sub establishSession {
   my  @sshPort;
  if ($sshPort =~ /(\d+)/)
    {@sshPort = ("port", $1)}
else {return &error ("invalid port number");}
 
  &xferOpen ('SESSION', $clusterHost,"compression", "yes", @sshPort)
 
||  return &error("couldn't connect to $clusterHost : $xferError");

  return $success;
}