Semalt, Bad Bot
Over the past months I’ve noticed an increase in traffic referred from semalt.com, an outfit that claims to provide:
Professional keyword ranking monitoring seo service with competitor analysis.
What they actually do is send a flood of unwanted hits to the site from their SPAM bot, followed by foreign traffic referrals from non targeted visitors. This can hurt your analysis of traffic by skewing results, as well as using server bandwidth. But getting rid of this bad bot proved to be problematic.
Filtering Google Analytics Reports
Use a custom filter on the Analytics account to exclude Referrals from bad bots
The first step I take on all sites I work with is to filter all traffic referred by semalt.com. See the screenshot.
That will stop tracking of the unwanted traffic, but what I really want to do is to deny them from accessing the site at all. Typically this is done by adding a directive to the robots.txt file. That won’t work in this case, as their crawlers don’t follow robots.txt directives.
Another method that has been recommended by Semalt themselves is to use their opt-out removal tool. DON’T DO THIS! The tool is used to gather a list of active webmasters to whom they will send further spam.
You should never have to request removal from a service you didn’t subscribe to in the first place. Adding your website address this way just lets the bad bots know this is a valid target.
Instead, adding a few lines of code to the .htaccess file takes care of it:
<IfModule mod_rewrite.c>
RewriteEngine On
# block visitors referred from semalt.com
RewriteCond %{HTTP_REFERER} semalt.com [NC]
RewriteRule .* - [F]
</IfModule>
Another bit of code that works
RewriteCond %{HTTP_REFERER} (.)?(semalt).com$ [NC]
RewriteRule . - [F]