fair play i just started so u prob do this
$_GET['user'] = abs((int) $_GET['user']);
$check=$db->query("select userid, lastip_login FROM users where userid ='.$_GET['user'].'");
$r=$db->fetch_row($check);
if($ir['lastip_login'] == $r['lastip_login'])
{
echo "No same ip transfers allowed";
}