CREATE TABLE `all_visits` (
`ip` varchar(15) DEFAULT NULL,
`date` int(11) DEFAULT NULL,
INDEX (`date` Desc)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

<?php
if (!empty($_SERVER['HTTP_CLIENT_IP']))
$ip=$_SERVER['HTTP_CLIENT_IP'];
elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
$ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
else $ip=$_SERVER['REMOTE_ADDR'];
$bot=$_SERVER['HTTP_USER_AGENT'];

if (strstr($_SERVER['HTTP_USER_AGENT'], 'Yandex')) {$bot='Allowed_bot';}
elseif (strstr($_SERVER['HTTP_USER_AGENT'], 'Google')) {$bot='Allowed_bot';}
elseif (strstr($_SERVER['HTTP_USER_AGENT'], 'Yahoo')) {$bot='Allowed_bot';}
elseif (strstr($_SERVER['HTTP_USER_AGENT'], 'Mail.Ru')) {$bot='Allowed_bot';}
elseif (strstr($_SERVER['HTTP_USER_AGENT'], 'Bing')) {$bot='Allowed_bot';}

if ($bot!='Allowed_bot') {

$link=mysql_connect("IP-адрес-MYSQL","Login_mysql","Password_mysql") or die("Could not connect: ".mysql_error());
mysql_select_db("ИМЯ_БД", $link);

$result=mysql_query("INSERT INTO all_visits (ip,date)
VALUES ('".$ip."','".time(true)."')");
$result=mysql_query("SELECT count(1) FROM all_visits
WHERE (ip='".$ip."' and date>'".(time(true)-5)."')", $link);
$count_visit=mysql_fetch_array($result);

if ($count_visit[0]>30) {
$file_htaccess=".htaccess";
$start_line=0;

$lines=file($file_htaccess);
for ($n=0; $n<=count($lines)-1; $n++) {
$lines_htaccess[]=$lines[$n];
if ($lines[$n] == "<Limit GET POST> \r\n") {
$lines_htaccess[]=$lines[$n+1]; //order allow,deny
$start_line=$n+2;
break;
}
}

if ($start_line!=0) {
$lines_htaccess[]=" deny from ".$ip."\r\n";
for ($n=$start_line; $n<=count($lines); $n++) $lines_htaccess[]=$lines[$n];
} else {
$lines_htaccess = $lines;
$lines_htaccess[]="<Limit GET POST> \r\n";
$lines_htaccess[]=" order allow,deny \r\n";
$lines_htaccess[]=" deny from ".$ip."\r\n";
$lines_htaccess[]=" allow from all \r\n";
$lines_htaccess[]="</Limit> \r\n\r\n";
}

file_put_contents($file_htaccess, $lines_htaccess);
}
}
?>

# Описываем зону (slimits), в которой будут храниться состояния сессий. Зона размером 1 Мб может хранить около 32000 состояний, мы устанавливаем ее размер равным 5 Мб
limit_zone slimits $binary_remote_addr 5m;
# Задаем максимальное количество одновременных соединений для одной сессии. По сути, это число задает максимальное количество соединений с одного IP
limit_conn slimits 5;

limit_zone slimits $binary_remote_addr 5m;

$binary_remote_addr

user www;
worker_processes 2;
pid /var/run/nginx.pid;

events {
use kqueue;
worker_connections 1024;
multi_accept on;
}
http {
include mime.types;
default_type application/octet-stream;
large_client_header_buffers 4 4k;
tcp_nopush on;
sendfile on;
output_buffers 32 512k;
sendfile_max_chunk 128k;
postpone_output 1460;
tcp_nodelay on;
limit_zone lconn $binary_remote_addr 5m;
fastcgi_intercept_errors on;
server_names_hash_bucket_size 64;
client_max_body_size 15m;
server {
listen IP_своего_веб_сервера;
server_name DNS_имя_своего_веб_сервера;
limit_conn lconn 5;
location / {
root /usr/local/www/папка_с_содержимым_сайта;
index index.html index.htm;
}
}
}

limit_conn_zone $binary_remote_addr zone=perip:10m;
limit_conn perip 100;

limit_req_zone $binary_remote_addr zone=dynamic:10m rate=2r/s;
limit_req zone=dynamic burst=10 nodelay;

server {
.....................
location / {

....................................
}
}

server {
limit_conn_zone $binary_remote_addr zone=perip:10m;
limit_req_zone $binary_remote_addr zone=dynamic:10m rate=2r/s;

location / {
limit_conn perip 100;
limit_req zone=dynamic burst=10 nodelay;
}
}