is used by to access the local host keys and generate the digital
     signature required during host-based authentication.  is disabled
     by  default  and  can  only  be  enabled  in  the  global  client
     configuration file by setting to is not intended to be invoked by
     the user, but from See and for more information about  host-based
     authentication.    Controls  whether  is  enabled.   These  files
     contain the private parts of the host keys used to  generate  the
     digital  signature.   They should be owned by root, readable only
     by root, and not accessible to others.  Since they  are  readable
     only  by  root, must be set-uid root if host-based authentication
     is used.  If these files exist they are assumed to contain public
     certificate  information  corresponding  with  the  private  keys
     above.  first appeared in