Buggy FTP server :: Support Forum

buranded
Joined:: 2020-02-29
Posts:: 5

Buggy FTP server

2020-02-29 15:56

We have one buggy FTP-server and no way to fix it.
Periodically its crashes on doenloading file and sent this error:

Another FTP-clients such as FileZilla reconnects quickly and quietly and resuming download,
but WinWSP stops fatal:

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buranded
Joined:: 2020-02-29
Posts:: 5

Solution

2020-03-01 14:34

Because our traffic going through our Debian 8 firewall, i can substitute text within TCP-sessions on the fly.
I just used nfqsed to change 426 error code to 110 "comment".

iptables -A INPUT -p tcp -s %BUGGY_FTP_IP% --sport 21 -j NFQUEUE --queue-num 0
/root/nfqsed/nfqsed -s /"426 Cannot RETR. EAccessViolation"/"110 Cannot RETR. EAccessViolation" > /dev/null 2>&1 &

According to:
1. devhub.io/repos/rgerganov-nfqsed
2. github.com/rgerganov/nfqsed
3. sysadmin.ru/articles/izmenyaem-soderzhimoe-tcp-paketov-na-letu

This is a very hacky unusual solution, but now WinSCP reconnects and resuming download quickly and quietly.

PLEASE ADD TO WINSCP ABILITY TO IGNORE 426 ERROR AND AUTORESUMING DOWNLOAD.

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 36,692
Location:: Prague, Czechia

Re: Buggy FTP server

2020-03-03

Please attach a full session log file showing the problem (using the latest version of WinSCP).

To generate the session log file, enable logging, log in to your server and do the operation and only the operation that causes the error. Submit the log with your post as an attachment. Note that passwords and passphrases not stored in the log. You may want to remove other data you consider sensitive though, such as host names, IP addresses, account names or file names (unless they are relevant to the problem). If you do not want to post the log publicly, you can mark the attachment as private.

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