Kbrootpw
Emulab FAQ: Security Issues: Do nodes have root passwords?
Yes, your nodes do have a root password and you can log in on the console or via ssh if you know it. For obvious security reasons, it would not be a good idea for all nodes in the cluster to have the same password, so on each experiment swapin, all of the nodes in your experiment get a new randomly generated root password. This root password is different on each of your nodes, and different from all other nodes in the cluster.
To see the root password for a node, click on the node in the list shown on the Show Experiment page for your experiment. Near the bottom is an attribute labeled root_password.