FTP Server dropping connection before transfer is completed

Question : FTP Server dropping connection before transfer is completed


I’ve been trying to find out why this problem is happening.  The thing is, one client tries to upload a file to this Windows 2003 FTP Server (IIS 6).  The connection is made, the transfer begins, and some time before the transfer is complete, the connection drops.  The FTP log reads “closed – 421 121” in the middle of the transfer.  I’ve tried the same with two different clients (command line FTP and a Mainframe FTP client) with the exact same results.  Google says that I’m not the only one with this problem, yet I couldn’t find a single straight answer for this.  It is not a passive/active issue, as the connection is made and the transfer runs to a point (the file some times even get created in the server), and some times the file transfer completes without problems!  This, of course, also rules out any firewall issue.



Solution : FTP Server dropping connection before transfer is completed

Burried in this link:

It talk about the 421 121 error.  Apparently the 121 is an error message number from the "network" and means:

     "The semaphore timeout period has expired."

What you need to do is look at the ftp log and see how much time has passed between the last command processed and the "closed 421 121" message.

I assumed that in the client side stuff you posted that the time between the 150/426 and the stats message with just a few seconds.  How much time did pass between the 150 and 426 message?