PHPrbl – Eelco

Ever had those annoying referrer spammers ruin your website’s statistics? If you run a big website, or a weblog, you must be getting fed up with this blasted referrer spam.

You’re not alone, I have this problem as well and got fed up with the whole thing. After weeks of playing with the idea of blocking referrer spammers using rewrite rules, I got fed up wit the high amount of energy it would demand of me just to block IP addresses that seemed to be open proxies anyway.

Referrer spam

Referrer spam is, simply explained, a client leaving a fake referrer on your website. The statistics program that generates the referrer reports treats this referrer like it would treat any other referrer and list it in your website’s referrer list. These referrer spammers don’t just visit your site once, they visit it several times an hour, resulting in something like this. These referrers have nothing to do with my site whatsoever.

RBL

Upon digging a bit deeper into the muck that was created by this referrer spam, I discovered that most of the originating IP addresses were open proxies. A lot of these open proxies are listed by RBL lists that are primarily used by mailservers to block spammers.

This is where PHPrbl comes in, it checks the IP address of the visiting client against one or more RBL lists and will block the client if it is indeed listed.

I want it!

Okay, you can download version 0.4 of PHPrbl here.

Are there drawbacks

Yes, because PHPrbl needs to do a DNS lookup on a hostname, the loading of the page might be a bit slower, depending on the server the site is running on. On my own sites, I have not noticed any slowdown however. The prechecking option should improve performance.

Helping out

While I work on a way for people to submit IP addresses for my own RBL, you can help out by donating some money through PayPal :)

Mumbo Jumbo

This is free software, released under the GNU/GPL License.