PHP code for detecting vuln scans

<?php
function startsWith($haystack, $needle)
{
    $length = strlen($needle);
    return (substr($haystack, 0, $length) === $needle);
}
function startsWithBlocked($needle)
{
    $blockStarts = array(
        "wp-", "w00tw00t", "server-status", "cgi", "home", "docs", "xmlrpc", "admincp.php", "install.",
        "web.conf", "_vti_i", "version", "pass", "~", "php-bin", "thumbs", "appConf.htm", "user",
        "pma", "myadmin", "admin", "phpmyadmin", "php-my-admin", "webcalendar", "calendar", "dbadmin",
        "mysql", "include", "public_calendar", "web-calendar", "webcalendar", "wcalendar"
    );
    foreach($blockStarts as $i => $value)
    {
        if(startsWith($needle, $value))
        {
            return true;
        }
    }
    return false;
}
function Sanitize($uri)
{
    $uri = strtolower($uri);
    $uri = urldecode($uri);
    while(startsWith($uri, "/") || startsWith($uri, "./"))
    {
        $length = strlen($uri);
        if(startsWith($uri, "/"))   $uri = substr($uri, 1, $length - 1);
        else if(startsWith($uri, "./")) $uri = substr($uri, 2, $length - 2);
    }
    return $uri;
}
function Block($needle)
{
    $needle = Sanitize($needle);
    return (startsWithBlocked($needle));
}
if(Block($_SERVER['REQUEST_URI']))
{
        $ip = $_SERVER['REMOTE_ADDR'];
        system("echo +$ip >> /proc/net/xt_recent/scandrop");
}
?>