.htaccess block semalt with wildcard regex

Question

I have the below rewrite rule to block semalt.com. It blocks all traffic referred by them (ie 1.semalt.com). Recently they create a new referrer url (semaltmedia.com). How can I modify the below code to block if they have a word before or after the word semalt with no space or period (ie semaltmedia.com)?

 RewriteCond %{HTTP_REFERER} semalt\.com [NC]

Answer 1

Try :

RewriteCond %{HTTP_REFERER} ^https?://(www\.)?.*semalt.*\.com [NC]
RewriteRule ^ - [F,L]

This returns a forbidden (403) message for a http referer of the following formats :

• http://semalt.com
• https://www.semalt.com
• http://foosemaltbar.com
• http://semalt.com/foo/bar