Kinda long, so I’m putting it in spoilers. This applies to Nginx, but you can probably adapt it to other reverse proxies.
Create a file to hold the mappings and store it somewhere you can include it from your other configs. I named mine map-bot-user-agents.conf
Here, I’m doing a regex comparison against the user agent ($http_user_agent) and mapping it to either a 0 (default/false) or 1 (true) and storing that value in the variable $ua_disallowed. The run-on string at the bottom was inherited from another admin I work with, and I never bothered to split it out.
Once you have a mapping file setup, you’ll need to do something with it. This applies at the virtual host level and should go inside the server block of your configs (except the include for the mapping config.).
This assumes your configs are in conf.d/ and are included from nginx.conf.
The map-bot-user-agents.conf is included above the server block (since it’s an http level config item) and inside server, we look at the $ua_disallowedvalue where 0=false and 1=true (the values are set in the map).
You could also do the mapping in the base nginx.conf since it doesn’t do anything on its own.
If the $ua_disallowed value is 1 (true), we immediately return an HTTP 444. The 444 status code is an Nginx thing, but it basically closes the connection immediately and wastes no further time/energy processing the request. You could, optionally, redirect somewhere, return a different status code, or return some pre-rendered LLM-generated gibberish if your bot list is configured just for AI crawlers (because I’m a jerk like that lol).
Example site1.conf
include conf.d/includes/map-bot-user-agents.conf;
server {
server_name example.com;
...
# Deny disallowed user agentsif ($ua_disallowed) {
return 444;
}
location / {
...
}
}
I just include the map-bot-user-agents.conf in my base nginx.conf so it’s available to all of my virtual hosts.
When I want to enforce the bot blocking on one or more virtual host (some I want to leave open to bots, others I don’t), I just include a deny-disallowed.conf in the server block of those.
deny-disallowed.conf
# Deny disallowed user agentsif ($ua_disallowed) {
return 444;
}
site.conf
server {
server_name example.com;
...
include conf.d/includes/deny-disallowed.conf;
location / {
...
}
}
Yeah, if’s are weird in Nginx. The rule of thumb I’ve always gone by is that you shouldn’t try to if on variables directly unless they’re basically pre-processed to a boolean via a map (which is what the user agent map does).
Teach me oh wise one
Kinda long, so I’m putting it in spoilers. This applies to Nginx, but you can probably adapt it to other reverse proxies.
map-bot-user-agents.confHere, I’m doing a regex comparison against the user agent (
$http_user_agent) and mapping it to either a0(default/false) or1(true) and storing that value in the variable$ua_disallowed. The run-on string at the bottom was inherited from another admin I work with, and I never bothered to split it out.'map-bot-user-agents.conf'
# Map bot user agents map $http_user_agent $ua_disallowed { default 0; "~CCBot" 1; "~ClaudeBot" 1; "~VelenPublicWebCrawler" 1; "~WellKnownBot" 1; "~Synapse (bot; +https://github.com/matrix-org/synapse)" 1; "~python-requests" 1; "~bitdiscovery" 1; "~bingbot" 1; "~SemrushBot" 1; "~Bytespider" 1; "~AhrefsBot" 1; "~AwarioBot" 1; "~GPTBot" 1; "~DotBot" 1; "~ImagesiftBot" 1; "~Amazonbot" 1; "~GuzzleHttp" 1; "~DataForSeoBot" 1; "~StractBot" 1; "~Googlebot" 1; "~Barkrowler" 1; "~SeznamBot" 1; "~FriendlyCrawler" 1; "~facebookexternalhit" 1; "~*(?i)(80legs|360Spider|Aboundex|Abonti|Acunetix|^AIBOT|^Alexibot|Alligator|AllSubmitter|Apexoo|^asterias|^attach|^BackDoorBot|^BackStreet|^BackWeb|Badass|Bandit|Baid|Baiduspider|^BatchFTP|^Bigfoot|^Black.Hole|^BlackWidow|BlackWidow|^BlowFish|Blow|^BotALot|Buddy|^BuiltBotTough| ^Bullseye|^BunnySlippers|BBBike|^Cegbfeieh|^CheeseBot|^CherryPicker|^ChinaClaw|^Cogentbot|CPython|Collector|cognitiveseo|Copier|^CopyRightCheck|^cosmos|^Crescent|CSHttp|^Custo|^Demon|^Devil|^DISCo|^DIIbot|discobot|^DittoSpyder|Download.Demon|Download.Devil|Download.Wonder|^dragonfl