Cloudflare中firewall的编写方法

简单介绍

首先帮商家打个广告,博客使用的睿数据www.ruidata.net ,他家是阿里云代理,通过他家买阿里云服务器9折

​ 这篇文章中说到博客一直在使用CloudFlare提供SSL服务和防火墙服务。SSL并没有什么好说的,今天简单介绍一下我是如何写Cloudflare中的防火墙规则。

firewall,也就是我们所说的防火墙规则。我们可以先看下效果

Cloudflare中firewall的编写方法

如图所示,在2.13号一天,防火墙为我们拦截了上亿条的恶意请求。免费套餐有5条的额度,对于一般用户我觉得已经足够了,如果你的网站结构过于复杂,还请你升级套餐,以寻求更多规则额度。

​ 我们可以找到的官方文档如下:https://developers.cloudflare.com/firewall/cf-firewall-rules/,请先观看此文档,再看本文。如果你看完文档的话,你会发现拦截恶意请求其实很简单(当然需要你对http请求有一定了解)。看不懂也没关系,本文将大致讲解一下常用字段。防火墙支持的字段比一般编程语言更多,基于应用层+网络层。

基础字段

  • AS Num

    ​ 通常缩写为asn,指的是某一个IP管理系统所分配到的IP,如果你看到大量恶意请求来自同一个asn,那就可以对这个asn直接做处理,亦或者你想屏蔽某IDC机房,也可以直接查到他的asn号。 可以用在线工具来查询 asn,例如 ipip.net https://tools.ipip.net/as.php;也可以下载一个离线库来查询某IP的asn信息,例如 https://iptoasn.com/

  • Cookie

    ​ 服务端用来标识用户身份的手段,如果不了解,就不用做处理。

  • Country

    ​ 访客IP对应的国家,可以用来做访客区域限制。

  • Hostname

    ​ 访问的主机名,也就是域名。因为CF是域名接入,子域名也会走这一段,如果你需要针对某子域名写规则,则需要用到这个字段。

  • IP Address

    ​ 访客IP地址。

  • Referer

    ​ 页面来源,详情可以看 百度百科,可以做防盗链,也可以限制API不被滥用。

  • Request Method

    ​ 页面请求方式,GET、POST、HEAD等这些。我们都知道,POST请求是不被缓存的,所以可能会被坏人利用这一手段来进行CC攻击。所对应的防御手段就是在不需要使用其他请求方式的时候只开启GET。

  • SSL/HTTPS

    ​ 是否启用SSL。

  • URI Full

    ​ 页面完整地址。获取到的是这个 https://www.baidu.com/s?ie=utf-8&wd=%E5%9D%8F%E7%94%B7%E5%AD%A9

  • URI

    ​ 页面地址。如果上面的URL,只能获取到 /s?ie=utf-8&wd=%E5%9D%8F%E7%94%B7%E5%AD%A9 ,也就是去掉了协议+主机名。

  • URI PATH

    ​ 页面路径。上面基础再去掉请求参数,获取到 /s

  • URI Query String

    ​ 请求参数。获取到的就是 ie=utf-8&wd=%E5%9D%8F%E7%94%B7%E5%AD%A9

  • HTTP Version

    ​ HTTP版本。不常用。

  • User Agent

    ​ 用户代理,缩写为UA。可以用来屏蔽掉非正常用户。这里我用来屏蔽一些程序访问,例如 (http.user_agent contains "curl") or (http.user_agent contains "requests") or (http.user_agent contains "python") or (http.user_agent contains "php") or (http.user_agent contains "java") or (http.user_agent contains "urllib") or (http.user_agent contains "Java") or (http.user_agent contains "Ruby") or (http.user_agent contains "Go-http-client") or (not http.user_agent contains "/")

  • X-Forwarded-For

    ​ XFF头,使用了代理或者CDN后常添加到这里。详见百度百科

  • Known Bots

    ​ 已知爬虫。这里是CF已知的搜索引擎爬虫,我们可以用它来给搜索引擎爬虫加白。

  • Threat Score

    ​ 风险指数、安全分数。可选为0-100,0为最低。越大表示该IP风险越高。

基本逻辑

可以看这里 https://developers.cloudflare.com/firewall/cf-firewall-rules/fields-and-expressions/,基本类同于程序语法。

相应动作

ActionDescription
BypassAllows user to dynamically disable Cloudflare security features for a requestAvailable to all plansMatching requests exempt from evaluation by a user-defined list containing one or more of the following Cloudflare Firewall products/features:User-agent BlockingBrowser Integrity CheckHotlinking ProtectionSecurity Level (IP Reputation)Rate LimitingZone Lockdown (PRO, BIZ, ENT)WAF Managed Rules (PRO, BIZ, ENT)Requests which match the Bypass action are still subject to evaluation (and thus a challenge or block) within Firewall Rules, based on the order of execution.To stop a bypassed request from further evaluation within Firewall Rules, you must create a new rule using the same expression and the Allow action immediately below the Bypass rule.//让请求不受某条规则的限制
AllowMatching requests are exempt from challenge and block actions triggered by other Firewall Rules content.The scope of the Allow action is limited to Firewall Rules; matching requests are not exempt from action by other Cloudflare Firewall products, such as IP Access Rules, WAF, etc.Matched requests will be mitigated if they are part of a DDoS attack.//允许该请求
Challenge (Captcha)Useful for ensuring that the visitor accessing the site is human, not automatedThe client that made the request must pass a Captcha Challenge.If successful, Cloudflare accepts the matched request; otherwise, it is blocked.//输入验证码
JS ChallengeUseful for ensuring that bots and spam cannot access the requested resource; browsers, however, are free to satisfy the challenge automatically.The client that made the request must pass a Cloudflare Javascript Challenge before proceeding.If successful, Cloudflare accepts the matched request; otherwise, it is blocked.//五秒盾
BlockMatching requests are denied access to the site.//直接阻止访问

完整可以看这里 <https://developers.cloudflare.com/firewall/cf-firewall-rules/actions/ >。

开始实战

​ 下面介绍我是如何写的,由于博客是纯静态的,所以我并不担心会出现服务器被入侵的问题。所以我编写的规则大部分是针对恶意(非真实)用户的拦截。

  • 屏蔽掉自动化/程序访问,这里我直接选择block

    (http.user_agent contains "curl") or (http.user_agent contains "requests") or (http.user_agent contains "python") or (http.user_agent contains "php") or (http.user_agent contains "java") or (http.user_agent contains "urllib") or (http.user_agent contains "Java") or (http.user_agent contains "Ruby") or (http.user_agent contains "Go-http-client") or (not http.user_agent contains "/")

  • 验证可能存在风险的请求,选择Challenge (Captcha)(由于我的博客不需要接收传参,也不需要其他类型请求。如果你不是纯静态,请加白名单!!!)

    (http.request.full_uri contains "?") or (http.request.method ne "GET") or (cf.threat_score gt 10)

  • 放行已知蜘蛛,选择Allow

    (cf.client.bot)

 

版权声明:东成西就 发表于 2020-07-19 16:38:30。
转载请注明:Cloudflare中firewall的编写方法 | 云知道

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