Nginx Lua Redis防止CC攻击实现原理：同一个外网IP、同一个网址(ngx.var.request_uri)、同一个客户端(http_user_agent)在某一段时间(CCseconds)内访问某个网址(ngx.var.request_uri)超过指定次数(CCcount)，则禁止这个外网IP+同一个客户端(md5(IP+ngx.var.http_user_agent)访问这个网址(ngx.var.request_uri)一段时间(blackseconds)。

该脚本使用lua编写(依赖nginx+lua)，将信息写到redis(依赖redis.lua)。

Nginx lua模块安装

重新编译nginx，安装lua模块，或者直接使用《OneinStack》安装OpenResty自带改模块

pushd /root/oneinstack/src
wget -c http://nginx.org/download/nginx-1.10.3.tar.gz
wget -c http://mirrors.linuxeye.com/oneinstack/src/openssl-1.0.2k.tar.gz
wget -c http://mirrors.linuxeye.com/oneinstack/src/pcre-8.39.tar.gz
wget -c http://luajit.org/download/LuaJIT-2.0.4.tar.gz
git clone https://github.com/simpl/ngx_devel_kit.git
git clone https://github.com/openresty/lua-nginx-module.git
tar xzf nginx-1.10.3.tar.gz
tar xzf openssl-1.0.2k.tar.gz
tar xzf pcre-8.39.tar.gz
tar xzf LuaJIT-2.0.4.tar.gz
pushd LuaJIT-2.0.4
make && make install
popd
pushd nginx-1.10.3
./configure --prefix=/usr/local/nginx --user=www --group=www --with-http_stub_status_module --with-http_v2_module --with-http_ssl_module --with-http_gzip_static_module --with-http_realip_module --with-http_flv_module --with-http_mp4_module --with-openssl=../openssl-1.0.2k --with-pcre=../pcre-8.39 --with-pcre-jit --with-ld-opt=-ljemalloc --add-module=../ngx_cache_purge-2.3 --add-module=../lua-nginx-module --add-module=../ngx_devel_kit
make
mv /usr/local/nginx/sbin/nginx{,_bk}
cp objs/nginx /usr/local/nginx/sbin
nginx -t #检查语法

加载redis.lua

mkdir /usr/local/nginx/conf/lua
cd /usr/local/nginx/conf/lua
wget https://github.com/openresty/lua-resty-redis/raw/master/lib/resty/redis.lua

#the Nginx bundle:
lua_package_path "/usr/local/nginx/conf/lua/redis.lua;;";

防止CC规则waf.lua

local get_headers = ngx.req.get_headers
local ua = ngx.var.http_user_agent
local uri = ngx.var.request_uri
local url = ngx.var.host .. uri
local redis = require 'redis'
local red = redis.new()
local CCcount = 20
local CCseconds = 60
local RedisIP = '127.0.0.1'
local RedisPORT = 6379
local blackseconds = 7200

if ua == nil then
    ua = "unknown"
end

if (uri == "/wp-admin.php") then
    CCcount=20
    CCseconds=60
end

red:set_timeout(100)
local ok, err = red.connect(red, RedisIP, RedisPORT)

if ok then
    red.connect(red, RedisIP, RedisPORT)

    function getClientIp()
        IP = ngx.req.get_headers()["X-Real-IP"]
        if IP == nil then
            IP = ngx.req.get_headers()["x_forwarded_for"]
        end
        if IP == nil then
            IP  = ngx.var.remote_addr
        end
        if IP == nil then
            IP  = "unknown"
        end
        return IP
    end

    local token = getClientIp() .. "." .. ngx.md5(url .. ua)
    local req = red:exists(token)
    if req == 0 then
        red:incr(token)
        red:expire(token,CCseconds)
    else
        local times = tonumber(red:get(token))
        if times >= CCcount then
            local blackReq = red:exists("black." .. token)
            if (blackReq == 0) then
                red:set("black." .. token,1)
                red:expire("black." .. token,blackseconds)
                red:expire(token,blackseconds)
                ngx.exit(503)
            else
                ngx.exit(503)
            end
            return
        else
            red:incr(token)
        end
    end
    return
end

Nginx虚拟主机加载waf.lua

在虚拟主机配置文件/usr/local/nginx/conf/vhost/oneinstack.com.conf

access_by_lua_file "/usr/local/nginx/conf/lua/waf.lua";

测试

一分钟之内，一个页面快速点击20次以上，登录redis，看到black开通的key即被禁止访问（nginx 503）