Re: Hangs when downloading large files

[Greg Ferrar <ferrar@xxxxxxxxxxxxxx>]

Andreas,

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:

 ssh_options_set(sshSession, SSH_OPTIONS_LOG_VERBOSITY_STR, 
"SSH_LOG_FUNCTIONS");

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?

-
Greg




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