Bug#922307: proftpd-basic aborting transfer

[Kim-Alexander Brodowski]

On Mon, 14 Oct 2019 23:13:09 +0200 Hilmar Preuße <hille42 at web.de> wrote:
 > On 2/14/19 1:55 PM, david at daveserver.info wrote:
 >
 > Hi,
 >
 > I've uploaded 1.3.6a to unstable. It contains a fix:
 >
 > - Bug 4319 - FTP uploads frequently break due to "Interrupted system
 > call" error.
 >
 > Does the new version solve your issue?
 >
 > Hilmar
 >
 > --
 > sigfault
 > #206401 http://counter.li.org

Dear Maintainer,

we have recently received reports of customers having issues when 
uploading many HTML files at once (429 items, totaling 3,1 MiB). We can 
reproduce this issue with FTPES (explicit TLS) on both Ubuntu 19.10 with 
FileZilla 3.39.0 and on Windows 10 using WinSCP. On the client side 
(FileZilla) an aborted file transfer is logged as follows:

   Command:    STOR w00017.htm
   Response:    150 Opening ASCII mode data connection for w00017.htm
   Response:    450 Transfer aborted. Link to file server lost
   Error:    File transfer failed
   Status:    Starting upload of 
/home/kab/Desktop/Vertretungsplan/S-stat/52/w/w00017.htm
   Status:    Retrieving directory listing of 
"/home/kim.brodowski/Vertretungsplan/S-stat/52/w"...
   Status:    File transfer successful, transferred 2.1 KB in 1 second

On the server side in proftpd.log we essentially receive the same error:

   2020-02-05 13:14:18,605 iserv.kim.mein-iserv.de proftpd[10571] 
iserv.kim.mein-iserv.de 
(2003:a:422:3ba0:34c8:a6df:1a03:f976[2003:a:422:3ba0:34c8:a6df:1a03:f976]): 
notice: user kim.brodowski: aborting transfer: Link to file server lost

In tls.log I don't see any lines that appear to be of interest at first 
glance, even with verbose logging enabled.

Disabling TLS results in the file transfer proceeding as expected, but 
of course is unsuitable for transfers over the internet.

We're currently running proftpd-basic and proftpd-mod-pgsql version 
1.3.6-4+deb10u3 (stable/Buster). As you have suggested that a newer 
upstream version might resolve the issue I've also backported both 
packages from Bullseye in version 1.3.6b-3. This does not appear to have 
any effect.

--

Mit freundlichen Grüßen
Kim-Alexander Brodowski

IServ GmbH
Entwicklung
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38106 Braunschweig

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