Thank John and Barry (Barry Branch of FIU) for the kind replies.

It is tempting to configure MPICH to use ssh in place of rsh.
Perhaps I will write some script to add user to the cluster system
so that the public keys of the user is automatically generated
and added to the authorized_keys files of all other nodes automatically.
Otherwise it may be a pain to help each new user to setup the
connection, isn't it? Is there any better idea?

BTW, I comment out the contents of krb5.(c)sh files so that the
kerberos path will not be inserted into the PATH anymore.
But I really hope that there be a better way out.

Best regards,
Kuo Kan LIANG

P.S. I have a very good friend who works in FIU as assistant prof.
in the chemistry department of FIU now. Do you know anybody
in the chemistry department, Barry?

Quoting John Hearns <[log in to unmask]>:

>> However, since I believe that many will use SL as the OS for clusters,
>> and MPICH will use rsh, so I think it helpful to make a summary here.
>
> You are correct, it is usual for MPICH to use rsh.
>
> For information, MPICH can be configured to use ssh.
> (You can arrange for a temporary key to be generated, or to use
> passwordless keys).
>
>> Therefore, when I tried to do rsh, the krb5 and krb4 versions are 
>> tried first.
>> Is there any good way to modify this setting so that all of the rsh calls
>> goes to /usr/bin/rsh ?
> We have met this problem also. I would just edit or disable  the krb5
> script.
>