http_user_agent 是客户的访问时使用的代理软件信息，一般都为浏览器，如chrome，firefox等。如果你通过程序进行访问，则在nginx logs中会保留获取到的地址，需要拒绝某些user-agent访问站点的时候，可以根据user-agent进行相关阻止配置，也就起到了防火墙的作用。
基本表达式：
(HTTrack|Apache-HttpClient|harvest|audit|dirbuster|pangolin|nmap|sqln|hydra|Parser|libwww|BBBike|sqlmap|w3af|owasp|Nikto|fimap|havij|zmeu|BabyKrokodil|netsparker|httperf| SF/)
扩充表达式：
(HTTrack|Apache-HttpClient|harvest|audit|dirbuster|pangolin|nmap|sqln|hydra|Parser|libwww|BBBike|sqlmap|w3af|owasp|Nikto|fimap|havij|zmeu|BabyKrokodil|netsparker|httperf|CheckMarkNetwork|Synapse|Nimbostratus-Bot|Dark|scraper|LMAO|Hakai|Gemini|Wappalyzer|masscan|crawler4j|Mappy|Center|eright|aiohttp|MauiBot|Crawler|researchscan|Dispatch|AlphaBot|Census|ips-agent|NetcraftSurveyAgent|ToutiaoSpider|EasyHttp|Iframely|sysscan|fasthttp|muhstik|DeuSu|mstshash|HTTP_Request|ExtLinksBot|package|SafeDNSBot|CPython|SiteExplorer|SSH|MegaIndex|BUbiNG|CCBot|NetTrack|Digincore|aiHitBot|SurdotlyBot|null|SemrushBot|Test|Copied|ltx71|Nmap|DotBot|AdsBot|InetURL|Pcore-HTTP|PocketParser|Wotbox|newspaper|DnyzBot|redback|PiplBot|SMTBot|WinHTTP|Auto Spider 1.0|GrabNet|TurnitinBot|Go-Ahead-Got-It|Download Demon|Go!Zilla|GetWeb!|GetRight|libwww-perl|Cliqzbot|MailChimp|SMTBot|Dataprovider|XoviBot|linkdexbot|SeznamBot|Qwantify|spbot|evc-batch|zgrab|Go-http-client|FeedDemon|JikeSpider|Indy Library|Alexa Toolbar|AskTbFXTV|AhrefsBot|CrawlDaddy|CoolpadWebkit|Java|UniversalFeedParser|ApacheBench|Microsoft URL Control|Swiftbot|ZmEu|jaunty|Python-urllib|lightDeckReports Bot|YYSpider|DigExt|YisouSpider|MJ12bot|EasouSpider|LinkpadBot|Ezooms| SF/)
注意:如果您不了解正则表达式，请不要随意修改规则内容
您可以添加或修改规则内容，但请使用正则表达式
内置规则允许修改，但不可以直接删除，您可以设置规则状态来定义防火墙是否使用此规则
