#-- set up a new connection
$ssh = Net::SSH::Perl->new("$host", debug => 1, use_pty => 1, interactive => 1,  identity_files => [], protocol=>'2,1');
#-- authenticate
#print "Loggin onto $host...\n" ;
#  Authenticate using login/password:
$ssh->login($user, "$pass");
my($stdout1, $stderr1, $exit1) = $ssh->cmd("su -", ["$mypassword\r\n"]);
print "error= $stderr1\n" ;