phpseclib：如何给出IF条件来检查建立的连接与否

I have PHP script which uses ssh utility to connect to a remote Ubuntu machine for executing some commands there. The script is as given below.

<?php
    include('Net/SSH2.php');

    define('NET_SSH2_LOGGING', NET_SSH2_LOG_COMPLEX);

    $ssh = new Net_SSH2('10.3.2.0');
    if (!$ssh->login('makesubdomain','abcdabcd')) {
        exit('Login Failed');
    }
    echo $ssh->exec('/usr/local/listdomain.backup/test/makedir.sh');
?>

Here my problem is, how can I give an if condition to check whether the connection failed or not. I am trying to modify the above code something like this, but I know this is very wrong.

<?php
    include('Net/SSH2.php');

    define('NET_SSH2_LOGGING', NET_SSH2_LOG_COMPLEX);

    if(!$ssh = new Net_SSH2('10.3.2.0')) // Here how can I give condtion
    {
        echo "Connection failed";
    }else{
         if (!$ssh->login('abcd','abcdabcd')) {
             exit('Login Failed');
         }
         echo $ssh->exec('./test.sh');
    }
?>

Please help me as I am very beginner in php. Thanks

The answer you're looking for is:

It's already all there in the example you've given, no need to modify the code.

$ssh->login() does exactly what you want: It tries to connect AND login to the server you've given it, and it will return false in case that failed.