FTP: file transfers are incomplete

[Tobias Stein]

Hi community,

Recently, I observed a strange behavior uploading files to my servers via FTP (over TLS). I'm using a passive FTP connection. Listing directories, downloading files and so on works well. Except the fact that I cannot upload files larger than 131072 bytes. Filezilla as my FTP client in this scenario throws an error message, disconnects and then automatically resumes the upload. Obviously, a small part of the file has been uploaded so a new window pops up asking me what to do.

I remember that I had some issues connecting to the FTP server so I defined the passive port range and opened the ports in Plesk as well.

Components:
I'm running Plesk 12.5.30 #18
# rpm -qa | grep proftp
psa-proftpd-1.3.5a-cos6.build1205150826.18.x86_64
CentOS release 6.7 (Final)

Logs:
Unfortunately, they don't provide error messages nor do they give a hint what might cause the issue.

What I already checked prior to this posting:
- I disabled the firewall completly -> problem still exists
- I established a connection using plain FTP -> uploading larger files was working.

I was looking into TLS settings but there is not much content in /etc/proftpd.d/ssl.conf except that SSLv2 and SSLv3 are deactivated.
The weird thing is that I can't remember touching any of the proftpd files (except the passive port range). On another server running on CentOS 7 with a plain Plesk 12.5.30 installation I have the same issue.

Best regards,
Tobias

 

[Tobias Stein]

I digged a bit deeper and found out that uploading files with lftp does work.
The logfiles on the server contain the following lines:

Filezilla: File upload does not work
# tail -fn0 /var/log/plesk/ftp_tls.log
2016-01-10 13:25:24,909 mod_tls/2.6[26739]: TLS/TLS-C requested, starting TLS handshake
2016-01-10 13:25:25,011 mod_tls/2.6[26739]: client supports secure renegotiations
2016-01-10 13:25:25,011 mod_tls/2.6[26739]: TLSv1.2 connection accepted, using cipher DHE-RSA-AES128-SHA (128 bits)
2016-01-10 13:25:25,245 mod_tls/2.6[26739]: Protection set to Private
2016-01-10 13:25:25,454 mod_tls/2.6[26739]: starting TLS negotiation on data connection
2016-01-10 13:25:25,604 mod_tls/2.6[26739]: TLSv1.2 data connection accepted, using cipher DHE-RSA-AES128-SHA (128 bits)
2016-01-10 13:25:28,623 mod_tls/2.6[26553]: starting TLS negotiation on data connection
2016-01-10 13:25:39,644 mod_tls/2.6[26741]: TLS/TLS-C requested, starting TLS handshake
2016-01-10 13:25:39,754 mod_tls/2.6[26741]: client supports secure renegotiations
2016-01-10 13:25:39,754 mod_tls/2.6[26741]: TLSv1.2 connection accepted, using cipher DHE-RSA-AES128-SHA (128 bits)
2016-01-10 13:25:39,963 mod_tls/2.6[26741]: Protection set to Private
2016-01-10 13:25:40,169 mod_tls/2.6[26741]: starting TLS negotiation on data connection
2016-01-10 13:25:40,322 mod_tls/2.6[26741]: TLSv1.2 data connection accepted, using cipher DHE-RSA-AES128-SHA (128 bits)
2016-01-10 13:25:40,665 mod_tls/2.6[26741]: starting TLS negotiation on data connection

lftp: File upload does work
# tail -fn0 /var/log/plesk/ftp_tls.log
2016-01-10 13:26:16,262 mod_tls/2.6[26759]: TLS/TLS-C requested, starting TLS handshake
2016-01-10 13:26:16,482 mod_tls/2.6[26759]: client supports secure renegotiations
2016-01-10 13:26:16,482 mod_tls/2.6[26759]: TLSv1.2 connection accepted, using cipher DHE-RSA-AES128-SHA (128 bits)
2016-01-10 13:26:17,075 mod_tls/2.6[26759]: SSL/TLS required but absent on data channel, denying STOR command
2016-01-10 13:26:17,125 mod_tls/2.6[26759]: Protection set to Private
2016-01-10 13:26:17,262 mod_tls/2.6[26759]: starting TLS negotiation on data connection
2016-01-10 13:26:17,425 mod_tls/2.6[26759]: TLSv1.2 data connection accepted, using cipher DHE-RSA-AES128-SHA (128 bits)

 

[cookkoo]

Hello, I have the same issue. And as i am not a programmer. Please help to explain for, How,What and Where you fix the issue from your information above ? Thank you.

 

[trialotto]

Hi community,

Recently, I observed a strange behavior uploading files to my servers via FTP (over TLS). I'm using a passive FTP connection. Listing directories, downloading files and so on works well. Except the fact that I cannot upload files larger than 131072 bytes. Filezilla as my FTP client in this scenario throws an error message, disconnects and then automatically resumes the upload. Obviously, a small part of the file has been uploaded so a new window pops up asking me what to do.

I remember that I had some issues connecting to the FTP server so I defined the passive port range and opened the ports in Plesk as well.

Components:
I'm running Plesk 12.5.30 #18
# rpm -qa | grep proftp
psa-proftpd-1.3.5a-cos6.build1205150826.18.x86_64
CentOS release 6.7 (Final)

Logs:
Unfortunately, they don't provide error messages nor do they give a hint what might cause the issue.

What I already checked prior to this posting:
- I disabled the firewall completly -> problem still exists
- I established a connection using plain FTP -> uploading larger files was working.

I was looking into TLS settings but there is not much content in /etc/proftpd.d/ssl.conf except that SSLv2 and SSLv3 are deactivated.
The weird thing is that I can't remember touching any of the proftpd files (except the passive port range). On another server running on CentOS 7 with a plain Plesk 12.5.30 installation I have the same issue.

Best regards,
Tobias

@Tobias,

Did you resolve your issue yet?

I see that you have enable passive ports, but what kind of range did you use?

It can be the case that one of the ports in your passive port range is also used by another process, which case seems to be suggested by the "SSL/TLS required but absent on data channel" in the logs (after all, any service, configured to use a port without SSL/TLS requirements in the range of your passive ports, could cause this behaviour).

Anyway, just let me know whether the issue has been resolved.

Regards......