For the record...
I have gotten around my difficulty thanks to the option "ProxyCommand"
in ssh. I now have the following lines in my ~/.ssh/ssh_config
Host remote_for_sage
ProxyCommand ssh gateway nc -w 1 remote 22
and that (along with all the passwordless authentication associated)
does the trick.
It essentially tells my ssh to create a new virtual host called
"remote_for_sage", so that
- "ssh remote_for_sage" will actually return a SSH connection to
"remote", but through the machine "gateway"
- "ssh -t remote_for_sage magma" will similarly run magma on
"remote" through "gateway"
- "ssh remote" is not affected at all (and in my case won't work,
as "remote" is shielded by "gateway", that was the point)
- "scp remote_for_sage" will *also* be tunneled through
"gateway" (that's the power of ProxyCommand)
So when I do
sage: magma = Magma(server = "remote_for_sage")
, that ssh_config takes care of everything and the fact that it is
tunneled through gateway is entirely transparent to sage.
Paul
On Aug 16, 9:26 am, "[EMAIL PROTECTED]"
<[EMAIL PROTECTED]> wrote:
> I will try, don't hold your breath.
> Even without my additional problem of having to go through a gate, it
> looks as if the scp file tranfers have only been implemented for
> copies of sage (sage0.py, which is the only place scp appears), not
> for a general expect interface (see line
> eval_using_file_cutoff = 0 # don't allow this!
> in expect.py)
> In some sense that's enough in most cases (you can have a situation
> where exact-same-version SAGE's do all the communicating, and each
> runs different CAS on different machines), but there would be another
> extra overhead and one can not always install sage on remote.
> Paul
>
> On Aug 16, 3:20 am, "William Stein" <[EMAIL PROTECTED]> wrote:
>
> > On 8/15/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> > > good catch, you can debug remotely on my computer :)
> > > yes, william, you are right: the small examples work but not the big
> > > ones. i didn t anticipate that SAGE was using files behind the scenes
> > > (i don't know anything about how that works).
> > > in any case, the fact that sage uses scp is not really a problem. this
> > > is another workaround:
> > > ssh -t tunnel scp test_file remote:~/test_file
> > > (after setting all the passwordless stuff)
> > > so if that s all that s needed, maybe one could add to the server
> > > option of the interface a prefix and a suffix to trail the scp command
> > > with, and the same for the ssh (or rsh or whatever is used)
>
> > You could try implementing this. Take a look at
> > SAGE_ROOT/devel/sage/sage/interfaces/expect.py
> > and
> > SAGE_ROOT/devel/sage/sage/interfaces/mathematica.py
> > Do a text search for "scp" in there. Make changes and do
> > "sage -br" to start SAGE with the changes in effect.
>
> > William
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