RE: Openssh 2.3.0p1 weird exec problem, cont.

RE: Openssh 2.3.0p1 weird exec problem, cont.

[John Pollock]

i've been seeing this exact issue too and only recently learned to pipe
output through cat if i want to expect to see it reliably come back.  A
command repeated 30 times will return the correct output about 10 times,
and then a variety of other outputs the other 20 times.

However, i've only seen this issue with non-cygwin apps (like VC++ and
such) which don't seem to understand how to send output reliably when
cooperating with a version of ssh using socket pairs instead of pipes.
The cygwin version of openssh, i believe ,uses socket pairs and not pipes,
which may be the source of the problem.

J



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Re: Openssh 2.3.0p1 weird exec problem, cont.

[Corinna Vinschen]

On Fri, Dec 29, 2000 at 03:59:12PM -0500, John Pollock wrote:
> However, i've only seen this issue with non-cygwin apps (like VC++ and
> such) which don't seem to understand how to send output reliably when
> cooperating with a version of ssh using socket pairs instead of pipes.
> The cygwin version of openssh, i believe ,uses socket pairs and not pipes,
> which may be the source of the problem.

That's an interesting point. socket pairs are prefered over pipes in
OpenSSH. Using pipes is a special option. I'm currently on vacation
and need the time for my move to another town. If somebody is willing
to build OpenSSH using pipes and test that situation again I would
gladly appreciate this.

Using pipes instead of socket pairs is easy: After configuring just
open `defines.h', goto line 378 and remove the comments from this
line containing `#define USE_PIPES 1', then make. If that solves the
problem (and still works in all other situations) I will release
a new Cygwin version of OpenSSH then.

Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
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Re: Openssh 2.3.0p1 weird exec problem, cont.

[bailey9]

On Fri, Dec 29, 2000 at 10:30:05PM +0100, Corinna Vinschen wrote:

That seems to solve the problem for me. Thanks!

 .andy

> On Fri, Dec 29, 2000 at 03:59:12PM -0500, John Pollock wrote:
> > However, i've only seen this issue with non-cygwin apps (like VC++ and
> > such) which don't seem to understand how to send output reliably when
> > cooperating with a version of ssh using socket pairs instead of pipes.
> > The cygwin version of openssh, i believe ,uses socket pairs and not pipes,
> > which may be the source of the problem.
> 
> That's an interesting point. socket pairs are prefered over pipes in
> OpenSSH. Using pipes is a special option. I'm currently on vacation
> and need the time for my move to another town. If somebody is willing
> to build OpenSSH using pipes and test that situation again I would
> gladly appreciate this.
> 
> Using pipes instead of socket pairs is easy: After configuring just
> open `defines.h', goto line 378 and remove the comments from this
> line containing `#define USE_PIPES 1', then make. If that solves the
> problem (and still works in all other situations) I will release
> a new Cygwin version of OpenSSH then.
> 
> Corinna
> 
> -- 
> Corinna Vinschen                  Please, send mails regarding Cygwin to
> Cygwin Developer                                mailto:cygwin@cygwin.com
> Red Hat, Inc.
> 
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Re: Openssh 2.3.0p1 weird exec problem, cont.

[Corinna Vinschen]

On Fri, Dec 29, 2000 at 05:21:07PM -0500, bailey9@akamai.com wrote:
> That seems to solve the problem for me. Thanks!

You _did_ recompile OpenSSH with USE_PIPES and that solves
actually the problem? I'm just asking to be really sure.

Corinna

> > On Fri, Dec 29, 2000 at 03:59:12PM -0500, John Pollock wrote:
> > > However, i've only seen this issue with non-cygwin apps (like VC++ and
> > > such) which don't seem to understand how to send output reliably when
> > > cooperating with a version of ssh using socket pairs instead of pipes.
> > > The cygwin version of openssh, i believe ,uses socket pairs and not pipes,
> > > which may be the source of the problem.
> > 
> > That's an interesting point. socket pairs are prefered over pipes in
> > OpenSSH. Using pipes is a special option. I'm currently on vacation
> > and need the time for my move to another town. If somebody is willing
> > to build OpenSSH using pipes and test that situation again I would
> > gladly appreciate this.
> > 
> > Using pipes instead of socket pairs is easy: After configuring just
> > open `defines.h', goto line 378 and remove the comments from this
> > line containing `#define USE_PIPES 1', then make. If that solves the
> > problem (and still works in all other situations) I will release
> > a new Cygwin version of OpenSSH then.

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Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.

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Re: Openssh 2.3.0p1 weird exec problem, cont.

