Disable_node_to_node_root_passwordless_access

1. Limiting ssh passwordless access on nodes

In xCAT 2.6 or later, a new attribute sshbetweennodes is defined for site table. This attributes defaults to ALLGROUPS, which means we setup ssh between all nodes during the install or when you run xdsh -K, or updatenode -k as in the past. This attribute can be used to define a comma-separated list of groups and only the nodes in those groups will be setup with ssh between the nodes. The attribute can be set to NOGROUPS, to indicate no nodes (groups) will be setup. Service Nodes will always be setup with ssh between service nodes and all nodes. It is unaffected by this attribute. This also only affects root userid setup and does not affect the setup of devices.

This setting of site.sshbetweennodes will only enable root ssh between nodes of the compute1 and compute 2 groups and all service nodes.

"sshbetweennodes","compute1,compute2",,