process_login.php: Process the login.

<?
$host = "localhost";// the host that u are connecting
$username = "root";// user name
$password = ""; // passworld
$basedatos = "forum"; //Dont change this1.
$db = mysql_connect($host, $username, $password);
mysql_select_db($basedatos, $db);
$user= $_REQUEST['username'];
$pass= md5($_REQUEST['password']);
$query1= "SELECT * FROM smf_members WHERE memberName='$user'";
$mkquery= mysql_query($query1,$db);
$row1= mysql_fetch_assoc($mkquery);
if ($row1['memberName'] == $user) {
if ($row1['passwd'] == $pass) {
/* I seted them to 1 hour duration of login. If you want you can change it. */
setcookie("altuser",$user,time()+3600);
setcookie("altpass",$pass,time()+3600);
?>
<script language="javascript">
alert("Login correct, redirecting to main page.")
location.href= "URL OF MAIN PAGE";
</script>
<?
}
else {
echo "The password is incorrect.";
}
}
else {
echo "The user doesnt exist.";
}

compare_us.php: This page MUST be included in the pages that u want to check access...

<?
$host = "localhost";// the host that u are connecting
$username = "root";// user name
$password = ""; // passworld
$basedatos = "forum"; //Dont change this1.
$db = mysql_connect($host, $username, $password);
require_once("dbconnect.php");
mysql_select_db($basedatos, $db);
if(isset($HTTP_COOKIE_VARS['altuser']) && isset($HTTP_COOKIE_VARS['altpass'])) {
$user= $HTTP_COOKIE_VARS['altuser'];
$pass= $HTTP_COOKIE_VARS['altpass'];
$query1= "SELECT * FROM smf_members WHERE memberName='$user'";
$mkquery= mysql_query($query1,$db);
$row1= mysql_fetch_assoc($mkquery);
if ($row1['memberName'] == $user) {
if ($row1['passwd'] == $pass){
$loginok= true;
}
else {
$loginok= false;
echo "The password is bad. Login again please.";
}
}
else {
$loginok= false;
echo "Something is wrong... The user doesnt exist?...";
}
}
?>

Finally... This finishes... To see if the user is loged in you only need to do:
<?
require_once("compare_us.php");
if ($loginok == true) {
?>
HTML HERE
<?
}
else {
echo "You must login to do that...";
}
?>

or die (mysql_error(););

...

$userexist = @mysql_num_rows($query)
if ($userexist == 1)
{
$query = @mysql_query("SELECT passwd FROM `smf_members` WHERE memberName='$user'")or die('Could not complete query: ' . mysql_error());
$passcheck = @mysql_num_rows($query)
if ($passcheck > 0)
{

...

if( $mkquery && @mysql_num_rows($mkquery) > 0 )