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Open proxy

Open proxy is a 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 Open proxy rather than just read about it. In short: An open proxy is a type of proxy server that is accessible by any Internet user. Generally, a proxy server only allows users within a network group (i.e., a closed proxy) to store and forward Internet services such as DNS or web pages to reduce and control the bandwidth used by the group.

Open proxy — main illustration
Open proxy — illustration

Key takeaways

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

Reference excerpt

An open proxy is a type of proxy server that is accessible by any Internet user. Generally, a proxy server only allows users within a network group (i.e., a closed proxy) to store and forward Internet services such as DNS or web pages to reduce and control the bandwidth used by the group. With an open proxy, however, any user on the Internet can use this forwarding service.

Advantages An anonymous open proxy is useful to those looking for online anonymity and privacy, as it can help users hide their IP address from web servers since the server requests appear to originate from the proxy server. It makes it harder to reveal their identity and thereby helps preserve their perceived security while browsing the web or using other internet services. Real anonymity and extensive internet security might not be achieved by this measure alone as website operators can use client-side scripts to determine the browser's real IP address and the open proxy may be keeping logs of all connections. Open proxies also do not stop tracking cookies and fingerprinters from identifying users. Most public VPNs work through open proxies.

Disadvantages It is possible for a computer to run as an open proxy server without the computer's owner knowing it. This can result from misconfiguration of proxy software running on the computer, or from infection with malware (viruses, trojans or worms) designed for this purpose. If it is caused by malware, the infected computer is known as a zombie computer.

Testing for access from an open proxy Because open proxies are often implicated in abuse, a number of methods have been developed to detect them and to refuse service to them. IRC networks with strict usage policies automatically test client systems for known types of open proxies. Likewise, a mail server may be configured to automatically test mail senders for open proxies, using software such as proxycheck. Groups of IRC and electronic mail operators run DNSBLs publishing lists of the IP addresses of known open proxies, such as AHBL, CBL, NJABL (till 2013), and SORBS (in operation since 2002). The AHBL discontinued public access in 2015.

See also Anonymizing proxy Open mail relay

References

Illustrations

Open proxy: An open proxy forwarding requests from and to anywhere on the Internet
An open proxy forwarding requests from and to anywhere on the Internet

Worked examples

Example 1 — a first encounter with Open proxy

Start with the simplest possible case. Write down what Open proxy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 Open proxy 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 Open proxy 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 Open proxy

In research
Open proxy appears in 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 Open proxy 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
Open proxy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Internet security, Proxy servers, so understanding it makes those chapters shorter.
In everyday life
Look for Open proxy 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 Open proxy in 20 minutes

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

Frequently asked questions

What is Open proxy in simple terms?

An open proxy is a type of proxy server that is accessible by any Internet user. Generally, a proxy server only allows users within a network group (i.e., a closed proxy) to store and forward Internet services such as DNS or web pages to reduce and control the bandwidth used by the group.

Why does Open proxy matter?

Because it connects several 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 Open proxy?

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 Open proxy.

Tags

  • Internet security
  • Proxy servers

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