SYMPTOMS
Internal SecureNAT and Internet Security and Acceleration Server (ISA) Firewall clients may not open the FTP data connection to an FTP server that is using passive mode FTP (PASV). The FTP server may return one of the following error messages:
426 Connection closed; transfer aborted.
-or-
425 Can't open data connection.
In some circumstances, the FTP client may seem to stop responding (hang) or time out. FTP clients that use active mode FTP (PORT) work without error.
RESOLUTION
You must install ISA Server Service Pack 1 (SP1) before you install the following hotfix.
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
How to Obtain the Latest Internet Security and Acceleration Server 2000 Service Pack
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 service pack that contains this hotfix.
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 about support costs, visit the following Microsoft Web site:
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.
The English version of this fix 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
-----------------------------------------------------
02-Apr-2003 11:52 3.0.1200.260 19,216 Ftpfltr.dll
This fix also applies to the French, German, Spanish, and Japanese versions of ISA Server.