最近网站访问非常慢，cpu 占用非常高，服务器负载整体也非常高，打开日志发现有很多不知名的蜘蛛一直在爬行我的站点，根据经验肯定是这里的问题，于是根据我的情况写了规则做了屏蔽，屏蔽后负载降下来了，下面整理下 iis 及 nginx 及 apache 环境下如何屏蔽不知名的蜘蛛 ua。

注意（请根据自己的情况调整删除或增加 ua 信息，我提供的规则中包含了不常用的蜘蛛 ua，几乎用不着，若您的网站比较特殊，需要不同的蜘蛛爬取，建议仔细分析规则，将指定 ua 删除即可）

屏蔽后的效果

1、我网站是 nginx,下面是我的屏蔽规则,将规则添加到配置文件的 server 段里面,当这些蜘蛛来抓取时会返回 444；

if ($http_user_agent ~ "MegaIndex|MegaIndex.ru|BLEXBot|Qwantify|qwantify|semrush|Semrush|serpstatbot|hubspot|python|Bytespider|Go-http-client|Java|PhantomJS|SemrushBot|Scrapy|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|mail.RU|perl|Python|Wget|Xenu|ZmEu|^$" )
{
    return 444;
}

2、IIS7/IIS8/IIS10 及以上 web 服务请在网站根目录下创建 web.config 文件,并写入如下代码即可;

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="Block spider">
<match url="(^robots.txt$)" ignoreCase="false" negate="true" />
<conditions>
<add input="{HTTP_USER_AGENT}" pattern="MegaIndex|MegaIndex.ru|BLEXBot|Qwantify|qwantify|semrush|Semrush|serpstatbot|hubspot|python|Bytespider|Go-http-client|Java|PhantomJS|SemrushBot|Scrapy|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|mail.RU|perl|Python|Wget|Xenu|ZmEu|^$"
ignoreCase="true" />
</conditions>
<action type="AbortRequest" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>

3、IIS6 请在 isapi 重写组件中添加规则

#Block spider
RewriteCond %{HTTP_USER_AGENT} (MegaIndex|MegaIndex.ru|BLEXBot|Qwantify|qwantify|semrush|Semrush|serpstatbot|hubspot|python|Bytespider|Go-http-client|Java|PhantomJS|SemrushBot|Scrapy|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|mail.RU|perl|Python|Wget|Xenu|ZmEu|^$) [NC]
RewriteRule !(^/robots.txt$) - [F]

4、apache 请在.htaccess 文件中添加如下规则即可：

<IfModule mod_rewrite.c>
RewriteEngine On
#Block spider
RewriteCond %{HTTP_USER_AGENT} "MegaIndex|MegaIndex.ru|BLEXBot|Qwantify|qwantify|semrush|Semrush|serpstatbot|hubspot|python|Bytespider|Go-http-client|Java|PhantomJS|SemrushBot|Scrapy|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|mail.RU|perl|Python|Wget|Xenu|ZmEu|^$" [NC]
RewriteRule !(^robots\.txt$) - [F]
</IfModule>

来源：https://blog.tag.gg/showinfo-36-35757-0.html