computer science

Ultrasurf

Ultrasurf is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ultrasurf rather than just read about it. In short: UltraSurf is a closed-source freeware Internet censorship circumvention product created by UltraReach Internet Corporation. The software bypasses Internet censorship and firewalls using an HTTP proxy server, and employs encryption protocols for privacy.

Key takeaways

Ultrasurf belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ultrasurf to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ultrasurf from memory before moving on to harder problems.

Reference excerpt

UltraSurf is a closed-source freeware Internet censorship circumvention product created by UltraReach Internet Corporation. The software bypasses Internet censorship and firewalls using an HTTP proxy server, and employs encryption protocols for privacy. The software was developed by two different groups of Falun Gong practitioners at the same time, one starting in the US in 2002 by expatriate Chinese. The software was designed as a means of allowing internet users to bypass the Great Firewall of China. In 2011, UltraReach claimed to have as many as 11 million users worldwide. UltraSurf is proprietary software; critics in the open-source community have expressed concern about the software's closed-source nature and alleged security through obscurity design.

Overview In 2001, UltraReach was founded by members of Falun Gong. UltraSurf was created to allow internet users in China to evade government censorship and monitoring. In 2011 UltraSurf reported over eleven million users worldwide. During the Arab Spring, UltraReach recorded a 700 percent spike in traffic from Tunisia. Similar traffic spikes occurred during times of unrest in other regions, such as Tibet and Burma during the Saffron Revolution. However, a study by the United States Department of State found a very low level of usage of the software as of 2021, partially due to the software only being available on Windows.

Government Funding UltraSurf has received significant funding from the U.S. government. Originally, funding was provided through the U.S. State Department as well as the Broadcasting Board of Governors, which administered Voice of America and Radio Free Asia. However, this funding was revoked due to UltraSurf's refusal to comply with independent security audits. In 2020, when Michael Pack was appointed as the head of the U.S. Agency for Global Media by Donald Trump, Pack and several conservative allies pushed for additional funding for UltraSurf through the Open Technology Fund, despite use of closed-source code and low number of users. UltraSurf was awarded $1.8 million in funding under Pack, despite the objections of several high-ranking officials who were subsequently fired. Pack's actions were later referred to the Inspector General of the Department of State as part of a criminal conspiracy.

Operation

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. 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 Windows, runs through Internet Explorer by default, and has an optional plug-in for Firefox and Chrome. 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. According to Appelbaum, the UltraSurf client uses anti-debugging techniques and also employs executable compression. 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. UltraReach hosts all of its own servers. The software makes use of sophisticated, proprietary anti-blocking technology to overcome filtering and censorship online. According to Wired magazine, UltraSurf changes the "IP addresses of their proxy servers up to 10,000 times an hour." 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. UltraSurf is designed primarily as an anti-censorship tool but also offers privacy protections in the form of industry standard encryption, with an added layer of obfuscation built in. UltraReach uses an internal content filter which blocks some sites, such as those deemed pornographic or otherwise offensive. 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." Additionally, the Falun Gong criticism website facts.org.cn, alleged to be operated by the Chinese government, is also unreachable through UltraSurf.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Ultrasurf

Start with the simplest possible case. Write down what Ultrasurf claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ultrasurf before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ultrasurf ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ultrasurf

In research: Ultrasurf appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Ultrasurf in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Ultrasurf is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anonymity networks, Falun Gong, Internet censorship, so understanding it makes those chapters shorter.
In everyday life: Look for Ultrasurf outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Ultrasurf in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ultrasurf means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Ultrasurf out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ultrasurf in simple terms?

Why does Ultrasurf matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ultrasurf?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ultrasurf.