yet another mpich error

[Nikola Skoric]

I configured mpich with -rsh=ssh. Then I tried to execute an example,
and here's what heppened:

***@rilmir:~/Desktop/mpich/mpich-1.2.7p1/examples/basic$ mpirun -np 4
cpi
ssh: connect to host rilmir port 22: Connection refused

I searched documentation, I googled about this error, I just can't
find no answers. Anybody has an idea?

[Ron Croonenberg]

Well, you need to have sshd running on all nodes.
Than also you have to move some keys/certificates around and set ssh up
so that it allows you passwordless logins from all nodes to all nodes.

I just use rsh, because all slaves are on a private network behind the
head node and can't be reached. The head node is connected to the public
net but has a firewall running for the public interface.
I think it is easier to maintain too, in case a node needs to be
replaced or when nodes are added.

Ron

Post by Nikola Skoric
I configured mpich with -rsh=ssh. Then I tried to execute an example,
cpi
ssh: connect to host rilmir port 22: Connection refused
I searched documentation, I googled about this error, I just can't
find no answers. Anybody has an idea?

[Nikola Skoric]

Dana Sun, 28 Oct 2007 12:39:31 -0400,

Post by Ron Croonenberg
Well, you need to have sshd running on all nodes.
Than also you have to move some keys/certificates around and set ssh up
so that it allows you passwordless logins from all nodes to all nodes.
I just use rsh, because all slaves are on a private network behind the
head node and can't be reached. The head node is connected to the public
net but has a firewall running for the public interface.
I think it is easier to maintain too, in case a node needs to be
replaced or when nodes are added.

Huh, I forgot to mention: I'm testing this on just one computer. I'll
be running this code on a cluster, but for now I need to parallelise
it first.

The other problem is I don't know nothing about sshd
administration. Now, I'm sure I could figure it out in one day, but if
I can do this without self-educating myself in sshd and public key
cryptography, that would be really nice since I don't have much
time. So, is there a way to do this on just one host without messing
with ssh certificates?

[Ron Croonenberg]

Yes you can run multiple processes on one node.

You still have to "mess" with ssh or something else (rsh).
In case of passwordless ssh, I assume you don't want the whole world
login passwordless into your machine so you have to do something.

Post by Nikola Skoric
Dana Sun, 28 Oct 2007 12:39:31 -0400,

Post by Ron Croonenberg
Well, you need to have sshd running on all nodes.
Than also you have to move some keys/certificates around and set ssh up
so that it allows you passwordless logins from all nodes to all nodes.
I just use rsh, because all slaves are on a private network behind the
head node and can't be reached. The head node is connected to the public
net but has a firewall running for the public interface.
I think it is easier to maintain too, in case a node needs to be
replaced or when nodes are added.

Huh, I forgot to mention: I'm testing this on just one computer. I'll
be running this code on a cluster, but for now I need to parallelise
it first.
The other problem is I don't know nothing about sshd
administration. Now, I'm sure I could figure it out in one day, but if
I can do this without self-educating myself in sshd and public key
cryptography, that would be really nice since I don't have much
time. So, is there a way to do this on just one host without messing
with ssh certificates?

[Nikola Skoric]

Dana Sun, 28 Oct 2007 12:39:31 -0400,

Post by Ron Croonenberg
I just use rsh

Hm, I reread your post and figured out I missed this part and then
tried to use rsh. What I discovered is this:
***@rilmir:~$ type rsh
rsh is /usr/bin/rsh
***@rilmir:~$ rsh
usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]
[-D [bind_address:]port] [-e escape_char] [-F configfile]
[-i identity_file] [-L [bind_address:]port:host:hostport]
[-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
[-R [bind_address:]port:host:hostport] [-S ctl_path]
[-w tunnel:tunnel] [user@]hostname [command]

So, rsh is not aliased to ssh, but it represents itself as ssh. It
seems I just can't use rsh explicitly...

[Nikola Skoric]

Dana Sun, 28 Oct 2007 18:42:51 +0000 (UTC),

Post by Nikola Skoric
So, rsh is not aliased to ssh, but it represents itself as ssh. It
seems I just can't use rsh explicitly...

I installed rsh-client. Now I can use rsh. And now I figured out that
I need rshd too (forgot to turn my brain on). So, is it easier to
configure rshd or sshd?

[Ron Croonenberg]

I think it is. don't get me wrong, ssh can be set up correctly too.
I just find it easier to keep things going after I swap nodes or add
nodes with rsh than with ssh

yes you need to install the rsh server package of course.
Than create rhosts files and you're in business.

Post by Nikola Skoric
Dana Sun, 28 Oct 2007 18:42:51 +0000 (UTC),

Post by Nikola Skoric
So, rsh is not aliased to ssh, but it represents itself as ssh. It
seems I just can't use rsh explicitly...

I installed rsh-client. Now I can use rsh. And now I figured out that
I need rshd too (forgot to turn my brain on). So, is it easier to
configure rshd or sshd?

[Ron Croonenberg]

I don't know what you are using, but if it is mpich-2, you need to
reconfigure/recompile/install it with the rsh options.
(Of course rsh needs to be on your box, the server also... and of
course it needs to be configured too (rhost files etc)

Post by Nikola Skoric
Dana Sun, 28 Oct 2007 12:39:31 -0400,

Post by Ron Croonenberg
I just use rsh

Hm, I reread your post and figured out I missed this part and then
rsh is /usr/bin/rsh
usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]
[-D [bind_address:]port] [-e escape_char] [-F configfile]
[-i identity_file] [-L [bind_address:]port:host:hostport]
[-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
[-R [bind_address:]port:host:hostport] [-S ctl_path]
So, rsh is not aliased to ssh, but it represents itself as ssh. It
seems I just can't use rsh explicitly...

[Nikola Skoric]

Dana Sun, 28 Oct 2007 16:10:28 -0400,

Post by Ron Croonenberg
I don't know what you are using, but if it is mpich-2, you need to
reconfigure/recompile/install it with the rsh options.
(Of course rsh needs to be on your box, the server also... and of
course it needs to be configured too (rhost files etc)

There we go again. I have mpich 1.2.7 and I don't have rsh server
running. So I have to learn to configure rsh. Well, then I'll just
learn how to configure passwordless ssh, why bothering with rsh :-)
That is, if I catch time to learn how to configure passwordless ssh.