<?php
 //include('../cfg/file_name.php');
 $open_dns = '/etc/resolv.conf';
 shell_exec("sudo chmod 777 ".$open_dns);
 $fp = fopen($open_dns,'w') or die("Unable to open file!");

 if(trim($_POST['dns1'])!=""){
  fwrite($fp, "nameserver ");
  fwrite($fp, $_POST['dns1']."\n");
 }
 if(trim($_POST['dns2'])!=""){
  fwrite($fp, "nameserver ");
  fwrite($fp, $_POST['dns2']."\n");
 }
 if(trim($_POST['dns3'])!=""){
  fwrite($fp, "nameserver ");
  fwrite($fp, $_POST['dns3']."\n");
 }
 
 fclose($fp);
 echo "1";

?>