[bailey9]

On Sat, Dec 30, 2000 at 08:00:44PM +0100, Corinna Vinschen wrote:
> On Fri, Dec 29, 2000 at 05:21:07PM -0500, bailey9@akamai.com wrote:
> > That seems to solve the problem for me. Thanks!
> 
> You _did_ recompile OpenSSH with USE_PIPES and that solves
> actually the problem? I'm just asking to be really sure.
> 
> Corinna
> 

 Yup, compiling with USE_PIPES defined eliminates the problem of sometimes 
not getting output from exec'd commands. I haven't tested interactive mode
extensively but at least superficially everything seems to work ok.

 .andy


> > > On Fri, Dec 29, 2000 at 03:59:12PM -0500, John Pollock wrote:
> > > > However, i've only seen this issue with non-cygwin apps (like VC++ and
> > > > such) which don't seem to understand how to send output reliably when
> > > > cooperating with a version of ssh using socket pairs instead of pipes.
> > > > The cygwin version of openssh, i believe ,uses socket pairs and not pipes,
> > > > which may be the source of the problem.
> > > 
> > > That's an interesting point. socket pairs are prefered over pipes in
> > > OpenSSH. Using pipes is a special option. I'm currently on vacation
> > > and need the time for my move to another town. If somebody is willing
> > > to build OpenSSH using pipes and test that situation again I would
> > > gladly appreciate this.
> > > 
> > > Using pipes instead of socket pairs is easy: After configuring just
> > > open `defines.h', goto line 378 and remove the comments from this
> > > line containing `#define USE_PIPES 1', then make. If that solves the
> > > problem (and still works in all other situations) I will release
> > > a new Cygwin version of OpenSSH then.
> 
> -- 
> Corinna Vinschen                  Please, send mails regarding Cygwin to
> Cygwin Developer                                mailto:cygwin@cygwin.com
> Red Hat, Inc.
> 
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Re: Openssh 2.3.0p1 weird exec problem, cont.

[Ed Eden]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

looks like the problem has to do with...


look at message thread...

      CYGWIN Socket write() problem in 1.1.7 DLL

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=5Rw7
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Re: Openssh 2.3.0p1 weird exec problem, cont.

[Ed Eden]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

the command output problem is due to changes in cygwin1.dll. If you
put in version 1.1.4 for me anyway it will give the output
reliability. I put in version 1.1.7 and get the "missing output"
results.


Will the "pipes" compile take care of the output from nt .exe
commands? If your logged in and do a "net" command, the output
doesn't show. I followed someone's advice and made srvany start a
batch file that calls sshd and | (pipes) the output to cmd.exe and
that works. 

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Re: Openssh 2.3.0p1 weird exec problem, cont.

[R v D]

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Openssh 2.3.0p1 weird exec problem, cont.

[bailey9]

 In an effort to debug the weird problem I was having when exec'ing commands
remotely with OpenSSH 2.3.0p1, I've set up a test machine running Cygwin
1.1.7 and OpenSSH-20001221. I still have the problem where sshd only sends
back the output of the command about 20% of the time. The problem only
occurs when the command exits quickly, like say, uname -a. If I do something
like "sleep 1; uname -a", I always get output. Debug logs actually show
that the server returns 0 bytes when the problem is occuring. The machines
are uniprocessor, p3 500s or better, running Win2k with SP1.

 If possible Corinna, I'd like to give you access to the box- the machine
is running Windows Terminal Server and VNC, and has all the cygwin stuff
installed.

 .andy

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Re: Openssh 2.3.0p1 weird exec problem, cont.

[Corinna Vinschen]

On Fri, Dec 29, 2000 at 03:19:56PM -0500, bailey9@akamai.com wrote:
>  In an effort to debug the weird problem I was having when exec'ing commands
> remotely with OpenSSH 2.3.0p1, I've set up a test machine running Cygwin
> 1.1.7 and OpenSSH-20001221. I still have the problem where sshd only sends
> back the output of the command about 20% of the time. The problem only
> occurs when the command exits quickly, like say, uname -a. If I do something
> like "sleep 1; uname -a", I always get output. Debug logs actually show
> that the server returns 0 bytes when the problem is occuring. The machines
> are uniprocessor, p3 500s or better, running Win2k with SP1.
> 
>  If possible Corinna, I'd like to give you access to the box- the machine
> is running Windows Terminal Server and VNC, and has all the cygwin stuff
> installed.

Sorry but that's way beyond what I can do as voluntary support.
You have the sources, strace and a debugger and you can send
debug output to the list. If it contains something helpful
which allows me to reproduce the effect (which isn't the case
here) I will surely have a look into that.

Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
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