TODO

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  Note that root won't be able to change anyone's passwords via this
method, as RADIUS doesn't support the notion of root.

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  Add in pam_set_data && pam_get_data to keep track of which RADIUS
  server we were talking to, and what the session_time was.

  Oddly enough, the session_time information seems to be happy to be
  a 'static', but the radius_server_t *live_server doesn't.  It works
  for login, is re-used for open_session, but is ignored for close_session.

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