Are remote pipes fixed in 3.5?

From: James Dennis (jdennis@law.harvard.edu)
Date: 01/23/03

  • Next message: James Dennis: "Re: Question" 
    Date: Thu, 23 Jan 2003 11:17:41 -0500
From: James Dennis <jdennis@law.harvard.edu>
To: kamath@geekoids.com, secureshell@securityfocus.com

    I believe I responded a little too quickly without understanding
    everything completely. My apologies. 

    -- 
James Dennis
Harvard Law School
"Not everything that counts can be counted,
and not everything that can be counted counts."
Sean Kamath wrote:
> Trolling through the mailing list archives, I've found both on the
> developer list as well as this list questions about remote pipes
> causing problems with SSH2 (but not SSH1) connections.  The problem
> I'm talking about is this:
> 
> ssh -2 remotehost yes | dd of=/dev/null count=2
> 
> This will hang.  the 'yes' program running on remotehost will block,
> and ssh will never return.  dd will have exited.  Using -1 will work
> fine.  Basically, SSH2 will shut down the channel without telling the
> remote side that stdout has closed.  Note that you can play all sorts
> of games with -n and -f, but nothing fixes it (if you use -f, the dd
> will exit and it will "appear" to work, but actually all that happens
> is the ssh is running in the background, and the remote 'yes' is still
> running (though blocked)).
> 
> ssh -v -v -v output:
> 
> ...
> debug1: Sending command: yes
> debug1: channel request 0: exec
> debug2: callback done
> debug1: channel 0: open confirm rwindow 0 rmax 16384
> debug2: channel 0: rcvd adjust 32768
> debug1: channel 0: write failed
> debug1: channel 0: close_write
> debug1: channel 0: output open -> closed
> debug1: channel_free: channel 0: client-session, nchannels 1
> debug3: channel_free: status: The following connections are open:
>   #0 client-session (t4 r0 i0/0 o3/0 fd 5/-1)
> <I Hit ^C Here>
> debug3: channel_close_fds: channel 0: r 5 w -1 e 7
> 
> 
> Nicholas William's post on the developer list in December of 2001 said
> something about a patch needing to be applied to nchan.c in
> chan_failed_write2().  So, is this fixed in 3.5?  I think the
> developers agree that shutting down the connection is the right thing
> to do (it's what rsh does), so I just need to know if it's in 3.5 to
> make it worth upgrading from Solaris 9's ssh.
> 
> What I'm trying to do is the ubiquitous backup-over-ssh, and end of
> tape detection is driving me nuts.  Something as simple as:
> 
> ssh host ufsdump / | dd od=/dev/rmt/0
> 
> WILL NEVER END when the tape runs out.  Sigh.
> 
> Sean
> 
> PS If this is not fixed, I'll post to the developer list. . .
>

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