Ultrasurf

Ultrasurf

UltraSurf is a freeware Internet censorship circumvention product created by UltraReach Internet Corporation. The software enables its users to bypass censorship and firewalls using an HTTP proxy, and employs encryption protocols for privacy. The software was developed by Chinese dissidents as a means of allowing internet users to bypass the Great Firewall of China. It currently boasts as many as 11 million users worldwide. The tool has been lauded as "one of the most important free-speech tools on the Internet" by Wired magazine, and as the "best performing" circumvention tool by Harvard University in a 2007 study; a 2011 study by Freedom House ranked it fourth. Critics in the open source community have expressed concern about the software's closed-source nature and alleged security through obscurity design; UltraReach says their security considerations mean they prefer third party expert review to open source review.

Client Software

UltraSurf is free to download, and requires no installation. UltraSurf does not install any files on the user's computer, and leaves no registry edits after it exits.[5] In other words, it leaves no trace of its use. To fully remove the software from the computer, a user needs only to delete the exe file named u.exe. It is only available on a Windows platform, and runs through Internet Explorer by default, with an optional plug-in for Firefox. The UltraReach website notes that "Some anti-virus software companies misclassify UltraSurf as a malware or Trojan because UltraSurf encrypts the communications and circumvents internet censorship." Some security companies have agreed to whitelist UltraSurf.[8] According to Applebaum, the UltraSurf client uses anti-debugging techniques and also employs executable compression.[9] The client acts as a local proxy which communicates with the UltraReach network through what appears to be an obfuscated form of TLS/SSL.

UltraSurf Servers:

The software works by creating an encrypted HTTP tunnel between the user's computer and a central pool of proxy servers, enabling users to bypass firewalls and censorship.[5] UltraReach hosts all of its own servers.[5] The software makes use of sophisticated, proprietary anti-blocking technology to overcome filtering and censorship online.[5] According to Wired magazine, UltraSurf changes the "IP addresses of their proxy servers up to 10,000 times an hour."[2] On the server-side, a 2011 analysis found that the UltraReach network employed squid and ziproxy software, as well as ISC BIND servers bootstrapping for a wider network of open recursive DNS servers, the latter not under UltraReach control.[9] UltraSurf is designed primarily as an anti-censorship tool, but also offer privacy protections in the form of industry standard encryption, with an added layer of obfuscation built in.[1] UltraReach uses an internal content filter which blocks some sites, such as those deemed pornographic or otherwise offensive.[5] According to Wired magazine: "That's partly because their network lacks the bandwidth to accommodate so much data-heavy traffic, but also because Falun Gong frowns on erotica."[2] Additionally, the Falun Gong criticism website facts.org.cn, alleged to be operated by the Chinese government, is also unreachable through UltraSurf.