map $http_user_agent $uatype { default 'user'; ~*(googlebot|bingbot) 'good_bot'; ~*(nastybot|somebadscraper) 'ba

map $http_user_agent $uatype { default 'user'; ~*(googlebot|bingbot) 'good_bot'; ~*(nastybot|somebadscraper) 'bad_bot'; } You can also do something like this to rate limit instead of by IP address. Making all ‘bad_bots’ limited but not ‘good_bots’. I’m not dismissing the difficulty of the problem but there are multiple vectors that can identify these ‘bad_bots’.