An Extensive Evaluation of the Internet’s Open Proxies Akshaya Mani∗ Tavish Vaidya∗ Georgetown University Georgetown University
[email protected] [email protected] David Dworken Micah Sherr Northeastern University Georgetown University
[email protected] [email protected] ABSTRACT 1 INTRODUCTION Open proxies forward traffic on behalf of any Internet user. Listed Open proxy servers are unrestricted proxies that allow access from on open proxy aggregator sites, they are often used to bypass geo- any Internet user. Open proxies are fairly prevalent on the Internet, graphic region restrictions or circumvent censorship. Open proxies and several websites are devoted to maintaining large lists of avail- sometimes also provide a weak form of anonymity by concealing able open proxies. In contrast to VPNs [29] and some (but not all) the requestor’s IP address. anonymity systems, open proxies are generally easy for users to To better understand their behavior and performance, we con- use, requiring only minimal configuration changes (e.g., adjusting ducted a comprehensive study of open proxies, encompassing more “network settings”) rather than the installation of new software. than 107,000 listed open proxies and 13M proxy requests over a 50 As surveyed in this paper, there is a variety of types of open prox- day period. While previous studies have focused on malicious open ies, with differing capabilities. This leads to variation in how proxies proxies’ manipulation of HTML content to insert/modify ads, we are used in practice. Clearly, open proxies have been (mis)used for provide a more broad study that examines the availability, success malicious purposes, including (but not limited to) sending spam, rates, diversity, and also (mis)behavior of proxies.