You Cannot Connect to External FTP Sites by Using a WRQ Reflection FTP Client through ISA Server 2000

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SYMPTOMS

When you use a WRQ Reflection FTP client that is configured to use the SOCKS version 4 protocol, you may not be able to connect to external FTP sites through Microsoft Internet Security and Acceleration (ISA) Server 2000. The FTP client displays the following error message:

A connection can not be established. Please try again.

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CAUSE

The SOCKS version 4 Reflection FTP client spreads its SOCKS CONNECT request over two TCP segments. The built-in SOCKS application filter in ISA Server does not handle this correctly, and the SOCKS connection fails.

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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 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:

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

Prerequisites

To install this hotfix, you must have ISA Server Service Pack 1 (SP1) installed on your computer. For additional information about how to obtain the latest ISA Server service pack, click the article number below to view the article in the Microsoft Knowledge Base:

313139 (http://support.microsoft.com/kb/313139/EN-US/ ) How to Obtain the Latest Internet Security and Acceleration Server 2000 Service Pack

File Information

The English version of this hotfix has the file attributes (or later) 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.

Date         Time   Version       Size    File name
------------------------------------------------------
09-Oct-2003  15:22  3.0.1200.295  34,064  Socksflt.dll

This fix also applies to the French, German, Spanish, and Japanese versions of ISA Server.

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