The Rhosts authentication component
  (pam_sm_authenticate()), returns success if and only
  if the target user's UID is not 0 and the remote host and user are listed in
  /etc/hosts.equiv or in the target user's
  ~/.rhosts.
The following options may be passed to the authentication
  module:
  - debug
- syslog(3) debugging
      information at LOG_DEBUGlevel.
- no_warn
- suppress warning messages to the user. These messages include reasons why
      the user's authentication attempt was declined.
- allow_root
- do not automatically fail if the target user's UID is 0.