FTP connection broken, empty window, no content, no parent directory

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ackuxacky
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FTP connection broken, empty window, no content, no parent directory

Post by *ackuxacky »

Since few months I'm experiencing an issue with FTP connection on TC 9.51 (64bit). It is broken a "funny" way. When connecting to the FTP server, it asks for credential (TC administrator password), but it gives an empty window (even the parent directory ".." is not displayed). No error message is displayed. Repeated reloading of the directory and connection list the content of the directory. The bug is not regular, is occasional.

Below I could catch logs two connections one after the other in tcftp.log. The first one showed the empty window. The second connection loaded the complete content of the directory. What can be the cause of a half-way "broken" connection? The FTP server support on the other side is clueless.

Code: Select all

1:----------
1:Connect to: (26.08.2020 14:32:59)
1:hostname=svjsvetova523-1.cz
1:username=removed
1:startdir=/svjsvetova523-1.cz/templates/protostar
1:svjsvetova523-1.cz=130.193.9.44
1:220 ::ffff:130.193.9.44 FTP server ready
1:USER removed
1:331 Password required for removed
1:PASS ***********
1:230 Uzivatel removed byl uspesne prihlasen. [translation: The user has been logged in successfully]
1:SYST
1:215 UNIX Type: L8
1:FEAT
1:211-Features:
1: MDTM
1: SSCN
1: TVFS
1: MFMT
1: SIZE
1: PROT
1: CCC
1: PBSZ
1: AUTH TLS
1: MFF modify;UNIX.group;UNIX.mode;
1: REST STREAM
1: MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.mode*;UNIX.owner*;
1: UTF8
1: EPRT
1: EPSV
1: LANG zh-CN;zh-TW;bg-BG;en-US;es-ES;fr-FR;it-IT;ja-JP;ko-KR;ru-RU
1:211 End
1:OPTS UTF8 ON
1:200 UTF8 set to on
1:Connect ok!
1:CWD /svjsvetova523-1.cz/templates/protostar
1:250 CWD command successful
1:PWD
1:257 "/svjsvetova523-1.cz/templates/protostar" is the current directory
1:Get directory
1:TYPE A
1:200 Type set to A
1:PASV
1:OFFLINE6, error=0
1:----------
1:Connect to: (26.08.2020 14:33:06)
1:hostname=svjsvetova523-1.cz
1:username=removed
1:startdir=/svjsvetova523-1.cz/templates/protostar
1:svjsvetova523-1.cz=130.193.9.44
1:220 ::ffff:130.193.9.44 FTP server ready
1:USER removed
1:331 Password required for removed
1:PASS ***********
1:230 Uzivatel removed byl uspesne prihlasen.  [translation: The user has been logged in successfully]
1:SYST
1:215 UNIX Type: L8
1:FEAT
1:211-Features:
1: MDTM
1: SSCN
1: TVFS
1: MFMT
1: SIZE
1: PROT
1: CCC
1: PBSZ
1: AUTH TLS
1: MFF modify;UNIX.group;UNIX.mode;
1: REST STREAM
1: MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.mode*;UNIX.owner*;
1: UTF8
1: EPRT
1: EPSV
1: LANG zh-CN;zh-TW;bg-BG;en-US;es-ES;fr-FR;it-IT;ja-JP;ko-KR;ru-RU
1:211 End
1:OPTS UTF8 ON
1:200 UTF8 set to on
1:Connect ok!
1:CWD /svjsvetova523-1.cz/templates/protostar
1:250 CWD command successful
1:PWD
1:257 "/svjsvetova523-1.cz/templates/protostar" is the current directory
1:Get directory
1:TYPE A
1:200 Type set to A
1:PASV
1:227 Entering Passive Mode (130,193,9,44,250,91).
1:Connected to PASV port
1:MLSD
1:150 Opening ASCII mode data connection for MLSD
1:Download
1:Waiting for server...
1:226 Transfer complete
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elgonzo
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Re: FTP connection broken, empty window, no content, no parent directory

Post by *elgonzo »

As you can see in your log, when TC attempted to engage passive mode the first time, it couldn't successfully establish the passive connection mode (notice the "OFFLINE" line following "PASV").

Now, i cannot telly you why this happened (*). But have you already tried another FTP client to rule out possible network problems unrelated to TC? (The log itself is not sufficient to determine that the problem is caused by TC itself.)

------
(*) It could be -almost- anything. It could be related to TC's ftp client code. It could be the network hardware/drivers or software related to the network protocol stack in your computer. It could be any network device between your computer and the server (that includes your own network devices as well whatever network infrastructure along the way "behind" your ISP. There is also still a small chance that it could also be the server, even if the support staff have no idea what it could be. Without seeing the logs/configuration of the server, i have no reason to categorically rule out the server as a possible source of the problem)
Windows 7 Pro x64 SP1
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ghisler(Author)
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Re: FTP connection broken, empty window, no content, no parent directory

Post by *ghisler(Author) »

The problem seems to be on the server side. Maybe you need to limit the ports used for passive mode.
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ackuxacky
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Re: FTP connection broken, empty window, no content, no parent directory

Post by *ackuxacky »

Thank you for your kind response, dear Christian,

I'm not sure, what did you mean by "limiting the ports". Is it about limiting the number of the connections to the same port at a single time? Should I try "active" instead of "passive" for the other connections?

I usually connect to that particular FTP by two means:
  • FTP by TC
  • KeePass downloads and uploads the KDBX database via FTP
and yes, very often it is at one time.
ghisler(Author) wrote: 2020-08-31, 14:21 UTC The problem seems to be on the server side. Maybe you need to limit the ports used for passive mode.
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ghisler(Author)
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Re: FTP connection broken, empty window, no content, no parent directory

Post by *ghisler(Author) »

Are you the server administrator?
Which ftp server software do you run? Proftpd? Pureftpd? Anything else?
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ackuxacky
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Joined: 2012-09-28, 06:17 UTC

Re: FTP connection broken, empty window, no content, no parent directory

Post by *ackuxacky »

I'm sorry for not answering earlier. No notification email arrived from the forum. (Now, I set to send emails on all post actions.)

I'm not the server administrator.

I'm not aware of the described issue using TC10. Thank you very much for your work!
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