shells on boss) to use the rpc server without an agent running.
Using the no-passphrase key, these changes allow us to use the server
from ops in a very restricted manner. This change is temporary, until
I have something better in place. In the meantime, admin people change
their auth keys files on *boss* as such:

command="/usr/testbed/sbin/sshxmlrpc_server.py -ro",from="ops.emulab.net" ... rest of emulab generated key ...

Note the -ro argument; very important!