ssh works fine, scp fails

Martin Pitt martin at
Mon Jun 16 04:02:06 EST 2003


Am 2003-06-15 10:09 -0600 schrieb Bob Proulx:
> That fact that this fails is disconcerting.  You say that interactive
> ssh works but as soon as you run a command it fails?

exactly. With the addition that scp works when I switch to my former
ISP and that neither MTU reducing nor MSS clamping helps here.

> I see two changes from interactive in the above.  One is that stdin is
> now a pipe and two is that there is a command.  Try just doing one
> thing at a time and what does it say.
>   ssh mpitt at id
>   echo id | ssh mpitt at

Both commands end with the same error message (connection reset by
peer) and with no other output.

> I am also assuming that you have checked out any problems with a
> possible .bashrc file which could be causing trouble.  If bash can
> detect that it is running from a remote shell ala rsh/ssh then it
> sources the user's .bashrc file.  I would double check your
> environment files.  zsh and others probably do something similar.
> One of the FAQ's is that your environment can't say anything for
> non-interactive sessions.  Your original message leads me to believe
> you know about this.  But just making sure.

Of course I checked that.

I know about C programming in general and know how to use a debugger
as well, so I would be pleased to help digging out details in any way.
I can also use ethereal on by box and tcpdump on our house router, but
in this case I would need some advice what to look for, I do not know
much about ethernet sniffing.

Unfortunately I cannot give you an account on my machine since I'm
behind a NAT firewall (just for completeness: my old ISDN connection
was also routed trough NAT which did not seem to have any visible
impact). If it would be of any help to you to get on my box: it should
be possible to establish an ssh tunnel from a system with a real IP to
my box, isn't it?

I have a question for myself: is it possible that it has something to
do with a bad firewall configuration at my ISP? Do scp and 'ssh ...
command' need any additional or different packets compared to ssh? (in
particular: ICMP packets, large packets, reverse connections, etc.)?
It is very confusing that it works with my old provider, but not with
the new one, and scp2 works perfectly as well.

Thanks and have a nice evening!

Martin Pitt
eMail: martin at

"Zwei Dinge sind unendlich: Das Universum und die menschliche Dummheit.
Aber beim Universum bin ich mir noch nicht ganz sicher".
      -- Albert Einstein

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