Emulab FAQ: Using the Testbed: Do my nodes have consoles I can look at?
Yes. Each of the PCs has its own serial console line with which you can interact, either directly from your desktop (see tiptunnel entry), or by hopping through the "users" machine, using our console program located in '/usr/testbed/bin'. To connect over serial line to "pc1" in your experiment, ssh into users.emulab.net, and then type console pc1 at the Unix prompt. You may then interact with the serial console (hit "enter" to elicit output from the target machine).
To exit the console program, type Ctrl-]; its just a telnet session.
In any case, all console output from each node is saved so that you may look at it it later. For each node, the console log is stored as /var/log/tiplogs/pcXXX.run. This run file is created when nodes are first allocated to an experiment, and the Unix permissions of the run files permit only members of the project to view them. When the nodes are deallocated, the run files are cleared, so if you want to save them, you must do so before terminating the experiment.
In addition, you can view the console logs from the web interface, on the Show Experiment page. Of course, you may not interact with the console, but you can at least view the current log.