Most applications that leverage /usr/bin/ssh
on compute nodes can be configured to use /usr/bin/rsh.
In the event that your application requires SSH access to
compute nodes, ClusterWare provides this ability through
/etc/beowulf/init.d/81sshd.
To start /usr/sbin/sshd on compute nodes,
enable the 81sshd script and reboot your nodes:
[root@cluster ~] # /sbin/beochkconfig 81sshd on
[root@cluster ~] # bpctl -S all -R |
When each node boots,
81sshd starts
sshd on the node,
and the master's root user will be able to SSH
to a compute node without a password, e.g.:
[root@cluster ~] # ssh n0 ls |
By default,
compute node
sshd daemons do not allow for password-based
authentication -- only key-based authentication is available --
and only the root user's SSH keys have been configured.
If a non-root user needs SSH access to compute nodes,
the user's SSH keys will need to be configured.
For example, create a DSA key using ssh-keygen,
and hit Enter when prompted for a password
if you want password-less authentication:
[user1@cluster ~] $ ssh-keygen -t dsa |
Since the master's
/home directory is mounted
(by default) as
/home on the compute nodes,
just copy the public key to ~/.ssh/authorized_keys:
[user1@cluster ~] $ cp -a ~/.ssh/id_dsa.pub ~/.ssh/authorized_keys |
Now the user can run commands over SSH to any node using shared key
authentication:
[user1@cluster ~] $ ssh n0 date |
If you wish to modify
sshd's settings,
you can edit
/etc/beowulf/conf.d/sshd_config
and then reboot the nodes.
Node-specific
sshd configuration settings can be saved as
/etc/beowulf/conf.d/sshd_config.$NODE.
Client behavior for SSH on the nodes can be adjusted by editing the global
/etc/beowulf/conf.d/ssh_config
or a node-specific /etc/beowulf/conf.d/ssh_config.$NODE.
This SSH client configuration will only be useful when using SSH
from node to node. For example:
[user1@cluster ~] $ ssh n0 ssh n1 ls |
Note that
/etc/beowulf/conf.d/sshd_config and
ssh_config only affect SSH behavior on compute nodes.
The master's SSH configuration will not be affected.