Referrer spam is a kind of spamdexing (spamming aimed at search engines). The technique involves making repeated web site requests using a fake referrer url that points to the site the spammer wishes to advertise. Sites that publicize their access logs, including referrer statistics, will then end up linking to the spammer's site, which will in turn be indexed by the search engines as they crawl the access logs.

This benefits the spammer because of the free link, and also gives the spammer's site improved search engine placement due to link-counting algorithms that search engines use.

[edit] Technical solutions

As with e-mail spam, web site operators who receive unwanted referrer spam may respond using filtering and blocking.

A simple solution to render this form of spamming ineffective is to prevent the search engine spiders from crawling the site logs by moving them to a non-public area such as a password-protected area, by using a robot exclusion file, or by appending the nofollow value to the links.

[edit] See also

• Adversarial information retrieval
• Spam in blogs
• Referrer spoofing

[edit] External links

• A proposal on addressing referrer spam - technical overview and ideas for combatting the practice

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