Please note that you can use this function to get the value of FTP_USEPASSIVEADDRESS option also :
<?php
$conn = ftp_connect("host");
$login = ftp_login($conn, "user", "password");
var_dump(ftp_get_option($conn, FTP_USEPASVADDRESS)); // true (which is the default value)
ftp_set_option($conn, FTP_USEPASVADDRESS, false); // change the value
var_dump(ftp_get_option($conn, FTP_USEPASVADDRESS)); // false
?>