edition
A supported hotfix is now 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 service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or 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. To create a separate service request, visit the following Microsoft Web site:

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

Prerequisites
To apply this hotfix, you must have ISA Server 2004 Service Pack 2 (SP2) Standard Edition installed on the computer.

Restart requirement
You do not have to restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

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. 



WORKAROUND
To work around this problem, create an access rule and use the All outbound traffic option that lets all UDP protocols transfer from the destination to the source network. For example, if the ISA Server blocks traffic from a virtual private network (VPN) client to a DNS server that is located in another subnet, you must configure and apply the rule to let traffic transfer from the network of the DNS server to the network of the VPN client.

For more information about how to configure protocols for an access rule, see ISA Server 2004 online Help.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section of this article.



MORE INFORMATION
For more information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Keywords: kbbug kbfix kbqfe kbpubtypekc kbhotfixserver KB915461

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