Auto Create Random Subdo

<html>
<style type="text/css">
html {
    text-align: center;
}
a {
    text-decoration: none;
    color: black;
}
</style>
<h1>Auto Generate Random Subdomains</h1><br>
<h4>Coded By : Bayz21</h4><br>
<form method="post">
Target: <br>
<input type="text" name="dom" size="50" height="10" placeholder="sontolo.com" style="margin: 5px auto; padding-left: 5px;"><br>
Nama File : <br>
<input type="text" name="file" size="50" height="10" placeholder="Nama File" style="margin: 5px auto; padding-left: 5px;"><br>
<input type="submit" name="x" style="width: 150px; height: 25px; margin: 5px;" value="hajar">
</form>
</html>


<?php
if($_POST['x']){
$file = $_POST['file'];
$dom = $_POST['dom'];
for ($n=0; $n<999999; $n++) {
    $randomNum=substr(str_shuffle("0123456789abcdefghijklmnopqrstvwxyz"), 0, 24);
$mbut = "http://" . $randomNum. "." .$dom . "
";
  $fh = fopen("$file", "a");
        fwrite($fh, $mbut, strlen($mbut));

}
}

?>