ISA Server Web Proxy Does Not Append the Domain Name Suffix to the Credentials That Are Passed to an FTP Server (823359)

SYMPTOMS

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.

CAUSE

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:

proxyuser@example.com

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.

RESOLUTION

Hotfix Information

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, Microsoft recommends that you wait for the next ISA Server 2000 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 phone 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

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

Restart Requirement

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.

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
   -------------------------------------------------------

   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:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3Proxy\Parameters

Value name: WebProxyFtpClientPassword
Value type: REG_SZ
Value data: user@example

To do this, follow these steps:

Click Start, click Run, type regedit in the Open box, and then click OK.
Locate, and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3Proxy\Parameters
Right-click Parameters, point to New, and then click String Value.
Type:
WebProxyFtpClientPassword
Right-click WebProxyFtpClientPassword, and then click Modify.
In the Value data box, type:
user@example
Click OK.
Quit Registry Editor, and then restart the W3Proxy service.

MORE INFORMATION

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:

ftp://anonymous:user@example.com@ftp.example.com

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:

example.com@ftp.example.com