FTP client in TC uses unsupported HOST command (?)

[PMN]

Hi. I have problem with FTP connection from TC FTP client to Filezilla FTP Server on Windows 2008 R2 behind VPN firewall. It has nothing to do with passive or active mode, Windows firewall, open or closed ports. From native MS Windows FTP (remote FTP destination in File Explorer) it works fine. But everytime I try to connect to FTP from TC, the data flow stucks, typically something like that (from the TC FTP log):
....
230 Logged on
SYST
215 UNIX emulated by FileZilla
FEAT
211-Features:
MDTM
REST STREAM
SIZE
MODE Z
MLST type*;size*;modify*;
MLSD
UTF8
CLNT
MFMT
211 End
CLNT Total Commander (UTF-8)
.... and now connection stucks

The admin of our firewall (I think it is some CISCO ASA appliance) tell me, that the client (TC FTP client) probably use yet unsupported HOST command which is not in present valid RFC. The firewall is strictly set and deny such traffic. The current part of log looks like:

May 2 19:18:06 %ASA-5-303004: FTP HOST ftp.h command unsupported - failed strict inspection, terminating connection from internet:90.120.206.xxx/58185 to customers_dmz:10.5.100.11/21
May 2 19:18:06 %ASA-4-507003: tcp flow from internet:90.120.206.xxx/58185 to customers_dmz:10.5.100.11/21 terminated by inspection engine, reason - inspector drop reset.

I am quite sure, it is problem on TC side (maybe together with some Filezilla FTP Server feature), because of non problematic connection from other FTP clients.

Any suggestion, or comments? Is it a bug?

Thank you, Best regards PM

[ghisler(Author)]

Accrding to your log, it seems that your firewall hangs at CLNT command, not HOST command. The CLNT command is sent to tell the server the name of the ftp client. Turning on UTF8 fails on some servers when not sending the CLNT command. The reply to FEAT clearly indicates that the server supports CLNT.

Any suggestion, or comments?

Turn off the FEAT command, then TC will not send CLNT either because it doesn't know whether it is supported or not. You will need to set the encoding manually then, though.

Please add the following to wcx_ftp.ini under [General] :
PreventFEAT=1

[PMN]

It doesn't help. The TC FTP log now looks like:

PASS ***********
230 Logged on
SYST
215 UNIX emulated by FileZilla
CLNT Total Commander (UTF-8)
.... and stucks again

Nothing changed

PM

[ghisler(Author)]

CLNT is still sent when file name encoding is set to UTF-8 or automatic. Set it to ANSI in Ctrl+F - Edit (second page).

If your server defaults to UTF-8, you need to turn it off via "Send commands" field:
OPTS UTF8 OFF