Hi Daniel,

I managed to build ftp-multi-upload. I applied a few changes in a non-obtrusive way (at least I hope so ;-) to make it work on windows with Visual Studio.

To make it short: I could reproduce my problem (one channel stuck in passive mode) with the attached source on windows. But only on approx. every 20th test run. And I had to increase the number of files and their size to reproduce the error. Maybe we should implement a true dynamic way of faking a large number of files with a random size in a well-known range, to make this a real stress test.

I still used a remote server on our intranet.

Here's a WireShark log of the stuck channel:

---------------------------<snip>---------------------------
220 ProFTPD 1.3.0 Server (foo.bar.com) [::ffff:1.2.3.4]
USER user
331 Password required for user.
PASS password
230 User user logged in.
PWD
257 "/" is current directory.
CWD testfiles
250 CWD command successful
CWD awurf
250 CWD command successful
CWD FtpMultiUpload
250 CWD command successful
PASV
227 Entering Passive Mode (1,2,3,4,197,193).
TYPE I
200 Type set to I
STOR file01
150 Opening BINARY mode data connection for file01
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,193,250).
STOR file03
150 Opening BINARY mode data connection for file03
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,222,175).
STOR file04
150 Opening BINARY mode data connection for file04
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,197,106).
STOR file06
150 Opening BINARY mode data connection for file06
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,251,215).
STOR file11
150 Opening BINARY mode data connection for file11
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,219,142).
STOR file12
150 Opening BINARY mode data connection for file12
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,219,102).
STOR file13
150 Opening BINARY mode data connection for file13
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,208,143).
STOR file14
150 Opening BINARY mode data connection for file14
226 Transfer complete.
PASV
227 Entering Passive Mode (1,2,3,4,210,208).
STOR file16
150 Opening BINARY mode data connection for file16
PASV // <------- stuck here, no "226" for the previous transfer??
---------------------------</snip>---------------------------

If I should try with a local server on my Windows box, which server would you recommend?

Again, thanks a lot for your engagement.

Regards,
Andreas