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Home > Success Center > Serv-U Managed File Transfer & Serv-U FTP Server > Large file transfers abort after XX minutes without completing

Large file transfers abort after XX minutes without completing

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Updated April 27, 2017


This article provides information on the issue where a file transfer process aborts after xx minutes when setting up a secure IIS website using Microsoft's high security web hosting template.


All Serv-U versions


Using Microsoft's high security web hosting template for setting up a secure IIS website may experience problems with large file transfers. Large file transfers usually abort after a number of minutes even if they are active.
The cause of the problem is a change made in the template to the registry which sets an idle timeout for the TCP connections. The FTP protocol uses two connections. There is a command connection for issuing instructions to the server. Each time a data transfer is completed, it establishes a separate data connection. While on a data transfer, the command connection is idle which causes the disconnection. When the registry's idle timeout is already reached, it also triggers the command disconnection which disrupts any ongoing data transfer for any session as per the FTP standard.
The following is the registry key involved: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\KeepAliveTime The default is not to have the KeepAliveTime key at all, the template adds this. If a time-out is desired make sure the value is sufficiently large to accomodate all file tranfers (the value is in [ms]). Alternatively, an FTP client that periodically sends a command to the server during file transfers will also prevent the command connection from aborting.




Last modified
21:09, 26 Apr 2017