IIS 5 & IIS 6
FTP Server incorrectly resuming and corrupting files
Last post Apr 21, 2008 06:56 AM by bszom
Mar 05, 2008 06:05 AM|bszom|LINK
I have a fairly simple IIS FTP site set up on a Windows Server 2003 SE (SP2) box - a virtual with my hosting company, to be precise.
I've opened a few ports in the Windows Firewall to allow for passive mode transfers, and this is working as expected.
The problem I'm experiencing is that the FTP server seems to incorrectly resume file downloads. Instead of resuming at the point requested by the client, it is as if the transfer is restarted from the beginning of the file, thus causing corruption.
It is easily noticed when one resumes a large MP3, for example, because the album/set starts again from the beginning at the point where the file was resumed. Another symptom is that my FTP client will continue downloading past 100%, and create a file that
is larger than the original on the server.
I've tried a number of different FTP clients, without success.
Can anyone point me in the right direction as to what to check, etc.?
Apr 17, 2008 03:35 AM|JaroDunajsky|LINK
Apr 21, 2008 06:56 AM|bszom|LINK
I don't keep logs for my FTP clients but I do generally keep an eye on the exchange between server and client in terms of commands. All of the clients which I tried sent a regular REST command with the byte offset at which to resume, yet IIS "resumed" from
the beginning of the file.
I have since switched to dedicated FTP server software and the problem went away. Go figure.