本文介绍使用openresty来实现防cc攻击的功能。openresty官网http://openresty.org/cn/index.html。下面是防cc攻击的流程图。
根据流程图,我们知道防cc攻击主要包括两部分,一是限制请求速度,二是给用户发送js跳转代码进行验证请求是否合法。
一、安装依赖 centos:
yum install readline-devel pcre-devel openssl-devel
ubuntu:
apt-get install libreadline-dev libncurses5-dev libpcre3-dev libssl-dev perl
二、luajit安装
cd /tmp/git clone http://luajit.org/git/luajit-2.0.gitcd luajit-2.0/make && make installln -sf luajit-2.0.0-beta10 /usr/local/bin/luajitln -sf /usr/local/lib/libluajit-5.1.so.2 /usr/lib/三、openresty安装
cd /tmpwget http://agentzh.org/misc/nginx/ngx_openresty-1.2.4.13.tar.gztar xzf ngx_openresty-1.2.4.13.tar.gzcd ngx_openresty-1.2.4.13/./configure --prefix=/usr/local/openresty --with-luajitmake && make install四、nginx配置nginx.conf:
http{[......]lua_shared_dict limit 10m;lua_shared_dict jsjump 10m; server {#lua_code_cache off; listen 80; server_name www.centos.bz; location / {default_type text/html;content_by_lua_file "/usr/local/openresty/nginx/conf/lua"; } location @cc { internal; root html; index index.html index.htm; } }}/usr/local/openresty/nginx/conf/lua文件:
local ip = ngx.var.binary_remote_addrlocal limit = ngx.shared.limitlocal req,_=limit:get(ip)if req then if req > 20 then ngx.exit(503) else limit:incr(ip,1) endelse limit:set(ip,1,10)endlocal jsjump = ngx.shared.jsjumplocal uri = ngx.var.request_urilocal jspara,flags=jsjump:get(ip)local args = ngx.req.get_uri_args()if jspara then if flags then ngx.exec("@cc") else if args["jskey"] and args["jskey"]==tostring(jspara) then jsjump:set(ip,jspara,3600,1) ngx.exec("@cc") else local url='' if ngx.var.args then url=ngx.var.scheme.."://"..ngx.var.host..ngx.var.request_uri.."&jskey="..jspara else url=ngx.var.scheme.."://"..ngx.var.host..ngx.var.request_uri.."?jskey="..jspara end local jscode="<script>window.location.href='"..url.."';</script>" ngx.say(jscode) end endelse local random=math.random(100000,999999) jsjump:set(ip,random,60) local url='' if ngx.var.args then url=ngx.var.scheme.."://"..ngx.var.host..ngx.var.request_uri.."&jskey="..random else url=ngx.var.scheme.."://"..ngx.var.host..ngx.var.request_uri.."?jskey="..random end local jscode="<script>window.location.href='"..url.."';</script>" ngx.say(jscode)endlua代码部分解释:
1、1-12行是限速功能实现,第5和第10行表示10秒钟内容最多只能请求20次。
2、14-48行是验证部分,24行中的3600表示验证通过后,白名单时间为3600秒,即1小时。
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