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Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
When you use the Microsoft Internet Security and Acceleration (ISA) Server 2000 Web Proxy service to anonymously connect to an FTP site, you may receive the following HTTP - 502 error message:
The page cannot be displayed
There is a problem with the page you are trying to reach and it cannot be displayed.
Please try the following:
Click the Refresh button, or try again later.
Open the ftp site home page, and then look for links to the information you want.
If you believe that you should be able to view this directory or page, please contact the Web site administrator by using the e-mail address or phone number listed on the ftp site home page.
HTTP 502 - Bad gateway Internet Security and Acceleration Server
If you use an FTP client program that does not use the Web Proxy service to access this FTP site (for example, if you use FTP.exe), you can access the FTP site successfully.
This problem occurs because when you connect to an FTP server that requires user authentication for anonymous connections, and no credentials are defined in the initial connection URL, ISA Server uses predefined credentials in the following format:
User name: anonymous Password: proxyuser@
However, if the FTP server is configured so that it must have specific information in the domain portion of the credentials (the portion after the "at" (@) sign), the authentication is unsuccessful and ISA Server returns. For example, the FTP server may require a credential that is similar to the following credential:
an HTTP - 502 error message.
Note The Web Proxy service does not support non-anonymous FTP servers unless you include the credentials in the URL.
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.
You must install ISA Server Service Pack 1 (SP1) before you install this hotfix.
For additional information about how to obtain the latest ISA Server service pack, click the following article number to view the article in the Microsoft Knowledge Base:
313139 How to Obtain the Latest Internet Security and Acceleration Server 2000 Service Pack
You must restart the W3Proxy service to apply the changes after you install this hotfix.
Hotfix Replacement Information
This hotfix does not replace any other hotfixes.
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 ------------------------------------------------------- 30-Sep-2003 17:09 3.0.1200.293 103,184 Msphlpr.dll 30-Sep-2003 17:09 3.0.1200.293 178,448 Mspadmin.exe 30-Sep-2003 17:08 3.0.1200.293 392,976 W3proxy.exe 30-Sep-2003 17:09 3.0.1200.293 299,280 Wspsrv.exe
Note This hotfix does not contain special code for other language editions of ISA Server 2000.
Windows Registry Information
Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.
After you install this hotfix, you must add the following Windows registry value:
Right-click Parameters, point to New, and then click String Value.
Right-click WebProxyFtpClientPassword, and then click Modify.
In the Value data box, type:
Quit Registry Editor, and then restart the W3Proxy service.
Microsoft has confirmed that this is a problem in Microsoft Internet Security and Acceleration Server 2000.
Because of the way that most Web browser programs transform the FTP site request to canonical form, you cannot specify your credentials in the initial request URL to work around this problem. For example, to work around this problem, you cannot type a request that is similar to the following request:
In this scenario, the Web browser program interprets the first instance of the "at" (@) sign to indicate where the user credential portion of the request ends with the remainder of the request interpreted as the actual URL. As a result, the request is not successful because the Web browser incorrectly interprets the URL as the following URL: