<?php
$host = 'example.com';
$password = 'pass';
$username = 'username';

try {
 $result = checkFtp($host, $username, $password);
} catch(Exception $e) {
 $result = $e->getMessage();
}

if($result) {
   print 'ok';
} else {
   print 'fail';
}

function checkFtp($host, $username, $password, $port = 21, $timeout = 10) {
        $con = ftp_connect($host, $port, $timeout);
        if (false === $con) {
            throw new Exception('Unable to connect to FTP Server.');
        }
        $loggedIn = ftp_login($con,  $username,  $password);
        ftp_close($con);
        if (true === $loggedIn) {
            return true;
        } else {
            throw new Exception('Unable to log in.');
        }
}