PHP中检测IP是否是内网IP的三个方法

if (filter_var(
        $_SERVER['REMOTE_ADDR'], 
        FILTER_VALIDATE_IP, 
        FILTER_FLAG_NO_PRIV_RANGE|FILTER_FLAG_NO_RES_RANGE
    )) {
    header('HTTP/1.0 403 Forbidden');
    die('禁止外网访问');
}

function ip_is_private($ip){
    $pri_addrs = array(
        '10.0.0.0|10.255.255.255',
        '172.16.0.0|172.31.255.255',
        192.168.0.0|192.168.255.255',
        '169.254.0.0|169.254.255.255',
        '127.0.0.0|127.255.255.255'
    );
    $long_ip = ip2long($ip);
    if($long_ip != -1) {
    foreach($pri_addrs AS $pri_addr) {
        list($start, $end) = explode('|', $pri_addr);
        // IF IS PRIVATE
        if($long_ip >= ip2long($start) && $long_ip <= ip2long($end))
            return (TRUE);
        }
    }
    return (FALSE);
}

function ip_is_internal($ip) { 
        $ip = ip2long($ip);
        if (!$ip) {
                return false;
        }
        $net_local = ip2long('127.255.255.255') >> 24; //127.x.x.x
        $net_a = ip2long('10.255.255.255') >> 24; //A类网预留ip的网络地址 
        $net_b = ip2long('172.31.255.255') >> 20; //B类网预留ip的网络地址 
        $net_c = ip2long('192.168.255.255') >> 16; //C类网预留ip的网络地址
        return $ip >> 24 === $net_local || $ip >> 24 === $net_a 
                || $ip >> 20 === $net_b || $ip >> 16 === $net_c; 
}