Here is my dilemma:

I want to shutdown a number of computers in my lab. Hostnames are jmud1, jmud2, jmud3 and jmud4 .... jmud20.

Current script or command used:

#!/bin/csh

foreach num (`/root/tools/machines`)
rsh jmud{num} /sbin/shutdown -hy 0 &

end

#End of Script

The file "machines" have the numbers of my hosts 1 - 20.

How do I replace is with ssh or something useable in RHEL5?

Change the "rsh" to "ssh" in the script on the source host.
On the source host you have to generate a key with ssh-keygen (e.g. ssh-keygen -t dsa) as the user that will run the script. Typically this will put the public and private keys in user's $HOME/.ssh directory.

On all the target hosts (jmud1, jmud2 etc...):
1) Remove all the user .rhosts files to prevent rsh from working. (Not required to get ssh working but a damn good idea from a security standpoint.)
2) Setup ssh trust from the server where you're running the script to this target by creating $HOME/.ssh for the user on the target host and create an authorized_keys file in there. Put the contents of the public key from the source host in this.

After that do an ssh to each of the targets from the source so it will prompt you to store known hosts' keys on the source and not ask during the script run.

Note:
$HOME must be writable only by the user but can be accessible by all. $HOME/.ssh must be read/write only by the user and no one else. If this isn't the case then you will still be prompted for password which defeats the point in establishing the trusts.

1 members found this post helpful.

I will try it.

Thank You!