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Re: Hangs when downloading large files


Are you saying that LogLevel DEBUG2 doesn't provide the debugging you need? Because I still can't get the other way to work. Here's the line:

 Subsystem       sftp    /usr/libexec/openssh/sftp-server -l DEBUG2

and here's what sshd has to say about it:

[root@wisteria ~]# /usr/sbin/sshd -p 1234
/etc/ssh/sshd_config line 120: garbage at end of line; "-l".

Changing the line back to what it used to be:

 Subsystem       sftp    /usr/libexec/openssh/sftp-server -l DEBUG2

fixes the error, and lets me start the port 1234 server without problems--that's how I generated the sshd debugging output I attached in my previous message.

There is nothing about debugging in my "man sftp-server". I suspect we have different versions of sshd, and mine doesn't support this "-l DEBUG2" switch on sftp-server. Do you need me to track this issue with -l down, or did the LogLevel debugging I sent earlier give you what you needed?

I already enabled libssh debugging, though in a slightly different (but I believe equivalent) way:


That debugging output is in the file I attached earlier--I think it's called sawmill_libssh.log or something like that.

Do you need anything further from me to diagnose the problem?


Andreas Schneider wrote:
On Tuesday 09 March 2010 18:05:21 you wrote:

It didn't work to add "-l DEBUG2" to Subsystem--it complained about
"garbage (-l)" at the end of the line. My path is slightly different,

  Subsystem       sftp    /usr/libexec/openssh/sftp-server

so maybe this has to do with the version. I tried adding "LogLevel
DEBUG2" to the file, though, and it seems to have worked--at least, I
get what looks like level-2 debugging from the server. I've attached the
server's debug output, and Sawmill+libssh debug output.

If you set it the variable in the config file you enable debug logging of sshd.

Take a look in 'man sftp_server'. I've set

Subsystem       sftp    /usr/lib64/ssh/sftp-server -l DEBUG2

and restarted sshd. I got a lot of debugging output from the sftp server.

To enable logging in libssh you have to set:

int verbosity = SSH_LOG_FUNCTIONS;
ssh_set_options(session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
If this is a server bug, I will be content to just document it,
especially if there's a newer version of the server which fixes it. Do
you know if there is?

That's what we should confirm. It is possible that it is a bug in libssh.
I don't understand the sshfs code enough to know what we would have to
do similarly. Is this a change that would be made in libssh, or is this
a change I could make in my client program? I suspect the former; it
seems to have to do with throttling the amount of outstanding data
somehow, and I don't think the libssh API provides any functionality for
determining what's outstanding. Is there some way I can implement this
on my end?

Lets look at the logs and then we can try to create a testcase for it.

	-- andreas

Re: Hangs when downloading large filesAndreas Schneider <mail@xxxxxxxxxxxx>
Re: Hangs when downloading large filesAndreas Schneider <mail@xxxxxxxxxxxx>
Re: Hangs when downloading large filesGreg Ferrar <ferrar@xxxxxxxxxxxxxx>
Re: Hangs when downloading large filesAndreas Schneider <mail@xxxxxxxxxxxx>
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