[clug] Odd ssh/scp problem

David Price david.price at anu.edu.au
Wed Mar 10 04:56:29 GMT 2004

On Wed, Mar 10, 2004 at 02:14:44PM +1100, Martijn van Oosterhout wrote:
> This should clarify this for you:
> http://sites.inka.de/sites/bigred/devel/tcp-tcp.html

> On Wed, Mar 10, 2004 at 01:52:15PM +1100, Antti.Roppola at brs.gov.au wrote:
> > Dear all,
> > 
> > Last night I was building a Sparc 5 while watching TV:
> > 
> >  - ssh into the Sparc from a laptop
> >  - download kernel source onto laptop
> >  - scp kernel source back from the laptop via the ssh session
> > 
> > However, every time I do this, the laptop's NIC locks up, usually after
> > transferring a few Mb or so. I then need ti ifup/ifdown the laptop's NIC.
> > 
> > I ended up FTPing via another box, but am curious as to what is going on.
> > Presumably layering ssh does curious things.

It doesn't sound to me like there is any IP over TCP happening.
Assuming you are just SSHed into another machine, and you scp back to
the one you are actually on, that happens as a separate connection.
Unless you are using ssh's port tunnelling?  Even then, I think it
would probably be okay, since as far as I know, there is only going to
be one TCP stack.

Also, a problem caused by TCP over TCP probably shouldn't be causing
the link to completely lock up.  Can you still ping the laptop?

I'd be looking for some sort of driver/hardware problem.  IRQ problems
etc.  Can you make it lock-up by any other means?  eg, combination of
heavy network traffic, disk use, CPU use, and keyboard/mouse use.  Are
there any kernel messages when it locks up?


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