Err Msg: 425 Can't Open Data Connection

ID: Q236001

The information in this article applies to:

SYMPTOMS

When you use an IIS 4.0 FTP server and Microsoft Proxy Server with the Server Proxy feature, the following error may be displayed on FTP clients:

425 Can't open data connection


CAUSE

This error occurs when two or more users, using a non-passive mode FTP client, are simultaneously accessing the same IIS 4.0 FTP server located behind the Proxy Server.


RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://support.microsoft.com/support/supportnet/default.asp
The English version of this fix should have the following file attributes or later:

   Date      Time                 Size    File name     Platform
   -------------------------------------------------------------
   06/16/99  07:53p               173,328 Wspsrv.exe    Alpha
   06/16/99  07:54p               262,416 Wspwsp.dll    Alpha
   06/16/99  07:54p                96,528 Wspsrv.exe    x86
   06/16/99  07:55p               141,072 Wspwsp.dll    x86

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:
Q154871 Determining If You Are Eligible for No-Charge Technical Support


STATUS

Microsoft has confirmed this to be a problem in Proxy Server 2.0.


MORE INFORMATION

After you apply the fix mentioned here, you will nedd to modify the Wspcfg.ini file located in the winnt\system32\inetsrv directory to allow FTP port 20 to be bound to the external interface of Proxy Server. This is due to a FTP functionality change in IIS 4.0 that forces the port to listen remotely and locally instead of just locally as in previous IIS versions.

The Wspcfg.ini file should look as follow: 


[Inetinfo]
ServerBindTcpPorts=21,20
LocalBindTcpPorts=20
Persistent=1
KillOldSession=1
ForceCredentials=1
After you make this change, stop the internal IIS computer where FTP is located by using the following steps:

1. From command prompt, type "net stop iisadmin /y".

2. Type "net start msftpsvc".

3. If Web publishing, type "net start w3svc".

4. Test for FTP functionality from the Internet.

Note: Wspsrv.exe should be installed on the Microsoft Proxy Server 2.0 computer and Wspwsp.dll should be installed on the Microsoft Proxy 2.0 Client.

Additional query words: 


Keywords          : 
Version           : winnt:2.0
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: July 16, 1999