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Subject: Re: libssh2 takes long time to disconnect from CoreFTP's SFTP service

Re: libssh2 takes long time to disconnect from CoreFTP's SFTP service

From: Peter Stuge <peter_at_stuge.se>
Date: Fri, 19 Feb 2010 09:42:19 +0100

Xu, Qiang (FXSGSC) wrote:
> > It gets stuck just waiting and after a 10 minute delay the
> > server (not libssh2) closes the connection. A timeout is
> > probably configured in the server.
>
> Thank you, Peter! You are right, again! Just found out that there
> is a setting of "idle timeout" in CoreFTP server, and it is 600
> seconds by default. Please look at the attached screenshot.
..
> Anyway, it looks like a server's issue, not the problem of libssh2.
> By the way, libssh2 works perfectly well with OpenSSH and FreeFTPd,
> the other two Windows application that can provide SFTP service.

Hmm.

Maybe this is a problem in libssh2 anyway. The library must be able
to close an SFTP connection without depending on a timeout or
configuration setting on the server side. Imagine what would happen
if the server is using an infinite timeout!

Of course - it is possible that the server is not behaving correctly,
but I would like it to be investigated further to be certain.

The question is if libssh2 is correct when it starts to wait, or if
it should actually continue to close the connection.

> > It would be good to have this in the bug tracker so that it
> > is not lost. Could you create a ticket for it? The component
> > should probably be "protocol" even though the problem is only
> > seen with SFTP so far.
>
> Since it is due to the server's setting, I am not sure whether I
> shall continue to create a ticket for it.

Please do, it is good also for documenting that we know about this
problem, even if it is not the fault of libssh2.

> > > Another word: FileZilla is using PSFTP.exe to do SFTP transactions,
> > > and it is fast. Hope this helps.
> >
> > Yes that's right! There is no doubt that this is a problem in libssh2.
>
> Just want to clarify that with the 600 sec idle timeout at the server's
> end, FileZilla connects fast, but the same delay appears when I tried
> to do anything further.

Oh! That is interesting.

> Sorry that I didn't do thorough testing on FileZilla.

Hm. Is there any SFTP client (in Windows there is also WinSCP, and
maybe you or a co-worker can test Cyberduck on Mac OS X?) working
correctly with this server?

> Thanks a lot for the help provided, Peter!

Thanks for the report. I think it's a serious problem.

//Peter
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Received on 2010-02-19

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