ISA Server 2004 blocks UDP traffic between two networks (915461)

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.

Action	Protocol
Denied Connection	Unidentified IP Traffic

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.

RESOLUTION

Service pack information

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

Hotfix information

ISA Server 2004 Standard Edition

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next ISA Server 2004 Service Pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

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

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

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.

File name	File version	File size	Date	Time	Platform
Comphp.dll	4.0.2165.606	167,192	12-Mar-2006	08:12	x86
Complp.dll	4.0.2165.606	63,768	12-Mar-2006	08:12	x86
w3filter.dll	4.0.2165.606	731,416	12-Mar-2006	08:12	x86
wspsrv.exe	4.0.2165.606	941,336	12-Mar-2006	08:12	x86

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.