y|^Drip|^eCatch|^EasyDL|^ebingbong|^EirGrabber|^EmailCollector|^EmailSiphon|^EmailWolf|^EroCrawler|^Exabot|^Express|Extractor|^EyeNetIE|FHscan|^FHscan|^flunky|^Foobot|^FrontPage|GalaxyBot|^gotit|Grabber|^GrabNet|^Grafula|^Harvest|^HEADMasterSEO|^hloader|^HMView|^HTTrack|httrack|HTT rack|htmlparser|^humanlinks|^IlseBot|Image.Stripper|Image.Sucker|imagefetch|^InfoNaviRobot|^InfoTekies|^Intelliseek|^InterGET|^Iria|^Jakarta|^JennyBot|^JetCar|JikeSpider|^JOC|^JustView|^Jyxobot|^Kenjin.Spider|^Keyword.Density|libwww|^larbin|LeechFTP|LeechGet|^LexiBot|^lftp|^libWeb| ^likse|^LinkextractorPro|^LinkScan|^LNSpiderguy|^LinkWalker|msnbot|MSIECrawler|MJ12bot|MegaIndex|^Magnet|^Mag-Net|^MarkWatch|Mass.Downloader|masscan|^Mata.Hari|^Memo|^MIIxpc|^NAMEPROTECT|^Navroad|^NearSite|^NetAnts|^Netcraft|^NetMechanic|^NetSpider|^NetZIP|^NextGenSearchBot|^NICErs PRO|^niki-bot|^NimbleCrawler|^Nimbostratus-Bot|^Ninja|^Nmap|nmap|^NPbot|Offline.Explorer|Offline.Navigator|OpenLinkProfiler|^Octopus|^Openfind|^OutfoxBot|Pixray|probethenet|proximic|^PageGrabber|^pavuk|^pcBrowser|^Pockey|^ProPowerBot|^ProWebWalker|^psbot|^Pump|python-requests\/|^Qu eryN.Metasearch|^RealDownload|Reaper|^Reaper|^Ripper|Ripper|Recorder|^ReGet|^RepoMonkey|^RMA|scanbot|SEOkicks-Robot|seoscanners|^Stripper|^Sucker|Siphon|Siteimprove|^SiteSnagger|SiteSucker|^SlySearch|^SmartDownload|^Snake|^Snapbot|^Snoopy|Sosospider|^sogou|spbot|^SpaceBison|^spanne r|^SpankBot|Spinn4r|^Sqworm|Sqworm|Stripper|Sucker|^SuperBot|SuperHTTP|^SuperHTTP|^Surfbot|^suzuran|^Szukacz|^tAkeOut|^Teleport|^Telesoft|^TurnitinBot|^The.Intraformant|^TheNomad|^TightTwatBot|^Titan|^True_Robot|^turingos|^TurnitinBot|^URLy.Warning|^Vacuum|^VCI|VidibleScraper|^Void EYE|^WebAuto|^WebBandit|^WebCopier|^WebEnhancer|^WebFetch|^Web.Image.Collector|^WebLeacher|^WebmasterWorldForumBot|WebPix|^WebReaper|^WebSauger|Website.eXtractor|^Webster|WebShag|^WebStripper|WebSucker|^WebWhacker|^WebZIP|Whack|Whacker|^Widow|Widow|WinHTTrack|^WISENutbot|WWWOFFLE|^ WWWOFFLE|^WWW-Collector-E|^Xaldon|^Xenu|^Zade|^Zeus|ZmEu|^Zyborg|SemrushBot|^WebFuck|^MJ12bot|^majestic12|^WallpapersHD)" 1; }Once you have a mapping file setup, you’ll need to do something with it. This applies at the virtual host level and should go inside the
serverblock of your configs (except the include for the mapping config.).This assumes your configs are in conf.d/ and are included from nginx.conf.
The
map-bot-user-agents.confis included above theserverblock (since it’s anhttplevel config item) and insideserver, we look at the$ua_disallowedvalue where 0=false and 1=true (the values are set in the map).You could also do the mapping in the base
nginx.confsince it doesn’t do anything on its own.If the
$ua_disallowedvalue is 1 (true), we immediately return an HTTP 444. The444status code is an Nginx thing, but it basically closes the connection immediately and wastes no further time/energy processing the request. You could, optionally, redirect somewhere, return a different status code, or return some pre-rendered LLM-generated gibberish if your bot list is configured just for AI crawlers (because I’m a jerk like that lol).Example site1.conf
include conf.d/includes/map-bot-user-agents.conf; server { server_name example.com; ... # Deny disallowed user agents if ($ua_disallowed) { return 444; } location / { ... } }So I would need to add this to every subdomain conf file I have? Preciate you!
I just include the
map-bot-user-agents.confin my basenginx.confso it’s available to all of my virtual hosts.When I want to enforce the bot blocking on one or more virtual host (some I want to leave open to bots, others I don’t), I just include a
deny-disallowed.confin theserverblock of those.deny-disallowed.conf
# Deny disallowed user agents if ($ua_disallowed) { return 444; }site.conf
Okay yeah I was thinking my base domain conf but that’s even better.
I’ve always been told to be scared about
ifs in nginx configsYeah,
if’s are weird in Nginx. The rule of thumb I’ve always gone by is that you shouldn’t try toifon variables directly unless they’re basically pre-processed to a boolean via amap(which is what the user agent map does).