FlashFXP corrupting downloaded files (ProFTPd SSL/TLS server)

rainer · 11-17-2002, 06:08 PM

FlashFXP 2.0 build 902

FlashFXP is corrupting downloaded files from my ProFTPd server when the file is downloaded over a SSL or TLS connection. It downloads about 80% of the file, but the last bytes are simply gone. It doesn't happen always, but with 90% of the downloaded files. According to my experiences, very small files are not affected. Also, it happens only with DOWNLOADED files over a secure connection. Uploaded files are not affected at all. This problem also doesn't affect directory listings over SSL/TLS.

The server is running:
Linux 2.4.18
ProFTPd 1.2.7rc3

ProFTPd was compiled with:
OpenSSL 0.9.6g
mod_tls 2.0.4
(http://www.castaglia.org/proftpd/modules/mod_tls.html)

I haven't tested with other FTP clients, but this could be a problem with mod_tls ... not sure.

I tried changing the mod_tls related settings, but it didn't solve the problem. The proftpd.conf settings related to mod_tls currently are as follow:

-----------------------
TLSEngine on
TLSLog /usr/local/proftpd/etc/tls.log
TLSOptions NoCertRequest
TLSRandomSeed /usr/local/proftpd/etc/server.rnd
TLSRequired ctrl
TLSCACertificateFile /usr/local/proftpd/etc/ssl/ca.crt
TLSRSACertificateFile /usr/local/proftpd/etc/ssl/server.crt
TLSRSACertificateKeyFile /usr/local/proftpd/etc/ssl/server.key
-----------------------

FlashFXP doesn't report anything unsual when downloading the files, but when the download finishes, last bytes from the file are missing:

-----------------------
TYPE I
200 Type set to I.
PASV
227 Entering Passive Mode (< removed >).
RETR openssh-3.5p1.tar.gz
Negotiating SSL/TLS session...
150 Opening BINARY mode data connection for openssh-3.5p1.tar.gz (851486 bytes)
SSL/TLS negotiation successful...
SSL/TLS connection using cipher EDH-RSA-DES-CBC3-SHA (168 bits)
226 Transfer complete.
Transferred: openssh-3.5p1.tar.gz 831 KB in 34,48 (24,11 KBps)
Transfer queue completed
Transferred 1 file totaling 831 KB in 36,47 (24,11 KBps)
-----------------------

WinZip gives the following error when I try to open the file: "Error: unexpected end of file encountered".

The mod_tls log doesn't report anything unusual:

-----------------------
Nov 17 17:38:08 mod_tls/2.0.4[24898]: TLS/TLS-C requested, starting TLS handshake
Nov 17 17:38:10 mod_tls/2.0.4[24898]: TLSv1/SSLv3 connection accepted, using cipher EDH-RSA-DES-CBC3-SHA (168 bits)
Nov 17 17:38:16 mod_tls/2.0.4[24898]: Protection set to Private
Nov 17 17:38:17 mod_tls/2.0.4[24898]: TLSv1/SSLv3 data connection accepted, using cipher EDH-RSA-DES-CBC3-SHA (168 bits)
-----------------------

Let me know if you need any additional information.

PS: The above message is also being sent to the mod_tls author.

Regards,
Rainer