sub establishSession {
   my  @sshPort;
  if ($sshPort =~ /(\d+)/)
    {@sshPort = ("port", $1)}
else {return &error ("invalid port number");}

for (my $tries = 1; $tries < 4; $tries++) { 

print "Attempt $tries to connect\n";
  
&xferOpen ('SESSION', $clusterHost,"compression", "yes", @sshPort);
} 

return &error("couldn't connect to $clusterHost : $xferError");

  return $success;
}