Re: NAMD on a virtual grid

From: Axel Kohlmeyer (
Date: Mon Jan 26 2009 - 16:02:30 CST

On Mon, 26 Jan 2009, Robert Brunner wrote:

RB> "The authenticity of host..." is produced by the ssh program, not rsh, so
RB> charmrun is trying to run ssh, not rsh. I think rsh is just being used in
RB> the generic sense of remote shell, not the actual rsh program. Now maybe its
RB> not running the same ssh as the one you run from the command line. You might
RB> try specifying a full path to ssh in the nodelist file.
RB> There must be something different between what charm++ is doing vs. what
RB> your command line is doing. You might try writing a little script to wrap
RB> around ssh, then tell charm++ to use that. Once you do that, you could add
RB> diagnostic code, maybe "ssh -vvv" to get verbose debugging output. Or try
RB> printing out the command line parameters charmrun is using, then try
RB> executing those from the command line.

what you want to try out is to use:

ssh -o "StrictHostKeyChecking no"

you probably also want to delete incompatble entries
from previous experiments from ~/.ssh/known_hosts
or set ssh to try write those to /dev/null for each new
launch of a virtual grid. hopefully, charm++ will not
get too confused about the complaining that ssh does.


RB> Robert
RB> On Jan 26, 2009, at 2:38 PM, Benjamin Bouvier wrote:
RB> >On Mon, 26 Jan 2009 20:50:13 +0100, Robert Brunner <>
RB> >wrote:
RB> > >Those "authenticity" messages are coming from SSH via Charm++. You need
RB> > >to get rid of them by setting up SSH so they don't occur. Depending on
RB> > >your system setup, you can probably do this by just manually running ssh
RB> > >from the host node to every other node and answering the questions, or by
RB> > >editing $HOME/.ssh/known_hosts or $HOME/.ssh/known_hosts2 and adding the
RB> > >proper host name keys to those files.
RB> > >
RB> > >Try to login as user root from the command line and see if you can
RB> > >produce those messages.
RB> >
RB> >Thanks for the suggestion Robert. But logging from the command line (using
RB> >ssh root_at_xx.xx.xx.xx) works great, and does not trigger password prompts or
RB> >security questions...
RB> >Hence my fear that Charm++ might not actually be using ssh, but rsh (cf the
RB> >output messages)...
RB> >
RB> > >

Axel Kohlmeyer
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
If you make something idiot-proof, the universe creates a better idiot.

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