When an FTP client computer downloads a large file by using
passive mode FTP, the download fails if it takes longer than 120
seconds.
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This problem may occur if the following conditions are true:
| • | The FTP client computer is configured to use the SOCKS
protocol. |
| • | The FTP client computer uses Microsoft Internet Security
and Acceleration (ISA) Server 2004 for outgoing passive FTP access. |
| • | The idle connection time-out value in ISA Server 2004 is
set to the default value of 120 seconds. |
Passive mode FTP uses an outgoing control channel connection and
an outgoing data channel connection. The file transmission occurs over the data
channel. The FTP control channel times out if the following conditions are
true:
| • | Data is not sent over the control channel during the
download operation. |
| • | A passive mode FTP file download takes longer than 120
seconds. |
Then, the FTP server stops the file download operation.
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To resolve this problem, install the hotfix package that is
described in the Knowledge Base article 923330, and then follow the steps that
are described in this article.
For more information, click the
following article number to view the article in the Microsoft Knowledge Base:
923330 (http://support.microsoft.com/kb/923330/)
Description of the ISA Server 2004 hotfix package: July 27, 2006
After you install this hotfix, run the following
Microsoft Visual Basic script to configure the SOCKS filter idle connection
time-out value to an appropriate value.
Note To determine the appropriate time-out value, use the following
equation:
Timeout (seconds) = file size / download speed * 1.2
For example, to determine the appropriate time-out
value to download a 200-megabyte (MB) file at 1 megabits per second (Mbps), use
the following equation:
200*8 / 1 * 1.2 = 1920 seconds
You must calculate the value to use individually.
Note The idle connection time-out setting helps free unused resources
so that resource-related issues do not occur. Therefore, we recommend that you
do not increase the time-out setting unnecessarily. If you use a time-out
setting that is less than the default 120 seconds, you can also create
unexpected issues.
To change the time-out setting, follow these
steps.
Note You must install the KB923330 hotfix package before you can
follow these steps.
| 1. | Click Start, point to All
Programs, point to Accessories, and then click
Notepad. |
| 2. | Copy and paste the following code into a new Notepad
document. Then, save the code to the ISA Server 2004 computer. To do this, use
a file name that has a .vbs extension such as
SetSocksIdleTimeout.vbs.<Script>
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' Copyright (c) Microsoft Corporation. All rights reserved.
' THIS CODE IS MADE AVAILABLE AS IS, WITHOUT WARRANTY OF ANY KIND. THE ENTIRE
' RISK OF THE USE OR THE RESULTS FROM THE USE OF THIS CODE REMAINS WITH THE
' USER. USE AND REDISTRIBUTION OF THIS CODE, WITH OR WITHOUT MODIFICATION, IS
' HEREBY PERMITTED.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' This script sets the idle connection time-out value for the SOCKS filter.
' The value is in seconds.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Sub SetSocksIdleTimeout()
' Create the root object.
Dim root ' The FPCLib.FPC root object
Set root = CreateObject("FPC.Root")
'Declare the other objects needed.
Dim array ' An FPCArray object
Dim Extensions ' An FPCExtensions object
Dim ApplicationFilters ' An FPCApplicationFilters object
Dim ApplicationFilter ' An FPCApplicationFilter object
Dim VendorSets ' An FPCVendorParametersSets collection
Dim VendorSet ' An FPCVendorParametersSet object
' Get references to the array object
Set array = root.GetContainingArray
On Error Resume Next
Set Extensions = array.Extensions
CheckError
Set ApplicationFilters = Extensions.ApplicationFilters
CheckError
Set ApplicationFilter = ApplicationFilters.Item("{25765C04-C80B-494C-914E-286297DB8C8E}")
Set VendorSets = ApplicationFilter.VendorParametersSets
Set VendorSet = VendorSets.Item( "{25765C04-C80B-494C-914E-286297DB8C8E}" )
VendorSet.Value("SessionIdleTimeoutSeconds") = 120 ' value in seconds to be set to desired value
ApplicationFilter.Save false, true
WScript.Echo "Done..."
End Sub
Sub CheckError()
If Err.Number <> 0 Then
WScript.Echo "An error occurred: 0x" & Hex(Err.Number) & " " & Err.Description
Err.Clear
End If
End Sub
SetSocksIdleTimeout
</Script>
|
| 3. | This script uses the default time-out value of 120 seconds.
Change the time-out value to the setting that you want, and then save the
script. |
| 4. | Double-click the .vbs file to run the script. |
After you run this script, the new time-out value is applied to
new SOCKS connections that are made through ISA Server 2004.
To
change back to the default time-out value, change the value back to 120 seconds
in the script, save the change, and then run the script again.
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To work around this problem, configure the FTP program to
send "keep-alive" commands on the FTP control channel.
For
information about whether the FTP program that you use supports this feature,
see the documentation for the FTP program.
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Microsoft
has confirmed that this is a problem in the Microsoft products that are listed
in the "Applies to" section.
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