I place this inside /etc/nginx/conf.d

httpblock.conf

#add to http {} block
map $http_referer $bad_referer {
	default 0;
	"~*event-tracking.com" 1;
	"~*theguardlan.com" 1;
	"~*free-share-buttons.com" 1;
	"~*free-social-buttons.com" 1;
	"~*buy-cheap-online.info" 1;
	"~*free-social-buttons.com" 1;
	"~*he-prod" 1;
	"~*fiverr.com" 1;
	"~*buttons-for-website.com" 1;
	"~*social-buttons.com" 1;
	"~*darodar.com" 1;
	"~*googlsucks.com" 1;
	"~*hulfingtonpost.com" 1;
	"~*semalt.com" 1;
	"~*4webmasters.org" 1;
	"~*best-seo-offer.com" 1;
	"~*buttons-for-your-website.com" 1;
	"~*anal-acrobats.hol.es" 1;
	"~*Get-Free-Traffic-Now.com" 1;
	"~*sanjosestartups.com" 1;
	"~*rankscanner.com" 1;
	"~*howtostopreferralspam.eu" 1;
	"~*100dollars-seo.com" 1;
	"~*trafficmonetize.org" 1;
	"~*4webmasters.org" 1;
	"~*webmonetizer.net" 1;
}