Why Detect Proxy Servers?
Anonymity is readily obtained online. Anyone can hide their identity using a proxy server, a virtual private network, Tor or other anonymity network. Such systems provide a useful service for many users but pose significant challenges for webmasters who need to control access to their websites, know their customers, and fight fraud. A webmaster can easily become overwhelmed by the hundreds of thousands of proxies online and the vectors for abuse they present.
Common methods of blocking proxies include manual and automated solutions. Manually blocking proxies requires both an understanding of the many types of proxies in use on the Internet as well as an up-to-date list of proxy IP addresses. There are several websites that publish blacklists, however, they may not be reliable or useful for a particular purpose. Approximately 30% of proxy IP addresses change each day, making it difficult and time consuming to maintain a good blacklist. Once you have a blacklist, the next step is to insert it into a firewall or .htaccess file. The way that a blacklist is used can have a negative impact on the performance of a website.