iis ftp: Cannot FTP more than 4 MB between two Win2003 SP 1 machines... -- iis ftp

Cannot FTP more than 4 MB between two Win2003 SP 1 machines...

Taed Wynnell
3/9/2006 3:36:51 PM

iis ftp:

I have the weirdest problem which basically boils down to that I can't FTP
files larger than 4 MB to/from a certain FTP server from certain machines,
but larger files work with other servers and other clients.

I have an FTP server running Windows Server 2003 SP 1. I have a client that
is also running Windows Server 2003 SP 1.

If I FTP from the client to the server a file that is 4 megabytes or
smaller, the transfer works fine. If the file is even larger (I tested with
a variety of files, including one that is 4 MB plus 1 byte), then the
transfer fails. The transfers actually fail with both PUT and GET in
similar ways.

But the way it "fails" is weird. The file will actually show up on the
server in tact, but the client thinks that the transfer failed because it
just sees "connection closed by remote host". I ran a packet sniffer and
the transfer actually looked fine, and the server actually did send the text
"226 Transfer complete.", but maybe it didn't do something else that the
client is expecting?

My testing data points are so weird that I just don't know where to go with
it... It seems to say that it's just a problem with those two specific
machines (or clones of them), but not with Win2003 in general or with either
machine alone.

-- The client can transfer large files to other FTP servers without a
problem, including other Win2003 servers.
-- The server can accept large files from other clients without a problem,
including other Win2003 clients.
-- Other clients that were "cloned" from the same original hard drive also
have the problem when FTPing to that one server.
-- The problem happens both when transmitting and receiving large files.
-- The problem happens both local to the server and over the Internet.
-- The client and server are running Win2003 SP 1, so the hotfixes for the
FTP 2 MB problem are included there.
-- The server is running NTFS, so the FAT limitation of 4 MB files isn't
there. And the files do transfer in tact, so it's seemingly not a file
system issue.
-- I tried installing KB899679 (the newest FTP.EXE that I could find) to the
client, but that made no difference.
-- I used Internet Explorer 6.1 on the client to do the FTP, but same
result. That seems to imply that it's not a problem with FTP.EXE.
-- I have another program that uses FTP via the SDK, and that also has the
same problem.
-- But I transferred the file via shared disks with Remote Desktop, and that
worked fine. That implies a problem with FTP in general, not something with
the network.
-- It is 100% reproducible between those two machines (or clones of them).
-- The IIS FTP logs on the server are identical between the good and bad
cases, so it doesn't seem to recognize the problem.
-- I've searched the Microsoft Premier KnowledgeBase and Google, but came up
with nothing.

Does anyone have any theories or suggestions?

Thanks in advance for any assistance!