[nzlug] ProFTPd 1.2.10 - terminating (signal 11) - Randomly.

[Greg Fawcett]

I assume you've googled... from a cursory look, it sounds like it is a
segfault, which could be caused by anything. I'm guessing it will turn out
to be a bug, triggered only by something unique to the particular customer.

To narrow it down, I'd want to run the proftpd on another server, with the
same auth and user setup, to see if the bug follows. If it does, it also
gives you the opportunity to test on a non-production system. You could then
attach to the appropriate processes with gdb, and when it segfaults, use bt
to show exactly where it happened (you'd possibly need to recompile with
debug symbols included).

This may give you an understanding of how you can work around the problem,
and also plenty of fodder to send to the maintainers to fix the bug.

Good luck.

Greg.

2008/7/31 Michael Hutchinson <mhutchinson at manux.co.nz>

> Hello everyone,
>
>
>
> We're currently having a problem on a major web server, with ProFTPd.
> For a specific Client we host, 3 directories are a problem over an FTP
> connection. Most of the time, when reading the directories in question,
> the Server stops (with signal 11) and leaves the FTP client
> disconnected. This only kills the child process on the server - and the
> FTP client can reconnect again straight away. Retries on the FTP client
> do produce a directory listing that works, but a simple refresh of the
> directory can cause the FTP client to be disconnected again straight
> away.
>
>
>
> I had originally thought that this was a file naming convention problem,
> but have disproved this by using another bunch of files in the
> directories that have issues, and can reproduce the error using any
> files.
>
> I would then have expected a permissions problem with the directories
> that fail listing - but no, they are exactly the same as every other
> client we do hosting for - and none of them have this problem - besides
> that, it wouldn't explain the randomness of the event. If there was a
> permission problem, it would be a permanent one, not a random
> experience.
>
>
>
> I have tried Stack Tracing the ProFTPd main process and the child
> process when one has logged in, but to no avail. Apart from failing
> Reverse DNS lookups on occasion, that's all I see in the stack traces.
> (I have since fixed the rDNS issue anyway and that hasn't helped).
>
>
>
> I have noticed this error in the ProFTPd log file :
>
> PAM(tile): User not known to the underlying authentication module.
>
> Though this appears for every Client we host when logging in via FTP,
> and never seems to cause a problem.
>
>
>
> I am unable to replicate the connection drop issue on other Client's
> sites that we host. We've been hosting websites on this server for
> years, and haven't come across a problem like this in that time. We're
> running Debian Sarge (I know it is old) - but this helps the point that
> not much has changed recently.
>
>
>
> Does anyone have some ideas as to what the problem might be?
>
> Thanks in advance,
>
>
>
> Michael Hutchinson
>
> Manux Solutions Ltd
>
> | Phone: 0800 328 324
>
> | Email: mhutchinson at manux.co.nz
>
> | Web:   http://www.manux.co.nz/
>
>
>
> _______________________________________________
> NZLUG mailing list NZLUG at linux.net.nz
> http://www.linux.net.nz/cgi-bin/mailman/listinfo/nzlug
>



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