Sometimes you want to limit bots globally for all your sites in an nginx instance. These instructions illustrate a solution to this usesase.

1. Edit: /etc/nginx/nginx.conf and add the following block to the end of the http block:

## Global BOT Blocker ##
map $http_user_agent $_global_bot_blocker {
    default 0;
    ~*(google|bing|yandex|msnbot) 1;
    ~*(AltaVista|Googlebot|Slurp|BlackWidow|Bot|ChinaClaw|Custo|DISCo|Download|Demon|eCatch|EirGrabber|EmailSiphon|EmailWolf|SuperHTTP|Surfbot|WebWhacker) 1;
    ~*(Express|WebPictures|ExtractorPro|EyeNetIE|FlashGet|GetRight|GetWeb!|Go!Zilla|Go-Ahead-Got-It|GrabNet|Grafula|HMView|Go!Zilla|Go-Ahead-Got-It) 1;
    ~*(rafula|HMView|HTTrack|Stripper|Sucker|Indy|InterGET|Ninja|JetCar|Spider|larbin|LeechFTP|Downloader|tool|Navroad|NearSite|NetAnts|tAkeOut|WWWOFFLE) 1;
    ~*(GrabNet|NetSpider|Vampire|NetZIP|Octopus|Offline|PageGrabber|Foto|pavuk|pcBrowser|RealDownload|ReGet|SiteSnagger|SmartDownload|SuperBot|WebSpider) 1;
    ~*(Teleport|VoidEYE|Collector|WebAuto|WebCopier|WebFetch|WebGo|WebLeacher|WebReaper|WebSauger|eXtractor|Quester|WebStripper|WebZIP|Wget|Widow|Zeus) 1;
    ~*(Twengabot|htmlparser|libwww|Python|perl|urllib|scan|Curl|email|PycURL|Pyth|PyQ|WebCollector|WebCopy|webcraw) 1;
}

• The above can be adjusted to your preference
• The above config will block curl and wget unless you alter the 'User-Agent' header

2. In the location block of your site, add the following if ($_global_bot_blocker = 1) { return 403; }