A large file download fails when an ISA Server 2004 SOCKS client computer or an ISA Server 2006 SOCKS client computer uses passive mode FTP

Article translations Article translations
Article ID: 923322 - View products that this article applies to.
Expand all | Collapse all

SYMPTOMS

When an FTP client computer downloads a large file by using passive mode FTP, the download fails if it takes longer than 120 seconds.

CAUSE

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 or Microsoft Internet Security and Acceleration (ISA) Server 2006 for outgoing passive FTP access.
  • The idle connection time-out value in ISA Server 2004 or in ISA Server 2006 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.

RESOLUTION

To resolve this problem, obtain the latest service pack for ISA Server 2004 and for ISA Server 2006.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
954258 How to obtain the latest Internet Security and Acceleration (ISA) Server 2006 service pack
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
891024 How to obtain the latest ISA Server 2004 service pack
After you install the appropriate service pack, 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 appropriate service pack 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-based computer or to the ISA Server 2006-based computer. To do this, use a file name that has a .vbs extension such as SetSocksIdleTimeout.vbs.
    
    ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    '
    ' 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
    
    
  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 or through ISA Server 2006.

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.

WORKAROUND

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.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

REFERENCES

For more information about how to install ISA Server hotfixes and ISA Server updates, click the following article number to view the article in the Microsoft Knowledge Base:
885957 How to install ISA Server hotfixes and updates

Properties

Article ID: 923322 - Last Review: March 26, 2009 - Revision: 2.0
APPLIES TO
  • Microsoft Internet Security and Acceleration Server 2004 Standard Edition
  • Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition
  • Microsoft Internet Security and Acceleration Server 2006 Standard Edition
  • Microsoft Internet Security and Acceleration Server 2006 Enterprise Edition
Keywords: 
kbtshoot kbexpertiseadvanced kbqfe kbprb KB923322

Give Feedback

 

Contact us for more help

Contact us for more help
Connect with Answer Desk for expert help.
Get more support from smallbusiness.support.microsoft.com